WO2025159953A1

WO2025159953A1 - Emissive lcd for virtual reality display

Info

Publication number: WO2025159953A1
Application number: PCT/US2025/011665
Authority: WO
Inventors: Yun Wang; Ruiqing Ma
Original assignee: Meta Platforms Technologies LLC
Current assignee: Meta Platforms Technologies LLC
Priority date: 2024-01-23
Filing date: 2025-01-15
Publication date: 2025-07-31
Anticipated expiration: 2026-07-23

Abstract

An emissive liquid crystal display (LCD) panel includes a first substrate (e.g., a glass substrate) including thin-film transistor (TFT) drive circuits formed thereon, a liquid crystal (LC) cell including LCD pixel electrodes electrically coupled to the TFT drive circuits, and one or more light emitters between the TFT drive circuits and the LC cell and configured to illuminate the LC cell. The one or more light emitters include, for example, white light emitting organic light emitting diodes (OLEDs) or color OLEDs configured to emit red, green, and blue light, and can be controlled globally or in groups.

Description

EMISSIVE LCD FOR VIRTUAL REALITY DISPLAY

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to U.S. Provisional Application No. 63/623,938, filed January' 23, 2024, entitled “EMISSIVE LCD FOR VIRTUAL REALITY DISPLAY’;

FIELD

[0002] This disclosure relates generally to liquid crystal display (LCD) and, in particular, to emissive LCD.

BACKGROUND

[0003] An artificial reality system, such as a head-mounted display (HMD) or heads-up display (HUD) system, generally includes a near-eye display system in the form of a headset or a pair of glasses and configured to present content to a user via an electronic or optic display within, for example, about 10-20 mm in front of the user's eyes. The near-eye display system may display virtual objects or combine images of real objects with virtual objects, as in virtual reality (VR), augmented reality (AR), or mixed reality (MR) applications. A near-eye display generally includes an image source (e.g., a display panel) for displaying computer-generated images and an optical system configured to relay the computer-generated images to create a virtual image that appears to be away from the image source and further than just a few centimeters away from the user's eyes.

SUMMARY

[0004] This disclosure relates generally to liquid cry stal display (LCD). More specifically, and without limitation, techniques disclosed herein relate to low cost, high resolution, and high efficiency emissive LCD panels formed on glass. Vanous inventive embodiments are described herein, including devices, systems, methods, structures, materials, processes, and the like.

[0005] According to a first aspect of the present disclosure there is provided an emissive liquid crystal display (LCD) panel comprising: a first substrate including thin-film transistor (TFT) drive circuits formed thereon: a liquid crystal (LC) cell including LCD pixel electrodes electrically coupled to the TFT drive circuits; and one or more light emitters between the TFT drive circuits and the LC cell and configured to illuminate the LC cell.

[0006] In some embodiments, the first substrate may include a glass substrate.

[0007] In some embodiments, the one or more light emitters may include one or more white light emitting organic light emitting diodes (OLEDs); and the LC cell may include an array of color filters. [0008] In some embodiments, the one or more light emitters may include an array of OLEDs configured to emit light of multiple colors.

[0009] In some embodiments, the one or more light emitters may share a common anode and a common cathode.

[0010] In some embodiments, the TFT drive circuits may include LCD pixel drive circuits and drive circuits for driving the one or more light emitters globally.

[0011] In some embodiments, the one or more light emitters may be divided into a plurality of groups, light emitters in each group of the plurality of groups may be located in a respective region of a plurality of regions of the emissive LCD panel and may be sharing a common anode and a common cathode.

[0012] In some embodiments, the TFT drive circuits may include LCD pixel drive circuits and respective drive circuits for driving each group of light emitters of the plurality’ of groups. [0013] In some embodiments, the respective drive circuits for driving each group of light emitters of the plurality of groups may be configurable to locally dim the group of light emitters in the plurality of groups.

[0014] In some embodiments, the LC cell may include: an LC material layer; and an in- cell polarizer between the LC material layer and the one or more light emitters.

[0015] In some embodiments, the in-cell polarizer may include a polymer polarizer.

[0016] In some embodiments, the in-cell polarizer may be characterized by a thickness less than 2 pm.

[0017] In some embodiments, the emissive LCD panel may further comprise a planarized encapsulation layer between the one or more light emitters and the LC cell.

[0018] In some embodiments, the LCD pixel electrodes may be electrically coupled to the TFT drive circuits through electrical connectors that pass through the one or more light emitters.

[0019] In some embodiments, the emissive LCD panel may be characterized by a resolution greater than 1000 pixels per inch.

[0020] In some embodiments, the emissive LCD panel may be characterized by an active area greater than 1.5 x 1.5 square inches.

[0021] According to certain embodiments, an emissive LCD panel may include a first substrate (e.g., a glass substrate) including thin-film transistor (TFT) drive circuits formed thereon, a liquid crystal (LC) cell including LCD pixel electrodes electrically coupled to the TFT drive circuits, and one or more light emitters (e.g., organic light emitting diodes (OLEDs)) between the TFT drive circuits and the LC cell and configured to illuminate the LC cell.

[0022] According to a second aspect of the present disclosure there is provided a neareye display system comprising: an emissive liquid crystal display (LCD) panel comprising: a first substrate including thin-film transistor (TFT) drive circuits formed thereon; a liquid crystal (LC) cell including LCD pixel electrodes electrically coupled to the TFT drive circuits; and one or more light emitters between the TFT drive circuits and the LC cell and configured to illuminate the LC cell; and display optics configured to project images displayed by the emissive LCD panel to an eye of a user of the near-eye display system.

[0023] In some embodiments, the first substrate may include a glass substrate; the one or more light emitters may include one or more organic light emitting diodes (OLEDs); and the emissive LCD panel may be characterized by an active area greater than 1.5x 1.5 square inches. [0024] In some embodiments, the one or more OLEDs may include white light emitting OLEDs or color light emitting OLEDs.

[0025] In some embodiments, the one or more light emitters may be divided into a plurality of groups, wherein light emitters in each group of the plurality of groups may be in a respective region of a plurality of regions of the emissive LCD panel and may share a common anode and a common cathode; and the TFT drive circuits may include respective drive circuits for driving each group of light emitters of the plurality⁷ of groups and may be configurable to locally dim the group of light emitters in the plurality of groups.

[0026] According to certain embodiments, a near-eye display system may include an emissive LCD panel and display optics. The emissive LCD panel may include a first substrate (e.g., a glass substrate) including thin-film transistor (TFT) drive circuits formed thereon, a liquid cry stal (LC) cell including LCD pixel electrodes electrically coupled to the TFT drive circuits, and one or more light emitters (e.g., organic light emitting diodes (OLEDs)) between the TFT drive circuits and the LC cell and configured to illuminate the LC cell. The display optics may' be configured to project images displayed by the emissive LCD panel to an eye of a user of the near-eye display system.

[0027] It will be appreciated that any features described herein as being suitable for incorporation into one or more aspects or embodiments of the present disclosure are intended to be generalizable across any and all aspects and embodiments of the present disclosure. Other aspects of the present disclosure can be understood by those skilled in the art in light of the description, the claims, and the drawings of the present disclosure. The foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the claims. [0028] This summary' is neither intended to identify key or essential features of the claimed subject matter, nor is it intended to be used in isolation to determine the scope of the claimed subject matter. The subject matter should be understood by reference to appropriate portions of the entire specification of this disclosure, any or all drawings, and each claim.

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Illustrative embodiments are described in detail below with reference to the following figures.

[0030] FIG. 1 is a simplified block diagram of an example of an artificial reality system environment including a near-eye display according to one or more embodiments of the present disclosure.

[0031] FIG. 2 is a perspective view of an example of a near-eye display in the form of a head-mounted display (HMD) device for implementing one or more of the examples disclosed herein.

[0032] FIG. 3 is a perspective view of an example of a near-eye display in the form of a pair of glasses for implementing one or more of the examples disclosed herein.

[0033] FIG. 4 is a cross-sectional view of an example of a near-eye display according to one or more embodiments of the present disclosure.

[0034] FIG. 5 illustrates an example of an optical system with a non-pupil forming configuration for a near-eye display device according to one or more embodiments of the present disclosure.

[0035] FIG. 6 illustrates an example of a liquid crystal display (LCD) panel.

[0036] FIG. 7 illustrates an example of a layer stack of an LCD panel.

[0037] FIG. 8A illustrates an example of a pixel in a transmissive LCD.

[0038] FIG. 8B illustrates an example of an emissive LCD panel according to one or more embodiments of the present disclosure.

[0039] FIG. 9 illustrates an example of an emissive LCD panel according to one or more embodiments of the present disclosure.

[0040] FIG. 10 illustrates another example of an emissive LCD panel according to one or more embodiments of the present disclosure.

[0041] FIG. 11 includes a flowchart illustrating an example of a process of fabricating an emissive LCD panel according to one or more embodiments of the present disclosure.

[0042] FIG. 12 is a simplified block diagram of an example of an electronic system of an example near-eye display (e.g.. HMD device) for implementing some examples disclosed herein, according to one or more embodiments of the present disclosure. [0043] The figures depict embodiments of the present disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated may be employed without departing from the principles, or benefits touted, of this disclosure.

[0044] In the appended figures, similar components and/or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.

DETAILED DESCRIPTION

[0045] This disclosure relates generally to liquid crystal display (LCD). More specifically, and without limitation, techniques disclosed herein relate to low cost, high resolution, and high efficiency emissive LCD panels formed on glass. Various inventive embodiments are described herein, including devices, systems, methods, structures, materials, processes, and the like.

[0046] Augmented reality (AR) and virtual reality (VR) applications may use near-eye displays (e.g., head-mounted displays) to present images to users. A near-eye display system may include an image source (e.g., a display panel) for generating image frames, and display optics for projecting the image frames to the user's eyes. In near-eye display systems, the display panels or image sources may be implemented using, for example, liquid crystal display (LCD), organic light emitting diode (OLED) display, micro-OLED display, active-matrix OLED display (AMOLED), transparent OLED display (TOLED), inorganic light emitting diode (ILED) display, quantum-dot light emitting diode (QLED) display, micro-light emitting diode (micro-LED) display, and the like. It is generally desirable that the image source or the display panel of a near-eye display system has a higher resolution, a large color gamut, a large field of view (FOV), and a high brightness, to improve the immersive experience of using the near-eye display system. In addition, as a wearable device that is mounted on a user's head, it is also desirable that a near-eye display system has a lower weight and a lower thickness. For a battery-powered near-eye display system, it may be desirable that the system has a higher power efficiency to improve the battery life and/or reduce the total weight of the system.

[0047] The FOV of a display system is the angular range over which an image may be projected in the near or far field. The FOV of a display system is generally measured in degrees, and the resolution over the FOV is generally measured in pixels per degree (PPD). The FOV of a display system may be linearly proportional to the size of the image source (e.g., the display panel), and may be inversely proportional to the focal length of the display optics (e.g., a collimation lens or lens assembly). A balance between the size of the image source and the optical power of the display optics may be needed in order to achieve a good modulation transfer function (MTF) and reduced size/weight/cost. For example, for a smaller display panel, the field of view may be increased by bringing the image source closer, but the image source would need to have higher PPD, and the aberrations of the display optics at the periphery may limit the effective field of view and image quality. In addition, to achieve a high PPD, micro displays with ultra-high pixels per inch (PPI) may be needed. There may be many technological challenges and cost issues associated with making high-PPI display panels (e.g., silicon-based pOLED panels or micro-LED panels) with large sizes to cover wider FOVs. For example, when a single dnve circuit die is used, the drive circuit die may need to have large chip dimensions to accommodate the OLED panel, gate and data drivers, and display driver integrated circuits (DDICs) on a single die, and advanced processing technology⁷ with higher cost may need to be used. But production yield of larger chips may be low for a processing technology having a certain defect density⁷. Therefore, micro displays may generally be small due to the limited sizes of the drive circuit dies and/or high cost for large-sized drive circuit dies. As such, the FOVs of current AR/VR/MR systems may be limited, which may adversely affect the user experience.

