Double-entrance-pupil waveguide display device

Abstract

The utility model discloses a double-entrance pupil waveguide display device, which comprises an optical waveguide unit, the optical waveguide unit comprises an optical waveguide plate, the optical waveguide plate comprises a first main plane and a second main plane, and the first main plane is provided with a first entrance pupil grating element, a second entrance pupil grating element and a first exit pupil grating element; the second main plane is provided with a first pupil expanding grating element, a second pupil expanding grating element and a second exit pupil grating element; the first exit pupil grating element and the second exit pupil grating element form an exit pupil unit; the first entrance pupil grating element and the second entrance pupil grating element are rotationally symmetrical about the center of the exit pupil unit; the first light engine corresponds to the first entrance pupil unit and is used for providing first image light; and the second light engine corresponds to the second entrance pupil unit and is used for providing second image light. According to the utility model, a waveguide structure with double light engines and double entrance pupils is adopted, so that the brightness uniformity and color uniformity of an output image of the display device can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of display devices, and in particular to a dual-entry-pupil waveguide display device. Background Art

[0002] Diffraction optical waveguides use the diffraction effect of light to modulate the light beam using a grating structure. In conventional single-layer, single-optical, single-entrance pupil waveguide display devices, due to the different step lengths and diffraction efficiencies of total internal reflection of light of different colors in the waveguide, the intensity distribution of the output light of different color images is different, which in turn leads to poor color uniformity of the superimposed image. Specifically, the optical waveguide AR display device is mainly composed of a light engine and a flat waveguide that integrates a coupling input element and a coupling output element. The light emitted from the light engine enters the waveguide plate after the diffraction effect of the coupling input element to form a coupled input light. The coupled input light propagates to the coupling output element area in the waveguide plate in the form of total reflection and is coupled out multiple times to form an expansion of the light beam. Here, according to the waveguide display principle, the light coupled into the waveguide is coupled out multiple times at the output grating to achieve exit pupil expansion, allowing the observer to see the projected image in a larger spatial range. However, multiple diffractions in the waveguide will also cause the intensity of the light remaining in the waveguide to gradually decay, causing the intensity of the coupled output light to gradually weaken in the waveguide propagation direction. The problem that arises is that the brightness of the image observed by the human eye at different exit pupil positions is different, which affects the display effect, such as Figure 1 Especially for waveguide display devices with a large field of view and a large exit pupil, this phenomenon will be more serious due to the greater number of total reflections.

[0003] In order to solve the above problem, a common method to achieve uniform brightness display is to gradually improve the efficiency of output coupling to compensate for the weakening of the light intensity propagating in the waveguide. However, due to the different propagation angles of incident light in the waveguide at different viewing angles, the total reflection angle and the number of total reflections are also different, such as Figure 2 As shown in part a of the figure, in addition, the light of different wavelengths at the same field of view also has different propagation angles in the waveguide, as shown in part a of the figure. Figure 2 Therefore, this method cannot optimize the uniformity of the exit pupil brightness of all fields of view.

[0004] In addition, the prior art CN115494573A proposes a diffraction light waveguide and display device with high color uniformity. Although a turning zone is provided between the coupling-in zone and the outcoupling zone on the waveguide plate to improve the uniformity of the image light output from the outcoupling zone, only one coupling-in zone is used in the scheme. Therefore, in the outcoupling zone, there are still light outputs with different intensities at different positions near and far from the coupling-in zone, resulting in a mediocre final uniformity effect. Utility Model Content

[0005] An embodiment of the present invention provides a dual-entry-pupil waveguide display device, which aims to improve the brightness uniformity and color uniformity of an output image of the display device.

[0006] The present invention provides a dual-entrance-pupil waveguide display device, comprising a light waveguide unit, wherein the light waveguide unit comprises a light waveguide plate, wherein the light waveguide plate comprises a first main plane and a second main plane, wherein the first main plane is provided with a first entrance-pupil grating element, a second entrance-pupil grating element, and a first exit-pupil grating element; and the second main plane is provided with a first pupil expansion grating element, a second pupil expansion grating element, and a second exit-pupil grating element.

