Retinal projection apparatus and near-eye display device

Abstract

This application provides a retinal projection device and a near-eye display device, which can effectively solve the problems of small exit pupil and limited eyebox in near-eye display systems by adopting a form that separates the image display area and the projection area. The retinal projection device includes: an LBS optical engine for projecting image light; and a holographic optical element disposed on the projection side of the LBS optical engine for focusing the image light projected by the LBS optical engine in front of the pupil; wherein the LBS optical engine forms a fixed projection area and a variable image display area located within the projection area on the holographic optical element.

Description

Technical Field

[0001] This application relates to the field of near-eye display technology, and in particular to a retinal projection device and a near-eye display apparatus. Background Technology

[0002] Conventional LBS (Laser Beam Scanning) + HOE (holographic optical elements) near-eye display solutions are based on the principle of retinal projection display. They utilize lenses and other optical elements to converge the light carrying the virtual image (hereinafter referred to as the image beam) emitted from the image source, causing the image beam to be focused into a point at the pupil of the human eye and then directly projected onto the retina. Retinal projection display has unique advantages in the field of near-eye display: First, it can greatly reduce the role of the lens in the human eye's observation process; second, under ideal conditions, the human eye observes a full-focus image, and regardless of how the lens focuses, the human eye can see a clear virtual image. This effectively solves the problem of focal convergence conflict in near-eye displays, greatly reducing the risk of visual fatigue and dizziness caused by prolonged wear of near-eye displays.

[0003] However, conventional LBS+HOE near-eye display solutions suffer from a small exit pupil because the image beam is focused at the pupil during imaging. This makes it easy for the image beam to be blocked during eye movement, resulting in image loss. Furthermore, it is difficult to adapt to different interpupillary distances. Additionally, because the image beam projected by the LBS optical engine is a thin beam, typically less than or equal to 0.7 mm in diameter and with a divergence angle less than 1 mrad, conventional LBS+HOE near-eye display solutions struggle to design large-aperture exit pupils, resulting in exit pupil diameters typically less than 1 mm. Utility Model Content

[0004] One advantage of this application is that it provides a retinal projection device and a near-eye display device, which can adopt a form that separates the image display area from the projection area, effectively solving the problems of small exit pupil and limited eye movement range (Eyebox) in near-eye display systems.

[0005] Another advantage of this application is that it provides a retinal projection device and a near-eye display device, wherein, in one embodiment of this application, the retinal projection device can achieve the expansion of the two-dimensional eye movement range without the need for a periodic array design of holographic optical elements.

[0006] Another advantage of this application is that it provides a retinal projection device and a near-eye display device. In one embodiment of this application, the overall optical scheme of the retinal projection device is simple and lightweight, which is suitable for the overall thin and light design of the near-eye display device.

[0007] Another advantage of this application is that it provides a retinal projection device and a near-eye display device, wherein a complex structure is not required to achieve the above-mentioned objectives. Therefore, this application successfully and effectively provides a solution that not only provides a simple retinal projection device and a near-eye display device, but also increases the practicality and reliability of the retinal projection device and the near-eye display device.

[0008] To achieve at least one of the above advantages or other benefits and objectives of this application, this application provides a retinal projection device, comprising: an LBS optical engine for projecting image light; and a holographic optical element disposed on the projection side of the LBS optical engine for converging the image light projected by the LBS optical engine in front of the pupil; wherein the LBS optical engine forms a fixed projection area and a variable image display area within the projection area on the holographic optical element.

[0009] In one embodiment of this application, the distance between the convergence point formed by the holographic optical element and the pupil is between 5 mm and 15 mm.

[0010] In one embodiment of this application, the eye movement range of the retinal projection device is between 5 mm and 10 mm.

[0011] In one embodiment of this application, the eye-friendly distance of the retinal projection device is between 15 mm and 25 mm.

[0012] In one embodiment of this application, the holographic optical element is a reflective holographic element.

[0013] In one embodiment of this application, the LBS optical engine includes a laser emitter and a microelectromechanical mirror (MEMS); the MEMS is disposed on the emitting side of the laser emitter.

