Optical waveguide and near-to-eye display module

Abstract

The embodiment of the invention discloses an optical waveguide and a near-to-eye display module, and the optical waveguide is provided with a filter layer at one side far away from the human eye, and the filter layer is used for reflecting the light transmitted in the optical waveguide, so that the information leakage caused by the light transmitted to the outside through the optical waveguide can be avoided, and meanwhile, the wearing aesthetic property is not damaged. And the wearing experience of the user is improved.

Description

Technical Field

[0001] The present application relates to the field of scanning display technology, and in particular to an optical waveguide and a near-eye display module. Background Art

[0002] In some augmented reality (AR) devices (such as AR glasses), diffractive waveguides can be used to couple in and out light. When outcoupling, the diffractive waveguide will have transmission and reflection orders. The wearer's eyes will receive part of the light, while the other part will be emitted to the outside world.

[0003] When a user wears an AR device and is in a social environment, the light emitted to the outside world through the waveguide will allow other people to see the content displayed by the AR device, resulting in information leakage; at the same time, to the outside world, the wearer's eyes will appear to be glowing. This will cause great damage to the aesthetics and privacy, and seriously affect the user's wearing experience. Summary of the invention

[0004] Based on the above content, the present application provides an optical waveguide and a near-eye display module to solve the problems of information leakage and aesthetics in existing optical waveguides.

[0005] Based on one aspect of the present application, an embodiment of the present application provides an optical waveguide, which includes a waveguide substrate, at least one coupling-in region, at least one coupling-out region, and a filter layer; wherein the filter layer is arranged on a side of the optical waveguide away from a human eye, and the filter layer is used to reflect part of the light transmitted in the optical waveguide.

[0006] Optionally, the filter layer includes a filter.

[0007] Optionally, the filter layer includes a filter film layer.

[0008] Optionally, the filter layer at least covers the outcoupling region, so that the filter layer can reflect light with different exit angles after passing through the outcoupling region.

[0009] Optionally, the reflectivity of the filter layer is 100% or close to 100%.

[0010] An embodiment of the present application provides a near-eye display module, comprising a light source and the optical waveguide described in claims 1 to 4, wherein the image light generated by the light source enters the optical waveguide through the coupling-in region of the optical waveguide, part of the light is output to the human eye through the coupling-out region of the optical waveguide, and part of the light passes through the coupling-out region and is reflected to the human eye via the filter layer of the optical waveguide.

[0011] Optionally, the central wavelength reflected by the filter layer corresponds to the central wavelength of the light source.

[0012] Optionally, the reflection spectral width of the filter layer corresponds to the spectral width of the light source.

[0013] Optionally, the light source is a narrow-band light source or a wide-spectrum light source.

[0014] Optionally, the filter layer has a set reflection spectrum width.

[0015] In the scheme of the embodiment of the present application, a filter layer is arranged on the side of the optical waveguide away from the human eye. The filter layer is used to reflect the light transmitted in the optical waveguide, which can prevent the light emitted to the outside through the optical waveguide from entering the eyes of the person talking and causing information leakage. At the same time, it will not destroy the wearing aesthetics and improve the user's wearing experience.

[0016] Other features and advantages of the present application will be described in the subsequent description, and partly become apparent from the description, or understood by implementing the technical solution of the present application. The purpose and other advantages of the present application can be realized and obtained through the structures and / or processes specifically pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0018] Figure 1 is a schematic diagram of a waveguide structure provided in an embodiment of the present application;

[0019] Figure 2 This is a schematic diagram of an optical path for diffraction and extended transmission of light in a waveguide provided in an embodiment of the present application;

[0020] Figure 3 This is a schematic diagram of a waveguide structure with a filter layer provided in an embodiment of the present application;

[0021] Figure 4 It is a spectrum schematic diagram of a filter layer provided in an embodiment of the present application. DETAILED DESCRIPTION

[0022] The present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It should also be noted that, for ease of description, only the parts related to the relevant invention are shown in the accompanying drawings.

[0023] refer to Figure 1, an optical waveguide 100 provided in an embodiment of the present application, includes: a waveguide substrate 101, a coupling-in region 102 and a coupling-out region 103, a grating structure is arranged in the coupling-in region 102 and the coupling-out region 103, and the grating structure can be realized by using processes such as imprinting, coating, etching, etc., which is not limited here.