[0048] Many consumer virtual reality⁷ (VR) near-eye display systems use LCD panels to generate the displayed images. LCD panels for VR applications typically operate in a transmissive mode, yvhere light may be modulated yvhile being transmitted by the LCD panels. For example, a transmissive LCD panel may include a backlight unit (BLU) and a liquid cry stal (LC) panel that may modulate and filter light from the BLU at individual pixels. The LC panel may include a liquid crystal cell sandwiched by a bottom (or back) substrate and a top (or front) substrate. In some implementations, the bottom substrate may include thin-film transistor (TFT) circuits formed on a glass substrate for controlling the liquid cry stal cell, yvhereas the top substrate may include a common electrode and an array of color filters formed thereon. In some implementations, the bottom substrate may include both TFT circuits and an array of color filters formed on a glass substrate (referred to as color filter on array (COA)), yvhereas the top substrate may include a common electrode and a black matrix formed thereon. In some implementations, pixel electrodes and the common electrode may both be formed on the bottom substrate, for example, in fringe field switching (FFS) mode liquid crystal display, whereas the top substrate may include a black matrix and an overcoat layer formed thereon. [0049] LCD panels may offer many advantages over other display technologies, such as lower cost, longer lifetime, higher energy efficiencies, larger sizes, and the like. For example, the pixel drive circuits for LCD panels may be simple (e.g., including one transistor and once capacitor in each 1T1C pixel drive circuit) and thus may be implemented using TFT circuits formed on glass substrates even if the LCD panel has a higher PPI. As such, large LCD panels may be formed on large glass substrates with TFT drive circuits formed thereon, and thus may have much low cost than large display panels implemented using other technologies. However, due to the large inactive area used for the TFT circuits, transmissive LCD panels may have a resolution limitation at about 2000 pixels per inch, even using the most advanced technologies. In addition, high-resolution LC panels (e.g., with a PPI greater than about 600 or higher such as 1400 or higher) may have low panel transmission and thus low power efficiency at least due to the reduced aperture ratio (e.g., the pixel active area over the whole pixel area) of each pixel. For example, some existing display panels may only transmit about 1.5% of the total illumination light.

[0050] Organic LED (OLED) display panels may not have large inactive areas as in transmissive LCD panels and thus may be able to achieve high resolution. However, the drive circuits for OLED display panels may be more complex (e g., using 5-7 transistors for each pixel). OLED display panels formed on glass substrates that include TFT drive circuits formed thereon may only be able to achieve a resolution about 1000 PPI due to the complex pixel drive circuits. Therefore, to achieve a large, high-resolution OLED display panel, a large silicon die with drive circuits formed thereon may be used. But it can be costly to make large-sized OLED display panels on large silicon dies with drive circuits formed thereon due to, for example, the high cost of the large silicon dies as described above.

[0051] According to certain embodiments disclosed herein, emissive LCD panels formed on glass substrates may be used in VR/AR display systems to improve the resolution, field of view, power efficiency, brightness, and other properties of the VR/AR display systems and reduce the cost, weight, and thickness of the VR/AR display systems. In an example of an emissive LCD panel disclosed herein, light emitters (e.g., white or color OLEDs) may be positioned between the LC cell and LCD pixel drive circuits formed on a glass substrate. The light emitters such as OLEDs are used to illuminate the LC cell and thus can be driven globally or in groups, and thus do not need complex drive circuits for individual OLEDs. The drive circuits (including the LCD pixel drive circuits and the global or group drive circuits for the light emitters) may be implemented using TFT circuits on glass substrates under the light emitters and LC cells, and thus would not block the illumination light emitted by the light emitters for illuminating the LC cells. When color light emitters are used, no color filters and black matrix may be needed in the emissive LCD panels. The bottom polarizer for the LC cell can be formed above the light emitters by, for example, coating a thin layer (e.g., less than about 1 pm) of polymer polarizer.

[0052] Since a backlight unit below the LCD pixel drive circuits as used in existing transmissive LCD panels is not used, and the OLEDs for illuminating the LC cell are between the LCD pixel drive circuits (e.g., TFT circuits) and the LC cell, the emissive LCD panels disclosed herein do not have large inactive areas that may block light, and thus may not have high loss due to light blocked by the TFT circuits in the inactive areas as in existing transmissive LCD panels. Therefore, both the resolution and the power efficiency of the emissive LCD panels may be improved compared with transmissive LCD panels. Because no backlight unit is used, the weight and thickness of the emissive LCD panels may be reduced. Furthermore, since the drive circuits (including the LCD pixel drive circuits and the global or group drive circuits for the OLEDs) may be implemented using TFT circuits on glass substrates, the emissive LCD panels can be large (and thus having large FOVs) and have lower costs.

[0053] The emissive LCD panels described herein may be used in conjunction with various technologies, such as an artificial reality system. An artificial reality system, such as a head-mounted display (HMD) or heads-up display (HUD) system, generally includes a display configured to present artificial images that depict objects in a virtual environment. The display may present virtual objects or combine images of real objects with virtual objects, as in virtual reality (VR), augmented reality (AR), or mixed reality (MR) applications. For example, in an AR system, a user may view both displayed images of virtual objects (e.g. , computer-generated images (CGIs)) and the surrounding environment by. for example, seeing through transparent display glasses or lenses (often referred to as optical see-through) or viewing displayed images of the surrounding environment captured by a camera (often referred to as video see-through). [0054] In the following description, for the purposes of explanation, specific details are set forth in order to provide a thorough understanding of examples of the disclosure. However, it will be apparent that various examples may be practiced without these specific details. For example, devices, systems, structures, assemblies, methods, and other components may be shown as components in block diagram form in order not to obscure the examples in unnecessary detail. In other instances, well-known devices, processes, systems, structures, and techniques may be shown without necessary detail in order to avoid obscuring the examples. The figures and description are not intended to be restrictive. The terms and expressions that have been employed in this disclosure are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof. The word “example” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment or design described herein as “example” is not necessarily to be construed as preferred or advantageous over other embodiments or designs.

[0055] FIG. 1 is a simplified block diagram of an example of an artificial reality system environment 100 including a near-eye display 120 in accordance with certain embodiments. Artificial reality system environment 100 shown in FIG. 1 may include near-eye display 120, an optional external imaging device 150, and an optional input/output interface 140, each of which may be coupled to an optional console 110. While FIG. 1 shows an example of artificial reality system environment 100 including one near-eye display 120, one external imaging device 150, and one input/output interface 140, any number of these components may be included in artificial reality system environment 100, or any of the components may be omitted. For example, there may be multiple near-eye displays 120 monitored by one or more external imaging devices 150 in communication with console 110. In some configurations, artificial reality system environment 100 may not include external imaging device 150, optional input/output interface 140, and optional console 110. In alternative configurations, different or additional components may be included in artificial reality system environment 100.

[0056] Near-eye display 120 may be a head-mounted display that presents content to a user. Examples of content presented by near-eye display 120 include one or more of images, videos, audio, or any combination thereof. In some embodiments, audio may be presented via an external device (e.g.. speakers and/or headphones) that receives audio information from near-eye display 120, console 110, or both, and presents audio data based on the audio information. Near-eye display 120 may include one or more rigid bodies, which may be rigidly or non-rigidly coupled to each other. A rigid coupling between rigid bodies may cause the coupled rigid bodies to act as a single rigid entity. A non-rigid coupling between rigid bodies may allow the rigid bodies to move relative to each other. In various embodiments, near-eye display 120 may be implemented in any suitable form-factor, including a pair of glasses. Some embodiments of near-eye display 120 are further described below with respect to FIGS. 2 and 3. Additionally, in various embodiments, the functionality described herein may be used in a headset that combines images of an environment external to near-eye display 120 and artificial reality content (e.g., computer-generated images). Therefore, near-eye display 120 may augment images of a physical, real -world environment external to near-eye display 120 with generated content (e.g, images, video, sound, etc.) to present an augmented reality to a user. [0057] In various embodiments, near-eye display 120 may include one or more of display electronics 122, display optics 124, and an eye-tracking unit 130. In some embodiments, near- eye display 120 may also include one or more locators 126, one or more position sensors 128, and an inertial measurement unit (IMU) 132. Near-eye display 120 may omit any of eyetracking unit 130. locators 126, position sensors 128. and IMU 132, or include additional elements in various embodiments. Additionally, in some embodiments, near-eye display 120 may include elements combining the function of various elements described in conjunction with FIG. 1.

[0058] Display electronics 122 may display or facilitate the display of images to the user according to data received from, for example, console 110. In various embodiments, display electronics 122 may include one or more display panels, such as a liquid crystal display (LCD), an organic light emitting diode (OLED) display, an inorganic light emitting diode (ILED) display, a micro light emitting diode ( LED) display, an active-matrix OLED display (AMOLED), a transparent OLED display (TOLED), or some other display. For example, in one implementation of near-eye display 120, display electronics 122 may include a front TOLED panel, a rear display panel, and an optical component (e.g., an attenuator, polarizer, or diffractive or spectral film) between the front and rear display panels. Display electronics 122 may include pixels to emit light of a predominant color such as red, green, blue, white, or yellow. In some implementations, display electronics 122 may display a three-dimensional (3D) image through stereoscopic effects produced by two-dimensional panels to create a subjective perception of image depth. For example, display electronics 122 may include a left display and a right display positioned in front of a user’s left eye and right eye. respectively. The left and right displays may present copies of an image shifted horizontally relative to each other to create a stereoscopic effect (/.e., a perception of image depth by a user viewing the image).

[0059] In certain embodiments, display optics 124 may display image content optically (e.g., using optical waveguides and couplers) or magnify image light received from display electronics 122, correct optical errors associated with the image light, and present the corrected image light to a user of near-eye display 120. In various embodiments, display optics 124 may include one or more optical elements, such as, for example, a substrate, optical waveguides, an aperture, a Fresnel lens, a convex lens, a concave lens, a filter, input/output couplers, or any other suitable optical elements that may affect image light emitted from display electronics 122. Display optics 124 may include a combination of different optical elements as well as mechanical couplings to maintain relative spacing and orientation of the optical elements in the combination. One or more optical elements in display optics 124 may have an optical coating, such as an antireflective coating, a reflective coating, a filtering coating, or a combination of different optical coatings.

[0060] Magnification of the image light by display optics 124 may allow display electronics 122 to be physically smaller, weigh less, and consume less power than larger displays. Additionally, magnification may increase a field of view of the displayed content. The amount of magnification of image light by display optics 124 may be changed by adj usting, adding, or removing optical elements from display optics 124. In some embodiments, display optics 124 may project displayed images to one or more image planes that may be further away from the user’s eyes than near-eye display 120.

[0061] Display optics 124 may also be designed to correct one or more types of optical errors, such as two-dimensional optical errors, three-dimensional optical errors, or any combination thereof. Two-dimensional errors may include optical aberrations that occur in two dimensions. Example types of two-dimensional errors may include barrel distortion, pincushion distortion, longitudinal chromatic aberration, and transverse chromatic aberration. Three-dimensional errors may include optical errors that occur in three dimensions. Example types of three-dimensional errors may include spherical aberration, comatic aberration, field curvature, and astigmatism.

[0062] Locators 126 may be objects located in specific positions on near-eye display 120 relative to one another and relative to a reference point on near-eye display 120. In some implementations, console 110 may identify locators 126 in images captured by external imaging device 150 to determine the artificial reality headset’s position, orientation, or both. A locator 126 may be a light-emitting diode (LED), a comer cube reflector, a reflective marker, a type of light source that contrasts with an environment in which near-eye display 120 operates, or any combination thereof. In embodiments where locators 126 are active components (e.g, LEDs or other types of light emitting devices), locators 126 may emit light in the visible band (e.g., about 380 nm to 750 nm), in the infrared (IR) band (e.g, about 750 nm to 1 mm), in the ultraviolet band (e.g. , about 12 nm to about 380 nm), in another portion of the electromagnetic spectrum, or in any combination of portions of the electromagnetic spectrum.