[0014] In one embodiment of this application, the LBS optical engine further includes an achromatic lens disposed in the optical path between the microelectromechanical mirror and the holographic optical element.

[0015] In one embodiment of this application, the achromatic lens includes a first lens having positive optical power and a second lens having negative optical power, the first lens and the second lens being cemented together to form a cemented lens.

[0016] According to another aspect of this application, one embodiment of this application provides a near-eye display device, including: a device body; and a retinal projection device as described in any of the preceding claims, disposed on the device body.

[0017] In one embodiment of this application, the near-eye display device further includes an interactive interface disposed on the device body and communicatively connected to the retinal projection device; the interactive interface is a knob, button, or touch screen.

[0018] In one embodiment of this application, the near-eye display device further includes an eye-tracking device disposed on the device body and communicatively connected to the retinal projection device; the eye-tracking device includes an ET light source and an ET camera; wherein the ET camera is communicatively connected to the LBS optical engine of the retinal projection device, and both the ET light source and the ET camera are arranged around the holographic optical elements of the retinal projection device. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of a near-eye display device according to an embodiment of this application;

[0020] Figure 2 A schematic diagram of the optical path of the retinal projection device in the near-eye display device according to the above embodiments of this application before the image display position is adjusted is shown;

[0021] Figure 3 A schematic diagram of the optical path of the retinal projection device in the near-eye display device according to the above embodiments of this application after the image display position is adjusted is shown;

[0022] Figure 4 A schematic diagram of the optical path of the eye-tracking device in the near-eye display device according to the above embodiments of this application is shown;

[0023] Figure 5 A modified embodiment of the near-eye display device according to the above embodiments of this application is shown.

[0024] Explanation of key component symbols:

[0025] 1. Near-eye display device; 10. Retinal projection device; 101. Projection area; 102. Image display area; 11. LBS optical engine; 111. Laser emitter; 112. Microelectromechanical galvanometer; 113. Achromatic lens; 1131. First lens; 1132. Second lens; 12. Holographic optical element; 20. Eye tracking device; 21. ET light source; 210. Infrared LED; 22. ET camera; 220. Infrared camera; 30. Main body of the device; 40. Interactive interface.

[0026] The above description of the main component symbols, together with the accompanying drawings and specific embodiments, provides a further detailed explanation of this application. Detailed Implementation

[0027] The following description is intended to disclose this application and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art. The basic principles of this application defined in the following description can be applied to other embodiments, modifications, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of this application.

[0028] In the description of this application, it should be understood that terms such as "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. In the description of this application, it should be noted that, unless otherwise expressly specified and limited, terms such as "connected" or "linked" should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral connection; it can refer to a mechanical connection or an electrical connection; it can refer to a direct connection or an indirect connection through a medium. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0029] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0030] Considering that conventional LBS+HOE near-eye display solutions suffer from a small exit pupil due to the image beam being converged at the pupil during imaging, image loss can easily occur when the eye moves, as the beam cannot reach the eye. Furthermore, these solutions are difficult to adapt to different interpupillary distances. Therefore, this application creatively proposes a retinal projection device and a near-eye display device that effectively solves the problems of small exit pupil and limited eyebox in near-eye display systems by separating the image display area from the projection area.

[0031] Specifically, refer to the accompanying drawings in the specification of this application. Figures 1 to 4According to one embodiment of this application, a near-eye display device 1 is provided, which may include a device body 30 and a retinal projection device 10. The retinal projection device 10 is disposed on the device body 30 and can adjust the image display position to ensure that image light can pass through the pupil to form an image on the retina, thereby obtaining a near-eye display experience. It is understood that the device body 30 mentioned in this application may be implemented as an eyeglass frame or a helmet, and this application will not elaborate further on this.

[0032] More specifically, such as Figure 2 As shown, the retinal projection device 10 may include an LBS optical engine 11 and a holographic optical element 12. The LBS optical engine 11 is used to project image light. The holographic optical element 12 is disposed on the projection side of the LBS optical engine 11 and is used to converge the image light projected by the LBS optical engine 11 onto the front of the pupil. The LBS optical engine 11 forms a fixed projection area 101 and a variable image display area 102 located within the projection area 101 on the holographic optical element 12.

