Waveguide display avoiding color crosstalk
By using a two-layer waveguide plate structure and an incident coupler design, the color crosstalk problem in waveguide displays was solved, improving image brightness and color uniformity, reducing weight, and simplifying the structure.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CETHIK GRP
- Filing Date
- 2022-09-15
- Publication Date
- 2026-07-03
AI Technical Summary
In the prior art, waveguide displays with multilayer waveguide plates suffer from color crosstalk, resulting in poor brightness and color uniformity of the output image. Existing solutions, such as using polarizing devices or light-absorbing materials, are ineffective or reduce light intensity.
A two-layer waveguide structure is adopted, which uses the diffraction order and zero-order diffraction order of the incident coupler to couple light of different wavelengths into each waveguide and transmit them through total internal reflection in each waveguide. The crosstalk of light is avoided by extending the coupler, and transparent high refractive index glass material is used.
It improves the brightness and color uniformity of the output image, while reducing the weight of the waveguide display. It eliminates the need for polarization devices and light-absorbing materials, and achieves effective isolation between light rays.
Smart Images
Figure CN115629439B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of optics, and specifically relates to a waveguide display that avoids color crosstalk. Background Technology
[0002] To increase the maximum field of view (FOV) of AR diffractive waveguides, existing technologies employ a method of stacking multiple waveguide layers, such as three layers, with each layer carrying one light ray to achieve transmission of multiple rays in a large field of view. However, different light rays are transmitted within each waveguide layer, leading to color crosstalk between them and resulting in poor brightness and color uniformity in the output image.
[0003] Existing patent EP2887128B1 uses polarization devices between different waveguide plates to convert different light rays incident on different waveguide layers into different polarization directions, so that the incident light rays corresponding to adjacent waveguide layers have orthogonal polarization states. It reduces color crosstalk by utilizing the polarization sensitivity of the incident coupling devices of different waveguide plates. However, since the incident coupler is not very sensitive to polarization, the effect of preventing crosstalk is much lower than expected. Patent US20220229290A1 uses different light-absorbing materials added to different waveguide plates to absorb other light rays that crosstalk to the waveguide plates. However, adding light-absorbing materials to the waveguide plates will reduce the transparency of the waveguide plates, greatly reducing the intensity of light entering the human eye. Summary of the Invention
[0004] The purpose of this invention is to address the problems mentioned in the background art by proposing a waveguide display that avoids color crosstalk.
[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0006] This invention proposes a waveguide display that avoids color crosstalk, comprising a micro-optical engine. The waveguide display further includes a first incident coupler, a second incident coupler, a first waveguide plate, a second waveguide plate, a first extension coupler, a second extension coupler, a first output coupler, and a second output coupler, wherein:
[0007] The first waveguide plate and the second waveguide plate are arranged side by side in sequence.
[0008] The first incident coupler, the first extended coupler, and the first output coupler are attached to the first waveguide plate and are all located on the side away from the second waveguide plate. The second incident coupler, the second extended coupler, and the second output coupler are attached to the second waveguide plate and are all located on the side closer to the second waveguide plate.
[0009] The micro-optical engine outputs a first wavelength light, a second wavelength light, and a third wavelength light. The field of view is equal for each wavelength light. Each incident coupler uses the first diffraction order and the zeroth diffraction order to divide the second wavelength light into a field of view light and a field of view light.
[0010] The first incident coupler uses the first diffraction order to couple both the first wavelength light and the a-field-of-view light into the first waveguide plate. After total internal reflection by the first waveguide plate, the light is extended by the first extension coupler and then coupled out to the human eye from the first output coupler. The first incident coupler uses the zeroth order diffraction order to couple both the b-field-of-view light and the third wavelength light into the second waveguide plate. After total internal reflection by the second waveguide plate, the light is extended by the second extension coupler and then coupled out to the human eye from the second output coupler, thus achieving uniformity of color and brightness in the coupled image.
[0011] Preferably, each waveguide plate is made of transparent high-refractive-index glass with a refractive index of 1.7 to 2.0.
