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WO2025061401A1 - Dispositif d'affichage pour détection de lumière ambiante et ses procédés de fonctionnement et de fabrication - Google Patents

Dispositif d'affichage pour détection de lumière ambiante et ses procédés de fonctionnement et de fabrication Download PDF

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Publication number
WO2025061401A1
WO2025061401A1 PCT/EP2024/073320 EP2024073320W WO2025061401A1 WO 2025061401 A1 WO2025061401 A1 WO 2025061401A1 EP 2024073320 W EP2024073320 W EP 2024073320W WO 2025061401 A1 WO2025061401 A1 WO 2025061401A1
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WO
WIPO (PCT)
Prior art keywords
sensor
light
display device
display
filter
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/EP2024/073320
Other languages
English (en)
Inventor
Johannes Haase
Jean-Jacques Drolet
Antoine BONIFACE
Rainer Minixhofer
Stephan Janka
Georg ROSSBACH
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ams Osram International GmbH
Original Assignee
Ams Osram International GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ams Osram International GmbH filed Critical Ams Osram International GmbH
Publication of WO2025061401A1 publication Critical patent/WO2025061401A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
    • G09G3/30—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
    • G09G3/32—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/2007—Display of intermediate tones
    • G09G3/2014—Display of intermediate tones by modulation of the duration of a single pulse during which the logic level remains constant
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2300/00—Aspects of the constitution of display devices
    • G09G2300/04—Structural and physical details of display devices
    • G09G2300/0439—Pixel structures
    • G09G2300/0452—Details of colour pixel setup, e.g. pixel composed of a red, a blue and two green components
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2310/00—Command of the display device
    • G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
    • G09G2310/0243—Details of the generation of driving signals
    • G09G2310/0254—Control of polarity reversal in general, other than for liquid crystal displays
    • G09G2310/0256—Control of polarity reversal in general, other than for liquid crystal displays with the purpose of reversing the voltage across a light emitting or modulating element within a pixel
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/06—Adjustment of display parameters
    • G09G2320/0626—Adjustment of display parameters for control of overall brightness
    • G09G2320/064—Adjustment of display parameters for control of overall brightness by time modulation of the brightness of the illumination source
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2360/00—Aspects of the architecture of display systems
    • G09G2360/14—Detecting light within display terminals, e.g. using a single or a plurality of photosensors
    • G09G2360/144—Detecting light within display terminals, e.g. using a single or a plurality of photosensors the light being ambient light

Definitions

  • a display device, a method of operating a display device and a method of manufacturing a display device are specified.
  • Displays in particular micro-LED displays, have many metal layers to fan out the driver signal to the emitters. They are therefore not very transparent, so that behind display sensing technologies cannot be used as in e.g. OLED displays.
  • An ambient light sensor, ALS can be arranged outside the display, e.g. at a notch of the display.
  • At least one object of particular embodiments is to provide in-display sensing.
  • a display device is provided .
  • the display device comprises a display.
  • the display device is or is integrated in a touch screen, a smartwatch, a smartphone, a tablet, a dashboard, an automotive dashboard.
  • the display device comprises a substrate comprising a main surface .
  • the substrate may also be called carrier or backplane .
  • the substrate is implemented as silicon backplane or as flex-plane .
  • the substrate can be or can comprise a foil , for instance .
  • the substrate can be rigid or flexible .
  • the substrate has a main plane of extension .
  • lateral directions refer to directions that run parallel to the main plane of extension .
  • the vertical direction refers to a direction that runs perpendicular to the main plane of extension .
  • the main surface of the substrate is parallel to the main plane of extension of the substrate .
  • the display device comprises a plurality of emitters arranged in pixels on the main surface of the substrate .
  • the emitters are arranged in groups .
  • the pixels may form rectangular or square regions on the main surface of the substrate , wherein said regions are adj acent to each other .
  • the pixels form the display of the display device .
  • Each pixel can comprise one or more emitters .
  • each pixel can comprise wirings to electrically connect the emitters .
  • the pixels and/or the emitters in the pixels can be operated individually or in groups . That the emitters are arranged on the main surface of the substrate can mean that they are mounted on the main surface . This can mean that they are not integrated or embedded in the substrate . For example , they are attached to the substrate by means of a trans fer process , in particular a mass trans fer process, by which a plurality of emitters are attached to the substrate simultaneously.
  • each emitter comprises a light emitting diode, LED, that is configured to emit light during operation.
  • each emitter is for example configured to emit electromagnetic radiation in a main emission direction during intended operation.
  • the main emission direction is preferably oriented perpendicular to the main surface of the substrate.
  • each emitter is configured to emit electromagnetic radiation having a main wavelength in the spectral region visible to the human eye, i.e. between 380 nm and 750 nm.
  • Different emitters may emit light in different wavelength ranges.
  • Each pixel may comprise one or more emitters, thus one or more LEDs.
  • Each pixel may comprise at least three LEDs (e.g. red, green, blue) for covering the visible wavelength range.
  • Each pixel may also comprise more than three LEDs to provide a certain degree of redundancy and/or additional functionality.
  • the display device comprises a sensor in at least one pixel, the sensor being configured to sense light during operation.
  • the display device comprises at least one sensor.
  • at least one pixel of the plurality of pixels in the display device comprises a sensor.
