A VR device

Abstract

The application discloses a VR device, comprising: a shell, and an optical module, an eye movement module and a display module located in the shell; the optical module comprises a lens barrel and a first lens, a second lens, a third lens and a fourth lens arranged in sequence along an optical axis from an object plane to an image plane in the lens barrel; the eye movement module is located between the first lens and the second lens; the eye movement module is provided with a light emitting unit and a receiving unit, the light emitting unit emits detection light which is reflected after passing through the object side surface and the image side surface of the first lens and then is incident to the receiving unit after being reflected on the object side surface of the second lens; the display module is located on the image side surface of the fourth lens, and the display module is used for displaying images. The overall structure of the VR device is ensured to be beautiful, the preparation cost is reduced, the imaging quality is improved, and the experience of users is ensured.

Description

Technical Field

[0001] This invention relates to the field of virtual display technology, and more particularly to a VR device. Background Technology

[0002] With the development of technology, virtual reality (VR) devices are widely used by users. In some fields such as games and movies, VR devices are used to simulate real scenes and bring a great experience.

[0003] To further enhance the user experience, eye-tracking modules are typically incorporated into virtual reality devices. Eye tracking tracks the movement of the human eye, understanding its trajectory and allowing the computer to determine where the user is looking. It shows promising application potential in autofocus technology within virtual reality devices.

[0004] However, in existing virtual reality devices, the eye-tracking module is usually placed on the outside of the virtual display device's casing, causing the overall structure to protrude in some areas, resulting in an asymmetrical overall structure, which affects the accuracy of eye tracking, while also increasing manufacturing costs and the overall aesthetics of the product. Summary of the Invention

[0005] This invention provides a VR device that ensures the overall aesthetic appeal of the VR device, reduces manufacturing costs, improves image quality, and guarantees a superior user experience.

[0006] This invention provides a VR device, including: a housing, and an optical module, an eye-tracking module, and a display module located inside the housing;

[0007] The optical module includes a lens barrel and a first lens, a second lens, a third lens, and a fourth lens arranged sequentially from the object plane to the image plane along the optical axis within the lens barrel.

[0008] The eye-tracking module is located between the first lens and the second lens; the eye-tracking module is provided with a light-emitting unit and a receiving unit. The light-emitting unit emits detection light to the human eye and then reflects it. The reflected detection light passes through the object side and image side of the first lens, and then is reflected by the object side of the second lens before entering the receiving unit.

[0009] The display module is located on the image-side side of the fourth lens, and the display module is used to display images.

[0010] Optionally, the VR device further includes an adjustment unit, which is movably connected to the housing and connected to the lens barrel. The adjustment unit is used to move the lens barrel to adjust the distance between the third lens and the fourth lens.

[0011] Optionally, the focal length of the second lens is FL2, and the focal length of the fourth lens is FL4, wherein FL2 > 0 and FL4 < 0.

[0012] Optionally, the radius of curvature of the object side surface of the second lens is R2, where 157.5≤R2≤318.5.

[0013] Optionally, the refractive index of the fourth lens is Nd, and the Abbe number is Vd, where Nd > 1.6 and Vd < 30.

[0014] Optionally, the object side of the second lens is provided with an infrared light reflecting film and a visible light anti-reflection film, and the image side of the fourth lens is provided with a semi-transparent and semi-reflective film.

[0015] Optionally, the optical module further includes an optical polarization conversion film, which is disposed between the second lens and the third lens.

[0016] Optionally, the distance from the center of the optical axis on the object side of the first lens to the image plane is TTL, where 19mm≤TTL≤32mm.

[0017] Optionally, the focal length of the first lens is FL1, and the effective focal length of the optical module is EFL, wherein 43.5mm≤FL1≤81.2mm, and 0.37<EFL / FL1<0.41.

[0018] Optionally, the field of view of the optical module is FOV, wherein FOV ≥ 90°.