[0012] Preferably, the wavelength of the first wavelength light is 440nm to 460nm, the wavelength of the second wavelength light is 520nm to 540nm, and the wavelength of the third wavelength light is 615nm to 635nm.
[0013] Preferably, each incident coupler is a one-dimensional periodic structure, and the period of each incident coupler is 200nm to 500nm.
[0014] Preferably, the diagonal field of view of the micro-optical machine is 28° to 50°.
[0015] Preferably, each coupler is a surface relief grating or a volume holographic grating.
[0016] Preferably, the incident coupler, extension coupler, and output coupler on each waveguide plate are arranged in an L-shape.
[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0018] 1. This waveguide display uses corresponding incident couplers on each waveguide plate. The first diffraction order of the first incident coupler allows the light of the first wavelength and the light of the a-field angle to be completely coupled into the first waveguide plate for total internal reflection transmission. The first diffraction order of the second incident coupler allows the light of the b-field angle and the third wavelength to be completely coupled into the second waveguide plate for total internal reflection transmission. Through the expansion couplers, crosstalk between the first wavelength and the third wavelength light is prevented, thereby improving the brightness and color uniformity of the output image.
[0019] 2. Compared with the prior art, this waveguide display reduces the three-layer waveguide plate to two-layer waveguide plate, which reduces the weight of the entire waveguide display. At the same time, it can prevent crosstalk between light without the use of polarization devices and light-absorbing materials. Attached Figure Description
[0020] Figure 1 This is a schematic diagram of the waveguide display structure for avoiding color crosstalk according to the present invention;
[0021] Figure 2 This is a first-mode distribution diagram of each coupler on each waveguide plate of the present invention;
[0022] Figure 3 This is a second-mode distribution diagram of each coupler on each waveguide plate of the present invention;
[0023] Figure 4 This is a K-Layout diagram of the first waveguide plate of the present invention;
[0024] Figure 5 This is the K-Layout diagram of the second waveguide plate of the present invention.
[0025] Explanation of reference numerals in the attached figures: 1. Micro-optical engine; 2. First incident coupler; 3. Second incident coupler; 4. First waveguide plate; 5. Second waveguide plate; 6. First output coupler; 7. Second output coupler; 8. Human eye. Detailed Implementation
[0026] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0027] It should be noted that when a component is referred to as being "connected" to another component, it can be directly connected to the other component or there may be an intervening component. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to limit the application.
[0028] like Figure 1-5 As shown, a waveguide display that avoids color crosstalk includes a micro-optomechanical system 1. The waveguide display also includes a first incident coupler 2, a second incident coupler 3, a first waveguide plate 4, a second waveguide plate 5, a first extension coupler, a second extension coupler, a first output coupler 6, and a second output coupler 7, wherein:
[0029] The first waveguide plate 4 and the second waveguide plate 5 are arranged side by side in sequence.
[0030] The first incident coupler 2, the first extended coupler, and the first output coupler 6 are attached to the first waveguide plate 4 and are all located on the side away from the second waveguide plate 4. The second incident coupler 3, the second extended coupler, and the second output coupler 7 are attached to the second waveguide plate 5 and are all located on the side close to the second waveguide plate 5.
[0031] Micro-optical engine 1 outputs a first wavelength light, a second wavelength light, and a third wavelength light. The field of view is equal for each wavelength light. Each incident coupler uses the first diffraction order and the zeroth diffraction order to divide the second wavelength light into a field of view light and a field of view light.
[0032] The first incident coupler 2 uses the first diffraction order to couple the first wavelength light and the a field-of-view light into the first waveguide plate 4. After total internal reflection by the first waveguide plate 4, the light is extended by the first extension coupler and then coupled out from the first output coupler 6 to the human eye 8. The first incident coupler 2 uses the zeroth order diffraction order to couple the b field-of-view light and the third wavelength light through the first waveguide plate 4 to the second incident coupler 3. The second incident coupler 3 uses the first diffraction order to couple the b field-of-view light and the third wavelength light into the second waveguide plate 5. After total internal reflection by the second waveguide plate 5, the light is extended by the second extension coupler and then coupled out from the second output coupler 7 to the human eye 8, thus achieving uniformity of color and brightness in the coupled image.
