Optical module, display device and augmented reality device with anti-theft function

Abstract

The present invention discloses an optical module, a display device and an augmented reality device with an anti-theft function. The optical module comprises: a stacked grating waveguide and a selective light absorption component; the grating waveguide is arranged on the side close to the human eye, and is used to transmit the incident image light and the external environment light to the human eye; the selective light absorption component is arranged on the side away from the human eye, and is used to absorb the redundant light generated by the image light after passing through the grating waveguide and transmit the external environment light. The present invention uses a photonic crystal waveguide with a defective channel as a selective light absorption component to absorb the redundant light generated by a traditional waveguide grating, so as to achieve the effect of eliminating the redundant light, so that the redundant light will not leak into the real environment, and prevent the user's privacy from being peeped.

Description

Technical Field

[0001] The present invention relates to the field of augmented reality technology, and in particular to an optical module, a display device and an augmented reality device with an anti-theft function. Background Art

[0002] Augmented Reality (AR) technology is a new technology that "seamlessly" integrates real-world information and virtual-world information. It uses computers and other scientific technologies to simulate and superimpose physical information (visual information, sound, taste, touch, etc.) that is difficult to experience within a certain time and space in the real world, and then applies virtual information to the real world and is perceived by human senses, thereby achieving a sensory experience beyond reality. That is, the real environment and virtual objects are superimposed on the same screen or space in real time.

[0003] In the current augmented reality field, grating waveguide is a common technical solution, such as Figure 1 As shown, the image light emitted by the image source 300 is coupled into the optical waveguide structure 400 by the coupling grating 100, and after being totally reflected by the optical waveguide structure 400, it is coupled out by the coupling grating 200 and enters the human eye 500 to form an image. At the same time, the light of the real scene outside enters the optical waveguide structure 400 and enters the human eye after being transmitted, so that the light emitted by the image source 300 and the real light outside are superimposed at the human eye, thereby forming an augmented reality effect. In practical applications, the coupling grating 200 often has multiple diffraction orders, resulting in information redundancy, such as Figure 2 As shown in the figure, assuming that the human eye observes from above the optical waveguide structure, light rays T1 and T2 are the image information we need, while light rays R1 and R2 are redundant. Because light rays R1 and R2 will leak into the real external environment, it is likely to cause user privacy leakage. Therefore, we only need light rays T1 and T2 that can enter the human eye, and eliminate other light rays R1 and R2 to prevent user information leakage.

[0004] Therefore, the prior art has defects and needs to be improved. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and provide an optical module with an anti-theft function to eliminate redundant light generated after the image light passes through the grating waveguide.

[0006] Another object of the present invention is to provide a display device to solve the problem of information leakage caused by the existence of multiple diffraction orders in the grating waveguide in the existing display equipment.

[0007] Another object of the present invention is to provide an augmented reality device to solve the problem of information leakage caused by the existence of multiple diffraction orders in the grating waveguide in the existing augmented reality device.

[0008] To achieve the above objectives, the present invention is implemented through the following technical solutions: The present invention provides an optical module with anti-theft function, including: a stacked grating waveguide and a selective light absorption component; the grating waveguide is arranged on the side close to the human eye, and is used to transmit the incident image light and the external ambient light to the human eye; the selective light absorption component is arranged on the side away from the human eye, and is used to absorb the redundant light generated after the image light passes through the grating waveguide and transmit the external ambient light.

[0009] Furthermore, the frequency of the light absorbed by the selective light absorption component corresponds to the frequency of the image light.

[0010] Further, the selective light absorption component comprises: a photonic crystal waveguide and a light absorption portion provided on the photonic crystal waveguide;

[0011] The photonic crystal waveguide includes a photonic bandgap, on which a connected defect channel is arranged; the photonic bandgap is used to prevent the image light from leaking out; one port of the defect channel is arranged corresponding to the coupling element of the grating waveguide, and the other port of the defect channel is arranged corresponding to the light absorption part, so as to transmit the redundant light to the light absorption part, and then the light absorption part absorbs the redundant light.

[0012] Furthermore, the light absorbing portion is provided at one end of the photonic crystal waveguide and is located at the same end as the coupling element of the grating waveguide.

