Optical waveguide with multiple turning regions and display device

Abstract

The application discloses a light waveguide with multiple turning regions and a display device. The light waveguide comprises an entrance pupil region, at least one first turning region for expanding the length of a light spot output by the entrance pupil region, at least one second turning region for expanding the width of the light spot output by the first turning region, and at least one exit pupil region. Light enters the entrance pupil region, is totally reflected into the first turning region, is totally reflected into the exit pupil region after being expanded in length and width by the first and second turning regions, and then enters the human eye from the exit pupil region. The display device comprises the light waveguide and an LBS light source. Therefore, by using the light waveguide with multiple turning regions in combination with the LBS light source, the size of the light spot is expanded in the lateral and longitudinal directions, the utilization rate of the LBS light source is improved, the LBS light source with a small volume and a small exit pupil is utilized, and a large expanded light source effect is achieved; the use experience of the display device is improved, and the display device is small in size, convenient to carry and store.

Description

Technical Field

[0001] This invention relates to the field of optical waveguide equipment, and in particular to an optical waveguide and display device having multiple turning regions. Background Technology

[0002] Optical systems are a crucial component of augmented reality (AR) devices. System considerations include light efficiency, ambient light transmittance, size, weight, and field of view (FOV). However, a perfect solution does not yet exist, and trade-offs must be struck between different parameters. When designing an AR optical system, several factors need to be considered: light efficiency (the proportion of light transmitted from the projector to the viewer's eye); ambient light transmittance; the size and weight of the optical system; and a larger FOV (field of view). One of the key technologies for augmented reality is the development of ultra-compact, lightweight, and low-power near-eye display solutions. Optical waveguides are currently the most promising optical solution in the AR field. Currently, DLP, LCOS, and micro LED light engines are commonly used in conjunction with waveguide displays, but their light efficiency is relatively low. Furthermore, these light engines have large exit pupil diameters, which correspondingly increases the entrance pupil area on the waveguide, resulting in a larger exit pupil size and a larger overall display device size. Therefore, improvements should be made to existing AR display devices to address the issues of poor light efficiency and large size. Summary of the Invention

[0003] In view of this, the present invention addresses the deficiencies of the existing technology, and its main objective is to provide an optical waveguide and display device with multiple transition regions. By employing an optical waveguide with multiple transition regions and combining it with an LBS light source, the light spot size is expanded in both the horizontal and vertical directions, effectively improving the utilization rate of the LBS light source, and achieving the effect of obtaining a large extended light source while utilizing a small-volume, small-exit-pupil, high-brightness LBS light source.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] An optical waveguide with multiple transition regions includes an entrance pupil region, at least one first transition region for laterally expanding the length of the light spot output from the entrance pupil region, at least one second transition region for longitudinally expanding the width of the light spot output from the first transition region, and at least one exit pupil region. Light enters through the entrance pupil region, undergoes total internal reflection into the first transition region, undergoes lateral expansion of the light spot length through the first transition region, undergoes total internal reflection into the second transition region, undergoes longitudinal expansion of the light spot width through the second transition region, undergoes total internal reflection into the exit pupil region, and then enters the human eye through the exit pupil region.

[0006] As a preferred embodiment, the optical waveguide includes two first inflection regions, two second inflection regions, and two exit pupil regions, which are symmetrically distributed around the entrance pupil region.

[0007] As a preferred embodiment, the diameter of the entrance pupil region is 1-2 mm.

[0008] As a preferred embodiment: the width of the first turning region is 1.1-3 times the diameter of the entrance pupil region; the width of the side of the first turning region away from the entrance pupil region is 1.5-3 times the width of the side closer to the entrance pupil region; and the length of the first turning region is 2-5 times the diameter of the entrance pupil region. The length of the second turning region is 0.6-0.8 times the length of the first turning region, and the width of the second turning region is 3-6 times its length. The width of the exit pupil region is 0.7-0.9 times the width of the second turning region, and the length of the exit pupil region is 1.5-2 times its width.

[0009] As a preferred embodiment, each region within the optical waveguide employs a diffraction grating, with different grating directions in the four regions, and the grating period and direction of the grating vector satisfying a vector sum equal to 0.

