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WO2025027160A1 - Système d'éclairage d'un dispositif d'affichage à pixels multiples - Google Patents

Système d'éclairage d'un dispositif d'affichage à pixels multiples Download PDF

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Publication number
WO2025027160A1
WO2025027160A1 PCT/EP2024/071888 EP2024071888W WO2025027160A1 WO 2025027160 A1 WO2025027160 A1 WO 2025027160A1 EP 2024071888 W EP2024071888 W EP 2024071888W WO 2025027160 A1 WO2025027160 A1 WO 2025027160A1
Authority
WO
WIPO (PCT)
Prior art keywords
coupling
display device
diffuser
light
speckle noise
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/EP2024/071888
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German (de)
English (en)
Inventor
Andre Hacke
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.)
Jenoptik AG
Carl Zeiss Jena GmbH
Original Assignee
VEB Carl Zeiss Jena GmbH
Carl Zeiss Jena 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 VEB Carl Zeiss Jena GmbH, Carl Zeiss Jena GmbH filed Critical VEB Carl Zeiss Jena GmbH
Publication of WO2025027160A1 publication Critical patent/WO2025027160A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/48—Laser speckle optics
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0013—Means for improving the coupling-in of light from the light source into the light guide
    • G02B6/0023—Means for improving the coupling-in of light from the light source into the light guide provided by one optical element, or plurality thereof, placed between the light guide and the light source, or around the light source
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/0035—Means for improving the coupling-out of light from the light guide provided on the surface of the light guide or in the bulk of it
    • G02B6/0036—2-D arrangement of prisms, protrusions, indentations or roughened surfaces
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices
    • G02F1/133602—Direct backlight
    • G02F1/133606—Direct backlight including a specially adapted diffusing, scattering or light controlling members
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices
    • G02F1/133602—Direct backlight
    • G02F1/133611—Direct backlight including means for improving the brightness uniformity
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/02—Diffusing elements; Afocal elements
    • G02B5/0273—Diffusing elements; Afocal elements characterized by the use
    • G02B5/0278—Diffusing elements; Afocal elements characterized by the use used in transmission

Definitions

  • aspects of the disclosure relate to a system for illuminating a multi-pixel display device, for example for a HUD system.
  • various aspects of the disclosure relate to a system for illuminating a multi-pixel display device with a speckle noise suppression unit.
  • Transparent screen units are used in various application scenarios.
  • transparent screen units are used in HUD systems (head-up display) in motor vehicles.
  • a HUD system creates a virtual image so that the driver does not have to take his eyes off the road and can still perceive the information displayed.
  • the virtual image is created in a virtual image plane.
  • the virtual image plane is located outside the vehicle.
  • the so-called eye box is the area within which the driver can perceive the virtual image.
  • Transparent display units have a picture generating unit (PGU).
  • the PGU comprises a multi-pixel display device, for example a liquid crystal display or a micromirror array.
  • the multi-pixel display device is illuminated by a light source.
  • HOE holographic optical elements
  • Laser light sources are therefore often used as light sources with a high luminous flux, which, due to their coherence, cause a considerable amount of speckle noise in the image plane.
  • speckle noise impairs the visual image impression.
  • Optical systems and arrangements used to illuminate multi-pixel display devices are described below. Speckle noise can be suppressed. The lighting intensity in a pixel level of the multi-pixel display device can be specifically adjusted. A compact design can be made possible. Such systems and arrangements can be used together with the multi-pixel display device as a PGU of a head-up display (HUD) system. In various variants, several diffuser elements arranged in a cascade are used. These are arranged in the beam path of the light in front of the multi-pixel display device and enable an adapted illumination of a pixel level of the multi-pixel display device.
  • HUD head-up display
  • the light is modified in stages by passing through several optical elements.
  • two or more diffusers can be passed through. This can ensure that the pixel plane of the multi-pixel display device is illuminated with a desired light distribution.
  • the multi-pixel display device has a radiation characteristic that is adjusted by illuminating the pixel plane by means of the plurality of optical elements.
  • a first diffuser can implement a speckle noise suppression unit.
  • the diffuser can be moved, e.g. in the kHz range.
  • a second diffuser can be set up to achieve suitable illumination of a third diffuser.
  • the third diffuser can have a radiation characteristic that is adapted to an optical imaging system that is arranged in the light path behind the multi-pixel display device. For example, a corresponding entrance pupil of the optical imaging system can be suitably illuminated.
  • Individual sections of the light beam path can be guided in an optical block or implemented as a free beam.
  • an optical block is used to guide the light.
