Optical display lens and VR display system

Abstract

The invention provides an optical display lens and a VR display system, which can improve the PPD of a concerned display area through optical design under the condition of not changing the configuration of hardware such as a display chip. The optical display lens is used for being arranged on the display side of a display chip to form a VR display system, and the optical display lens sequentially comprises a diaphragm, a polarization beam splitting element, a quarter-wave plate, a first lens group and a partial reflection and transmission element from the object side to the image side, the actual focal length of the optical display lens is greater than the theoretical focal length of the optical display lens so as to improve the angular resolution of a display area of interest on the VR display system.

Description

Technical Field

[0001] The present invention relates to the field of virtual reality technology, and in particular to an optical display lens and a VR display system. Background Art

[0002] In recent years, near-eye display (NED) technologies such as augmented reality (AR) and virtual reality (VR) have become increasingly mature, especially VR technology has made amazing progress in recent years and has become a popular application in many fields such as science and technology, entertainment, and education. Although the resolution of VR devices has been greatly improved in the past few years, the resolution of VR headsets is still relatively low, and users will experience pixelation (i.e., Screen Door Effect) when viewing the virtual world, which makes it difficult for users to ignore the gaps between pixels, thus affecting the immersive experience.

[0003] In order to improve the quality of VR experience, new technologies and concepts are constantly emerging, such as the key concept of pixel per degree (PPD), which has become a key indicator for measuring and improving the performance of VR devices. The PPD value represents the number of pixels contained within a unit field of view (1°); in simple terms, the higher the VR-PPD value, the higher the resolution of the VR device, the better the image quality, and the clearer and more realistic the user's visual experience in the virtual world. With the continuous development of technology, improving VR-PPD has become an industry consensus.

[0004] As we all know, since the resolution limit of the human eye under normal vision is about 50-60PPD (PPD at the retina level), when the PPD value of the head-mounted display product is low, the human eye may feel the pixel lattice of the head-mounted display product under normal vision, and the smaller the PPD value, the stronger the lattice feeling, which is commonly known as the screen door effect; conversely, the closer the PPD value of the head-mounted display product is to 60, the closer the image clarity of the product is to the resolution limit of the human eye, and the clearer the image appears to the human eye. At present, high-end VR devices on the market are working hard to increase the PPD value so that users can enjoy higher-definition and realistic images in an immersive experience; some devices have successfully increased the VR-PPD value to 30, which has significantly improved the pixelation phenomenon.

[0005] However, the methods used by these devices to improve VR-PPD usually include improving display resolution, optimizing display technology, and increasing refresh rate, but these methods will bring some new challenges while improving PPD. For example, although improving display resolution can present more pixels per unit field of view to improve image quality, high-resolution displays often require higher computing performance, which also means that the hardware requirements of VR systems will increase accordingly, resulting in higher energy consumption and increased equipment costs. Alternatively, using advanced display devices such as OLED or MicroLED to optimize display technology can further increase pixel density and reduce pixel spacing to improve PPD, but advanced display devices will also lead to a significant increase in costs. In addition, increasing the refresh rate can also improve the visual experience, and a high refresh rate helps reduce screen smearing and blurring, making the virtual world smoother and further enhancing immersion, but a high refresh rate display will also lead to higher energy consumption, which greatly increases the cost of equipment. Summary of the invention

[0006] One advantage of the present invention is that it provides an optical display lens and a VR display system, which can improve the PPD of a display area of ​​interest through optical design without changing the hardware configuration of the display chip.

[0007] Another advantage of the present invention is to provide an optical display lens and a VR display system, wherein, in one embodiment of the present invention, the optical display lens can flexibly improve the PPD of the display area of ​​interest by effectively adjusting and controlling the design focal length, thereby improving the user's viewing experience.

[0008] Another advantage of the present invention is to provide an optical display lens and a VR display system, wherein, in one embodiment of the present invention, the optical display lens can achieve the purpose of increasing the PPD of the central main display area to greater than 30 by targeted adjustment of the optical design and specific architecture.

[0009] Another advantage of the present invention is to provide an optical display lens and a VR display system, wherein, in one embodiment of the present invention, the optical display lens can maximize the PPD of the central display area while taking into account the PPD of the edge display area, thereby achieving effective adjustment of the PPD of the displayed image.