  • said pixel comprises only the sensor or the sensor in addition to one or more emitters.
  • said pixel comprises the sensor and at least three emitters to cover the visible wavelength range.
  • That the sensor is configured to sense light during operation can mean that the sensor is configured to sense ambient light, but not display light, i.e. light emitted by the emitters.
  • the sensor may be sensitive to a particular wavelength range in the visible spectrum.
  • the sensor can have a viewing angle. In particular, the viewing angle includes the vertical direction, such that the sensor is a "top-looking" sensor.
  • the field of illumination of the emitters and the field of view of the sensor may at least overlap.
  • the display device may comprise more than one sensor that are distributed in respective pixels of the display device. It is also possible that more than one sensor is arranged in a single pixel. In case of two or more sensors in the display device the sensors can be sensitive to light in different wavelength ranges.
  • the display device comprises a filter.
  • the filter is arranged on or above the sensor.
  • the filter is configured to transmit light of a predetermined wavelength range to the sensor.
  • the filter can be referred to as wavelength filter.
  • the filter is arranged in the vertical direction on or above the sensor. If the display device comprises more than one sensor, each sensor can be provided with a respective filter. In this case, the filters can be different, such that light of different wavelength ranges is transmitted to the sensor assigned to the respective filter.
  • the filter is configured to filter light, in particular ambient light, before it hits the sensor. This can mean that only a portion of ambient light, in particular the portion corresponding to the predetermined wavelength range, reaches the sensor. Light of wavelengths outside the predetermined wavelength range is prevented from reaching the sensor .
  • a display device comprises a substrate comprising a main surface . It further comprises a plurality of emitters arranged in pixels on the main surface of the substrate , wherein each emitter comprises a light emitting diode , LED, that is configured to emit light during operation . It further comprises a sensor in at least one pixel , the sensor being configured to sense light during operation . It further comprises a filter arranged on or above the sensor, the filter being configured to transmit light of a predetermined wavelength range to the sensor .
  • the display device described here is based on the following considerations , among others .
  • Displays in particular micro-LED displays , have many metal layers to fan out the driver signal to the emitters . They are therefore not very transparent and behind display sensing technologies cannot be used as in e . g . OLED displays . It is therefore beneficial to use in-display sensing technology, where the sensor is embedded and integrated into the display such that no display notch is needed . In other words , integrating the sensor into the display removes any notches from the display without the need to enable behind display sensing .
  • the sensor can be embedded into the display .
  • the sensor can be used for wavelength dependent ambient light sensing, ALS .
  • ALS wavelength dependent ambient light sensing
  • the display can be partially or entirely populated with the additional sensors .
  • a distributed ambient light sensor is formed . While a localized ambient light sensor does not work when it is covered, a distributed (delocalized) in-display sensor has redundancies and can also work when the display (e.g. of a smartphone) is partially covered.
  • Sensing can be synchronized to the pulse width modulation (PWM) of the emitter LEDs to prevent backscattered display light from being sensed. This allows to distinguish between ambient light and display light.
  • PWM pulse width modulation
  • In-display wavelength dependent sensing is provided. Possible applications are auto white balance, AWB, for camera, AWB for display, spectral sensing and/or ambient light sensing, ALS . In particular, it is possible to manage and calibrate display color appearance (auto white balance) locally and directly.
  • each emitter is formed by a micro-LED.
  • a micro-LED could be seen as any light emitting diode (LED) - generally not a laser - with a particularly small size.
  • LED light emitting diode
  • a growth substrate is removed from micro-LEDs, so that typical heights of such micro-LEDs are in the range of 0.5 pm to 10 pm, for example.
  • a micro-LED does not necessarily have to have a rectangular radiation emission surface.
  • an LED could have a radiation emission surface in which, in plan view of the layers of the layer stack, any lateral extent of the radiation emission surface is less than or equal to 100 pm or less than or equal to 70 pm.
  • micro-LEDs For example, in the case of rectangular micro-LEDs, an edge length - especially in plan view of the layers of the layer stack - smaller than or equal to 70 qm or smaller than or equal to 50 qm is often cited as a criterion .
  • micro-LEDs are provided on wafers with - for the qLED nondestructive ⁇ - detachable holding structures .
  • micro-LEDs are mainly used in displays .
  • the micro-LEDs form pixels or subpixels and emit light of a defined color . Small pixel si ze and a high density with close distances make micro-LEDs suitable , among others , for small monolithic displays for AR applications , especially data glasses .
  • the pixels are formed as RGB-pixels , in which a first emitter configured to emit red light , a second emitter configured to emit green light , and a third emitter configured to emit blue light are arranged .
  • each emitter is intended to emit radiation of a di f ferent main wavelength .
  • a main wavelength is to be understood as a wavelength in an emission spectrum where the intensity reaches a global maximum .
  • a first emitter is intended to emit radiation of a red color
  • a second emitter is intended to emit radiation of a green color
  • a third emitter is intended to emit radiation of a blue color in its intended operation .
  • Such a red, green, blue ( short : RGB ) arrangement is especially suitable for a pixel of a display device .
  • Red light may refer to light in a wavelength range from 640 nm to 780 nm, for example .
  • Green light may refer to light in a wavelength range from 490 nm to 570 nm, for example.