[0007] The first entrance pupil grating element constitutes a first entrance pupil unit, and the second entrance pupil grating element constitutes a second entrance pupil unit; the first exit pupil grating element and the second exit pupil grating element have at least a partial overlap in their projections in the thickness direction of the optical waveguide plate, and the two together constitute the exit pupil unit; the first entrance pupil grating element and the second entrance pupil grating element are rotationally symmetric about the center of the exit pupil unit;

[0008] The dual-entry-pupil waveguide display device further includes a first light engine corresponding to the first entrance pupil unit, for providing a first image light; wherein the first entrance pupil grating element couples the first image light to form a first guided light transmitted to the first pupil expansion grating element;

[0009] The dual-entry-pupil waveguide display device further includes a second light engine corresponding to the second entrance pupil unit, for providing a second image light; wherein the second entrance pupil grating element couples the second image light to form a second guided light transmitted to the second pupil expansion grating element;

[0010] The first pupil expansion grating element receives the first transmitted light and forms a first turned transmitted light transmitted to the exit pupil unit. The second pupil expansion grating element receives the second transmitted light and forms a second turned transmitted light transmitted to the exit pupil unit. The first turned transmitted light and the second turned transmitted light are coupled out by the exit pupil unit to form output image light.

[0011] Furthermore, the grating periods of all grating elements arranged on the first principal plane are the same, and the grating periods of all grating elements arranged on the second principal plane are the same.

[0012] Furthermore, the grating period of all grating elements arranged on the first principal plane is the same as the grating period of all grating elements arranged on the second principal plane.

[0013] Furthermore, the images displayed by the first light engine and the second light engine are identical or symmetrical or rotationally symmetrical to each other.

[0014] Furthermore, the first exit pupil grating element and the second exit pupil grating element are projected and overlapped in the thickness direction of the optical waveguide plate.

[0015] Furthermore, the first pupil expansion grating element and the second pupil expansion grating element are rotationally symmetric about the center of the exit pupil unit.

[0016] Furthermore, the first turning transmission light formed by the first pupil expansion grating element and transmitted to the exit pupil unit and the second turning transmission light formed by the second pupil expansion grating element and transmitted to the exit pupil unit propagate in opposite directions in the exit pupil unit area.

[0017] Furthermore, the first light engine and the second light engine are located on the same side or different sides of the optical waveguide plate.

[0018] Furthermore, the first pupil expansion grating element constitutes a first pupil expansion unit, and the second pupil expansion grating element constitutes a second pupil expansion unit;

[0019] The first pupil expansion unit and the second pupil expansion unit are respectively located on the upper and lower sides or the left and right sides of the exit pupil unit.

[0020] Furthermore, when the first pupil expansion unit and the second pupil expansion unit are respectively located on the upper and lower sides of the exit pupil unit, the grating vector directions of the first entrance pupil grating element and the second entrance pupil grating element are arranged horizontally;

[0021] When the first pupil expansion unit and the second pupil expansion unit are respectively located on the left and right sides of the exit pupil unit, the grating vector directions of the first entrance pupil grating element and the second entrance pupil grating element are arranged vertically;

[0022] The included angle between the grating vector directions of the first exit pupil grating element and the second exit pupil grating element is 50° to 70°.

[0023] An embodiment of the present invention provides a dual-entry pupil waveguide display device. The display device adopts a rotationally symmetrically distributed dual light engine and a dual-entry pupil waveguide architecture, which can make the image output light intensity distribution of different wavelengths more uniform and the light intensity distribution of each color more consistent, thereby achieving the effect of improving the brightness uniformity and color uniformity of the output image. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 Schematic diagram of waveguide propagation in the prior art;

[0026] Figure 2 is another waveguide propagation schematic diagram in the prior art;

[0027] Figure 3 A schematic diagram of waveguide propagation of a dual-entry-pupil waveguide display device provided by an embodiment of the present utility model;

[0028] Figure 4 A schematic structural diagram of a dual-entry-pupil waveguide display device provided by an embodiment of the present utility model;

[0029] Figure 5 Another structural schematic diagram of a dual-entry-pupil waveguide display device provided by an embodiment of the present utility model;

[0030] Figure 6 A schematic diagram of light beam propagation of a dual-entry-pupil waveguide display device provided by an embodiment of the present utility model;

[0031] Figure 7 Another schematic diagram of light beam propagation of a dual-entry-pupil waveguide display device provided by an embodiment of the present utility model;

[0032] Figure 8 This is one of the schematic diagrams of grating distribution of a dual-entry-pupil waveguide display device provided by an embodiment of the present utility model;

[0033] Figure 9 The second schematic diagram of grating distribution of a dual-entry-pupil waveguide display device provided by an embodiment of the present utility model;

[0034] Figure 10 The third schematic diagram of grating distribution of a dual-entry-pupil waveguide display device provided by an embodiment of the present invention;

[0035] Figure 11 A fourth schematic diagram of grating distribution of a dual-entry-pupil waveguide display device provided by an embodiment of the present invention;

[0036] Figure 12 One of the wave vector diagrams of a dual-entry-pupil waveguide display device provided by an embodiment of the present utility model;

[0037] Figure 13 The second wave vector diagram of a dual-entry-pupil waveguide display device provided by an embodiment of the present invention;

[0038] Figure 14 The third wave vector diagram of a dual-entry-pupil waveguide display device provided by an embodiment of the present invention;

[0039] Figure 15This is a fourth wave vector diagram of a dual-entry pupil waveguide display device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0041] It will be understood that when used in this specification and the appended claims, the terms “comprises” and “comprising” indicate the presence of described features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0042] It should also be understood that the terms used in this utility model specification are only for the purpose of describing specific embodiments and are not intended to limit the utility model. As used in this utility model specification and the appended claims, the singular forms "a", "an" and "the" are intended to include plural forms unless the context clearly indicates otherwise.