  • a system for illuminating a pixel plane of a multi-pixel display device is disclosed.
  • the system comprises a laser light source.
  • the laser light source could comprise a single light emitter, for example a laser diode.
  • a multi-colour laser light source could also be used; such a multi-colour laser light source can comprise, for example, three light emitters providing light of the wavelengths red and green and blue.
  • the laser light source is generally designed to provide phase-coherent light, which can cause speckle noise.
  • the system also includes a speckle noise suppression unit.
  • speckle noise suppression unit As a general rule, different types of speckle noise suppression units can be used. One implementation involves the use of a moving diffuser, which "averages out" the speckle pattern. However, there are also other types of speckle noise suppression units, for example a liquid crystal light modulator element. By means of the speckle noise suppression unit, the phase profile of the laser light can be changed, in particular randomized.
  • an active arrangement can be used as a speckle noise suppression unit. suppression unit, i.e. an arrangement comprising a motor or actuator that moves one or more elements.
  • the speckle noise suppression unit can be designed, for example, as a diffuser that is moved in the kHz range.
  • the system also includes an optical waveguide that guides the coherent light emitted by the light source to the speckle noise suppression unit.
  • an optical fiber can be used as the optical waveguide.
  • a multimode fiber could be used.
  • An output lens could be provided at one end of the optical waveguide that faces the speckle noise suppression unit.
  • the system also includes an optical homogenization plate.
  • This has a top, a bottom and (at least) one side surface. The side surface is thus arranged at the edge between the top and the bottom.
  • the thickness of the optical homogenization plate can be defined as the distance between the top and the bottom.
  • the top can face a multi-pixel display device in a system integration in a PGU of a HUD system.
  • the homogenization plate can be made of plexiglass or glass.
  • the homogenization plate has a plate-shaped, optically transparent substrate.
  • the system comprises a coupling structure.
  • the coupling structure is formed on the side surface of the homogenization plate adjacent to a speckle noise suppression unit.
  • the coupling structure is designed to couple light coming from the speckle noise suppression unit into the homogenization plate.
  • the coupling structure can be glued or otherwise applied to the side surface of the homogenization plate as a separate component.
  • the coupling structure could also be formed as a surface topography variation of the side surface of the homogenization plate.
  • the system further comprises a coupling-out structure.
  • This is formed on the top of the homogenization plate.
  • the coupling-out structure is designed to couple light out of the homogenization plate over the entire surface of the coupling-out structure to illuminate the multi-pixel display device.
  • a certain light field i.e. a certain Intensity distribution as a function of the positions along the surface of the homogenization plate can be achieved.
  • This makes it possible to achieve suitable illumination of the pixel plane of the multi-pixel display device.
  • the pixel plane of the multi-pixel display device can be illuminated over its entire surface, ie all pixel elements are illuminated at one time or there is no sequential illumination of different pixel elements.
  • a particularly compact lighting unit can be implemented, e.g. especially in comparison to a free-beam beam path.
  • the coupling-out structure can be implemented in particular as a diffuser.
  • the light is scattered by means of a diffuser so that a specific radiation characteristic is achieved.
  • the diffusers can be implemented in different ways, e.g. as a microstructured diffuser, holographic diffuser, volumetric diffuser and surface relief based diffuser.
  • the diffusers can be made of different materials, including plastic, glass and possibly with a coating.
  • a system for illuminating a pixel plane of a multi-pixel display device comprises a laser light source.
  • the laser light source is configured to emit light along a beam path.
  • the system also comprises a speckle noise suppression unit, which is implemented, for example, as a moving diffuser. This is arranged in the beam path.
  • the system further comprises a diffuser. The diffuser is arranged in the beam path starting from the laser light source behind the speckle noise suppression unit and is configured to emit the light with a radiation characteristic in the direction of the multi-pixel display device.
  • the diffuser arranged first in the beam path enables the suppression of speckle noise.
  • the diffuser arranged in the beam path adjacent to the pixel plane of the multi-pixel display device enables a desired Radiation characteristics for, firstly, the illumination of the pixel plane and, secondly, the illumination of an entrance pupil of an optical imaging system which is arranged in the beam path behind the multi-pixel display device.
  • the diffuser which is arranged between the speckle noise suppression unit and the diffuser (near the display device) and which is set up to emit the light with a further radiation characteristic in the direction of the diffuser arranged adjacent to the display device.
  • This further radiation characteristic can be set up to achieve the full-surface illumination of the aperture of the diffuser arranged adjacent to the display device.
  • Such systems as described above can be part of a PGU of a HUD system.
