Near-to-eye display equipment and display device

Abstract

The invention discloses near-to-eye display equipment and a display device, and aims to solve the problem of poor brightness uniformity of near-to-eye display equipment in the prior art. The near-eye display device includes: an optical waveguide; the display structure is located at one end of the optical waveguide; the coupling-in grating and the display structure are located at the same end of the optical waveguide, and the coupling-in grating is provided with a plurality of first slits and is configured to couple incident light of the display structure into the optical waveguide; the turning grating and the coupling-in grating are located at the same end of the optical waveguide, and the turning grating is provided with a plurality of second slits and is configured to change the propagation direction of part of light coupled in by the coupling-in grating; the coupling-out grating is located at the other end of the optical waveguide, is provided with a plurality of third slits and is configured to couple out light transmitted by the optical waveguide; the inclination direction of the first slit is the same as the inclination direction of the second slit.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a near-eye display device and a display apparatus. Background Art

[0002] In the conventional augmented reality (AR) diffraction waveguide design, the light emitted by the display screen is collimated by the projection system and then coupled in through the coupling grating. The light is transmitted by total reflection in the optical waveguide, and the light is continuously taken out through the coupling grating to achieve one-dimensional pupil expansion. The pupil is expanded in another direction through the folding grating to achieve two-dimensional pupil expansion. The grating is coupled in through the coupling grating, the pupil is expanded through the folding grating, and the pupil is expanded in another direction through the coupling grating. Finally, the grating is coupled out by the coupling grating, received by the human eye, and imaged on the retina.

[0003] However, the brightness uniformity of waveguide AR display cannot be improved by adjusting the structural parameters of the grating. Summary of the invention

[0004] The present invention provides a near-eye display device and a display apparatus to improve the problem of poor brightness uniformity of the near-eye display device in the prior art.

[0005] An embodiment of the present invention provides a near-eye display device, including:

[0006] Optical waveguides;

[0007] A display structure located at one end of the optical waveguide;

[0008] A coupling grating, located at the same end of the optical waveguide as the display structure, having a plurality of first slits and configured to couple light incident from the display structure into the optical waveguide;

[0009] A folding grating, located at the same end of the optical waveguide as the coupling-in grating, having a plurality of second slits and configured to change the propagation direction of a portion of the light coupled in by the coupling-in grating;

[0010] An outcoupling grating, located at the other end of the optical waveguide, having a plurality of third slits and configured to couple out the light propagating from the optical waveguide;

[0011] Wherein, the inclination direction of the first slit is the same as the inclination direction of the second slit.

[0012] In a possible implementation manner, an inclination angle of the first slit is smaller than an inclination angle of the second slit.

[0013] In a possible implementation, the optical waveguide includes: a first side extending along a first direction, and a second side extending along a second direction; the coupling-in grating and the coupling-out grating are distributed at two ends of the optical waveguide along the first direction, and the coupling-in grating and the folding grating are distributed at two ends of the optical waveguide along the second direction;

[0014] The angle formed by the side of the first slit facing the outcoupling grating and the first direction is an acute angle.

[0015] In a possible implementation manner, an angle formed by a side of the first slit facing the outcoupling grating and the first direction is in a range of 0° to 45°.

[0016] In a possible implementation manner, an angle formed by a side of the second slit facing the outcoupling grating and the first direction is in a range of 35° to 135°.

[0017] In a possible implementation manner, the projection of the outer contour of the folding grating on the optical waveguide is a trapezoid, and the top edge of the trapezoid is arranged close to the coupling grating;

[0018] The bottom angle of the trapezoid facing the outcoupling grating is greater than the bottom angle of the trapezoid away from the outcoupling grating.

[0019] In a possible implementation manner, the bottom angle of the trapezoid facing the outcoupling grating is in the range of 80° to 100°.

[0020] In a possible implementation manner, the bottom angle of the trapezoid facing the outcoupling grating is a right angle.

[0021] In a possible implementation, the outcoupling grating includes a plurality of outcoupling sub-regions along the first direction, and in a direction from the incoupling grating to the outcoupling grating, the grating heights of the outcoupling sub-regions increase sequentially.

[0022] In a possible implementation, the outcoupling grating includes an outcoupling center;

[0023] The near-eye display device also includes: an eye box structure located at the same end of the optical waveguide as the outcoupling grating; the eye box structure center is an orthographic projection of the optical waveguide, which does not coincide with the center of the orthographic projection of the outcoupling center on the optical waveguide, and is located on the side of the outcoupling center facing the folding grating.