[0019] The technical solution of this invention, through a VR device, includes: a housing, and an optical module, an eye-tracking module, and a display module located inside the housing; the optical module includes a lens barrel and a first lens, a second lens, a third lens, and a fourth lens arranged sequentially from the object plane to the image plane along the optical axis within the lens barrel; the eye-tracking module is located between the first lens and the second lens; the eye-tracking module is provided with a light-emitting unit and a receiving unit, the light-emitting unit emits detection light to the human eye and is reflected, the reflected detection light passes through the object-side and image-side of the first lens, is reflected again on the object-side of the second lens, and then enters the receiving unit; the display module is located on the image-side of the fourth lens, and the display module is used to display images. Changing the setting position of the eye-tracking module ensures the overall structural aesthetics of the VR device, reduces manufacturing costs, and at the same time, by collecting changes in the human eye through the eye-tracking module, combined with the parameter performance of each lens in the optical module, improves image quality and ensures a good user experience.

[0020] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the structure of a VR device provided in an embodiment of the present invention;

[0023] Figure 2 A schematic diagram of the optical path structure of a VR device provided in an embodiment of the present invention.

[0024] Figure 3 This is a schematic diagram of the optical path structure of an eye-tracking module provided in an embodiment of the present invention;

[0025] Figure 4 A vertical axis color difference diagram of a VR device provided in an embodiment of the present invention;

[0026] Figure 5 A field distortion diagram of a VR device provided in an embodiment of the present invention;

[0027] Figure 6 This invention provides an embodiment of a VR device with an MTF vs Field plot when the diopter is 0D.

[0028] Figure 7 This invention provides an MTF chart of a VR device at a diopter of 0D.

[0029] Figure 8 This invention provides an MTF chart of a VR device at a diopter of -3D.

[0030] Figure 9 The MTF diagram of a VR device with a diopter of -6D is provided in an embodiment of the present invention. Detailed Implementation

[0031] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0032] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0033] Figure 1 This is a schematic diagram of the structure of a VR device provided in an embodiment of the present invention. Figure 2 This is a schematic diagram of the optical path structure of a VR device provided in an embodiment of the present invention. Figure 3 This is a schematic diagram of the optical path structure of an eye-tracking module provided in an embodiment of the present invention, as shown below. Figure 1 , Figure 2 and Figure 3 As shown, the VR device 100 includes: a housing 101, and an optical module 102, an eye-tracking module 103, and a display module 104 located inside the housing 101; the optical module 102 includes a lens barrel 105 and a first lens 106, a second lens 107, a third lens 108, and a fourth lens 109 arranged sequentially from the object plane to the image plane along the optical axis inside the lens barrel 105; the eye-tracking module 103 is located between the first lens 106 and the second lens 107; the eye-tracking module 103 is provided with a light-emitting unit 110 and a receiving unit 111, the light-emitting unit 110 emits detection light to the human eye 10 and is reflected, the reflected detection light passes through the object side and the image side of the first lens 106 and is reflected by the object side of the second lens 107 before entering the receiving unit 111; the display module 104 is located on the image side of the fourth lens 109 and is used to display images.