  • the HUD system can have one or more HOEs in the beam path of the light.
  • the multi-pixel display device can be, for example, a liquid crystal display or a micromirror array.
  • the one or more HOEs can perform different functions.
  • the one or more HOEs are part of a wavefront manipulator or implement it, as described in WO 2022/189275 A1 (referred to therein as holographic elements), the corresponding disclosure content being incorporated herein by cross-reference.
  • a corresponding wavefront manipulator can comprise two HOEs that are arranged directly one behind the other in the beam path.
  • the two HOEs are also designed to be reflective for at least one specified wavelength and a specified angle of incidence range. Light waves of the at least one specified wavelength and the specified angle of incidence range are thus efficiently diffracted.
  • the holographic elements are preferably also designed to be transmissive, in other words transmissive for wavelengths that do not correspond to the at least one specified wavelength and have an angle of incidence outside the specified angle of incidence range.
  • One advantage is, for example, that, particularly in connection with a head-up Display, the image quality can be significantly improved by the individual design of the HOEs.
  • the HOE requires almost no installation space, so that a corresponding wavefront manipulator can be used to achieve a significant increase in image quality in only a small amount of available installation space, such as in a head-up display designed for a motor vehicle (compared to implementations without HOE).
  • the holographic arrangement in particular achieves a high refractive power, comparable to the refractive power achieved, for example, by a transmissive optical component without chromatic aberration.
  • reflective HOEs offer a wider angle spectrum with high efficiency and higher wavelength selectivity for a defined wavelength.
  • the holographic arrangement enables a large field of view with high efficiency at the same time and is therefore suitable for both VR head-up displays (VR - virtual reality) and augmented reality head-up displays (AR-HUD) with a large field of view and large numerical aperture.
  • VR- virtual reality VR - virtual reality
  • AR-HUD augmented reality head-up displays
  • Other possible applications include head-up displays with curved projection surfaces, for example head-up displays for windshields of vehicles, in particular motor vehicles, aircraft or ships, and generally for viewing windows. While various variants are described below in which one or more HOEs are used in the optical imaging system of a HUD system, the corresponding techniques for an image generation unit can also be used in connection with non-holographic HUD systems.
  • FIG. 1 is a schematic view of an exemplary system for illuminating a multi-pixel display device.
  • FIG. 2 is another side view of the exemplary system of FIG. 1 .
  • FIG. 3 is a perspective view of the exemplary system of FIG. 1.
  • FIG. 4 shows the illumination intensity provided by the system along a pixel plane of the multi-pixel display device.
  • FIG. 5 illustrates a HUD system with the multi-pixel display illumination system and the pixel display according to various examples.
  • FIG. 6 is a polar plot (nominated) showing two possible angular distributions of the radiation pattern of the system for illuminating the multi-pixel display device.
  • FIG. 7 illustrates a local variation of the radiation characteristics by several polar plots of the corresponding angular distributions according to different examples.
  • FIG. 8 illustrates a local variation of the radiation characteristics by several polar plots of the corresponding angular distributions according to different examples.
  • FIG.9 schematically illustrates a speckle noise suppression unit according to various examples.
  • FIG. 10 schematically illustrates a HUD system according to various examples.
  • FIG. 11 is a schematic view of an exemplary system for illuminating a multi-pixel display device.
  • FIG. 12 is a perspective view of a structural implementation of the system of FIG. 11.
  • FIG. 1 schematically illustrates a system 100 for illuminating a multi-pixel display device 10.
  • Laser light e.g. red-green-blue channels or fewer or more channels
  • a speckle noise suppression unit 3 - here implemented as a dynamically moving diffuser - by means of an optical waveguide 4.
  • a lens can optionally be provided at the corresponding end of the optical waveguide 4, e.g. a GRIN lens. The radiation characteristics of such a lens can be varied depending on the application.
  • the lens can provide collimation.
  • a lens with a collimation characteristic can be provided that is adapted to an input angle range of the speckle noise suppression unit 3. In this case, particular attention should be paid to the dispersion.
  • a parabolic mirror can be used for beam expansion and collimation between the end of the optical fiber 4 and the speckle noise suppression unit 3.
  • the multi-pixel display device 10 together with the system 100 can be part of a PGU of a HUD system. It would also be conceivable for the multi-pixel display device 10 together with the system 100 to be part of a holo-diffuser. With such a holo-diffuser, an image is generated in an image plane that is arranged on a transparent surface. Transparent screens can be implemented in this way, for example.
  • one or more HOEs may be present in particular, which apply one or more optical effects to the light by means of diffraction.