[0013] Furthermore, the light absorbing portion is provided on a cross section of one end of the photonic crystal waveguide.

[0014] Furthermore, the defect channel includes a transverse channel and at least one longitudinal channel connected to the transverse channel, one port of the transverse channel is connected to the light absorption part, and the other port is connected to a port of the longitudinal channel, and the other port of the longitudinal channel is arranged toward the coupling element of the grating waveguide.

[0015] Furthermore, the photonic crystal waveguide includes a plurality of photonic crystal units that are periodically arranged in two or three dimensions.

[0016] Furthermore, the size of each of the photonic crystal units is on the order of wavelength, and the gap between two adjacent photonic crystal units is on the order of wavelength.

[0017] The present invention also provides a display device with an anti-theft function, comprising an image source emitting image light and the above-mentioned optical module.

[0018] The present invention also provides an augmented reality device, comprising the above-mentioned display device.

[0019] By adopting the above scheme, the present invention provides an optical module, a display device and an augmented reality device with anti-theft function, which utilizes a photonic crystal waveguide with a defective channel as a selective light absorption component to absorb the redundant light generated by a traditional grating waveguide to achieve the effect of eliminating the redundant light, so that the redundant light will not leak into the real environment, thereby preventing the user's privacy from being peeped; it can also prevent light leakage and avoid the light emitted by the image source from being scattered into the real environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the structure of a grating waveguide in the prior art.

[0021] Figure 2 It is a schematic diagram of the existence of multiple diffraction orders of a grating in the prior art.

[0022] Figure 3 It is a schematic structural diagram of an optical module with anti-theft function according to the present invention.

[0023] Figure 4 It is a schematic diagram of the structure of a one-dimensional photonic crystal in the present invention.

[0024] Figure 5 It is a schematic diagram of the structure of the two-dimensional photonic crystal in the present invention.

[0025] Figure 6 It is a schematic diagram of the structure of the three-dimensional photonic crystal in the present invention.

[0026] Figure 7 It is a schematic structural diagram of an embodiment of a photonic crystal waveguide in the present invention.

[0027] Figure 8 FIG. 4 is a schematic structural diagram of another embodiment of the photonic crystal waveguide in the present invention. DETAILED DESCRIPTION

[0028] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0029] The present invention provides a display device with anti-theft function, such as Figure 3 As shown, it includes an image source 1 and an optical module. The optical module uses a defective photonic crystal waveguide to absorb the redundant light generated by a traditional grating waveguide to achieve the effect of eliminating the redundant light. This technical solution can be applied to augmented reality devices such as AR glasses and can also be applied to devices such as head-up display devices (HUD). Please refer to Figure 3 The optical module includes: a stacked grating waveguide and a selective light absorption component 6.

[0030] The grating waveguide is arranged on the side close to the human eye, and is used to transmit the incident image light and the external environment light to the human eye, and specifically includes: a waveguide substrate 3, a coupling element 2, and a coupling element 4. The coupling element 2 is arranged at one end of the waveguide substrate 3, and the coupling element 4 is arranged at the other end of the waveguide substrate 3. Preferably, the coupling element 2 and the coupling element 6 are arranged on the surface of the same side of the waveguide substrate 3, and are arranged close to the side of the human eye 5, so as to facilitate user use. The selective light absorption component 6 is arranged on the side away from the human eye 5, and is used to absorb a specific frequency of light. Because the grating waveguide has multiple diffraction orders and generates redundant light, the embodiment of the present invention adds a selective light absorption component 6, and its purpose is to absorb the redundant light generated after the image light passes through the grating waveguide. In addition, the selective light absorption component 6 also has the function of transmitting the external environment light. After the external environment light passes through the selective light absorption component 6, it enters the waveguide substrate 3, and is incident on the human eye after being transmitted through the waveguide substrate 3. The frequency of the light absorbed by the selective light absorption component 6 corresponds to the frequency of the image light emitted by the image source 1, that is, the frequency is the same.

[0031] The image source 1 in the present invention is a display device that can provide image information, and can be a display module such as LCD, OLED, micro-LED, LCoS, etc. The coupling element 2 and the coupling element 4 are used for coupling in and out of the image light, and can use a linear grating or a two-dimensional grating, which can both transmit ambient light and have a certain pupil expansion function. The waveguide substrate 3 is usually made of a material with a high refractive index and low loss (glass, resin, etc.).