[0063] External imaging device 150 may include one or more cameras, one or more video cameras, any other device capable of capturing images including one or more of locators 126, or any combination thereof. Additionally, external imaging device 150 may include one or more filters (e.g, to increase signal to noise ratio). External imaging device 150 may be configured to detect light emitted or reflected from locators 126 in a field of view of external imaging device 150. In embodiments where locators 126 include passive elements (e.g, retroreflectors), external imaging device 150 may include a light source that illuminates some or all of locators 126, which may retro-reflect the light to the light source in external imaging device 150. Slow calibration data may be communicated from external imaging device 150 to console 110, and external imaging device 150 may receive one or more calibration parameters from console 110 to adjust one or more imaging parameters (e.g, focal length, focus, frame rate, sensor temperature, shutter speed, aperture, etc.).

[0064] Position sensors 128 may generate one or more measurement signals in response to motion of near-eye display 120. Examples of position sensors 128 may include accelerometers, gyroscopes, magnetometers, other motion-detecting or error-correcting sensors, or any combination thereof. For example, in some embodiments, position sensors 128 may include multiple accelerometers to measure translational motion (e.g. forward/back. up/down, or left/right) and multiple gyroscopes to measure rotational motion (e.g, pitch, yaw, or roll). In some embodiments, various position sensors may be oriented orthogonally to each other.

[0065] IMU 132 may be an electronic device that generates fast calibration data based on measurement signals received from one or more of position sensors 128. Position sensors 128 may be located external to IMU 132, internal to IMU 132, or any combination thereof. Based on the one or more measurement signals from one or more position sensors 128, IMU 132 may generate fast calibration data indicating an estimated position of near-eye display 120 relative to an initial position of near-eye display 120. For example, IMU 132 may integrate measurement signals received from accelerometers over time to estimate a velocity vector and integrate the velocity vector over time to determine an estimated position of a reference point on near-eye display 120. Alternatively, IMU 132 may provide the sampled measurement signals to console 110. which may determine the fast calibration data. While the reference point may generally be defined as a point in space, in various embodiments, the reference point may also be defined as a point within near-eye display 120 (e.g., a center of IMU 132).

[0066] Eye-tracking unit 130 may include one or more eye-tracking systems. Eye tracking may refer to determining an eye's position, including orientation and location of the eye, relative to near-eye display 120. An eye-tracking system may include an imaging system to image one or more eyes and may optionally include a light emitter, which may generate light that is directed to an eye such that light reflected by the eye may be captured by the imaging system. For example, eye-tracking unit 130 may include a non-coherent or coherent light source (e.g, a laser diode) emitting light in the visible spectrum or infrared spectrum, and a camera capturing the light reflected by the user’s eye. As another example, eye-tracking unit 130 may capture reflected radio waves emitted by a miniature radar unit. Eye-tracking unit 130 may use low-power light emitters that emit light at frequencies and intensities that would not injure the eye or cause physical discomfort. Eye-tracking unit 130 may be arranged to increase contrast in images of an eye captured by eye-tracking unit 130 while reducing the overall power consumed by eye-tracking unit 130 (e.g, reducing power consumed by a light emitter and an imaging system included in eye-tracking unit 130). For example, in some implementations, eye-tracking unit 130 may consume less than 120 milliwatts of power.

[0067] Near-eye display 120 may use the orientation of the eye to, e.g. , determine an inter- pupillary distance (IPD) of the user, determine gaze direction, introduce depth cues (e.g. , blur image outside of the user’s main line of sight), collect heuristics on the user interaction in the VR media (e.g, time spent on any particular subject, object, or frame as a function of exposed stimuli), some other functions that are based in part on the orientation of at least one of the user’s eyes, or any combination thereof. Because the orientation may be determined for both eyes of the user, eye-tracking unit 130 may be able to determine where the user is looking. For example, determining a direction of a user’s gaze may include determining a point of convergence based on the determined orientations of the user’s left and right eyes. A point of convergence may be the point where the two foveal axes of the user’s eyes intersect. The direction of the user’s gaze may be the direction of a line passing through the point of convergence and the mid-point between the pupils of the user’s eyes.

[0068] Input/output interface 140 may be a device that allows a user to send action requests to console 110. An action request may be a request to perform a particular action. For example, an action request may be to start or to end an application or to perform a particular action within the application. Input/output interface 140 may include one or more input devices. Example input devices may include a keyboard, a mouse, a game controller, a glove, a button, a touch screen, or any other suitable device for receiving action requests and communicating the received action requests to console 110. An action request received by the input/output interface 140 may be communicated to console 110, which may perform an action corresponding to the requested action. In some embodiments, input/output interface 140 may provide haptic feedback to the user in accordance with instructions received from console 110. For example, in ut/output interface 140 may provide haptic feedback when an action request is received, or when console 110 has performed a requested action and communicates instructions to input/output interface 140. In some embodiments, external imaging device 150 may be used to track input/output interface 140, such as tracking the location or position of a controller (which may include, for example, an IR light source) or a hand of the user to determine the motion of the user. In some embodiments, near-eye display 120 may include one or more imaging devices to track input/output interface 140. such as tracking the location or position of a controller or a hand of the user to determine the motion of the user.

[0069] Console 110 may provide content to near-eye display 120 for presentation to the user in accordance with information received from one or more of external imaging device 150, near-eye display 120, and input/output interface 140. In the example shown in FIG. 1, console 110 may include an application store 112, a headset tracking subsystem 114, an artificial reality engine 116, and an eye-tracking subsystem 118. Some embodiments of console 110 may include different or additional devices or subsystems than those described in conjunction with FIG. 1. Functions further described below may be distributed among components of console 110 in a different manner than is described here.

[0070] In some embodiments, console 110 may include a processor and a non-transitory computer-readable storage medium storing instructions executable by the processor. The processor may include multiple processing units executing instructions in parallel. The non- transitory computer-readable storage medium may be any memory, such as a hard disk drive, a removable memory, or a solid-state drive (e.g, flash memory or dynamic random access memory' (DRAM)). In various embodiments, the devices or subsystems of console 110 described in conjunction with FIG. 1 may be encoded as instructions in the non-transitory computer-readable storage medium that, when executed by the processor, cause the processor to perform the functions further described below.

[0071] Application store 112 may store one or more applications for execution by console 110. An application may include a group of instructions that, when executed by a processor, generates content for presentation to the user. Content generated by an application may be in response to inputs received from the user via movement of the user’s eyes or inputs received from the input/output interface 140. Examples of the applications may include gaming applications, conferencing applications, video playback application, or other suitable applications.

[0072] Headset tracking subsystem 114 may track movements of near-eye display 120 using slow calibration information from external imaging device 150. For example, headset tracking subsystem 114 may determine positions of a reference point of near-eye display 120 using observed locators from the slow calibration information and a model of near-eye display 120. Headset tracking subsystem 1 14 may also determine positions of a reference point of near- eye display 120 using position information from the fast calibration information. Additionally, in some embodiments, headset tracking subsystem 114 may use portions of the fast calibration information, the slow calibration information, or any combination thereof, to predict a future location of near-eye display 120. Headset tracking subsystem 114 may provide the estimated or predicted future position of near-eye display 120 to artificial reality engine 116.

[0073] Artificial reality' engine 116 may execute applications within artificial reality system environment 100 and receive position information of near-eye display 120, acceleration information of near-eye display 120, velocity information of near-eye display 120, predicted future positions of near-eye display 120, or any combination thereof from headset tracking subsystem 114. Artificial reality engine 116 may also receive estimated eye position and orientation information from eye-tracking subsystem 118. Based on the received information, artificial reality engine 116 may determine content to provide to near-eye display 120 for presentation to the user. For example, if the received information indicates that the user has looked to the left, artificial reality engine 116 may generate content for near-eye display 120 that mirrors the user’s eye movement in a virtual environment. Additionally, artificial reality' engine 116 may perform an action within an application executing on console 110 in response to an action request received from input/output interface 140, and provide feedback to the user indicating that the action has been performed. The feedback may be visual or audible feedback via near-eye display 120 or haptic feedback via input/output interface 140.

[0074] Eye-tracking subsystem 118 may receive eye-tracking data from eye-tracking unit 130 and determine the position of the user’s eye based on the eye tracking data. The position of the eye may include an eye’s orientation, location, or both relative to near-eye display 120 or any element thereof. Because the eye’s axes of rotation change as a function of the eye’s location in its socket, determining the eye’s location in its socket may allow eye-tracking subsystem 118 to more accurately determine the eye’s orientation.

[0075] FIG. 2 is a perspective view of an example of a near-eye display in the form of an HMD device 200 for implementing some of the examples disclosed herein. HMD device 200 may be a part of, e.g. , a VR system, an AR system, an MR system, or any combination thereof. HMD device 200 may include a body 220 and a head strap 230. FIG. 2 shows a bottom side 223, a front side 225, and a left side 227 of body 220 in the perspective view. Head strap 230 may have an adjustable or extendible length. There may be a sufficient space between body 220 and head strap 230 of HMD device 200 for allowing a user to mount HMD device 200 onto the user's head. In various embodiments, HMD device 200 may include additional, fewer, or different components. For example, in some embodiments, HMD device 200 may include eyeglass temples and temple tips as shown in, for example, FIG. 3 below, rather than head strap 230.

[0076] HMD device 200 may present to a user media including virtual and/or augmented views of a physical, real-world environment with computer-generated elements. Examples of the media presented by HMD device 200 may include images (e.g., two-dimensional (2D) or three-dimensional (3D) images), videos (e.g, 2D or 3D videos), audio, or any combination thereof. The images and videos may be presented to each eye of the user by one or more display assemblies (not shown in FIG. 2) enclosed in body 220 of HMD device 200. In various embodiments, the one or more display assemblies may include a single electronic display panel or multiple electronic display panels (e.g. , one display panel for each eye of the user). Examples of the electronic display panel(s) may include, for example, an LCD, an OLED display, an ILED display, a LILED display, an AMOLED, a TOLED, some other display, or any combination thereof. HMD device 200 may include two eye box regions.

[0077] In some implementations, HMD device 200 may include various sensors (not shown), such as depth sensors, motion sensors, position sensors, and eye tracking sensors. Some of these sensors may use a structured light pattern for sensing. In some implementations, HMD device 200 may include an input/output interface for communicating with a console. In some implementations, HMD device 200 may include a virtual reality engine (not shown) that can execute applications within HMD device 200 and receive depth information, position information, acceleration information, velocity' information, predicted future positions, or any combination thereof of HMD device 200 from the various sensors. In some implementations, the information received by the virtual reality engine may be used for producing a signal (e.g., display instructions) to the one or more display assemblies. In some implementations, HMD device 200 may include locators (not shown, such as locators 126) located in fixed positions on body 220 relative to one another and relative to a reference point. Each of the locators may emit light that is detectable by an external imaging device.

[0078] FIG. 3 is a perspective view of an example of a near-eye display 300 in the form of a pair of glasses for implementing some of the examples disclosed herein. Near-eye display 300 may be aspecific implementation ofnear-eye display 120 ofFIG. 1, andmay be configured to operate as a virtual reality display, an augmented reality display, and/or a mixed reality display. Near-eye display 300 may include a frame 305 and a display 310. Display 310 may be configured to present content to a user. In some embodiments, display 310 may include display electronics and/or display optics. For example, as described above with respect to near-eye display 120 of FIG. 1, display 310 may include an LCD panel, an LED display panel, or an optical display panel (e.g., a waveguide display assembly).

