VR optical module and electronic device

Abstract

Embodiments of the present application provide a VR optical module and an electronic device. The VR optical module comprises: a display screen, the display screen having opposite front and back surfaces and extending along a first direction; and a lens array, the lens array being spaced apart from the front surface of the display screen and comprising a plurality of self-focusing lenses arranged along the first direction. At least the overall thickness of the optical module is reduced, the total length of the VR device is reduced, and the imaging quality and application prospect of the VR device are improved.

Description

Technical Field

[0001] This application relates to the field of optical technology, and in particular to a VR optical module and electronic device. Background Technology

[0002] With the rapid development of electronic manufacturing technology, various types of electronic products have been widely used. VR (Virtual Reality) uses computers to create a three-dimensional virtual world, providing users with interactive scenes of sight, touch, and hearing, allowing users to feel as if they are there and immerse themselves in the virtual world. At the same time, they can observe things in three-dimensional space and interact with them.

[0003] The optical system is a crucial component of VR devices, typically comprising lenses and a display screen. It provides users with an immersive virtual experience. Fresnel lenses are widely used in VR devices due to their small size and relatively low cost, reducing system size and cost. However, current VR devices suffer from poor image quality, a narrow field of view, and excessive overall length, resulting in a subpar user experience. Summary of the Invention

[0004] The purpose of some embodiments of this application is to provide a VR optical module and electronic device, which at least helps to reduce the overall thickness of the optical module, reduce the total length of the VR device, and improve the imaging quality and application prospects of the VR device.

[0005] To at least solve the above-mentioned technical problems, some embodiments of this application provide a VR optical module, including: a display screen having a front and a back side facing each other and extending along a first direction; a lens array spaced apart from the front side of the display screen, and the lens array including a plurality of self-focusing lenses arranged along the first direction.

[0006] In some embodiments, the display screen is a curved screen.

[0007] In some embodiments, the central angle corresponding to the arc formed by the display screen along the first direction is 110° to 180°.

[0008] In some embodiments, the distance between the back side of the display screen and the side of the lens array away from the display screen is 0 mm to 10 mm in a direction perpendicular to the front side of the display screen.

[0009] In some embodiments, each of the plurality of self-focusing lenses has a circular, elliptical, or polygonal cross-section along a direction perpendicular to the extension.

[0010] In some embodiments, the lens array further includes at least two microlenses located on different side edges of the array; the angle formed by the line connecting any two microlenses located on different sides of the at least two microlenses and the observation point of the VR optical module is 110° to 180°.

[0011] In some embodiments, the central refractive index of each of the plurality of self-focusing lenses is 1.5 to 2.0.

[0012] In some embodiments, the maximum step size of the self-focusing lens is 0 to 99.

[0013] In some embodiments, the focal length of the self-focusing lens is 2 mm to 25 mm.

[0014] Correspondingly, some embodiments of this application also provide an electronic device, including the VR optical module described above.

[0015] In the technical solution provided in this application embodiment, during the construction of the VR optical module, a self-focusing lens is used to construct a lens array that is positioned directly opposite the display screen. By utilizing the characteristics of the self-focusing lens, a good display effect is achieved while effectively reducing the total thickness of the lens array, thereby significantly reducing the thickness of the final VR optical module and VR device. At the same time, when a self-focusing lens is used to construct the lens array, the lens array consists of multiple flat-plate lenses, which facilitates the assembly and positioning of the lens array, improves the production and maintenance efficiency of the VR optical module, and thus enhances the application prospects of the VR optical module. Attached Figure Description

[0016] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0017] Figure 1 This is a schematic diagram of the structure of a VR optical module according to an embodiment of this application;

[0018] Figure 2 This is a schematic diagram illustrating the working principle of a self-focusing lens according to an embodiment of this application;

[0019] Figure 3 This is a schematic diagram of another VR optical module provided according to an embodiment of this application;

[0020] Figure 4 This is a schematic diagram of the structure of another VR optical module provided according to an embodiment of this application;

[0021] Figure 5 This is a schematic diagram illustrating the performance simulation results of a self-focusing lens according to an embodiment of this application;

[0022] Figure 6 This is a schematic diagram of the performance simulation structure of another self-focusing lens provided according to an embodiment of this application. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the various embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details are presented in the various embodiments of the present invention to facilitate a better understanding of this application. However, the technical solutions claimed in this application can be implemented even without these technical details and various changes and modifications based on the following embodiments. The division of the various embodiments below is for ease of description and should not constitute any limitation on the specific implementation of the present invention. The various embodiments can be combined with and referenced by each other without contradiction.