[0034] The VR device 100 includes a housing 101, which houses and protects the optical module 102, the eye-tracking module 103, and the display module 104. The housing 101 may include a first housing portion 1011 for fixing the optical module 102 and the display module 104, and a second housing portion 1012 for supporting and fixing the eye-tracking module 103. The object plane is the plane where the human eye 10 is located, and the image plane is the plane where the display module 104 is located. The optical module 102 includes a lens barrel 105 and a first lens 106, a second lens 107, a third lens 108, and a fourth lens 109 arranged sequentially along the optical axis from the object plane to the image plane within the lens barrel 105. The surface of the lens adjacent to the object plane is the object-side surface, and the surface of the lens adjacent to the image plane is the image-side surface. For example, the image-side surface of the first lens 106 convexes towards the image plane; the second lens 107 can be a plano-convex lens with a flat object-side surface and an image-side surface convex towards the image plane; the image-side surface of the third lens 108 convexes towards the image plane; and the image-side surface of the fourth lens 109 convexes towards the image plane, with the object-side surface of the fourth lens 109 also convex towards the image plane. The image-side surface of the third lens 108 and the object-side surface of the fourth lens 109 can be fitted together, reducing the air gap between them, lowering chromatic aberration, and simultaneously reducing the overall length of the optical module 102, ensuring good imaging performance. The first lens 106, third lens 108, and fourth lens 109 can all be plastic lenses, and the second lens 107 can be either a plastic lens or a glass lens. An all-plastic optical module 102 can reduce manufacturing costs and device weight, while a hybrid glass-plastic optical module 102 can further improve its optical performance. Specific material selection can be made according to actual design requirements, and this embodiment of the invention does not impose specific limitations. The lens barrel 105 can be movably connected to the housing 101, facilitating the movement of the optical module 102 and enabling adjustable focusing of the VR device 100. Compared to traditional eye-tracking modules located on the outside of the housing 101 of the VR device 100, since the first lens 106 and the second lens 107 are spaced apart along the optical axis, this invention places the eye-tracking module 103 between the first lens 106 and the second lens 107, embedding the eye-tracking module 103 within the housing 101, thus maintaining the overall aesthetics of the VR device 100. The eye-tracking module 103 includes a light-emitting unit 110 and a receiving unit 111. The light-emitting unit 110 can be an infrared light-emitting diode, used to emit infrared detection light to the human eye 10. Two light-emitting units 110 can be provided, corresponding to the left and right eyes of the human eye 10, respectively. The receiving unit 111 can be an infrared light sensor, used to receive the detection light reflected by the human eye 10. Only one receiving unit 111 can be provided, fixed to any one of the light-emitting units 110. For example, two light-emitting units 110 are provided, and one receiving unit 111 is provided. The receiving unit 111 is provided on the light-emitting unit 110 on the right side.The light emitting unit 110 emits a detection light beam, which is reflected after reaching the human eye 10. The reflected detection light beam passes sequentially through the object-side and image-side surfaces of the first lens 106 and then enters the object-side surface of the second lens 107. After being reflected again by the object-side surface of the second lens 107, the detection light beam enters the receiving unit 111, which receives the detection light beam. Since the human eye 10 is moving, the angle of the detection light beam received by the receiving unit 111 is unknown, thus enabling it to track the human eye 10. The display module 104 is located on the image-side surface of the fourth lens 109 and is used to display images. When the user wears the VR device 100, the displayed image is projected onto the human eye 10 via the optical module 102 to ensure a good viewing experience. Since the eye-tracking module 103 and the optical module 102 are both housed in the housing 101, and the object side of the second lens 107 reflects the infrared detection light used by the eye-tracking module 103, the infrared detection light will not be emitted through the second lens 107 to the third lens 108. Only visible light can penetrate the second lens 107. Therefore, the eye-tracking module 103 can track the human eye 10 and the user can view the displayed image normally without interfering with each other, ensuring the normal operation of the VR device 100 and the user's experience. The eye-tracking module 103 includes a lamp plate located on the backlight side of the light-emitting unit 110, a light-transmitting plate located on the light-emitting side of the light-emitting unit 110, and a reinforcing plate located on the lamp plate. The lamp plate is used to supply power to the light-emitting unit 110 to ensure its normal operation. The lamp plate can be thin and can be a flexible circuit board 411, made of polyimide or polyester film as the substrate. It is a printed circuit board with good flexibility, light weight, and thinness, which is convenient to match the spatial shape between the first lens 106 and the second lens 107. Its specific shape can be designed according to the spatial shape between the first lens 106 and the second lens 107. The lamp plate 11 can be fixed to the housing 101 by means of adhesive or bolt connection. The light-transmitting plate 12 is used to filter the detection light emitted by the light-emitting unit 110, so that infrared light of a fixed wavelength can pass through the light-transmitting plate 12 and enter the human eye 10. The reinforcing plate 13 can be used to increase the strength of the light panel 11. Multiple reinforcing plates 13 can be set to protect the light panel 11. The VR device 100 is matched with the pupil range of the corresponding human eye 10, which is 4-8mm, to ensure that most users can use the VR device 100 normally.

[0035] This invention employs a first lens, a second lens, a third lens, and a fourth lens within an optical module to adjust light, ensuring imaging quality and a superior user experience. Simultaneously, the eye-tracking module is integrated into the housing and positioned between the first and second lenses, guaranteeing accurate reception of the detection light reflected from the human eye while maintaining the aesthetically pleasing overall structure of the VR device and reducing manufacturing costs.

