WO2020215184A1 - 显示装置 - Google Patents

显示装置 Download PDF

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Publication number
WO2020215184A1
WO2020215184A1 PCT/CN2019/083717 CN2019083717W WO2020215184A1 WO 2020215184 A1 WO2020215184 A1 WO 2020215184A1 CN 2019083717 W CN2019083717 W CN 2019083717W WO 2020215184 A1 WO2020215184 A1 WO 2020215184A1
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WO
WIPO (PCT)
Prior art keywords
grating
lens unit
compound lens
unit
display
Prior art date
Application number
PCT/CN2019/083717
Other languages
English (en)
French (fr)
Inventor
王维
陈小川
刘佳尧
凌秋雨
孟宪芹
孟宪东
梁蓬霞
王方舟
刘佩琳
Original Assignee
京东方科技集团股份有限公司
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 京东方科技集团股份有限公司 filed Critical 京东方科技集团股份有限公司
Priority to PCT/CN2019/083717 priority Critical patent/WO2020215184A1/zh
Priority to US16/765,583 priority patent/US11640020B2/en
Priority to CN201980000529.4A priority patent/CN112119342B/zh
Publication of WO2020215184A1 publication Critical patent/WO2020215184A1/zh

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/18—Diffraction gratings
    • G02B5/1842—Gratings for image generation
    • 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
    • G02B27/42—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect
    • G02B27/4205—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect having a diffractive optical element [DOE] contributing to image formation, e.g. whereby modulation transfer function MTF or optical aberrations are relevant
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/18—Diffraction gratings
    • G02B5/1814—Diffraction gratings structurally combined with one or more further optical elements, e.g. lenses, mirrors, prisms or other diffraction gratings

Definitions

  • the embodiment of the present disclosure relates to a display device.
  • At least one embodiment of the present disclosure provides a display device, the display device includes a display layer and a lens layer, the lens layer is disposed on the light exit side of the display layer, and includes at least one grating compound lens unit; the display The layer includes at least one display pixel set, and the display pixel set is configured to emit light for imaging toward the grating compound lens unit during the display process; the grating compound lens unit is configured to perform optical processing on the display pixel set. Imaging; and the grating compound lens unit is further configured to deflect the light used for imaging so that the image center field direction of the grating compound lens unit crosses the extension direction of the optical axis of the grating compound lens unit , So that the display device has one or more viewpoints.
  • the grating compound lens unit includes a lens unit and a grating unit; the lens unit is configured to optically image the display pixel set; and the grating unit is configured to pass The light used for imaging is deflected so that the image-side center field of view direction of the grating compound lens unit crosses the extension direction of the optical axis of the lens unit.
  • the lens layer further includes a central lens arranged in parallel with the grating compound lens unit; the display layer further includes a central display pixel arranged in parallel with the display pixel set
  • the central display pixel set is configured to emit light for imaging toward the central lens during the display process; the central lens is configured such that the light for imaging emitted by the central display pixel set forms the center The imaging point of the display pixel set; and the grating unit is configured to make the image of the display pixel set cross the image center field direction of the grating compound lens unit and the extension direction of the optical axis of the lens unit
  • the point and the imaging point of the central display pixel set are joined together to form at least a part of the image to be displayed of the display device.
  • the lens unit and the grating unit are attached to and overlapping each other; and the lens unit is closer to the display layer than the grating unit.
  • the lens unit and the grating unit are integrally formed as a phase lens; and the phase lens is configured to image the display pixel set while simultaneously The image center field direction of the grating compound lens unit deviates from the optical axis of the lens unit.
  • the phase of the lens unit is symmetrically distributed with respect to the center of the grating compound lens unit; and the phase of the grating compound lens unit is relative to the grating compound lens unit.
  • the centers are asymmetrically distributed.
  • the grating unit includes a plurality of grating lines, and orientation directions of the plurality of grating lines are parallel to each other.
  • the grating unit includes a plurality of grating sub-regions; and the plurality of grating sub-regions are configured to direct light incident to different grating sub-regions in different directions The deflection is used to make the display device have multiple viewpoints.
  • the arrangement of the plurality of viewpoints is a row arrangement, a cross arrangement, a matrix arrangement, or a rice-shaped arrangement.
  • the grating compound lens unit includes a first grating compound lens subarea and a second grating compound lens subarea; the image center view of the first grating compound lens subarea is The angle between the field direction and the optical axis of the lens unit of the first grating compound lens sub-region is a first angle, and the image center field direction of the second grating compound lens sub-region is relative to the second grating compound lens sub-region.
  • the included angle of the optical axis of the lens unit of the zone is a second angle; the first angle is not equal to the second angle, so that the grating compound lens unit forms a different viewpoint.
  • the first grating compound lens sub-region includes a first grating sub-region
  • the second grating compound lens sub-region includes a second grating sub-region
  • the grating period of the first grating sub-area and the grating period of the second grating sub-area are different from each other, and the grating line direction of the grating unit of the first grating sub-area is the same as the grating unit of the second grating sub-area Or the grating line direction of the grating unit of the first grating sub-region and the grating line direction of the grating unit of the second grating sub-region are different from each other, and the grating period of the first grating sub-region It is the same as the grating period of the second grating sub-region.
  • the grating period of the first grating sub-region and the grating period of the second grating sub-region are different from each other; and the grating of the grating unit of the first grating sub-region The line direction and the grating line direction of the grating unit of the second grating sub-region are different from each other.
  • the lens layer includes a plurality of grating compound lens units; the plurality of grating compound lens units includes a first grating compound lens unit and a second grating compound lens unit; In the first grating compound lens unit, the second grating compound lens unit is further away from the center of the lens layer; and the grating period of the second grating compound lens unit is smaller than that of the first grating compound lens unit Grating period.
  • the phase difference value of the grating unit of the second grating compound lens unit is greater than the phase difference value of the grating unit of the first grating compound lens unit;
  • the second grating The phase difference value of the grating unit of the compound lens unit is the difference between the maximum phase of the grating unit of the second grating compound lens unit and the minimum phase of the grating unit of the second grating compound lens unit;
  • the first The phase difference of the grating unit of a grating compound lens unit is the difference between the maximum phase of the grating unit of the first grating compound lens unit and the minimum phase of the grating unit of the first grating compound lens unit.
  • the display pixel set includes at least one display pixel; and the orthographic projection of the display pixel set on the lens layer is located within the grating compound lens unit.
  • the center of the grating composite lens unit and the center of the lens layer are spaced apart; and the display pixels are set on the lens layer and the center of the orthographic projection and the center The centers of the grating compound lens units are substantially coincident.
  • the display layer further includes a space area arranged around the display pixel set and used to space the adjacent display pixel sets, and the space area is configured as a non-display Area; and the display pixel set includes a plurality of the display pixels, the interval area includes a plurality of driving elements, and the plurality of driving elements are used to drive the corresponding set of display pixels.
  • the display device further includes a spacer layer.
  • the spacer layer is arranged between the display layer and the lens layer; the phase distribution of the lens unit Meet the following expressions:
  • R is the vector of the orthographic projection of the center of the lens layer on the spacer layer to a position within the orthographic projection of the grating composite lens unit on the spacer layer
  • R n is the lens layer's orthographic projection.
  • the vector of the orthographic projection of the center on the spacer layer to the orthographic projection of the center of the grating compound lens unit on the spacer layer, f is the focal length of the grating compound lens unit, and n is the refraction of the spacer layer ⁇ is the effective working wavelength of the display device.
  • the phase distribution of the grating unit And grating period P1 respectively satisfy the following expressions:
  • ⁇ is the angle between the vector r n in the field direction of the image center of the grating compound lens unit and the vector t in the normal direction of the spacer layer
  • r // is the image side of the grating compound lens unit The projection vector of the vector r n in the direction of the central field of view on the spacer layer.
  • the grating compound lens unit is at least one of a binary optical lens, a lens based on metasurface phase control, and a lens based on holographic materials.
  • Figure 1A is a schematic cross-sectional view and an optical path diagram of a display device
  • FIG. 1B is a schematic plan view of the display device shown in FIG. 1A;
  • 1C is a simulation diagram of the integrated image of the display pixel by the lens unit in the case of off-axis imaging
  • FIG. 2 is a schematic cross-sectional view of a display device provided by an embodiment of the present disclosure
  • FIG. 3A is a schematic light path diagram of the display device shown in FIG. 2;
  • 3B is a schematic light path diagram of the central lens of the display device shown in FIG. 2;
  • 3C is a schematic light path diagram of the grating compound lens unit of the display device shown in FIG. 2;
  • FIG. 4A is a schematic plan view of a display layer provided by an embodiment of the present disclosure.
  • 4B is a schematic plan view of a display pixel set and spacing area provided by an embodiment of the present disclosure
  • 5A is a schematic plan view of a lens layer provided by an embodiment of the present disclosure.
  • FIG. 5B is a schematic diagram of orthographic projection of the display layer shown in FIG. 4A on the lens layer shown in FIG. 5A;
  • 6A is a schematic plan view of a grating unit provided by an embodiment of the present disclosure.
  • 6B is a schematic plan view of a row of grating units provided by an embodiment of the present disclosure.
  • FIG. 7A is a schematic plan view of another lens layer provided by an embodiment of the present disclosure.
  • FIG. 7B shows a variety of arrangements of multiple viewpoints provided by the display device provided by an embodiment of the present disclosure
  • FIG. 8 is a schematic cross-sectional view of another display device provided by an embodiment of the present disclosure.
  • FIG. 9 is a schematic light path diagram of the display device shown in FIG. 8.
  • 10A is a schematic phase distribution diagram of the lens unit of the grating compound lens unit in FIG. 8;
  • 10B is a schematic phase distribution diagram of the grating unit of the grating compound lens unit in FIG. 8;
  • 10C is a schematic phase distribution diagram of the grating compound lens unit in FIG. 8;
  • 10D is a schematic diagram of the convergence and deflection effect of the grating compound lens unit in FIG. 8 on the light incident thereon;
  • 10E is a simulation diagram of the integrated image of the display pixel by the grating compound lens unit in FIG. 8;
  • 10F is a schematic diagram of the influence of the phase difference value of the grating unit on the deflection of light
  • 11A is a schematic diagram for showing structural parameters of the display device.
  • 11B is a schematic diagram of the orthographic projection of the grating compound lens unit on the spacer layer.
  • FIG. 1A is a schematic cross-sectional view of a display device 500
  • FIG. 1B shows a schematic plan view of the display device 500 shown in FIG. 1A
  • the display device 500 may be used in virtual reality glasses, for example.
  • the display device 500 includes a display layer and a lens layer 520.
  • the display layer includes a display pixel set 510 arranged in an array, and the display pixel set 510 includes at least one display pixel 511.
  • the lens layer 520 includes lens units 521 arranged in an array.
  • the inventor of the present application has noticed in research that in the display device 500 shown in FIGS. 1A and 1B, the center of the orthographic projection of some of the lens units 521 on the display layer and the corresponding display pixel
  • the center of the set 510 is spaced apart, that is, the display pixel set 510 (for example, the center of the display pixel set 510) and the optical axis 530 of the corresponding lens unit 521 are spaced apart.
  • the display pixel set 510 for example, the center of the display pixel set 510
  • the optical axis 530 of the corresponding lens unit 521 are spaced apart.
  • at least a part of the area of the partial display pixel set 510 is arranged outside the orthographic projection of the corresponding lens unit 521 on the display layer, so that the light emitted by different display pixel sets 510 can be transmitted.
  • the corresponding viewpoint for example, the first viewpoint VP1
  • the image points of different display pixel sets 510 can be spliced into the image to
  • FIG. 1C shows a simulation result diagram of a single lens unit 521 imaging the display pixel set 510 in the case of off-axis imaging (10 degrees ⁇ 1.5 degrees).
  • light 552 represents light corresponding to the main viewing angle (10 degrees)
  • light 551 represents light corresponding to the main viewing angle (10 degrees)-1.5 degrees
  • light 553 represents light corresponding to the main viewing angle (10 degrees) + 1.5 degrees.
  • the size of the light spot formed by the light 551, the light 552, and the light 553 on the image surface 550 of the display device 500 are all larger, which means that the off-axis imaging (10 degrees ⁇ 1.5 In the case of degrees), the imaging quality of the display pixel set 510 by the lens unit 521 no longer meets actual application requirements. Therefore, the image-side viewing angle of the display device 500 cannot be increased by arranging more lens units 521, so the overall viewing angle of the display device 500 shown in FIG. 1A is relatively small (for example, less than 10°).
  • the inventor of the present application has noticed in research that the imaging quality of the display device 500 shown in FIG. 1A can be improved by increasing the focal length of the lens unit 521.
  • the focal length of the lens unit 521 increases, the curvature of the lens unit 521 decreases (the radius of curvature increases). Therefore, the thickness of the lens unit 521 varies with position and the phase of the lens unit 521 varies with position. Therefore, the adverse effect of the processing error of the lens unit 521 on the imaging quality will be weakened, and correspondingly, the imaging quality of the lens unit 521 will be improved.
  • the focal length of the lens unit 521 increases, when the angle of view is fixed, when the focal length of the lens unit 521 increases, the distance between the lens unit 521 and the display pixel set 510 increases, and the display pixel set 510 emits and is emitted by the lens.
  • the maximum value of the angle between the light received by the unit 521 and the optical axis of the lens unit 521 is reduced. Therefore, the off-axis degree of imaging of the display pixel set 510 by the lens unit 521 is reduced (that is, closer to paraxial imaging), thereby The imaging quality of the lens unit 521 is improved.
  • the inventor of the present application has noticed that the technical solution of increasing the imaging quality of the display device 500 by increasing the focal length of the lens unit 521 will increase the thickness of the display device 500 (for example, the thickness of the display device 500 is greater than 1 cm), which is different from Consumers' requirements for the display device 500 are in violation.
  • the inventor of the present application has also noticed in research that in the display device shown in FIGS. 1A and 1B, the center of the orthographic projection of the different lens units 521 on the display layer is the same as the center of the corresponding display pixel set 510. The distance between the two is different, which means that the display pixel set 510 is unevenly distributed in the display layer, thereby increasing the difficulty of manufacturing the display layer.
  • At least one embodiment of the present disclosure provides a display device, the display device includes a display layer and a lens layer, the lens layer is disposed on the light exit side of the display layer and includes at least one grating compound lens unit; the display layer includes at least one display pixel
  • the display pixel set is configured to emit light for imaging toward the grating compound lens unit during the display process; the grating compound lens unit is configured to optically image the display pixel set; and the grating compound lens unit is also configured to deflect for imaging The light rays of the grating compound lens unit cross the direction of the optical axis of the grating compound lens unit, so that the display device has one or more viewpoints.
  • the display pixel set can be imaged by using the grating compound lens unit and the light used for imaging can be deflected so that the image center field direction of the grating compound lens unit is the extension direction of the optical axis of the grating compound lens unit.
  • Cross so that the display pixel set can be imaged by paraxial imaging, so the imaging quality of the lens layer to the display layer can be improved, and thus the focal length of the lens layer can be reduced and/or the image side field of view of the display device can be improved .
  • the lens layer includes a plurality of grating compound lens units arranged in an array, and the image center field direction of each grating compound lens unit crosses the extending direction of the optical axis of the grating compound lens unit, thereby making each grating compound lens unit
  • the image center field direction of the grating compound lens unit crosses the imaging optical axis of the entire grating compound lens unit array.
  • the imaging optical axis of the entire grating compound lens unit array refers to the normal line of the lens layer plane passing through the center of the human eye pupil.
  • each grating compound lens unit intersects the same point on the imaging optical axis of the lens layer, and thus forms a viewpoint of the display device.
  • the imaging optical axis of the lens layer is perpendicular to the lens layer.
  • FIG. 2 shows a schematic cross-sectional view of a display device 100 provided by an embodiment of the present disclosure.
  • FIG. 3A is a schematic light path diagram of the display device 100 shown in FIG. 2.
  • the display device 100 can be used in virtual reality glasses, for example.
  • the display device 100 includes a display layer 110 and a lens layer 120, and the lens layer 120 is disposed on the light emitting side of the display layer 110.
  • the display layer 110 and the lens layer 120 are overlapped in the third direction D3.
  • the center 1200 of the lens layer coincides with the orthographic projection of the center 1100 of the display layer on the lens layer 120.
  • the lens layer 120 may include a plurality of lens units (for example, a grating compound lens unit 121).
  • FIG. 4A is a schematic plan view of a display layer 110 provided by an embodiment of the present disclosure.
  • the display layer 110 includes a central display pixel set 113 and a display pixel set 111 arranged in an array around the central display pixel set 113, arranged in an array in a plane parallel to the first direction D1 and the second direction D2;
  • the display pixel set 111 includes at least one display pixel 1111.
  • the number and arrangement of the display pixels included in the central display pixel set 113 may be the same as the number and arrangement of the display pixels 1111 in the display pixel set 111, and will not be repeated here.