[0024] In a possible implementation manner, in the direction from the coupling-in grating to the coupling-out grating, the plurality of coupling-out partitions include: a first coupling-out partition, a second coupling-out partition and a third coupling-out partition;

[0025] The orthographic projection of the center of the eye box structure on the optical waveguide has an overlapping area with the orthographic projection of the second outcoupling partition on the optical waveguide, and has an overlapping area with the orthographic projection of the first outcoupling partition on the optical waveguide.

[0026] In a possible implementation, the grating heights of the same outcoupling subarea are the same.

[0027] In a possible implementation manner, the third slit extends along the second direction.

[0028] In a possible implementation, the coupling-in grating has a first grating vector, the vector direction of the first grating vector is perpendicular to the direction of the first slit; the folding grating has a second grating vector, the vector direction of the second light vector is perpendicular to the direction of the second slit; the coupling-out grating has a third grating vector, the vector direction of the third grating vector is perpendicular to the direction of the third slit;

[0029] The sum of the first grating vector, the second grating vector and the third grating vector is zero.

[0030] An embodiment of the present disclosure also provides a display device, comprising the near-eye display device provided in the embodiment of the present disclosure.

[0031] The beneficial effects of the embodiments of the present invention are as follows: In the embodiments of the present invention, by adjusting the extension direction of the first slit of the coupling-in grating 3, the inclination direction of the first slit of the coupling-in grating is made the same as the inclination direction of the second slit of the folding grating, so that the main axis of light propagation can be brought closer to the direction of the coupling-out grating, and the light transmitted to the edge of the waveguide glasses can be reduced. The transmission length of the positive-angle light in the folding grating can be reduced, and the light waste can be effectively reduced, so that part of the negative-angle light is not transmitted to the folding grating. Furthermore, the brightness of the negative-angle light is reduced and the brightness of the positive-angle light is increased to achieve the improvement of brightness uniformity. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 One of the cross-sectional structural schematic diagrams of a near-eye display device provided by an embodiment of the present invention;

[0033] Figure 2 For Figure 1 One of the corresponding top view schematic diagrams of each grating;

[0034] Figure 3 This is a schematic diagram of the simulation of light transmission in an optical waveguide;

[0035] Figure 4 A schematic diagram showing the comparison of total reflection step lengths when light of different wavelengths is transmitted in an optical waveguide;

[0036] Figure 5This is one of the schematic diagrams of the angular brightness distribution of the system when the coupling-in grating, the folding grating and the coupling-out grating are ideal gratings;

[0037] Figure 6 The second schematic diagram of the angular brightness distribution of the system when the coupling-in grating, the folding grating and the coupling-out grating are ideal gratings;

[0038] Figure 7 is a schematic diagram of the grating structure;

[0039] Figure 8 Schematic diagram of the diffraction efficiency distribution of the coupled grating;

[0040] Fig. 9 The brightness distribution of the system corresponds to different diffraction efficiencies of the coupled gratings;

[0041] Fig.10 is the angular brightness distribution of the two lines at the center of the system angular brightness distribution;

[0042] Fig.11 One of the top view schematic diagrams of each grating provided in the embodiment of the present disclosure;

[0043] Fig.12 Schematic diagram of the transmission of collimated light (0° light) in an optical waveguide after being coupled into an input grating;

[0044] Fig.13 Schematic diagram of light transmission after the coupled grating lines rotate;

[0045] Fig.14 This is a schematic diagram of the angular brightness distribution of the system after the direction of the coupled grating lines is changed;

[0046] Fig.15 The second schematic diagram of the angular brightness distribution of the system after the direction of the coupled grating lines is changed;

[0047] Fig.16 The third schematic diagram of the angular brightness distribution of the system after the direction of the coupled grating lines is changed;

[0048] Fig.17 The distribution of grating lines after the direction of the coupled grating lines is rotated in the opposite direction;

[0049] Fig.18 This is a schematic diagram of the angular brightness distribution of the system after the direction of the coupled grating lines is rotated in the opposite direction;

[0050] Fig.19 The second schematic diagram of the angular brightness distribution of the system after the direction of the coupled grating lines is rotated in the opposite direction;

[0051] Fig. 20 The third schematic diagram of the angular brightness distribution of the system after the direction of the coupled grating lines is rotated in the opposite direction;

[0052] Fig.21 One of the structural schematic diagrams for adjusting the bottom angle of the folded grating toward the out-coupling grating;

[0053] Fig. 22 One of the schematic diagrams of the brightness distribution of the system when the bottom angle of the folding grating toward the out-coupling grating is adjusted;

[0054] Fig.23 The second schematic diagram of the system brightness distribution when the bottom angle of the folded grating toward the out-coupling grating is adjusted;

[0055] Fig.24 The third schematic diagram of the system brightness distribution when the bottom angle of the folded grating toward the out-coupling grating is adjusted;