[0033] Specifically, with Figure 1 For example, taking the position of each input coupler as the left and the position of each output coupler as the right, the micro-optical engine 1, the first incident coupler 2, the first waveguide plate 4, the second incident coupler 3, and the second waveguide plate 5 are arranged sequentially from top to bottom. The first incident coupler 2 and the second incident coupler 3 are installed on the upper side of the first waveguide plate 4 and the second waveguide plate 5 respectively. The first extension coupler and the second extension coupler are installed on the upper side of the first waveguide plate 4 and the second waveguide plate 5 respectively. The first output coupler 6 and the second output coupler 7 are installed on the upper side of the first waveguide plate 4 and the second waveguide plate 5 respectively. Each coupler is pressed onto the corresponding waveguide plate by imprinting. Taking the up-down direction as the Z-axis and the left-right direction as the X-axis, the direction perpendicular to the X-axis and the Z-axis respectively is the Y-axis (i.e., the front-back direction). The angle between the micro-optical engine 1 and the X-axis or Y-axis is in the range of -10° to 10°. Figure 1The dashed arrows in the diagram represent the transmission of light rays at field angle a, and the solid arrows represent the transmission of light rays at field angle b. The first incident coupler 2 uses the first diffraction order to couple the light rays at the first wavelength and field angle a into the first waveguide plate 4 for total internal reflection. The first incident coupler 2 also uses the zero diffraction order to allow the light rays at field angle b and the third wavelength to pass through the first waveguide plate 4 to the second incident coupler 3. The second incident coupler 3 uses the first diffraction order to couple the light rays at field angle b and the third wavelength into the second waveguide plate 5 for total internal reflection. Then, through each extension coupler, the light rays at the corresponding field angles are extended and transmitted, optimizing the light at each field angle and preventing crosstalk between different light rays in each waveguide plate. Finally, through each output coupler, the light rays of each wavelength are coupled out to the human eye 8, achieving uniformity in brightness and color of the coupled image. In order for the field of view angles coupled from the a-field angle ray and the b-field angle ray to be the complete field of view angle under the second wavelength ray, the field of view angles coupled from the a-field angle ray and the b-field angle ray are both greater than half of the complete field of view angle of the second wavelength ray.
[0034] Specifically, this ensures that the second wavelength of light in the coupled image has a complete field of view.
[0035] In one embodiment, each waveguide plate is a transparent high-refractive-index glass with a refractive index of 1.7 to 2.0.
[0036] In one embodiment, the wavelength of the first wavelength light is 440nm to 460nm, the wavelength of the second wavelength light is 520nm to 540nm, and the wavelength of the third wavelength light is 615nm to 635nm.
[0037] In one embodiment, each incident coupler is a one-dimensional periodic structure, and the period of each incident coupler is 200nm to 500nm.
[0038] In one embodiment, the diagonal field of view of the micro-optomechanical system 1 is 28° to 50°.
[0039] In one embodiment, each coupler is a surface relief grating or a volume holographic grating.
[0040] In one embodiment, the incident coupler, extension coupler, and output coupler on each waveguide plate are arranged in an L-shape.
[0041] Specifically, the distribution of the input couplers, output couplers, and extension couplers on each waveguide plate can be represented in the following two ways:
[0042] One type is, such as Figure 2As shown, the corresponding input couplers and extension couplers on each waveguide plate are distributed along the X-axis, and the extension couplers and output couplers are distributed along the Y-axis. Each input coupler changes periodically along the X-axis. The zeroth diffraction order of each extension coupler extends the corresponding light along the X-axis direction, and the first diffraction order transmits the corresponding light along the Y-axis direction. The light transmitted along the Y-axis direction passes through the output of the first diffraction order of the corresponding output coupler (periodically along the Y-axis direction) and enters the human eye.