  • first direction D1 and the second direction D2 cross each other (eg, perpendicular)
  • third direction D3 crosses the first direction D1 (eg, perpendicular)
  • second direction D2 e.g, perpendicular
  • each display pixel set 111 includes nine display pixels
  • each display pixel set 111 may also include one display pixel, two display pixels, twelve display pixels, or other numbers of display pixels.
  • the resolution and display effect of the display device can be ensured or improved under the condition of a fixed lens unit size, and the manufacturing difficulty of the display device can be reduced (no need to manufacture an undersized lens. unit).
  • the display pixel set 111 includes multiple display pixels, the gray levels of the multiple display pixels can be independently controlled.
  • the intensity of light emitted by the plurality of display pixels 1111 included in each display pixel set 111 may be different from each other, and may be used to form an image sub-region or image sub-picture of the image to be displayed of the display device 100.
  • the image sub-areas formed based on each display pixel set 111 and the image sub-areas formed based on other display pixel sets 111 are combined with each other on the image plane 150 of the display device to form a larger image.
  • the display layer 110 further includes a spacer area 112 arranged around the display pixel set 111 and used to space adjacent display pixel sets 111, and the spacer area 112 is configured as a non-display area.
  • FIG. 4B shows a schematic plan view of a display pixel set 111 and a spacer area 112 provided by an embodiment of the present disclosure.
  • the spacer area 112 includes a plurality of driving elements 1112, and each driving element 1112 may be connected to a corresponding display pixel 1111 through a wire 1113 and used to drive the corresponding display pixel set 111.
  • the driving element 1112 may include a thin film transistor, for example.
  • the display pixel 1111 includes a driving element 1112, that is, the driving element 1112 is disposed in the display pixel set 111.
  • an ordinary display panel can also be used as the display layer 110 of the embodiment of the present disclosure, thereby increasing the selection range of the display panel; in this case, the display pixels 1111 in the interval area 112 are displayed The process is not working.
  • FIG. 5A is a schematic plan view of a lens layer 120 provided by an embodiment of the present disclosure.
  • the lens layer 120 includes a central lens 124 located at the center of the lens layer 120 and a grating compound lens unit 121 arranged in an array around the central lens 124.
  • the center of the central lens 124 coincides with the center 1200 of the lens layer.
  • the center of the grating compound lens unit 121 is spaced apart from the center 1200 of the lens layer.
  • FIG. 5A shows that the lens layer 120 includes a plurality of grating compound lens units 121, according to actual application requirements, the lens layer 120 may also include only one grating compound lens unit 121.
  • the orthographic projections of the central lens 124 and the grating compound lens unit 121 on the display layer 110 are both regular hexagons; in this case, the grating compound lens unit 121 is hexagonal around the central lens 124.
  • the close-packed distribution can improve the space utilization of the display layer 110.
  • the orthographic projection of the central lens 124 and the grating compound lens unit 121 on the display layer 110 may also be a triangle (for example, an equilateral triangle), a rectangle, or other suitable shapes, which will not be repeated here.
  • FIG. 5B shows a schematic diagram of the orthographic projection of the display layer 110 on the lens layer 120.
  • the multiple display pixel sets 111 correspond to the multiple grating compound lens units 121 one-to-one, and the orthographic projection of the multiple display pixel sets 111 on the lens layer 120 is located in the corresponding grating compound lens unit 121; the center display The orthographic projection of the pixel set 113 on the lens layer 120 is located within the central lens 124.
  • the center of the orthographic projection of the central display pixel set 113 on the lens layer 120 substantially coincides with the center of the central lens 124.
  • FIG. 5B shows that the center of the orthographic projection of the central display pixel set 113 on the lens layer 120 substantially coincides with the center of the central lens 124.
  • the center of the orthographic projection of the plurality of display pixel sets 111 on the lens layer 120 substantially coincides with the center of the corresponding grating compound lens unit 121.
  • the center of the orthographic projection of the plurality of display pixel sets 111 on the lens layer 120 and the center of the corresponding grating compound lens unit 121 may completely coincide.
  • the center of the orthographic projection of the plurality of display pixel sets 111 on the lens layer 120 and the center of the corresponding grating compound lens unit 121 may also have a slight difference. Pitch (for example, less than 5% of the size of the display pixel set 111).
  • the fine pitch may reduce (slightly reduce) the imaging quality of the lens layer 120 for the plurality of display pixel sets 111, but the lens layer 120 may reduce the image quality of the plurality of display pixel sets 111.
  • the imaging quality of the pixel set 111 is still greater than that of the ordinary lens layer.
  • FIG. 3B is a schematic light path diagram of the central lens 124 of the display device 100 shown in FIG. 2
  • FIG. 3C is a schematic light path diagram of the grating compound lens unit 121 of the display device 100 shown in FIG. 2.
  • the central display pixel set 113 is configured to emit light for imaging toward the central lens 124 during display.
  • the central lens 124 enables at least part of the light incident on the central lens 124 for imaging to be transmitted to the first viewpoint V1 located on the exit pupil plane of the display device 100, and thereby causes the central display pixel set 113 to emit
  • the imaged light forms an imaging point of the central display pixel set 113 on the image plane 150 of the display device.
  • the image-side center field direction 1242 of the center lens coincides with the optical axis 1241 of the center lens.
  • the first viewpoint V1 is located in the exit pupil of the display device 100, and the diameter of the first viewpoint V1 is, for example, about 0.8-1.5 mm; in some examples, the first viewpoint V1 forms the exit pupil of the display device 100, and in other In the example, the display device 100 has multiple viewpoints, and the first viewpoint V1 and other viewpoints together form the exit pupil of the display device 100.
  • the imaging point may be a single image pixel point, or may be an image sub-region or image sub-picture composed of multiple image pixels.
  • the image center field direction 1242 of the central lens 124 is the transmission direction of the light emitted by the display layer 110 and incident to the optical center of the central lens 214 after leaving the central lens 12.
  • the center of the center display pixel set 113 and the center of the center lens 124 may both be located on the optical axis 1241 of the center lens.
  • the first viewpoint V1 may also be located on the optical axis 1241 of the center lens, thereby improving the quality of the image viewed by the user.
  • the grating compound lens unit 121 includes a lens unit 122 and a grating unit 123.
  • the focal length of the lens unit 122 is, for example, equal to the focal length of the central lens 124.
  • the focal length of the lens unit 122 and the focal length of the central lens 124 are, for example, equal to the lens layer 120.
  • the display pixel set 111 is configured to emit light for imaging toward the grating compound lens unit 121 during the display process.
  • the grating compound lens unit 121 is also configured to deflect light for imaging, so that the image center field direction 1222 of the grating compound lens unit 121 is aligned with the optical axis of the grating compound lens unit 121 (that is, the optical axis 1221 of the lens unit)
  • the extension direction crosses.
  • the optical axis of the grating compound lens unit 121 refers to the optical axis 1221 of the lens unit of the grating compound lens unit 121.
  • the image center field direction 1222 of the grating compound lens unit 121 is the transmission of the light emitted from the display layer 110 and incident to the optical center of the grating compound lens unit 121 after leaving the grating compound lens unit 121. direction.
  • the lens unit 122 is configured to image the display pixel set 111.
  • the image-side center field of view direction of the grating compound lens unit 121 coincides with the optical axis 1221 of the lens unit.
  • the image-side central field of view of the grating compound lens unit 121 without the grating unit 123 is equal to the central field of view of the lens unit 122; for the image-side field of view of the lens unit 122, refer to the dotted line in FIG. 3C.
  • the grating unit 123 is configured to deflect the light used for imaging so that the image center field direction 1222 of the grating compound lens unit 121 deviates from the optical axis 1221 of the lens unit 122.
  • the grating unit 123 is configured to deflect the image-side central field of view direction of the grating compound lens unit 121 (and the corresponding image-side optical path) from the extending direction of the optical axis 1221 of the lens unit 122 to a predetermined field of view direction.
  • the imaging point of the display pixel set 111 and the imaging point of the central display pixel set 113 are spliced into at least part of the image to be displayed of the display device 100.
  • the grating unit 123 is configured to transmit at least part of the light emitted by the display pixel set 111 to the exit pupil of the display device 100 by deflecting the image center field direction 1222 of the grating compound lens unit 121
  • the imaging point of the grating compound lens unit 121 on the display pixel set 111 and the center lens 124 on the center display pixel set 113 can be spliced into at least part of the image to be displayed (for example, in the display device
  • the image plane 150 is spliced into a larger image).
  • the plurality of grating compound lens units 121 can view the center of the corresponding image side.
  • the field direction is deflected by a predetermined angle, so that the multiple imaging points of the multiple grating compound lens units 121 on the corresponding display pixel set 111 and the central lens 124 on the central display pixel set 113 can be spliced into a to-be-displayed image.
  • the plurality of grating units 123 of the plurality of grating compound lens units 121 are configured to deflect at least part of the light emitted by the plurality of display pixel sets 111 by deflecting the image center field direction 1222 of the corresponding grating compound lens unit 121
  • the first viewpoint V1 is located on the exit pupil plane of the display device 100 (for example, the image-side center field of view direction 1222 of the plurality of grating compound lens units 121 all pass through the first viewpoint V1), thereby making the plurality of grating compound lens units
  • the imaging point of the corresponding display pixel set 111 of 121 and the imaging point of the center display pixel set 113 of the center lens 124 can be spliced into an image to be displayed.
  • the image points of the adjacent display pixel sets 111 are close to each other, thereby forming a continuous picture without overlap.
  • the display pixels 1111 with a small size can be selected, and correspondingly, the lens unit 122 with a larger magnification can be selected, which will not be repeated here.
  • the imaging of the central display pixel set 113 by the central lens 124 is paraxial imaging, but the imaging of the display pixel set 111 by the grating compound lens unit 121 is also paraxial imaging. Therefore, the imaging quality of the lens layer 120 is improved. Therefore, compared with the off-axis imaging solution adopted by the display device 100 shown in FIG. 1A and FIG. 1B, the grating compound lens unit 121 can reduce the imaging aberration of the lens layer 120 and improve the effect of the lens layer 120 on the display pixel set 111. Image quality.
  • the grating compound lens unit 121 can increase the image-side field angle of the lens layer 120 (for example, increase the image-side field angle of the lens layer 120 to more than ⁇ 60° );
  • the focal length of the lens layer 120 can be reduced (for example, the focal length of the lens layer 120 is less than 1 mm), thereby reducing the thickness of the display device 100 and improving the user experience.
  • the focal length of the lens layer 120 is less than 1 mm
  • the display pixels 1111 can be evenly arranged on the display layer 110, thus not only can reduce the design and manufacturing difficulty of the display layer 110, but also The alignment difficulty of the display layer 110 and the lens layer 120 can be reduced.
  • the paraxial imaging of the lens means that the angle ⁇ between the light used for imaging and the optical axis of the lens is small, and the following approximate conditions sin ⁇ and cos ⁇ 1; for example, ⁇ 3°.
  • the imaging of the display pixel set 111 by the grating compound lens unit 121 is paraxial imaging means that the angle between the light in the object field of view of the grating compound lens unit 121 and the optical axis of the lens is small.
  • the lens unit 122 and the grating unit 123 may be attached to each other and overlapped on the light emitting side of the display layer 110.
  • the lens unit 122 is closer to the display layer 110 than the grating unit 123.
  • the grating unit 123 will not affect the object field of view of the grating compound lens unit 121. Therefore, the imaging quality of the grating compound lens unit 121 can be further improved.
  • FIG. 6A is a schematic plan view of a grating unit 123 provided by an embodiment of the present disclosure.
  • the grating unit 123 includes a plurality of grating lines 1231, and the orientation directions (ie, extending directions) of the plurality of grating lines 1231 are parallel to each other, and the angle between the grating lines 1231 of the grating unit 123 and the second direction D2 (Acute angle) is the orientation angle of the grating unit 123; the pitch between adjacent grating lines 123 (the pitch perpendicular to the extending direction of the grating line 1231) is the grating period of the grating unit 123.
  • At least one grating compound lens unit 121 of the lens layer 120 includes a first grating compound lens unit and a second grating compound lens unit; compared to the first grating compound lens unit, the second grating compound lens unit is farther away from the lens layer.
  • the grating period of the second grating compound lens unit is smaller than the grating period of the first grating compound lens unit, so that the center field direction of the second grating compound lens unit is aligned with the optical axis of the lens unit of the second grating compound lens unit
  • the included angle is greater than the angle between the image center field direction of the first grating compound lens unit and the optical axis of the lens unit of the first grating compound lens unit, so that the display pixel set 111 corresponding to the second grating compound lens unit emits At least part of the light and at least part of the light emitted by the display pixel set 111 corresponding to the first grating compound lens unit can be transmitted to the first viewpoint V1 located on the exit pupil plane of the display device 100.
  • FIG. 6B is a schematic plan view of a row of grating units 123 provided by an embodiment of the present disclosure.
  • the second grating compound lens unit is further away from the center 1200 of the lens layer; and the grating period of the grating unit 1252 included in the second grating compound lens unit is smaller than the grating period of the grating unit 1251 included in the first grating compound lens unit.
  • the smaller the grating period the larger the diffraction angle.
  • the light deflection angle of the grating unit 1252 included in the second grating compound lens unit is greater than the light deflection angle of the grating unit 1251 included in the first grating compound lens unit, and thus the image center field of view direction of the second grating compound lens unit
  • the included angle with the optical axis of the lens unit of the second grating compound lens unit is greater than the angle between the image center field direction of the first grating compound lens unit and the optical axis of the lens unit of the first grating compound lens unit;
  • at least part of the light emitted by the display pixel set 111 corresponding to the second grating compound lens unit and at least part of the light emitted by the display pixel set 111 corresponding to the first grating compound lens unit can be transmitted to the display device 100.
  • the imaging points of can be spliced into at least part of the image to be displayed (for example, at least part of the image to be displayed can be spliced on the image plane 150 of the display device).
  • the grating period of the grating unit 123 of the grating compound lens unit 121 may be gradually reduced, so that the grating period along the center of the lens layer 120 faces the edge of the lens layer 120.
  • the deflection angle of the image-side center field of view of the grating compound lens unit 121 gradually increases, and the imaging points of the plurality of grating compound lens units 121 to the corresponding display pixel set 111 and the central lens 124 to the center display pixel set 113 is spliced into an image to be displayed (for example, a continuous and non-overlapping image).
  • the grating compound lens unit 121 may form multiple viewpoints by imaging the display pixel set 111, which will be exemplified below with reference to FIGS. 7A and 7B.
  • FIG. 7A shows a plurality of grating compound lens unit sub-regions of the grating compound lens unit 121
  • FIG. 7B shows a plurality of viewpoints formed by the grating compound lens unit 121
  • the grating compound lens unit 121 may include multiple grating compound lens unit sub-regions (sub-region 1, sub-region 2, ..., sub-region n), and the multiple grating compound lens unit sub-regions are configured To form a plurality of viewpoints (viewpoint 1, viewpoint 2, ..., viewpoint n) based on light incident on the grating compound lens unit 121.
  • multiple grating compound lens unit sub-regions can be configured to form n viewpoints as shown in FIG.
  • images corresponding to n viewpoints may be the same image, that is, images corresponding to different viewpoints have the same color and gray scale. distributed.
  • the user can continue to watch the image displayed by the display device 100, that is, the grating compound lens unit 121 shown in FIG. 7A can increase the observation area of the display device 100 ( eye box) or observation window, and therefore can enhance the user experience.
  • the shape of the sub-areas of the grating compound lens unit, the arrangement of the multiple grating compound lens unit sub-areas in the grating compound lens unit 121, and the arrangement of multiple viewpoints can be set according to actual application requirements.
  • the embodiment does not specifically limit this.
  • the sub-region of the grating compound lens unit may be a triangle, and one vertex of the triangle coincides with the center of the grating compound lens unit 121.
  • the grating compound lens unit 121 may include six, twelve, eighteen, or other suitable number of grating compound lens unit sub-regions, which will not be repeated here. It should be noted that in the case where the shape of the grating compound lens unit 121 is other shapes, the sub-region of the grating compound lens unit can be set with reference to FIG. 7A, which will not be repeated here.
  • the arrangement of n viewpoints formed by the grating compound lens unit 121 may be a row arrangement (that is, the n viewpoints are arranged in a row), a cross-shaped arrangement (that is, n The viewpoints are arranged in a row and a column perpendicular to each other), matrix arrangement, rice-shaped arrangement, or other suitable arrangement methods, which will not be repeated here.
  • the distance between adjacent viewpoints is smaller than the pupil diameter, so that the light field display can be realized while the adjacent viewpoints (different viewpoints) are loaded with corresponding light field images; in other examples
  • the distance between adjacent viewpoints can also be greater than the pupil diameter, so that the expansion of the observation window (observation area) of the human eye can be realized when the adjacent viewpoints (different viewpoints) are loaded with the same image respectively.
  • it can also have the expansion effect of the human eye observation window.