[0079] Near-eye display 300 may further include various sensors 350a, 350b, 350c, 350d, and 350e on or within frame 305. In some embodiments, sensors 350a-350e may include one or more depth sensors, motion sensors, position sensors, inertial sensors, or ambient light sensors. In some embodiments, sensors 350a-350e may include one or more image sensors configured to generate image data representing different fields of views in different directions. In some embodiments, sensors 350a-350e may be used as input devices to control or influence the displayed content of near-eye display 300, and/or to provide an interactive VR/AR/MR experience to a user of near-eye display 300. In some embodiments, sensors 350a-350e may also be used for stereoscopic imaging.

[0080] In some embodiments, near-eye display 300 may further include one or more illuminators 330 to project light into the physical environment. The projected light may be associated with different frequency bands (e.g.. visible light, infra-red light, ultra-violet light, etc.), and may serve various purposes. For example, illuminator(s) 330 may project light in a dark environment (or in an environment with low intensity of infra-red light, ultra-violet light, etc.) to assist sensors 350a-350e in capturing images of different objects within the dark environment. In some embodiments, illuminator(s) 330 may be used to project certain light patterns onto the objects within the environment. In some embodiments, illuminator(s) 330 may be used as locators, such as locators 126 described above with respect to FIG. 1.

[0081] In some embodiments, near-eye display 300 may also include a high-resolution camera 340. High-resolution camera 340 may capture images of the physical environment in the field of view . The captured images may be processed, for example, by a virtual reality engine (e. g. , artificial reality engine 116 of FIG. 1 ) to add virtual obj ects to the captured images or modify physical objects in the captured images, and the processed images may be displayed to the user by display 310 for AR or MR applications.

[0082] FIG. 4 is a cross-sectional view of an example of a near-eye display 400 according to certain embodiments. Near-eye display 400 may include at least one display assembly 410. Display assembly 410 may be configured to direct image light (e.g., display light) to an eyebox located at an exit pupil 420 and to user's eye 490. It is noted that, even though FIG. 4 and other figures in the present disclosure show an eye of a user of the near-eye display for illustration purposes, the eye of the user is not a part of the corresponding near-eye display. [0083] As HMD device 200 and near-eye display 300, near-eye display 400 may include a frame 405 and display assembly 410 that may include a display 412 and/or display optics 414 coupled to or embedded in frame 405. As described above, display 412 may display images to the user electrically (e.g., using LCDs, LEDs, OLEDs) or optically (e.g., using a waveguide display and optical couplers) according to data received from a processing unit, such as console 110. In some embodiments, display 412 may include a display panel that includes pixels made of LCDs. LEDs. OLEDs, and the like. Display 412 may include sub-pixels to emit light of a predominant color, such as red, green, blue, white, or yellow. In some embodiments, display assembly 410 may include a stack of one or more waveguide displays including, but not restricted to, a stacked waveguide display, a varifocal waveguide display, and the like. The stacked waveguide display may be a polychromatic display (e.g., a red-green-blue (RGB) display) created by stacking waveguide displays whose respective monochromatic sources are of different colors.

[0084] Display optics 414 may be similar to display optics 124 and may display image content optically (e.g.. using optical waveguides and optical couplers), correct optical errors associated with the image light, combine images of virtual objects and real objects, and present the corrected image light to exit pupil 420 of near-eye display 400, where the user's eye 490 may be located. In some embodiments, display optics 414 may also relay the images to create virtual images that appear to be away from display 412 and further than just a few centimeters away from the eyes of the user. For example, display optics 414 may collimate the image source to create a virtual image that may appear to be far away (e.g., greater than about 0.3 m, such as about 0.5 m, Im, or 3 m away) and convert spatial information of the displayed virtual objects into angular information. In some embodiments, display optics 414 may also magnify the source image to make the image appear larger than the actual size of the source image. More details of display 412 and display optics 414 are described below.

[0085] In various implementations, the optical system of a near-eye display, such as an HMD, may be pupil-forming or non-pupil-forming. Non-pupil-forming HMDs may not use intermediary optics to relay the displayed image, and thus the user's pupils may serve as the pupils of the HMD. Such non-pupil-forming displays may be variations of a magnifier (sometimes referred to as ‘‘simple eyepiece”), which may magnify a displayed image to form a virtual image at a greater distance from the eye. The non-pupil-forming display may use fewer optical elements. Pupil-forming HMDs may use optics similar to, for example, optics of a compound microscope or telescope, and may include some forms of projection optics that magnify an image and relay it to the exit pupil. [0086] FIG. 5 illustrates an example of an optical system 500 with a non-pupil forming configuration for a near-eye display device according to certain embodiments. Optical system 500 may be an example of near-eye display 400, and may include display optics 510 and an image source 520 (e.g., a display panel). Display optics 510 may function as a magnifier. FIG. 5 shows that image source 520 is in front of display optics 510. In some other embodiments, image source 520 may be located outside of the field of view of the user's eye 590. For example, one or more deflectors or directional couplers may be used to deflect light from an image source to make the image source appear to be at the location of image source 520 shown in FIG. 5. Image source 520 may be an example of display 412 described above. For example, image source 520 may include a two-dimensional array of light emitters, such as semiconductor micro-LEDs ormicro-OLEDs. The dimensions and pitches of the light emitters in image source 520 may be small. For example, each light emitter may have a diameter less than 2 pm (e.g., about 1.2 pm) and the pitch may be less than 2 pm (e.g., about 1.5 pm). As such, the number of light emitters in image source 520 can be equal to or greater than the number of pixels in a display image, such as 960x720, 1280x720, 1440x1080, 1920 1080, 2160x1080, 2560 1080, or even more pixels. Thus, a display image may be generated simultaneously by image source 520.

[0087] Light from an area (e.g., a pixel or a light emitter) of image source 520 may be directed to a user's eye 590 by display optics 510. Light directed by display optics 510 may form virtual images on an image plane 530. The location of image plane 530 may be determined based on the location of image source 520 and the focal length of display optics 510. A user's eye 590 may form a real image on the retina of user's eye 590 using light directed by display optics 510. In this way, objects at different spatial locations on image source 520 may appear to be objects on an image plane far away from user's eye 590 at different viewing angles. Image source 520 may have a size larger or smaller than the size (e.g., aperture) of display optics 510. Some light emitted from image source 520 with large emission angles (as shown by light rays 522 and 524) may not be collected and directed to user's eye 590 by display optics 510, and may become stray light.

[0088] The display panels or image sources described above (e.g., display 412 or image source 520) may be implemented using, for example, a liquid cry stal display (LCD), an organic light emitting diode (OLED) display, a micro-OLED display, an inorganic light emitting diode (ILED) display, a micro-light emitting diode (micro-LED) display, an active-matrix OLED display (AMOLED), a transparent OLED display (TOLED), or some other displays. In anear- eye display system, it is generally desirable that the image source or the display panel has a higher resolution and a large size, such that the near-eye display system may have a large field of view (FOV) and better image quality to, for example, improve the immersive experience of using the near-eye display system. The FOV of a display system is the angular range over which an image may be projected in the near or far field. The FOV of a display system is generally measured in degrees, and the resolution over the FOV is generally measured in pixels per degree (PPD). The FOV of a display system may be linearly proportional to the size of the image source (e g., the display panel), and may be inversely proportional to the focal length of the display optics (e.g., a collimation lens or lens assembly). A balance between the size of the image source and the optical power of the display optics may be needed in order to achieve a good modulation transfer function (MTF) and reduced size/weight/cost. The field of view may be increased by bringing the image source closer, but the image source would need to have higher PPD, and the aberrations of the display optics at the periphery may limit the effective field of view. To achieve a high PPD, micro displays with ultra-high pixels per inch (PPI) maybe needed. There may be many technological challenges and cost issues associated with making high-PPI display panels, such as high resolution LCD panels.

[0089] Many consumer virtual reality (VR) near-eye display systems use LCD panels to generate the displayed images. LCD panels for VR applications typically operate in a transmissive mode, where light may be modulated while being transmitted by the LCD panels. For example, a transmissive LCD panel may include a backlight unit (BLU) and a liquid crystal (LC) panel that may modulate and filter light from the BLU at individual pixels. The LC panel may include a liquid crystal cell sandwiched by a bottom (or back) substrate and a top (or front) substrate. In some implementations, the bottom substrate may include thin-film transistor (TFT) circuits formed on a glass substrate for controlling the liquid crystal cell, whereas the top substrate may include a common electrode and an array of color filters formed thereon. In some implementations, the bottom substrate may include both TFT circuits and an array of color filters formed on a glass substrate (referred to as color filter on array (COA)), whereas the top substrate may include a common electrode and a black matrix formed thereon. In some implementations, pixel electrodes and the common electrode may both be formed on the bottom substrate, for example, in fringe field switching (FFS) mode liquid crystal display, whereas the top substrate may include a black matrix and an overcoat layer formed thereon.

[0090] FIG. 6 illustrates an example of an LCD panel 600. As illustrated, LCD panel 600 may include a backlight unit (BLU) 610 configured to emit illumination light, a first polarizer 620 configured to control the type of light that can pass through (e.g., based on the polarization state of the light), an LCD cell that may modulate (e.g.. the phase or polarization state of) the incident light, and a second polarizer 660 for control the type of light that can pass through (e.g., based on the polarization state of the light). In some embodiments, BLU 610 may include a light source (e.g., a cold-cathode fluorescent lamp) configured to emit white light. In some embodiments, BLU 610 may include blue light-emitting LEDs, a light guide plate, and a quantum dot film that includes quantum dots for converting some blue light to red light and green light.

[0091] In the illustrated example, the LCD cell may include a first substrate 630 (e.g., a glass substrate or another transparent dielectric substrate) including a thin-film transistor (TFT) array 632 formed thereon. TFT array 632 may include an array of transistors for controlling the intensity of each pixel (e.g., by controlling the orientations of the liquid crystal molecules in a liquid crystal layer, thereby controlling the rotation angle of the polarization direction of the incident light). The LCD cell may also include a second substrate 640 with a common electrode 644 and a color filter (CF) /black-matrix (BM) array 642 formed thereon. One or more liquid cry stal layers 650 may be sandwiched by first substrate 630 and second substrate 640.

[0092] In some other implementations, first substrate 630 may include both TFT array 632 and color filters formed on TFT array 632 to form a color filter on array (COA) structure, whereas the top substrate may include a common electrode and a black matrix formed on another glass substrate. The COA structure may enable a simplified process, improved aperture ratio, and reduced production cost. In some implementations, the LCD cell may be a fringe field switching (FFS) mode LCD cell, where the pixel electrodes and the common electrode may both be formed on the bottom substrate, and the top substate may include a black matrix and an overcoat layer formed thereon.

[0093] Light emitted by BLU 610 (e.g., white light or blue light) may be polarized by first polarizer 620 (e.g., a linear polarizer with a polarizing axis in a first direction). The polarized light may pass through an array of apertures between the TFTs in TFT array 632. The polarized light may be modulated by the one or more liquid crystal layers 650 to change the polarization state (e.g., the polarization direction) according to the voltage signal applied to each region of the one or more liquid crystal layers 650. CF/BM array 642 may include red, green, and blue color filters for color subpixels, where each color filter may allow light of one color to pass through. Light passing through each color filter may become a subpixel of a color image pixel that may include three subpixels, and may be filtered by second polarizer 660 such that the change in the polarization state may be converted into a change in the light intensity or brightness. For example, second polarizer 660 may include a linear polarizer with a polarizing axis in a second direction that may be the same as or different from the first direction.