[0033] In this way, when the pupil posture (such as pupil position) changes, the retinal projection device 10 can adjust the position of the image display area 102 formed by the LBS optical engine 11 on the holographic optical element 12 to correspond to the pupil position based on the pupil posture, and then the image light from the image display area 102 is transmitted through the pupil to the retina via the holographic optical element 12 to form an image on the retina.

[0034] For example, such as Figure 3 As shown, when the pupillary distance of the human eye is small and the pupil is closer to the right side of the eye movement range, the image display area 102 formed by the LBS optical engine 11 on the holographic optical element 12 moves to the left to move closer to the left side of the projection area 101, ensuring that the holographic optical element 12 can pass the image light from the image display area 102 through the pupil to form an image on the retina. Conversely, when the pupil of the human eye is closer to the left side of the eye movement range, the image display area 102 formed by the LBS optical engine 11 on the holographic optical element 12 moves to the right to move closer to the right side of the projection area 101, ensuring that the holographic optical element 12 can still pass the image light from the image display area 102 through the pupil to form an image on the retina.

[0035] It is worth noting that in conventional LBS+HOE near-eye display solutions, the projection area of ​​the LBS onto the HOE overlaps with the image display area. This means that during imaging, the image must converge at the pupil to pass through the pupil and be projected onto the retina. Therefore, if the eye moves, the image beam may not pass completely through the pupil, resulting in image loss. Furthermore, different populations (such as adults and children) have different interpupillary distances, and conventional LBS+HOE near-eye display solutions, due to their small exit pupil, are difficult to adapt to different interpupillary distances.

[0036] However, the retinal projection device 10 of this application separates the projection area 101 and the image display area 102 formed by the LBS optical engine 11 on the holographic optical element 12, making it possible for the holographic optical element 12 to converge the image light projected by the LBS optical engine 11 in front of the pupil. This not only effectively increases the exit pupil to adapt to the interpupillary distance of different people, but also expands the eye movement range without performing HOE periodic array design, ensuring that the user can always see a clear and complete image.

[0037] It is understood that the size of the projection area 101 mentioned in this application is determined by the field of view of the LBS optical engine 11; while the size of the image display area 102 mentioned in this application is determined by the pupil angle. Since the image display area 102 is located within the projection area 101 and its position is variable, the size of the image display area 102 is smaller than the size of the projection area 101. Therefore, the image display area 102 can move within the projection area 101 following changes in pupil posture, so that the image light corresponding to the moved image display area 102 can pass smoothly through the pupil to form an image on the retina, ensuring that the human eye can always observe a clear and complete image.

[0038] For example, such as Figure 2 As shown, the distance d between the convergence point formed by the holographic optical element 12 and the pupil is between 5mm and 15mm, so as to increase the exit pupil and eye movement range while ensuring that the human eye can observe a sufficiently large, clear, and complete image. Preferably, the distance between the convergence point of the holographic optical element 12 and the pupil is equal to 9mm. It can be understood that when the distance between the convergence point of the holographic optical element 12 and the pupil is less than 5mm, the exit pupil and eye movement range of the retinal projection device 10 are small, and part of the image is easily lost during the movement of the human eye, making it difficult to always observe a complete image; while when the distance between the convergence point of the holographic optical element 12 and the pupil is greater than 15mm, the size of the image display area 102 is small, and it cannot guarantee that the human eye can see a sufficiently large, clear image.

[0039] Optionally, such as Figure 2 As shown, the eye movement range EB of the retinal projection device 10 is between 5mm and 10mm, so as to reserve a large enough space for eye movement and also to be compatible with the interpupillary distance of different people.

[0040] Optionally, such as Figure 2As shown, the eye-adaptive distance range ER of the retinal projection device 10 is between 15mm and 25mm to meet the wearing requirements of the near-eye display device 1. It is understood that the eye-adaptive distance range ER mentioned in this application refers to the distance between the inner surface of the holographic optical element 12 and the pupil.