  • the principle of multiple viewpoints formed by the grating compound lens unit 121 will be exemplarily described below.
  • the grating unit 123 includes a first grating sub-region and a second grating sub-region
  • the lens unit 122 includes a first lens sub-region corresponding to the first grating sub-region and a second lens sub-region corresponding to the second grating sub-region
  • the first grating sub-region and the first lens sub-region are combined with each other to form a first grating composite lens unit sub-region
  • the second grating sub-region and the second lens sub-region are combined with each other to form a second grating composite lens unit sub-region.
  • the light rays used for imaging emitted by the display pixel set 111 include the first light rays incident on the first lens sub-region and the first grating sub-region and the second light rays incident on the second lens sub-region and the second grating sub-region;
  • the first lens sub-area is configured to image the display pixel set 111 based on the first light
  • the second lens sub-area is configured to image the display pixel set 111 based on the second light
  • the first grating sub-area is configured to image the grating compound lens unit 121
  • the image center field direction of the area corresponding to the first grating sub-region that is, the first grating compound lens sub-region
  • the area is configured to deviate the image center field direction of the area of the grating compound lens unit 121 corresponding to the second grating sub-area (that is, the second grating
  • the grating period of the first grating sub-region, the grating period of the second grating sub-region, the grating line 1231 direction of the grating unit 123 of the first grating sub-region and the grating line of the grating unit 123 of the second grating sub-region can be adjusted.
  • At least one of the 1231 directions is such that the field direction of the image center of the grating compound lens unit 121 corresponding to the first grating sub-region and the image center of the grating compound lens unit 121 corresponding to the second grating sub-region The direction of the field of view is deflected by different angles.
  • the grating period of the first grating sub-area and the grating period of the second grating sub-area are different from each other, and the grating line 1231 direction of the grating unit 123 of the first grating sub-area is the same as the grating line of the grating unit 123 of the second grating sub-area.
  • the direction of 1231 is the same.
  • the grating line 1231 direction of the grating unit 123 of the first grating sub-region and the grating line 1231 direction of the grating unit 123 of the second grating sub-region are different from each other, and the grating period of the first grating sub-region is different from that of the second grating sub-region.
  • the grating period is the same.
  • the grating period of the first grating sub-region and the grating period of the second grating sub-region are different from each other, and the grating line 1231 direction of the grating unit 123 of the first grating sub-region and the grating unit 123 of the second grating sub-region are different from each other.
  • the directions of the grating lines 1231 are different from each other.
  • the implementation of the display layer 110 and the color display are exemplarily described below.
  • the display layer 110 may be implemented as a self-luminous display panel (for example, an organic light-emitting display panel), a liquid crystal display panel, or other suitable display panels.
  • the display layer 110 may be used to output a monochrome image.
  • the display layer 110 may also be used to output color images.
  • any one of the following two methods can be used to display a color image.
  • the display layer 110 may include a first display pixel for emitting light having a first color, a second display pixel for emitting light having a second color, and a second display pixel for emitting light having a third color.
  • the third display pixel of the light, the first color, the second color, and the third color are, for example, red, green, and blue.
  • the first display pixel, the second display pixel, and the third display pixel may correspond to the same grating compound lens unit 121.
  • the grating compound lens unit 121 includes a lens unit 122, a first grating sublayer, and a second The grating sub-layer and the third grating sub-layer, for example, the orthographic projections of the first grating sub-layer, the second grating sub-layer, and the third grating sub-layer on the display layer 110 completely overlap; the first grating sub-layer and the second grating sub-layer
  • the working wavelengths of the layer and the third grating sub-layer correspond to the first color, the second color, and the third color, respectively.
  • the grating composite lens unit 121 can make the light of different colors have the same deflection angle, thereby suppressing or Eliminate the ghosting problem caused by dispersion (different colors of light have different exit angles).
  • the first grating sub-layer, the second grating sub-layer, and the third grating sub-layer have no deflection effect on the light whose wavelength is the non-operating wavelength.
  • the first grating sublayer does not have a deflecting effect on the light of the second color and the third color.
  • the first display pixel, the second display pixel, and the third display pixel may also correspond to three different grating compound lens units 121 respectively, so that the output of the first display pixel, the second display pixel, and the third display pixel
  • the light can be directly imaged by different grating compound lens units 121, and the light output by the first display pixel, the second display pixel and the third display pixel (multiple first display pixels, second display pixels, and third display pixels) can be Superimposed on the virtual image surface to form a complete color picture without ghosting or crosstalk.
  • the display layer 110 includes a timing backlight source and a light enhancement layer.
  • the timing backlight source has light sources of three colors (such as light-emitting diodes (LED)), which can emit light sequentially during the display period of one frame of image.
  • the emphasis system outputs light of the first color, light of the second color, and light of the third color.
  • the light enhancement layer modulates the light of the first color, the light of the second color and the light of the third color respectively to form the first
  • the middle picture of the color, the middle picture of the second color and the middle picture of the third color the user's eyes can feel the color picture by synthesizing the middle picture of the first color, the middle picture of the second color and the middle picture of the third color.
  • an applicable method for example, a grating compound lens unit formed by a stacked lens unit, a first grating sublayer, a second grating sublayer, and a third grating sublayer
  • a grating compound lens unit formed by a stacked lens unit, a first grating sublayer, a second grating sublayer, and a third grating sublayer can also be used to suppress Or to eliminate the ghosting problem caused by the dispersion of the grating compound lens unit, which will not be repeated here.
  • the grating compound lens unit of the display device provided by the embodiment of the present disclosure is not limited to include discrete grating units and lens units. According to actual application requirements, the grating compound lens unit of the display device provided by the embodiments of the present disclosure may further include an integrated grating unit and a lens unit. An exemplary description will be given below in conjunction with FIG. 8 and FIG. 9.
  • FIG. 8 shows a schematic cross-sectional view of another display device 200 provided by an embodiment of the present disclosure.
  • FIG. 9 is a schematic light path diagram of the display device 200 shown in FIG. 8.
  • the display device 200 can be used in virtual reality glasses, for example.
  • the display device 200 includes a display layer 210 and a lens layer 220.
  • the center of the lens layer 220 may coincide with the orthographic projection of the center of the display layer 210 on the lens layer 220.
  • the display layer 210 includes a central display pixel set 213 and a display pixel set 211 arranged in an array around the central display pixel set 213.
  • the display pixel set 211 includes at least one display pixel.
  • the central display pixel set 213 is arranged in a similar manner It is the setting method of the display pixel set 211.
  • the specific arrangement of the display pixel layer can be referred to the example shown in FIG. 2, which will not be repeated here.
  • the lens layer 220 includes a central lens 224 and a plurality of grating compound lenses 221 arranged in an array around the central lens 224.
  • the lens layer 220 may also include only one grating compound lens. 221, I won't repeat it here.
  • the center of the central lens 224 may coincide with the center of the lens layer 220. In this case, the center of the grating compound lens unit 221 is spaced apart from the center of the lens layer 220.
  • the multiple display pixel sets 211 correspond to the multiple grating compound lens units 221 one-to-one, and the orthographic projection of the multiple display pixel sets 211 on the lens layer 220 is located in the corresponding grating compound lens unit 221; the center display The orthographic projection of the pixel set 213 on the lens layer 220 is located within the central lens 224.
  • the center of the orthographic projection of the central display pixel set 213 on the lens layer 220 substantially coincides with the center of the central lens 224, and the center of the orthographic projection of the plurality of display pixel sets 211 on the lens layer 220 corresponds to The centers of the grating compound lens unit 221 substantially coincide.
  • the central display pixel set 213 is configured to emit light for imaging toward the optical center lens 224 during display.
  • the central lens 224 enables at least part of the light incident on the central lens 224 for imaging to be transmitted to the first viewpoint V1 located on the exit pupil plane of the display device 200, and thereby causes the central display pixel set 213 to emit for imaging.
  • the light ray forms the imaging point of the central display pixel set 213 on the image surface of the display device 200.
  • the image-side center field of view direction 2242 of the central lens 224 coincides with the optical axis 2241 of the central lens.
  • the center of the center display pixel set 213 and the center of the center lens 224 may both be located on the optical axis 2241 of the center lens.
  • the first viewpoint V1 can also be located on the optical axis 2241 of the central lens. In this case, the user can see a more symmetrical image, which can improve the image observed by the user. the quality of.
  • the display pixel set 211 is configured to emit light for imaging toward the grating compound lens unit 221 during the display process.
  • the grating compound lens unit 221 includes a lens unit and a grating unit. As shown in FIGS. 8 and 9, the lens unit and the grating unit are integrated into a phase-type lens, and the phase-type lens is configured while imaging the display pixel set 211
  • the light used for imaging is deflected so that the image-side central field of view direction 2212 of the grating compound lens unit 221 intersects with the extending direction of the optical axis of the grating compound lens 221 (for example, so that the image-side central field of view of the grating compound lens unit 221
  • the direction 2212 passes through the first viewpoint V1), so that the imaging point of the display pixel set 211 and the imaging point of the central display pixel set 213 can be spliced into at least part of the image to be displayed of the display device 200.
  • the phase-type lens is configured to image the light emitted by the display pixel set and at the same time deviate the image-side center field of view direction of the grating compound lens unit from the optical axis of the lens unit.
  • the lens unit, the grating unit, and the grating compound lens unit 221 will be described below with reference to FIGS. 10A-10E.
  • Fig. 10A exemplarily shows the phase distribution of the lens unit included in the grating compound lens unit 221 in Fig. 9 (the z-axis represents the phase of the lens unit).
  • FIG. 10B exemplarily shows the phase distribution of the grating unit included in the grating compound lens unit 221 in FIG. 9 (the z-axis represents the phase of the grating unit).
  • the grating unit can deflect light incident thereon.
  • FIG. 10C exemplarily shows the phase distribution of the grating compound lens unit 221 in FIG. 9 (the z axis represents the phase of the grating compound lens unit), and FIG. 10D exemplarily shows the phase distribution of the grating compound lens unit 221 in FIG. 9 Light path diagram.
  • the grating compound lens unit 221 can collimate (or converge) the divergent light incident thereon while deflecting the light, thereby making the image center field of view direction 2212 of the grating compound lens unit 221 It crosses the extending direction of the optical axis of the grating compound lens 221.
  • FIG. 10E exemplarily shows a simulation diagram (using ZEMAX simulation software) of imaging the display pixel set 211 by the grating compound lens unit 221 in FIG. 9.
  • Light 252 represents light corresponding to the main viewing angle
  • light 251 represents light corresponding to the main viewing angle (10 degrees)-3 degrees
  • light 253 represents light corresponding to the main viewing angle (10 degrees) + 3 degrees.
  • the light spot size on the image surface corresponding to the same viewing angle is small.
  • FIG. 10E shows that the light spot size on the image surface corresponding to the same viewing angle is small.
  • the size of the light spot formed by the light 251, the light 252, and the light 253 on the image surface is small, which indicates that the grating compound lens unit 221 of the display device 200 provided by the embodiment of the present disclosure can make a certain larger
  • the imaging in the range near the center of the viewing angle has the imaging quality of paraxial imaging.
  • the grating compound lens unit 221 of the display device 200 provided by the embodiment of the present disclosure can convert the off-axis imaging in the display device 200 shown in FIG. 1A into paraxial imaging, thereby improving the imaging quality of the display device 200.
  • FIG. 10F shows the influence of the phase difference value of the grating unit on the deflection of light, where the phase difference value of the grating unit refers to the difference between the maximum phase and the minimum phase of the grating unit.
  • the phase difference of the grating unit When increasing, the deflection angle ⁇ dt of the grating unit to the light is larger. This is because the larger the deflection angle ⁇ dt of the light, the phase difference of the light transmission path caused by the light deflection The larger the phase difference of the transmission path Can compensate for the phase difference of the grating unit
  • the phase difference value in the grating unit The greater the value, the greater the phase difference value of the grating composite lens unit 221, the greater the deflection angle of the grating composite lens unit 221 to the emitted light of the corresponding display pixel set 211.
  • the phase difference value of the grating unit of the grating compound lens unit 221 may be gradually increased, In this way, in the direction from the center of the lens layer 220 toward the edge of the lens layer 220, the deflection angle of the image center field of the grating compound lens unit 221 gradually increases, and the multiple grating compound lens units 221 can be adjusted to the corresponding display pixels.
  • the imaging point of the set 211 and the center lens 224 are spliced to the center display pixel set 213 to form an image to be displayed (for example, a continuous image without overlap). The following is an exemplary description with reference to FIG. 9.
  • the plurality of grating compound lens units 221 can view the center of the corresponding image side.
  • the field direction is deflected by a predetermined angle, for example, so that the image-side central field of view direction 2212 of each grating compound lens unit 221 passes through the first viewpoint V1.
  • the image center field direction 2212 of different grating compound lens units 221 have different predetermined deflection angles.
  • the imaging points of the two display pixel sets 211 and the central lens 224 can be joined to the central display pixel set 213 to form an image to be displayed.
  • the imaging points of adjacent display pixel sets 211 are adjacent to each other to form a continuous picture without overlap.
  • the deflection angle of the imaging point of the corresponding display pixel set 211 can be controlled by setting the phase difference value of the grating compound lens unit 221.
  • the phase difference value of the grating compound lens unit 221 refers to the phase difference value of the grating compound lens unit 221.
  • the angle between the image center field direction 2212 of the grating compound lens unit 221 and the optical axis of the lens unit of the grating compound lens unit 221 is larger (also That is, the larger the deflection angle of the image-side center field of view direction 2212 of the grating composite lens unit 221).
  • the phase difference value of the grating composite lens unit 221 can be gradually increased, so that in the direction along the center of the lens layer 220 toward the edge of the lens layer 220, the grating
  • the angle between the image center field direction 2212 of the compound lens unit 221 and the optical axis of the lens unit of the grating compound lens unit 221 gradually increases (that is, the deflection angle of the image center field direction 2212 of the grating compound lens unit 221 Gradually increase), and then the imaging points of the multiple grating compound lens units 221 on the corresponding display pixel set 211 and the central lens 224 on the central display pixel set 213 can be spliced into a to-be-displayed image (for example, a continuous image without overlapping Screen).
  • the imaging of the central display pixel set 213 by the central lens 224 is paraxial imaging, but the imaging of the display pixel set 211 by the grating compound lens unit 221 is also paraxial imaging. , Thereby improving the imaging quality of the lens layer. Therefore, compared to the off-axis imaging solution adopted by the display device 200 shown in FIG. 1A and FIG. 1B, the grating compound lens unit 221 can reduce the imaging aberration of the lens layer 220 and improve the effect of the lens layer 220 on the display pixel set 211. Image quality.
  • the grating compound lens unit 221 can increase the image-side field of view of the lens layer 220 (for example, increase the image-side field of view of the lens layer 220 to more than ⁇ 60°)
  • the focal length of the lens layer 220 can be reduced (for example, less than 1 mm), which can reduce the thickness of the display device 200 and improve the user experience.
  • the display pixels can be evenly arranged on the display layer 210. Therefore, the design and production difficulty of the display layer 210 can be reduced, and the display layer 210 and the lens can be reduced. Difficulty of alignment of layer 220.
  • the display device 200 further includes a spacer layer disposed between the display layer 210 and the lens layer 220.
  • the spacer layer may be a spacer substrate; for another example, the spacer layer may also be an air layer.
  • the lens layer 220 and the display layer 210 are stacked on each other in a frame-attached manner.
  • the orthographic projection of the grating compound lens unit 221 on the spacer layer is a hexagon, but the embodiment of the present disclosure is not limited to this. According to actual application requirements, the orthographic projection of the grating compound lens unit 221 on the spacer layer is It can also be triangular or other suitable shapes.
  • phase distribution of the lens unit Phase distribution of grating unit
  • the grating period P1 and the phase distribution of the grating compound lens unit 221 The following expressions can be satisfied respectively:
  • R is the vector of the orthographic projection of the center of the lens layer 220 on the spacer layer to a position within the orthographic projection of the grating composite lens unit 221 on the spacer layer
  • R n is the center of the lens layer 220 on the spacer layer.
  • Orthographic projection to the vector of the orthographic projection of the center of the grating compound lens unit 221 on the spacer layer f is the focal length of the grating compound lens unit 221, n is the refractive index of the spacer layer, ⁇ is the effective working wavelength of the display device 200; ⁇ is The angle between the vector r n in the image center field direction 2212 of the grating compound lens unit 221 and the vector t in the normal direction of the spacer layer, r // is the vector in the image center field direction 2212 of the grating compound lens unit 221 The projection vector of r n on the spacer layer.
  • the phase distribution of the lens unit It can be used to realize the spherical aberration-free convergence or collimation of the plane wave by the grating compound lens unit 221.
  • the phase distribution of the lens unit Used to make up for the difference in optical path length of different light rays incident on different positions of the lens unit due to different transmission paths, so that different light rays emitted from the display layer 210 and incident on different positions of the lens unit go through the same optical path .