[0010] As a preferred embodiment: the diffraction efficiency of each region of the optical waveguide is different, the entrance pupil region has 1 efficiency zone; the first transition region has 3-8 efficiency zones, the second transition region has 4-10 efficiency zones, and the exit pupil region has 6-15 efficiency zones.

[0011] A display device includes the aforementioned optical waveguide and an LBS light source that provides light to the optical waveguide, the LBS light source being oriented toward the entrance pupil region of the optical waveguide.

[0012] As a preferred embodiment, the entrance pupil diameter of the optical waveguide is 1.1 to 1.3 times the exit pupil diameter of the LBS light source.

[0013] As a preferred embodiment, the LBS light source is one of the following: a red laser of 590-640nm, a green laser of 520-560nm, or a blue laser of 420-480nm, or any combination of these three colors of laser.

[0014] As a preferred embodiment, the field of view of the LBS light source is 20°-60°, and the center distance between the exit pupil of the LBS light source and the entrance pupil region of the optical waveguide is less than 1mm.

[0015] Compared with the prior art, the present invention has obvious advantages and beneficial effects. Specifically, as can be seen from the above technical solution, by using an optical waveguide with multiple turning regions and combining it with an LBS light source, the light spot size is expanded in the horizontal and vertical directions after passing through the small diameter entrance pupil region and the two turning regions, thereby expanding the usable area of ​​the incident light spot in multiple directions. This effectively improves the utilization rate of the LBS laser light source and achieves the effect of obtaining a large extended light source while utilizing a small-volume, small-exit pupil, and high-brightness LBS light source. This improves the user experience of near-eye display devices, and the overall size is small, making it convenient to carry and store.

[0016] To more clearly illustrate the structural features and effects of the present invention, a detailed description is provided below in conjunction with the accompanying drawings and specific embodiments. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the binocular integrated multi-turn region optical waveguide of the present invention;

[0018] Figure 2 This is a schematic diagram of the monocular integrated multi-turn region optical waveguide of the present invention;

[0019] Figure 3 This is a schematic diagram of the display device that combines the optical waveguide and LBS light source of the present invention.

[0020] Figure 4 This is a schematic diagram of the optical waveguide efficiency partitioning of the present invention;

[0021] Figure 5 This is a schematic diagram of the optical waveguide wave vector of the dual-eye optical waveguide of the present invention;

[0022] Figure 6 This is a schematic diagram of the waveguide wave vector of the single-eye waveguide of the present invention;

[0023] Figure 7 This is a schematic diagram of light propagation in the display device of the present invention.

[0024] Explanation of reference numerals in the attached diagram:

[0025] 10. Optical waveguide; 11. Entrance pupil region; 21, 22. First turning region; 31, 32. Second turning region; 41, 42. Exit pupil region; 50. LBS light source. Detailed Implementation

[0026] The present invention is as follows Figures 1 to 7 As shown, an optical waveguide and display device having multiple turning regions are disclosed, wherein:

[0027] The optical waveguide 10 includes an entrance pupil region, at least one first transition region for laterally extending the output spot length of the entrance pupil region, at least one second transition region for longitudinally extending the output spot width of the first transition region, and at least one exit pupil region; the diameter of the entrance pupil region of the waveguide is 1-2 mm, which is suitable for small exit pupil diameter light sources such as LBS light sources.

[0028] In this embodiment, the optical waveguide 10 can be in binocular or monocular form, as described in detail below;

[0029] like Figure 1 As shown, a binocular integrated multi-turn region optical waveguide 10 includes an entrance pupil region 11 located at the center of the long axis, a first turn region 21, a second turn region 31, and an exit pupil region 41 in the left part; a first turn region 22, a second turn region 32, and an exit pupil region 42 in the right part; and the first turn region 21, the second turn region 31, and the exit pupil region 41 in the left part and the first turn region 22, the second turn region 32, and the exit pupil region 42 in the right part are symmetrically distributed around the entrance pupil region 11.