  • Blue light may refer to light in a wavelength range from 430 nm to 490 nm.
  • the entire visible spectrum is covered by additive color mixing of the three components R, G and B.
  • the emitters may be formed by respective LEDs, in particular micro-LEDs.
  • each pixel is formed as an RGB-pixel comprising a red light emitter, a green light emitter and a blue light emitter.
  • the pixel can also comprise more than one emitter for each color, for example to provide a certain degree of redundancy.
  • the senor is formed as a photodiode, wherein the photodiode is embedded in the substrate .
  • the photodiode, PD is integrated in the substrate and/or formed in the substrate.
  • the photodiode is an embedded photodiode.
  • the photodiode can be a silicon photodiode, but other material are also possible.
  • the silicon photodiode can have a larger size in lateral directions and can be thicker than the emitters. Silicon photodiodes are suitable to detect visible light.
  • the substrate on which the emitters are arranged thus has additional sensing capabilities.
  • the emitters can be arranged on regions of the substrate outside the photodiode ( s ) .
  • the photodiode is arranged on the main surface of the substrate next to the emitters .
  • Such a photodiode can form a separate detector chip .
  • the photodiode can be a micro-PD .
  • This can mean that the photodiode has a similar si ze as each of the emitters , in particular i f they are formed as micro-LEDs . It is also possible that the photodiode has a larger si ze for ef ficiency reasons .
  • I f the photodiode is arranged on the substrate its thickness can preferably be similar or equal to the thickness of the emitters .
  • That the photodiode is arranged on the substrate can mean that it is mounted on the substrate , for example by means of a (mass- ) trans fer process .
  • That the photodiode is arranged next to the emitters can mean that the photodiode and the emitters are arranged in a common pixel .
  • the senor is implemented as an LED, in particular micro-LED that is arranged on the main surface of the substrate next to the emitters and configured to be biased for sensing a photocurrent .
  • the sensor is implemented as (micro- ) LED can mean that the sensor and the emitters have a same or similar structure .
  • the sensor and the emitters may be formed by a common semiconductor layer stack .
  • the sensor can emit light when appropriately biased, in particular i f the sensor is forward biased .
  • i f the sensor is zero biased or reverse biased, it is configured to sense a photocurrent depending on light hitting the sensor .
  • the external quantum ef ficiency, EQE of red, green and blue light emitting micro-LEDs in reverse or zero bias reach values above 20% depending on the wavelength to be detected .
  • red, green/blue light emitting micro-LEDs used in combination as sensors span the entire visible spectrum .
  • the EQE curves of the blue or green and the red micro-LED match together to span the visible wavelength range .
  • additional red or blue/green micro-LEDs can be placed in some or all pixels for sensing .
  • the pixels may comprise additional (micro- ) LEDs for redundancy reasons anyway .
  • These additional emitters can be used as sensors , thus reducing complexity of the manufacturing process .
  • the (micro- ) LEDs can be operated and biased depending on whether they are used as emitters or as sensors . Dynamic use as emitter and sensor is also possible . This means that an emitter can be used as sensor by dynamically changing its electrical bias , e . g . by integrating a multiplexer in the driving circuit .
  • Biasing LEDs for sensing a photocurrent represents a simple and cost-ef ficient solution to provide sensing capabilities of a display device . By using reverse or zero biases micro-LEDs additional components other than display components are not required .
  • the emitters and the sensor are manufactured according to a common manufacturing process .
  • both the emitters and the sensor are formed as (micro- ) LEDs .
  • the emitters and the sensor can be fabricated on a common carrier substrate . They can simultaneously be trans ferred to the substrate of the display device . Therefore , fabrication of the display device is facilitated and costs are reduced . It is also possible to trans fer all display LEDs with double density for redundancy to avoid broken LED repair . LEDs that are not used for emitting light but are functional can be used for sensing . This would mean that the sensor has a coverage of less than 100% but could still have a satis factory functionality .
  • the display device comprises a plurality of sensors being configured to sense light during operation, wherein the sensors are distributed over the display in respective pixels of the display device , and wherein each sensor is provided with a respective filter configured to transmit light of a predetermined wavelength range to the sensor .
  • each pixel comprises at least one sensor .
  • each second or each third pixel comprises a sensor .
  • the sensors are evenly distributed .
  • the sensors can be the same or di f ferent . That the sensors are di f ferent can mean that their sensitivities for particular wavelengths di f fer from each other .
  • the sensors can have same or similar sensitivities for particular wavelength ranges .
  • the respective filters assigned to each sensor can be the same or di f ferent . This can mean that the filters transmit light in a same or in a di f ferent wavelength range. In particular, at least some of the filters are the same. In particular, at least some of the filters are different.
  • the plurality of sensors arranged in respective pixels form a distributed spectral sensor that has more redundancies than a local sensor (e.g. at a notch of the display or a dedicated area behind the display) . Further, it is less sensitive to disturbances, e.g. covering the sensor by hairs, fingers, dirt or dust. Integrating the spectral sensor into the display removes any notches from the display without the need to be behind the display like e.g. behind OLED sensing. As the sensors are distributed over the display, the distributed spectral sensor has a 2D spatial resolution .
  • different spectral channels are formed by the plurality of sensors and filters, wherein each spectral channel is sensitive for a respective wavelength range.