[0094] FIG. 7 illustrates an example of a layer stack of an LCD panel 700. LCD panel 700 may be an example of LCD panel 600. In the illustrated example, LCD panel 700 may include a BLU 710, a first polarizer 720, a first substrate 730 including a TFT array and/or black-mask 732 and an array of apertures 734 formed thereon, a common electrode layer 735, a second substrate 740 with a CF/BM array including a black-matrix layer 742 and optionally an array of color filters 744 in black-matrix layer 742, and a second polarizer 750. BLU 710 may be similar to BLU 610 described above. TFT array and/or black-mask 732 may include TFT circuits (e.g., TFTs. gate electrodes, source electrodes, etc.) for controlling liquid crystal molecules filled between first substrate 730 and second substrate 740. Common electrode layer 735 may include a transparent conductive oxide (TCO), such as indium tin oxide (ITO). Color filters 744 may include red, green, and blue color filters for color subpixels. Centers of color filters 744 may align with corresponding centers of apertures 734 on first substrate 730, such that light from BLU 710 and first polarizer 720 may pass through apertures 734 and color filters 744. Second polarizer 750 may include a linear polarizer with a polarizing axis in a direction that is different from or same as the direction of the polarizing axis of first polarizer 720. For example, the direction of the polarizing axis of first polarizer 720 may be orthogonal to the direction of the polarizing axis of second polarizer 750. First polarizer 720 and second polarizer 750 may be used in combination to convert the change in the polarization state (e.g., polarization direction) by the liquid crystal layer to change in the light intensity so as to display images to user's eyes.

[0095] As described above with respect to FIG. 6, in some implementations, instead of forming color filters 744 on a separate substrate, color filters 744 may be formed on first substrate 730 (e.g., between TFT array and/or black-mask 732) to form a COA structure. In some implementations, the LCD cell may be an FFS mode LCD cell, where both the pixel electrodes and the common electrode may be formed on first substrate 730 that includes the TFT array and/or black-mask 732. In other implementations, the TFT array, the color filters, the black matrix, and the electrodes may be arranged in other manners on the two substates that sandwich the liquid crystal material.

[0096] Even though not shown in FIG. 7, spacers (e.g., plastic spacers) may be used between TFT array and/or black-mask 732 and common electrode layer 735 to separate TFT array and/or black-mask 732 and common electrode layer 735 so that liquid crystal materials may be filled between TFT array and/or black-mask 732 (or a protective or planarization layer 736) and common electrode layer 735 to modulate incident light. For example, TFT array and/or black-mask 732 may include column spacers formed thereon (e.g., on top of source electrodes), and the CF/BM array (or black-matrix layer 742 or common electrode layer 735) may include photo spacers formed thereon. When first substrate 730 and second substrate 740 are assembled to form an LCD cell, photo spacers may sit on corresponding column spacers to achieve the desired separation between TFT array and/or black-mask 732 and the CF/BM array (or black-matrix layer 742 or common electrode layer 735).

[0097] As described above, LCD panels may offer many advantages over other display technologies, such as lower cost, longer lifetime, higher energy efficiencies, larger sizes, and the like. For example, the pixel drive circuits for LCD panels may be simple (e g., including one transistor and once capacitor in each 1T1C pixel drive circuit) and thus may be implemented using TFT circuits formed on glass substrates even if the LCD panel has a higher PPL As such, large LCD panels may be formed on large glass substrates with TFT drive circuits formed thereon, and thus may have much low cost than large display panels implemented using other technologies. However, due to the large inactive area used for the TFT circuits, transmissive LCD panels may have a resolution limitation at about 2000 pixels per inch, even using the most advanced technologies. In addition, high-resolution LC panels (e g., with a PPI greater than about 600 or higher such as 1400 or higher) may have low panel transmission and thus low power efficiency at least due to the reduced aperture ratio (e.g., the pixel active area over the whole pixel area) of each pixel. For example, some existing display panels may only transmit about 1.5% of the total illumination light.

[0098] FIG. 8A illustrates an example of a pixel in a transmissive LCD 800. As described above with respect to, for example, FIGS. 6 and 7, transmissive LCD 800 may include a first substrate 810 (e.g., a glass substrate), a second substrate 850 (e.g.. another glass substrate), and a liquid crystal material layer 840 between first substrate 810 and second substrate 850. Electrodes may be formed on first substrate 810 and second substrate 850. Pixel circuits (e.g., TFT circuits), bus lines, black mask/matrix, and the like may be formed on first substrate 810, and may occupy an opaque area 820 in each pixel area where light may not be able to pass through. Illumination light (from a backlight unit) may only pass through an active pixel area 830 that may be much smaller than the total pixel area. Therefore, in each pixel area, only a portion of the incident backlight may pass through. Because a large portion of the incident backlight may be blocked by opaque area 820, the energy efficiency of transmissive LCD 800 may be low. To have a sufficiently large active pixel area for each pixel to achieve the desired brightness, contrast, and other image qualify, the pixel area may need to be large. Therefore, it may be difficult to achieve high pixel density or resolution in transmissive LCD 800.

[0099] OLED display panels may not have large inactive areas as in transmissive LCD panels and thus may be able to achieve high resolution. However, the drive circuits for OLED display panels may be more complex (e.g., using 5-7 transistors for each pixel). OLED display panels formed on glass substrates that include TFT drive circuits formed thereon may only be able to achieve a resolution about 1000 PPI due to the complex pixel drive circuits. Therefore, to achieve a large, high-resolution OLED display panel, a large silicon die with drive circuits formed thereon may be used. But it can be costly to make large-sized OLED display panels on large silicon dies with drive circuits formed thereon due to, for example, the high cost of the large silicon dies.

[0100] According to certain embodiments disclosed herein, emissive LCD panels formed on glass substrates may be used in VR/AR display systems to improve the resolution, field of view, power efficiency, brightness, and other properties of the VR/AR display systems and reduce the cost, weight, and thickness of the VR/AR display systems. In an example of an emissive LCD panel disclosed herein, light emitters (e.g., white or color OLEDs) may be positioned between the LC cell and LCD pixel drive circuits formed on a glass substrate. The light emitters such as OLEDs are used to illuminate the LC cell and thus can be driven globally or in groups, and thus do not need complex drive circuits for individual OLEDs. The drive circuits (including the LCD pixel drive circuits and the global or group drive circuits for the light emitters) may be implemented using TFT circuits on glass substrates under the light emitters and LC cells, and thus would not block the illumination light emitted by the light emitters for illuminating the LC cells. When color light emitters are used, no color filters and black matrix may be needed in the emissive LCD panels. The bottom polarizer for the LC cell can be formed above the light emitters by, for example, coating a thin layer (e.g., less than about 1 pm) of polymer polarizer.

[0101] FIG. 8B illustrates an example of an emissive LCD panel 802 according to certain embodiments. Emissive LCD panel 802 may include a first substrate 812, LCD pixel drive circuits 822 formed on first substrate 812, one or more light emitters 832 (e.g., OLEDs) above LCD pixel drive circuits 822, an LC cell 842, and a second substrate 852. A top polarizer (also referred to as an analyzer) may be included in or positioned on second substrate 852. In emissive LCD panel 802, light emiters 832 (e.g., OLEDs) may be turned on globally or locally to illuminate LC cell 842 globally or locally. The emited light may be polarized by a polarizer. The polarized light may be filtered (if light emited by light emiters 832 is white light) before or after entering LC cell 842. LC cell 842 may be controlled by LCD pixel drive circuits 822 to modulate the light transmitted through LC cell 842 as described above with respect to, for example, FIGS. 6-8 A. The light transmitted through and modulated by LC cell 842 may be filtered by another polarizer to display images with the desired pixel color and intensity.

[0102] First substrate 812 may include, for example, a dielectric that has low leakage, such as a glass substrate. LCD pixel drive circuits 822 may include, for example. TFT circuits formed on the glass substrate. For example, as described above, each LCD pixel drive circuit may be a 1T1C drive circuit that includes one transistor and one capacitor. Circuits on first substrate 812 may also include drive circuits (e.g., TFT circuits) for globally or locally driving one or more light emitters 832. But light emitters 832 may not need to be individually addressable or controllable. Therefore, the drive circuits for driving light emitters 832 may not be complex and may only use a small area on first substrate 812.

[0103] The one or more light emitters 832 may include white light emitters or color light emitters. In one example, each light emitter 832 may include an OLED that may include, for example, a hole injection layer, a hole transport layer, an emissive layer, an electron transport layer, an electron injection layer, and electrode layers. In some implementations, light emitters 832 may include, for example, thermally evaporated OLEDs or solution-processed OLEDs. For example, the multi-layer structure of the OLEDs may be formed by processes such as spin coating, ultrasonic spray coating, blade coating, inkjet printing, and the like.

[0104] In some implementations, the one or more light emitters 832 may share a common anode and a common cathode, and may be turned on or off together. In some implementations, light emitters configured to emit light of a same color (e.g., red, green, or blue) may be grouped together to share a common anode and a common cathode and thus may be turned on or off together. In some implementations, the one or more light emitters may be divided into a plurality of groups in a plurality of regions of the display panel, and light emitters in each respective group (and region) may share a common anode and a common cathode and thus may be controlled together by a same circuit. In some implementations, the one or more light emitters may be divided based on their regions and color of emitted light, where light emitters in each respective region and configured to emit light of the same color may be grouped to share a common anode and a common cathode and thus may be controlled together using a same control circuit.

[0105] LC cell 842 may be formed on light emitters 832, such as on a passivation layer, a planarization layer, or an encapsulation layer (not shown in FIG. 8B) formed on light emitters 832. As described above, LC cell 842 may include a liquid crystal material layer between two substrates (or material layers) including second substrate 852. Electrodes for applying electrical fields across the liquid crystal material layer may be formed on the two substrates. The electrodes may include a common electrode and pixel electrodes. For example, the common electrode may be formed on second substrate 852, and pixel electrodes may be formed on the opposing side of the liquid cry stal material layer. Even though not shown in FIG. 8B, LC cell 842 may also include alignments layers, color filters, a polarizer (e.g., a bottom polarizer), and the like, as describe above with respect to FIGS. 6-8 A.

[0106] Since a backlight unit below the LCD pixel drive circuits as used in existing transmissive LCD panels is not used, and the OLEDs for illuminating the LC cell are between the LCD pixel drive circuits (e.g., TFT circuits) and the LC cell, the emissive LCD panels disclosed herein do not have large inactive areas that may block light, and thus may not have high loss due to light blocked by the TFT circuits in the inactive areas as in existing transmissive LCD panels. Therefore, both the resolution and the power efficiency of the emissive LCD panels may be improved compared with transmissive LCD panels. Because no backlight unit is used, the weight and thickness of the emissive LCD panels may be reduced. Furthermore, since the drive circuits (including the LCD pixel drive circuits and the global or group drive circuits for the OLEDs) may be implemented using TFT circuits on glass substrates, the emissive LCD panels can be large (and thus having large FOVs) and have lower costs.

[0107] FIG. 9 illustrates an example of an emissive LCD panel 900 according to certain embodiments. Emissive LCD panel 900 may be an example of emissive LCD panel 802 described above. In the illustrated example, emissive LCD panel 900 may include one or more white light emitting OLEDs 932 and color filters 960, 962, and 964 for providing color illumination light to an LC cell. The one or more white light emitting OLEDs 932 may be driven and controlled in groups or globally, rather than being controlled individually. For example, in some implementations, OLEDs 932 in each respective region of a plurality of regions of emissive LCD panel 900 may be grouped together and share the same electrodes and control circuit, such that local dimming may be implemented in each respective region of the plurality of regions of emissive LCD panel 900 to reduce power consumption. In some implementations, OLEDs 932 used to illuminate color filters for a same color may be grouped together and share the same electrodes and control circuit.