[0024] certainly, Figure 1 The contours and relative positions of the coupling-in region 102 and the coupling-out region 103 shown in the figure are exemplary. In practical applications, the coupling-in region 102 may not be Figure 1 The circular outline shown in the figure may be a rounded rectangle, a trapezoid, etc. Similarly, the outline of the outcoupling region 103 may also be a trapezoid, a rounded rectangle. The relative positions of the incoupling region 102 and the outcoupling region 103 may be arranged above and below each other, instead of the current Figure 1 Left and right distribution under viewing angle. Figure 1 The illustrated coupling-in region 102 and the coupling-out region 103 should not be understood as limiting the present application.

[0025] In actual applications, the waveguide 100 is usually used to output image light to the observer's eyes (left eye or right eye). If it is to be used as binocular AR glasses, at least two waveguide 100 structures are required to correspond to the observer's eyes respectively. In other cases, the lateral (x-axis direction) size of the outcoupling region 103 is sufficient to cover the observer's eyes. When used as binocular AR glasses, only one waveguide 100 structure is required.

[0026] Figure 1 The figure shows the angle of view when the waveguide 100 is facing the observer's eyes with the side of the outcoupled light, which is also the angle of view when the user wears the AR glasses normally. The figure shows the xy coordinate system. In the embodiment of the present application, the direction perpendicular to the xy plane can be considered as the positive direction of the z axis (the z axis is not in the Figure 1 Those skilled in the art should understand that in actual use, there will be certain deviations in the viewing angle relationship between the human eye and the waveguide, such as angle deviation caused by wearing, etc. Therefore, the coordinate system and corresponding viewing angle described in the present application are ideal, and a small amount of deviation is allowed in actual application.

[0027] The applicant has found that, in general, the optical path of the light entering the waveguide coupling-in region 102 propagating between the coupling-in region 102 and the coupling-out region 103 is as follows: Figure 2 As shown, the light is transmitted from the coupling-in region 102 to the coupling-out region 103, and diffracted by the coupling-out grating in the coupling-out region 103, thereby extending the transmission and generating light rays transmitted in different directions, including: light rays that continue to be transmitted in the direction of the light rays, light rays coupled out in the direction of the human eye, and a series of light rays that are transmitted obliquely downward (such as Figure 2The light shown by the dotted line in the middle is the light emitted to the outside world through the waveguide. When a user wears an AR device for face-to-face communication, the light emitted to the outside world will enter the eyes of the person talking, causing information leakage. At the same time, to the outside world, the wearer's eyes will appear to be glowing, which will cause great damage to the aesthetics and information confidentiality, and seriously affect the user's wearing experience.

[0028] To solve the above problem, the solution in the embodiment of the present application adds a filter layer at a position where the waveguide is far away from the human eye (that is, close to the outside world). Figure 3 The optical waveguide 100 includes a waveguide substrate 101, an incoupling region 102, an outcoupling region 103 and a filter layer 104; wherein the filter layer 104 is arranged on a side of the optical waveguide 100 away from the human eye, and the filter layer 104 is used to reflect the light of the wavelength band transmitted in the optical waveguide, so that the light emitted by the optical waveguide to the outside is reflected back to the human eye by the filter layer 104, which can solve the problems of information leakage, unsightly and poor confidentiality, and increase the brightness of the light transmitted by the waveguide entering the human eye.

[0029] In the present application embodiment, Figure 3 As shown, the filter layer 104 can be a filter, and the filter can be implemented by bonding. In this way, the filter layer 104 and the waveguide substrate 101 are closely attached. The filter can also be implemented by installing and fixing, specifically, in the frame (for example, in Figure 3 A corresponding fixing structure is provided on the waveguide substrate 101 for installing and fixing the filter. In this way, there is a gap between the filter and the waveguide substrate 101. Of course, the fixing of the filter can be detachable.

[0030] In other embodiments, the filter layer 104 may also be a filter film layer, including a multi-layer film structure formed by plating or coating, and a micro-nano structure having the same function.

[0031] In the embodiment of the present application, it is assumed that the transmitted light in the waveguide includes three bands, the central wavelengths of the three bands are λ1, λ2 and λ3, and the spectral widths are Δλ1, Δλ2, and Δλ3, respectively. The reflectivity of the filter layer 104 is shown in Figure 4. The reflection wavelength of the filter layer 104 corresponds to the central wavelength of the transmitted light in the waveguide, and the spectral width of the filter layer 104 corresponds to the spectral width of the transmitted light in the waveguide. Within the set spectrum range, the reflectivity of the filter layer 104 can be 100% or close to 100%, thereby effectively avoiding information leakage.

