A display device

Abstract

This invention discloses a display device, including a projection optical engine and a diffractive waveguide. The diffractive waveguide includes a substrate, an entrance pupil element, a dilator element, and an exit pupil element disposed on the substrate. The projection optical engine is disposed opposite to the entrance pupil element and is used to project a plurality of projection beams into the entrance pupil element. The entrance pupil element includes an entrance pupil grating corresponding to each projection beam, which is used to input the projection beam to the corresponding dilator grating. The dilator element includes a plurality of dilator gratings corresponding to each entrance pupil grating, and the dilator gratings are located on the output optical path of the entrance pupil gratings, used to input the projection beam to the corresponding exit pupil element. Each exit pupil element includes a plurality of exit pupil gratings, and the exit pupil element is located in the overlapping area of ​​the output optical paths of the plurality of dilator gratings, used to couple the projection beams to form an output beam and output it. This invention can achieve the display of color patterns through a single diffractive waveguide, and has the characteristics of being lightweight and having clear colors.

Description

[0001] This invention is a divisional application filed with application number 202111265802.1 as the original application. Technical Field

[0002] This invention relates to the field of optical waveguide technology, and in particular to a display device. Background Technology

[0003] With the advancement of virtual imaging technology, users' demand for immersive experiences is increasing. In recent years, the development of VR (Virtual Reality) / AR (Augmented Reality) technologies has further enhanced the user's viewing experience. Moreover, VR / AR glasses based on head-mounted devices can free people's hands, reduce reliance on screens, and offer greater flexibility and interactivity, creating a better visual effect. For head-mounted devices, near-eye display is a key technology, and the imaging quality and thinness of the lenses are primary considerations in production and design. Near-eye display systems generally consist of near and far-light transmission systems. The image emitted from the image source is transmitted to the user's eye through the optical transmission system. Here, unlike VR's blocking of the external environment, AR requires a certain transmittance so that the wearer can see the external environment while viewing the image, achieving a combination of the external environment and the virtual image to achieve an augmented reality effect. Therefore, VR / AR imaging mainly relies on the optical transmission system. Currently, there are various solutions in the industry for achieving optical transmission, such as free-space optics, freeform surface optics, and display waveguides. Among them, optical waveguide technology has the characteristics of a large clear display area (eye box) and thinness, so it has become the mainstream display solution in virtual imaging.

[0004] Currently, AR glasses primarily utilize diffractive waveguide technology, such as Microsoft's HoloLens 1st and 2nd generations, and Magic Leap's AR glasses. Due to the low efficiency of light diffraction and the wavelength selection of gratings, most AR glasses employ 2-3 layers of diffractive waveguides to achieve color display. Each waveguide propagates a single color of light, and all colors of light converge at the exit pupil to form a color image. For example, patent application number 202010240060.6 uses 3 layers of lenses to achieve color image display. While this approach ensures the uniformity and brightness of the final image, its reliance on multiple diffractive waveguides increases the weight of the glasses, requiring users to bear a greater burden, and also increases manufacturing costs. Summary of the Invention

[0005] The technical problem to be solved by the present invention is that the AR display device with colorful images is too heavy for the user. In view of the shortcomings of the prior art, a display device is provided.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] A display device includes a projection optical engine and a diffractive waveguide;

[0008] The diffractive waveguide includes a substrate, an entrance pupil element, a pupil dilator element, and an exit pupil element disposed on the substrate;

[0009] The projection optical engine is disposed opposite to the entrance pupil element and is used to project a plurality of projection beams into the entrance pupil element, wherein each projection beam independently corresponds to a preset wavelength range;

[0010] The entrance pupil element includes an entrance pupil grating corresponding to each of the projection beams, the entrance pupil grating being used to input the projection beams to the corresponding dilator grating;

[0011] The pupil-expanding element includes a plurality of pupil-expanding gratings corresponding to each of the entrance pupil gratings, and the pupil-expanding gratings are located in the output optical path of the entrance pupil gratings, for inputting the projection beam to the corresponding exit pupil element;

[0012] Each of the exit pupil elements includes a plurality of exit pupil gratings. The exit pupil element is located in the overlapping area of ​​the output optical paths of the plurality of pupil gratings and is used to couple the projection beam to form an output beam and output it.

[0013] The display device, wherein the projection optical engine includes an optical engine housing, a display panel disposed within the optical engine housing, a first set of input light sources, a second set of input light sources, a first lens group, and a second lens group;

[0014] The wavelength range corresponding to the first group of input light sources is the wavelength range corresponding to blue light and green light;

[0015] The wavelength range corresponding to the second group of input light sources is the same as the wavelength range corresponding to red light;

[0016] The display panel is located at the rear focal plane of the first lens group and the front focal plane of the second lens group;

[0017] Each set of input light sources is located at the front focal plane of the first lens group;

[0018] Each input light source passes sequentially through the first lens group, the display panel, and the second lens group, and forms a projection beam corresponding to the input light source at the rear focal plane of the second lens group.

[0019] The display device includes a projection optical engine comprising a plurality of display optical engines, each of which includes a projection lens group and a light-emitting panel for emitting a projection beam, wherein each projection beam independently corresponds to a preset wavelength range, and the light-emitting panel is a Micro LED panel; the projection lens group is disposed opposite to the entrance pupil element;

[0020] Based on the projection lens group, the projection beam emitted by the light-emitting panel enters the entrance pupil element.

[0021] The display device, wherein the entrance pupil element includes an entrance pupil area, and a first entrance pupil grating and a second entrance pupil grating disposed on the surface of the entrance pupil area, wherein the first entrance pupil grating corresponds to the beam of the first group of input light sources, and the second entrance pupil grating corresponds to the beam of the second group of input light sources;

[0022] The pupil expanding element includes a first pupil expanding region with a first pupil expanding grating, a second pupil expanding region with a second pupil expanding grating, and a third pupil expanding region with a third pupil expanding grating and a fourth pupil expanding grating, wherein the output optical paths corresponding to the third pupil expanding grating and the fourth pupil expanding grating are different;

[0023] The exit pupil element includes a first exit pupil region provided with a first exit pupil grating and a third exit pupil grating, and a second exit pupil region provided with a second exit pupil grating and a fourth exit pupil grating;

[0024] Wherein, the first pupil expansion area and the second pupil expansion area are located on the output optical paths of the first entrance pupil grating in different directions;

[0025] The third pupil expansion area is located on the output optical path of the second entrance pupil grating;

[0026] The first exit pupil region is located in the overlapping area between the output optical path of the first pupil dilator grating and the output optical path of the third pupil dilator grating;

[0027] The second exit pupil region is located in the overlapping area between the output optical path of the second pupil grating and the output optical path of the fourth pupil grating.

[0028] In the display device, with the horizontal rightward direction as the positive direction, the angle θ11 between the grating direction of the first entrance pupil grating and the positive direction is 0°.