[0024] The implementation details of the VR optical module described in this application will be specifically described below with reference to specific embodiments. The following implementation details are provided for ease of understanding only and are not necessary for implementing this solution.

[0025] A first aspect of the embodiments of this application provides a VR optical module, referencing... Figure 1 , Figure 1 The image shows a top view of a VR optical module, which includes a display screen 100 and a lens array 200. The display screen 100 has a front and a back facing each other and extends along a first direction. The lens array 200 is spaced apart from the front of the display screen 100, and the lens array 200 includes a plurality of self-focusing lenses 210 arranged along the first direction, wherein the X direction is the first direction.

[0026] refer to Figure 1 and Figure 2 One of the inherent properties of light is that, during its propagation through air, light changes its direction of propagation due to the different refractive indices of different media. The principle of the self-focusing lens 210 in converging outgoing light rays is similar to this property. The material of the self-focusing lens 210 allows axially propagating light rays to be refracted, and the refractive index distribution gradually decreases radially, thus enabling the outgoing light rays to be smoothly and continuously converged to a single point. In constructing the lens array 200 using the self-focusing lens 210, after determining the observation point b (i.e., the position of the user's eye during use), the convergence point of the outgoing light rays from each focusing lens 210 within the lens array 200 is set as observation point b by adjusting the parameters and placement angles of each focusing lens 210.

[0027] In the process of constructing the VR optical module, multiple self-focusing lenses 210 arranged along the first direction are used to construct the lens array 200. Since the total thickness of the VR optical module is mainly determined by the thickness of the lens array 200, and the self-focusing lens 210 can converge the incident light to a single point for emission within a short optical path, the overall thickness of the lens array 200 is greatly reduced when using the self-focusing lens 210, thereby reducing the thickness of the VR optical module. At the same time, due to the light transmission characteristics of the self-focusing lens 210, the emitted light can be smoothly and continuously converged to a specified point, giving the VR optical module a good imaging effect. The self-focusing lens 210 has a flat plate structure, so the assembly and positioning difficulty of the lens array 200 constructed using the self-focusing lens 210 is greatly reduced, improving the production and maintenance efficiency of the VR optical module, and thus improving the application prospects of the VR optical module.

[0028] It should be understood that during the construction of the lens array 200, in order to ensure that the light rays emitted from each focusing lens 210 can all converge to the observation point b, since the size, shape, and placement angle of each focusing lens 210 can be the same or different, in specific applications, the specifications and placement of the selected self-focusing lens 210 can be adjusted according to the convergence requirements of the emitted light rays. This application embodiment does not limit this.

[0029] refer to Figures 1 to 3 In some embodiments, the display screen 100 is a curved screen. Figure 3 This is a schematic diagram of the structure of a VR optical module consisting of a curved screen and a lens array 210, where the Y direction is the first direction.

[0030] In the construction of the VR optical module, the display screen 100 serves as the light source, and its shape and placement determine the user's field of view. To further enhance the immersion and realism of the VR device, a curved screen extending along an arc can be used as the display screen 100. This allows the distribution of incident light received by the VR optical module to more closely match the light distribution perceived by the human eye, thereby making the user's field of view more closely match the field of view perceived by the human eye, improving the realism during use, and ultimately enhancing the user experience.

[0031] In some embodiments, the central angle corresponding to the arc a formed by the display screen 100 along the first direction is 110° to 180°.

[0032] VR devices typically contain two VR optical modules, each corresponding to one eye. Under normal circumstances, the human eye's monocular field of view is typically 124° to 156°, while the binocular field of view can reach 188°. Therefore, in the design and manufacturing of VR optical modules, using a curved screen as the display 100 can effectively improve the match between the light source of the lens array 200 in the VR optical module and the actual light source of the human eye.