[0036] Optional, continue to refer to Figure 1 The VR device 100 also includes an adjustment unit 112, which is movably connected to the housing 101 and connected to the lens barrel 105. The adjustment unit 112 is used to move the lens barrel 105 to adjust the distance between the third lens 108 and the fourth lens 109.

[0037] The adjustment unit 112 can be a focusing component, which can adjust the optical module 102 according to the human eye tracking results output by the eye-tracking module 103. By affecting the focusing effect of the optical module 102, it can affect the viewing effect of the user when wearing the VR device 100, thereby improving the user's experience. The adjustment unit 112 is installed on the outer wall of the lens barrel 105. The adjustment unit 112 is movably connected to the housing 101. At the same time, the fourth lens 109 is fixed inside the lens barrel 105. Moving the adjustment unit 112 can drive the fourth lens 109 to move, thereby affecting the relative positional relationship between the fourth lens 109 and the third lens 108. This allows for adjustment of the distance between the fourth lens 109 and the third lens 108, affecting the refractive power of the optical module 102. The adjustable range of the refractive power is 0D to -6D. The unit of refractive power is diopter. The stronger the refractive power, the shorter the focal length; the weaker the refractive power, the longer the focal length. The specific refractive power is selected according to the uncorrected visual acuity requirements of different users. By adjusting the distance between the third lens 108 and the fourth lens 109, the optical module 102 can effectively meet the uncorrected visual acuity requirements of different users, improving the imaging effect.

[0038] Optional, continue to refer to Figure 1 , Figure 2 and Figure 3 The focal length of the second lens 107 is FL2, and the focal length of the fourth lens 109 is FL4, where FL2 > 0 and FL4 < 0.

[0039] The second lens 107 has a positive focal length and the fourth lens 109 has a negative focal length. By making reasonable use of each lens and allocating the focal length of each lens, it is beneficial to correct aberrations, reduce the distortion of the optical module 102, ensure that the optical module 102 has high resolution, and thus ensure the imaging effect.

[0040] Optional, continue to refer to Figure 1 , Figure 2 and Figure 3 The radius of curvature of the object side surface of the second lens 107 is R2, where 157.5≤R2≤318.5.

[0041] The unit of curvature radius is millimeters (mm). By setting the curvature radius R2 of the object side surface of the second lens 107 to satisfy 157.5≤R2≤318.5, the curvature of the object side surface of the second lens 107 is controlled. This is beneficial for the detection light emitted from the light-emitting unit 110 of the eye-tracking module 103 to be reflected by the object side surface of the second lens 107 and then received by the receiving unit 111 of the eye-tracking module 103, thereby realizing the tracking of the human eye 10. At the same time, by optimizing the shape of the second lens 107, the imaging quality of the optical module 102 is improved, ensuring the overall optical performance of the VR device 100.

[0042] Optionally, the refractive index of the fourth lens 109 is Nd, and the Abbe number is Vd, where Nd > 1.6 and Vd < 30.

[0043] The refractive index is the ratio of the speed of light in a vacuum to the speed of light in the medium, primarily used to describe a material's ability to refract light; different materials have different refractive indices. The Abbe number is an index used to represent the dispersion ability of a transparent medium; the more severe the dispersion, the smaller the Abbe number; conversely, the less severe the dispersion, the larger the Abbe number. Thus, by adjusting the refractive index and Abbe number of the fourth lens 109 in the optical module 102, the adjustment of the light incident on the fourth lens 109 is ensured, maintaining a balance in the incident angle between adjacent lenses, reducing lens sensitivity, improving production feasibility, and simultaneously ensuring the field of view of the optical module 102, thereby guaranteeing the optical performance of the VR device 100.

[0044] Optional, continue to refer to Figure 1 , Figure 2 and Figure 3 The object side of the second lens 107 is provided with an infrared light reflective film and a visible light anti-reflective film, and the image side of the fourth lens 109 is provided with a semi-transparent and semi-reflective film.