[0010] Another advantage of the present invention is to provide an optical display lens and a VR display system, wherein in order to achieve the above-mentioned purpose, no expensive materials or complex structures are required in the present invention. Therefore, the present invention successfully and effectively provides a solution, not only providing a simple optical display lens and a VR display system, but also increasing the practicality and reliability of the optical display lens and the VR display system.

[0011] In order to achieve at least one of the above advantages or other advantages and purposes of the present invention, the present invention provides an optical display lens, which is used to be arranged on the display side of a display chip to form a VR display system. The optical display lens includes, from the object side to the image side, an aperture, a polarization beam splitter, a quarter-wave plate, a first lens group, and a partial reflective element; the actual focal length of the optical display lens is greater than the theoretical focal length of the optical display lens, so as to improve the angular resolution of the display area of ​​interest on the VR display system.

[0012] According to one embodiment of the present application, the theoretical focal length of the optical display lens is EFL0=IMH / tanθ0, wherein IMH represents the maximum half image height of the display chip; θ0 represents the maximum half field of view angle of the VR display system.

[0013] According to one embodiment of the present application, the focal length increase ratio of the optical display lens δ=(EFL-EFL0) / EFL*100%, wherein: EFL is the actual focal length of the optical display lens; EFL0 is the theoretical focal length of the optical display lens.

[0014] According to an embodiment of the present application, the focal length increase ratio of the optical display lens is greater than or equal to 30%.

[0015] According to an embodiment of the present application, the focal length increase ratio of the optical display lens is greater than or equal to 30% and less than or equal to 34%.

[0016] According to an embodiment of the present application, the focal length increase ratio of the optical display lens is greater than or equal to 35%.

[0017] According to one embodiment of the present application, the optical display lens further includes a second lens group located on the image side of the partially reflective element and a flat glass located in the light path between the aperture and the polarization splitter element, and the polarization splitter element is a PBS film glued between the flat glass and the quarter wave plate.

[0018] According to one embodiment of the present application, the first lens group includes a first lens, and the partially reflective element is a BS film glued to the image side surface of the first lens.

[0019] According to one embodiment of the present application, the first lens group includes a first lens and a second lens, the first lens is located in the light path between the quarter-wave plate and the second lens, and the partial reflective element is a BS film glued to the image side surface of the second lens.

[0020] According to another aspect of the present application, the present application further provides a VR display system, including:

[0021] Display chip; and

[0022] Any of the above-mentioned optical display lenses is arranged on the display side of the display chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a structural schematic diagram of a VR display system according to an embodiment of the present application;

[0024] Figure 2 A first example of a VR display system according to the above-mentioned embodiment of the present application is shown;

[0025] Figure 3 A second example of the VR display system according to the above embodiment of the present application is shown;

[0026] Figure 4 is a schematic diagram of the optical path of the foldback display solution according to Comparative Example 1 of the present application;

[0027] Figure 5A and Figure 5B Schematic diagrams of field curvature and distortion of the foldback display solution according to comparative example 1 of the present application are respectively shown;

[0028] Figure 6 is a schematic diagram of an optical path of a VR display system according to Example 1 of the present application;

[0029] Fig. 7A and Figure 7B Schematic diagrams of field curvature and distortion of a VR display system according to Embodiment 1 of the present application are respectively shown;

[0030] Figure 8 is a schematic diagram of an optical path of a VR display system according to Example 2 of the present application;

[0031] Fig. 9A and Fig. 9B Schematic diagrams of field curvature and distortion of a VR display system according to Embodiment 2 of the present application are respectively shown;

[0032] Fig.10 is a schematic diagram of an optical path of a VR display system according to Example 3 of the present application;

[0033] Fig.11A and Fig. 11B A schematic diagram of field curvature and a schematic diagram of distortion of a VR display system according to Example 3 of the present application are respectively shown.

[0034] Explanation of the main component symbols: 1. VR display system; 10. Display chip; 11. Liquid crystal display; 20. Optical display lens; 21. Aperture; 22. Polarization splitter element; 220. PBS film; 23. Quarter wave plate; 24. First lens group; 241. First lens; 242. Second lens; 25. Partial reflective element; 250. BS film; 26. Second lens group; 27. Flat glass.