[0029] The angle θ12 between the grating direction of the second entrance pupil grating and the positive direction is -90°, and the grating period of the entrance pupil grating is 300~450nm;

[0030] The angle θ21 between the grating direction of the first pupil grating and the positive direction is -135°;

[0031] The angle θ22 between the grating direction of the second pupil grating and the positive direction is -45°;

[0032] The angle θ23 between the grating direction of the third pupil grating and the positive direction is 45°;

[0033] The angle θ23 between the grating direction and the positive direction of the fourth pupil grating is 135°, and the grating period of the pupil grating is 150~300 nm.

[0034] The angle θ31 between the grating direction of the first exit pupil grating and the positive direction is 90°, and the angle θ33 between the grating direction of the third exit pupil grating and the positive direction is 180°.

[0035] The angle between the grating direction of the second exit pupil grating and the positive direction is θ32=90°, the angle between the grating direction of the fourth exit pupil grating and the positive direction is θ34=0°, and the grating period of each exit pupil grating is 300~450 nm.

[0036] The display device wherein the length of the side of each pupil dilator closer to the pupil element is less than the length of the side farther from the pupil element;

[0037] The diameter of the entrance pupil in the entrance pupil region is 2.5~7 mm;

[0038] Both the first pupil dilation area and the second pupil dilation area are quadrilaterals with a maximum width of W1 and a maximum height of H1. The maximum width W1 is 5 to 10 times the diameter of the entrance pupil, and the maximum height H1 is 2 to 4 times the diameter of the entrance pupil.

[0039] The third pupil dilation zone is a quadrilateral with a maximum width of W2 and a maximum height of H2. The maximum width W2 is 2 to 4 times the diameter of the entrance pupil, and the maximum height H2 is 5 to 8 times the diameter of the entrance pupil.

[0040] Both the first exit pupil region and the second exit pupil region are quadrilaterals with a length of L and a width of W. The length L is 80% to 90% of the width W, and the width W is 80% to 90% of the maximum height value H2. The ratio of length L to width W is 16:9 or 4:3.

[0041] The display device, wherein the entrance pupil element includes a first entrance pupil area, a first entrance pupil grating disposed in the first entrance pupil area and corresponding to the beam of the first group of input light sources, a second entrance pupil area, a second entrance pupil grating disposed in the second entrance pupil area and corresponding to the beam of the second group of input light sources, and a third entrance pupil area, a third entrance pupil area disposed in the third entrance pupil area and corresponding to the beam of the second group of input light sources.

[0042] The pupil-expanding element includes a first pupil-expanding region with a first pupil-expanding grating, a second pupil-expanding region with a second pupil-expanding grating, a third pupil-expanding region with a third pupil-expanding grating, and a fourth pupil-expanding region with a fourth pupil-expanding grating.

[0043] The exit pupil element includes a first exit pupil region provided with a first exit pupil grating and a third exit pupil grating, and a second exit pupil region provided with a second exit pupil grating and a fourth exit pupil grating;

[0044] The first pupil expansion region and the second pupil expansion region are located on the output optical path opposite to the direction of the first entrance pupil grating;

[0045] The third pupil expansion area is located on the output optical path of the second entrance pupil grating, and the fourth pupil expansion area is located on the output optical path of the third entrance pupil grating;

[0046] The first exit pupil region is located in the overlapping area between the output optical path of the first pupil dilator grating and the output optical path of the third pupil dilator grating;

[0047] The second exit pupil region is located in the overlapping area between the output optical path of the second pupil grating and the output optical path of the fourth pupil grating.

[0048] In the display device, with the horizontal rightward direction as the positive direction, the angle θ11 between the grating direction of the first entrance pupil grating and the positive direction is 0°.

[0049] The angle θ13 between the grating direction of the second entrance pupil grating and the positive direction is -60°;

[0050] The angle between the grating direction of the third entrance pupil grating and the positive direction is θ14 = -120°, and the grating period of the entrance pupil grating is 300~450nm;

[0051] The angle θ21 between the grating direction of the first pupil grating and the positive direction is -135°;

[0052] The angle θ22 between the grating direction of the second pupil grating and the positive direction is -45°;

[0053] The angle θ23 between the grating direction of the third pupil grating and the positive direction is 60°;

[0054] The angle between the grating direction of the fourth pupil grating and the positive direction is θ24 = 120°, and the grating period of the pupil grating is 150~300nm;

[0055] The angle θ31 between the grating direction of the first exit pupil grating and the positive direction is 90°, and the angle θ33 between the grating direction of the third exit pupil grating and the positive direction is 180°.

[0056] The angle between the grating direction of the second exit pupil grating and the positive direction is θ32=90°, the angle between the grating direction of the fourth exit pupil grating and the positive direction is θ34=0°, and the grating period of the exit pupil grating is 300~450nm.

[0057] The display device wherein the length of the side of each pupil dilator closer to the pupil element is less than the length of the side farther from the pupil element;

[0058] The diameter of the entrance pupil in the entrance pupil region is 2.5~7 mm;

[0059] Both the first pupil dilation area and the second pupil dilation area are quadrilaterals with a maximum width of W1 and a maximum height of H1. The maximum width W1 is 5 to 10 times the diameter of the entrance pupil, and the maximum height H1 is 2 to 4 times the diameter of the entrance pupil.

[0060] Both the third and fourth pupil dilation areas are quadrilaterals with a maximum width of W3 and a maximum height of H3. The maximum width W3 is 4 to 7 times the diameter of the entrance pupil, and the maximum height H3 is 2 to 4 times the diameter of the entrance pupil.

[0061] Both the first exit pupil region and the second exit pupil region are quadrilaterals with a length of L and a width of W. The length L is 80% to 90% of the width W, and the width W is 3 to 6 times the diameter of the entrance pupil. The ratio of length L to width W is 16:9 or 4:3.

[0062] The display device, wherein a light filter assembly is provided at the outer edge of the pupil expanding element;

[0063] The light filtering assembly includes a first light filtering element and / or a second light filtering element, wherein the first light filtering element and / or the second light filtering element includes a light filtering element for filtering red light;

[0064] The first filter element is disposed in the pupil dilator element near the outer edge of the entrance pupil element;

[0065] The second filter element is disposed in the pupil dilator element near the outer edge of the exit pupil element.

[0066] The display device, wherein a light filter assembly is provided at the outer edge of the pupil expanding element;

[0067] The light filtering assembly includes a first light filtering element and / or a second light filtering element, wherein the first light filtering element and / or the second light filtering element includes a light filtering element for filtering red light;

[0068] The first filter element is disposed in the pupil dilator element near the outer edge of the entrance pupil element;

[0069] The second filter element is disposed in the pupil dilator element near the outer edge of the exit pupil element.

[0070] The display device wherein the first filter element is a filter strip with a thickness TH1 of 1.5 to 3 mm;

[0071] And / or the second filter element is a filter strip with a thickness TH2 of 1.5 to 3 mm.

[0072] The display device wherein the substrate is a butterfly binocular lens, and the entrance pupil element is disposed in the central region above the bridge of the nose of the butterfly binocular lens.