[0045] To further ensure the tracking effect of the eye-tracking module 103 on the human eye 10, an infrared light reflective film and a visible light anti-reflective film can be provided on the object-side surface of the second lens 107. This allows the detection light emitted from the light-emitting unit 110 of the eye-tracking module 103 to pass through the first lens 106 and then onto the object-side surface of the second lens 107. The light is then emitted through the infrared light reflective film on the object-side surface and subsequently reaches the receiving unit 111 of the eye-tracking module 103. This ensures that the detection light reaches the receiving unit 111 as much as possible, completing the tracking of the human eye 10 by the eye-tracking module 103. This provides accurate data for subsequent focusing, ensuring the optical performance of the VR device 100 and improving the user experience. Simultaneously, the visible light anti-reflective film on the object-side surface of the second lens 107 ensures that visible light can pass through the second lens 107 normally and then reach the third lens 108 and the fourth lens 109. Meanwhile, a semi-transparent and semi-reflective film is provided on the image side of the fourth lens 109, which can ensure that 50% of the light emitted from the fourth lens 109 can pass through the image side of the fourth lens 109 and 50% can be reflected by the image side of the fourth lens 109. The film structure on the lens is reasonably set according to the design requirements to further improve the optical performance of the VR device 100.

[0046] Optional, continue to refer to Figure 1 , Figure 2 and Figure 3 The optical module 102 also includes an optical polarization conversion film 113, which is disposed between the second lens 107 and the third lens 108.

[0047] An optical polarization conversion film 113 is disposed between the second lens 107 and the third lens 108. Light rays exiting from the image side of the second lens 107 are polarized by the optical polarization conversion film 113 and then incident on the object side of the third lens 108. After being reflected by the image side of the fourth lens 109, which is equipped with a semi-transparent and semi-reflective film, the light rays are polarized again by the optical polarization conversion film 113 and then incident on the image side of the second lens 107. Light rays exiting from the image side of the second lens 107 are incident on the object side of the third lens 108 and then exit from the image side of the fourth lens 109. Through multiple reflections of light between the image side of the second lens 107, the optical polarization conversion film 113, and the fourth lens 109, the divergence angle of the light rays is changed, thereby matching the field of view of the optical module 102 and ensuring the optical performance of the VR device 100.

[0048] Optional, continue to refer to Figure 1 , Figure 2 and Figure 3 The distance from the center of the optical axis on the object side of the first lens 106 to the image plane is TTL, where 19mm≤TTL≤32mm.

[0049] Optionally, the focal length of the first lens 106 is FL1, and the effective focal length of the optical module 102 is EFL, wherein 43.5mm≤FL1≤81.2mm, and 0.37<EFL / FL1<0.41.

[0050] The distance TTL from the center of the optical axis on the object side of the first lens 106 to the image plane can be understood as the total length of the optical module 102. The effective focal length EFL of the optical module 102 can be understood as the distance between the center of the optical module 102 and the focal point of the optical module 102. The effective focal length EFL of the optical module 102 is between 18 and 30 mm. By reasonably setting the total length of the optical module 102 and the relationship between the effective focal length of the optical module 102 and the focal length of the first lens 106, the entire optical module 102 can be ensured to have a compact structure and high integration. At the same time, the optical performance of the VR device 100 can be further improved, ensuring the imaging effect and enhancing the user experience.

[0051] Optional, continue to refer to Figure 1 , Figure 2 and Figure 3 The field of view of the optical module 102 is FOV, where FOV > 90°.

[0052] The optical module 102 provided in this embodiment of the invention is a large field-of-view optical module 102, which meets the requirements of a large field of view and thus improves the user experience.

[0053] Figure 4 A vertical axis chromatic aberration diagram of a VR device provided in an embodiment of the present invention, such as... Figure 4 As shown, the vertical direction represents the normalized field of view, with 0 indicating the optical axis and the vertical vertex representing the maximum field radius; the horizontal direction represents the offset within the 0.587μm meridional range, in μm. The numbers on the curves in the figure represent the wavelengths represented by the curves, in μm. As can be seen from Figure X, the chromatic aberration along the vertical axis can be controlled within the range of (-2μm, 16μm).