[0056] Fig.25 The second structural schematic diagram is for adjusting the bottom angle of the folded grating toward the out-coupling grating;

[0057] Fig.26 The third structural schematic diagram is for adjusting the bottom angle of the folded grating toward the out-coupling grating;

[0058] Fig. 27 One of the schematic diagrams of the brightness distribution of the system when the bottom angle of the folding grating toward the out-coupling grating is adjusted;

[0059] Fig.28 The second schematic diagram of the system brightness distribution when the bottom angle of the folded grating toward the out-coupling grating is adjusted;

[0060] Fig.29 This is one of the schematic diagrams of the folded grating shape;

[0061] Fig.30 It is a schematic diagram of the arrangement of gratings at various positions of the optical waveguide;

[0062] Fig.31 for Fig.30 One of the corresponding system brightness distribution diagrams;

[0063] Fig.32 for Fig.30 The corresponding schematic diagram of the system brightness distribution in horizontal and vertical directions;

[0064] Fig.33 for Fig.30 Schematic diagram of the corresponding normalized system brightness distribution in horizontal and vertical directions. DETAILED DESCRIPTION

[0065] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0066] Unless otherwise defined, the technical terms or scientific terms used in the present disclosure should be understood by people with ordinary skills in the field to which the present disclosure belongs. The "first", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0067] As used herein, "approximately" or "substantially the same" includes the stated value and means within an acceptable range of deviation for the particular value as determined by one of ordinary skill in the art taking into account the measurement in question and the errors associated with the measurement of the particular quantity (i.e., the limitations of the measurement system). For example, "substantially the same" may mean that the difference relative to the stated value is within one or more standard deviations, or within ±30%, 20%, 10%, 5%.

[0068] In the accompanying drawings, the thickness of layers, films, panels, regions, etc., is exaggerated for clarity. Exemplary embodiments are described herein with reference to cross-sectional views as schematic diagrams of idealized embodiments. In this way, deviations from the shapes of the figures as a result of, for example, manufacturing techniques and / or tolerances will be expected. Thus, the embodiments described herein should not be interpreted as being limited to the specific shapes of the regions as shown herein, but include deviations in shape caused by, for example, manufacturing. For example, a region illustrated or described as flat may typically have rough and / or nonlinear features. In addition, the illustrated sharp corners may be rounded. Thus, the regions shown in the figures are schematic in nature, and their shapes are not intended to illustrate the precise shapes of the regions, and are not intended to limit the scope of the claims.

[0069] In order to keep the following description of the embodiments of the present disclosure clear and concise, the present disclosure omits detailed descriptions of well-known functions and well-known components.

[0070] See also Figure 1 and Figure 2 As shown, a conventional near-eye display device may include: a projection system, a coupling-in grating / coupling-out grating, a folding grating, and an optical waveguide; wherein the projection system may include a display screen and a light collimation system for collimating the light emitted from the screen; the periods of the coupling-in grating and the coupling-out grating may be the same, the line direction of the coupling-in grating may be horizontal, and the line direction of the coupling-out grating may be vertical, specifically, the coupling-in and coupling-out gratings may be relief gratings or holographic gratings; the line direction of the folding grating is as shown in FIG. 2, and is at an angle of 45° to the horizontal direction, and the folding grating is used to expand the light coupled into the coupling-in grating in another dimension; the optical waveguide may specifically be flat glass, or may be high-folding glass, which is used to reduce the total reflection angle, increase the angle range of transmission in the waveguide, and increase the field of view of the waveguide display.

[0071] like Figure 3 The figure shows a schematic diagram of light transmission simulation of a near-eye display device. The basic display principle can be as follows: the coupling-in grating couples the collimated light emitted by the light collimation system into the optical waveguide for total reflection transmission. When the light is transmitted to the deflection grating, the light is divided into two parts. One part continues to be transmitted forward by total reflection to achieve light expansion in the Y direction (Y-direction pupil expansion), and the other part is transmitted by total reflection in the direction of the coupling-out grating. After the light is transmitted to the coupling-out grating, it is coupled out by the coupling-out grating, enters the human eye, and is imaged on the retina.

[0072] However, conventional near-eye display devices currently have the problem of poor angular brightness uniformity. The inventors of this application have studied the reasons for the poor brightness uniformity of light waveguide displays, as follows:

[0073] d(n0sini-n1sinθ)=mλ;

[0074] According to the above grating equation, the diffraction angle of incident light with a small angle after being modulated by the incident grating is small, and the step length of total reflection in the optical waveguide is small, as shown in the following example: Figure 4 As shown, wherein n0=1, n1=1.9, d=415nm, m=-1, i=±16°, and the thickness of the optical waveguide is 1mm;

[0075] When the diffraction efficiency distribution of the coupling-in grating, the folding grating and the coupling-out grating is a straight line (i.e., an ideal grating), that is, the diffraction efficiency at different angles is the same, at this time, the total reflection step lengths of light with different incident angles in the waveguide are different, and the number of times the coupled-out grating is taken out is different, such as Figure 5 and Figure 6 As shown, where H corresponds to Figure 3 The X direction corresponds to the V direction Figure 3 In the Y direction, the system angular brightness distribution is uneven and the brightness uniformity is poor.