[0032] In other embodiments, the wavelength band of the light transmitted in the waveguide may be one or more, and the reflection wavelength of the filter may correspond one-to-one with the wavelength band of the light transmitted in the waveguide.

[0033] It can be seen from the above scheme that if the spectral width of the filter layer 104 is too large, most of the external light will be reflected back. Therefore, the scheme in the embodiment of the present application is particularly suitable for the laser band. Because the spectral width of the laser is narrow, the spectral width of the filter layer 104 is also narrow. In this way, when the filter layer 104 is used, the filter layer 104 will have less reflection loss of natural light entering the human eye from the outside. That is to say, the light source in the embodiment of the present application can adopt a narrow-band light source, such as a narrow-band laser light source. Of course, the light source can also be other wide-spectrum light sources, such as LED light sources, OLED light sources, etc., and the present application does not impose any restrictions on this.

[0034] In the embodiment of the present application, the light source is taken as an example of a three-color laser light source of R, G, and B. For example, assuming that the central wavelength λ1 of the blue light source is 450nm, the central wavelength λ2 of the green light source is 520nm, and the central wavelength λ3 of the red light source is 638nm, and the spectral widths Δλ1, Δλ2, and Δλ3 are all 2nm, then the reflection wavelength of the filter layer 104 corresponds to the central wavelength of the light source, which are 450nm, 520nm, and 638nm, respectively, and the spectral widths are all 2nm, thereby ensuring that the filter layer 104 can reflect the light emitted to the outside world back to the human eye. It should be noted that the above data are only examples. In actual applications, the wavelength and spectral width reflected by the filter layer 104 can be set according to actual conditions.

[0035] In the embodiment of the present application, in order to ensure the reflection effect of the filter layer 104, the area where the filter layer 104 is located at least covers the outcoupling area 103 of the optical waveguide 100. Figure 3 As shown, the light passing through the outcoupling region 103 may have different emission angles, and the filter layer 104 can reflect the light with different emission angles passing through the outcoupling region 103, thereby ensuring the reflection effect, avoiding information leakage and destroying the aesthetics.

[0036] Based on the optical waveguide described in the above content, a near-eye display module is also provided in an embodiment of the present application, which can be applied to AR glasses. The near-eye display module includes: a light source and the optical waveguide described in the above embodiment, the image light generated by the light source enters the optical waveguide through the coupling-in region of the optical waveguide, part of the light is output to the human eye through the coupling-out region of the optical waveguide, and part of the light passes through the coupling-out region and is reflected to the human eye via the filter layer of the optical waveguide.

[0037] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above invention concept. For example, the above features are replaced with the technical features with similar functions disclosed in this application (but not limited to) by each other to form a technical solution.

Claims

1. An optical waveguide, characterized in that: The optical waveguide comprises a waveguide base, at least one coupling-in region, at least one coupling-out region and a filter layer; wherein the filter layer is arranged on a side of the optical waveguide away from human eyes, and the filter layer is used to reflect part of the light transmitted in the optical waveguide.

2. The optical waveguide according to claim 1, wherein The filter layer includes a filter.

3. The optical waveguide according to claim 1, wherein The filter layer includes a filter film layer.

4. The optical waveguide according to claim 1, wherein The filter layer at least covers the outcoupling region, so that the filter layer can reflect light with different exit angles after passing through the outcoupling region.

5. The optical waveguide according to claim 1, wherein The reflectivity of the filter layer is 100% or close to 100%.

6. A near-eye display module, characterized in that: The invention comprises a light source and the optical waveguide as claimed in claims 1 to 4, wherein the image light generated by the light source enters the optical waveguide through the coupling-in region of the optical waveguide, part of the light is output to the human eye through the coupling-out region of the optical waveguide, and part of the light passes through the coupling-out region and is reflected to the human eye through the filter layer of the optical waveguide.

7. The near-eye display module according to claim 6, wherein: The central wavelength reflected by the filter layer corresponds to the central wavelength of the light source.

8. The near-eye display module according to claim 6, wherein: The reflection spectrum width of the filter layer corresponds to the spectrum width of the light source.

9. The near-eye display module according to claim 6, wherein: The light source is a narrow-band light source or a wide-spectrum light source.

10. The near-eye display module according to claim 8, wherein: The filter layer has a set reflection spectrum width.

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