[0033] During the selection of display screen 100, the line connecting the two endpoints of arc a corresponding to display screen 100 and observation point b can be equivalently regarded as the field of view when the user views display screen 100 through the VR optical module. Therefore, if the central angle corresponding to arc a is too small, the field of view when the user views the screen content using the VR optical module is much smaller than the actual field of view of the human eye, resulting in poor imaging effect and poor user immersion. If the central angle corresponding to arc a is too large, the field of view when the user views the screen content using the VR optical module is much larger than the actual field of view of the human eye, resulting in some wasted display performance and a significant increase in the manufacturing cost of the VR optical module.

[0034] Therefore, when selecting the display screen 100, the central angle corresponding to the arc a of the display screen 100 can be set within the range of 110° to 180°. For example, the central angle corresponding to the arc a can be set to 115°, 120°, 135°, 150°, 155°, 160°, 170°, or 175°. By setting the central angle corresponding to the arc a of the display screen 100 within a suitable range, the field of view of the content displayed in the VR optical module is ensured to be as close as possible to the actual field of view of the human eye. This guarantees imaging effect and user experience while reducing the design and manufacturing cost of the VR optical module and avoiding excessive display performance redundancy.

[0035] Furthermore, it's important to understand that during the convergence of emitted light using the lens array 200, the poor imaging effect of the lens array 200 on the content at the edge of the display screen 100 results in image gaps. The actual field of view of the content observed by the user through the VR optical module is smaller than the original field of view of the display screen 100. Therefore, when configuring the display screen 100, the original field of view of the display screen 100, i.e., the central angle corresponding to arc a of the display screen 100, can be set slightly larger than the field of view of the human eye. For example, the central angle of arc a corresponding to the display screen 100 can be set to an angle 5° to 15° larger than the monocular field of view of the human eye, reserving space for the loss of field of view, thereby further improving the imaging effect of the VR optical module.

[0036] In some embodiments, the distance between the back side of the display screen 100 and the side of the lens array 200 away from the display screen 100 in a direction perpendicular to the front side of the display screen 110 is 0 mm to 10 mm.

[0037] During the construction of VR optical modules, it is necessary to limit the thickness of the VR optical modules to achieve the goal of forming ultra-thin VR lenses. The thickness of the VR optical module can be equivalently regarded as the interval between the side of the display screen 100 away from the lens array 200 and the side of the lens array 200 away from the display screen 100, that is, the interval between the back of the display screen 100 and the side of the lens array 200 away from the display screen 100.

[0038] If the VR optical module is too thick, the VR lens of the VR device will be too thick, making it impossible to achieve an ultra-thin VR device. Furthermore, an excessively thick VR lens will significantly reduce user convenience and hinder application prospects. If the VR optical module is too thin, the self-focusing lens 210 included in the lens array 200 will be too small, resulting in weak light-gathering ability. This will prevent the light generated by the display screen 100 from being smoothly and continuously focused onto the observation point b, leading to poor imaging capabilities and a bad user experience.

[0039] Therefore, during the construction of the VR optical module, the thickness of the VR optical module, specifically the distance between the back of the display screen 100 and the side of the lens array 200 away from the display screen 100 along the direction perpendicular to the front of the display screen 100, can be set within the range of 0mm to 10mm. For example, the thickness of the VR optical module can be set to 0.5mm, 1mm, 2mm, 3.5mm, 5mm, 6mm, 8mm, or 9mm. By setting the thickness of the VR optical module within a suitable range, the thickness of the VR lens can be significantly reduced while ensuring the imaging capability and user experience of the VR optical module.

[0040] It is worth mentioning that the display screen 100 can be a flat screen or a curved screen, and the lens array 200 can be arranged in an arc or a line. The distance between the back of the display screen 100 and the side of the lens array 200 away from the display screen 100 can be understood as the distance between any point on the back of the display screen 100 and the intersection of the normal line passing through that point and the surface of the lens array 200 away from the display screen 100.

[0041] In some embodiments, each of the plurality of self-focusing lenses 210 has a circular, elliptical, or polygonal cross-section along the direction perpendicular to the extension.