[0032] The working principle of the optical module with anti-theft function is as follows: the image light emitted by the image source 1 is coupled into the waveguide substrate 3 through the coupling element 2, the image light is totally reflected in the waveguide substrate 3, and is coupled out through the coupling element 4 to be incident on the human eye 5. At the same time, in this process, the redundant light generated by the existence of multiple diffraction orders in the grating waveguide enters the selective light absorption component 6, and propagates to the other end of the selective absorption component 6, and is finally absorbed by the selective light absorption component 6, thereby preventing these redundant light from being diverged into the real environment, thereby achieving an anti-peeping effect and protecting the user's privacy. Since the selective light absorption component 6 is only set for light of a specific frequency, and it is preferably transparent. Therefore, since the external ambient light from the real scene has a very wide frequency range, the display device still has a high comprehensive transmittance in the human eye observation area. After the external ambient light passes through the selective light absorption component 6, it is emitted to the human eye 5 through the waveguide substrate 3, thereby realizing the superposition of the real scene and the virtual scene, realizing the augmented reality effect, and thus being able to ensure the quality of AR display.

[0033] On the other hand, when determining the selective light absorption component, photonic crystals are proposed to be used. Photonic crystals are artificial electromagnetic media formed by arranging media with different refractive indices in a specific periodic pattern, such as Figure 4 , Figure 5 and Figure 6 As shown, according to the periodic changes in space, they can be divided into three categories: one-dimensional photonic crystals, two-dimensional photonic crystals and three-dimensional photonic crystals, where A and B are materials with different refractive indexes, and a is the lattice constant. When the dielectric constants of material A and material B change sufficiently, and the lattice constant a is comparable to the wavelength of the light wave, the photonic crystal will form a "photonic bandgap", so that light waves with frequencies in the bandgap range cannot pass through. Therefore, photonic crystals can be used to block light waves of specific frequencies. When there are defects in the photonic crystal, the blocked light waves can propagate in the defects. As long as the defect arrangement inside the photonic crystal is controlled, the propagation trajectory of the light wave can be controlled.

[0034] Based on the above characteristics of photonic crystals, the selective light absorption component 6 can be realized by photonic crystals. Figure 3 and Figure 7 As shown, the selective light absorption component 6 includes a photonic crystal waveguide 61 and a light absorption portion 62 disposed on the photonic crystal waveguide 61. The light absorption portion 62 is disposed at one end of the photonic crystal waveguide 61 and is located at the same end as the coupling element 2 of the grating waveguide. The light absorption portion 62 is specifically disposed on a cross section of one end of the photonic crystal waveguide 61, as shown in FIG. Figure 3 shown.

[0035] The photonic crystal waveguide 61 is made of materials such as diamond and semiconductor materials (such as SIO2), and includes a photonic bandgap (not shown). The photonic bandgap is used to prevent the image light from leaking out. A connected defect channel 67 is provided on the photonic bandgap to transmit the redundant light to the light absorbing part 62. Figure 7 One port of the defect channel 67 is arranged corresponding to the coupling element 4 of the grating waveguide, and the other port of the defect channel 67 is arranged corresponding to the light absorbing portion 62, so as to transmit the redundant light to the light absorbing portion 62. Due to the existence of the photon bandgap, the redundant light (invalid image light) can only be transmitted along the defect channel 67 to the light absorbing portion 62, and finally absorbed by the light absorbing portion 62. The light absorbing portion 62 can be made of common light absorbing materials, such as black foam, etc.

[0036] In specific implementation, the structure of the photonic crystal waveguide 61 may include: a plurality of photonic crystal units arranged in a two-dimensional or three-dimensional periodic manner, the size and period of the photonic crystal units are optimized according to the wavelength of the image source, so that the light emitted by the image source is in the photonic bandgap and can only propagate in the defect channel 67. The size of each photonic crystal unit is of the order of wavelength, and the gap between two adjacent photonic crystal units is of the order of wavelength.