[0035] The above description of the main component symbols is combined with the accompanying drawings and specific implementation methods to further illustrate the present application in detail. DETAILED DESCRIPTION

[0036] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art can think of other obvious variations. The basic principles of the present invention defined in the following description can be applied to other embodiments, variations, improvements, equivalents, and other technical solutions that do not deviate from the spirit and scope of the present invention.

[0037] Those skilled in the art should understand that, in the disclosure of the present invention, the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0038] In the present invention, the term "one" in the claims and the specification should be understood as "one or more", that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple. Unless it is clearly indicated in the disclosure of the present invention that the number of the element is only one, the term "one" cannot be understood as unique or single, and the term "one" cannot be understood as a limitation on the quantity.

[0039] In the description of the present invention, it should be understood that "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through a medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0041] Considering that the existing methods for improving VR-PPD can improve PPD to a certain extent, they are all achieved by increasing hardware requirements, which not only leads to higher energy consumption, but also greatly increases the cost of equipment. Therefore, the present application creatively proposes an optical display lens and a VR display system, which can improve the PPD of the display area of ​​interest through optical design without changing the hardware configuration such as the display chip.

[0042] Specifically, refer to the accompanying drawings of the specification of this application. Figure 1 According to one embodiment of the present application, a VR display system 1 is provided, which may include a display chip 10 and an optical display lens 20 arranged on the display side of the display chip 10, so that the image light emitted from the display chip 10 is first modulated by the optical display lens 20 and then emitted into the human eye to form an image, that is, the user watches the picture displayed by the display chip 10 through the optical display lens 20 to obtain a virtual reality experience.

[0043] More specifically, if Figure 1As shown, the optical display lens 20 includes, from the object side to the image side, an aperture 21, a polarization beam splitter 22, a quarter wave plate 23, a first lens group 24, and a partial reflective element 25; the actual focal length of the optical display lens 20 is greater than the theoretical focal length of the optical display lens 20, so as to improve the angular resolution of the display area of ​​interest on the VR display system 1. In this way, the image light emitted by the display chip 10 will first partially pass through the partial anti-transmission element 25, and then pass through the first lens group 24; then, this part of the image light will form a first polarized image light after passing through the quarter wave plate 23 to be reflected by the polarization beam splitter 22; then, the reflected first polarized image light will successively pass through the quarter wave plate 23 and the first lens group 24 to be partially reflected by the partial anti-transmission element 25; finally, this part of the reflected image light will pass through the first lens group 24 and the quarter wave plate 23 again to form a second polarized image light to pass through the polarization beam splitter 22 and then pass through the aperture 21 to enter the human eye for imaging, and the optical path is folded to reduce the overall thickness of the VR display system 1, so as to facilitate head-mounted display. It can be understood that the polarization direction of the first polarized image light mentioned in the present application can be perpendicular to the polarization direction of the second polarized image light, for example, when the first polarized image light is S polarized light, the second polarized image light is P polarized light.

[0044] It is worth noting that the optical display lens 20 mentioned in the present application does not require changes to other hardware such as the display chip 10. From the perspective of design optimization of the optical system, it is only necessary to increase the design focal length (i.e., the actual focal length) of the optical display lens 20 compared to the theoretical focal length, so as to improve the angular resolution of the display area of ​​interest on the VR display system 1; that is, the VR display system 1 mentioned in the present application can achieve a significant improvement in the angular resolution of the optical system only from the perspective of design optimization and adjustment of the optical system without increasing the energy consumption and equipment cost of the equipment.

[0045] In other words, the VR display system 1 mentioned in the present application effectively adjusts and controls the system distortion by adjusting the design focal length of the optical display lens 20, that is, completes the adjustment and control of the distortion of part of the display area, and realizes the PPD improvement of the display area of ​​interest. For example, the present application can reduce the absolute distortion (i.e., the absolute value of the distortion) of the central display area (such as within 50% of the field of view) by increasing the design focal length of the optical display lens 20 to be greater than the theoretical focal length of the optical display lens 20, and at the same time increase the absolute distortion of the edge field of view (such as outside 50% of the field of view), so as to maximize the PPD of the central display area while taking into account the PPD of the edge display area, so as to realize the effective adjustment of the PPD of the image displayed by the VR display system 1. It can be understood that the display area of ​​interest on the VR display system 1 mentioned in the present application can refer to the central display area within the field of view of the VR display system 1.