[0030] like Figure 2 As shown, a monocular multi-turn region optical waveguide 10 includes an entrance pupil region 11 located at the transverse center, a first turn region 21, a second turn region 31, and an exit pupil region 41.

[0031] The width of the first transition region is 1.1-3 times the diameter of the entrance pupil region. The width W22 of the first transition regions 21 and 22 on the side away from the entrance pupil region 11 is 1.5-3 times the width W21 on the side closer to the entrance pupil region 11. The length L21 of the first transition regions 21 and 22 is 2-5 times the diameter of the entrance pupil region 11. The length L31 of the second transition regions 31 and 32 is 0.6-0.8 times the length L21 of the first transition regions 21 and 22. The width W31 of the second transition regions 31 and 32 is 3-6 times its length L31.

[0032] The width W41 of the exit pupil regions 41 and 42 is 0.7-0.9 times the width W31 of the second turning regions 31 and 32, and the length L41 of the exit pupil regions 41 and 42 is 1.5-2 times their width W41.

[0033] Each region within the optical waveguide 10 employs a diffraction grating. The grating directions in the four regions (entrance pupil region, first inflection region, second inflection region, and exit pupil region) are different, and the grating period and direction of the grating vector can satisfy the condition that the vector sum equals 0.

[0034] The optical waveguide 10 has different diffraction efficiencies in different regions. The entrance pupil region 11 has a smaller area and one diffraction efficiency zone. The diffraction efficiency of other regions increases along the wave vector direction, which can improve the brightness uniformity of the final displayed image. Specifically, the first transition regions 21 and 22 can be set with 3-8 diffraction efficiency zones, the second transition regions 31 and 32 can be set with 4-10 efficiency zones, and the exit pupil regions 41 and 42 can be set with 6-15 efficiency zones. Furthermore, all regions can also be set to have a continuous and gradual change in efficiency along their respective wave vector directions so that there are no obvious partition boundaries in appearance.

[0035] The display device is an AR near-eye display device, which includes the optical waveguide 10 and LBS light source 50 as described above. The diameter of the entrance pupil region 11 of the optical waveguide 10 is 1.1 to 1.3 times the exit pupil diameter of the LBS light source 50, allowing all the light source to be coupled into the entrance pupil region. It should be noted that the exit pupil diameter of the LBS light source 50 is 1-2 mm. Although its range is the same as the range of the diameter of the entrance pupil region 11, the exit pupil diameter of the LBS light source 50 is always smaller than the diameter of the entrance pupil region when the diameter of the entrance pupil region 11 is fixed. Furthermore, the width W21 (closer to the entrance pupil region) of the first transition regions 21 and 22 can be 1.1 to 1.3 times the exit pupil diameter of the LBS light source 50, allowing all the light from the entrance pupil region 11 to enter the first transition regions 21 and 22.

[0036] The LBS light source 50 is one of the following: a red laser of 590-640nm, a green laser of 520-560nm, or a blue laser of 420-480nm, or any combination of these three colors. The field of view of the light emitted by the LBS light source 50 is 20°-60°, and the center distance between the exit pupil of the LBS light source 50 and the center of the entrance pupil region 11 of the optical waveguide 10 is less than 1mm, enabling light emitted from the LBS light source 50 at various angles to enter the optical waveguide 10.

[0037] The light from the LBS light source 50 enters through the entrance pupil region 11, undergoes total internal reflection into the first turning regions 21 and 22, and after the light spot length is horizontally expanded through the first turning regions 21 and 22, it undergoes total internal reflection into the second turning regions 31 and 32. After the light spot width is vertically expanded through the second turning regions 31 and 32, it undergoes total internal reflection into the exit pupil regions 41 and 42, and then enters the human eye through the exit pupil regions 41 and 42.

[0038] like Figure 5 As shown, it corresponds to Figure 1The waveguide wave vector diagram shows that light of a specific wavelength can propagate along the left and right paths within the waveguide plate. The wave vectors of the input light (incident light) IN0 can exist in a region BOX0 of the wave vector space defined by the initial wave vectors kx and ky. Each corner of region BOX0 can represent the wave vector of the light at a corner point of the input image IMG0.