[0073] Beneficial Effects: Compared with existing technologies, this invention provides a display device comprising a projection optical engine and a diffractive waveguide. For each projection beam input from the projection optical engine, the diffractive waveguide sequentially performs entrance pupil, expansion pupil, and exit pupil operations via an entrance pupil grating, an expansion pupil grating, and an exit pupil grating. Each projection beam input from the projection optical engine independently corresponds to a specific wavelength range. At the final exit pupil, one exit pupil element carries several exit pupil gratings. Since the exit pupil element is located in the overlapping area of ​​the output optical paths of multiple expansion pupil gratings, projection beams corresponding to various wavelength ranges converge here to form an output beam. Through this method of color partitioning, setting multiple expansion pupil areas, and finally converging multiple colors for output, a single diffractive waveguide can achieve color image output, resulting in a smaller size and lighter weight. Furthermore, the design achieves more uniform color and higher energy utilization. Attached Figure Description

[0074] Figure 1 This is a schematic diagram of a projection optical engine provided by the present invention.

[0075] Figure 2 This is a schematic diagram illustrating the principle of color zoning in the focusless system provided by the present invention.

[0076] Figure 3 This is a schematic diagram of the structure of the second projection optical engine provided by the present invention.

[0077] Figure 4 A three-dimensional structural schematic diagram of the first diffractive waveguide and projection optical engine provided by the present invention.

[0078] Figure 5 The component distribution diagram of the first diffractive optical waveguide provided by the present invention.

[0079] Figure 6 This is a schematic diagram of the grating structure of the first diffractive waveguide provided by the present invention.

[0080] Figure 7A schematic diagram of the left-side path of the beam from the second set of input light sources provided by the present invention within the diffractive waveguide.

[0081] Figure 8 The component distribution diagram of the second type of diffractive waveguide provided by the present invention.

[0082] Figure 9 This is a schematic diagram of the grating structure of the second type of diffractive waveguide provided by the present invention.

[0083] Figure 10 This is a schematic diagram showing that the second entrance pupil grating and the third entrance pupil grating of the second diffractive waveguide provided by the present invention share a common entrance pupil region.

[0084] The meanings of the labels in the diagram are as follows:

[0085] 100, Diffractive waveguide; 110, Entrance pupil element; 111, First entrance pupil region; 112, Second entrance pupil region; 113, Third entrance pupil region; 121, First dilator region; 122, Second dilator region; 123, Third dilator region; 124, Fourth dilator region; 131, First exit pupil region; 132, Second exit pupil region; 141, Filter assembly disposed at the outer edge of the first dilator region; 142, Filter assembly disposed at the outer edge of the second dilator region; 300, Second projection optical engine; 301, First light source; 302, Second light source; 311, First lens group; 312, Second lens group; 320, Polarizing beam splitter; 330, Display panel; 340, Corner prism; 401-403, Light-emitting panel; 411-413, Projection lens group. Detailed Implementation

[0086] This invention provides a display device. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention.

[0087] For example, embodiments of the present invention can be applied to scenarios such as AR glasses. This display device is used to display preset patterns on the lenses of AR glasses.

[0088] It should be noted that the above application scenarios are shown only for the purpose of understanding the present invention, and the embodiments of the present invention are not limited in any way. On the contrary, the embodiments of the present invention can be applied to any applicable scenario.

[0089] The invention will be further explained below with reference to the accompanying drawings and the description of the embodiments.

[0090] This embodiment provides a display device, which includes a projection optical engine and a diffractive waveguide.

[0091] The projection optical engine contains the image to be displayed and a light source. The projection optical engine directs a beam of light carrying image information into a diffractive waveguide through the light source. In this embodiment, the image corresponding to the image information is named the source image, and the beam of light directed into the diffractive waveguide by the projection optical engine is called the projection beam.

[0092] The diffractive waveguide includes a substrate, an entrance pupil element 110 disposed on the substrate, a pupil expanding element, and an exit pupil element.

[0093] The substrate is the carrier that supports the entrance pupil element 110, the pupil dilator element, and the exit pupil element. In this embodiment, it is the substrate of AR glasses. The shape of the substrate can be circular, elliptical, or other shapes.

[0094] The projection engine is positioned opposite the entrance pupil element 110, and the projection beam emitted by the projection engine is projected into the entrance pupil element 110. To achieve the display of multiple color patterns, each projection beam independently corresponds to a preset wavelength range. Based on the principle of three primary colors, to achieve the display of multiple colors, three preset wavelength ranges can be used: blue light wavelength range (470 nm–475 nm), green light wavelength range (577–492 nm), and red light wavelength range (760 nm–622 nm). Correspondingly, the projection engine projects three projection beams, corresponding to the blue light wavelength range, green light wavelength range, and red light wavelength range, respectively. The number of projection beams can be more or less, for example, only corresponding to the red light wavelength range and blue light wavelength range, but the final displayed image will have limited colors. Therefore, to achieve a multi-color display, the projection beams must correspond to at least the blue light wavelength range, green light wavelength range, and red light wavelength range. Since the wavelength ranges of blue and green light are relatively close, and both are relatively narrow, their corresponding wavelength ranges can be combined into a blue-green light wavelength range. Therefore, the wavelength range corresponding to the projected beam includes at least the wavelength ranges corresponding to blue and green light, as well as the wavelength range corresponding to red light.

[0095] The entrance pupil element 110 includes an entrance pupil grating corresponding to each of the projected beams. Therefore, each incoming projected beam enters one of the entrance pupil gratings in the entrance pupil element 110. For each projected beam, after entering the entrance pupil element 110, the beam is propagated in different directions due to diffraction and reflection by the entrance pupil grating. The main function of the entrance pupil grating is to input the projected beam into the expanding pupil grating.

[0096] The pupil expanding element includes several pupil expanding gratings corresponding to each of the entrance pupil gratings, and the pupil expanding gratings are located in the output optical path of the entrance pupil gratings. Therefore, after the entrance pupil grating outputs the projected beam, the projected beam will enter the pupil expanding grating along the optical path. After entering the pupil expanding grating, the pupil expanding grating will output the input projected beam.

[0097] The exit pupil grating is located in the overlapping area of ​​the output optical paths of the multiple pupil-expanding gratings. Therefore, after the projection beam of the output pupil grating is emitted, it enters the exit pupil grating along the output optical path of the pupil-expanding grating. The exit pupil grating couples the input projection beam to form an output beam and outputs it. Since the exit pupil grating is not limited to the output optical path of the corresponding pupil-expanding grating, but also exists in the overlapping area of ​​multiple output optical paths, when the sum of the wavelength ranges corresponding to the projection beams input to the same exit pupil grating (i.e., the projection wavelength range) is the same as the sum of the wavelength ranges corresponding to the output beams of the same exit pupil grating (i.e., the projection wavelength range), it is equivalent to merging and outputting images of different colors from the same source image, ultimately forming a display image with multiple colors in the wearer's eyes.

[0098] The Benchmark implementation uses a single substrate to project images of multiple colors, reducing the weight of the entire display device, improving user comfort, and lowering production costs.