[0076] The conventional method is to optimize the structural parameters of the grating, such as period, duty cycle, grating height, and grating tilt angle to optimize the diffraction efficiency distribution of the grating. Figure 7 As shown. A rectangular grating (β = 90°) is currently used. Therefore, the duty cycle and grating height of the grating are optimized under the selected grating period, so that the diffraction efficiency distribution of the coupled grating is as follows: Figure 8 As shown, the folding grating and the outcoupling grating are still ideal gratings. At this time, the angular brightness distribution of the system is as follows: Fig. 9 and Fig.10 As shown, it can be seen that the angular brightness distribution in the H direction can be improved by adjusting the diffraction efficiency distribution of the coupling-in grating, but the angular brightness distribution in the V direction cannot be improved. Similarly, when using a folding grating and an out-coupling grating with different diffraction efficiency distributions, the diffraction efficiency distribution of the folding grating can only improve the angular brightness distribution in the H direction, and the angular brightness in the V direction has a small change. The diffraction efficiency distribution of the out-coupling grating cannot improve the angular brightness distribution of the system (the diffraction efficiency does not change much). Therefore, the brightness uniformity distribution of the system cannot be achieved by only changing the structural parameters of the grating.

[0077] In view of this, combined with Figure 1 and Fig.11 As shown, Fig.11 Can be Figure 1 Corresponding top view schematic diagram, an embodiment of the present invention provides a near-eye display device, including:

[0078] Optical waveguide 1; specifically, the optical waveguide 1 may be flat glass or high-refractive glass;

[0079] The display structure 2 is located at one end of the optical waveguide 1. Specifically, for example, the display structure 2 may be located at Figure 1 The right end of the optical waveguide 1;

[0080] The coupling grating 3 is located at the same end of the optical waveguide 1 as the display structure 2, has a plurality of first slits S1, and is configured to couple the light incident from the display structure 2 into the optical waveguide 1; specifically, for example, the coupling grating 3 may also be located at Figure 1 The right end of the optical waveguide 1;

[0081] The folding grating 4 and the coupling grating 3 are located at the same end of the optical waveguide 1. Specifically, for example, the coupling grating 3 can also be located at Figure 1 The right end of the optical waveguide 1; the folding grating 4 has a plurality of second slits S2, which are configured to change the propagation direction of part of the light coupled into the coupling grating 3; specifically, the folding grating 4 can divide the light into two parts, one part of which is transmitted by total reflection in the direction of the coupling-out grating 5 (such as Fig.12 The other part is totally reflected and transmitted in the direction perpendicular to the X direction (such as Fig.12The light transmitted along the Y direction in the image is realized to expand the light in the Y direction (the pupil is expanded in the Y direction);

[0082] The outcoupling grating 5 is located at the other end of the optical waveguide 1. Specifically, for example, the outcoupling grating 5 can also be located at Figure 1 The left end of the optical waveguide 1; the outcoupling grating 5 has a plurality of third slits S3, which are configured to couple out the light propagating from the optical waveguide 1;

[0083] The inclination direction of the first slit S1 is the same as the inclination direction of the second slit S2.

[0084] Specifically, combined with Fig.12 As shown, Fig.12 This is a simulation diagram of light transmission in an optical waveguide. After the collimated light (0° light) is coupled into the coupling grating, it is totally reflected and propagates to the folding grating. The folding grating divides the light into two parts. One part is transmitted forward (i.e., transmitted along the Y direction, i.e., Figure 1 In the embodiment of the present invention, one part of the light is transmitted toward the out-coupling grating (i.e., transmitted along the X direction. When the light is transmitted toward the out-coupling grating, the light will be divided into two parts, one transmitted forward and the other transmitted toward the out-coupling grating, when the light hits the folding grating. The light transmitted forward (in the Y direction) will continue to be totally reflected in the optical waveguide when it reaches the end of the folding grating, and will be transmitted to the edge of the optical waveguide glasses. It will not enter the human eye and cause waste in the end. Therefore, this part of the light should be minimized. The amount of light transmitted to the edge of the waveguide glasses is different for different incident angles. In the embodiment of the present invention, by adjusting the extension direction of the first slit S1 of the coupling-in grating 3, the inclination direction of the first slit S1 of the coupling-in grating 3 is made the same as the inclination direction of the second slit S2 of the folding grating 4. This can make the main axis of light propagation close to the out-coupling grating 5, thereby reducing the light transmitted to the edge of the optical waveguide glasses. Fig.13 The thick solid line in the middle indicates the position of light rays at different angles reaching the edge of the folding grating when the coupled grating lines (i.e., the first slit S1) are not rotated. It can be seen that the right side (positive angle light rays) causes the most light waste, while the left side (negative angle light rays) causes the least light waste. Therefore, the direction of the light rays transmitted to the folding grating 4 is rotated, as shown in FIG. Fig.13 As shown by the black dotted line in the figure, at this time, the transmission length of the positive-angle light on the right side in the folding grating is reduced, which can effectively reduce the waste of light, while part of the negative-angle light on the left side is not transmitted to the folding grating 4. Furthermore, the brightness uniformity is improved by reducing the brightness of the negative-angle light and increasing the brightness of the positive-angle light.