[0039] BND1 represents the first boundary used to satisfy the total internal reflection (TIR) ​​criterion in the waveguide plate of optical waveguide 10. BND2 represents the second boundary of the maximum wave vector in the waveguide plate. The maximum wave vector can be determined by the refractive index of the waveguide plate. Light can only propagate in the waveguide plate in waveguide form if the wave vector of the light is within the region ZONE1 between the first boundary BND1 and the second boundary BND2. If the wave vector of the light is outside the region ZONE1, the light may leak out of the waveguide plate or not propagate at all.

[0040] For a predetermined integer mij (i = 1, 2, 3, 4j = 1, 2, 3, 4), the grating period (d) and direction (θ) of the grating vector can satisfy the vector sum ΣmijVij = 0, that is, the propagation of the wave vector forms a closed path. Here, i is the region location identifier, such as 1 = entrance pupil region, 2 = first turning region, 3 = second turning region, 4 = exit pupil region; j is the path identifier, such as 1 = first path, 2 = second path (for example, the wave vector sum of the first side path is m11V11 + m21V21 + m31V31 + m41V41 = 0). The grating period (d) and grating direction (θ) of the diffraction grating can be determined by the grating vector V of the diffraction grating. The grating vector V can be defined as a vector having the direction of the diffracted lines perpendicular to the diffraction grating and an amplitude given by 2π / d, where d is the grating period (i.e., the fringe spacing).

[0041] Incident light IN0 enters the optical waveguide 10 from region BOX0 and propagates in the negative ky direction to the left of the grating V11. The wave vector of the propagating light B1a is in region BOX1a. Propagating light B1a in the V21 direction has its wave vector in region BOX2a. Propagating light B2a in the V31 direction has its wave vector in region BOX3a. Propagating light B3a in the V41 direction has its wave vector in region BOX4a, ultimately outputting image OUT1. Incident light IN0 enters the waveguide from region BOX0 and propagates in the positive ky direction to the right of the grating V12. The wave vector of the propagating light B1b is in region BOX1b. Propagating light B1b in the V22 direction has its wave vector in region BOX2b. Propagating light B2b in the V32 direction has its wave vector in region BOX3b. Propagating light B3b in the V42 direction has its wave vector in region BOX4b, ultimately outputting image OUT2.

[0042] like Figure 6 As shown, it corresponds to Figure 2 The waveguide wave vector diagram shows that the incident light IN0 enters the optical waveguide 10 from region BOX0 and propagates in the negative ky direction to the left of the grating V11. The wave vector of the propagating light B1a is in region BOX1a. Propagating light B1a in the V21 direction has its wave vector in region BOX2a. Propagating light B2a in the V31 direction has its wave vector in region BOX3a (coinciding with BOX1a). Propagating light B3a in the V41 direction has its wave vector in region BOX4a. The final output image is OUT1.

[0043] like Figure 7 As shown, the principle of light propagation in a display device is as follows:

[0044] The exit pupil of the LBS light source 50 is directly opposite the entrance pupil region 11 of the optical waveguide 10. The distance between the center of the exit pupil of the LBS light source 50 and the center of the entrance pupil region 11 of the optical waveguide 10 is less than 1 mm. The 1 mm diameter incident light IN0 emitted by the LBS light source 50 propagates to the grating on the entrance pupil region 11. The ±1st order diffracted light rays undergo total internal reflection on both sides of the optical waveguide 10 and propagate to the first turning regions 21 and 22, where the light spot length is laterally extended. The light rays reaching the first turning regions 21 and 22 then pass through... After diffraction by the grating, the light rays are propagated by total internal reflection within the waveguide to the second transition regions 31 and 32, respectively, which longitudinally expand the beam width. The beam size of the light rays that are totally reflected from the second transition regions 31 and 32 has the length of the first transition regions 21 and 22 and the width of the second transition regions 31 and 32. The light rays diffracted from the second transition regions 31 and 32 are propagated by total internal reflection within the waveguide to the exit pupil regions 41 and 42, respectively, and finally the light rays diffracted from the exit pupil regions 41 and 42 enter the user's line of sight.