  • the phase distribution of the grating unit It is used to deflect the light incident thereon, so that the grating compound lens unit 221 can deflect the light while collimating the light incident thereon, thereby making the image center field of view of the grating compound lens unit 221
  • the direction 2212 crosses the extending direction of the optical axis of the grating compound lens 221.
  • the grating compound lens unit 221 can deflect the image-side optical path to a predetermined field of view to convert different display pixel sets 211
  • the imaging point of ⁇ and the imaging point of the central display pixel set 213 are spliced to form an image to be displayed (spliced on the image plane 250 of the display device).
  • the imaging quality of the lens layer 220 can be improved, but also the image-side field of view of the display device 200 can be increased and/or the size of the display device 200 can be reduced.
  • the aberration correction phase in addition to introducing the phase of the grating unit into the grating compound lens unit 221, according to actual application requirements, can also be used in the grating compound lens unit 221, thereby further improving the grating compound lens.
  • the aberration correction phase can be expressed using Zernike polynomials (Zernike polynomials).
  • Zernike polynomials Zernike polynomials
  • an applicable Zernike polynomial can be selected based on the type of aberration desired to be corrected, and the phase corresponding to the Zernike polynomial can be introduced into the grating compound lens unit 221.
  • the relationship between Zernike polynomials and aberrations can be found in related technologies, which will not be repeated here.
  • the lens unit and the grating unit can be integrally formed into a phase grating compound lens unit 221, which is an integrated phase type grating lens unit 221 compared to the separate lens unit and grating unit.
  • the grating compound lens unit 221 can better control the convergence angle (the difference between the divergence angle of the light incident on the grating compound lens unit 221 and the divergence angle of the light emitted from the grating compound lens unit 221) and the deflection angle, thereby The imaging effect can be further improved.
  • phase of the lens unit and the phase of the grating unit can be introduced into the material of the phase grating compound lens unit 221 at the same time, so that the lens unit and the grating unit can be integrated into the phase grating compound lens unit 221.
  • the grating compound lens unit 221 may be implemented as a planar lens.
  • the planar lens in the embodiments of the present disclosure refers to a lens that can realize an imaging function without using the curved surface of a common geometric lens.
  • the grating compound lens unit 221 based on a flat lens is not limited by factors such as lens surface shape and material refractive index like ordinary geometric lenses, so the design flexibility of the grating compound lens unit 221 can be improved.
  • a planar lens can realize imaging without aberration (for example, no spherical aberration), and thus the grating compound lens unit 221 based on the planar lens can further improve the imaging quality of the lens layer 220.
  • the surface of the flat lens may have a stepped structure with a small size, but does not have a curved surface type.
  • the flat lens may be a binary optical lens.
  • the surface of the flat lens may be a flat surface, for example, the flat lens may be a lens based on a metasurface phase adjustment or a lens based on a holographic material.
  • the grating compound lens unit 221 is implemented as a binary optical lens, for example, a multi-step structure overprinting (that is, multiple etching) or an imprinting process (the phase order is for example N, when using In the case of the overlay process, the number of processes is, for example, log 2 N), and the thickness of the lens layer 220 is, for example, 5-10 microns (the size of a typical phase modulation unit is on the order of microns).
  • binary optical lenses are generally insensitive to polarization, they can modulate natural light.
  • a display panel with a narrow emission spectrum can be selected as the display layer 210.
  • the grating compound lens unit 221 is implemented as a lens based on metasurface phase adjustment (for example, a super lens, Metalens), it may be based on at least one of a semiconductor manufacturing process (for example, a single photolithography process and a single imprint).
  • a semiconductor manufacturing process for example, a single photolithography process and a single imprint.
  • the lens layer 220 is made.
  • the lens layer 220 may have a flat plate shape.
  • the grating compound lens unit 221 based on metasurface phase control has the following characteristics: the phase modulation accuracy of the grating compound lens unit is high (for example, because the scale of the phase modulation unit is sub-wavelength order), it can further reduce the grating compound The aberration of the lens unit 221; the thickness of the grating compound lens unit is small (the thickness of the grating compound lens unit 221 is on the order of subwavelength), which can further reduce the thickness of the display device 200; the phase adjustment is realized based on polarization, so you can choose
  • the display panel that outputs circularly polarized light or linearly polarized light is used as the display layer 210; the dispersion controllability is better (compared to the conventional binary optical diffractive device), so the requirement for the spectral width of the light output from the display layer 210 is lower.
  • the display layer 210 can be a display panel such as OLED, micro LED, quantum dot LCD, etc., and includes a device for performing polarization
  • the grating compound lens unit 221 has the following characteristics, for example.
  • the phase modulation accuracy of the grating compound lens unit 221 is high (theoretically, it can be close to continuous modulation), so the aberration of the grating compound lens unit 221 can be further reduced.
  • the thickness of the grating compound lens unit 221 is small, which can reduce the thickness of the display device 200 better.
  • the thickness of the grating compound lens unit 221 is about 2-20 microns.
  • the corresponding refractive index modulation degree is relatively high (for example, 0.2).
  • the grating compound lens unit 221 can be realized by forming a Bragg volume grating structure, thereby improving the efficiency (for example, diffraction efficiency) of the grating compound lens unit 221; at this time, a predetermined exposure light source can be used to form the required phase distribution in advance.
  • the grating compound lens unit 221 has chromatic dispersion. Therefore, the display layer 210 can be selected from display panels such as OLED, micro LED, quantum dot LCD, and the like. In the case of using polarization-sensitive materials to make the grating compound lens unit 221, the display layer 210 also includes a device for performing polarization modulation processing on the light output from the display panel.
  • the exit pupil distance d of the display device 200 is, for example, about 10-14 mm (for example, 12 mm).
  • the diameter D of the grating compound lens unit 221 can be set based on the diffraction angle of the grating compound lens unit 221 and the angular resolution of the human eye (for example, 2').
  • the diameter of the grating compound lens unit 221 is, for example, 1-2. Mm (for example, greater than 1.15 mm).
  • the diameter D of the grating compound lens unit 221 refers to the normal position that can surround the grating compound lens unit 221 on the display layer 210.
  • the focal length of the grating compound lens unit 221 is approximately equal to the diameter D of the grating compound lens unit 221. Therefore, the F number (f/D) of the grating compound lens unit 221 and the thickness of the display device 200 are approximately equal to one.
  • the object distance l o , image distance l img and focal length of the grating compound lens unit 221 satisfy the following expressions:
  • the image distance l img of the grating composite lens unit 221 is, for example, 1-6 meters (for example, 2 meters).
  • the object distance l o of the grating composite lens unit 221 is approximately equal to the focal length f of the lens.
  • the focal length f of the grating compound lens unit 221 is equal to the distance between the display layer 210 and the lens layer 220.
  • the above description is based on the display layer including a display pixel set located in the center of the display layer and a display pixel set arranged in an array around the center display pixel set, and the lens layer includes a central lens located in the center of the lens layer and a display pixel set surrounding the lens layer.