[0099] Furthermore, in terms of projection optical engine design, a projection optical engine can be composed of display optical engines that emit different wavelength ranges to display the same source image. For example... Figure 1 As shown, in the first projection optical engine provided in this embodiment, the projection optical engine comprises three display optical engines connected in parallel. Each display optical engine includes a light-emitting panel and a projection lens group. The light-emitting panel can be a Micro LED (Light-Emitting Diode) panel, which has the functions of displaying images and self-emitting light, thereby emitting a projection beam to the projection lens group. The wavelength range corresponding to the self-emission of each light-emitting panel is independent of each other, that is, each projection beam independently corresponds to a preset wavelength range. In this example, the wavelength range corresponding to light-emitting panel 401 is the blue light range, the wavelength range corresponding to light-emitting panel 402 is the green light range, and the wavelength range corresponding to light-emitting panel 403 is the red light range. The projection lens group is arranged opposite to the entrance pupil element. The projection beam emitted by the light-emitting panel passes through the projection lens group and enters the corresponding entrance pupil grating. For example, projection lens group 411 and projection lens group 412 are responsible for entering the entrance pupil grating corresponding to the blue and green light projection beams, respectively, and projection lens group 413 is responsible for entering the entrance pupil grating corresponding to the red light projection beam. If the beam entering the entrance pupil grating is an integrated beam of blue and green light, the projection lens group 411 and projection lens group 412 can be improved so that the blue and green light are mixed when or before the projection beam enters the entrance pupil grating.

[0100] However, this method results in a heavier projector engine, and the current display panel 330 is quite large. The entrance pupil element 110 occupies a large area on the substrate, and the area of ​​the exit pupil element is compressed, resulting in a smaller field of view (FOV).

[0101] In the second type of projection optical engine, a pupil-splitting optical engine is used to generate projection beams corresponding to different wavelength ranges based on the same display panel 330. The projection optical engine 300 includes an optical engine housing, a display panel 330 disposed within the optical engine housing, several input light sources, a first lens group 311, and a second lens group 312. The system used in this projection optical engine is a focusless system.

[0102] For ease of explanation, this embodiment uses a projected beam containing a beam from a first group of input light sources and a beam from a second group of input light sources as an example. The wavelength range corresponding to the beam from the first group of input light sources is the wavelength range corresponding to blue light and green light, and the wavelength range corresponding to the beam from the second group of input light sources is the wavelength range corresponding to red light.

[0103] The input light source can be composed of an integrated light source of red light, green light, and blue light. In this embodiment, the input light source includes a first light source 301 corresponding to the wavelength ranges of blue and green light, and a second light source 302 corresponding to the wavelength range of red light. Figure 2 As shown, the rear focal plane of the first lens group 311 coincides with the front focal plane of the second lens group 312, forming a focusless system. The first lens group 311 is a projection lens composed of several lenses, capable of uniformly projecting the input light source onto the display panel 330. The second lens group 312 is a projection lens composed of multiple lenses, capable of coupling light from the display panel 330 into the entrance pupil element.

[0104] The entrance pupil of the input light source is located at the front focal plane of the first lens group 311, and the exit pupil is located at the rear focal plane of the second lens group 312. In this system, since the input light source is located at the front focal plane of the first lens group 311, and the display panel 330 is located at the rear focal plane of the first lens group 311, each pixel of the image displayed on the display panel 330 can receive uniform illumination from each set of input light sources. Simultaneously, the source image displayed on the display panel 330 is located at the front focal plane of the second lens group 312. The second lens group 312 directly emits light to each pixel on the display panel 330, and a beam waist is formed at the rear focal plane of the second lens group 312, i.e., the exit pupil, which is the projection beam corresponding to the input light source. The light spot energy density is highest and the area is smallest at the exit pupil, and each point contains all the information of the projected image. Therefore, each set of input light sources passes sequentially through the first lens group 311, the display panel 330, and the second lens group 312, forming a projection beam corresponding to the input light source at the rear focal plane of the second lens group 312.

[0105] When the light from the input light source passes through the light spot on the exit pupil surface, blocking part of the light spot only reduces the brightness of the final projected image and does not affect the integrity of the pattern. Therefore, the projected beam carries the complete image information of the source image. Based on this characteristic, multiple aperture stops are set on the exit pupil surface of the second lens group 312. The aperture stops divide the light spot into several small blocks, which is equivalent to splitting the original image into the same number of sub-images as the aperture stops. Each sub-image contains the same image information as the source image. Then, each sub-image is coupled into a different entrance pupil grating, and the projected beam can be emitted in different directions. If the entrance pupil element 110 has multiple aperture stops, then for one input light source, multiple projected beams can be obtained.

[0106] At the same time, the input light source is split into several non-overlapping sub-light sources, such as... Figure 2 As shown, based on the symmetry of the afocal system, each sub-light source will form an image symmetrically on the exit pupil plane, which is the rear focal plane of the second lens group 312. The center of symmetry is the focal point of the overlapping focal plane between the first lens group 311 and the second lens group 312. The center-to-center distance between the object and the image is proportional to the center-to-center distance between the input light sources, and the magnification depends on the focal length of the second lens group 312. ,in The magnification is the perpendicular axis. This is the equivalent focal length of the second lens group 312. This is the equivalent focal length of the first lens group 311. Similarly, as with a single light source, multiple sub-light sources will form the waist of the projected beam on the exit pupil surface of the second lens group 312, and each light spot carries complete information of the original image.

[0107] Furthermore, if all wavelengths of the projection beam are directly projected onto the entrance pupil surface, half of the energy will be lost due to incorrect diffraction direction, thus reducing energy utilization to 25% and decreasing color uniformity and brightness. Therefore, this embodiment utilizes color partitioning and multiple expansion pupil areas to achieve more uniform image color, improve display effect, and increase energy utilization.

[0108] exist Figure 2 In this embodiment, the input light source set in the projection optical engine includes a red light source and a blue-green light source, which can be a light-emitting device such as Micro LED or laser. The display panel 330 used in this embodiment is a micro display panel 330, such as an LCOS (Liquid Crystal on Silicon) panel.

[0109] To input the projection beam into the entrance pupil element 110, the projection optical engine can directly position the entrance pupil element 110 at the rear focal plane of the second lens group 312. By adjusting the relative positions of the entrance pupil element 110 and the input light source, the projection beam formed by the input light source through the second lens group 312 directly enters the corresponding entrance pupil element 110. However, the input light source, the first lens group 311, and other components need to be spaced a certain distance apart to form the projection beam. Therefore, if the entrance pupil element 110 is directly positioned at the rear focal plane of the second lens group 312, the front of the display device will have a long protrusion, resulting in a large size, inconvenience in storage, and an unsightly appearance.

[0110] For this purpose, the projection optical engine also includes an adjustment lens assembly. The adjustment lens assembly is used to adjust the optical path of the input light source. By adjusting the optical path, the physical distance between the various components in the projection optical engine can be reduced, thereby reducing the size of the projection optical engine.

[0111] For example, the adjustment mirror includes a corner prism 340, which is positioned at or behind the back focal plane of the second lens group 312. The corner prism 340 functions as a light path deflector; by adjusting its shape, it can redirect the incident light beam at a certain angle. Taking an isosceles right-angled triangular corner prism 340 as an example, the inclined surface of the corner prism 340 is located at the back focal plane of the second lens group 312, thus redirecting the input projection beam by 90 degrees. Therefore, the long side of the projection engine can fit flush with the substrate, facilitating portability and storage.