[0085] In one possible implementation, see Fig.11As shown, the tilt angle of the first slit S1 is smaller than the tilt angle of the second slit S2. In this way, while improving the brightness uniformity of the near-eye display device, the tilt angle of the first slit S1 is prevented from being too large, which would affect the normal coupling effect of the coupling grating 3 on light.

[0086] In one possible implementation, see Fig.11 As shown, the optical waveguide 1 includes: a first side A1 extending along a first direction, and a second side A2 extending along a second direction Y; the coupling-in grating 3 and the coupling-out grating 4 are distributed at both ends of the optical waveguide 1 along the first direction X, that is, the coupling-in grating 3 and the coupling-out grating 4 are distributed at both ends of the optical waveguide 1 along the extension direction of the first side A1; the coupling-in grating 3 and the folding grating 4 are distributed at both ends of the optical waveguide 1 along the second direction Y, that is, the coupling-in grating 3 and the folding grating 4 are distributed at both ends of the optical waveguide 1 along the extension direction of the second side A2; the angle formed by the side of the first slit S1 facing the coupling-out grating 5 and the first direction X is an acute angle. In a possible embodiment, when the cross-section of the optical waveguide 1 perpendicular to the thickness direction is a rectangle, the first side A1 can be the long side of the optical waveguide 1, and the second side A2 can be the short side of the optical waveguide 1; in another possible embodiment, the first side A1 can also be the short side of the optical waveguide 1, and the second side A2 can also be the long side of the optical waveguide 1.

[0087] In one possible implementation, see Fig.11 As shown, the angle formed by the side of the first slit S1 facing the outcoupling grating 5 and the first direction X is in the range of 0° to 45°; specifically, the angle formed by the side of the first slit S1 facing the outcoupling grating 5 and the first direction X is in the range of 5° to 15°. Specifically, the angle formed by the side of the first slit S1 facing the outcoupling grating 5 and the first direction is 5°, 6°, 7°, 8°, 9°, 10°, 11°, 12°, 13°, 14°, or 15°.

[0088] In one possible implementation, see Fig.11 As shown, the angle formed by the side of the second slit S2 facing the outcoupling grating and the first direction is in the range of 35° to 135°; specifically, the angle formed by the side of the second slit S2 facing the outcoupling grating and the first direction is in the range of 45° to 135°; specifically, the angle formed by the side of the second slit S2 facing the outcoupling grating and the first direction is in the range of 35° to 45°. The angle formed by the side of the second slit S2 facing the outcoupling grating and the first direction can be 35°, 36°, 37°, 38°, 39°, 40°, 41°, 42°, 43°, 44° or 45°.

[0089] In one possible implementation, see Fig.11As shown, the angle formed by the first slit S1 facing the out-coupling grating 5 and the first direction is 10°, the angle formed by the second slit S2 facing the out-coupling grating and the first direction is 40°, and the third slit S3 extends along the second direction Y. Specifically, the vector directions of the coupling-in grating 3, the folding grating 4 and the out-coupling grating 5 need to satisfy a triangle, that is, the sum of the grating vectors of the three gratings is zero. In the embodiment of the present disclosure, on the basis that the gratings are all ideal gratings, the direction of the grating lines of the original coupling-in grating 3 is changed, and the direction of the lines of the folding grating 4 is changed at the same time. For the convenience of processing, the direction of the lines of the out-coupling grating 5 may not be changed ( Fig.11 The direction of the middle line represents the direction of the grating line in the actual processing process), so that the light can be normally coupled in and out.

[0090] In one possible implementation, combining Fig.11 As shown, the third slit S3 of the outcoupling grating 5 can extend along the second direction Y.