[0046] Optionally, the optical display lens 20 may further include a second lens group 26 located on the image side of the partial reflective element 25; that is, the second lens group 26 is located in the light path between the partial reflective element 25 and the display chip 10, so that the image light emitted by the display chip 10 will first pass through the second lens group 26, and then partially pass through the partial reflective element 25 to pass through the first lens group 24.

[0047] Optionally, the theoretical focal length EFL0 of the optical display lens 20 is equal to IMH / tanθ0, wherein IMH represents the maximum half image height of the display chip 10 ; θ0 represents the maximum half field of view angle of the VR display system 1 .

[0048] Exemplarily: the parameters of the VR display system 1 are as follows: PPD is angular resolution; △PPD is local angular resolution; pixel is pixel size; y is ideal image height; y' is actual image height; θ is field of view angle; IMH is the maximum half image height of the display chip 10; θ0 is the corresponding maximum half field of view angle; EFL0 is theoretical focal length; EFL is actual focal length.

[0049] Then in the VR display system 1: distortion DIS=(y'-y) / y*100%; ideal image height y1 with a viewing angle of θ1=EFL*tanθ1; ideal image height y2 with a viewing angle of θ2=EFL*tanθ2.

[0050] Furthermore, the actual image height y1′ when the viewing angle is θ1 is equal to y1*DIS+y1; the actual image height y2′ when the viewing angle is θ2 is equal to y2*DIS+y2.

[0051] It can be concluded that: the actual image height difference between the field angle θ1 and the field angle θ2 is Δy'=y1'-y2'=(y1-y2)*(DIS+1); the difference between the field angle θ1 and the field angle θ2 is Δθ=θ1-θ2.

[0052] Finally, the local angular resolution ΔPPD of the VR display system 1 is expressed as follows (2):

[0053]

[0054] The angular resolution PPD of the VR display system 1 at a viewing angle of θ1 is expressed by the following formula (3):

[0055]

[0056] In summary, according to the above formula, when the field of view angle is constant, increasing the system focal length can effectively increase the PPD. Therefore, the VR display system 1 mentioned in the present application can effectively control the distortion by increasing the design focal length of the optical display lens 20, so that the angular resolution PPD and the local angular resolution ΔPPD of the central display area of ​​the VR display system 1 can be improved.

[0057] According to the above embodiment of the present application, the focal length increase ratio δ of the optical display lens 20 is (EFL-EFL0) / EFL*100%, wherein: EFL is the actual focal length of the optical display lens 20; EFL0 is the theoretical focal length of the optical display lens 20.

[0058] Exemplarily, the focal length increase ratio δ of the optical display lens 20 can be greater than or equal to 30%, that is, δ = (EFL-EFL0) / EFL*100%≥30%, so as to greatly improve the angular resolution PPD and the local angular resolution △PPD of the central display area of ​​the VR display system 1.

[0059] It is worth noting that the degree of improvement of the design focal length of the optical display lens 20 of the present application varies according to different improvement requirements. For example, if the goal is to maximize the improvement of the angular resolution PPD of the central display area and the local angular resolution △PPD in the central display area, while allowing the local angular resolution △PPD of the edge display area to be sacrificed to a certain extent; in this case, the focal length increase ratio δ of the optical display lens 20 can be greater than or equal to 30% and less than or equal to 34%, that is, 30%≤δ≤34%.

[0060] However, if the angular resolution PPD of the central display area is maximized while the local angular resolution ΔPPD of the edge display area is improved, the focal length increase ratio δ of the optical display lens 20 may be greater than or equal to 35%, that is, δ≥35%.

[0061] It is worth noting that according to the above embodiments of the present application, Figures 1 to 3 As shown, the optical display lens 20 may further include a flat glass 27 located in the optical path between the aperture 21 and the polarization beam splitter 22, and the polarization beam splitter 22 may be implemented as, but not limited to, a PBS film 220 glued between the flat glass 27 and the quarter wave plate 23 to protect the PBS film 220. It is understood that the PBS film 220 of the present application may be used to reflect S light and transmit P light.