[0041] In the above embodiments of this application, such as Figure 2 As shown, the holographic optical element 12 can be, but is not limited to, implemented as a reflective holographic element to redirect reflected image light to converge in front of the pupil. In this way, the LBS optical engine 11 can be located inside the holographic optical element 12, i.e., the LBS optical engine 11 and the human eye are located on the same side of the holographic optical element 12, so that the LBS optical engine 11 can be arranged at the temple of the near-eye display device 1, simplifying the structural design of the near-eye display device 1.

[0042] Optionally, such as Figure 2 As shown, the LBS optical engine 11 includes a laser emitter 111 and a microelectromechanical mirror 112. The microelectromechanical mirror 112 is disposed on the emitting side of the laser emitter 111 and is used to scan the laser beam emitted by the laser emitter 111 to form image light that propagates to the image display area 102 of the holographic optical element 12.

[0043] It is worth noting that the laser emitter 111 mentioned in this application can be, but is not limited to, a laser diode (LD). Furthermore, during the scanning and image generation process, the LBS optomechanical system 11 of this application can achieve a change in the image center position by encoding the input image source information; and the angle of the center transmitted light corresponding to the image with the changed center position will also change after being scanned by the microelectromechanical galvanometer 112, thereby enabling the image display area 102 to move within the projection area 101.

[0044] Optionally, such as Figure 2 As shown, the LBS optical engine 11 further includes an achromatic lens 113, which is disposed in the optical path between the microelectromechanical mirror 112 and the holographic optical element 12, so that the image light scanned by the microelectromechanical mirror 112 first forms a real image in the optical path before the holographic optical element 12, and then is projected to the human eye for imaging via the holographic optical element 12.

[0045] Preferably, such as Figure 2 and Figure 3 As shown, the achromatic lens 113 mentioned in this application includes a first lens 1131 with positive optical power and a second lens 1132 with negative optical power, the first lens 1131 and the second lens 1132 being cemented together to form a cemented lens.

[0046] According to the above embodiments of this application, as Figure 1 and Figure 4 As shown, the near-eye display device 1 may further include an eye-tracking device 20 disposed on the device body 30 and used to track the pupil posture. The retinal projection device 10 is communicatively connected to the eye-tracking device 20 and is used to automatically adjust the image display position based on the pupil posture tracked by the eye-tracking device 20, ensuring that image light can pass through the pupil to form an image on the retina, thereby obtaining a near-eye display experience.

[0047] Thus, as Figure 4 As shown, when the eye-tracking device 20 detects a change in pupil posture (such as pupil position), the retinal projection device 10 can encode the image source information of the LBS optical engine 11 based on the pupil posture tracked by the eye-tracking device 20, so that the position of the image display area 102 formed by the LBS optical engine 11 on the holographic optical element 12 changes to correspond to the pupil position, and then the image light from the image display area 102 passes through the pupil to be imaged on the retina via the holographic optical element 12.

[0048] For example, such as Figure 1 and Figure 4 As shown, the eye-tracking device 20 may include an ET light source 21 and an ET camera 22 communicatively connected to the LBS optical engine 11. Both the ET light source 21 and the ET camera 22 are arranged around the holographic optical element 12. The ET light source 21 projects a light beam onto the eyeball. The ET camera 22 receives the light beam reflected from the eyeball to acquire a light spot image, and performs pupil tracking based on the light spot image to determine the pupil pose. It is understood that ET as mentioned in this application refers to eye tracking.

[0049] Optionally, such as Figure 1 As shown, the ET light source 21 includes multiple infrared LEDs 210 arranged in a ring around the holographic optical element 12, used to project infrared light onto the eyeball to avoid interference with near-eye display. Thus, because the multiple infrared LEDs 210 are arranged in a ring around the holographic optical element 12, a ring of light spots is formed on the eyeball. Therefore, when the eyeball moves to different positions, the ET camera 22 will capture images of different light spots to complete the capture of the pupil, thereby achieving high eye-tracking efficiency and improving human-computer interaction efficiency.