[0037] Please continue reading Figure 3 , Figure 7 , the defect channel 67 includes a transverse channel 64 and at least one longitudinal channel 63 connected to the transverse channel 64, one port of the transverse channel 64 is connected to the light absorption part 62, and the other port is connected to a port of the longitudinal channel 63, and the other port of the longitudinal channel 63 is arranged toward the coupling-out element 4 of the grating waveguide. The defect channel 67 in the photonic crystal waveguide 61 can have different arrangements. Generally, the image presented in the visual area (near the coupling-out element 4) has a certain size, so the number of openings of the defect channel 67 (the number of longitudinal channels 63) can be appropriately increased, that is, there are multiple defect channel openings in the image coupling direction, which can further prevent invalid redundant light from being reflected back into the optical waveguide structure 3 and then entering the human eye 5, affecting the display effect. Of course, the opening size and number of the defect channel 67 are adjusted according to the wavelength of the image light source and the reflection conditions to ensure a better image viewing effect. Figure 7 As shown, the defective channel 67 is "L"-shaped, including a transverse channel 64 and a longitudinal channel 63 connected to the transverse channel, and the transverse channel 64 and the longitudinal channel 63 may be perpendicular to each other; Figure 8 As shown, the defective channel 68 is in a comb shape, including a transverse channel 66 and three longitudinal channels 65 connected to the transverse channel.

[0038] The present invention also provides an augmented reality device, comprising the above-mentioned display device.

[0039] In summary, the present invention provides an optical module, a display device and an augmented reality device with anti-theft function, which utilize a photonic crystal waveguide with a defective channel as a selective light absorption component to absorb the redundant light generated by a traditional grating waveguide, so as to achieve the effect of eliminating the redundant light, so that the redundant light will not leak into the environment, thereby preventing the user's privacy from being peeped; it can also prevent light leakage, avoid the light emitted by the image source from scattering into the real environment, and enhance the product experience effect.

[0040] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An optical module with anti-theft function, characterized in that: include: A stacked grating waveguide and a selective light absorption component; the grating waveguide is arranged on a side close to the human eye, and is used to transmit the incident image light and the external environment light to the human eye; the selective light absorption component is arranged on a side away from the human eye, and is used to absorb the redundant light generated after the image light passes through the grating waveguide and transmit the external environment light; The selective light absorption component comprises: a photonic crystal waveguide and a light absorption portion disposed on the photonic crystal waveguide; The photonic crystal waveguide includes a photonic bandgap, on which a connected defect channel is arranged; the photonic bandgap is used to prevent the image light from leaking out; one port of the defect channel is arranged corresponding to the coupling element of the grating waveguide, and the other port of the defect channel is arranged corresponding to the light absorption part, so as to transmit the redundant light to the light absorption part, and then the light absorption part absorbs the redundant light.

2. The optical module with anti-theft function according to claim 1, characterized in that: The frequency of the light absorbed by the selective light absorption component corresponds to the frequency of the image light.

3. The optical module with anti-theft function according to claim 1, characterized in that: The light absorbing portion is arranged at one end of the photonic crystal waveguide and is located at the same end as the coupling element of the grating waveguide.

4. The optical module with anti-theft function according to claim 3, characterized in that: The light absorbing portion is arranged on a cross section of one end of the photonic crystal waveguide.

5. The optical module with anti-theft function according to claim 1, characterized in that: The defect channel includes a transverse channel and at least one longitudinal channel connected to the transverse channel, one port of the transverse channel is connected to the light absorption part, and the other port is connected to a port of the longitudinal channel, and the other port of the longitudinal channel is arranged toward the coupling element of the grating waveguide.

6. The optical module with anti-theft function according to claim 1, characterized in that: The photonic crystal waveguide includes a plurality of photonic crystal units which are arranged periodically in two or three dimensions.

7. The optical module with anti-theft function according to claim 6, characterized in that: The size of each photonic crystal unit is on the order of wavelength, and the gap between two adjacent photonic crystal units is on the order of wavelength.

8. A display device, characterized in that: The optical module comprises an image source emitting image light and the optical module as claimed in any one of claims 1 to 7.

9. An augmented reality device, characterized in that: A display device comprising the display device according to claim 8.

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