[0062] Alternatively, if Figures 1 to 3As shown, the partial reflective element 25 can be implemented as, but not limited to, a BS film 250 glued to the image side of the first lens group 24, for reflecting a portion of the light and transmitting another portion of the light. It is worth noting that the display chip 10 in the VR display system 1 can be implemented as a liquid crystal display 11 (Liquid Crystal Display, LCD for short), for emitting circularly polarized image light. In this way, after the circularly polarized image light emitted by the liquid crystal display 11 passes through the second lens group 26, a portion of the circularly polarized image light will first pass through the BS film 250 to pass through the first lens group 24, and then pass through the quarter wave plate 23 to be converted into S light; then, the S light is reflected back to the quarter wave plate 23 by the PBS film 220 to be converted into circularly polarized light, and a portion of the circularly polarized light after passing through the first lens group 24 will be reflected by the BS film 250 to pass through the first lens group 24, and then pass through the quarter wave plate 23 to be converted into P light; finally, the P light will successively pass through the PBS film 220 and the aperture 21 to enter the human eye to form an image.

[0063] For example, in the first example of the present application, Figure 2 As shown, the first lens group 24 and the second lens group 26 are each composed of one lens to form an optical display lens 20 having a two-piece structure. At this time, the first lens group 24 may include a first lens 241, and the BS film 250 is glued to the image side surface of the first lens 241.

[0064] Of course, in the second example of the present application, Figure 3 As shown, the first lens group 24 may be composed of two lenses, and the second lens group 26 may be composed of one lens, so as to form an optical display lens 20 with a three-lens structure. In this case, the first lens group 24 may include a first lens 241 and a second lens 242, wherein the first lens 241 is located in the optical path between the quarter wave plate 23 and the second lens 242, and the BS film 250 is glued to the image side surface of the second lens 242.

[0065] Optionally, in the second example of the present application, as Figure 3 As shown, the object side of the first lens 241 is glued to the quarter wave plate 23 so as to better protect the PBS film 220 and the quarter wave plate 23 while reducing the overall thickness of the system.

[0066] It can be understood that in other examples of the present application, the first lens group 24 can be composed of three or more lenses; the second lens group 26 can be composed of two or more lenses, which will not be described in detail in the present application.

[0067] It is worth noting that in order to reflect the characteristics and advantages of the VR display system 1 of the present application, the following comparative example 1, embodiment 1, embodiment 2 and simulation test of embodiment 3 are compared and discussed.

[0068] Comparative Example 1: Figure 4 As shown, the reentrant display solution designed based on the conventional design method (VR display solution based on Pancake) has the following specific parameters: display size (Display size) is 46mm; pixel size (PixelSize) is 16.8um; eye box (Eye Box) is 12mm; eye relief (Eye Relief) is 14mm; virtual image distance (VID) is 1.5m; field of view (FOV) is 100°; applicable spectral range is 450nm to 630nm; center field of view MTF>0.7@301p / mm; edge field of view MTF>0.4@301p / mm. After simulation test: the field curvature and distortion of the reentrant display solution according to comparative example 1 are as follows: Figure 5A and Figure 5B As shown, the corresponding actual focal length EFL is 27 mm, and the distortion DIS is -30%. The PPD calculation results of the optical system in the reentrant display solution of Comparative Example 1 are shown in Table 1 below.

[0069] Table 1: Angular resolution calculation table of the foldback display solution of comparative example 1

[0070] FOV(°) Distortion(%) PPD ΔPPD 0.00 0.00％ O 0 2.50 -0.07％ 28.7 28.7 5.00 -0.29％ 28.7 28.7 7.50 -0.65％ 28.6 28.6 10.00 -1.16％ 28.6 28.6 12.50 -1.82％ 28.6 28.5 15.00 -2.63％ 28.6 28.4 17.50 -3.59％ 28.5 28.3 20.00 -4.71％ 28.5 28.2 22.50 -5.97％ 28.4 28.0 25.00 -7.38％ 28.4 27.9 27.50 -8.95％ 28.3 27.7 30.00 -10.67％ 28.2 27.4 32.50 -12.55％ 28.2 27.2 35.00 -14.60％ 28.1 26.9 37.50 -16.81％ 28.0 26.5 40.00 -19.20％ 27.8 26.1 42.50 -21.78％ 27.7 25.5 45.00 -24.54％ 27.5 24.9 47.50 -27.50％ 27.4 24.0 50.00 -30.66％ 27.1 23.1