[0108] In the example illustrated in FIG. 9, emissive LCD panel 900 may include a first substrate 910 (e.g.. including a dielectric material such as glass) and LCD pixel drive circuits 920 (e.g., TFT circuits) formed on first substrate 910. A dielectric layer 922 may be deposited on LCD pixel drive circuits 920 to encapsulate and electrically isolate LCD pixel drive circuits 920. Dielectric layer 922 may include, for example, SiCh, SiN, AI2O3. and the like, and may be thinned and planarized, for example, using chemical mechanical planarization (CMP), to form a thin layer with a flat top surface. In some implementations, OLED drive circuits may also be implemented using TFT circuits fabricated on first substrate 910. In some other implementations, the OLEDs may be controlled using drive circuits outside of the active area, and a common cathode and a common anode in the active area.

[0109] The one or more white light emitting OLEDs 932 and their electrodes may then be formed on dielectric layer 922. For example, a first OLED electrode layer 930 (e.g., an anode layer) may be formed on dielectric layer 922, OLEDs 932 with multi-layer structures as described above may be formed on first OLED electrode layer 930 (e.g.. using thermally evaporated techniques or solution-processed techniques), and a second OLED electrode layer 934 (e.g., a cathode layer) may be deposited on OLEDs 932. First OLED electrode layer 930 may include a conductive and reflective material, such as a metal or a metal alloy (e.g., Cu, Al, Ag, etc ), and may be used to reflect light emitted by OLED back towards the LC cell. In some embodiments, first OLED electrode layer 930 may be patterned to form a plurality of groups of OLEDs 932 in a plurality of regions (e.g., a two-dimensional array of regions). Second OLED electrode layer 934 may include a transparent conductive material, such as a transparent conductive oxide (TCO, e.g., indium tin oxide (ITO)). First OLED electrode layer 930 and second OLED electrode layer 934 may be connected to the OLED drive circuits formed on first substrate 910, or may be connected to a control circuit (e.g., a switchable power source) outside of the active area to turn on the OLEDs. As described above, each OLED 932 may include, for example, a hole injection layer, a hole transport layer, an emissive layer, an electron transport layer, and an electron injection layer, where the multi-layer structure may be formed by processes such as spin coating, ultrasonic spray coating, blade coating, inkjet printing, and the like.

[0110] A dielectric layer 938 (e.g., including SiO2, SiN, AI2O3, etc.) may be deposited on second OLED electrode layer 934 to encapsulate and electrically isolate the OLEDs and their electrodes. Dielectric layer 938 may be used as a substrate for the LC cell. Dielectric layer 938 may be thinned and planarized (e g., using CMP techniques) to form a thin-film encapsulation (TFE) layer having a flat top surface. A first LCD pixel electrode layer 940 may then be deposited on dielectric layer 938, and may be patterned to form individual electrodes for individual LCD subpixels, where the individual electrodes may be connected to LCD pixel drive circuits 920 through, for example, vias 936 or other electrical connectors that pass through dielectric layer 938 and the OLED layers. As second OLED electrode layer 934, first LCD pixel electrode layer 940 may also include a TCO such as ITO to allow light emitted by OLEDs 932 to pass through. A polarizer layer 950 may be coated on first LCD pixel electrode layer 940 to form a polarizer (e.g., a bottom polarizer) for the LC cell. As described above, the polarizer may include a thin layer (e.g., less than about 1 pm) of a polymer polarizer. In some embodiments, polarizer layer 950 may be formed on dielectric layer 938, before depositing first LCD pixel electrode layer 940.

[OHl] Color filters 960, 962, and 964 may be formed on polarizer layer 950, and may include red, green, and blue filters for color subpixels of each pixel. In some implementations, color filters 960, 962, and 964 may be positioned in a black matrix. In some implementations, color filters 960, 962, and 964 may be positioned on top of the LC cell. Even though not show n in FIG. 9, in some implementations, a passivation layer and/or an alignment layer may be formed on color filters 960, 962, and 964 to isolate the LC materials and/or align the LC molecules in the LC materials. A liquid crystal material layer 970 may be between the color filters (and the passivation layer and/or alignment layer) and a second substrate 980. Second substrate 980 may include a common LCD electrode layer formed thereon. In some implementations, second substrate 980 may include an alignment layer. In some implementations, color filters 960, 962, and 964 may be attached to second substrate 980 (e.g., in a black matrix attached to second substrate 980). An analyzer 990 (e.g., including a polarizer) may be positioned on second substrate 980 to filter the light modulated by liquid crystal material layer 970 to provide images with the desired color and intensity at each pixel.

[0112] FIG. 10 illustrates another example of an emissive LCD panel 1000 according to certain embodiments. Emissive LCD panel 1000 may be an example of emissive LCD panel 802 described above. As illustrated, emissive LCD panel 1000 may include color OLEDs 1030. 1032, and 1034 for providing color illumination light to an LC cell. Color OLEDs 1030, 1032, and 1034 may emit red, green, and blue light. Therefore, no color filters are needed in emissive LCD panel 1000. Color OLEDs 1030, 1032, and 1034 may be driven and controlled in groups or globally, rather than being controlled individually. For example, in some implementations, all color OLEDs 1030, 1032, and 1034 may be grouped together and be controlled by a same control circuit using a common anode and a common cathode. In some implementations, all color OLEDs 1030, 1032, and 1034 that emit light of the same color may be grouped together and be controlled by a same control circuit using a common anode and a common cathode. In some implementations, color OLEDs 1030, 1032, and 1034 in each respective region of a plurality of regions of emissive LCD panel 1000 may be grouped together and controlled by the same electrodes and control circuit, such that local dimming may be implemented in each respective region of the plurality of regions of emissive LCD panel 1000 to reduce power consumption. In some implementations, color OLEDs 1030, 1032, and 1034 may be divided based on their locations and the color of their emitted light, where color OLEDs 1030, 1032, and 1034 in each respective region and configured to emit light of the same color may be grouped to share a common anode and a common cathode and thus may be controlled together by a same control circuit, such that local dimming may be implemented.

[0113] In the example illustrated in FIG. 10, emissive LCD panel 1000 may include a first substrate 1010 (e.g., including a dielectric material such as glass) and LCD pixel drive circuits 1020 (e.g., TFT circuits) formed on first substrate 1010. A dielectric layer 1022 may be formed on LCD pixel drive circuits 1020 to encapsulate and electrically isolate LCD pixel drive circuits 1020. Dielectric layer 1022 may include, for example, SiCh, SiN, AI2O3, and the like, and may be thinned and planarized, for example, using CMP techniques, to form a thin encapsulation layer with a flat top surface. OLED drive circuits may also be implemented using TFT circuits formed on first substrate 1010.

[0114] Color OLEDs and their electrodes may then be formed on dielectric layer 1022. For example, a first OLED electrode layer 1024 (e.g., an anode layer) may be formed on dielectric layer 1022, color OLEDs 1030. 1032, and 1034 with multi-layer structures as described above may be formed on first OLED electrode layer 1024, and a second OLED electrode layer 1036 (e.g., a cathode layer) may be deposited on color OLEDs 1030, 1032, and 1034. Color OLEDs 1030, 1032, and 1034 may be configured to emit, for example, blue, green, and red light, respectively. First OLED electrode layer 1024 may include a conductive and reflective material, such as a metal or a metal alloy (e.g., Cu, Al, Ag, etc.), and may be used to reflect light emitted by OLEDs back towards the LC cell. In some embodiments, first OLED electrode layer 1024 may be patterned to form a plurality of groups of color OLEDs, where each group of color OLEDs may include color OLEDs in a respective region of a plurality of regions (e.g., a two-dimensional array of regions) and/or color OLEDs that emit light of a same color. Second OLED electrode layer 1036 may include a transparent conductive material, such as a TCO (e g., ITO). First OLED electrode layer 1024 and second OLED electrode layer 1036 may be connected to the OLED drive circuits formed on first substrate 1010 or outside of the active area.

[0115] Color OLEDs 1030, 1032, and 1034 may include, for example, thermally evaporated OLEDs or solution-processed OLEDs. Each color OLED may include, for example, a hole injection layer, a hole transport layer, an emissive layer, an electron transport layer, and an electron injection layer, where the multi-layer structure may be formed by processes such as spin coating, ultrasonic spray coating, blade coating, inkjet printing, and the like. In one implementation, color OLEDs that emit light of a first color (e.g., red) may be formed by forming a multi-layer structure configured to emit light of the first color and etching the multilayer structure to form individual color OLEDs for color subpixels. The color OLEDs that emit light of the first color may then be encapsulated, and color OLEDs that emit light of a second color (e.g., green) may be formed by forming multi-layer structures configured to emit light of the second color in the unencapsulated areas and etching the multi-layer structures to form individual color OLEDs for color subpixels. The color OLEDs that emit light of the second color may also be encapsulated after the etching, and color OLEDs that emit light of a third color (e.g., blue) may be formed by forming multi-layer structures configured to emit light of the third color in the unencapsulated areas.

[0116] A dielectric layer 1038 (e.g., including SiO2, SiN, AI2O3, etc.) may be deposited on second OLED electrode layer 1036 to encapsulate and electrically isolate the OLEDs and their electrodes. Dielectric layer 1038 may be used a substrate for the LC cell. Dielectric layer 1038 may be thinned and planarized (e.g., using CMP techniques) to form a thin encapsulation layer having a flat top surface. A first LCD pixel electrode layer 1040 may then be deposited on dielectric layer 1038, and may be patterned to form individual electrodes for individual LCD subpixels, where the individual electrodes may be connected to LCD pixel drive circuits 1020 through, for example, vias 1042. As second OLED electrode layer 1036, first LCD pixel electrode layer 1040 may also include a TCO such as ITO.

[0117] A polarizer layer 1050 may be coated on first LCD pixel electrode layer 1040 to form a polarizer (e.g., a bottom polarizer) for the LC cell. As described above, the polarizer may include a thin layer (e.g., less than about 1 pm) of a polymer polarizer. In some embodiments, polarizer layer 1050 may be formed on dielectric layer 1038, before depositing first LCD pixel electrode layer 1040. It is generally desirable that polarizer layer 1050 and dielectric layer 1038 are thin, such that light emitted from one color OLED 1030, 1032, or 1034 would not leak into the liquid crystal material layer 1060 on top of the adjacent color OLEDs to cause crosstalk between adjacent color subpixels and/or adjacent pixels. For example, it may be desirable for the total thickness of polarizer layer 1050 and dielectric layer 1038 to be no more than the pitch of the color OLEDs. Since polarizer layer 1050 can be made to be very thin (e.g., less than about 1 pm), the pitch of the color OLEDs can be small to achieve a high resolution.

[0118] Even though not shown in FIG. 10. a passivation layer and/or an alignment layer may be formed on polarizer layer 1050 to isolate LC materials and/or align the LC molecules in the LC materials. A liquid crystal material layer 1060 may be formed on polarizer layer 1050 (or the passivation and/or alignment layer). A second substrate 1070 may be on the liquid crystal material layer 1060 to sandwich liquid crystal material layer 1060 with the structure below liquid crystal material layer 1060. Second substrate 1070 may include a common LCD electrode layer formed thereon. In some implementations, second substrate 1070 may include an alignment layer. An analyzer 1080 (e.g., including a polarizer) may be positioned on second substrate 1070 to filter the light modulated by liquid cry stal material layer 1060 to provide images with desired color and intensity at each pixel.

[0119] As shown in FIGS. 9 and 10 described above, since no backlight unit is used and the in-cell polarizer can be made thin, the weight and thickness of the emissive LCD panels may be reduced. Furthermore, since the drive circuits (including the LCD pixel drive circuits and the global or group drive circuits for the OLEDs) may be implemented using TFT circuits on glass substrates, the emissive LCD panels can be large (and thus having large FOVs) and have low er costs. In addition, since backlight units below the LCD pixel drive circuits as used in existing transmissive LCD panels are not used in the emissive LCD panels disclosed herein, and the light emitters (e g., OLEDs) for illuminating the LC cell are between the LCD pixel drive circuits (e.g.. TFT circuits) and the LC cell, the emissive LCD panels disclosed herein do not have large inactive areas that may block illumination light and thus may not have high loss due to light blocked by the TFT circuits in the inactive areas as in existing transmissive LCD panels. Therefore, both the resolution and the power efficiency of the emissive LCD panels may be improved compared with existing transmissive LCD panels. When color OLEDs are used, the power efficiency and the brightness of the emissive LCD panels can be even higher because no color filters are used to filter the illumination light.