[0091] Specifically, the coupling-in grating 3 has a first grating vector, and the vector direction of the first grating vector is perpendicular to the direction of the first slit S1; the folding grating 4 has a second grating vector, and the vector direction of the second light vector is perpendicular to the direction of the second slit S2; the coupling-out grating 5 has a third grating vector, and the vector direction of the third grating vector is perpendicular to the direction of the third slit S3; the sum of the first grating vector, the second grating vector, and the third grating vector is zero.

[0092] Specifically, after changing the slit directions of the coupling grating 3 and the folding grating 4, the diffraction characteristics of the grating are processed as ideal gratings, that is, the diffraction efficiency does not change with the change of angle. At this time, the angular brightness distribution of the system is as follows: Figure 14-16 As shown; as a comparison, the line direction of the coupled grating 3 (ie, the direction of the first slit S1) is rotated in the opposite direction, as Fig.17 The corresponding system angular brightness distribution is shown as Figure 18-Figure 20 As shown, by comparison, it is found that the brightness uniformity of the system decreases; according to Figure 14-Figure 20 It can be obtained that after changing the line direction of the coupling-in grating 3, the angular brightness distribution trend in the H direction remains basically unchanged, while the angular brightness trend in the V direction changes, that is, by tilting the grating vector of the coupling-in grating 3 toward the coupling-out grating 5 side, the angular brightness uniformity in the V direction can be significantly improved, that is, by optimizing the grating vector direction of the coupling-in grating 3, the brightness uniformity of the system in the V direction is optimized.

[0093] In a possible implementation manner, the brightness uniformity of the system in the V direction can also be improved by optimizing the shape of the folding grating 4. Specifically, Fig.21As shown, the angular brightness uniformity can be improved by optimizing the angle θ of the folding grating 4 close to the grating 5 side. Specifically, the angle θ of the folding grating 4 close to the grating 5 side is set to 72°, 90°, 65°, and 100° respectively. Through the study of the influence on the system brightness, the comparison diagram of the brightness curves in different directions is shown in FIG. Figure 22-Figure 24 As shown in the figure (the diffraction efficiency of the grating does not change with the incident angle, so the influence of a single variable, namely θ, on the angular brightness distribution of the system can be analyzed), by comparison, it can be found that when the angle θ of the folded grating 4 close-coupled to the grating 5 side changes, it has little effect on the angular brightness change trend in the H direction, but has a greater effect on the angular brightness uniformity in the V direction, that is, changing θ can achieve an improvement in the angular brightness uniformity in the V direction.

[0094] In one possible implementation, see Fig.25 and Fig.26 As shown, the projection of the outer contour of the folding grating 4 on the optical waveguide 1 is a trapezoid, and the top side of the trapezoid is arranged close to the coupling-in grating 3; the bottom angle θ1 of the trapezoid facing the coupling-out grating 5 is greater than the bottom angle θ2 of the trapezoid away from the coupling-out grating 5. In the disclosed embodiment, the bottom angle θ1 of the folding grating 4 facing the coupling-out grating 5 is greater than the bottom angle θ2 of the side away from the coupling-out grating 5, which can also improve the uniformity of the angular brightness of the near-eye display device.

[0095] In a possible implementation, the projection of the outer contour of the folding grating 4 on the optical waveguide 1 is a trapezoid, which may be a trapezoid projected at a right angle, such as Fig.25 or Fig.26 It can also be a trapezoid with the bottom corner facing the outcoupling grating 5 removed, such as Fig.30 shown.

[0096] In a possible implementation manner, the bottom angle of the trapezoid facing the outcoupling grating is in the range of 80° to 100°. In a possible implementation manner, the bottom angle of the trapezoid facing the outcoupling grating is a right angle.

[0097] Specifically, when the coupling grating adopts Figure 7 The diffraction efficiency distribution shown in the figure is that the angle θ of the grating 4 is 90°. At this time, the angular brightness distribution of the system is as follows: Fig. 27 and Fig.28 As shown, at this time, the brightness uniformity of the system is improved in both the H direction and the V direction, and the brightness uniformity is >50%.

[0098] When the brightness uniformity of the near-eye display device is improved by changing the shape of the folding grating 4, while the brightness uniformity is improved, there is a partial angle loss ( Fig.28 This is because when the angle θ of the folding grating 4 toward the outcoupling grating 5 is 90°, some light cannot be taken out, such as Fig.29 As shown, the dotted line represents the incident angle boundary in the V direction (specifically, for example, ±16°). When the folding grating θ takes 90°, part of the light in the field of view cannot be transmitted to the coupling grating 5 and coupled out to the human eye by the coupling grating 5, resulting in an angle missing phenomenon. That is, simply changing the angle θ of the folding grating cannot balance the brightness uniformity in the V direction and the integrity of the field of view angle. Therefore, it is necessary to comprehensively consider the grating vector of the coupling grating 3 and the morphology of the folding grating 4 to achieve brightness uniformity at a large field of view angle.