  • the grating compound lens unit arranged in the central lens array is taken as an example to illustrate the embodiments of the present disclosure, but the embodiments of the present disclosure are not limited thereto.
  • the display layer may not be provided with a central display pixel set, and the lens layer may not be provided with a central lens (for example, the lens layer only includes a grating compound lens unit and any two adjacent grating compound lens units are connected to each other)
  • the grating unit in the grating compound lens unit is configured to deflect light for imaging, so that the image center field of view directions of different grating compound lens units can pass through the same point (for example, through the first One viewpoint V1), therefore, the image points of different display pixel sets can be spliced into a to-be-displayed image, so that, for example, each display pixel set can be imaged in a paraxial imaging manner.
  • the lens layer may further include a grating unit corresponding to the central lens, and the grating unit corresponding to the central lens is stacked with the lens layer, for example; in this case, the light incident on the central lens will be incident after leaving the central lens.
  • the grating unit corresponding to the central lens deflects the light rays leaving the central lens and incident on the grating unit corresponding to the central lens.
  • the lens layer may not include a grating unit corresponding to the central lens. In this case, the light incident on the central lens will be directly transmitted to the position of the viewpoint of the display device after leaving the central lens.
  • the center of the lens layer is configured as the optical center of the display device.
  • the center of the lens layer can be used as a reference.
  • the orthographic projection of the viewpoint of the display device on the lens layer may coincide with the center of the lens layer.
  • the center of the lens layer may be the center of the physical structure of the lens layer to improve the display image quality of the display device as much as possible; for another example, the center of the lens layer may not be the center of the physical structure of the lens layer.
  • the lens layer includes a center lens
  • the center of the lens layer and the center of the center lens coincide with each other.
  • Figure 3A- Figure 3C and Figure 9 shows the angle range of the light rays emitted by the entire display pixels included in the display pixel set that reach the human eye through the corresponding grating compound lens unit (that is, the light rays emitted from the grating compound lens unit are incident on the human eye).
  • Figures 3A-3C and Figure 9 give the illusion of converging light to the human eye (that is, the light incident to the human eye is not a converging light).
  • the divergence angle of the light emitted from the grating compound lens unit is smaller than the divergence angle of the light incident on the grating compound lens unit emitted by the display pixel set. Therefore, the image plane of the display device is located on the light emitting surface of the display layer, which is far from the lens layer. Side (for example, the side of the display layer away from the lens layer).
  • the divergence angle of the light emitted from the grating compound lens unit may be close to zero.
  • the image plane (the image plane of the virtual image) of the display device may be located at infinity.
  • the grating compound lens unit has a converging effect.
  • the grating compound lens unit has a converging effect, which means that the grating compound lens unit can make the divergence angle of the light emitted from the grating compound lens unit smaller than the divergence angle of the light incident on the grating compound lens unit from the display pixel set, and It does not mean that the grating compound lens unit has the light emitted from the grating compound lens unit to be a convergent light.
  • FIG. 10D an example of the condensing and deflecting effects of the grating compound lens unit on the light incident thereon can be seen in FIG. 10D.
  • the viewpoint of the display device may be the center of a virtual window (observation area) for human eye observation.
  • the user's eyes When the user's eyes are located at the viewpoint of the display device, the user can observe the image displayed by the display device.
  • the grating compound lens unit is configured to perform appropriate paraxial or off-axis optical imaging on the display pixel set to expand the angle of the overall imaging field of view of the lens layer, thereby improving the user experience.
  • the field of view direction of the image center of the grating compound lens unit is the transmission direction of the light emitted from the display pixel set and incident to the optical center of the grating compound lens unit after leaving the grating compound lens unit.
  • the image center field direction of the grating compound lens unit is the viewpoint of the display device (that is, the corresponding viewpoint in front of the human eye) and the grating compound lens The extension direction of the line between the optical centers of the unit.
  • the image center field of view direction of the grating compound lens unit is the line between the viewpoint of the display device and the optical center of the grating compound lens unit corresponding to a certain pixel point on the virtual image plane relative to the viewpoint of the display device (that is, The direction of the corresponding viewpoint in front of the human eye.
  • the optical axis of the grating compound lens is the optical axis of the lens unit of the grating compound lens unit.
  • the embodiment of the present disclosure provides a display device.
  • the display pixel set can be imaged by using the grating compound lens unit and the light used for imaging can be deflected so that the image center field direction of the grating compound lens unit is the extension direction of the optical axis of the grating compound lens unit.
  • Cross so that the display pixel set can be imaged by paraxial imaging, so the imaging quality of the lens layer to the display layer can be improved, and thus the focal length of the lens layer can be reduced and/or the image side field of view of the display device can be improved .

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Abstract

一种显示装置（100、200），包括显示层（110、210）和透镜层（120、220），透镜层（120、220）设置在显示层（110、210）的出光侧，且包括至少一个光栅复合透镜单元（121、221）；显示层（110、210）包括至少一个显示像素集（111、211），且显示像素集（111、211）配置为在显示过程中朝向光栅复合透镜单元（121、221）发射用于成像的光线；光栅复合透镜单元（121、221）配置为对显示像素集（111、211）进行光学成像；以及光栅复合透镜单元（121、221）还配置为偏转用于成像的光线，以使得光栅复合透镜单元（121、221）的像方中心视场方向与光栅复合透镜单元（121、221）的光轴的延伸方向交叉，以使得显示装置（100、200）具有一个或者多个视点。可以提升透镜层对显示层的成像质量。

Description

显示装置 技术领域
本公开的实施例涉及一种显示装置。
背景技术
随着显示技术的发展和生活水平的提高，消费者对显示装置提出了越来越高的要求。例如，消费者不仅期望显示装置能够显示高质量的显示画面，还希望显示装置能够具有较小的厚度和重量。
公开内容
本公开的至少一个实施例提供了一种显示装置，该显示装置包括显示层和透镜层，所述透镜层设置在所述显示层的出光侧，且包括至少一个光栅复合透镜单元；所述显示层包括至少一个显示像素集，且所述显示像素集配置为在显示过程中朝向所述光栅复合透镜单元发射用于成像的光线；所述光栅复合透镜单元配置为对所述显示像素集进行光学成像；以及所述光栅复合透镜单元还配置为偏转所述用于成像的光线，以使得所述光栅复合透镜单元的像方中心视场方向与所述光栅复合透镜单元的光轴的延伸方向交叉，以使得所述显示装置具有一个或者多个视点。
例如，在所述显示装置的至少一个示例中，所述光栅复合透镜单元包括透镜单元和光栅单元；所述透镜单元配置为对所述显示像素集进行光学成像；以及所述光栅单元配置为通过对所述用于成像的光线进行偏转以使得所述光栅复合透镜单元的像方中心视场方向与所述透镜单元的光轴的延伸方向交叉。
例如，在所述显示装置的至少一个示例中，所述透镜层还包括与所述光栅复合透镜单元并列设置的中心透镜；所述显示层还包括与所述显示像素集并列布置的中心显示像素集；所述中心显示像素集配置为在显示过程中朝向所述中心透镜发射用于成像的光线；所述中心透镜配置为使得所述中心显示像素集发射的用于成像的光线形成所述中心显示像素集的成像点；以及所述光栅单元配置为通过使得所述光栅复合透镜单元的像方中心视场方向与所述 透镜单元的光轴的延伸方向交叉以使得所述显示像素集的成像点与所述中心显示像素集的成像点拼接为所述显示装置的待显示图像的至少部分。
例如，在所述显示装置的至少一个示例中，所述透镜单元和所述光栅单元彼此贴合且叠置；以及相比于所述光栅单元，所述透镜单元更靠近所述显示层。
例如，在所述显示装置的至少一个示例中，所述透镜单元和所述光栅单元一体化形成为相位型透镜；以及所述相位型透镜配置在对所述显示像素集进行成像的同时将所述光栅复合透镜单元的像方中心视场方向偏离所述透镜单元的光轴。
例如，在所述显示装置的至少一个示例中，所述透镜单元的相位相对于所述光栅复合透镜单元的中心呈对称分布；以及所述光栅复合透镜单元的相位相对于所述光栅复合透镜单元的中心呈非对称分布。
例如，在所述显示装置的至少一个示例中，所述光栅单元包括多条光栅线条，所述多条光栅线条的取向方向彼此平行。
例如，在所述显示装置的至少一个示例中，所述光栅单元包括多个光栅子区；以及所述多个光栅子区配置为将入射至不同的所述光栅子区的光线朝向不同的方向偏转，以用于使得所述显示装置具有多个视点。
例如，在所述显示装置的至少一个示例中，所述多个视点排布方式为行排布、十字型排布、矩阵型排布或米字型排布。
例如，在所述显示装置的至少一个示例中，所述光栅复合透镜单元包括第一光栅复合透镜子区和第二光栅复合透镜子区；所述第一光栅复合透镜子区的像方中心视场方向与所述第一光栅复合透镜子区的透镜单元的光轴的夹角为第一角度，所述第二光栅复合透镜子区像方中心视场方向与所述第二光栅复合透镜子区的透镜单元的光轴的夹角为第二角度；所述第一角度不等于所述第二角度，以使得所述光栅复合透镜单元形成不同的视点。
例如，在所述显示装置的至少一个示例中，所述第一光栅复合透镜子区包括第一光栅子区，所述第二光栅复合透镜子区包括第二光栅子区；
所述第一光栅子区的光栅周期和所述第二光栅子区的光栅周期彼此不同，且所述第一光栅子区的光栅单元的光栅线条方向与所述第二光栅子区的光栅单元的光栅线条方向相同；或所述第一光栅子区的光栅单元的光栅线条方向和所述第二光栅子区的光栅单元的光栅线条方向彼此不同，且所述第一 光栅子区的光栅周期与所述第二光栅子区的光栅周期相同。
例如，在所述显示装置的至少一个示例中，所述第一光栅子区的光栅周期和所述第二光栅子区的光栅周期彼此不同；以及所述第一光栅子区的光栅单元的光栅线条方向和所述第二光栅子区的光栅单元的光栅线条方向彼此不同。
例如，在所述显示装置的至少一个示例中，所述透镜层包括多个光栅复合透镜单元；所述多个光栅复合透镜单元包括第一光栅复合透镜单元和第二光栅复合透镜单元；相比于所述第一光栅复合透镜单元，所述第二光栅复合透镜单元更为远离所述透镜层的中心；以及所述第二光栅复合透镜单元的光栅周期小于所述第一光栅复合透镜单元的光栅周期。
例如，在所述显示装置的至少一个示例中，所述第二光栅复合透镜单元的光栅单元的相位差值大于所述第一光栅复合透镜单元的光栅单元的相位差值；所述第二光栅复合透镜单元的光栅单元的相位差值为所述第二光栅复合透镜单元的光栅单元的最大相位与所述第二光栅复合透镜单元的光栅单元的最小相位之间的差值；以及所述第一光栅复合透镜单元的光栅单元的相位差值为所述第一光栅复合透镜单元的光栅单元的最大相位与所述第一光栅复合透镜单元的光栅单元的最小相位之间的差值。
例如，在所述显示装置的至少一个示例中，所述显示像素集包括至少一个显示像素；以及所述显示像素集在所述透镜层上正投影位于所述光栅复合透镜单元之内。
例如，在所述显示装置的至少一个示例中，所述光栅复合透镜单元的中心与所述透镜层的中心间隔设置；以及所述显示像素集在所述透镜层上正投影的中心与所述光栅复合透镜单元的中心实质上重合。