  • the light can be redirected or collimated.
  • the one or more HOEs require that the light source emits narrowband or monochromatic light.
  • a laser is typically used as the light source for this.
  • the coherent light can be susceptible to speckle noise.
  • Speckle noise also light granulation or laser granulation or speckle for short refers to the grainy interference phenomena that can be observed with sufficiently coherent illumination of optically rough object surfaces (unevenness in the order of the wavelength).
  • the diffuser implementing the speckle noise suppression unit 3 is randomly moved in both lateral directions perpendicular to the axis of the optical waveguide 4 and in relation to the rest of the structure.
  • the movement frequency can be adjustable. This allows speckle noise to be effectively suppressed.
  • the light is then coupled into the transparent substrate of an optical homogenization plate 1 (e.g. made of glass or plastic) in a coupling structure 2 (can also be referred to as a light redistribution structure).
  • the coupling structure 2 is arranged on a side surface 23 of the homogenization plate 1 directly adjacent to the speckle noise suppression unit 3. This enables a compact structure; additional collimation lenses or the like are unnecessary.
  • a typical thickness of the homogenization plate 1 is in the range of 5 mm to 20 mm, preferably in the range of 10 mm to 20 mm.
  • the coupling structure 2 can be applied as a separate component to the homogenization plate 1.
  • the coupling structure 2 can be designed, for example, as a lenticular array.
  • a lenticular array generally comprises a 1-D or 2-D array of lens-shaped elements (lenticules) arranged to refract light in different directions.
  • a 1-D array may be used in which the lenticules are spaced apart in a first direction and the lenticules are extended in a second direction perpendicular thereto.
  • the coupling structure 2 can be designed as a film, for example a lenticular array film. However, it would also be possible for the coupling structure 2 to be designed integrally with the homogenization plate 1, i.e. as a monolithic component.
  • the side surface 23 can be designed with a corresponding surface topography (e.g. as a lenticular array in the form of indentations on the side surface 23).
  • the light-conducting substrate of the optical homogenization plate 1 is provided on its underside 22 with a further transparent light redistribution structure 5, which redistributes the light field according to the desired design specifications, e.g. by multiple scattering and reflection 9.
  • the light redistribution structure 5 can be applied as a separate component to the homogenization plate 1.
  • the light redistribution structure 5 is, for example, in the form of (semi-)spherical or ellipsoidal elevations or depressions directly in the substrate, but can also be done by gluing on a structural film that is adapted to the refractive index.
  • the light redistribution structure 5 can, for example, alternatively be designed as a film, for example a lenticular array film.
  • the light redistribution structure 5 can be designed integrally with the homogenization plate 1, ie as a monolithic component.
  • the underside 22 can be designed with a corresponding surface topography (eg as a lenticular array in the form of indentations).
  • the design specifications such as lateral homogeneity and spatial orientation of the light field 8 emitted by the homogenization plate 1 (radiation characteristics of the homogenization plate 1) can be set by the configuration, arrangement, size and/or number of such light redistribution structures (the main radiation direction 205 - perpendicular to the surface of the homogenization plate 1 - is also provided with a reference symbol). Details in connection with the light intensity of the light field 8 as a function of the position on the homogenization plate and the radiation characteristics of the light field 8 are described later in connection with FIG. 4 and FIG. 6.
  • a reflector structure 6 is provided, here designed as a reflective layer.
  • the reflector structure 6 directs the light back in the direction of the optical homogenization plate 1.
  • the reflector structure 6 can, for example, be glued to the light redistribution structure 5 as a reflective film. It would also be possible for the reflector structure 6 to be produced as a metallic vapor deposition (thin layer), for example with aluminum.
  • an output coupling structure 7 can optionally be used on the upper side 21 of the homogenization plate 1.
  • This can be designed as a diffractive diffuser.
  • several diffuser elements arranged in a cascade are used, namely the diffractive diffuser implementing the output coupling structure 7 and the diffuser implementing the speckle noise suppression unit 3.
  • a pixel level 11 of the multi-pixel display device 10 can be illuminated in a tailor-made manner. Pixels of a liquid crystal display, for example a thin-film liquid crystal display (TFT display), are arranged in the pixel level 11.
  • TFT display thin-film liquid crystal display
  • the coupling-out structure 7 can be applied to the homogenization plate 1 as a separate component.
  • the coupling-out structure 7 can be designed as a film, for example.
  • the upper side 21 can be designed with a corresponding surface topography.