[0050] Accordingly, such as Figure 1 As shown, the ET camera 22 is implemented as an infrared camera 220 arranged toward the pupil, which facilitates direct reception of infrared light reflected by the eyeball for imaging, reducing interference from ambient light and image light on eye tracking.

[0051] Preferably, such as Figure 1As shown, the ET camera 22 includes a pair of infrared cameras 220 arranged at intervals to capture images of the pupil from different angles, so as to better cover the entire eyeball with the field of view.

[0052] It is worth mentioning that, in one modified embodiment of this application, such as Figure 5 As shown, the near-eye display device 1 may further include an interactive interface 40 disposed on the device body 30 and communicatively connected to the retinal projection device 10, for manually adjusting the image display position to ensure that the image light can pass through the pupil to form an image on the retina, thereby obtaining a near-eye display experience.

[0053] For example, the interactive interface 40 may, but is not limited to, be implemented as a knob. Thus, when the user observes that the displayed image is off to the right, the user can turn the knob to the left to send a signal to the retinal projection device 10 to adjust the image display position to the right. The retinal projection device 10 can then encode the image source information of the LBS optical engine 11 based on the signal to adjust the image display position to the right, so that the position of the image display area 102 formed by the LBS optical engine 11 on the holographic optical element 12 moves to the right to correspond to the position of the pupil, while still ensuring that the image light from the image display area 102 passes through the pupil and is imaged on the retina via the holographic optical element 12; and vice versa.

[0054] It is worth noting that the interactive interface 40 mentioned in this application can also be implemented as a button or a touch screen, as long as it can send an adjustment signal for the image display position to the retinal projection device 10 as needed. This application will not elaborate further on this.

[0055] 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.

[0056] The above embodiments are merely illustrative of several implementation methods of this application, and their descriptions are quite specific and detailed. However, they 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 modifications and improvements all fall within the protection scope of this application.

Claims

1. Retinal projection apparatus, characterized in that include: LBS optical engine, used to project image light; and A holographic optical element is disposed on the projection side of the LBS optical engine to focus the image light projected by the LBS optical engine in front of the pupil; The LBS optical engine forms a fixed projection area and a variable image display area within the projection area on the holographic optical element.

2. The retinal projection apparatus of claim 1, wherein, The distance between the convergence point formed by the holographic optical element and the pupil is between 5 mm and 15 mm.

3. The retinal projection apparatus of claim 1, wherein, The eye movement range of the retinal projection device is between 5mm and 10mm.

4. The retinal projection apparatus of claim 1, wherein, The eye-friendly distance range of the retinal projection device is between 15mm and 25mm.

5. The retinal projection apparatus of any one of claims 1 to 4, wherein, The holographic optical element is a reflective holographic element.

6. The retinal projection apparatus of any one of claims 1 to 4, wherein, The LBS optical engine includes a laser emitter and a microelectromechanical mirror (MEMS); the MEMS is disposed on the emitting side of the laser emitter.

7. The retinal projection apparatus of claim 6, wherein, The LBS optical engine further includes an achromatic lens, which is disposed in the optical path between the microelectromechanical mirror and the holographic optical element; The achromatic lens includes a first lens with positive optical power and a second lens with negative optical power, the first lens and the second lens being cemented together to form a cemented lens.

8. A near-eye display device, characterized by, include: Equipment body; and The retinal projection device as described in any one of claims 1 to 7 is disposed on the main body of the device.

9. The near-eye display device of claim 8, wherein, The near-eye display device further includes an interactive interface disposed on the main body of the device and communicatively connected to the retinal projection device; the interactive interface is a knob, button or touch screen.

10. The near-eye display device of claim 8, wherein, The near-eye display device further includes an eye-tracking device disposed on the main body of the device and communicatively connected to the retinal projection device; the eye-tracking device includes an ET light source and an ET camera; wherein the ET camera is communicatively connected to the LBS optical engine of the retinal projection device, and both the ET light source and the ET camera are arranged around the holographic optical elements of the retinal projection device.

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