  • the display device comprises a plurality of spectral channels.
  • a particular spectral channel is formed by sensorfilter pairs that are configured for sensing light in a particular wavelength range. Combinations of different sensors and filters lead to a plurality of different spectral channels and therefore to a distributed spectral sensor of the display device.
  • At least one spectral channel is placed over the display with a density different from a density of at least one other spectral channel.
  • the individual channels can be placed with different density to tune or equalize the overall spectral response of the channels. For example, to compensate for a first channel having lower sensing efficiency than a second channel, more sensor-filter pairs forming the first channel can be placed in the display than sensor-filter pairs forming the second channel. In other words, the difference in EQE on the different color channels can be made up by placing more sensors of low sensitivity channels and less of high sensitivity channels.
  • sensors of at least one spectral channel are driven with an amplification gain different from an amplification gain of sensors of at least one other spectral channel.
  • the channels, in particular the respective sensors, can be driven with different amplification gains to tune or equalize the overall spectral response of the channels.
  • pixels of a first group comprise a respective sensor that is formed as blue or green micro-LED and configured to be biased for sensing a photocurrent .
  • pixels of a second group comprise a respective sensor that is formed as red micro-LED and configured to be biased for sensing a photocurrent .
  • pixels comprise both blue/green and red micro-LEDs used as sensors.
  • the display device comprises red, blue and/or green micro-LEDs used as sensors.
  • Blue, green and red micro-LEDs refer to micro-LEDs that emit light in the blue, green and red wavelength range, respectively, if they are operated in forward bias. It has been found that the external quantum ef ficiency, EQE , of red, green and blue light emitting micro-LEDs in reverse or zero bias reach values above 20% depending on the wavelength to be detected .
  • Blue and green micro-LEDs cover a wavelength range from about 350 nm to 500 nm, while red micro-LEDs cover a wavelength range from about 450 nm to 650 nm .
  • the display device can use both red and blue/green micro-LEDs as sensors to cover the full visible spectrum .
  • the filter is implemented as interference filter or as color filter .
  • Interference filters comprise several layers of materials with di f ferent refractive indices and thicknesses . The selection of these materials makes it possible to transmit or block certain wavelengths of light by using the interference of light waves .
  • the interference filter comprise a stack of dielectric and/or metallic layers .
  • the filter may comprise glass , plastics or resin, by way of example , in order to selectively transmit speci fic wavelengths of light and block others .
  • the filter is arranged on the sensor .
  • the display device further comprises a transparent cover covering the pixels.
  • the cover is transparent for visible light.
  • the cover comprises glass or a transparent plastic material.
  • the cover can be arranged directly above the emitters and the sensor (s) . It is also possible that the cover has a distance to the emitters and the sensor (s) .
  • the cover protects the emitter and the sensors (s) . Further, the cover may provide additional functionality, it may be formed as touch screen, for example.
  • the filter is arranged on the cover.
  • the filter is attached to, mounted to or structured on the cover.
  • the filter can be arranged on a side of the cover that faces the sensor or on a side that faces away from the sensor. It is also possible that the filter is integrally formed with the cover. Thus, it is possible to align the filter (s) with the respective sensor on or in the substrate.
  • the sensor does not need to be further processed, e.g. by depositing and structuring filter layers on it. By placing the filter onto the cover no filter structuring on the display components itself is required.
  • the display device further comprises a control circuit.
  • control circuit is integrated in the substrate. It is however also possible that the control circuit is arranged on the main surface of the substrate next to the pixels or in the pixels.
  • the control circuit can also be arranged on an opposite rear surface of the substrate and can be electrically connected to the pixels by through- substrate-vias, TSVs . Further, the control circuit can be arranged in or on a further substrate.
  • the control circuit can comprise circuitry for driving and biasing the emitters.
  • the control circuit can comprise driving circuitry for the emitters and can be electrically connected to at least some of the emitters in the pixels.
  • the display device can comprise more than one control circuit. For example, each control circuit is assigned to a group of pixels, e.g. to a group of 16 x 16 pixels. The respective control circuit can drive the emitters and evaluate signals from sensors in said group of pixels.
  • control circuit is, based on the light sensed by the one or more sensors, configured to evaluate ambient light around the display.
  • the color composition of the ambient light can be analyzed.
  • control circuit is, based on the light sensed by the one or more sensors, configured to evaluate flicker noise. Therefore, based on a sensed flicker frequency, the refresh rate of the display can be adjusted.
  • control circuit is, based on the light sensed by the one or more sensors, configured to evaluate color of objects close to the display. For example, light is scattered by nearby objects and strikes the sensor ( s ) .
  • control circuit is, based on the light sensed by the one or more sensors, configured to adjust a white balance of the display.
  • White balance ensures that the display colors appear natural under di f ferent lighting conditions . It corrects the color temperature of light to ensure that white is perceived as a neutral hue .
  • the control circuit may be configured to analyze the sensed ambient light to determine the dominant color temperature . Based on the detected color temperature , the control circuit may be configured to adj ust the emitter color channels ( e . g . red, green, blue ) .
  • control circuit is , based on the light sensed by the one or more sensors , configured to adj ust a color calibration of the display .
  • Color calibration refers to the process of adj usting and aligning the colors produced by the display to ensure accurate and consistent color representation . This may be important because displays can vary in terms of color accuracy due to manufacturing di f ferences , aging, or other factors .