例如，在所述显示装置的至少一个示例中，所述显示层还包括围绕所述显示像素集设置且用于间隔相邻的所述显示像素集的间隔区域，所述间隔区域配置为非显示区域；以及所述显示像素集包括多个所述显示像素，所述间隔区域包括多个驱动元件，所述多个驱动元件用于驱动对应的所述显示像素集。
例如，在所述显示装置的至少一个示例中，所述的显示装置还包括间隔层。所述间隔层设置在所述显示层和所述透镜层之间；所述透镜单元的相位分布
Figure PCTCN2019083717-appb-000001
满足以下的表达式：
Figure PCTCN2019083717-appb-000002
其中，R为所述透镜层的中心在所述间隔层上的正投影到所述光栅复合透镜单元在所述间隔层上的正投影内的一位置的矢量，R n为所述透镜层的中心在所述间隔层上的正投影到所述光栅复合透镜单元的中心在所述间隔层上的正投影的矢量，f为所述光栅复合透镜单元的焦距，n为所述间隔层的折射率，λ为所述显示装置的有效工作波长。
例如，在所述显示装置的至少一个示例中，所述光栅单元的相位分布
Figure PCTCN2019083717-appb-000003
和光栅周期P1分别满足以下表达式：
Figure PCTCN2019083717-appb-000004
其中，θ为所述光栅复合透镜单元的像方中心视场方向的矢量r n与所述间隔层的法线方向的矢量t的夹角，r //为所述光栅复合透镜单元的像方中心视场方向的矢量r n在所述间隔层上的投影矢量。
例如，在所述显示装置的至少一个示例中，所述光栅复合透镜单元为二元光学透镜、基于超表面相位调控的透镜和基于全息材料的透镜的至少一种。
附图说明
为了更清楚地说明本公开的实施例的技术方案，下面将对实施例或相关技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅涉及本公开的一些实施例，并非对本公开的限制。
图1A是一种显示装置的截面示意图和光路图；
图1B是图1A示出的显示装置的平面示意图；
图1C是离轴成像的情况下透镜单元对显示像素集成像的仿真图；
图2是本公开的实施例提供的一种显示装置的剖面示意图；
图3A是图2示出的显示装置的示意性光路图；
图3B是图2示出的显示装置的中心透镜的示意性光路图；
图3C是图2示出的显示装置的光栅复合透镜单元的示意性光路图；
图4A是本公开的实施例提供的一种显示层的平面示意图；
图4B是本公开的实施例提供的一种显示像素集和间隔区域平面示意图；
图5A是本公开的实施例提供的一种透镜层的平面示意图；
图5B是图4A示出的显示层在图5A示出的透镜层上的正投影的示意图；
图6A是本公开的实施例提供的一种光栅单元的平面示意图；
图6B是本公开的实施例提供的一列光栅单元的平面示意图；
图7A是本公开的实施例提供的另一种透镜层的平面示意图；
图7B是本公开的实施例提供的显示装置提供的多个视点的多种排布形式；
图8是本公开的实施例提供的另一种显示装置的剖面示意图；
图9是图8示出的显示装置的示意性光路图；
图10A是图8中的光栅复合透镜单元的透镜单元的示意性相位分布图；
图10B是图8中的光栅复合透镜单元的光栅单元的示意性相位分布图；
图10C是图8中的光栅复合透镜单元的示意性相位分布图；
图10D是图8中的光栅复合透镜单元对入射其上的光线的会聚和偏转作用的示意图；
图10E是图8中的光栅复合透镜单元对显示像素集成像的仿真图；
图10F是光栅单元的相位差值对光线的偏转作用的影响的示意图；
图11A是用于示出显示装置结构参数的示意图；以及
图11B是光栅复合透镜单元在间隔层上的正投影的示意图。
具体实施方式
为使本公开实施例的目的、技术方案和优点更加清楚，下面将结合本公开实施例的附图，对本公开实施例的技术方案进行清楚、完整地描述。显然，所描述的实施例是本公开的一部分实施例，而不是全部的实施例。基于所描述的本公开的实施例，本领域普通技术人员在无需创造性劳动的前提下所获得的所有其他实施例，都属于本公开保护的范围。
除非另外定义，本公开使用的技术术语或者科学术语应当为本公开所属领域内具有一般技能的人士所理解的通常意义。本公开中使用的“第一”、“第二”以及类似的词语并不表示任何顺序、数量或者重要性，而只是用来区分不同的组成部分。同样，“一个”、“一”或者“该”等类似词语也不表示数量限制，而是表示存在至少一个。“包括”或者“包含”等类似的词语意指出现该词前面的元件或者物件涵盖出现在该词后面列举的元件或者物件及其等同，而不排除其他元件或者物件。“连接”或者“相连”等类似的词语并非限定于物理的或 者机械的连接，而是可以包括电性的连接，不管是直接的还是间接的。“上”、“下”、“左”、“右”等仅用于表示相对位置关系，当被描述对象的绝对位置改变后，则该相对位置关系也可能相应地改变。
图1A是一种显示装置500的截面示意图，图1B示出了图1A示出的显示装置500的平面示意图，该显示装置500例如可以应用在虚拟现实眼镜中。如图1A所示，该显示装置500包括显示层和透镜层520。显示层包括阵列排布的显示像素集510，并且显示像素集510包括至少一个显示像素511。透镜层520包括阵列排布的透镜单元521。
本申请的发明人在研究中注意到，在图1A和图1B示出的显示装置500中，多个透镜单元521中的部分个透镜单元在显示层上的正投影的中心与对应的显示像素集510的中心间隔设置，也即，显示像素集510(例如，显示像素集510的中心)与对应的透镜单元521的光轴530间隔设置。例如，如图1A和图1B所示，部分显示像素集510的至少部分区域设置在对应的透镜单元521在显示层上的正投影之外，以使得不同显示像素集510出射的光线均能传输至对应地视点(例如，第一视点VP1)处，进而使得不同显示像素集510的像点能够在显示装置500的像面550拼接为待显示图像。
然而，此种情况下，显示像素集510出射的光线与对应的透镜单元521的光轴530的夹角较大，此时，透镜单元521对显示像素集510的成像为离轴成像，由此像差较大且成像质量相对较差。图1C示出了离轴成像(10度±1.5度)的情况下，单个透镜单元521对显示像素集510成像的仿真结果图。此处，光线552表示主视角(10度)对应的光线，光线551表示对应于主视角(10度)-1.5度的光线，光线553表示对应于主视角(10度)+1.5度的光线。如图1C所示，在离轴成像的情况下，光线551、光线552和光线553在显示装置500的像面550形成的光斑的尺寸均较大，这表示在离轴成像(10度±1.5度)的情况下，透镜单元521对显示像素集510的成像质量已不满足实际应用需求。因此，无法通过设置更多的透镜单元521来增加显示装置500的像方视场角，由此图1A示出的显示装置500的总体视场角较小(例如，小于10°)。
本申请的发明人在研究中注意到，可以通过增加透镜单元521的焦距来提升图1A示出的显示装置500的成像质量。首先，当透镜单元521的焦距增加时，透镜单元521的曲率降低(曲率半径增加)，因此，透镜单元521 的厚度随位置变化的幅度减小，透镜单元521的相位随位置变化的幅度减小，由此透镜单元521的加工误差对成像质量的不利影响将减弱，对应地，透镜单元521的成像质量得到提升。其次，当透镜单元521的焦距增加时，在视场角固定的情况下，当透镜单元521的焦距增加时，透镜单元521与显示像素集510的距离增加，显示像素集510发射的且被透镜单元521接收的光线与透镜单元521的光轴的夹角的最大值降低，因此，透镜单元521对显示像素集510的成像的离轴程度降低(也即，更接近傍轴成像)，由此透镜单元521的成像质量得到提升。然而，本申请的发明人注意到，通过增加透镜单元521的焦距来提升显示装置500的成像质量的技术方案将增加显示装置500的厚度(例如，显示装置500的厚度大于1厘米)，这与消费者对显示装置500的要求相违背。此外，本申请的发明人在研究中还注意到，在图1A和图1B示出的显示装置中，不同的透镜单元521在显示层上的正投影的中心与对应的显示像素集510的中心的间距不同，这意味着显示像素集510在显示层中不均匀分布，由此增加了显示层的制作难度。
本公开的至少一个实施例提供了一种显示装置，该显示装置包括显示层和透镜层，透镜层设置在显示层的出光侧，且包括至少一个光栅复合透镜单元；显示层包括至少一个显示像素集，且显示像素集配置为在显示过程中朝向光栅复合透镜单元发射用于成像的光线；光栅复合透镜单元配置为对显示像素集进行光学成像；以及光栅复合透镜单元还配置为偏转用于成像的光线，以使得光栅复合透镜单元的像方中心视场方向与光栅复合透镜单元的光轴的延伸方向交叉，以使得显示装置具有一个或者多个视点。
在一些示例中，可以通过使用光栅复合透镜单元来对显示像素集进行成像以及通过偏转用于成像的光线使得光栅复合透镜单元的像方中心视场方向与光栅复合透镜单元的光轴的延伸方向交叉，由此可以采用傍轴成像的方式对显示像素集进行成像，因此可以提升透镜层对显示层的成像质量，并由此可以降低透镜层的焦距和/或提升显示装置的像方视场。
在一些示例中，透镜层包括阵列排布的多个光栅复合透镜单元，每个光栅复合透镜单元的像方中心视场方向与该光栅复合透镜单元的光轴的延伸方向交叉，由此使得每个光栅复合透镜单元的像方中心视场方向与光栅复合透镜单元阵列整体的成像光轴交叉。例如，光栅复合透镜单元阵列整体的成像光轴(也即，透镜层的成像光轴)是指通过人眼瞳孔中心的透镜层平面的法 线。例如，每个光栅复合透镜单元的像方中心视场方向与透镜层的成像光轴上的同一点相交，并因此形成显示装置的一个视点。例如，透镜层的成像光轴与透镜层垂直。
图2示出了本公开的实施例提供的一种显示装置100的截面示意图。图3A是图2示出的显示装置100的示意性光路图。该显示装置100例如可以应用在虚拟现实眼镜中。如图3A所示，显示装置100包括显示层110和透镜层120，且透镜层120设置在显示层110的出光侧。例如，显示层110和透镜层120在第三方向D3叠置。例如，透镜层的中心1200与显示层的中心1100在透镜层120上的正投影重合。例如，透镜层120可以包括多个透镜单元(例如，光栅复合透镜单元121)。图4A是本公开的实施例提供的一种显示层110的平面示意图。如图4A所示，显示层110包括中心显示像素集113以及围绕中心显示像素集113阵列排布的显示像素集111，在平行于第一方向D1和第二方向D2的平面内阵列排布；显示像素集111包括至少一个显示像素1111。例如，中心显示像素集113包括的显示像素的个数和排布方式例如可以与显示像素集111中的显示像素1111的个数和排布方式相同，在此不再赘述。例如，第一方向D1和第二方向D2彼此交叉(例如，垂直)，第三方向D3与第一方向D1交叉(例如，垂直)，以及第三方向D3与第二方向D2交叉(例如，垂直)。
需要说明的是，尽管图4A示例性的示出了每个显示像素集111包括九个显示像素，但本公开的实施例不限于此。根据实际应用需求，每个显示像素集111还可以包括一个显示像素、两个显示像素、十二个显示像素或者其它数量的显示像素。例如，通过使得显示像素集111包括多个显示像素，可以在透镜单元尺寸固定的情况下保证或提升显示装置的分辨率和显示效果，以及降低显示装置的制造难度(无需制造尺寸过小的透镜单元)。在显示像素集111包括多个显示像素时，多个显示像素的灰度可以独立控制。例如，每个显示像素集111包括的多个显示像素1111出射的光线的强度可以彼此不同，并可以用于形成显示装置100的待显示图像的图像子区或图像子画面。例如，基于每个显示像素集111形成的图像子区与基于其它的显示像素集111形成的图像子区在显示装置的像面150彼此结合可以形成一幅尺寸更大的图像。
如图4A所示，显示层110还包括围绕显示像素集111设置且用于间隔 相邻的显示像素集111的间隔区域112，间隔区域112配置为非显示区域。图4B示出了本公开的实施例提供的一种显示像素集111和间隔区域112平面示意图。如图4B所示，在一个示例中，间隔区域112包括多个驱动元件1112，每个驱动元件1112可以与对应的显示像素1111通过导线1113相连接，并用于驱动对应的显示像素集111。驱动元件1112例如可以包括薄膜晶体管。例如，通过将驱动元件1112设置在间隔区域112中，可以在显示像素集111中设置更多的显示像素1111，由此可以提升显示装置100的分辨率。在另一个示例中，显示像素1111包括驱动元件1112，也即，驱动元件1112设置在显示像素集111中。在再一个示例中，还可以使用普通的显示面板来作为本公开的实施例的显示层110，由此可以增加显示面板的选择范围；此种情况下，间隔区域112中的显示像素1111在显示过程中处于非工作状态。
图5A是本公开的实施例提供的一种透镜层120的平面示意图。例如，如图5A所示，透镜层120包括位于透镜层120中心的中心透镜124以及围绕中心透镜124阵列排布的光栅复合透镜单元121。例如，中心透镜124的中心与透镜层的中心1200重合，此种情况下，光栅复合透镜单元121的中心与透镜层的中心1200间隔设置。需要说明的是，尽管图5A示出了透镜层120包括多个光栅复合透镜单元121，但根据实际应用需求，透镜层120还可以仅包括一个光栅复合透镜单元121。在一些示例中，如图5A所示，中心透镜124和光栅复合透镜单元121在显示层110上的正投影均为正六边形；此种情况下，光栅复合透镜单元121围绕中心透镜124呈六角密排分布，由此可以提升显示层110的空间利用率。在另一些示例中，中心透镜124和光栅复合透镜单元121在显示层110上的正投影还可以为三角形(例如等边三角形)、矩形或其它适用的形状，在此不再赘述。
图5B示出了显示层110在透镜层120上的正投影的示意图。如图5B所示，多个显示像素集111与多个光栅复合透镜单元121一一对应，多个显示像素集111在透镜层120上正投影位于对应的光栅复合透镜单元121之内；中心显示像素集113在透镜层120上正投影位于中心透镜124之内。在一些示例中，如图5B所示，中心显示像素集113在透镜层120上正投影的中心与中心透镜124的中心实质上重合。在一些示例中，如图5B所示，多个显示像素集111在透镜层120上正投影的中心与对应的光栅复合透镜单元121的中心实质上重合。例如，多个显示像素集111在透镜层120上正投影的中 心与对应的光栅复合透镜单元121的中心可以完全重合。例如，在显示层110和透镜层120之间存在对准误差时，多个显示像素集111在透镜层120上正投影的中心与对应的光栅复合透镜单元121的中心之间还可以具有微小的间距(例如，小于显示像素集111尺寸的5％)，例如，该微小的间距可能会降低(略微降低)透镜层120对多个显示像素集111的成像质量，但透镜层120对多个显示像素集111的成像质量依然大于普通透镜层的成像质量。
下面结合图3A-图3C对图2示出的显示装置100的透镜层120对显示层110的成像原理进行示例性说明。图3B是图2示出的显示装置100的中心透镜124的示意性光路图；图3C是图2示出的显示装置100的光栅复合透镜单元121的示意性光路图。
如图3A和图3B所示，中心显示像素集113配置为在显示过程中朝向中心透镜124发射用于成像的光线。中心透镜124使得入射至中心透镜124之上的用于成像的光线的至少部分传输至位于显示装置100的出瞳平面上的第一视点V1，并由此使得中心显示像素集113发射的用于成像的光线在显示装置的像面150形成中心显示像素集113的成像点。如图3A和图3B所示，中心透镜的像方中心视场方向1242与中心透镜的光轴1241重合。例如，第一视点V1位于显示装置100的出瞳中，第一视点V1的直径例如约为0.8-1.5毫米；在一些示例中，第一视点V1形成了显示装置100的出瞳，在另一些示例中，显示装置100具有多视点，第一视点V1与其它视点共同形成了显示装置100的出瞳。需要说明的是，在本示例以及本公开的实施例的其它示例中，成像点可以为单个的图像像素点，也可以为由多个图像像素点组成的图像子区或图像子画面。
例如，如图3B所示，中心透镜124的像方中心视场方向1242是显示层110发出的、入射至中心透镜214的光心的光线离开中心透镜12后的传输方向。
如图3A和图3B所示，中心显示像素集113的中心、中心透镜124的中心可以均位于中心透镜的光轴1241上。例如，如图3A和图3B所示，第一视点V1也可以位于中心透镜的光轴1241上，由此可以提升用户观察到的图像的质量。
如图3A所示，光栅复合透镜单元121包括透镜单元122和光栅单元123，透镜单元122的焦距例如等于中心透镜124的焦距，透镜单元122的焦距和 中心透镜124的焦距例如均等于透镜层120和显示层110的间距。如图3C所示，显示像素集111配置为在显示过程中朝向光栅复合透镜单元121发射用于成像的光线。光栅复合透镜单元121还配置为偏转用于成像的光线，以使得光栅复合透镜单元121的像方中心视场方向1222与光栅复合透镜单元121的光轴(也即，透镜单元的光轴1221)的延伸方向交叉。需要说明的是，在本公开的实施例中，光栅复合透镜单元121的光轴是指光栅复合透镜单元121的透镜单元的光轴1221。
例如，如图3C所示，光栅复合透镜单元121的像方中心视场方向1222是显示层110发出的、入射至光栅复合透镜单元121的光心的光线离开光栅复合透镜单元121的后的传输方向。
如图3A和图3C所示，透镜单元122配置为对显示像素集111进行成像。例如，如图3C所示，在不设置光栅单元123的情况下，光栅复合透镜单元121的像方中心视场方向与透镜单元光轴1221重合。需要说明的是，不设置光栅单元123的情况下的光栅复合透镜单元121的像方中心视场方向等于透镜单元122的中心视场方向；透镜单元122的像方视场参见图3C的虚线围成的区域。如图3A和图3C所示，光栅单元123配置为通过对用于成像的光线进行偏转以使得光栅复合透镜单元121的像方中心视场方向1222偏离透镜单元122的光轴1221。
例如，光栅单元123配置为通过对将光栅复合透镜单元121的像方中心视场方向(以及对应的像方光路)从透镜单元122的光轴1221的延伸方向偏转到预定的视场方向，可以使得显示像素集111的成像点与中心显示像素集113的成像点拼接为显示装置100的待显示图像的至少部分。
例如，如图3A和图3C所示，光栅单元123配置为通过偏转光栅复合透镜单元121的像方中心视场方向1222使得显示像素集111出射的光线的至少部分传输至位于显示装置100出瞳平面上的第一视点V1上，由此使得光栅复合透镜单元121对显示像素集111的成像点与中心透镜124对中心显示像素集113可以拼接成待显示图像的至少部分(例如，在显示装置的像面150上拼接为一幅尺寸更大的图像)。
例如，如图3A所示，在显示层110包括多个显示像素集111且透镜层120包括多个光栅复合透镜单元121的情况下，多个光栅复合透镜单元121可以将对应的像方中心视场方向偏转预定的角度，以使得可以将多个光栅复 合透镜单元121对对应的显示像素集111的多个成像点与中心透镜124对中心显示像素集113的成像点拼接成待显示图像。例如，多个光栅复合透镜单元121的多个光栅单元123配置为通过偏转对应的光栅复合透镜单元121的像方中心视场方向1222使得多个显示像素集111出射的光线的至少部分均传输至位于显示装置100出瞳平面上的第一视点V1(例如，使得多个光栅复合透镜单元121的像方中心视场方向1222均穿过第一视点V1)，由此使得多个光栅复合透镜单元121对对应的显示像素集111的成像点与中心透镜124对中心显示像素集113的成像点可以拼接成待显示图像。例如，相邻的显示像素集111的像点彼此紧邻，由此可以形成一幅连续且不存在重叠的画面。在一些示例中，可以选用尺寸小的显示像素1111，对应地，可以选用具有较大放大倍率的透镜单元122，在此不再赘述。
在本公开的实施例提供的显示装置100的一些示例中，不仅中心透镜124对中心显示像素集113的成像为傍轴成像，光栅复合透镜单元121对显示像素集111的成像也为傍轴成像，由此提升了透镜层120的成像质量。因此，相比于图1A和图1B示出的显示装置100所采用的离轴成像的方案，光栅复合透镜单元121可以降低透镜层120的成像像差、提升透镜层120对显示像素集111的成像质量。此种情况下，在透镜层120焦距固定的情况下，光栅复合透镜单元121可以提升透镜层120的像方视场角(例如，将透镜层120的像方视场角提升至±60°以上)；在像方视场角固定的情况下，可以降低透镜层120的焦距(例如，透镜层120的焦距小于1毫米)，由此可以降低显示装置100的厚度，提升用户的使用体验。此外，相比于图1A和图1B示出的显示装置100，如图4A所示，显示像素1111可以在显示层110上均匀排布，因此不仅可以降低显示层110的设计和制作难度，还可以降低显示层110和透镜层120的对位难度。需要说明的是，透镜的傍轴成像是指用于成像的光线与该透镜的光轴的夹角θ较小，并满足下述的近似条件sinθ≈θ，以及cosθ≈1；例如θ≤±3°。在本公开的一些示例中，光栅复合透镜单元121对显示像素集111的成像为傍轴成像是指光栅复合透镜单元121的物方视场中的光线与透镜光轴的夹角较小。
如图3A所示，透镜单元122和光栅单元123可以彼此贴合且叠置在显示层110的出光侧。在一些示例中，如图3A所示，相比于光栅单元123，透镜单元122更靠近显示层110，此种情况下，光栅单元123将不会影响光栅 复合透镜单元121的物方视场，由此可以进一步的提升光栅复合透镜单元121的成像质量。