  • the optical homogenization plate 1 in various examples it would be possible for the optical homogenization plate 1 to be manufactured together with the outcoupling structure 7, the incoupling structure 2 and the light redistribution structure 5 as a monolithic component.
  • this monolithic component could be made from a plastic block. Possible manufacturing techniques include 3D printing or injection molding.
  • the gap 12 preferably has an extension in the range of approximately 20 mm to 100 mm, optionally in the range of 25 mm to 25 mm, further optionally of 30 mm.
  • the gap 12 is therefore typically larger than the thickness of the homogenization plate 1.
  • the gap 1 has, for example, an extension of approximately 100% to 150% of a thickness of the homogenization plate 1, because the homogenization plate 1 is typically between 5 mm and 20 mm thick.
  • the dimensioning of the gap 12 does not depend on the thickness of the homogenization plate 1, but rather on the positioning of the virtual image plane: This is explained below.
  • the human eye adapts - for example in a HUD system - to the virtual image plane.
  • This virtual image plane is mapped to pixel level 11.
  • structures - such as the diffuser features of the Output coupling structure - which are spaced from the pixel plane 11 by a distance greater than a depth of field, are only imaged very blurred and are therefore not perceived (or at least not perceived as disturbing).
  • This is particularly advantageous for magnifying optical systems, such as the HUD system.
  • the pixel plane 11 is magnified and imaged onto the virtual image plane. Magnification factors of 10x or more, e.g. 15x or more, are conceivable.
  • the virtual image plane can be located virtually at infinity (the eye's long-distance accommodation is > 5 m) and have a large extent in the eye's field of vision.
  • distances between the eyebox and the virtual image plane of more than 5 m or more than 10 m or more than 20 m are conceivable. If in such a case the gap 12 were to be particularly small, so that the diffuser features of the coupling-out structure 7 were within the depth of field, they would be particularly large and thus perceived as particularly disturbing in the viewer's field of vision.
  • FIG. 2 is a side view of the system 100 from FIG. 1.
  • the lateral extent of the coupling structure 2 is smaller than the extent of the side surface 23 of the homogenization plate 1, i.e. along the z-axis in FIG. 2 along the long side of the side surface 23.
  • the coupling structure 2 covers approximately 70% of the side surface 23.
  • the lateral extent of the coupling structure 2 is not greater than 80% or not greater than 70% percent of a side length of the side surface 23 or not greater than 50% percent of a side length of the side surface 23.
  • the coupling structure 2 covers the entire side 23.
  • the lateral extent of the coupling structure 2 can be equal to the side length of the side surface 23.
  • the aperture of the speckle noise suppression unit 3 is also smaller than the lateral extent of the coupling structure 2.
  • the lateral extent of the speckle noise suppression unit 3 cannot be larger than 20% of the area of the coupling structure 2.
  • the coupling structure 2 can be used to couple the light into the homogenization plate 1 over a relatively large area, although the speckle noise suppression unit 3 typically has a relatively limited extent in relation to the side surface 23.
  • the extent (width over the side surface) and texture (lens-shaped, prismatic) of the coupling structure 2 can be variably adapted (design degrees of freedom).
  • the coupling structure 2 can comprise one or more prismatic structures; these serve as scattering geometries for light that has already been coupled in and internally reflected/scattered.
  • the radiation characteristics of the homogenization plate 1 - ie the light distribution, e.g. homogeneity, of the coupling-out structure 7 - can thus be influenced at the location of the coupling structure 2.
  • the light is also further redistributed within the homogenization plate 1, for example by the light redistribution structure 5. For this reason, it is not absolutely necessary for the lateral extension of the coupling structure 2 to cover the entire length of the side surface 23. This is also evident in the perspective view of the system 100 in FIG. 3.
  • FIG. 4 shows the light intensity in the pixel plane 11 (the extent of the pixel plane 11 is indicated in FIG. 4 by the double arrow).
  • the light intensity is determined by the emitted light field 8 (e.g. as an integral over all solid angles, as in FIG. 4, or also only for the main emission direction 205).
  • a constant light intensity over the extent of the pixel area 11 can be achieved by appropriately shaping the light field 8 (for example by appropriately configuring the coupling-out structure 7 and/or the light redistribution structure 5 and/or the coupling-in structure 2).
  • other local dependencies of the light intensity would also be conceivable, for example with a peak in the center of the pixel plane 11 or with several different maxima and minima of the light intensity.
  • FIG. 5 schematically illustrates a HUD system 200.
  • the HUD system 200 comprises the system 100 (only the homogenization plate 1 is shown in FIG. 5) for illuminating the multi-pixel display device 10.