[0112] For example, the adjusting mirror also includes a polarizing beam splitter 320, which can split the input light source into two mutually perpendicular beams. Figure 3 As shown, the plane containing the first lens group 311 is perpendicular to the plane containing the second lens group 312, and the plane containing the display panel 330 is perpendicular to the plane containing the first lens group 311. The polarizing beam splitter 320 is located on a vertical plane that bisects the angle between the first lens group 311 and the second lens group 312. Therefore, the input light source first passes through the first lens group 311 and then through the polarizing beam splitter 320. The polarizing beam splitter 320 splits the light from the input light source into two beams. One beam reaches the display panel 330. Since the display panel 330 is located on the back focal plane of the first lens group 311, the light reaching the display panel 330 then passes through the polarizing beam splitter 320 and enters the second lens group 312, finally forming a projection beam.

[0113] like Figure 4 As shown, the projection optical engine, including the corner prism 340 and the polarizing beam splitter 320, is small in size, and the display device based on the projection optical engine is more stable in structure and smaller in size, making it easier to carry and store.

[0114] If two independent circular lenses are used, each substrate requires a corresponding projection optical engine to achieve imaging for both lenses, which is costly. To achieve imaging for both lenses with a single projection optical engine, this embodiment uses a butterfly-shaped binocular lens substrate. Based on this shape, the entrance pupil element 110 is located in the central region above the nose bridge of the butterfly-shaped binocular lens. In this embodiment, this central region is located on the central axis of the waveguide, and the pupil dilator and exit pupil elements are distributed on the two wings of the butterfly. This method reduces the difficulty of binocular coupling and improves production efficiency.

[0115] Furthermore, since the projection beam has a divergence angle, in order to avoid light leakage and resulting in incomplete images at the exit pupil, the shape of the pupil-expanding element has been improved in this embodiment. The length of the side of all pupil-expanding elements closest to the entrance pupil element 110 is less than the length of the side furthest from the entrance pupil element 110.

[0116] This embodiment sets up two sets of input light sources. The beams of the first set of input light sources correspond to the wavelength ranges of blue and green light, and the beams of the second set of input light sources correspond to the wavelength range of red light. Taking these two sets of input light source beams as examples, this embodiment provides two specific diffraction waveguide schemes.

[0117] In the first type of diffractive waveguide, the entrance pupil element 110 includes an entrance pupil region, and a first entrance pupil grating and a second entrance pupil grating disposed on the surface of the entrance pupil region, wherein the first entrance pupil grating corresponds to the beam of the first group of input light sources, and the second entrance pupil grating corresponds to the beam of the second group of input light sources. Figure 5 As shown, the entrance pupil element 110 is disposed in the optical path direction of the projection optical engine. The entrance pupil element 110 is disposed above the nose bridge position in the diffraction waveguide. The entrance pupil element 110 is provided with diffraction gratings in two directions, distributed vertically.

[0118] like Figure 5 as well as Figure 6 As shown, the upper half of the entrance pupil grating is the first entrance pupil grating, with a grating direction of V11 and a grating period of d11. The first entrance pupil grating is responsible for propagating the light beam from the first set of input light sources to the first dilation pupil area 121 and the second dilation pupil area 122. Testing has shown that the diameter of the entrance pupil area, i.e., the entrance pupil diameter D, is best taken between 2.5 and 7 mm. The lower half of the entrance pupil grating is the second entrance pupil grating, with a grating direction of V12 and a grating period of d12. It is responsible for propagating the light beam from the second set of input light sources to the third dilation pupil area 123.

[0119] In this embodiment, with the horizontal to the right as the positive direction, the angle between V11 and the horizontal line is θ11=0°, and the angle between V12 and the horizontal line is θ12=-90°. The grating periods d11 and d12 of the first and second entrance pupil gratings are between 300 and 450 nm. Therefore, the grating direction of the first entrance pupil grating is perpendicular to the grating direction of the second entrance pupil grating, meaning that their diffraction directions are orthogonal. The positions of the subsequently placed pupil expanding elements are also orthogonal. Thus, this scheme can simultaneously accommodate the diffraction of entrance pupil light in two directions, improving the waveguide's field of view (FOV).

[0120] The pupil-expanding element includes a first pupil-expanding region 121 with a first pupil-expanding grating, a second pupil-expanding region 122 with a second pupil-expanding grating, and a third pupil-expanding region 123 with a third pupil-expanding grating and a fourth pupil-expanding grating. The first pupil-expanding region 121 and the second pupil-expanding region 122 are responsible for the propagation of the light beam from the first group of input light sources. The first pupil-expanding region 121 and the second pupil-expanding region 122 are located on output light paths with different directions from the first entrance pupil grating. That is, the first pupil-expanding region 121 and the second pupil-expanding region 122 are respectively on both sides of the entrance pupil region.

[0121] For example Figure 5 and Figure 6 In this embodiment, θ11 = 0°, therefore the output optical path of the first entrance pupil grating is the left and right sides of the entrance pupil element 110 on the plane of the substrate. In this embodiment, the pupil expansion area located on the left side of the entrance pupil element 110 is marked as the first pupil expansion area 121, and the pupil expansion area located on the right side of the entrance pupil element 110 is marked as the second pupil expansion area 122.

[0122] The first pupil expansion region 121 is provided with a first pupil expansion grating, the grating direction of which is V21, the angle with the horizontal line is θ21, and the grating period is d21. The second pupil expansion region 122 is provided with a second pupil expansion grating, the direction of which is V22, the angle with the horizontal line is θ22, and the grating period is d23. In this embodiment, θ21=-135°, θ22=-45°, and the grating periods d21 and d22 of the first and second pupil expansion gratings are taken in the range of 150~300 nm.

[0123] Simultaneously, the third pupil expansion region 123 is responsible for the propagation of the light beam from the second set of input light sources. The third pupil expansion region 123 is located on the output optical path of the second entrance pupil grating. The third pupil expansion region 123 is located on one side of the entrance pupil region and is in the same plane as the grating direction of the second entrance pupil grating. In this embodiment, θ12 = -90°, so the third pupil expansion region 123 is located below the entrance pupil region. The third pupil expansion region 123 is equipped with a third pupil expansion grating and a fourth pupil expansion grating. The grating direction of the third pupil expansion grating is V23, the angle with the horizontal line is θ23, and the grating period is d23. The grating direction of the fourth pupil expansion grating is V24, the angle with the horizontal line is θ24, and the grating period is d24. The output optical path of the third pupil expansion grating is different from that of the fourth pupil expansion grating. For example, in this embodiment, the output optical path corresponding to each grating is adjusted by setting different grating directions, θ23=45°, θ24=135°, and the grating periods d23 and d24 of the third and fourth pupil gratings are in the range of 150~300 nm.

[0124] The exit pupil element includes a first exit pupil region 131 with a first exit pupil grating and a third exit pupil grating, and a second exit pupil region 132 with a second exit pupil grating and a fourth exit pupil grating. The first exit pupil region 131 is located in the overlapping area of ​​the output optical path of the first dilating pupil region 121 and the output optical path of the third dilating pupil region 123, and the second exit pupil region 132 is located in the overlapping area of ​​the output optical path of the second dilating pupil region 122 and the output optical path of the fourth dilating pupil region 124.