图6A是本公开的实施例提供的一种光栅单元123的平面示意图。如图6A所示，光栅单元123包括多条光栅线条1231，且多条光栅线条1231的取向方向(也即，延伸方向)彼此平行，光栅单元123的光栅线条1231与第二方向D2的夹角(锐角)为该光栅单元123的取向角；相邻的光栅线条123之间的间距(在垂直于光栅线条1231的延伸方向上的间距)为光栅单元123的光栅周期。
例如，透镜层120的至少一个光栅复合透镜单元121包括第一光栅复合透镜单元和第二光栅复合透镜单元；相比于第一光栅复合透镜单元，第二光栅复合透镜单元更为远离透镜层的中心1200；第二光栅复合透镜单元的光栅周期小于第一光栅复合透镜单元的光栅周期，以使得第二光栅复合透镜单元的中心视场方向与第二光栅复合透镜单元的透镜单元的光轴的夹角大于第一光栅复合透镜单元的像方中心视场方向与第一光栅复合透镜单元的透镜单元的光轴的夹角，由此使得第二光栅复合透镜单元对应的显示像素集111出射的光线的至少部分以及第一光栅复合透镜单元对应的显示像素集111出射的光线的至少部分均能够传输至位于显示装置100出瞳平面上的第一视点V1。
下面结合图6B进行示例性说明。图6B是本公开的实施例提供的一列光栅单元123的平面示意图，如图6B所示，对于沿第二方向D2排列的多个光栅复合透镜单元，相比于第一光栅复合透镜单元，第二光栅复合透镜单元更为远离透镜层的中心1200；并且第二光栅复合透镜单元包括的光栅单元1252的光栅周期小于第一光栅复合透镜单元包括的光栅单元1251的光栅周期。由于根据光栅方程可知，光栅周期越小，衍射角越大。因此，第二光栅复合透镜单元包括的光栅单元1252对光线的偏转角度大于第一光栅复合透镜单元包括的光栅单元1251对光线的偏转角度，进而第二光栅复合透镜单元的像方中心视场方向与第二光栅复合透镜单元的透镜单元的光轴的夹角，大于第一光栅复合透镜单元的像方中心视场方向与第一光栅复合透镜单元的透镜单元的光轴的夹角；此种情况下，第二光栅复合透镜单元对应的显示像素集111出射的光线的至少部分以及第一光栅复合透镜单元对应的显示像素集111出射的光线的至少部分，均能够传输至位于显示装置100出瞳平面上的第一视点V1，并且第一光栅复合透镜单元对显示像素集111的成像点以及第二光栅 复合透镜单元对显示像素集111的成像点，与中心透镜124对中心显示像素集113的成像点可以拼接成待显示图像的至少部分(例如，在显示装置的像面150上可以拼接成待显示图像的至少部分)。
例如，在沿透镜层120的中心朝向透镜层120的边缘的方向上，可以逐步降低光栅复合透镜单元121的光栅单元123的光栅周期，以使得在沿透镜层120的中心朝向透镜层120的边缘的方向上，光栅复合透镜单元121的像方中心视场方向偏转角度逐渐增加，进而可以将多个光栅复合透镜单元121对对应的显示像素集111的成像点与中心透镜124对中心显示像素集113拼接成待显示图像(例如，一幅连续且不存在重叠的画面)。例如，在一些示例中，光栅复合透镜单元121可以通过对显示像素集111成像形成多个视点，下面结合图7A和图7B进行示例性说明。
图7A示出了光栅复合透镜单元121的多个光栅复合透镜单元子区，图7B示出了光栅复合透镜单元121形成的多个视点。例如，如图7A所示，光栅复合透镜单元121可以包括多个光栅复合透镜单元子区(子区1、子区2、……、子区n)，且多个光栅复合透镜单元子区配置为基于入射至光栅复合透镜单元121上的光线形成多个视点(视点1、视点2、……、视点n)。例如，多个光栅复合透镜单元子区可配置为形成图7B示出的n个视点，n个视点对应的图像可以为相同的图像，也即，不同视点对应的图像具有相同的颜色和灰度分布。此种情况下，当用户的眼睛在移动过程中，用户也可以持续观看到显示装置100显示的图像，也即，图7A示出的光栅复合透镜单元121可以增大显示装置100的观察区域(eye box)或观察窗口，并因此可以提升用户的使用体验。
例如，光栅复合透镜单元子区的形状、多个光栅复合透镜单元子区在光栅复合透镜单元121中的排布方式以及多个视点的排布形式可以根据实际应用需求进行设定，本公开的实施例对此不做具体限定。
例如，如图7A所示，在光栅复合透镜单元121为六边形的情况下，光栅复合透镜单元子区可以为三角形，且三角形的一个顶点与光栅复合透镜单元121的中心重合。例如，光栅复合透镜单元121可以包括六个、十二个、十八个、或者其它适用数目的光栅复合透镜单元子区，在此不再赘述。需要说明的是，在光栅复合透镜单元121的形状为其它形状的情况下，可以参照图7A来设置光栅复合透镜单元子区，在此不再赘述。
例如，如图7B所示，光栅复合透镜单元121形成的n个视点的排布方式可以为行排布(也即，n个视点排布成一行)、十字型排布(也即，n个视点排布成彼此垂直的一行和一列)、矩阵型排布、米字型排布、或其它适用的排布方式，在此不再赘述。在一些示例中，相邻的视点之间的间距小于瞳孔直径，由此可以在使得相邻的视点(不同视点)分别加载对应的光场图像的情况下实现光场显示；在另一些示例中，相邻的视点之间的间距还可以大于瞳孔直径，由此可以在使得相邻的视点(不同视点)分别加载相同的图像的情况下实现人眼观察视窗(观察区域)的扩展。此外，在前述的光场显示情况下，也可以具有人眼观察视窗的扩展效果。
例如，下面以光栅复合透镜单元121包括第一光栅复合透镜单元子区和第二光栅复合透镜单元子区为例对光栅复合透镜单元121形成的多个视点的原理进行示例性说明。
例如，光栅单元123包括第一光栅子区和第二光栅子区，透镜单元122包括对应于第一光栅子区的第一透镜子区和对应于第二光栅子区的第二透镜子区，第一光栅子区和第一透镜子区彼此结合以形成第一光栅复合透镜单元子区，第二光栅子区和第二透镜子区彼此结合以形成第二光栅复合透镜单元子区。显示像素集111发射的用于成像的光线包括入射至第一透镜子区和第一光栅子区上的第一光线以及入射至第二透镜子区和第二光栅子区上的第二光线；第一透镜子区配置为基于第一光线对显示像素集111成像，第二透镜子区配置为基于第二光线对显示像素集111成像；第一光栅子区配置为将光栅复合透镜单元121的对应于第一光栅子区的区域(也即，第一光栅复合透镜子区)的像方中心视场方向偏离第一光栅复合透镜子区的透镜单元的光轴第一角度，第二光栅子区配置为将光栅复合透镜单元121的对应于第二光栅子区的区域(也即，第二光栅复合透镜子区)的像方中心视场方向偏离第二光栅复合透镜子区的透镜单元的光轴第二角度，该示例中第一角度不等于第二角度，由此可以基于光栅复合透镜单元121形成不同的视点。
例如，可以通过调节第一光栅子区的光栅周期、第二光栅子区的光栅周期、第一光栅子区的光栅单元123的光栅线条1231方向和第二光栅子区的光栅单元123的光栅线条1231方向中的至少一个来使得光栅复合透镜单元121的对应于第一光栅子区的区域的像方中心视场方向以及光栅复合透镜单元121的对应于第二光栅子区的区域的像方中心视场方向偏转不同的角度。
例如，第一光栅子区的光栅周期和第二光栅子区的光栅周期彼此不同，且第一光栅子区的光栅单元123的光栅线条1231方向与第二光栅子区的光栅单元123的光栅线条1231方向相同。又例如，第一光栅子区的光栅单元123的光栅线条1231方向和第二光栅子区的光栅单元123的光栅线条1231方向彼此不同，且第一光栅子区的光栅周期与第二光栅子区的光栅周期相同。再例如，第一光栅子区的光栅周期和第二光栅子区的光栅周期彼此不同，并且，第一光栅子区的光栅单元123的光栅线条1231方向和第二光栅子区的光栅单元123的光栅线条1231方向彼此不同。
下面对显示层110的实现方式以及彩色化显示进行示例性的描述。
例如，显示层110的可以实现为自发光显示面板(例如，有机发光显示面板)、液晶显示面板或其它适用的显示面板。例如，显示层110可以用于输出单色图像。又例如，显示层110可还可以用于输出彩色图像。例如，可以使用下述两种方法中的任一种实现彩色图像的显示。
在第一种方法中，显示层110可以包括用于发射具有第一颜色的光线的第一显示像素，用于发射具有第二颜色的光线的第二显示像素以及用于发射具有第三颜色的光线的第三显示像素，第一颜色、第二颜色和第三颜色例如为红色、绿色和蓝色。
例如，第一显示像素、第二显示像素和第三显示像素可以对应于同一个光栅复合透镜单元121，该光栅复合透镜单元121包括依次叠置的透镜单元122、第一光栅子层、第二光栅子层以及第三光栅子层，例如，第一光栅子层、第二光栅子层以及第三光栅子层在显示层110上的正投影完全重合；第一光栅子层、第二光栅子层以及第三光栅子层的工作波长分别对应于第一颜色、第二颜色和第三颜色，由此该光栅复合透镜单元121可以使得不同颜色的光线具有相同的偏转角度，由此可以抑制或消除色散(不同颜色光线的出射角度不同)导致的重影问题。例如，第一光栅子层、第二光栅子层以及第三光栅子层对于波长为非工作波长的光线不具有偏转作用。例如，第一光栅子层对于波长为第二颜色和第三颜色的光线不具有偏转作用。
又例如，第一显示像素、第二显示像素和第三显示像素还可以分别对应于三个不同的光栅复合透镜单元121，由此第一显示像素、第二显示像素和第三显示像素输出的光线可以直接通过不同的光栅复合透镜单元121分别成像，第一显示像素、第二显示像素和第三显示像素输出的光线(多个第一显 示像素、第二显示像素和第三显示像素)可在虚像面上叠加成一幅完整的彩色画面而不会产生重影或串扰。
在第二种方法中，显示层110包括时序背光源和光强调制层，时序背光源具有三种颜色的光源(例如发光二极管(LED))，可以在一帧图像的显示周期内顺次向光强调制层输出第一颜色的光线、第二颜色的光线和第三颜色的光线，光强调制层对第一颜色的光线、第二颜色的光线和第三颜色的光线分别进行调制形成第一颜色的中间画面、第二颜色的中间画面和第三颜色的中间画面，用户的眼睛通过合成第一颜色的中间画面、第二颜色的中间画面和第三颜色的中间画面可以感受到彩色画面。例如，在此种方法中，也可以采用适用的方法(例如，由叠置的透镜单元、第一光栅子层、第二光栅子层以及第三光栅子层形成的光栅复合透镜单元)来抑制或消除光栅复合透镜单元的色散导致的重影问题，在此不再赘述。
需要说明的是，本公开的实施例提供的显示装置的光栅复合透镜单元不限于包括分立设置的光栅单元和透镜单元。根据实际应用需求，本公开的实施例提供的显示装置的光栅复合透镜单元还可以包括一体化设置的光栅单元和透镜单元。下面结合图8和图9进行示例性说明。
图8示出了本公开的实施例提供的另一种显示装置200的剖面示意图。图9是图8示出的显示装置200的示意性光路图。该显示装置200例如可以应用在虚拟现实眼镜中。如图8所示，该显示装置200包括显示层210和透镜层220。例如，透镜层220的中心可以与显示层210的中心在透镜层220上的正投影重合。
如图8所示，显示层210包括中心显示像素集213以及围绕中心显示像素集213阵列排布的显示像素集211，显示像素集211包括至少一个显示像素，中心显示像素集213的设置方式类似于显示像素集211的设置方式。例如，显示像素层的具体设置方式可以参见图2示出的示例，在此不再赘述。
如图8所示，透镜层220包括中心透镜224以及围绕中心透镜224阵列布置的多个光栅复合透镜221。需要说明的是，尽管图8示出了透镜层220包括多个光栅复合透镜221，但本公开的实施例不限于此，例如，在一些示例中，透镜层220还可以仅包括一个光栅复合透镜221，在此不再赘述。例如，中心透镜224的中心可以与透镜层220的中心重合，此种情况下，光栅复合透镜单元221的中心与透镜层220的中心间隔设置。
如图8所示，多个显示像素集211与多个光栅复合透镜单元221一一对应，多个显示像素集211在透镜层220上正投影位于对应的光栅复合透镜单元221之内；中心显示像素集213在透镜层220上正投影位于中心透镜224之内。在一些示例中，中心显示像素集213在透镜层220上正投影的中心与中心透镜224的中心实质上重合，多个显示像素集211显示像素集211在透镜层220上正投影的中心与对应的光栅复合透镜单元221的中心实质上重合。
如图8和图9所示，中心显示像素集213配置为在显示过程中朝向光中心透镜224发射用于成像的光线。中心透镜224使得入射至中心透镜224之上的用于成像的光线的至少部分传输至位于显示装置200出瞳平面上的第一视点V1，并由此使得中心显示像素集213发射的用于成像的光线在显示装置200的像面形成中心显示像素集213的成像点。如图8和图9所示，中心透镜224的像方中心视场方向2242与中心透镜的光轴2241重合。
如图8和图9所示，中心显示像素集213的中心、中心透镜224的中心可以均位于中心透镜的光轴2241上。例如，如图8和图9所示，第一视点V1也可以位于中心透镜的光轴2241上，此种情况下，用户可以看到更为对称的图像，由此可以提升用户观察到的图像的质量。
如图9所示，显示像素集211配置为在显示过程中朝向光栅复合透镜单元221发射用于成像的光线。光栅复合透镜单元221包括透镜单元和光栅单元，如图8和图9所示，透镜单元和光栅单元一体化形成为相位型透镜，且该相位型透镜配置在对显示像素集211进行成像的同时对用于成像的光线进行偏转以使得光栅复合透镜单元221的像方中心视场方向2212与光栅复合透镜221的光轴的延伸方向交叉(例如，使得光栅复合透镜单元221的像方中心视场方向2212穿过第一视点V1)，并由此使得显示像素集211的成像点与中心显示像素集213的成像点可以拼接为显示装置200的待显示图像的至少部分。
例如，所述相位型透镜配置在对所述显示像素集出射的光线进行成像的同时将所述光栅复合透镜单元的像方中心视场方向偏离所述透镜单元的光轴。
下面结合图10A-图10E对透镜单元、光栅单元以及光栅复合透镜单元221进行说明。
图10A示例性的示出了图9中的光栅复合透镜单元221包括的透镜单元 的相位分布(z轴表示透镜单元的相位)。如图10A所示，透镜单元的相位相对于光栅复合透镜221的中心(x＝0，y＝0)呈对称分布，且透镜单元配置为对显示像素集211实现成像的功能(例如，对入射其上的光线进行会聚或准直)。
图10B示例性的示出了图9中的光栅复合透镜单元221包括的光栅单元的相位分布(z轴表示光栅单元的相位)。如图10B所示，光栅单元的相位相对于光栅复合透镜221的中心(x＝0，y＝0)呈非对称分布，光栅单元的相位例如满足线性变化的规律。如图10B所示，光栅单元可以对入射其上的光线进行偏转。
图10C示例性的示出了图9中的光栅复合透镜单元221的相位分布(z轴表示光栅复合透镜单元的相位)，图10D示例性的示出了图9中的光栅复合透镜单元221的光路图。如图10C所示，光栅复合透镜单元221的相位相对于光栅复合透镜221的中心(x＝0，y＝0)呈非对称分布。如图10D所示，光栅复合透镜单元221可以在对入射其上的发散光线进行准直(或会聚)的同时对光线进行偏转，由此使得光栅复合透镜单元221的像方中心视场方向2212与光栅复合透镜221的光轴的延伸方向交叉。
图10E示例性的示出了图9中的光栅复合透镜单元221对显示像素集211成像的仿真图(使用ZEMAX仿真软件)。光线252表示对应于主视角的光线，光线251表示对应于主视角(10度)-3度的光线，光线253表示对应于主视角(10度)+3度的光线。如图10E所示，对应于相同视角的光线在像面的光斑尺寸很小。如图10E所示，光线251、光线252和光线253在像面形成的光斑的尺寸均较小，这表明本公开的实施例提供的显示装置200的光栅复合透镜单元221可以使得某一较大视角中心附近范围(例如，±3°视角)内的成像具有傍轴成像的成像质量。例如，本公开的实施例提供的显示装置200的光栅复合透镜单元221可以将图1A示出的显示装置200中的离轴成像转换为傍轴成像，由此可以提升显示装置200的成像质量。
图10F示出了光栅单元的相位差值对光线的偏转作用的影响，此处光栅单元的相位差值是指光栅单元的最大相位与最小相位的差值。如图10F所示，在光栅单元的相位差值
Figure PCTCN2019083717-appb-000005
增加时，光栅单元对光线的偏转角度θ dt越大。这是由于光线的偏转角度θ dt越大，因光线偏转导致的光线传输路径相位差
Figure PCTCN2019083717-appb-000006
越大，由此传输路径相位差
Figure PCTCN2019083717-appb-000007
可以弥补光栅单元的相位差值
Figure PCTCN2019083717-appb-000008
例如，在光栅单元的相位差值
Figure PCTCN2019083717-appb-000009
越大时，光栅复合透镜单元221的相位差值越大时，该光栅复合透镜单元221对对应的显示像素集211的出射光线的偏转角度可以越大。例如，在沿透镜层220的中心朝向透镜层220的边缘的方向上，可以逐步增加光栅复合透镜单元221的光栅单元的相位差值(或者光栅复合透镜单元221的光栅单元的相位差值)，以使得在沿透镜层220中心朝向透镜层220边缘的方向上，光栅复合透镜单元221的像方中心视场方向的偏转角度逐渐增加，进而可以将多个光栅复合透镜单元221对对应的显示像素集211的成像点与中心透镜224对中心显示像素集213拼接成待显示图像(例如，一幅连续且不存在重叠的画面)。下面结合图9进行示例性地说明。
例如，如图9所示，在显示层210包括多个显示像素集211且透镜层220包括多个光栅复合透镜单元221的情况下，多个光栅复合透镜单元221可以将对应的像方中心视场方向偏转预定的角度，例如，使得每个光栅复合透镜单元221的像方中心视场方向2212均穿过第一视点V1。如图9所示，不同光栅复合透镜单元221的像方中心视场方向2212具有不同的预定偏转角度，光栅复合透镜单元221的中心与透镜层220的中心的距离越远，光栅复合透镜单元221的像方中心视场方向2212具有的预定偏转角度越大，由此可以使得多个光栅复合透镜单元221的视场彼此拼接为一个更大的视场(例如，大于60度)，并且使得多个显示像素集211的成像点与中心透镜224对中心显示像素集213可以拼接成待显示图像。例如，相邻的显示像素集211的成像点彼此紧邻，以形成一幅连续且不存在重叠的画面。
例如，可以通过设置光栅复合透镜单元221的相位差值来控制对应的显示像素集211的成像点的偏转角度，此处，光栅复合透镜单元221的相位差值是指该光栅复合透镜单元221的最大相位与该光栅复合透镜单元221的最小相位之间的差值。例如，在光栅复合透镜单元221的相位差值越大时，该光栅复合透镜单元221的像方中心视场方向2212与该光栅复合透镜单元221的透镜单元的光轴的夹角越大(也即，该光栅复合透镜单元221的像方中心视场方向2212的偏转角度越大)。例如，在沿透镜层220中心朝向透镜层220边缘的方向上，可以逐步增加光栅复合透镜单元221的相位差值，由此可以使得在沿透镜层220中心朝向透镜层220边缘的方向上，光栅复合透镜单元221的像方中心视场方向2212与该光栅复合透镜单元221的透镜单元的光轴 的夹角逐步增加(即，该光栅复合透镜单元221的像方中心视场方向2212的偏转角度逐渐增加)，进而可以将多个光栅复合透镜单元221对对应的显示像素集211的成像点与中心透镜224对中心显示像素集213可以拼接成待显示图像(例如，一幅连续且不存在重叠的画面)。
在本公开的实施例提供的显示装置200的一些示例中，不仅中心透镜224对中心显示像素集213的成像为傍轴成像，光栅复合透镜单元221对显示像素集211的成像也为傍轴成像，由此提升了透镜层的成像质量。因此，相比于图1A和图1B示出的显示装置200所采用的离轴成像的方案，光栅复合透镜单元221可以降低透镜层220的成像像差、提升透镜层220对显示像素集211的成像质量。此种情况下，在透镜层220焦距固定的情况下，光栅复合透镜单元221可以提升透镜层220的像方视场角(例如，将透镜层220的像方视场提升至±60°以上)；在像方视场角固定的情况下，可以降低透镜层220焦距(例如，小于1毫米)，由此可以降低显示装置200的厚度，提升用户的使用体验。此外，相比于图1A和图1B示出的显示装置200，显示像素可以在显示层210上均匀排布，因此不仅可以降低显示层210的设计和制作难度，还可以降低显示层210和透镜层220的对位难度。
如图8所示，显示装置200还包括设置在显示层210和透镜层220之间的间隔层。例如，该间隔层可以为间隔基板；又例如，该间隔层还可以为空气层，此时，透镜层220与显示层210采用框贴的方式彼此叠合。
下面结合图11A和图11B对透镜单元和光栅单元的具体设置方式进行示例性说明。如图11B所示，光栅复合透镜单元221在间隔层上的正投影为六边形，但本公开的实施例不限于此，根据实际应用需求，光栅复合透镜单元221在间隔层上的正投影还可以为三角形或者其它适用的形状。
例如，透镜单元的相位分布
Figure PCTCN2019083717-appb-000010
光栅单元的相位分布
Figure PCTCN2019083717-appb-000011
光栅周期P1以及光栅复合透镜单元221的相位分布
Figure PCTCN2019083717-appb-000012
可以分别满足以下表达式：