[0043] It should be further understood that the term “and / or” used in the present specification and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0044] See below Figures 3 to 5 The present invention provides a dual-entry pupil waveguide display device, comprising a light waveguide unit, wherein the light waveguide unit comprises a light waveguide plate SUB1, wherein the light waveguide plate SUB1 comprises a first main plane and a second main plane, Figure 6 and Figure 7 The first principal plane is provided with a first entrance pupil grating element (i.e. Figure 6 DOE11 or Figure 7 DOE13 in. As can be seen from the subsequent content, this embodiment provides two solutions, so two sets of numbers are used. When no drawings are indicated, the numbers are not added for the time being), the second entrance pupil grating element (i.e. Figure 6 DOE12 or Figure 7 DOE14 in the ) and the first exit pupil grating element (ie Figure 6 DOE301 or Figure 7 The second principal plane is provided with a first pupil expansion grating element (ie Figure 6DOE21 or Figure 7 DOE23 in), the second pupil expansion grating element (ie Figure 6 DOE22 or Figure 7 DOE24 in) and the second exit pupil grating element (ie Figure 6 DOE311 or Figure 7 DOE313 in

[0045] The first entrance pupil grating element constitutes a first entrance pupil unit (i.e. Figure 4 Number 11 or Figure 5 The second entrance pupil grating element constitutes a second entrance pupil unit (ie Figure 4 Number 12 or Figure 5 The first exit pupil grating element and the second exit pupil grating element are projected at least partially overlapped in the thickness direction of the optical waveguide plate SUB1, and the two together constitute an exit pupil unit (ie Figure 4 Number 31 or Figure 5 The first entrance pupil grating element and the second entrance pupil grating element are rotationally symmetric about the center of the exit pupil unit;

[0046] The dual-entry-pupil waveguide display device further includes a first light engine 41 corresponding to the first entrance pupil unit, for providing a first image light; wherein the first entrance pupil grating element couples the input first image light to form a first guided light transmitted to the first pupil expansion grating element;

[0047] The dual-entry-pupil waveguide display device further includes a second light engine 42 corresponding to the second entrance pupil unit, for providing a second image light; wherein the second entrance pupil grating element couples the second image light to form a second guided light transmitted to the second pupil expansion grating element;

[0048] The first pupil expansion grating element receives the first transmitted light and forms a first turned transmitted light transmitted to the exit pupil unit. The second pupil expansion grating element receives the second transmitted light and forms a second turned transmitted light transmitted to the exit pupil unit. The first turned transmitted light and the second turned transmitted light are coupled out by the exit pupil unit to form output image light.

[0049] The dual-entry-pupil waveguide display device described in this embodiment includes a light waveguide unit. Specifically, the light waveguide unit includes a light waveguide plate SUB1 having a first principal plane and a second principal plane, a first entrance pupil grating element, a second entrance pupil grating element, and a first exit pupil grating element disposed on the first principal plane of the light waveguide plate SUB1, and a first pupil expansion grating element, a second pupil expansion grating element, and a second exit pupil grating element disposed on the second principal plane of the light waveguide plate SUB1. The first entrance pupil grating element and the second entrance pupil grating element respectively constitute the first entrance pupil unit and the second entrance pupil unit, the first pupil expansion grating element and the second pupil expansion grating element respectively constitute the first pupil expansion unit and the second pupil expansion unit, and the first exit pupil grating element and the second entrance pupil grating element constitute the exit pupil unit. Furthermore, the dual-entry-pupil waveguide display device also includes a first light engine 41 and a second light engine 42. Among them, the first light engine 41 can provide the first image light for the first entrance pupil unit, and the first image light is coupled by the first entrance pupil grating element to form the first transmission light, and the first transmission light is coupled by the first pupil expansion grating element to form the first turning transmission light. At the same time, the second light engine 42 can provide the second image light for the second entrance pupil unit, and the second image light is coupled by the second entrance pupil grating element to form the second transmission light, and the second transmission light is coupled by the second pupil expansion grating element to form the second turning transmission light. Finally, the first turning transmission light and the second turning transmission light will be coupled and output by the exit pupil unit to form the output image light.