[0054] Figure 5 A field distortion diagram of a VR device provided in an embodiment of the present invention, such as... Figure 5 As shown, in the coordinate system on the left, the horizontal coordinate represents the magnitude of the field curvature, in mm; the vertical coordinate represents the normalized image height, which has no unit; where T represents the meridion and S represents the arc loss; from Figure 5 It can be seen that the VR device 100 provided in this embodiment effectively controls the field curvature of light from wavelengths of 486nm to 656nm, meaning that during imaging, the difference in image quality between the center and the periphery is small; in the coordinate system on the right, the horizontal axis represents the magnitude of distortion, expressed as a percentage; the vertical axis represents the normalized image height, which has no unit; from Figure 5As can be seen, the distortion of the VR device 100 provided in this embodiment of the invention has been well corrected, the imaging distortion is small, and the requirement of low distortion is met.

[0055] Figure 6 An MTF vs Field diagram of a VR device at a diopter of 0D is provided as an embodiment of the present invention. Figure 6 As shown, in the two different modes of 15 line pairs / mm and 20 line pairs / mm, the distance between its sagittal curve and meridional curve is relatively close, the lens has less astigmatism, and each curve is relatively smooth with little fluctuation, resulting in high image uniformity and meeting the requirements for good image quality.

[0056] Figure 7 An MTF chart of a VR device at a diopter of 0D is provided as an embodiment of the present invention, such as Figure 7 As shown, the transfer function of the MTF curve at 15 line pairs / mm is generally above 0.4, which can meet the requirements for good image quality.

[0057] Figure 8 An MTF chart of a VR device at a diopter of -3D is provided as an embodiment of the present invention, such as Figure 8 As shown, the transfer function of the MTF curve at 15 line pairs / mm is generally above 0.4, which can meet the requirements for good image quality.

[0058] Figure 9 An MTF chart of a VR device at a diopter of -6D is provided as an embodiment of the present invention. Figure 9 As shown, the transfer function of the MTF curve at 15 line pairs / mm is generally above 0.2, which can meet the requirements for good image quality.

[0059] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A VR device, characterized in that, include: The housing, and the optical module, eye-tracking module and display module located inside the housing; The optical module includes a lens barrel and a first lens, a second lens, a third lens, and a fourth lens arranged sequentially from the object plane to the image plane along the optical axis within the lens barrel. The eye-tracking module is located between the first lens and the second lens; the eye-tracking module is provided with a light-emitting unit and a receiving unit. The light-emitting unit emits detection light to the human eye and then reflects it. The reflected detection light passes through the object side and image side of the first lens, and then is reflected by the object side of the second lens before entering the receiving unit. The display module is located on the image-side side of the fourth lens, and the display module is used to display images; The object side of the second lens is provided with an infrared light reflecting film and a visible light anti-reflection film; The focal length of the first lens is FL1, and the effective focal length of the optical module is EFL, wherein 43.5mm≤FL1≤81.2mm, and 0.37<EFL / FL1<0.

41.

2. The VR device according to claim 1, characterized in that, The VR device also includes an adjustment unit, which is movably connected to the housing and connected to the lens barrel. The adjustment unit is used to move the lens barrel to adjust the distance between the third lens and the fourth lens.

3. The VR device according to claim 1, characterized in that, The focal length of the second lens is FL2, and the focal length of the fourth lens is FL4, wherein FL2 > 0 and FL4 < 0.

4. The VR device according to claim 1, characterized in that, The radius of curvature of the object side surface of the second lens is R2, where 157.5≤R2≤318.

5.

5. The VR device according to claim 1, characterized in that, The fourth lens has a refractive index of Nd4 and an Abbe number of Vd4, where Nd4 > 1.6 and Vd4 < 30.

6. The VR device according to claim 1, characterized in that, The image-side surface of the fourth lens is provided with a semi-transparent and semi-reflective coating.

7. The VR device according to claim 1, characterized in that, The optical module also includes an optical polarization conversion film, which is disposed between the second lens and the third lens.

8. The VR device according to claim 1, characterized in that, The distance from the center of the optical axis on the object side of the first lens to the image plane is TTL, where 19mm≤TTL≤32mm.

9. The VR device according to claim 1, characterized in that, The field of view of the optical module is FOV, where FOV ≥ 90°.

Images