  • control circuit is , based on the light sensed by the one or more sensors , configured to dynamically adj ust color and brightness of emitted display light .
  • This can in particular mean that a closed loop process is enabled, in which the display light is continually adj usted based on the sensed ambient light and the feedback from the system itsel f .
  • the display device is allowed to sel f-regulate and maintain a desired state or performance .
  • a method of operating a display device is provided .
  • the method of operating can preferably be carried out with the display device described above . This means that all features disclosed for the display device are also disclosed for the method of operating the display device and vice versa .
  • the method of operating the display device is carried out with a display device comprising a plurality of emitters arranged in pixels on a main surface of a substrate , a sensor in at least one pixel , and filter on or above the sensor .
  • the method comprises filtering, by the filter, ambient light and transmitting light of a predetermined wavelength range to the sensor .
  • the filter can be formed as wavelength filter .
  • Ambient light refers to light that is not emitted by the emitters but that comes from other light sources outside the display device .
  • Ambient light may comprise light in a plurality of wavelength ranges .
  • the filter may filter the ambient light , such that only a portion of the originally wavelength spectrum is transmitted to the sensor .
  • the method further comprises sensing, by the sensor, light transmitted by the filter .
  • the sensed light can be filtered ambient light .
  • the emitters and the sensor are arranged such that display light , i . e . light emitted by the emitters , is not sensed by the sensor .
  • light barriers are arranged between the emitters and the sensor and/or the sensor is outside the field of illumination of the emitters and/or the sensor is disabled when the emitters are on .
  • the method of operating a display device comprises a plurality of emitters arranged in pixels on a main surface of a substrate , a sensor in at least one pixel , and a filter arranged on or above the sensor, comprises emitting light by the emitters , wherein each emitter comprises a light emitting diode , LED . It further comprises filtering, by the filter, ambient light and transmitting light of a predetermined wavelength range to the sensor . It further comprises sensing, by the sensor, light transmitted by the filter .
  • in-display sensing in particular spectral sensing is enabled .
  • the sensor can be embedded into the display .
  • the sensor can be used for wavelength dependent ambient light sensing, ALS .
  • a distributed ambient light sensor is formed .
  • Possible applications are auto white balance , AWB, for camera, AWB for display, spectral sensing and/or ambient light sensing, ALS .
  • the method further comprises adj usting a brightness of the emitted light by pulse width modulation .
  • Pulse width modulation, PWM, for LEDs is a technique used to control the brightness of an LED by varying the duty cycle of a pulsating electrical signal .
  • PWM Pulse width modulation
  • the LED is rapidly turned on and off at a fixed frequency, and the average intensity of light perceived by the human eye depends on the ratio of time the LED is on (the on-state) to the time it is off (the off-state) during each cycle.
  • PWM is an efficient and effective way to control LED brightness without changing the LED's forward current.
  • sensing light is performed when the emitters are in an off-state during the pulse width modulation.
  • sensing can be synchronized to the pulse width modulation of the LEDs.
  • light emitted by emitters is prevented from being sensed by the sensor. This allows to distinguish between ambient light and display light. For ambient light sensing, flicker detection, white balance etc. the surrounding light can be measured and disturbing crosstalk from the display light can be avoided.
  • sensing light is performed continuously during the pulse width modulation and the sensed light is evaluated by filtering a detection signal in frequency space.
  • the method further comprises , based on the sensed light , evaluating ambient light around the display .
  • the method further comprises , based on the sensed light , evaluating flicker noise .
  • the method further comprises , based on the sensed light , evaluating color of obj ects close to the display .
  • the method further comprises , based on the sensed light , adj usting a white balance of the display . In addition or alternatively, the method further comprises , based on the sensed light , adj usting a color calibration of the display . In addition or alternatively, the method further comprises , based on the sensed light , dynamically adj usting color and brightness of emitted display light .
  • a method of manufacturing a display device is provided . All features disclosed for the display device are also disclosed for the method of manufacturing the display device and vice-versa .
  • the method of manufacturing the display device further comprises mounting a plurality of emitters on a main surface of the substrate , wherein the emitters are arranged in pixels and each emitter comprises a light emitting diode , LED, configured to emit light during operation .
  • the emitters are formed by micro-LEDs and mounting the emitters on the substrate comprises a mass trans fer of said emitters from a carrier substrate to the substrate of the display device .
  • an elastomer stamp is used for the mass trans fer .
  • the method of manufacturing the display device further comprises forming a sensor in at least one pixel , the sensor being configured to sense light during operation .
  • Forming the sensor may comprise embedding a photodiode in the substrate .
  • the substrate is semiconductor substrate and the photodiode is formed in the substrate by a semiconductor manufacturing process , e . g . a CMOS process .
  • the photodiode is integrated in the substrate .
  • forming the sensor may comprise mounting a photodiode on the main surface of the substrate next to the emitters . This can mean that the photodiode forms a single detector chip that is trans ferred onto the substrate and attached to it .
  • the photodiode is a microphotodiode and trans ferred to the substrate in a similar way as the emitters , in particular by means of a further mass trans fer .
  • forming the sensor may comprise mounting an LED on the main surface of the substrate next to the emitters , and biasing said LED for sensing a photocurrent .