[0043] Another type is, such as Figure 3 As shown, the corresponding input couplers and extension couplers on each waveguide plate are distributed along the Y-axis, and the extension couplers and output couplers are distributed along the X-axis. Each input coupler changes periodically along the Y-axis. The zeroth diffraction order of each extension coupler extends the corresponding light along the Y-axis direction, and the first diffraction order transmits the corresponding light along the X-axis direction. The light transmitted along the X-axis direction passes through the output of the first diffraction order of the corresponding output coupler (periodically along the X-axis direction) and enters the human eye.
[0044] In one embodiment, the diagonal field of view of the micro-optomechanical system 1 is 35 degrees, with the horizontal field of view being 32 degrees and the vertical field of view being 16 degrees. The wavelengths of the first wavelength light are λ1 = 450 nm, the second wavelength light is λ2 = 530 nm, and the third wavelength light is λ3 = 630 nm. Based on the grating equation and the principle of total internal reflection, the refractive index of each waveguide plate can be n = 1.8. The angle θ between the micro-optomechanical system 1 and the X-axis or Y-axis is 6 degrees. The period of the first incident coupler 2 is P1 = 290 nm, and the period of the second incident coupler 3 is P2 = 500 nm. Each period is along the Y-axis direction to avoid crosstalk between the first and third wavelength light in different waveguide plates, while ensuring that the second wavelength light outputs a complete field of view.
[0045] In another embodiment, the diagonal field of view of the micro-optomechanical system 1 is 40 degrees, with a horizontal field of view of 36 degrees and a vertical field of view of 20 degrees. The wavelengths of the first wavelength light are λ1 = 450 nm, the second wavelength light is λ2 = 530 nm, and the third wavelength light is λ3 = 630 nm. Based on the grating equation and the principle of total internal reflection, the refractive index of each waveguide plate can be n = 1.9. The angle θ between the micro-optomechanical system 1 and the X-axis or Y-axis is 5 degrees. The period of the first incident coupler 2 is P1 = 270 nm, and the period of the second incident coupler 3 is P2 = 500 nm. Each period is along the Y-axis to avoid crosstalk between the first and third wavelength light in different waveguide plates, while ensuring that the second wavelength light outputs a complete field of view.
[0046] like Figure 4As shown, a K-Layout diagram is used to represent one method of representing the wave vector direction of each ray in the first waveguide plate 4. Figure 4 The horizontal and vertical coordinates in the figure both represent wave vector coordinates:
[0047] Region A represents the field of view corresponding to the micro-optomechanism 1, which includes a first wavelength light, a second wavelength light, and a third wavelength light (with wavelengths of 450nm, 530nm, and 630nm respectively). Through the first diffraction order of the first incident coupler 2, the first wavelength light is completely coupled into the first waveguide plate 4 with a refractive index of n, represented by region B. Simultaneously, the light at field of view a is coupled into the first waveguide plate 4 with a refractive index of n, while the light at field of view b cannot be coupled into the first waveguide plate 4 with a refractive index of n for total internal reflection, represented by region C. Furthermore, it is ensured that the third wavelength light in the fourth field of view cannot be coupled into the first waveguide plate 4 with a refractive index of n for total internal reflection, represented by region D. This avoids crosstalk between the first and third wavelength light in the first waveguide plate 4.
[0048] like Figure 5 As shown, a K-Layout diagram is used to represent one method of representing the wave vector direction of each ray in the second waveguide plate 5. Figure 5 The horizontal and vertical coordinates in the figure both represent wave vector coordinates:
[0049] Region A represents the field of view corresponding to the micro-optomechanism 1, which includes a first wavelength light, a second wavelength light, and a third wavelength light (with wavelengths of 450nm, 530nm, and 630nm respectively). Through the first diffraction order of the second incident coupler 3, the third wavelength light is completely coupled into the second waveguide plate 5 with a refractive index of n, denoted by region E. Simultaneously, the light at field of view b is coupled into the second waveguide plate 5 with a refractive index of n, while the light at field of view a cannot be coupled into the second waveguide plate 5 with a refractive index of n for total internal reflection, denoted by region F. Furthermore, the first wavelength light from the first field of view cannot be coupled into the second waveguide plate 5 with a refractive index of n for total internal reflection, denoted by region G. This avoids crosstalk between the first and third wavelength light in the second waveguide plate 5.