[0125] For example Figure 5 and Figure 6 In this embodiment, the first exit pupil region 131 is located in the overlapping area of ​​the output optical path of the first pupil expanding grating and the output optical path of the third pupil expanding grating, that is, below the first pupil expanding region 121 and to the right of the third pupil expanding region 123. The first exit pupil region 131 is provided with a first exit pupil grating and a third exit pupil grating. The grating direction of the first exit pupil grating is V31, the angle with the horizontal line is θ31, and the grating period is d31. It is responsible for coupling the beam of the first group of input light sources out of the waveguide. The grating direction of the third exit pupil grating is V33, the angle with the horizontal line is θ33, and the grating period is d33. It is responsible for coupling the beam of the second group of input light sources out of the waveguide. In this embodiment, θ31=90°, θ33=180°.

[0126] The second exit pupil region 132 is located at the overlap of the optical paths of the second and third pupil dilation gratings, specifically below the second pupil dilation region 122 and to the left of the third pupil dilation region 123. The second exit pupil region 132 includes a second exit pupil grating and a fourth exit pupil grating. The second exit pupil grating has a grating direction of V32, an angle of θ33 with the horizontal line, and a grating period of d32. It is responsible for coupling blue and green light from the original image out of the waveguide. The fourth exit pupil grating has a grating direction of V34, an angle of θ34 with the horizontal line, and a grating period of d34. It is responsible for coupling red light from the image source out of the waveguide. In this embodiment, θ32 = 90° and θ34 = 0°.

[0127] Ultimately, the projection beams output from the first pupil expansion area 121 and the third pupil expansion area 123 couple in the first exit pupil area 131 to form an output beam and are output, forming a colored display image located on the left side of the substrate within the field of view. The projection beams output from the second pupil expansion area 122 and the third pupil expansion area 123 couple in the second exit pupil area 132 to form an output beam, forming a colored display image located on the right side of the substrate within the field of view.

[0128] In this scheme, the first and second pupil expansion regions 121 and 122 are both quadrilaterals with a maximum width of W1 and a maximum height of H1. The maximum width W1 can be 5 to 10 times the entrance pupil diameter D, and the maximum height can be 2 to 4 times the entrance pupil diameter D. The side closer to the entrance pupil region has the lowest height, and the side farther from the entrance pupil region has the highest height. The third pupil expansion region 123 is a quadrilateral with a maximum width of W3 and a maximum height of H3. The maximum width W3 can be 2 to 4 times the entrance pupil diameter D, and the maximum height H3 can be 5 to 8 times the entrance pupil diameter D. The side closer to the entrance pupil region has the lowest height, and the side farther from the entrance pupil region has the highest height.

[0129] A filter assembly is provided around the first pupil expansion area 121 and the second pupil expansion area 122 to filter red light. The filter assembly includes a first filter strip disposed at the outer edge of the first pupil expansion area 121 and a second filter strip disposed at the outer edge of the second pupil expansion area 122. The thickness of the first and second filter strips ranges from 1.5 to 3 mm.

[0130] Regarding the exit pupil area, in this embodiment, both the first exit pupil area 131 and the second exit pupil area 132 are quadrilaterals with a length of L and a width of W. To better conform to the specifications of the original image and the visual effect of the human eye, the length L can be 80% to 90% of W, and the width W can be 80% to 90% of H2, with L:W = 16:9 or L:W = 4:3. Furthermore, to closely approximate the interpupillary distance of the human eye, the center-to-center distance between the first exit pupil area 131 and the second exit pupil area 132 is 60 to 70 mm. This width value can be adjusted according to the wearer's requirements.

[0131] The grating periods d31, d32, d33, and d34 of the first, second, third, and fourth exit pupil gratings are between 300 and 450 nm.

[0132] Taking the beams of the first set of input light sources as an example, the propagation path of the light is described. When the beams of the first set of input light sources enter the first entrance pupil grating, diffraction occurs, forming ±1st order diffracted light (assuming the diffracted light on the right is +1st order light and the diffracted light on the left is -1st order light). Taking the +1st order diffracted light as an example, the +1st order diffracted light is coupled into the waveguide and propagates to the corresponding first dilated pupil region 121 through total internal reflection. This is the first entrance pupil light. After the first entrance pupil light comes into contact with the first dilated pupil grating, diffraction occurs, and the diffracted light undergoes total internal reflection towards the first exit pupil grating. This is the first dilated pupil light. After the first dilated pupil light comes into contact with the first exit pupil grating, diffraction occurs, and the diffracted light couples out of the waveguide and enters the human eye. This is the output beam corresponding to the beams of the first set of input light sources.

[0133] like Figure 7 As shown, taking the beam of the second set of input light sources corresponding to the red light range as an example, under the action of the projection optical engine, the beam of the second set of input light sources is coupled into the waveguide from the second entrance pupil grating. The beam of the second set of input light sources contacts the entrance pupil grating, producing diffraction. Diffraction produces +1st and -1st order beams. Since θ12 = -90°, it is assumed that the +1st order light propagates downward and the -1st order light propagates upward. The +1st order diffracted light is deflected towards the second exit pupil region 132 through the fourth pupil grating, and coupled out of the diffracted light waveguide under the action of the fourth exit pupil grating. However, some of the -1st order light will contact the first entrance pupil grating during propagation, thus deflecting towards the second pupil region 122. This part of crosstalk light will affect the uniformity of color. Therefore, in order to prevent red light interference and affect the imaging quality, in this embodiment, a filter component is provided on the outer edge of the pupil expanding element. Since the light causing crosstalk in this example is red light, the filter component is used to filter red light. The third pupil expansion zone 123 corresponds to red light and does not require a filter component.

[0134] When setting up the filter assembly, taking into account the propagation direction of the projected beam, the filter assembly may include a first filter element and / or a second filter element, wherein the first filter element is disposed in the pupil dilator near the outer edge of the entrance pupil element 110, and the second filter element is disposed in the pupil dilator near the outer edge of the exit pupil element.

[0135] For example Figure 5 and Figure 6As shown, the area of ​​the first pupil expansion region 121 near the first entrance pupil region 111 and the area of ​​the second pupil expansion region 122 near the second exit pupil region 132 are both equipped with filter components for filtering red light. It is worth noting that the filter components are mentioned here for filtering red light only because the beams of the first set of input light sources correspond to the wavelength ranges of blue and green light, and the beams of the second set of input light sources correspond to the wavelength range of red light. If the order of the wavelength ranges corresponding to the beams of the first and second sets of input light sources were reversed, the filter components would be used to filter blue and green light. This can be derived from the previously described configuration of the filter components.