[0042] In the process of constructing the lens array 200, multiple self-focusing lenses 210 of the same shape and specifications can be used to construct the lens array 200, or multiple self-focusing lenses 210 of different shapes and specifications can be used to construct the lens array 200. In the process of selecting the self-focusing lens 210, the self-focusing lens 210 can be selected from cylindrical or prismatic self-focusing lenses 210 according to the requirements of cross-sectional area, arrangement requirements and size of the self-focusing lens 210. Thus, self-focusing lenses 210 with a cross-section of circular, elliptical or polygonal along the extension direction can be selected to construct the lens array 200, thereby improving the application scenarios of VR optical modules.

[0043] It is important to understand that the extension direction of the self-focusing lens 210 refers to the overall transmission direction of the light rays on the display screen 100 as they travel through the self-focusing lens 210 to the observation point b.

[0044] refer to Figures 1 to 4 In some embodiments, the lens array 200 further includes at least two microlenses 220 located on different side edges of the array; the angle formed by the line connecting any two of the at least two microlenses 220 located on different sides to the observation point b of the VR optical module is between 110° and 180°.

[0045] During the construction of the lens array 200, the self-focusing lens 210 has a certain upper limit to its ability to converge light from the edge area of ​​the display screen 100. In the VR optical module, if the central angle corresponding to the arc a of the display screen 100 is too large, the self-focusing lens 210 cannot adequately converge the light from the edge area of ​​the display screen 100, resulting in insufficient image quality in the edge area and a poor user experience. However, the microlens 220, thanks to its own light-converging mechanism, has excellent light-converging capability during the transmission of light from the edge area of ​​the curved screen.

[0046] Therefore, when the central angle corresponding to arc a of display screen 100 is greater than 110°, during the construction of lens array 200, multiple self-focusing lenses 210 are set in the central region of lens array 200, and at least one microlens 220 is set in each of the two edge regions along the extension direction of lens array 200. This ensures that the angle formed by the lines connecting any two microlenses 220 on different edges of lens array 200 to the observation point b of the VR optical module is within the range of 110° to 180°. For example, the angle formed by the lines connecting the microlenses 220 on different edges to the observation point b can be 115°, 120°, 135°, 150°, 170°, or 175°. When the central angle corresponding to arc a of display screen 100 is too large, the lens array 200, constructed using microlenses 220 in the edge region and self-focusing lenses 210 in the central region, ensures the imaging quality of the VR optical module for the content in the edge region of display screen 100, thus improving the user experience.

[0047] It is worth mentioning that the number of microlenses 220 set on different side edges can be the same or different, and the specifications and shapes of the microlenses 220 used can be the same or different. This application embodiment does not limit this.

[0048] In some embodiments, the central refractive index of each of the plurality of self-focusing lenses 210 is 1.5 to 2.0.

[0049] The central refractive index of the self-focusing lens 210 reflects its ability to smoothly and continuously converge outgoing light rays to a single point. When constructing the lens array 200 using the self-focusing lens 210, under otherwise identical conditions, a higher central refractive index allows the self-focusing lens 210 to converge outgoing light rays to the same point within a shorter optical path. If the central refractive index of the self-focusing lens 210 is too low, the distance required for the lens array 200 to converge the outgoing light rays to the same point is too large, resulting in an excessively large gap between the VR optical module and the observation point, preventing an effective reduction in the overall thickness of the VR device. Conversely, if the central refractive index of the self-focusing lens 210 is too high, the distance required for the lens array 200 to converge the outgoing light rays to the same point is very small, resulting in excessively strong light convergence. Continuous changes in light can easily exceed the human eye's recognition limit, leading to some content being unrecognizable and a poor user experience.

[0050] Therefore, during the construction of the lens array 200 using the self-focusing lens 210, the central refractive index of the self-focusing lens 210 is controlled within the range of 1.5 to 2.0. For example, the central refractive index of the self-focusing lens 210 can be set at 1.55, 1.6, 1.7, 1.85, 1.9, or 1.95. By setting the central refractive index of the self-focusing lens 210 within a suitable range, the self-focusing lens 210 is guaranteed to have good light-gathering ability. This achieves the goal of reducing the overall thickness of the VR device containing the VR optical module, while avoiding the VR optical module's excessive optical gathering ability from causing some content to be unreceived by the human eye, thus ensuring a good user experience.