[0050] This embodiment is based on a waveguide architecture with dual light engines and dual entrance pupils with a rotationally symmetrical distribution. This can make the intensity distribution of image output light of different wavelengths more uniform and the intensity distribution of each color more consistent, thereby achieving the effect of improving the brightness uniformity and color uniformity of the output image.

[0051] In practical application scenarios, the dual-entry-pupil waveguide display device provided in this embodiment has the following principle: Figure 3 As shown, after the light emitted by the two light engines enters the optical waveguide module, it can be transmitted in opposite directions in the exit pupil unit 31, thereby achieving complementary intensity of the coupled output light, thereby solving the problem of uneven brightness and color distribution of the light emitted from the exit pupil unit 31. Here, the first light engine 41 and the second light engine 42 can be located on the same side of the optical waveguide plate SUB1 or on opposite sides of the optical waveguide plate SUB1. Furthermore, the first image displayed by the first light engine 41 and the second image displayed by the second light engine 42 can be identical, symmetrical, or rotationally symmetrical. It should also be noted that the dual-entry-pupil waveguide display device provided in this embodiment is particularly suitable for large-format optical waveguide display systems.

[0052] In a specific embodiment, the first pupil expansion grating element and the second pupil expansion grating element are rotationally symmetric about the center of the exit pupil unit.

[0053] That is to say, this embodiment can further improve the uniformity of the intensity distribution of image output light of different wavelengths and the consistency of the intensity distribution of each color light by adopting a rotationally symmetrically distributed dual light engine and a dual-entry pupil waveguide architecture, thereby achieving the effect of improving the brightness uniformity and color uniformity of the output image.

[0054] In one embodiment, the grating periods of all grating elements arranged on the first principal plane are the same, and the grating periods of all grating elements arranged on the second principal plane are the same.

[0055] Furthermore, the grating period of all grating elements arranged on the first principal plane is the same as the grating period of all grating elements arranged on the second principal plane.

[0056] Furthermore, the first exit pupil grating element and the second exit pupil grating element are projected and overlapped in the thickness direction of the optical waveguide plate.

[0057] This embodiment uses a double-sided printed optical waveguide plate SUB1, i.e., diffraction gratings are provided on both sides of the optical waveguide plate SUB1. The grating period (d) and grating direction (θ) of the diffraction grating can be determined by the grating vector V of the diffraction grating. The grating vector V can be defined as a vector having a direction perpendicular to the diffraction lines of the diffraction grating and an amplitude given by 2π / d, where d is the grating period (i.e., the fringe spacing).

[0058] In a specific embodiment, the projections of the first exit pupil grating element and the second exit pupil grating element in the thickness direction of the optical waveguide plate SUB1 at least partially overlap.

[0059] The grating period of the first entrance pupil grating element, the second entrance pupil grating element and the first exit pupil grating element is the same, the grating period of the first expanded pupil grating element, the second expanded pupil grating element and the second exit pupil grating element is the same, and the grating period of all grating elements arranged on the first principal plane is the same as the grating period of all grating elements arranged on the second principal plane.

[0060] In one embodiment, the first pupil expansion grating element constitutes a first pupil expansion unit, and the second pupil expansion grating element constitutes a second pupil expansion unit;

[0061] The first pupil expansion unit and the second pupil expansion unit are respectively located on the upper and lower sides or the left and right sides of the exit pupil unit.

[0062] This embodiment provides two architectural solutions based on the positions of the first pupil expansion unit and the second pupil expansion unit. Specifically:

[0063] Option 1: Combination Figure 4The exit pupil unit 31 is located at the center of the optical waveguide plate SUB1; the first pupil expansion unit 21 and the second pupil expansion unit 22 are respectively located above and below the exit pupil unit 31; the first entrance pupil unit 11 is located on the left side of the first pupil expansion unit 21, and the second entrance pupil unit 12 is located on the right side of the second pupil expansion unit 22. The positions of the first entrance pupil unit 11 and the second entrance pupil unit 12 are rotationally symmetrical about the geometric center of the exit pupil unit 31.

[0064] Option 2: Combination Figure 5 The exit pupil unit 32 is located at the center of the optical waveguide plate SUB1; the first pupil expansion unit 23 and the second pupil expansion unit 24 are respectively located on the left and right sides of the exit pupil unit 32; the first entrance pupil unit 13 is located above the first pupil expansion unit 23, and the second entrance pupil unit 14 is located below the second pupil expansion unit 24. The positions of the first entrance pupil unit 13 and the second entrance pupil unit 14 are rotationally symmetrical about the geometric center of the exit pupil unit 32.

[0065] Based on Figure 4 and Figure 5 In the display device shown in FIG. 1 , this embodiment enables the exit pupil unit 31 and the exit pupil unit 32 to receive the light coupled into the optical waveguide plate SUB1 by the entrance pupil unit in two directions.