[0136] In the second type of diffractive waveguide, such as Figure 8 and Figure 9 As shown, the entrance pupil element 110 includes three entrance pupil regions: a first entrance pupil region 111, a second entrance pupil region 112, and a third entrance pupil region 113, all located above the nose bridge of the diffraction waveguide. The entrance pupil element also includes a first entrance pupil grating disposed in the first entrance pupil region 111. The first entrance pupil grating corresponds to the beam of the first group of input light sources. The first entrance pupil region 111 is provided with the first entrance pupil grating, with a grating direction of V11, an angle θ11 with the horizontal line, and a grating period of d11. The first entrance pupil grating corresponds to the beam of the first group of input light sources and is used to guide beams corresponding to the blue-green light wavelength range into the pupil waveguide and transmit the beams of the first group of input light sources to the pupil dilator element.

[0137] The second entrance pupil region 112 is provided with a second entrance pupil grating. The grating direction is V13, the angle with the horizontal line is θ13, and the grating period is d13. The second entrance pupil grating corresponds to the beam of the second set of input light sources and is responsible for propagating the beam of the corresponding red light wavelength range to the pupil expansion element.

[0138] The third entrance pupil region 113 is provided with a third entrance pupil grating. The grating direction is V14, the angle with the horizontal line is θ14, and the grating period is d14. The third entrance pupil grating corresponds to the beam of the second group of input light sources and is responsible for propagating the beam of the corresponding red light wavelength range to the pupil expansion element.

[0139] In addition, such as Figure 10 As shown, the second entrance pupil region 112 and the third entrance pupil region 113 can overlap, as long as the gratings of the two do not overlap.

[0140] The pupil-expanding element includes a first pupil-expanding region 121 with a first pupil-expanding grating, a second pupil-expanding region 122 with a second pupil-expanding grating, a third pupil-expanding region 123 with a third pupil-expanding grating, and a fourth pupil-expanding region 124 with a fourth pupil-expanding grating.

[0141] The first pupil expansion region 121 is located in one optical path direction of the first entrance pupil region 111, for example, to the right of the first entrance pupil region 111. The first pupil expansion region 121 is provided with a first pupil expansion grating, the grating direction is V21, the angle with the horizontal line is θ21, and the grating period is d21.

[0142] The second pupil expansion region 122 is located in another optical path direction of the first entrance pupil region 111, for example, to the left of the first entrance pupil region 111. A second pupil expansion grating is provided therein, with the grating direction being V22 and the angle between it and the horizontal line being θ22, and the grating period being d22. That is, the first pupil expansion region 121 and the second pupil expansion region 122 are located on output optical paths with different directions from the first entrance pupil grating.

[0143] The third pupil expansion region 123 is located on the output optical path of the second entrance pupil grating. The third pupil expansion region 123 is provided with a third pupil expansion grating with a grating direction of V23, an angle of θ23 with the horizontal line, and a grating period of d23.

[0144] The fourth pupil expansion region 124 is located on the output optical path of the third entrance pupil grating. The fourth pupil expansion region 124 is provided with a fourth pupil expansion grating with a grating direction of V24, an angle of θ24 with the horizontal line, and a grating period of d24.

[0145] The first exit pupil region 131 is located at the intersection of the optical paths of the first dilation pupil region 121 and the third dilation pupil region 123, for example, below the first dilation pupil region 121 and to the right of the third dilation pupil region 123. The first exit pupil region 131 is provided with a first exit pupil grating and a third exit pupil grating.

[0146] The exit pupil element includes a first exit pupil region 131 with a first exit pupil grating and a third exit pupil grating, and a second exit pupil region 132 with a second exit pupil grating and a fourth exit pupil grating.

[0147] The first exit pupil region 131 is located in the overlapping area of ​​the output optical path of the first pupil grating and the output optical path of the third pupil grating. The grating direction of the first exit pupil grating is V31, the angle with the horizontal line is θ31, and the grating period is d31. It is responsible for coupling the beam of the first group of input light sources out of the waveguide.

[0148] The third exit pupil grating has a grating direction of V33 and an angle of θ33 with the horizontal line. The grating period is d33. It is responsible for coupling the beams from the second set of input light sources out of the waveguide.

[0149] The second exit pupil region 132 is located in the overlapping area of ​​the output optical path of the second pupil grating and the output optical path of the fourth pupil grating, for example, it is located below the second pupil region 122 and to the left of the fourth pupil region 124. The second exit pupil region 132 is provided with a second exit pupil grating and a fourth exit pupil grating. The grating direction of the second exit pupil grating is V32, the angle with the horizontal line is θ32, and the grating period is d32. It is responsible for coupling the beam of the first group of input light sources out of the waveguide.

[0150] The fourth exit pupil grating has a grating direction of V34 and an angle of θ34 with the horizontal line. The grating period is d34. It is responsible for coupling the beams from the second set of input light sources out of the waveguide.

[0151] Therefore, for each exit pupil region, the beams from the first set of input light sources and the second set of input light sources can be coupled to form an output beam and coupled out of the waveguide, ultimately forming a color image within the viewer's field of vision. Since the propagation path of the light is similar to that of the first type of diffractive waveguide, it will not be described in detail here.

[0152] The diameter D of the entrance pupil region is between 2.5 and 7 mm, and the grating periods d11 and d12 of the first and second entrance pupil gratings are between 300 and 450 nm.

[0153] In this embodiment, the specific parameters of the included angles are θ11=0°, θ13=-60°, θ14=-120°, θ21=-135°, θ22=-45°, θ23=60°, θ24=120°, θ31=90°, θ33=180°, θ32=90°, and θ34=0°.

[0154] In addition, since the entrance pupil beam has a divergence angle, in order to avoid light leakage and resulting in incomplete images at the exit pupil, the shape of the first pupil expansion region 121 and the second pupil expansion region 122 has been improved, as in the previous waveguide.

[0155] The first pupil expansion region 121 and the second pupil expansion region 122 are quadrilaterals with a maximum width value of W1 and a maximum height value of H1. The maximum width value W1 can be 5 to 10 times the entrance pupil diameter D, and the maximum height value can be 2 to 4 times the entrance pupil diameter D. The side closer to the entrance pupil region has the lowest height, and the side farther away from the entrance pupil region has the highest height. The grating periods d21 and d22 of the first pupil expansion grating and the second pupil expansion grating are between 150 and 300 nm.

[0156] The third and fourth pupil expansion regions 123 and 124 are quadrilaterals with a maximum width value of W3 and a maximum height value of H3, located on both sides of the waveguide nose bridge in a "figure-eight" distribution. The distance between the two pupil expansion regions is shortest on the side facing the entrance pupil and longest on the side furthest from the entrance pupil. The maximum width value W3 can be 4 to 7 times the entrance pupil diameter D, and the maximum height value H3 can be 2 to 4 times the entrance pupil diameter D. The height is lowest on the side closer to the entrance pupil and highest on the side furthest from it. The grating periods d23 and d24 of the third and fourth pupil expansion gratings range from 150 to 300 nm.

[0157] The outer edges of the first pupil expansion area 121 and the second pupil expansion area 122 are provided with filter components to filter stray light. When setting the filter components, considering the propagation direction of the projected beam, the filter components may include a first filter element and / or a second filter element, wherein the first filter element is disposed in the pupil expansion element near the outer edge of the entrance pupil element 110, and the second filter element is disposed in the pupil expansion element near the outer edge of the exit pupil element.