[0099] In a possible implementation, the angular brightness uniformity of the system can also be improved by partitioning the outcoupling grating 5. For details, see Fig.30 As shown, the outcoupling grating 5 includes a plurality of outcoupling partitions 50 along the first direction X, and the grating heights of the outcoupling partitions 50 increase in sequence from the direction pointed by the coupling-in grating 3 to the outcoupling grating 5, so that different diffraction efficiencies can be achieved; specifically, from the direction pointed by the coupling-in grating 3 to the outcoupling grating 5, the plurality of outcoupling partitions 50 include: a first outcoupling partition 51, a second outcoupling partition 52 and a third outcoupling partition 53, from the direction pointed by the coupling-in grating 3 to the outcoupling grating 5, the grating height of the first outcoupling partition 51 is less than the grating height of the second outcoupling partition 52, the grating height of the second outcoupling partition 52 is less than the grating height of the third outcoupling partition 53, and the diffraction efficiencies of the first outcoupling partition 51, the second outcoupling partition 52 and the third outcoupling partition 53 can be 2%, 5% and 7%, respectively. Specifically, the grating heights of the same outcoupling partition 50 are the same. Specifically, in combination with Figure 7 As shown, the grating height can be understood as the height of the grating in the direction perpendicular to the thickness of the optical waveguide.

[0100] For details, see Fig.30 As shown, the outcoupling grating 5 includes an outcoupling center O1; the near-eye display device further includes: an eye box structure 6 located at the same end of the optical waveguide 1 as the outcoupling grating 5; the orthographic projection of the center O2 of the eye box structure 6 on the optical waveguide 1 does not coincide with the center of the orthographic projection of the outcoupling center O1 on the optical waveguide 1, and is located on the side of the outcoupling center O1 facing the folding grating 4. For details, see Fig.30 As shown, the orthographic projection of the center O2 of the eye box structure 6 on the optical waveguide 1 has an overlapping area with the orthographic projection of the second outcoupling partition 52 on the optical waveguide 1, and has an overlapping area with the orthographic projection of the first outcoupling partition 51 on the optical waveguide 1. In the embodiment of the present disclosure, the center of the outcoupling grating 5 is offset from the eye box structure 6 (i.e., the center of the human eye), which can improve the uniformity of system brightness.

[0101] Specifically, the first grating vector of the coupling-in grating 3 is deflected by -10° (that is, the angle formed by the side of the first slit S1 facing the coupling-out grating 5 and the first direction X is 10°), the angle θ of the folding grating 4 is 90° (that is, the bottom angle of the folding grating 4 facing the side of the coupling-out grating 5 is a right angle), the coupling-out grating 5 is divided into three coupling-out partitions (from the direction of the coupling-in grating 3 to the coupling-out grating 5, the three coupling-out partitions 50 are: the first coupling-out partition 51, the second coupling-out partition 52 and the third coupling-out partition 53, and the diffraction efficiencies of the first coupling-out partition 51, the second coupling-out partition 52 and the third coupling-out partition 53 can be ∼2%, 5%, and 7%, respectively), the coupling-out center O1 deviates from the center O2 of the eye box structure 6 (that is, the human eye eyebox) by 3mm, that is, the center of the human eye eyebox is offset by 3mm to the side of the folding grating 5, and the angular brightness distribution of the final system is as follows: Fig.31 As shown, the system brightness distribution results and normalization in the horizontal and vertical directions are as follows Fig.32 and Fig.33 As shown by Figure 31-Figure 33 It can be seen that the system has high angular brightness uniformity in the H and V directions. Within the ±14° field of view, the brightness uniformity is >50%.

[0102] In the embodiment of the present disclosure, by adjusting the extension direction of the first slit S1 of the coupling-in grating 3 so that the inclination direction of the first slit S1 of the coupling-in grating 3 is the same as the inclination direction of the second slit S2 of the folding grating 4, the main axis of light propagation can be brought closer to the direction of the coupling-out grating 5, reducing the light transmitted to the edge of the waveguide glasses, and reducing the transmission length of the positive-angle light in the folding grating, which can effectively reduce the waste of light and prevent part of the negative-angle light from being transmitted to the folding grating. Furthermore, by reducing the brightness of the negative-angle light and increasing the brightness of the positive-angle light, the brightness uniformity can be improved.

[0103] Based on the same inventive concept, the embodiment of the present disclosure further provides a display device, including the above-mentioned near-eye display device provided by the embodiment of the present disclosure. The implementation of the display device can refer to the above-mentioned embodiment of the display panel, and the repeated parts will not be repeated.