[0066] Here, as Figure 4 As shown, when the first pupil expansion unit 21 and the second pupil expansion unit 22 are respectively located on the upper and lower sides of the exit pupil unit 31, the grating vector directions of the first entrance pupil grating element DOE11 and the second entrance pupil grating element DOE12 are arranged horizontally;

[0067] like Figure 5 As shown, when the first pupil expansion unit 23 and the second pupil expansion unit 24 are respectively located on the left and right sides of the exit pupil unit 32, the grating vector directions of the first entrance pupil grating element DOE13 and the second entrance pupil grating element DOE14 are arranged vertically;

[0068] In addition, whether Figure 4 The corresponding plan or Figure 5 In the corresponding solution, the angles between the grating vector directions of the first exit pupil grating element and the second exit pupil grating element are both 50° to 70°.

[0069] Combine Figure 8 and Figure 9 ,in, Figure 8 is the specific form of the grating distribution on the first principal plane of the optical waveguide plate SUB1 in scheme 1, Figure 9This is the specific form of the grating distribution on the second principal plane of the optical waveguide plate SUB1 in Scheme 1. Specifically, the first principal plane is provided with a diffraction grating DOE11 (i.e., the first entrance pupil grating element), DOE12 (i.e., the second entrance pupil grating element), and DOE301 (i.e., the first exit pupil grating element). In the diffraction grating DOE11, there is a grating vector V11 pointing in the positive direction of the x-axis, with a direction θ11 and a period d11; in the diffraction grating DOE12, there is a grating vector V12 pointing in the negative direction of the x-axis, with a direction θ12 and a period d12; in the diffraction grating DOE301, there is a grating vector V301 pointing in the positive direction of the x-axis, with a direction θ301 and a period d301; and there may also be a grating vector V302 pointing in the negative direction of the x-axis, with a direction θ302 and a period d301.

[0070] On the second principal plane are diffraction grating DOE21 (i.e., the first pupil expansion grating element), DOE22 (i.e., the second pupil expansion grating element), and DOE311 (i.e., the second exit pupil grating element). Diffraction grating DOE21 has a grating vector V21 with a direction θ21 and a period d21; diffraction grating DOE22 has a grating vector V22 with a direction θ22 and a period d22; diffraction grating DOE311 has a grating vector V311 with a direction θ311 and a period d311, and may also have a grating vector V312 with a direction θ312 and a period d311.

[0071] Combine Figure 10 and Figure 11 ,in, Figure 10 is the specific form of the grating distribution on the first principal plane of the optical waveguide plate SUB1 in scheme 2, Figure 11 This is the specific form of the grating distribution on the second principal plane of the optical waveguide plate SUB1 in the second solution. Specifically, the first principal plane is provided with diffraction grating DOE13 (i.e., the first entrance pupil grating element), DOE14 (i.e., the second entrance pupil grating element), and DOE303 (i.e., the first exit pupil grating element). The grating period (d) and grating direction (θ) of the diffraction grating can be determined by the grating vector V of the diffraction grating. The grating vector V can be defined as a vector having a direction perpendicular to the diffraction lines of the diffraction grating and an amplitude given by 2π / d, where d is the grating period (i.e., the fringe spacing). There is a grating vector V13 in the diffraction grating DOE13, with a direction θ13 and a period d13; there is a grating vector V14 in the diffraction grating DOE14, with a direction θ14 and a period d14; there is a grating vector V303 in the diffraction grating DOE303, with a direction θ303 and a period d303, and there may also be a grating vector V304 with a direction θ304 and a period d303.

[0072] On the second principal plane are diffraction grating DOE23 (i.e., the first pupil expansion grating element), DOE24 (i.e., the second pupil expansion grating element), and DOE313 (i.e., the second exit pupil grating element). Diffraction grating DOE23 contains a grating vector V23 with a direction θ23 and a period d23; diffraction grating DOE24 contains a grating vector V24 with a direction θ24 and a period d24; diffraction grating DOE313 contains a grating vector V313 with a direction θ313 and a period d313, and may also contain a grating vector V314 with a direction θ314 and a period d313.

[0073] In one embodiment, the first output transmission light formed by the first pupil expansion grating element and transmitted to the exit pupil unit and the second output transmission light formed by the second pupil expansion grating element and transmitted to the exit pupil unit propagate in opposite directions in the exit pupil unit area.