  • Said " sensor-LED” may have a similar or same structure as the "emitter-LEDs" .
  • the sensor and the emitters may be formed by a common manufacturing process and they may be trans ferred simultaneously to the substrate .
  • the sensor and the emitters may di f fer only in the way they are biased .
  • the sensor is a reverse biased or zero biased (micro- ) LED .
  • the method of manufacturing the display device further comprises forming a filter on or above the sensor, the filter being configured to transmit light of a predetermined wavelength range to the sensor .
  • the filter can be formed by depositing one or more filter layers on the sensor, or on a transparent cover that covers the emitters and the sensor .
  • the filter can be implemented as multi-layer interference filter or as color filter, by way of example .
  • the filter may be referred to as wavelength filter .
  • a display device with in-display spectral sensing can be manufactured .
  • a distributed ambient light sensor, ALS is formed that has multiple redundancies compared to a single ALS in a notch of a display . It also works when the sensor is partially covered .
  • an in-display sensor can manage and calibrate the display color appearance ( auto white balance ) locally and directly .
  • I f (micro- ) LEDs are used as sensors , fabrication can be facilitated, as both emitters and sensor can have the same structure and can be manufactured according to a common manufacturing process .
  • the method further comprises forming recesses on the main surface of the substrate , wherein in each recess a respective emitter or sensor is mounted .
  • recesses can comprise an etching process .
  • recesses are formed by a molding process or a thermocompression, for example .
  • the emitters and/or the sensor can be placed into the recesses by a pick-and-place process or, preferably, by a mass trans fer process , e . g . using an elastomer stamp .
  • a planari zed surface of the substrate can be provided .
  • Figures 1 to 3 show display devices according to embodiments of the present invention .
  • Figure 4 shows the external quantum ef ficiency of micro-LEDs i f biased for sensing a photocurrent .
  • Figures 5 to 7 show display devices according to other embodiments of the present invention .
  • Figure 8 show transmission characteristics of di f ferent filters .
  • Figure 9 show the transmission characteristics of Figure 8 folded with the external quantum ef ficiencies according to Figure 4 .
  • Figure 10 shows a display device according to another embodiment of the present invention .
  • Figure 11 shows a method of operating a display device according to an embodiment .
  • Figure 12 shows a method of manuf cturing a display device according to an embodiment .
  • Figure 1 shows a cross-sectional view of a display device 1 according to an embodiment .
  • the display device 1 comprises a substrate 10 with a main surface 12 .
  • a plurality of emitters 20 is arranged in pixels 2 on the main surface 12 of the substrate 10 , wherein each emitter 20 comprises a light emitting diode , LED, that is configured to emit light during operation .
  • a sensor 30 is integrated in at least one of the pixels 2 , the sensor 30 being configured to sense light during operation .
  • Figure 1 shows a crosssection of only one pixel 2 .
  • the display device further comprises a filter 70 arranged on or above the sensor 30 , the filter 70 being configured to transmit light of a predetermined wavelength range to the sensor 30 .
  • each emitter 20 is formed by a micro-LED .
  • the sensor 30 may be formed as a photodiode , wherein the photodiode is arranged on the main surface 12 of the substrate 10 next to the emitters 20 .
  • the sensor 30 is implemented as an LED, in particular micro-LED, that is arranged on the main surface 12 of the substrate 10 next to the emitters 20 and configured to be biased for sensing a photocurrent .
  • i f the sensor 30 is implemented as photodiode , it is also possible that the photodiode is embedded in the substrate 10 (not shown) .
  • the filter 70 can be implemented as interference filter or as color filter .
  • the display device 1 further comprises a transparent cover 60 .
  • the cover 60 is arranged in a vertical direction above the main surface 12 of the substrate 10 , such that the emitters 20 and the sensor 30 are covered .
  • the filter 70 is arranged on the cover 60 . As shown in Figure 1 , the filter can be arranged at a side of the cover 60 facing the sensor 30 .
  • FIG 2 another embodiment of the display device 1 is shown .
  • the embodiment of Figure 2 is di f ferent from the embodiment of Figure 1 in that the filter is arranged directly on the sensor 30 .
  • Figures 3a and 3b show di f ferent embodiments of a respective pixel 2 within the display device 1 in a top view .
  • the pixel 2 is formed as RGB-pixel 2 , in which a first emitter 20- 1 configured to emit red light , a second emitter 20-2 configured to emit green light , and a third emitter 30-3 configured to emit blue light are arranged .
  • the emitters 20 are formed as LEDs , in particular micro-LEDs .
  • the emitters 20 are arranged along a diagonal of the pixel 2 . However, di f ferent arrangements are also possible .
  • the pixels 2 of Figures 3a and 3b comprise a respective sensor 30 arranged along the diagonal of the emitters 20 .
  • the sensor 30- 1 of the pixel 2 according to Figure 3a can be formed by an LED, in particular micro-LED, that can emit blue or green light in forward bias mode .
  • said LED is configured to be biased for sensing a photocurrent . That is , said LED is configured to be reverse biased or zero biased .
  • blue or green micro-LEDs can generate a photocurrent in reverse bias with an external quantum ef ficiency of about 20% or more in a wavelength range between 350 nm and 500 nm .