[0104] In the embodiment of the present disclosure, by adjusting the extension direction of the first slit S1 of the coupling-in grating 3 so that the inclination direction of the first slit S1 of the coupling-in grating 3 is the same as the inclination direction of the second slit S2 of the folding grating 4, the main axis of light propagation can be brought closer to the direction of the coupling-out grating 5, reducing the light transmitted to the edge of the waveguide glasses, and reducing the transmission length of the positive-angle light in the folding grating, which can effectively reduce the waste of light and prevent part of the negative-angle light from being transmitted to the folding grating. Furthermore, by reducing the brightness of the negative-angle light and increasing the brightness of the positive-angle light, the brightness uniformity can be improved.

[0105] Although the preferred embodiments of the present disclosure have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present disclosure.

[0106] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A near-eye display device, characterized in that: include: Optical waveguides; A display structure located at one end of the optical waveguide; A coupling grating, located at the same end of the optical waveguide as the display structure, having a plurality of first slits and configured to couple light incident from the display structure into the optical waveguide; A folding grating, located at the same end of the optical waveguide as the coupling-in grating, having a plurality of second slits and configured to change the propagation direction of a portion of the light coupled in by the coupling-in grating; An outcoupling grating, located at the other end of the optical waveguide, having a plurality of third slits and configured to couple out the light propagating from the optical waveguide; Wherein, the inclination direction of the first slit is the same as the inclination direction of the second slit.

2. The near-eye display device according to claim 1, characterized in that: The inclination angle of the first slit is smaller than the inclination angle of the second slit.

3. The near-eye display device according to claim 1 or 2, characterized in that: The optical waveguide comprises: a first side extending along a first direction, and a second side extending along a second direction; the coupling-in grating and the coupling-out grating are distributed at two ends of the optical waveguide along the first direction, and the coupling-in grating and the folding grating are distributed at two ends of the optical waveguide along the second direction; The angle formed by the side of the first slit facing the outcoupling grating and the first direction is an acute angle.

4. The near-eye display device according to claim 3, characterized in that: The angle formed by the side of the first slit facing the outcoupling grating and the first direction is in the range of 0° to 45°.

5. The near-eye display device according to claim 4, characterized in that: The angle formed by the side of the second slit facing the outcoupling grating and the first direction is in the range of 35° to 135°.

6. The near-eye display device according to claim 4, characterized in that: The projection of the outer contour of the folding grating on the optical waveguide is a trapezoid, and the top edge of the trapezoid is arranged close to the coupling grating; The bottom angle of the trapezoid facing the outcoupling grating is greater than the bottom angle of the trapezoid away from the outcoupling grating.

7. The near-eye display device according to claim 6, characterized in that: The bottom angle of the trapezoid facing the outcoupling grating is in the range of 80° to 100°.

8. The near-eye display device according to claim 7, characterized in that: The bottom angle of the trapezoid facing the outcoupling grating is a right angle.

9. The near-eye display device according to claim 6, characterized in that: The out-coupling grating includes a plurality of out-coupling partitions along the first direction, and the grating heights of the out-coupling partitions increase in sequence in the direction from the in-coupling grating to the out-coupling grating.

10. The near-eye display device according to claim 9, characterized in that: The outcoupling grating includes an outcoupling center; The near-eye display device also includes: an eye box structure located at the same end of the optical waveguide as the outcoupling grating; the eye box structure center is an orthographic projection of the optical waveguide, which does not coincide with the center of the orthographic projection of the outcoupling center on the optical waveguide, and is located on the side of the outcoupling center facing the folding grating.

11. The near-eye display device according to claim 10, wherein: In the direction from the coupling-in grating to the coupling-out grating, the plurality of coupling-out partitions include: a first coupling-out partition, a second coupling-out partition and a third coupling-out partition; The orthographic projection of the center of the eye box structure on the optical waveguide has an overlapping area with the orthographic projection of the second outcoupling partition on the optical waveguide, and has an overlapping area with the orthographic projection of the first outcoupling partition on the optical waveguide.

12. The near-eye display device according to claim 9, wherein: The grating heights of the same outcoupling subarea are the same.

13. The near-eye display device according to claim 4, characterized in that: The third slit extends along the second direction.

14. The near-eye display device according to claim 13, wherein: The coupling-in grating has a first grating vector, the vector direction of which is perpendicular to the direction of the first slit; the folding grating has a second grating vector, the vector direction of which is perpendicular to the direction of the second slit; the coupling-out grating has a third grating vector, the vector direction of which is perpendicular to the direction of the third slit; The sum of the first grating vector, the second grating vector and the third grating vector is zero.

15. A display device, characterized in that: Comprising a near-eye display device as described in any one of claims 1-14.

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