[0074] In a practical application scenario, Figure 4 and Figure 6 The first scheme shown is to set up a waveguide display device with dual light engines and dual entrance pupils. In this display device, the image light beam emitted by the first light engine 41 is irradiated onto the first entrance pupil unit 11. The diffraction grating DOE11 on the first entrance pupil unit 11 couples the image light beam emitted by the first light engine 41 into the optical waveguide plate SUB1, and forms the guided light light 1 that is guided toward the first pupil expansion unit 21 by total reflection. The diffraction grating DOE21 on the first pupil expansion unit 21 couples the guided light light 1 to form the guided light light 2 that is guided toward the exit pupil unit 31. The diffraction gratings DOE301 and DOE311 on the exit pupil unit 31 couple the guided light light 2 out of the optical waveguide to form the output image light.

[0075] In addition, the image light beam emitted by the second light engine 42 in the display device is irradiated onto the second entrance pupil unit 12. The diffraction grating DOE12 on the second entrance pupil unit 12 couples the image light beam emitted by the second light engine 42 into the optical waveguide plate SUB1, and forms the guided light light11 that is guided toward the second pupil expansion unit 22 in a total reflection manner. The diffraction grating DOE22 on the second pupil expansion unit 22 couples the guided light light11 to form the guided light light21 that is guided toward the exit pupil unit 31. The diffraction gratings DOE301 and DOE311 on the exit pupil unit 31 couple the guided light light21 out of the optical waveguide to form the output image light.

[0076] In another practical application scenario, Figure 5 and Figure 7The second scheme shown is used to set up a waveguide display device with dual light engines and dual entrance pupils. In this display device, the image light beam emitted by the first light engine 41 is irradiated onto the first entrance pupil unit 13. The diffraction grating DOE13 on the first entrance pupil unit 13 couples the image light beam emitted by the first light engine 41 into the optical waveguide plate SUB1, and forms the guided light light 1 that is guided toward the first pupil expansion unit 23 by total reflection. The diffraction grating DOE23 on the first pupil expansion unit 23 couples the guided light light 1 to form the guided light light 2 that is guided toward the exit pupil unit 32. The diffraction gratings DOE303 and DOE313 on the exit pupil unit 32 couple the guided light light 2 out of the optical waveguide to form the output image light.

[0077] In addition, the image light beam emitted by the second light engine 42 in the display device is irradiated onto the second entrance pupil unit 14. The diffraction grating DOE14 on the second entrance pupil unit 14 couples the image light beam emitted by the second light engine 42 into the optical waveguide plate SUB1, and forms a conductive light light11 that is transmitted to the second pupil expansion unit 24 in a total reflection manner. The diffraction grating DOE24 on the second pupil expansion unit 24 couples the conductive light light 11 to form a conductive light light 21 that is transmitted to the exit pupil unit 32. The diffraction gratings DOE303 and DOE313 on the exit pupil unit 32 couple the conductive light light 21 out of the optical waveguide to form the output image light).

[0078] Two embodiments are provided below to illustrate the waveguide principle of the dual-entry-pupil waveguide display device.

[0079] Example 1:

[0080] Example 1 uses Figure 4 and Figure 6 In the display device shown, the exit pupil unit 31 is located at the center of the optical waveguide plate SUB1, two pupil expansion units are located above and below the exit pupil unit 31, and two entrance pupil units are located on the left and right of the corresponding pupil expansion units. The entrance pupil unit, pupil expansion unit and exit pupil unit 31 respectively use diffraction gratings, see Figure 4 、 Figure 6 、 Figure 8 、 Figure 9 .

[0081] Figure 12 and Figure 13 As the wave vector diagram of the grating distribution in Example 1, the wave vector of the input light IN1 may exist in a region BOX0 of the wave vector space defined by the initial wave vectors kx and ky. Each corner of the region BOX0 may represent the wave vector of the light of a pixel point of the input image IMG0.

[0082] The small circle KTIR represents the first boundary for satisfying the total internal reflection (TIR) ​​criterion in the waveguide plate SUB1. The large circle Kmax represents the second boundary of the maximum wave vector in the waveguide plate SUB1. The wave vector boundary can be determined by the refractive index of the waveguide plate and the period of the diffraction grating. Light can be guided by total internal reflection in the waveguide plate only when the light wave vector is within the zone ZONE1 between the first boundary KTIR and the second boundary Kmax. If the light wave vector is outside the zone ZONE1, the light may leak out of the waveguide plate or not propagate at all.

[0083] in Figure 12 Corresponding to the first light engine 41, the diffraction grating DOE11, the diffraction grating DOE21, the diffraction grating DOE301 and the diffraction grating DOE311, the specific waveguide process is as follows:

[0084] Incident light IN1 enters the waveguide from region BOX0. First, right-propagating light B1 propagates toward V11, with its wave vector in region BOX1. Second, propagating light B2 propagates toward V21, with its wave vector in region BOX2. Third, propagating light B3 propagates toward V302, with its wave vector in region BOX3. Fourth, propagating light B4 propagates toward V312, with its wave vector in region BOX4. First, output light OUT1 propagates toward V312, with its wave vector in region BOX5. Second, output light OUT2 propagates toward V302, with its wave vector in region BOX6. According to waveguide theory, the paths of both wave vectors in the waveguide must be closed loops to ensure symmetry between the waveguide input and output.