[0045] The small entrance pupil waveguide of the display device has two turning regions. After the light source propagates through the two turning regions, the spot size is expanded in the horizontal and vertical directions respectively. While utilizing a small-volume, small-exit-pupil, high-brightness light source, a large extended light source can also be obtained.

[0046] Laser Beam Scanning (LBS) technology enhances light efficiency and increases the brightness of the display device in front of the eye. LBS scans a light source with a certain field of view in a very short time. The single-point light source has a small laser spot, which, combined with a light wave of the same diameter, is guided into the pupil area, and multiple turning areas are used to expand the light source. As a result, all-weather wearable AR smart glasses are characterized by small size, light weight, and high brightness, and can display high resolution, large FOV, and full-color images.

[0047] The key design feature of this invention is that by employing an optical waveguide with multiple turning regions and combining it with an LBS light source, the light spot size is expanded in both the horizontal and vertical directions after passing through the small-diameter entrance pupil region and the two turning regions. This multi-directional expansion of the usable area of ​​the incident light spot effectively improves the utilization rate of the LBS laser light source. It achieves the effect of obtaining a large extended light source while utilizing a small-volume, small-exit-pupil, high-brightness LBS light source, thus improving the user experience of near-eye display devices. Moreover, the overall size is small, making it convenient to carry and store.

[0048] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. An optical waveguide with multiple transition regions, characterized in that: The device includes an entrance pupil region, at least one first inflection region for laterally expanding the length of the light spot output from the entrance pupil region, at least one second inflection region for longitudinally expanding the width of the light spot output from the first inflection region, and at least one exit pupil region. Light enters through the entrance pupil region, undergoes total internal reflection into the first inflection region, is laterally expanded in length by the first inflection region, undergoes total internal reflection into the second inflection region, is longitudinally expanded in width by the second inflection region, and then undergoes total internal reflection into the exit pupil region, finally entering the human eye from the exit pupil region. The width of the first inflection region is 1.1-3 times the diameter of the entrance pupil region, the width of the side of the first inflection region furthest from the entrance pupil region is 1.5-3 times the width of the side closest to the entrance pupil region, and the length of the first inflection region is 2-5 times the diameter of the entrance pupil region. The length of the second inflection region is 0.6-0.8 times the length of the first inflection region, and the width of the second inflection region is 3-6 times its length. The width of the exit pupil region is 0.7-0.9 times the width of the second inflection region, and the length of the exit pupil region is 1.5-2 times its width.

2. The optical waveguide with multiple transition regions according to claim 1, characterized in that: It includes two first turning regions, two second turning regions, and two exit pupil regions, which are symmetrically distributed to the left and right of the entrance pupil region.

3. The optical waveguide with multiple transition regions according to claim 1, characterized in that: The diameter of the entrance pupil area is 1-2 mm.

4. The optical waveguide with multiple transition regions according to claim 1, characterized in that: Each region within the optical waveguide employs a diffraction grating, with different grating directions in the four regions. The grating period and direction of the grating vector satisfy the condition that the vector sum equals 0.

5. The optical waveguide with multiple transition regions according to claim 1, characterized in that: The optical waveguide has different diffraction efficiencies in different regions. The entrance pupil region has one efficiency zone; the first transition region has 3-8 efficiency zones; the second transition region has 4-10 efficiency zones; and the exit pupil region has 6-15 efficiency zones.

6. A display device, characterized in that: Includes an optical waveguide as described in any one of claims 1-5 and an LBS light source that provides light to the optical waveguide, the LBS light source being oriented toward the entrance pupil region of the optical waveguide.

7. The display device according to claim 6, characterized in that: The entrance pupil diameter of the optical waveguide is 1.1 to 1.3 times the exit pupil diameter of the LBS light source.

8. The display device according to claim 6, characterized in that: The LBS light source is one of the following: a red laser of 590-640nm, a green laser of 520-560nm, or a blue laser of 420-480nm, or any combination of these three colors of laser.

9. The display device according to claim 6, characterized in that: The field of view of the LBS light source is 20°-60°, and the center distance between the exit pupil of the LBS light source and the entrance pupil region of the optical waveguide is less than 1mm.

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