[0120] FIG. 11 includes a flowchart 1100 illustrating an example of a process of fabricating an emissive LCD panel according to certain embodiments. It is noted that the operations illustrated in FIG. 11 provide particular processes for fabricating emissive LCD panels described herein. Other sequences of operations can also be performed according to alternative embodiments. For example, alternative embodiments may perform the operations in a different order. Moreover, the individual operations illustrated in FIG. 11 can include multiple sub-operations that can be performed in various sequences as appropriate for the individual operation. Furthermore, some operations can be added or removed depending on the particular implementation. In some implementations, two or more operations may be performed in parallel. One of ordinary skill in the art would recognize many variations, modifications, and alternatives.

[0121] Operations in block 1110 of flowchart 1100 may include fabricating TFT drive circuits on a first substrate (e.g., a glass substrate). The TFT drive circuits may include LCD pixel drive circuits, and may also include drive circuits for controlling all OLEDs or groups of OLEDs of the emissive LCD panel. The TFT drive circuits may be fabricated on a glass substrate by a process including, for example, depositing (e.g., by sputtering) and patterning (e.g., by photolithography) gates (e.g., including a metal) on the glass substrate, depositing an insulator (e.g., including SiNx and/or SiCh), depositing an active layer (e.g., including low temperature polycrystalline (LTPS), hydrogenated amorphous silicon, amorphous indium- gallium-zinc oxide (a-IGZO), etc.), and depositing source and drain metal. The TFT drive circuit may be encapsulated with a dielectric layer (e.g., including SiNx, SiCh, or AI2O3), which may be thinned and planarized using, for example, a CMP process.

[0122] Operations in block 1120 may include forming OLEDs above the TFT drive circuits. In implementations that include white OLEDs as shown in FIG. 9. a first OLED electrode layer may be deposited and optionally patterned, a multi-layer OLED structure may be formed on the first OLED electrode layer, and a second OLED electrode layer may be deposited on the multi-layer OLED structure. The first OLED electrode layer may include a reflective conductive material (e.g., a metal or metal alloy such as Cu. Al. Ag, etc.). The multilayer OLED structure may include, for example, a hole injection layer, a hole transport layer, an emissive layer, an electron transport layer, and an electron injection layer. In some implementations, the multi-layer OLED structure may be formed by processes such as spin coating, ultrasonic spray coating, blade coating, inkjet printing, and the like. The second OLED electrode layer may include a TCO such as ITO.

[0123] In implementations that include color OLEDs as shown in FIG. 10, color OLEDs that emit light of a first color (e.g., red) may be formed by forming a multi-layer structure as described above and etching the multi-layer structure to form individual color OLEDs. The color OLEDs that emit light of the first color may then be encapsulated, and color OLEDs that emit light of a second color (e.g., green) may be formed by forming multi-layer structures in the unencapsulated areas as described above and etching the multi-layer structures to form individual color OLEDs. The color OLEDs that emit light of the second color may also be encapsulated after the etching, and color OLEDs that emit light of a third color (e.g., blue) may be formed by forming multi-layer structures in the unencapsulated areas. [0124] Operations in block 1130 may include forming transparent LCD subpixel electrodes above the OLEDs. In some implementations, before forming the transparent LCD pixel electrode, a dielectric encapsulation layer may be deposited the OLEDs and may be thinned and planarized to have a flat top surface using, for example, CMP. In some implementations, vias or other electrical connectors may be formed in the layers below to connect to the TFT drive circuits, and then a transparent LCD pixel electrode layer (e.g., include a TCO such as ITO) may be deposited and patented to form LCD subpixel electrodes that are electrically coupled to the TFT drive circuits.

[0125] Operations in block 1140 may include coating an in-cell polarizer layer after or before forming the transparent LCD subpixel electrodes. As described above, the in-cell polarizer layer may be formed using a polymer polarizer material that can be deposited by a coating process. The coated in-cell polarizer layer may have a thickness less than, for example, about 1 jam, to avoid crosstalk between adjacent color subpixels when the pitch of color OLEDs is small.

[0126] Operations in block 1150 may include completing the rest of LCD panel process to form, for example, an alignment layer, optional color filters, a LC material layer, a second LCD electrode layer, a cover substrate, and an analyzer (e.g., a polarizer), as described above with respect to, for example, FIGS. 6 and 7.

[0127] Embodiments disclosed herein may be used to implement components of an artificial reality system or may be implemented in conjunction with an artificial reality system. Artificial reality is a form of reality that has been adjusted in some manner before presentation to a user, which may include, for example, a virtual reality, an augmented reality, a mixed reality, a hybrid reality, or some combination and/or derivatives thereof. Artificial reality content may include completely generated content or generated content combined with captured (e.g., real-world) content. The artificial reality content may include video, audio, haptic feedback, or some combination thereof, and any of which may be presented in a single channel or in multiple channels (such as stereo video that produces a three-dimensional effect to the viewer). Additionally, in some embodiments, artificial reality may also be associated with applications, products, accessories, services, or some combination thereof, that are used to, for example, create content in an artificial reality and/or are otherwise used in (e.g., perform activities in) an artificial reality. The artificial reality⁷ system that provides the artificial realitycontent may be implemented on various platforms, including an HMD connected to a host computer system, a standalone HMD, a mobile device or computing system, or any other hardware platform capable of providing artificial reality content to one or more viewers.

[0128] FIG. 12 is a simplified block diagram of an example of an electronic system 1200 of an example near-eye display (e.g., HMD device) for implementing some examples disclosed herein. Electronic system 1200 may be used as the electronic system of an HMD device or other near-eye displays described above. In this example, electronic system 1200 may include one or more processor(s) 1210 and a memory 1220. Processor(s) 1210 may be configured to execute instructions for performing operations at a number of components, and can be. for example, a general-purpose processor or microprocessor suitable for implementation within a portable electronic device. Processor(s) 1210 may be communicatively coupled with a plurality of components within electronic system 1200. To realize this communicative coupling, processor(s) 1210 may communicate with the other illustrated components across a bus 1240. Bus 1240 may be any subsystem adapted to transfer data within electronic system 1200. Bus 1240 may include a plurality of computer buses and additional circuitry to transfer data.

[0129] Memory 1220 may be coupled to processor(s) 1210. In some embodiments, memory 1220 may offer both short-term and long-term storage and may be divided into several units. Memory 1220 may be volatile, such as static random access memory (SRAM) and/or dynamic random access memory (DRAM) and/or non-volatile, such as read-only memory (ROM), flash memory. and the like. Furthermore, memory⁷ 1220 may include removable storage devices, such as secure digital (SD) cards. Memory 1220 may provide storage of computer-readable instructions, data structures, program code, and other data for electronic system 1200. In some embodiments, memory 1220 may be distributed into different hardware subsystems. A set of instructions and/or code might be stored on memory⁷ 1220. The instructions might take the form of executable code that may be executable by electronic system 1200, and/or might take the form of source and/or installable code, which, upon compilation and/or installation on electronic system 1200 e.g., using any of a variety of generally⁷ available compilers, installation programs, compression/decompression utilities, etc.), may take the form of executable code.

[0130] In some embodiments, memory 1220 may store a plurality of applications 1222 through 1224, which may include any number of applications. Examples of applications may include gaming applications, conferencing applications, video playback applications, or other suitable applications. The applications may include a depth sensing function or eye tracking function. Applications 1222-1224 may include particular instructions to be executed by processor(s) 1210. In some embodiments, certain applications or parts of applications 1222- 1224 may be executable by other hardware subsystems 1280. In certain embodiments, memory 1220 may additionally include secure memory, which may include additional security' controls to prevent copying or other unauthorized access to secure information.

[0131] In some embodiments, memory 1220 may include an operating system 1225 loaded therein. Operating system 1225 may be operable to initiate the execution of the instructions provided by applications 1222-1224 and/or manage other hardware subsystems 1280 as well as interfaces with a wireless communication subsystem 1230 which may include one or more wireless transceivers. Operating system 1225 may be adapted to perform other operations across the components of electronic system 1200 including threading, resource management, data storage control and other similar functionality⁷.

[0132] Wireless communication subsystem 1230 may include, for example, an infrared communication device, a wireless communication device and/or chipset (such as a Bluetooth® device, an IEEE 802.11 device, a Wi-Fi device, a WiMax device, cellular communication facilities, etc.), and/or similar communication interfaces. Electronic system 1200 may include one or more antennas 1234 for wireless communication as part of wireless communication subsystem 1230 or as a separate component coupled to any portion of the system. Depending on desired functionality, wireless communication subsystem 1230 may include separate transceivers to communicate with base transceiver stations and other wireless devices and access points, which may include communicating with different data networks and/or network types, such as wireless wide-area networks (WWANs), wireless local area networks (WLANs), or wireless personal area networks (WP ANs). A WWAN may be, for example, a WiMax (IEEE 802.16) network. A WLAN may be, for example, an IEEE 802.1 lx network. A WPAN may be, for example, a Bluetooth network, an IEEE 802.15x, or some other types of network. The techniques described herein may also be used for any combination of WWAN, WLAN, and/or WPAN. Wireless communications subsystem 1230 may permit data to be exchanged with a network, other computer systems, and/or any other devices described herein. Wireless communication subsystem 1230 may include a means for transmitting or receiving data, such as identifiers of HMD devices, position data, a geographic map, a heat map, photos, or videos, using antenna(s) 1234 and wireless link(s) 1232.

[0133] Embodiments of electronic system 1200 may also include one or more sensors 1290. Sensor(s) 1290 may include, for example, an image sensor, an accelerometer, a pressure sensor, a temperature sensor, a proximity sensor, a magnetometer, a gyroscope, an inertial sensor (e g., a subsystem that combines an accelerometer and a gyroscope), an ambient light sensor, or any other similar devices or subsystems operable to provide sensory output and/or receive sensory input, such as a depth sensor or a position sensor. For example, in some implementations, sensor(s) 1290 may include one or more inertial measurement units (IMUs) and/or one or more position sensors. An IMU may generate calibration data indicating an estimated position of the HMD device relative to an initial position of the HMD device, based on measurement signals received from one or more of the position sensors. A position sensor may generate one or more measurement signals in response to motion of the HMD device. Examples of the position sensors may include, but are not limited to, one or more accelerometers, one or more gyroscopes, one or more magnetometers, another suitable type of sensor that detects motion, a type of sensor used for error correction of the IMU, or some combination thereof. The position sensors may be located external to the IMU, internal to the IMU. or some combination thereof. At least some sensors may use a structured light pattern for sensing.

[0134] Electronic system 1200 may include a display 1260. Display 1260 may be a neareye display, and may graphically present information, such as images, videos, and various instructions, from electronic system 1200 to a user. Such information may be derived from one or more applications 1222-1224, virtual reality engine 1226. one or more other hardware subsystems 1280, a combination thereof, or any other suitable means for resolving graphical content for the user (e.g., by operating system 1225). Display 1260 may use liquid crystal display (LCD) technology⁷, light-emitting diode (LED) technology (including, for example, OLED. ILED, pLED. AMOLED, TOLED. etc.), light emitting polymer display (LPD) technology, or some other display technology.

[0135] Electronic system 1200 may include a user input/output interface 1270. User input/output interface 1270 may allow a user to send action requests to electronic system 1200. An action request may be a request to perform a particular action. For example, an action request may be to start or end an application or to perform a particular action within the application. User input/output interface 1270 may include one or more input devices. Example input devices may include a touchscreen, a touch pad, microphone(s), button(s), dial(s), switch(es), a keyboard, a mouse, a game controller, or any other suitable device for receiving action requests and communicating the received action requests to electronic system 1200. In some embodiments, user input/output interface 1270 may provide haptic feedback to the user in accordance with instructions received from electronic system 1200. For example, the haptic feedback may be provided when an action request is received or has been performed.