  • the pixel plane 11 is inclined relative to the homogenization plate 1.
  • the main radiation direction 205 of the system 100 is shown.
  • FIG. 5 shows further components of the HUD system 200 along the beam path of the light, for example, a mirror 206, a holographic optical element 202, the windshield 203 and the eyebox 204.
  • the radiation characteristics of the homogenization plate 1 are also crucial for the quality of the image displayed by the HUD system 200.
  • the radiation characteristics can be adjusted in particular by using a holographic diffuser as the coupling-out structure 7.
  • a holographic diffuser as the coupling-out structure 7.
  • two exemplary radiation characteristics 291, 292 each normalized in amplitude to a common value for the main radiation direction 205, whereby in the example shown the main radiation direction is perpendicular to the surface of the coupling-out structure 7, i.e.
  • the polar plot shows the amplitude of the light emitted in the respective direction (in the x-y plane).
  • This amplitude distribution in the angular space specifies the radiation characteristics.
  • the width of an angular spectrum of the light field 8 can be set using the coupling-out structure 7: the respective width 295, 296 is shown in FIG. 6. It is particularly clear from FIG. 6 that the radiation characteristics have an angular spectrum that does not completely illuminate the half-space above the coupling-out structure 7, i.e.
  • the light is emitted in a more directed manner compared to a -90° -+90° reference radiation characteristic 299 (dotted line), which evenly illuminates the entire upper half-space.
  • This allows the multi-pixel display device 10 to be illuminated in a targeted manner.
  • the radiation characteristics in the angular spectrum to be as shown in FIG. 6, as a function of the lateral position (for example along the X-axis plotted in FIG. 4) by changing the diffractive properties of the holographic diffuser as a function of this position.
  • the appropriate radiation characteristics 291, 292 angular spectrum and/or lateral variation
  • FIG. 6 is only an example of a radiation characteristic. Inhomogeneous radiation characteristics are also conceivable.
  • the lighting system and the imaging system (HUD) should be adapted to each other. This means that the exit pupil of the lighting system and the entrance pupil of the HUD are adjusted to each other in order to This is to achieve the greatest possible luminous flux and to avoid vignetting of the lighting system. This can also result in inhomogeneous or asymmetrical beam characteristics.
  • FIG. 7 and FIG. 8 show variants in which the radiation characteristics are changed by varying the respective angle spectrum 801 -805 or 811 -815 as a function of the lateral position along the x-axis (alternatively or additionally along the z-axis).
  • the width of the angle spectrum is kept approximately the same, but the orientation of the main radiation direction 205 is tilted once progressively away from the center 7' of the coupling-out structure 7 (FIG. 7) and once progressively towards the center 7' of the coupling-out structure 7 (FIG. 8).
  • This means that the main radiation direction 205 is changed by rotating the angle spectrum 801 - 805, 811-815 for different x-positions.
  • the "radiation lobe" of the light is tilted progressively, but retains approximately the same shape. In the illustrated examples, this is done symmetrically with respect to a center 7' of the coupling-out structure 7, but in other examples it could also be done asymmetrically with respect to the center 7'.
  • the entrance pupil of the optical imaging system of the HUD system or the eyebox 204 can be illuminated in order to achieve a natural and uniform brightness impression.
  • FIG.9 shows a schematic of a speckle noise suppression unit 300.
  • the speckle noise suppression unit 300 comprises a diffuser 301 in an xy plane.
  • Different types of drive are conceivable for moving the diffuser 301 in the xy plane.
  • an electrodynamic drive can be used.
  • An electrodynamic drive also referred to as an electromagnetic drive, uses, for example, a coil to generate an alternating magnetic field by moving a magnet. The magnet is connected to the diffuser 301.
  • Corresponding actuators 303 which are mounted via a frame in a fixed reference system (mounting 304), are shown in FIG. 9.
  • the drive frequency of the electrodynamic actuators 303 can be dynamically adjusted in a relatively wide frequency range, so that, for example, one or more eigenmodes of the mass-spring system (formed by the diffuser 301 and return springs 302) are resonantly excited. In such resonant states, the best despeckle Results can be achieved.
  • This type of drive can be designed as a one- or two-axis system (a two-axis system is shown as an example in FIG.9).
  • vibration motors eg miniature motor with eccentric flywheel on motor shaft
  • the movement frequency should not be less than 100 Hz.
  • the optimal frequency range depends on the geometry and mass of the diffuser (natural frequency of the mass-spring system).
  • Psychoacoustic effects should also be taken into account during the design, so there may be a trade-off between different target values.