[0085] Figure 13 Corresponding to the second light engine 42, the diffraction grating DOE12, the diffraction grating DOE22, the diffraction grating DOE301 and the diffraction grating DOE311, the specific waveguide process is as follows:

[0086] Incident light IN1 enters the optical waveguide SUB1 from area BOX0. The first left-transmitted light B1 is transmitted in the direction of V12, with its wave vector in area BOX1. The second left-transmitted light B2 is transmitted in the direction of V22, with its wave vector in area BOX2. The third left-transmitted light B3 is transmitted in the direction of V301, with its wave vector in area BOX3. The fourth left-transmitted light B4 is transmitted in the direction of V311, with its wave vector in area BOX4. The first output light OUT1 is transmitted in the direction of V311, with its wave vector in area BOX5. The second output light OUT2 is transmitted in the direction of V301, with its wave vector in area BOX6. According to waveguide theory, the paths of both wave vectors in the waveguide must be closed loops to ensure symmetry between the waveguide input and output.

[0087] This embodiment adopts a rotationally symmetrically distributed optical waveguide architecture, so that the image output light intensity distribution of different wavelengths in the exit pupil unit 31 is more uniform, and the light intensity distribution of each color is more consistent, thereby achieving higher brightness uniformity and color uniformity.

[0088] Example 2:

[0089] Example 2 uses Figure 5 and Figure 7 In the display device shown, the exit pupil unit 32 is located at the center of the optical waveguide plate SUB1, two pupil expansion units are located on the left and right sides of the exit pupil unit 32, and two entrance pupil units are located above and below the corresponding pupil expansion units. The entrance pupil unit, pupil expansion unit and exit pupil unit 32 respectively use diffraction gratings, see Figure 5 、 Figure 7 、 Figure 10 、 Figure 11 .

[0090] Figure 14 and Figure 15 As the wave vector diagram of the grating distribution in embodiment 2, the wave vector of the input light IN1 may exist in a region BOX0 of the wave vector space defined by the initial wave vectors kx and ky. Each corner of the region BOX0 may represent the wave vector of light of a pixel point of the input image IMG0.

[0091] The small circle KTIR represents the first boundary for satisfying the total internal reflection (TIR) ​​criterion in the optical waveguide plate SUB1. The large circle Kmax represents the second boundary of the maximum wave vector in the waveguide plate SUB1. The wave vector boundary can be determined by the refractive index of the waveguide plate and the period of the diffraction grating. Light can be guided by total internal reflection in the waveguide plate only when the light wave vector is within the zone ZONE1 between the first boundary KTIR and the second boundary Kmax. If the light wave vector is outside the zone ZONE1, the light may leak out of the waveguide plate or not propagate at all.

[0092] in Figure 14 Corresponding to the first light engine 41, the diffraction grating DOE13, the diffraction grating DOE23, the diffraction grating DOE303 and the diffraction grating DOE313, the specific waveguide process is as follows:

[0093] Incident light IN1 enters the optical waveguide SUB1 from region BOX0. First, downward-transmitted light B1 travels in the direction of V13, with its wave vector in region BOX1. Second, downward-transmitted light B2 travels in the direction of V23, with its wave vector in region BOX2. Third, downward-transmitted light B3 travels in the direction of V304, with its wave vector in region BOX3. Fourth, downward-transmitted light B4 travels in the direction of V314, with its wave vector in region BOX4. First, output light OUT1 travels in the direction of V314, with its wave vector in region BOX5. Second, output light OUT2 travels in the direction of V304, with its wave vector in region BOX6. According to waveguide theory, the paths of both wave vectors in this waveguide must be closed loops to ensure symmetry between the input and output of the waveguide.

[0094] Figure 13 Corresponding to the second light engine 42, the diffraction grating DOE14, the diffraction grating DOE24, the diffraction grating DOE303 and the diffraction grating DOE313, the specific waveguide process is as follows:

[0095] Incident light IN1 enters the optical waveguide SUB1 from region BOX0. First, upward-propagating light B1 propagates toward V14, with its wave vector in region BOX1. Second, upward-propagating light B2 propagates toward V24, with its wave vector in region BOX2. Third, upward-propagating light B3 propagates toward V303, with its wave vector in region BOX3. Fourth, upward-propagating light B4 propagates toward V313, with its wave vector in region BOX4. First, output light OUT1 propagates toward V313, with its wave vector in region BOX5. Second, output light OUT2 propagates toward V303, with its wave vector in region BOX6. According to waveguide theory, the paths of both wave vectors in this waveguide must be closed loops to ensure symmetry between the input and output of the waveguide.