[0051] It is worth mentioning that among the multiple self-focusing lenses 210 used to construct the lens array 200, the central refractive index of each focusing lens 210 can be the same or different, and this application embodiment does not impose any restrictions on this.

[0052] In some embodiments, the maximum step size of the self-focusing lens 210 is 0 to 99.

[0053] The light-gathering capability of the self-focusing lens 210 is also related to its maximum step size. The maximum step size determines the relationship between the speed and accuracy of ray tracing; the smaller the maximum step size, the higher the accuracy of ray tracing. Taking gradient 9 as an example, when the maximum step size is 0.01 or even lower, the light trajectory is closer to the ideal sinusoidal distribution. When the maximum step size is 1 or even larger, the light trajectory is approximately a straight line. When the maximum step size is too large, the light-gathering capability of the self-focusing lens 210 is too weak. In order to converge the outgoing light rays to the same point, the length of the self-focusing lens 210 along the extension direction is large, which in turn leads to a large overall thickness of the VR optical module.

[0054] Therefore, in constructing the lens array 200 using the self-focusing lens 210, the maximum step size of each selected focusing lens 210 can be set within the range of 0 to 99, for example, 0.5, 1, 2.5, 5, 10, 15, 25, 40, 55, 75, 90, or 95. By setting the maximum step size of the self-focusing lens 210 within a suitable range, the self-focusing lens 210 is guaranteed to have good light-gathering ability, thereby effectively shortening the overall thickness of the VR optical module.

[0055] In some embodiments, the focal length of the self-focusing lens 210 is 2 mm to 25 mm.

[0056] Focal length refers to the distance from the optical center of the lens to the focal point where parallel light converges when parallel light is incident during the light-converging process of the self-focusing lens 210. The smaller the focal length, the stronger the light-converging ability of the self-focusing lens 210. If the focal length of the self-focusing lens 210 is too small, the light-converging ability of the lens array 200 will be too strong, and continuous changes in light may easily exceed the recognition limit of the human eye, resulting in some content being unrecognizable to the human eye and a poor user experience. If the focal length of the self-focusing lens 210 is too large, the light-converging ability of the lens array 200 will be too weak, and the overall thickness of the VR device cannot be effectively reduced.

[0057] Therefore, during the construction of the lens array 200, the focal length of the self-focusing lens 210 is controlled within the range of 2mm to 25mm. For example, the focal length of the self-focusing lens 210 can be set to 2.5mm, 3mm, 5mm, 10mm, 15mm, 18.5mm, 20mm, 22mm, or 24mm. By controlling the focal length of the self-focusing lens 210 within a suitable range, while ensuring that the self-focusing lens 210 has good light-gathering ability and minimizing the overall thickness of the VR optical module, content transmission loss due to excessive light-gathering ability of the VR optical module is avoided as much as possible, thus ensuring a good user experience.

[0058] Through simulation in optical product design and simulation software (hereinafter referred to as Zemax design software), the self-focusing lens 210 can achieve the same optical performance as a microlens of the same specifications. Zemax design software offers 10 definition methods for the self-focusing lens 210. Taking Gradient 5 as an example, the parameter definition table for Gradient 5 can be found in Table 1:

[0059] Where Δt is the maximum step size, which determines the relationship between the speed and accuracy of ray tracing; n0 is the central refractive index; nr2 is the first refractive index coefficient along the radial direction; nr4 is the second refractive index coefficient along the radial direction; nz1 is the first refractive index coefficient along the axial direction; nz2 is the second refractive index coefficient along the axial direction; nz3 is the third refractive index coefficient along the axial direction; nz4 is the fourth refractive index coefficient along the axial direction; tanα is the tangent at the x-angle of inclination; and tanβ is the tangent at the y-angle of inclination.

[0060] Parameter Definition 1 Δt 2 n0 3 nr2 4 nr4 5 nz1 6 nz2 7 NZ3 8 nz4 9 tanα 10 tanβ

[0061] Table 1

[0062] The surface shape definition for Gradient5 in Zemax design software can be referenced using the following formula:

[0063]

[0064] Where x and y are the horizontal and vertical coordinates, respectively, c is the curvature (the reciprocal of the radius), r is the radial coordinate in lens units, k is the conic constant, and tanα and tanβ are the tangents to the tilt angles of x and y.