[0158] The filtering assembly includes a first filter band for filtering light in the first pupil expansion area 121 and a second filter band for filtering red light in the second pupil expansion area 122. The first filter band is located around the first pupil expansion area 121, and the second filter band is located around the second pupil expansion area 122. The first filter band is located at the outer edge of the first pupil expansion area 121, and its thickness TH1 is between 1.5 and 3 mm. The second filter band 142 is located at the outer edge of the second pupil expansion area 122, and its thickness TH2 is between 1.5 and 3 mm.

[0159] The first exit pupil region 131 and the second exit pupil region 132 are both quadrilaterals with a length of L and a width of W. The length L can be 80% to 90% of the width W, and the width W can be 3 to 6 times the entrance pupil diameter D. The ratio of L:W is 16:9 or L:W is 4:3. The grating periods d31, d32, d33 and d34 of the first exit pupil grating, the second exit pupil grating, the third exit pupil grating and the fourth exit pupil grating are between 300 and 450 nm.

[0160] The center-to-center distance between the first exit pupil area 131 and the second exit pupil area 132 is 60-70 mm, which is the same as the interpupillary distance of the human eye and can be adjusted according to the wearer's requirements.

Claims

1. A display device, comprising a projection optical engine and a diffractive waveguide; The diffractive waveguide includes a substrate, an entrance pupil element, a pupil dilator element, and an exit pupil element disposed on the substrate; The projection optical engine is disposed opposite to the entrance pupil element and is used to direct a plurality of projection beams into the entrance pupil element, wherein... Each of the projected beams independently corresponds to a preset wavelength range; The projection optical engine includes an optical engine housing, a display panel disposed within the optical engine housing, a first set of input light sources, a second set of input light sources, a first lens group, and a second lens group; The display panel is located at the rear focal plane of the first lens group and the front focal plane of the second lens group; Each set of input light sources is located at the front focal plane of the first lens group; Each set of input light sources passes sequentially through the first lens group, the display panel, and the second lens group, and forms a projection beam corresponding to the input light source on the rear focal plane of the second lens group; The exit pupil element is used to couple the projection beam from the pupil dilator element to form an output beam and output it; The entrance pupil element includes a first entrance pupil region, a first entrance pupil grating disposed in the first entrance pupil region and corresponding to the beam of the first group of light sources, a second entrance pupil region, a second entrance pupil grating disposed in the second entrance pupil region and corresponding to the beam of the second group of light sources, a third entrance pupil region, and a third entrance pupil grating disposed in the third entrance pupil region and corresponding to the beam of the second group of light sources. The pupil-expanding element includes a first pupil-expanding region with a first pupil-expanding grating, a second pupil-expanding region with a second pupil-expanding grating, a third pupil-expanding region with a third pupil-expanding grating, and a fourth pupil-expanding region with a fourth pupil-expanding grating. The exit pupil element includes a first exit pupil region provided with a first exit pupil grating and a third exit pupil grating, and a second exit pupil region provided with a second exit pupil grating and a fourth exit pupil grating; Wherein, the first pupil expansion area and the second pupil expansion area are located on the output optical paths of the first entrance pupil grating in different directions; The third pupil expansion area is located on the output optical path of the second entrance pupil grating, and the fourth pupil expansion area is located on the output optical path of the third entrance pupil grating; The first exit pupil region is located in the overlapping area between the output optical path of the first pupil dilator grating and the output optical path of the third pupil dilator grating; The second exit pupil region is located in the overlapping area between the output optical path of the second pupil dilator and the output optical path of the fourth pupil dilator; The light beam from the first set of light sources is incident on the first entrance pupil grating and propagates to the second dilating pupil grating and the third dilating pupil grating; The light beam from the second set of light sources is incident on the second entrance pupil grating and propagates to the third dilating pupil grating; and is incident on the third entrance pupil grating and propagates to the fourth dilating pupil grating.

2. The display device according to claim 1, characterized in that, The wavelength range corresponding to the first group of input light sources is the wavelength range corresponding to blue light and green light; The wavelength range corresponding to the second set of input light sources is the same as the wavelength range corresponding to red light.

3. The display device according to claim 1, characterized in that, With the horizontal direction to the right as the positive direction, the angle θ11 between the grating direction of the first entrance pupil grating and the positive direction is 0°. The angle θ13 between the grating direction of the second entrance pupil grating and the positive direction is -60°; The angle between the grating direction of the third entrance pupil grating and the positive direction is θ14 = -120°, and the grating period of the entrance pupil grating is 300~450nm; The angle θ21 between the grating direction of the first pupil grating and the positive direction is -135°; The angle θ22 between the grating direction of the second pupil grating and the positive direction is -45°; The angle between the grating direction of the third pupil grating and the positive direction is θ23=60°, and the grating period of all pupil gratings is 150~300 nm; The angle θ24 between the grating direction of the fourth pupil grating and the positive direction is 120°; The angle θ31 between the grating direction of the first exit pupil grating and the positive direction is 90°, and the angle θ33 between the grating direction of the third exit pupil grating and the positive direction is 180°. The angle between the grating direction of the second exit pupil grating and the positive direction is θ32=90°, the angle between the grating direction of the fourth exit pupil grating and the positive direction is θ34=0°, and the grating period of all exit pupil gratings is 300~450 nm.

4. The display device according to claim 3, characterized in that, In each of the pupil-dilating elements, the length of the side closer to the entrance pupil element is less than the length of the side farther from the entrance pupil element; The entrance pupil diameter of the entrance pupil region is 2.5~7 mm; Both the first pupil dilation area and the second pupil dilation area are quadrilaterals with a maximum width of W1 and a maximum height of H1, wherein the maximum height H1 is 2 to 4 times the diameter of the entrance pupil; Both the third and fourth pupil dilation areas are quadrilaterals with a maximum width of W3 and a maximum height of H3. The maximum width W3 is 4 to 7 times the diameter of the entrance pupil, and the maximum height H3 is 2 to 4 times the diameter of the entrance pupil. Both the first exit pupil region and the second exit pupil region are quadrilaterals with a length of L and a width of W. The length L is 80% to 90% of the width W, and the width W is 3 to 6 times the diameter of the entrance pupil. The ratio of length L to width W is 16:9 or 4:

3.

5. The display device according to any one of claims 1 to 4, characterized in that, The outer edge of the pupil-expanding element is provided with a light-filtering component; The light filtering assembly includes a first light filtering element and / or a second light filtering element, wherein the first light filtering element and / or the second light filtering element includes a light filtering element for filtering red light; The first filter element is disposed in the pupil dilator element near the outer edge of the entrance pupil element; The second filter element is disposed in the pupil dilator element near the outer edge of the exit pupil element.

6. The display device according to claim 5, characterized in that, The first filter element is a filter strip with a thickness TH1 of 1.5 to 3 mm; And / or the second filter element is a filter strip with a thickness TH2 of 1.5 to 3 mm.

7. The display device according to claim 1, characterized in that, The substrate is a butterfly-shaped binocular lens, and the entrance pupil element is located in the central area above the bridge of the nose of the butterfly-shaped binocular lens.

Images