[0096] This embodiment adopts a rotationally symmetrically distributed optical waveguide architecture, so that the image output light intensity distribution of different wavelengths in the exit pupil unit 32 is more uniform, and the light intensity distribution of each color is more consistent, thereby achieving higher brightness uniformity and color uniformity, and the display effect is equivalent to that of Example 1.

[0097] The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of this application, several improvements and modifications can be made to this application, and these improvements and modifications also fall within the scope of protection of the claims of this application.

[0098] It should also be noted that, in this specification, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus comprising the element.

Claims

1. A dual-entry-pupil waveguide display device, characterized in that: The optical waveguide unit includes an optical waveguide plate, the optical waveguide plate includes a first main plane and a second main plane, the first main plane is provided with a first entrance pupil grating element, a second entrance pupil grating element and a first exit pupil grating element; the second main plane is provided with a first pupil expansion grating element, a second pupil expansion grating element and a second exit pupil grating element; The first entrance pupil grating element constitutes a first entrance pupil unit, and the second entrance pupil grating element constitutes a second entrance pupil unit; the first exit pupil grating element and the second exit pupil grating element have at least a partial overlap in their projections in the thickness direction of the optical waveguide plate, and the two together constitute the exit pupil unit; the first entrance pupil grating element and the second entrance pupil grating element are rotationally symmetric about the center of the exit pupil unit; The dual-entry-pupil waveguide display device further includes a first light engine corresponding to the first entrance pupil unit, for providing a first image light; wherein the first entrance pupil grating element couples the first image light to form a first guided light transmitted to the first pupil expansion grating element; The dual-entry-pupil waveguide display device further includes a second light engine corresponding to the second entrance pupil unit, for providing a second image light; wherein the second entrance pupil grating element couples the second image light to form a second guided light transmitted to the second pupil expansion grating element; The first pupil expansion grating element receives the first transmitted light and forms a first turned transmitted light transmitted to the exit pupil unit. The second pupil expansion grating element receives the second transmitted light and forms a second turned transmitted light transmitted to the exit pupil unit. The first turned transmitted light and the second turned transmitted light are coupled out by the exit pupil unit to form output image light.

2. The dual-entry-pupil waveguide display device according to claim 1, wherein: The grating periods of all grating elements arranged on the first main plane are the same, and the grating periods of all grating elements arranged on the second main plane are the same.

3. The dual-entry-pupil waveguide display device according to claim 1, wherein: The grating period of all grating elements arranged on the first principal plane is the same as the grating period of all grating elements arranged on the second principal plane.

4. The dual-entry-pupil waveguide display device according to claim 1, wherein: The images displayed by the first light engine and the second light engine are identical or symmetrical or rotationally symmetrical to each other.

5. The dual-entry-pupil waveguide display device according to claim 1, wherein: The first exit pupil grating element and the second exit pupil grating element are projected and overlapped in the thickness direction of the optical waveguide plate.

6. The dual-entry-pupil waveguide display device according to claim 1, wherein: The first pupil expansion grating element and the second pupil expansion grating element are rotationally symmetric about the center of the exit pupil unit.

7. The dual-entry-pupil waveguide display device according to claim 1, wherein: The first turning transmission light formed by the first pupil expansion grating element and transmitted to the exit pupil unit and the second turning transmission light formed by the second pupil expansion grating element and transmitted to the exit pupil unit propagate in opposite directions in the exit pupil unit area.

8. The dual-entry-pupil waveguide display device according to claim 1, wherein: The first light engine and the second light engine are located on the same side or different sides of the optical waveguide plate.

9. The dual-entry-pupil waveguide display device according to claim 1, wherein: The first pupil expansion grating element constitutes a first pupil expansion unit, and the second pupil expansion grating element constitutes a second pupil expansion unit; The first pupil expansion unit and the second pupil expansion unit are respectively located on the upper and lower sides or the left and right sides of the exit pupil unit.

10. The dual-entry-pupil waveguide display device according to claim 9, wherein: When the first pupil expansion unit and the second pupil expansion unit are respectively located on the upper and lower sides of the exit pupil unit, the grating vector directions of the first entrance pupil grating element and the second entrance pupil grating element are arranged horizontally; When the first pupil expansion unit and the second pupil expansion unit are respectively located on the left and right sides of the exit pupil unit, the grating vector directions of the first entrance pupil grating element and the second entrance pupil grating element are arranged vertically; The included angle between the grating vector directions of the first exit pupil grating element and the second exit pupil grating element is 50° to 70°.

Images