[0136] Electronic system 1200 may include a camera 1250 that may be used to take photos or videos of a user, for example, for tracking the user’s eye position. Camera 1250 may also be used to take photos or videos of the environment, for example, for VR, AR, or MR applications. Camera 1250 may include, for example, a complementary metal-oxide-semiconductor (CMOS) image sensor with a few millions or tens of millions of pixels. In some implementations, camera 1250 may include two or more cameras that may be used to capture 3-D images.

[0137] In some embodiments, electronic system 1200 may include a plurality of other hardware subsystems 1280. Each of other hardware subsystems 1280 may be a physical subsystem within electronic system 1200. While each of other hardware subsystems 1280 may be permanently configured as a structure, some of other hardware subsystems 1280 may be temporarily configured to perform specific functions or temporarily activated. Examples of other hardware subsystems 1280 may include, for example, an audio output and/or input interface (e.g. a microphone or speaker), a near field communication (NFC) device, a rechargeable battery, a battery management system, a wired/wireless battery charging system, etc. In some embodiments, one or more functions of other hardware subsystems 1280 may be implemented in software.

[0138] In some embodiments, memory 1220 of electronic system 1200 may also store a virtual reality engine 1226. Virtual reality engine 1226 may execute applications within electronic system 1200 and receive position information, acceleration information, velocity⁷ information, predicted future positions, or some combination thereof of the HMD device from the various sensors. In some embodiments, the information received by virtual reality engine 1226 may be used for producing a signal (e.g., display instructions) to display 1260. For example, if the received information indicates that the user has looked to the left, virtual reality engine 1226 may generate content for the HMD device that mirrors the user's movement in a virtual environment. Additionally, virtual reality engine 1226 may perform an action within an application in response to an action request received from user input/output interface 1270 and provide feedback to the user. The provided feedback may be visual, audible, or haptic feedback. In some implementations, processor(s) 1210 may include one or more GPUs that may execute virtual reality engine 1226.

[0139] In various implementations, the above-described hardware and subsystems may be implemented on a single device or on multiple devices that can communicate with one another using wired or wireless connections. For example, in some implementations, some components or subsystems, such as GPUs, virtual reality engine 1226, and applications (c.g.. tracking application), may be implemented on a console separate from the head-mounted display device. In some implementations, one console may be connected to or support more than one HMD. [0140] In alternative configurations, different and/or additional components may be included in electronic system 1200. Similarly, functionality of one or more of the components can be distributed among the components in a manner different from the manner described above. For example, in some embodiments, electronic system 1200 may be modified to include other system environments, such as an AR system environment and/or an MR environment.

[0141] The methods, systems, and devices discussed above are examples. Various embodiments may omit, substitute, or add various procedures or components as appropriate. For instance, in alternative configurations, the methods described may be performed in an order different from that described, and/or various stages may be added, omitted, and/or combined. Also, features described with respect to certain embodiments may be combined in various other embodiments. Different aspects and elements of the embodiments may be combined in a similar manner. Also, technology evolves and, thus, many of the elements are examples that do not limit the scope of the disclosure to those specific examples.

[0142] Specific details are given in the description to provide a thorough understanding of the embodiments. However, embodiments may be practiced without these specific details. For example, well-known circuits, processes, systems, structures, and techniques have been shown without unnecessary detail in order to avoid obscuring the embodiments. This description provides example embodiments only, and is not intended to limit the scope, applicability, or configuration of the invention. Rather, the preceding description of the embodiments will provide those skilled in the art with an enabling description for implementing various embodiments. Various changes may be made in the function and arrangement of elements without departing from the scope of the present disclosure.

[0143] Also, some embodiments were described as processes depicted as flow diagrams or block diagrams. Although each may describe the operations as a sequential process, many of the operations may be performed in parallel or concurrently. In addition, the order of the operations may be rearranged. A process may have additional steps not included in the figure. Furthermore, embodiments of the methods may be implemented by hardware, software, firmware, middleware, microcode, hardware description languages, or any combination thereof. When implemented in software, firmware, middleware, or microcode, the program code or code segments to perform the associated tasks may be stored in a computer-readable medium such as a storage medium. Processors may perform the associated tasks.

[0144] It will be apparent to those skilled in the art that substantial variations may be made in accordance with specific requirements. For example, customized or special-purpose hardware might also be used, and/or particular elements might be implemented in hardware, software (including portable software, such as applets, etc.), or both. Further, connection to other computing devices such as network input/output devices may be employed.

[0145] With reference to the appended figures, components that can include memory can include non-transitory machine-readable media. The term “machine-readable medium” and “computer-readable medium” may refer to any storage medium that participates in providing data that causes a machine to operate in a specific fashion. In embodiments provided hereinabove, various machine-readable media might be involved in providing instructions/ code to processing units and/or other device(s) for execution. Additionally or alternatively, the machine-readable media might be used to store and/or carry such instructions/code. In many implementations, a computer-readable medium is a physical and/or tangible storage medium. Such a medium may take many forms, including, but not limited to, non-volatile media, volatile media, and transmission media. Common forms of computer-readable media include, for example, magnetic and/or optical media such as compact disk (CD) or digital versatile disk (DVD), punch cards, paper tape, any other physical medium with patterns of holes, a RAM, a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), a FLASH-EPROM, any other memory chip or cartridge, a carrier wave as described hereinafter, or any other medium from which a computer can read instructions and/or code. A computer program product may include code and/or machine-executable instructions that may represent a procedure, a function, a subprogram, a program, a routine, an application (App), a subroutine, a module, a software package, a class, or any combination of instructions, data structures, or program statements.

[0146] Those of skill in the art will appreciate that information and signals used to communicate the messages described herein may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by' voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0147] Terms “and” and “or,” as used herein, may include a variety of meanings that are also expected to depend at least in part upon the context in which such terms are used. Typically, “or” if used to associate a list, such as A, B, or C, is intended to mean A, B, and C, here used in the inclusive sense, as well as A, B, or C, here used in the exclusive sense. In addition, the term “one or more” as used herein may be used to describe any feature, structure, or characteristic in the singular or may be used to describe some combination of features, structures, or characteristics. However, it should be noted that this is merely an illustrative example and claimed subject matter is not limited to this example. Furthermore, the term “at least one of’ if used to associate a list, such as A, B, or C, can be interpreted to mean A, B, C, or any combination of A, B, and/or C, such as AB, AC, BC, AA, ABC, AAB, AABBCCC, or the like.

[0148] In this description, the recitation “based on” means “based at least in part on.” Therefore, if X is based on Y, then X may be a function of at least a part of Y and any number of other factors. If an action X is "based on" Y, then the action X may be based at least in part on at least a part of Y.

[0149] Further, while certain embodiments have been described using a particular combination of hardware and software, it should be recognized that other combinations of hardware and software are also possible. Certain embodiments may be implemented only in hardware, or only in software, or using combinations thereof. In one example, software may be implemented with a computer program product containing computer program code or instructions executable by one or more processors for performing any or all of the steps, operations, or processes described in this disclosure, where the computer program may be stored on anon-transitory computer readable medium. The various processes described herein can be implemented on the same processor or different processors in any combination.

[0150] Where devices, systems, components or modules are described as being configured to perform certain operations or functions, such configuration can be accomplished, for example, by designing electronic circuits to perform the operation, by programming programmable electronic circuits (such as microprocessors) to perform the operation such as by executing computer instructions or code, or processors or cores programmed to execute code or instructions stored on a non-transitory memory medium, or any combination thereof. Processes can communicate using a variety of techniques, including, but not limited to, conventional techniques for inter-process communications, and different pairs of processes may use different techniques, or the same pair of processes may use different techniques at different times.

[0151] The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense. It will, however, be evident that additions, subtractions, deletions, and other modifications and changes may be made thereunto without departing from the scope as set forth in the claims. Thus, although specific embodiments have been described, these are not intended to be limiting. Various modifications and equivalents are within the scope of the following claims.

Claims

WHAT IS CLAIMED IS:

1. An emissive liquid crystal display (LCD) panel comprising: a first substrate including thin-film transistor (TFT) drive circuits formed thereon; a liquid crystal (LC) cell including LCD pixel electrodes electrically coupled to the TFT drive circuits; and one or more light emitters between the TFT drive circuits and the LC cell and configured to illuminate the LC cell.

2. The emissive LCD panel of claim 1, wherein the first substrate includes a glass substrate.

3. The emissive LCD panel of claim 1 or 2. wherein: the one or more light emitters include one or more white light emitting organic light emitting diodes (OLEDs); and the LC cell includes an array of color filters; or wherein the one or more light emitters include an array of OLEDs configured to emit light of multiple colors.

4. The emissive LCD panel of any one of the preceding claims, wherein the one or more light emitters share a common anode and a common cathode.

5. The emissive LCD panel of any one of the preceding claims, wherein the TFT drive circuits include LCD pixel drive circuits and drive circuits for driving the one or more light emitters globally.

6. The emissive LCD panel of any one of the preceding claims, wherein the one or more light emitters are divided into a plurality of groups, light emitters in each group of the plurality⁷ of groups located in a respective region of a plurality of regions of the emissive LCD panel and sharing a common anode and a common cathode.

7. The emissive LCD panel of claim 6, wherein the TFT drive circuits include LCD pixel drive circuits and respective drive circuits for driving each group of light emitters of the plurality of groups; preferably wherein the respective drive circuits for driving each group of light emitters of the plurality of groups are configurable to locally dim the group of light emitters in the plurality of groups.

8. The emissive LCD panel of any one of the preceding claims, wherein the LC cell includes: an LC material layer; and an in-cell polarizer between the LC material layer and the one or more light emitters.

9. The emissive LCD panel of claim 8, wherein the in-cell polarizer includes a polymer polarizer; and/or wherein the in-cell polarizer is characterized by a thickness less than 2 jam.

10. The emissive LCD panel of any one of the preceding claims, further comprising a planarized encapsulation layer between the one or more light emitters and the LC cell.

11. The emissive LCD panel of any one of the preceding claims, wherein the LCD pixel electrodes are electrically coupled to the TFT drive circuits through electrical connectors that pass through the one or more light emitters.

12. The emissive LCD panel of any one of the preceding claims, wherein the emissive LCD panel is characterized by a resolution greater than 1000 pixels per inch; and/or wherein the emissive LCD panel is characterized by an active area greater than 1.5x 1.5 square inches.

13. A near-eye display system comprising: an emissive liquid crystal display (LCD) panel comprising: a first substrate including thin-film transistor (TFT) drive circuits formed thereon; a liquid crystal (LC) cell including LCD pixel electrodes electrically coupled to the TFT drive circuits; and one or more light emitters between the TFT drive circuits and the LC cell and configured to illuminate the LC cell; and display optics configured to project images displayed by the emissive LCD panel to an eye of a user of the near-eye display system.

14. The near-eye display system of claim 13, wherein: the first substrate includes a glass substrate; the one or more light emitters include one or more organic light emitting diodes (OLEDs); and the emissive LCD panel is characterized by an active area greater than 1.5x1.5 square inches; preferably wherein the one or more OLEDs includes white light emitting OLEDs or color light emitting OLEDs.

15. The near-eye display system of claim 13 or 14, wherein: the one or more light emitters are divided into a plurality of groups, wherein light emitters in each group of the plurality of groups are in a respective region of a plurality’ of regions of the emissive LCD panel and share a common anode and a common cathode; and the TFT drive circuits include respective drive circuits for driving each group of light emitters of the plurality of groups and configurable to locally dim the group of light emitters in the plurality of groups.