[0065] The gradient profile of the Gradient 5 surface can be referenced by the following formula:

[0066] n ref =n0+n r2 r 2 +n r4 r 4 +n z1 z+n z2 z 2 +n z3 z 3 +n z4 z 4

[0067] Where, r 2 =x 2 +y 2 .

[0068] Through simulation verification, in order to ensure that the self-focusing lens 210 has the same optical performance as a microlens with a diameter of 0.5 mm and a focal length of 3.8 mm, such as focusing, resolution, and contrast, the parameters of the self-focusing lens 210 can be set according to the parameter setting method in Table 2. The specific optical performance simulation results of the self-focusing lens 210 can be referenced. Figure 5 :

[0069] Parameter# Definition Design 1 Δt 0.523 2 n0 1.629 3 nr2 -0.148 4 nr4 1.132E-03 5 nz1 0 6 nz2 0 7 NZ3 0 8 nz4 0 9 tanα 0 10 tanβ 0

[0070] Table 2

[0071] To ensure that the self-focusing lens 210 possesses the same focusing, resolution, and contrast optical performance as a microlens with a diameter of 0.4 mm and a focal length of 3 mm, the parameters of the self-focusing lens 210 can be set according to the parameter setting method in Table 3. A schematic diagram of the optical performance simulation results of the self-focusing lens 210 can be referenced. Figure 6 :

[0072]

[0073]

[0074] Table 3

[0075] Therefore, in the process of manufacturing VR optical modules, multiple self-focusing lenses 210 can be used to form a lens array 200, and the distance between the lens array 200 and the display screen 100 can be set at 3.2mm. The distance from the eyeball (observation point) to the lens array 200 can be set at 22mm. A curved screen with a central angle of 180 degrees corresponding to the arc can be used as the display screen to achieve an ultra-thin VR optical module with a field of view greater than or equal to 170°. This allows the VR optical module to take into account both imaging effect and assembly positioning, thereby improving the application prospects of the VR optical module.

[0076] It should be noted that the examples described above in this embodiment are merely illustrative for ease of understanding and do not constitute a limitation on the technical solution of this invention. The step divisions of the various methods described above are only for clarity of description. In implementation, they can be combined into one step or some steps can be split into multiple steps. As long as they include the same logical relationship, they are all within the protection scope of this patent. Adding insignificant modifications or introducing insignificant designs to the algorithm or process, without changing the core design of the algorithm and process, are also within the protection scope of this patent.

[0077] Another embodiment of this application relates to an electronic device, including the VR optical module described above, for displaying VR video content to a user.

[0078] Those skilled in the art will understand that the above embodiments are specific examples of implementing the present invention, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of the present invention.

Claims

1. A VR optical module, characterized by, The VR optical module comprises: a display screen having opposite front and back surfaces and extending along a first direction; the display screen is a curved screen, and an arc formed along the first direction corresponds to a central angle of 110° to 180°; a lens array is arranged opposite the front surface of the display screen, and the lens array comprises a plurality of self-focusing lenses arranged along the first direction, and at least two microlenses respectively located at different side edges of the array; an angle formed by any two microlenses located at different sides and a line connecting the two microlenses and a viewing point of the VR optical module is 110° to 180°.

2. The VR optical module of claim 1, wherein, In a direction perpendicular to the front surface of the display screen, a distance between the back surface of the display screen and a side of the lens array away from the display screen is 0 mm to 10 mm.

3. The VR optical module of claim 1, wherein, Each self-focusing lens of the plurality of self-focusing lenses is circular, elliptical or polygonal in a cross section perpendicular to the extending direction.

4. The VR optical module of claim 1, wherein, A central refractive index of each self-focusing lens of the plurality of self-focusing lenses is 1.5 to 2.

0.

5. The VR optical module of claim 4, wherein, A maximum step of the self-focusing lens is 0 to 99.

6. The VR optical module of claim 4, wherein, A focal length of the self-focusing lens is 2 mm to 25 mm.

7. An electronic device, comprising: The VR optical module comprises any one of claims 1 to 6.

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