  • the sensor 30-2 of the pixel 2 according to Figure 3b is formed by an LED, in particular micro-LED, that can emit red light in forward bias mode . However, said LED is configured to be biased for sensing a photocurrent .
  • said LED is configured to be reverse biased or zero biased . It has been found that red micro-LEDs can generate a photocurrent in reverse bias with an external quantum ef ficiency of about 20% or more in a wavelength range between 500 nm and 650 nm . Thus , by means of reverse biased or zero biased (micro- ) LEDs for red and blue/green light the visible wavelength range is covered .
  • FIG. 4 This is illustrated in Figure 4 showing the external quantum ef ficiency of micro-LEDs as function of the wavelength X .
  • the blue (B ) and green ( G) micro-LEDs cover a wavelength range from about 350 nm to 500 nm
  • red (R) micro-LEDs cover the wavelength range from about 450 nm to 650 nm
  • the display device 1 can use both red and blue/green micro-LEDs as sensors 30 to cover the full visible spectrum .
  • the display device 1 may comprise di f ferent groups of pixels 2 , wherein pixels 2 of a first group comprise a blue/green LED used as sensor 30 , and wherein pixels 2 of a second group comprise a red LED used as sensor 30 . It is also possible that blue/green LEDs and red LEDs used as sensors 30 are formed in the same pixel 2 . As both the emitters 20 and sensors 30 can be implemented as (micro- ) LEDs , they can be manufactured according to a common manufacturing process .
  • each pixel 2 or at least a subset of the plurality of pixels 2 comprises a respective sensor 30 .
  • the display device 1 can comprise a plurality of sensors 30 .
  • Each sensor 30 can be provided with a respective filter 70 configured to transmit light of a predetermined wavelength range to the sensor 30 .
  • the sensor area can be large and a distributed spectral sensor 30 can be formed .
  • a distributed spectral sensor has more redundancies than a local sensor and is less sensitive to disturbances . Integrating the sensor 30 into the display removes any notches from the display without the need to arrange the sensor behind the display like e . g . behind OLED sensing .
  • the display has not to be transparent .
  • FIGS 5 to 7 show further embodiments of the display device 1 , in which recesses 80 are formed on the main surface 12 of the substrate 10 .
  • a respective emitter 20 or sensor 30 is mounted in each recess 80 .
  • a metal coating 90 can be deposited on the sidewalls of the recess 80 and on the base of the recess 80 between the substrate 10 and the emitter 20 or the sensor 30 , respectively .
  • the metal coating 90 can act as bottom electrode for the emitter 20 or the sensor 30 and as reflector .
  • a transparent filler 92 can be arranged on lateral sides of the emitter 20/ sensor 30 to fill the remaining space of the recess 80 .
  • a transparent top electrode 94 is arranged on the main surface 12 of the substrate 10 , the transparent filler 92 and the emitter 20/ sensor 30 .
  • Figure 6 further shows the transparent cover 60 , on which a filter 70 is structured on a side facing the sensor 30 . As there is space between the filter 70 and the sensor 30 , light leakage from lateral sides is possible , as shown by an arrow .
  • Multi-layer interference filters 70 or metal filters 70 or color filters 70 can be micro-patterned using standard lithography procedures. For example, patterning of the filters 70 can be done after the sensor transfer onto the display plane and after top contacting.
  • the display device 1 comprises a plurality of sensors 30 and filters 70, different spectral channels are formed by the sensor-filter pairs. Each spectral channel is sensitive for a respective wavelength range. The spectral channels are distributed over the entire display with one or more channels in a pixel 2.
  • the control circuit 40 is electrically connected to the substrate 10 and the pixels 2 on the substrate 10 by means of electrical interconnections 45 .
  • the electrical interconnections 45 can be formed as flex connection 45 .
  • the control circuit 40 and the substrate 10 can be arranged on a common carrier 15 .
  • the control circuit can be arranged in or on the substrate 10 .
  • FIG 11 shows a possible operating method for the display device 1 .
  • the method comprises emitting light by the emitters 20 , wherein each emitter 20 comprises an LED .
  • the emitters 20 comprise a first emitter 20- 1 configured to emit red light , a second emitter 20-2 configured to emit green light and a third emitter 20-3 configured to emit blue light .
  • a brightness of the emitted light can be adj usted by pulse width modulation, PWM, as shown in Figure 11 .
  • the brightness can be adj usted separately for each of the emitters 20 , in particular the red LED 20- 1 , the green LED 20-2 and the blue LED 20-3 .
  • the on- states and of f-states of the LEDs may be synchroni zed, such that there is a common on-state phase and a common of f-state phase .
  • a PWM frequency f may be the same for all emitters 20 , as shown in Figure 11 .
  • To detect ambient light AL by means of the sensor 30 the detection is locked to time frames TA, in which the display is not on .
  • the sensor 30 may be disabled when the emitters 20 are on .
  • the on-states of the display are given by the pulse width modulation frequency and duty cycle .
  • Having a dedicated ambient light sensing window TA may refer to a PWM lock-in detection mode of the display device 1 .
  • ambient light sensing is performed continuously during the pulse width modulation and the sensed light is evaluated by filtering a detection signal in frequency space .
  • sensed ambient light can be distinguished from backscattered display light .