  • the scenario in FIG.9 is just one example of a hardware implementation of a speckle noise suppression unit.
  • the beam path of the light can be changed over time. This can be achieved by mechanical movement (such as vibration or rotation) of an element in the beam path, such as a diffuse disk (see FIG.9) or a fiber optic.
  • the temporal change of the beam path leads to the speckles being "smeared” over time, which reduces the perceived noise.
  • the phase of the incident light could also be changed, e.g. by means of spatial light modulators (SLMs).
  • SLMs spatial light modulators
  • FIG. 10 schematically illustrates a HUD system 600 according to various examples.
  • the HUD system 600 includes a PGU 601.
  • the PGU 601 includes a laser light source 605 configured to emit light along a beam path 606.
  • the laser light source 605 corresponds to the laser light source 19 of FIG. 1.
  • the light strikes a speckle noise suppression unit 610.
  • the speckle noise suppression unit 610 can be configured, for example, as described in FIG. 9 (speckle noise suppression unit 300).
  • the light propagates along the beam path 606 to an optical element 615.
  • the optical element 615 is designed to evenly illuminate the aperture of a diffuser 620.
  • An example of the optical element 615 would be, for example, the Homogenization plate 1 together with the light redistribution structure 5 (see FIG. 1 ). It is possible that the optical element 615 itself is designed as a diffuser. A corresponding implementation will be discussed later in connection with FIG. 11.
  • the diffuser 620 (see FIG. 1: coupling-out structure 7) is then set up to emit the light along the beam path 606 with an emission characteristic that illuminates the pixel plane of a multi-pixel display device 625 (corresponds to the multi-pixel display device 10 from FIG. 1).
  • the units 605, 610, 615, 620 thus form a system 621 that corresponds, for example, to the system 100 from FIG. 1.
  • the light then leaves the PGU 601 along the beam path 606 and strikes an optical imaging system 630, which has, for example, one or more holographic optical elements.
  • the optical imaging system 630 can alternatively or additionally have, for example, one or more deflection elements or lenses.
  • the emission characteristics of the diffuser 620 are set up so that the light illuminates the entrance pupil of the optical imaging system 630.
  • the light then reaches an eyebox 645, from where a virtual image can be perceived. Corresponding techniques were described above in connection with FIGS. 6, 7 and 8.
  • the section of the beam path 606 between the laser light source 605 and the speckle noise suppression unit 610 can be implemented at least partially via an optical waveguide, for example a glass fiber.
  • an optical waveguide for example a glass fiber.
  • FIG. 11 schematically illustrates a system 500.
  • the system 500 provides functionality that corresponds to the system 100 of FIG. 1.
  • the system 500 can, for example, implement the system 621 of FIG. 10.
  • a free beam path is used for the light to illuminate a multi-pixel plane 506 of a multi-pixel display device 507.
  • the light is generated by a laser light source 501 (cf. laser light source 19 in FIG. 1 and laser light source 605 in FIG. 10).
  • the light propagates from the laser light source 501 to a speckle noise suppression unit 502. This can be designed like the speckle noise suppression unit 3 in FIG. 1 or the speckle noise suppression unit 300 in FIG. 9.
  • the light can propagate as a free beam between the laser light source 501 and the speckle noise suppression of a 502. It would also be conceivable that the light is guided by a glass fiber.
  • the speckle noise suppression unit 502 itself has a moving diffuser that implements a specific radiation characteristic 507. This illuminates another diffuser 504, which in turn has a radiation characteristic
  • the radiation characteristic 508 is set up to achieve a homogeneous illumination of a further diffuser 505.
  • the diffuser 504 thus takes over the functionality of the homogenization plate 1 together with the light redistribution structure 5 in FIG. 1.
  • the light can propagate as a free beam between the speckle noise suppression unit and the diffuser 504 and between the diffuser 504 and the diffuser 505.
  • the diffuser 505 has a radiation characteristic 509. This radiation characteristic 509 can be adjusted to illuminate an entrance pupil of an optical imaging system of a HUD system as desired.
  • the radiation characteristic 509 can be adjusted to illuminate an entrance pupil of an optical imaging system of a HUD system as desired.
  • FIG. 509 can be set according to the examples in FIG. 6, FIG. 7 and FIG. 8.
  • the pixel level 506 of the multi-pixel detector 507 is illuminated. This in turn has a radiation characteristic 510.
  • Corresponding aspects have already been discussed in connection with FIG. 1 and the pixel level 11 of the multi-pixel detector
  • One or more narrow-band and coherent light sources can be used for the efficient illumination of the multi-pixel display device.