Figure PCTCN2019083717-appb-000013
Figure PCTCN2019083717-appb-000014
Figure PCTCN2019083717-appb-000015
Figure PCTCN2019083717-appb-000016
此处，R为透镜层220的中心在间隔层上的正投影到光栅复合透镜单元221在间隔层上的正投影内的一位置的矢量，R n为透镜层220的中心在间隔层上的正投影到光栅复合透镜单元221的中心在间隔层上的正投影的矢量，f为光栅复合透镜单元221的焦距，n为间隔层的折射率，λ为显示装置200的有效工作波长；θ为光栅复合透镜单元221的像方中心视场方向2212的矢量r n与间隔层的法线方向的矢量t的夹角，r //为光栅复合透镜单元221的像方中心视场方向2212的矢量r n在间隔层上的投影矢量。
例如，透镜单元的相位分布
Figure PCTCN2019083717-appb-000017
可用于实现光栅复合透镜单元221对平面波的进行无球差汇聚或准直。例如，透镜单元的相位分布
Figure PCTCN2019083717-appb-000018
用于弥补入射至透镜单元的不同位置上的不同光线因传输路径不同而导致的光程差异，由此使得由显示层210发射的且入射至透镜单元不同位置上的不同光线历经相同的光程。
例如，光栅单元的相位分布
Figure PCTCN2019083717-appb-000019
用于将入射其上的光线进行偏转，由此使得光栅复合透镜单元221可以在对入射其上的光线准直的同时对光线进行偏转，并因此使得光栅复合透镜单元221的像方中心视场方向2212与光栅复合透镜221的光轴的延伸方向交叉。由此在每个光栅复合透镜单元221对对应的显示像素集211的成像满足傍轴成像的情况下，光栅复合透镜单元221可以通过将像方光路偏转至预定视场，将不同显示像素集211的成像点与中心显示像素集213的成像点拼接形成待显示图像(在显示装置的像面250上拼接)。此种情况下，不仅可以提升透镜层220的成像质量，还可以增加显示装置200的像方视场和/或降低显示装置200的尺寸。
例如，在一些实施例中，除了可以在光栅复合透镜单元221中引入光栅单元的相位，根据实际应用需求，还可以在光栅复合透镜单元221中像差矫正位相，由此可以进一步提升光栅复合透镜单元221的成像质量。例如，像差矫正位相可以使用泽尼克多项式(Zernike多项式)进行表示。例如，可以基于希望矫正的像差类型选择适用的泽尼克多项式，并将对应于该泽尼克多项式的位相引入光栅复合透镜单元221。泽尼克多项式与像差之间的关系可以参见相关技术，在此不再赘述。
如图8和图9所示，透镜单元和光栅单元可以一体化形成为相位型光栅复合透镜单元221，相比于透镜单元和光栅单元分立设置型光栅复合透镜单 元221，一体化形成的相位型光栅复合透镜单元221可以更好的控制光线的会聚角度(入射至光栅复合透镜单元221的光线的发散角与从光栅复合透镜单元221出射的光线的发散角的差值)和偏转角度，由此可以进一步地提升成像效果。例如，可以在制作相位型光栅复合透镜单元221的材料中同时引入透镜单元的相位和光栅单元的相位，由此使得透镜单元和光栅单元可以一体化形成为相位型光栅复合透镜单元221。
例如，光栅复合透镜单元221可以实现为平面型透镜。需要说明的是，本公开的实施例中的平面型透镜是指透镜无需借助普通几何透镜的曲面面型即可实现成像功能的透镜。例如，基于平面型透镜的光栅复合透镜单元221例如不会像普通几何透镜那样受限于透镜面型、材料折射率等因素，进而可以提升光栅复合透镜单元221的设计灵活性。又例如，平面型透镜可以实现无像差(例如，无球差)的成像，由此可以基于平面型透镜的光栅复合透镜单元221可以进一步地提升透镜层220的成像质量。在一些示例中，平面型透镜的表面可以具有尺寸较小阶梯结构，但不具有曲面面型，例如，平面型透镜可以为二元光学透镜。在另一些示例中，平面型透镜的表面可以为平面，例如，平面型透镜可以为基于超表面相位调控的透镜或基于全息材料的透镜。
例如，在光栅复合透镜单元221实现为二元光学透镜的情况下，例如可以采用多台阶结构的套刻(也即，多次刻蚀)或压印工艺(相位级数例如为N，在采用套刻工艺情况下，工艺次数例如为log2 N)，透镜层220的厚度例如为5-10微米(典型的位相调制单元的尺寸位于微米量级)。例如，由于二元光学透镜通常对偏振不敏感，因此可对自然光进行调制。例如，由于二元光学透镜色散相对较大，因此可以选择发光光谱较窄显示面板作为显示层210。例如，可以选择OLED(有机发光二级管)显示面板、微LED(微型发光二级管)显示面板、量子点LCD(液晶显示面板)。
例如，在光栅复合透镜单元221实现为基于超表面相位调控的透镜(例如，超透镜，Metalens)的情况下，可以基于半导体制作工艺(例如，单次光刻工艺和单次压印中的至少一个)制作透镜层220。例如，光栅复合透镜单元221可以包括并列布置的位相调制单元，且位相调制单元的宽度W、长度L、高度H以及间距P例如可以满足W＝95nm，L＝250nm，H＝600nm，P＝325nm。例如，透镜层220可以呈平板状。例如，基于超表面相位调控的光栅复合透镜单元221具有下述特点：栅复合透镜单元的位相调制精度高(例如，由于 位相调制单元的尺度为亚波长量级)，因此可以进一步地降低光栅复合透镜单元221的像差；栅复合透镜单元厚度小(光栅复合透镜单元221的厚度为亚波长量级)，由此可以进一步地降低显示装置200的厚度；基于偏振实现位相调控，因此可以选用能够输出圆偏振光或线偏振光显示面板作为显示层210；色散可控性较好(相比常规的二元光学衍射器件)，因此对显示层210输出光线的光谱宽度的要求较低。例如，此种情况下，显示层210可以选用OLED、微LED、量子点LCD等显示面板，并包括用于对显示面板输出的光线进行偏振调制处理的器件。
在光栅复合透镜单元221实现为基于全息材料的透镜的情况下，光栅复合透镜单元221例如具有以下特点。首先，光栅复合透镜单元221的位相调制精度高(理论上可以接近连续调制)，因此可以进一步地降低光栅复合透镜单元221的像差。其次，光栅复合透镜单元221厚度较小，由此可以较好的降低显示装置200的厚度。例如，光栅复合透镜单元221的厚度约为2-20微米，在光栅复合透镜单元221的厚度为2-3微米的情况下，对应的折射率调制度较高(例如，0.2)。再次，可以通过形成布拉格体光栅结构来实现光栅复合透镜单元221，由此可以提升光栅复合透镜单元221效率(例如，衍射效率)；此时，可以采用预定的曝光光源预先形成所需的相位分布。此外，光栅复合透镜单元221存在色散，因此，显示层210可以选用OLED、微LED、量子点LCD等显示面板。在选用偏振敏感型材料制作光栅复合透镜单元221的情况下，显示层210还包括用于对显示面板输出的光线进行偏振调制处理的器件。
下面结合图11A对显示装置200的设置参数进行示例性的说明。如图11A所示，显示装置200的出瞳距离d例如约为10-14毫米(例如，12毫米)。例如，光栅复合透镜单元221的直径D可以基于光栅复合透镜单元221的衍射角以及人眼的角分辨之下(例如，2’)进行设定，光栅复合透镜单元221的直径例如为1-2毫米(例如，大于1.15毫米)。需要说明的是，在光栅复合透镜单元221在显示层210上的正投影不是圆形的情况下，光栅复合透镜单元221的直径D是指能够围绕光栅复合透镜单元221在显示层210上的正投影的圆形的最小直径。例如，光栅复合透镜单元221的焦距约等于光栅复合透镜单元221的直径D，因此，光栅复合透镜单元221的F数(f/D)以及显示装置200的厚度约等于1。
光栅复合透镜单元221的物距l o、像距l img以及焦距满足以下表达式：
Figure PCTCN2019083717-appb-000020
光栅复合透镜单元221的像距l img例如为1-6米(例如，2米)，对应地，光栅复合透镜单元221的物距l o约等于透镜的焦距f。光栅复合透镜单元221的焦距f等于显示层210与透镜层220之间的间距。
需要说明的是，以上描述是以显示层包括位于显示层的中心显示像素集以及围绕中心显示像素集阵列排布的显示像素集，且透镜层包括位于透镜层中心的中心透镜以及围绕透镜层的中心透镜阵列排布的光栅复合透镜单元为例对本公开的实施例进行示例性的说明，但本公开的实施例不限于此。
例如，根据实际应用需求，显示层可以不设置中心显示像素集，且透镜层不设置中心透镜(例如，透镜层仅包括光栅复合透镜单元且任意两个相邻的光栅复合透镜单元彼此相接)；此种情况下，光栅复合透镜单元中的光栅单元配置为偏转用于成像的光线，以使得不同的光栅复合透镜单元的像方中心视场方向例如可以穿过同一点(例如，穿过第一视点V1)，因此，不同的显示像素集的像点可以拼接成待显示图像，由此，可以采用傍轴成像的方式对例如每个显示像素集进行成像。
在一个示例中，透镜层还可以包括对应于中心透镜的光栅单元，对应于中心透镜的光栅单元与透镜层例如叠置；此种情况下，入射至中心透镜的光线在离开中心透镜之后将入射至对应于中心透镜的光栅单元上，对应于中心透镜的光栅单元使得上述离开中心透镜入射至对应于中心透镜的光栅单元光线偏转。在另一个示例中，透镜层还可以不包括对应于中心透镜的光栅单元，此种情况下，入射至中心透镜的光线在离开中心透镜之后将例如直接传输至显示装置的视点所在位置处。
例如，透镜层的中心配置为显示装置的光学中心，在进行设计和制作显示装置时，可以以透镜层的中心作为基准。例如，显示装置的视点在透镜层上的正投影可以与透镜层的中心重合。例如，透镜层的中心可以是透镜层的物理结构的中心，以尽可能的提升显示装置的显示图像的质量；又例如，透镜层的中心还可以不是透镜层的物理结构的中心。例如，在透镜层包括中心透镜的情况下，透镜层中心的与中心透镜的中心彼此重合。
需要说明的是，为清楚起见(例如，清楚的示出不同光栅复合透镜单元之间的拼接)，图3A-图3C以及图9中仅示出了离开光栅复合透镜单元的部 分光线，因此，看起来光栅复合透镜单元使得入射其上的光线转变为会聚光束，然而，显示装置在工作时，光栅复合透镜单元被配置为对相应的显示像素集成虚像的，因此，从光栅复合透镜单元出射的入射至显示装置的视点(入射至用户眼睛)的光线并非为会聚光线。需要说明的是，在光栅复合透镜单元与显示像素集之间，仅仅示出了位于显示像素集的中心的显示像素发射的光线(也即，仅仅示出了入射到光栅复合透镜单元的部分光线)，入射到光栅复合透镜单元的其他部分光线没有示出；在光栅复合透镜单元远离显示层的一侧(例如，靠近人眼侧)，为了展示不同光栅复合透镜单元的相对人眼的视场拼接作用(也即，为了展示在光栅复合透镜单元对像方视场的偏转作用下，不同光栅复合透镜单元的像方视场可以拼接成一个更大的视场)，图3A-图3C以及图9中示出了显示像素集包括的显示像素的整体发射的光线通过对应光栅复合透镜单元到达人眼的光线的角度范围(也即，从光栅复合透镜单元出射的光线中入射到人眼的光线的角度范围)，所以图3A-图3C以及图9给人将光线汇聚到人眼的错觉(也即，入射到人眼的光线并非是会聚光线)。例如，从光栅复合透镜单元出射的光线的发散角小于显示像素集发出的入射至光栅复合透镜单元的光线的发散角，因此，显示装置的像面位于显示层的发光面的远离透镜层的一侧(例如，显示层的远离透镜层的一侧)。例如，从光栅复合透镜单元出射的光线的发散角可以接近于零，此种情况下，显示装置的像面(虚像的像面)可以位于无穷远处。例如，光栅复合透镜单元具有会聚作用。需要说明的是，光栅复合透镜单元具有会聚作用是指光栅复合透镜单元可以使得从光栅复合透镜单元出射的光线的发散角小于显示像素集发出的入射至光栅复合透镜单元的光线的发散角，而不是指光栅复合透镜单元具有使得从光栅复合透镜单元出射的光线为会聚光线。例如，光栅复合透镜单元对入射其上的光线的会聚和偏转作用的示例可以参见图10D。
在本公开的一些示例中，显示装置的视点可以是用于人眼观察的虚拟窗口(观察区域)的中心，在用户的眼睛位于显示装置的视点处，用户可以观察到显示装置显示的图像。
例如，光栅复合透镜单元配置为对显示像素集进行合适的傍轴或离轴光学成像，以扩大透镜层的整体的成像视场的角度，由此可以提升用户的使用体验。
例如，光栅复合透镜单元的像方中心视场方向是显示像素集发出的、入 射至光栅复合透镜单元的光心的光线离开光栅复合透镜单元后的传输方向。又例如，对于特定的一个光栅复合透镜单元和显示像素集的组合结构而言，光栅复合透镜单元的像方中心视场方向是显示装置的视点(也即，人眼前相应视点)和光栅复合透镜单元的光心之间的连线的延伸方向。再例如，光栅复合透镜单元的像方中心视场方向是显示装置的视点与光栅复合透镜单元的光心之间的连线对应的虚像平面上某一像素点相对显示装置的视点(也即，人眼前相应视点)的方向。
例如，光栅复合透镜的光轴为光栅复合透镜单元的透镜单元的光轴。
本公开的实施例提供了一种显示装置。在一些示例中，可以通过使用光栅复合透镜单元来对显示像素集进行成像以及通过偏转用于成像的光线使得光栅复合透镜单元的像方中心视场方向与光栅复合透镜单元的光轴的延伸方向交叉，由此可以采用傍轴成像的方式对显示像素集进行成像，因此可以提升透镜层对显示层的成像质量，并由此可以降低透镜层的焦距和/或提升显示装置的像方视场。
虽然上文中已经用一般性说明及具体实施方式，对本公开作了详尽的描述，但在本公开的实施例基础上，可以对之作一些修改或改进，这对本领域技术人员而言是显而易见的。因此，在不偏离本公开精神的基础上所做的这些修改或改进，均属于本公开要求保护的范围。
以上所述仅是本公开的示范性实施方式，而非用于限制本公开的保护范围，本公开的保护范围由所附的权利要求确定。

Claims (20)

  1. 一种显示装置，包括显示层和透镜层，
    其中，所述透镜层设置在所述显示层的出光侧，且包括至少一个光栅复合透镜单元；
    所述显示层包括至少一个显示像素集，且所述显示像素集配置为在显示过程中朝向所述光栅复合透镜单元发射用于成像的光线；
    所述光栅复合透镜单元配置为对所述显示像素集进行光学成像；以及
    所述光栅复合透镜单元还配置为偏转所述用于成像的光线，以使得所述光栅复合透镜单元的像方中心视场方向与所述光栅复合透镜单元的光轴的延伸方向交叉，以使得所述显示装置具有一个或者多个视点。
  2. 根据权利要求1所述的显示装置，其中，所述光栅复合透镜单元包括透镜单元和光栅单元；
    所述透镜单元配置为对所述显示像素集进行光学成像；以及
    所述光栅单元配置为通过对所述用于成像的光线进行偏转以使得所述光栅复合透镜单元的像方中心视场方向与所述透镜单元的光轴的延伸方向交叉。
  3. 根据权利要求2所述的显示装置，其中，所述透镜层还包括与所述光栅复合透镜单元并列设置的中心透镜；
    所述显示层还包括与所述显示像素集并列布置的中心显示像素集；
    所述中心显示像素集配置为在显示过程中朝向所述中心透镜发射用于成像的光线；
    所述中心透镜配置为使得所述中心显示像素集发射的用于成像的光线形成所述中心显示像素集的成像点；以及
    所述光栅单元配置为通过使得所述光栅复合透镜单元的像方中心视场方向与所述透镜单元的光轴的延伸方向交叉以使得所述显示像素集的成像点与所述中心显示像素集的成像点拼接为所述显示装置的待显示图像的至少部分。
  4. 根据权利要求2或3所述的显示装置，其中，所述透镜单元和所述光栅单元彼此贴合且叠置；以及
    相比于所述光栅单元，所述透镜单元更靠近所述显示层。
  5. 根据权利要求2或3所述的显示装置，其中，所述透镜单元和所述光栅单元一体化形成为相位型透镜；以及
    所述相位型透镜配置在对所述显示像素集进行成像的同时将所述光栅复合透镜单元的像方中心视场方向偏离所述透镜单元的光轴。
  6. 根据权利要求5所述的显示装置，其中，所述透镜单元的相位相对于所述光栅复合透镜单元的中心呈对称分布；以及
    所述光栅复合透镜单元的相位相对于所述光栅复合透镜单元的中心呈非对称分布。
  7. 根据权利要求2-6任一所述的显示装置，其中，所述光栅单元包括多条光栅线条，所述多条光栅线条的取向方向彼此平行。
  8. 根据权利要求2-6任一所述的显示装置，其中，所述光栅单元包括多个光栅子区；以及
    所述多个光栅子区配置为将入射至不同的所述光栅子区的光线朝向不同的方向偏转，以用于使得所述显示装置具有多个视点。
  9. 根据权利要求8所述的显示装置，其中，所述多个视点排布方式为行排布、十字型排布、矩阵型排布或米字型排布。
  10. 根据权利要求8任一所述的显示装置，其中，所述光栅复合透镜单元包括第一光栅复合透镜子区和第二光栅复合透镜子区；
    所述第一光栅复合透镜子区的像方中心视场方向与所述第一光栅复合透镜子区的透镜单元的光轴的夹角为第一角度，所述第二光栅复合透镜子区像方中心视场方向与所述第二光栅复合透镜子区的透镜单元的光轴的夹角为第二角度；
    所述第一角度不等于所述第二角度，以使得所述光栅复合透镜单元形成不同的视点。
  11. 根据权利要求10所述的显示装置，其中，所述第一光栅复合透镜子区包括第一光栅子区，所述第二光栅复合透镜子区包括第二光栅子区；
    所述第一光栅子区的光栅周期和所述第二光栅子区的光栅周期彼此不同，且所述第一光栅子区的光栅单元的光栅线条方向与所述第二光栅子区的光栅单元的光栅线条方向相同；或
    所述第一光栅子区的光栅单元的光栅线条方向和所述第二光栅子区的光栅单元的光栅线条方向彼此不同，且所述第一光栅子区的光栅周期与所述第 二光栅子区的光栅周期相同。
  12. 根据权利要求10所述的显示装置，其中，所述第一光栅子区的光栅周期和所述第二光栅子区的光栅周期彼此不同；以及
    所述第一光栅子区的光栅单元的光栅线条方向和所述第二光栅子区的光栅单元的光栅线条方向彼此不同。
  13. 根据权利要求1-12任一所述的显示装置，其中，
    所述透镜层包括多个光栅复合透镜单元；
    所述多个光栅复合透镜单元包括第一光栅复合透镜单元和第二光栅复合透镜单元；
    相比于所述第一光栅复合透镜单元，所述第二光栅复合透镜单元更为远离所述透镜层的中心；以及
    所述第二光栅复合透镜单元的光栅周期小于所述第一光栅复合透镜单元的光栅周期。
  14. 根据权利要求13所述的显示装置，其中，所述第二光栅复合透镜单元的光栅单元的相位差值大于所述第一光栅复合透镜单元的光栅单元的相位差值；
    所述第二光栅复合透镜单元的光栅单元的相位差值为所述第二光栅复合透镜单元的光栅单元的最大相位与所述第二光栅复合透镜单元的光栅单元的最小相位之间的差值；以及
    所述第一光栅复合透镜单元的光栅单元的相位差值为所述第一光栅复合透镜单元的光栅单元的最大相位与所述第一光栅复合透镜单元的光栅单元的最小相位之间的差值。
  15. 根据权利要求1-14任一所述的显示装置，其中，所述显示像素集包括至少一个显示像素；以及
    所述显示像素集在所述透镜层上正投影位于所述光栅复合透镜单元之内。
  16. 根据权利要求15所述的显示装置，其中，所述光栅复合透镜单元的中心与所述透镜层的中心间隔设置；以及
    所述显示像素集在所述透镜层上正投影的中心与所述光栅复合透镜单元的中心实质上重合。
  17. 根据权利要求16所述的显示装置，其中，所述显示层还包括围绕所 述显示像素集设置且用于间隔相邻的所述显示像素集的间隔区域，所述间隔区域配置为非显示区域；以及
    所述显示像素集包括多个所述显示像素，所述间隔区域包括多个驱动元件，所述多个驱动元件用于驱动对应的所述显示像素集。
  18. 根据权利要求2-17任一所述的显示装置，还包括间隔层，其中，
    所述间隔层设置在所述显示层和所述透镜层之间；
    所述透镜单元的相位分布
    Figure PCTCN2019083717-appb-100001
    满足以下的表达式：
    Figure PCTCN2019083717-appb-100002
    其中，R为所述透镜层的中心在所述间隔层上的正投影到所述光栅复合透镜单元在所述间隔层上的正投影内的一位置的矢量，
    R n为所述透镜层的中心在所述间隔层上的正投影到所述光栅复合透镜单元的中心在所述间隔层上的正投影的矢量，
    f为所述光栅复合透镜单元的焦距，
    n为所述间隔层的折射率，
    λ为所述显示装置的有效工作波长。
  19. 根据权利要求2-17任一所述的显示装置，其中，所述光栅单元的相位分布
    Figure PCTCN2019083717-appb-100003
    和光栅周期P1分别满足以下表达式：
    Figure PCTCN2019083717-appb-100004
    Figure PCTCN2019083717-appb-100005
    其中，θ为所述光栅复合透镜单元的像方中心视场方向的矢量r n与所述间隔层的法线方向的矢量t的夹角，
    r //为所述光栅复合透镜单元的像方中心视场方向的矢量r n在所述间隔层上的投影矢量。
  20. 根据权利要求5或6所述的显示装置，其中，所述光栅复合透镜单元为二元光学透镜、基于超表面相位调控的透镜和基于全息材料的透镜的至少一种。
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