  • the ambient light is filtered by the filter 70 , such that only light of a predetermined wavelength range is transmitted to the sensor 30 .
  • FIG. 12 a manufacturing process of the display device is shown schematically .
  • the method comprises the following steps that are not necessarily carried out in this order but can be carried out in this order .
  • a substrate is provided in a first step S I .
  • the substrate is implemented as silicon backplane or as flexplane .
  • recesses 80 are formed on a main surface 12 of the substrate 10 .
  • the recesses are formed by etching the substrate 10 . It is also possible that the recesses are formed by molding, e . g . imprint molding, thermo-compression molding or inj ection molding .
  • a plurality of emitters 20 are mounted on the main surface 12 of the substrate 10 , wherein the emitters 20 are arranged in pixels 2 and each emitter 20 comprises a light emitting diode , LED, configured to emit light during operation .
  • Mounting the emitters 20 can comprise a trans fer process , in particular mass trans fer process , by which a plurality of emitters 20 are attached to the substrate 10 simultaneously .
  • an elastomer stamp is used for the mass trans fer .
  • a sensor 30 is formed in at least one pixel 2 , the sensor 30 being configured to sense light during operation .
  • Forming the sensor 30 may comprise embedding a photodiode in the substrate 10 , in particular i f the substrate 10 is a silicon substrate 10 . This can be done by a semiconductor process , e . g . a CMOS process . In this case , forming the sensor 30 can be performed before mounting the emitter 20 to the substrate 10 . Forming the sensor 30 may also comprise mounting a photodiode on the main surface 12 of the substrate 10 next to the emitters 20 .
  • the photodiode may be formed by a separate detector chip that is trans ferred and attached to the substrate 10 .
  • Forming the sensor 30 may also comprise mounting an LED, in particular micro-LED, on the main surface 12 of the substrate 10 next to the emitters 20 , and biasing said LED for sensing a photocurrent .
  • Said sensing (micro- ) LED can have the same structure as the emitter 20 . Thus , it can be formed in a same manufacturing process and it may be trans ferred to the substrate 10 in the same trans fer process as the emitters 20 . Biasing said LED for sensing a photocurrent can mean that this sensing LED is zero biased or reverse biased .
  • a filter 70 is formed on or above the sensor 30 , the filter 70 being configured to transmit light of a predetermined wavelength range to the sensor 30 .
  • Forming the filter 70 can comprise a depositing and structuring one or more filter layers directly on the sensor 30 or on a transparent cover 60 that covers the emitters 20 and the sensor 30 .

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Devices For Indicating Variable Information By Combining Individual Elements (AREA)

Abstract

L'invention concerne un dispositif d'affichage (1) qui comprend un substrat (10) comprenant une surface principale (12) et une pluralité d'émetteurs (20) agencés dans des pixels (2) sur la surface principale (12) du substrat (10), chaque émetteur (20) comprenant une diode électroluminescente, DEL, qui est conçue pour émettre de la lumière pendant le fonctionnement. Il comprend en outre un capteur (30) situé dans au moins un pixel (2), le capteur (30) étant conçu pour détecter la lumière pendant le fonctionnement. Il comprend en outre un filtre (70) disposé sur le capteur (30) ou au-dessus de celui-ci, le filtre (70) étant conçu pour transmettre au capteur (30) la lumière se trouvant dans une plage de longueurs d'onde prédéterminée. L'invention concerne également des procédés de fonctionnement et de fabrication d'un tel dispositif d'affichage (1). Les émetteurs et les capteurs peuvent être mis en œuvre sous la forme de micro-DEL.
PCT/EP2024/073320 2023-09-22 2024-08-20 Dispositif d'affichage pour détection de lumière ambiante et ses procédés de fonctionnement et de fabrication Pending WO2025061401A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102023125788 2023-09-22
DE102023125788.9 2023-09-22

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WO2025061401A1 true WO2025061401A1 (fr) 2025-03-27

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20200342194A1 (en) * 2016-05-23 2020-10-29 InSyte Systems Integrated light emitting display, ir light source, and sensors for detecting biologic characteristics
US20210327364A1 (en) * 2018-08-10 2021-10-21 Ams Ag Ambient light sensor system
EP3958309A1 (fr) * 2020-08-21 2022-02-23 ams International AG Affichage et procédé de fabrication d'un affichage
US20220254843A1 (en) * 2021-02-09 2022-08-11 Microsoft Technology Licensing, Llc Sensing ambient light from behind oled display
US20230132555A1 (en) * 2020-07-02 2023-05-04 Huawei Technologies Co., Ltd. Display apparatus and method of driving display apparatus

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20200342194A1 (en) * 2016-05-23 2020-10-29 InSyte Systems Integrated light emitting display, ir light source, and sensors for detecting biologic characteristics
US20210327364A1 (en) * 2018-08-10 2021-10-21 Ams Ag Ambient light sensor system
US20230132555A1 (en) * 2020-07-02 2023-05-04 Huawei Technologies Co., Ltd. Display apparatus and method of driving display apparatus
EP3958309A1 (fr) * 2020-08-21 2022-02-23 ams International AG Affichage et procédé de fabrication d'un affichage
US20220254843A1 (en) * 2021-02-09 2022-08-11 Microsoft Technology Licensing, Llc Sensing ambient light from behind oled display

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