  • a PGU of a HUD system can be implemented in this way.
  • Techniques are described for how speckle noise can be suppressed.
  • Techniques are described for how a homogeneous illumination of large image fields is possible.
  • One or more diffusers are used for this.
  • the light distribution or the light field can be flexibly adjusted by the appropriate configuration of coupling-out structures (e.g. implemented as a diffuser) or coupling-in structures (e.g. implemented as a diffuser) or light redistribution structures. High luminances can be achieved.
  • the corresponding system for illuminating the multi-pixel display device can be arranged at a distance from a pixel plane of the multi-pixel display device (for example, translationally/parallel shifted and/or inclined).
  • the light source can be arranged on the optical elements for light redistribution, which allows flexibility in terms of the required installation space and reduces unwanted heat input.
  • a compact design of the system for illuminating the multi-pixel display device can be achieved, for example a small thickness perpendicular to the pixel plane of the multi-pixel display device.
  • FIG. 12 is a perspective view of a concrete implementation of the system 500 from FIG. 11. Two deflection mirrors 521, 522 are also shown.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
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  • Mathematical Physics (AREA)
  • Chemical & Material Sciences (AREA)
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Abstract

L'invention concerne une plaque d'homogénéisation optique (1) qui est utilisée pour éclairer un dispositif d'affichage à pixels multiples (10), par exemple un écran à cristaux liquides. Une unité de suppression de bruit de chatoiement (3, 300) est prévue pour réduire le bruit de chatoiement avant que la lumière ne soit couplée dans la plaque d'homogénéisation (1). Des composants de ce type peuvent être utilisés dans un dispositif de génération d'image d'un système HUD.
PCT/EP2024/071888 2023-08-02 2024-08-01 Système d'éclairage d'un dispositif d'affichage à pixels multiples Pending WO2025027160A1 (fr)

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DE102023120547.1A DE102023120547A1 (de) 2023-08-02 2023-08-02 System zur beleuchtung eines mehrpixel-anzeigegeräts
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US20030128538A1 (en) * 2000-02-28 2003-07-10 Masayuki Shinohara Surface light source, method for manufacturing the same and apparatus using it
CA2739262A1 (fr) * 2008-09-02 2010-03-11 Elbit Systems Of America, Llc Systeme et procede de dechatoiement d'une image eclairee par une source de lumiere coherente
US20100103347A1 (en) * 2005-08-04 2010-04-29 Kiminori Mizuuchi Display and illuminator
US20160327906A1 (en) * 2014-01-07 2016-11-10 Seereal Technologies S.A. Display device for holographic reconstruction
WO2022189275A1 (fr) 2021-03-10 2022-09-15 Carl Zeiss Jena Gmbh Manipulateur de front d'onde pour un affichage tête haute, ledit manipulateur de front d'onde comprenant un élément holographique, ensemble optique et affichage tête haute
US20230176377A1 (en) * 2021-12-06 2023-06-08 Facebook Technologies, Llc Directional illuminator and display apparatus with switchable diffuser

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US5313479A (en) * 1992-07-29 1994-05-17 Texas Instruments Incorporated Speckle-free display system using coherent light
WO2006059264A1 (fr) * 2004-11-30 2006-06-08 Koninklijke Philips Electronics N.V. Systeme d'eclairage utilisant une source laser pour un dispositif d'affichage
DE102021130561A1 (de) * 2021-11-23 2023-05-25 Carl Zeiss Jena Gmbh Projektor oder display mit scannender lichtquelle und pixeliertem array

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030128538A1 (en) * 2000-02-28 2003-07-10 Masayuki Shinohara Surface light source, method for manufacturing the same and apparatus using it
US20100103347A1 (en) * 2005-08-04 2010-04-29 Kiminori Mizuuchi Display and illuminator
CA2739262A1 (fr) * 2008-09-02 2010-03-11 Elbit Systems Of America, Llc Systeme et procede de dechatoiement d'une image eclairee par une source de lumiere coherente
US20160327906A1 (en) * 2014-01-07 2016-11-10 Seereal Technologies S.A. Display device for holographic reconstruction
WO2022189275A1 (fr) 2021-03-10 2022-09-15 Carl Zeiss Jena Gmbh Manipulateur de front d'onde pour un affichage tête haute, ledit manipulateur de front d'onde comprenant un élément holographique, ensemble optique et affichage tête haute
US20230176377A1 (en) * 2021-12-06 2023-06-08 Facebook Technologies, Llc Directional illuminator and display apparatus with switchable diffuser

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