[0050] This waveguide display uses corresponding incident couplers on each waveguide plate. The first diffraction order of the first incident coupler ensures that the light of the first wavelength and the light at field angle a are completely coupled into the first waveguide plate for total internal reflection transmission. The first diffraction order of the second incident coupler ensures that the light at field angle b and the light of the third wavelength are completely coupled into the second waveguide plate for total internal reflection transmission. Through extension couplers, crosstalk between the first and third wavelengths is prevented, thereby improving the brightness and color uniformity of the output image. Compared with the prior art, this waveguide display reduces the three waveguide plates to two, reducing the weight of the entire waveguide display. At the same time, it can prevent crosstalk between light without the use of polarization devices and light-absorbing materials.
[0051] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0052] The embodiments described above are merely specific and detailed examples of the embodiments described in this application, and should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. Therefore, the scope of protection of this patent application should be determined by the appended claims.
Claims
1. A waveguide display that avoids color crosstalk, comprising a micro-optomechanic (1), characterized in that: The waveguide display further includes a first incident coupler (2), a second incident coupler (3), a first waveguide plate (4), a second waveguide plate (5), a first extension coupler, a second extension coupler, a first output coupler (6), and a second output coupler (7), wherein: The first waveguide plate (4) and the second waveguide plate (5) are arranged side by side in sequence; The first incident coupler (2), the first extended coupler, and the first output coupler (6) are attached to the first waveguide plate (4) and are all located on the side away from the second waveguide plate (5). The second incident coupler (3), the second extended coupler, and the second output coupler (7) are attached to the second waveguide plate (5) and are all located on the side close to the second waveguide plate (5). The micro-optomechanical system (1) outputs a first wavelength light, a second wavelength light, and a third wavelength light. The field of view of each wavelength light is equal. Each incident coupler uses the first diffraction order and the zeroth diffraction order to divide the second wavelength light into a field of view light and a field of view light. The field of view of the a field of view light and the field of view of the b field of view light are both greater than half of the complete field of view of the second wavelength light. The first incident coupler (2) uses the first diffraction order to couple the first wavelength light and the a field-of-view light into the first waveguide plate (4), and after total internal reflection by the first waveguide plate (4), it is extended by the first extension coupler and then coupled out from the first output coupler (6) to the human eye (8). The first incident coupler (2) uses the zero-order diffraction order to make the b field-of-view light and the third wavelength light pass through the first waveguide plate (4) and reach the second incident coupler (3). The second incident coupler (3) uses the first diffraction order to couple the b field-of-view light and the third wavelength light into the second waveguide plate (5), and after total internal reflection by the second waveguide plate (5), it is extended by the second extension coupler and then coupled out from the second output coupler (7) to the human eye (8), thereby achieving uniformity of color and brightness of the coupled image.
2. The waveguide display for avoiding color crosstalk as described in claim 1, characterized in that: Each of the waveguide plates is made of transparent high-refractive-index glass with a refractive index of 1.7 to 2.
0.
3. The waveguide display for avoiding color crosstalk as described in claim 1, characterized in that: The wavelength of the first wavelength light is 440nm~460nm, the wavelength of the second wavelength light is 520nm~540nm, and the wavelength of the third wavelength light is 615nm~635nm.
4. The waveguide display for avoiding color crosstalk as described in claim 1, characterized in that: Each of the incident couplers is a one-dimensional periodic structure, and the period of each incident coupler is 200nm~500nm.
5. The waveguide display for avoiding color crosstalk as described in claim 1, characterized in that: The diagonal field of view of the micro-optical machine (1) is 28°~50°.
6. The waveguide display for avoiding color crosstalk as described in claim 1, characterized in that: Each of the couplers is a surface relief grating or a volume holographic grating.
7. The waveguide display for avoiding color crosstalk as described in claim 1, characterized in that: The incident coupler, extension coupler, and output coupler on each of the waveguide plates are arranged in an L-shape.