[0071] It can be seen from Table 1 above that the PPD of the reentrant display solution of Comparative Example 1 in the entire display area is less than 30. However, the present application can effectively control the actual image height distribution corresponding to different FOVs of the system by adjusting the optical design and the specific architecture, so as to effectively improve and regulate the PPD of the system, as shown in the following Examples 1 and 2.

[0072] Example 1: Figure 6 As shown, in the VR display system of the present application, the structural parameters of each functional surface are set in sequence along the reverse direction of the display light path: surface type Type, curvature radius Radius, center thickness Thickness, refractive index Nd, Abbe number Abbe and refraction mode Refract Mode, and the value conditions are shown in Table 2 below; at the same time, the aspheric coefficients of some functional surfaces are shown in Table 3 below:

[0073] Table 2: Structural parameters of the VR display system of Example 1

[0074]

[0075]

[0076] It can be understood that, in the above table, Sphere refers to a spherical surface; Asphere refers to an aspherical surface; Infinity refers to an infinite radius of curvature, that is, the functional surface is a plane.

[0077] Table 3: Aspheric coefficients of the VR display system in Example 1

[0078]

[0079]

[0080] After simulation test: the field curvature and distortion of the VR display system according to the embodiment 1 are as follows: Fig. 7A and Figure 7B As shown, the corresponding actual focal length EFL is 28.2 mm, and the distortion DIS is -32%. The PPD calculation results of the VR display system of Example 1 are shown in Table 4 below.

[0081] Table 4: Angular resolution calculation table of the VR display system of Example 1

[0082] FOV(°) Distortion(%) PPD ΔPPD 0.00 0.00％ 0 O 2.50 0.03％ 29.5 29.5 5.00 0.13％ 29.5 29.6 7.50 0.30％ 29.7 30.0 10.00 0.54％ 29.9 30.5 12.50 0.84％ 30.1 31.2 15.00 1.15％ 30.5 32.0 17.50 1.39％ 30.8 32.8 20.00 1.46％ 31.1 33.5 22.50 1.27％ 31.4 33.8 25.00 0.68％ 31.7 33.7 27.50 -043％ 31.8 33.0 30.00 -2.15％ 31.7 31.4 32.50 -4.53％ 31.5 29.2 35.00 -7.53％ 31.2 26.5 37.50 -11.03％ 30.7 23.7 40.00 -14.90％ 30.1 21.2 42.50 -19.00％ 29.4 19.0 45.00 -23.25％ 28.8 17.1 47.50 -27.70％ 28.0 14.5 50.00 -31.92％ 27.4 15.0

[0083] In summary, Figure 7B It can be seen from the distortion curve shown that the distortion in the central display area (such as the area within 25° of the half field of view angle FOV) is a small positive distortion, but the PPD in the central display area can reach up to 31.8, and the local PPD in the central display area can reach up to 33.8; but at this time, the local PPD at the edge of the field of view is only 15. Therefore, the VR display system of Example 1 of the present application can maximize the improvement of the central local PPD while slightly sacrificing the local PPD at the edge.

[0084] Example 2: Figure 8 As shown, in the VR display system of the present application, the structural parameters of each functional surface are set in sequence along the reverse direction of the display light path: surface type Type, curvature radius Radius, center thickness Thickness, refractive index Nd, Abbe number Abbe and refraction mode Refract Mode, and the value conditions are shown in Table 5 below; at the same time, the aspheric coefficients of some functional surfaces are shown in Table 6 below:

[0085] Table 5: Structural parameters of the VR display system of Example 2

[0086]

[0087]

[0088] It can be understood that, in the above table, Sphere refers to a spherical surface; Asphere refers to an aspherical surface; Infinity refers to an infinite radius of curvature, that is, the functional surface is a plane.

[0089] Table 6: Aspheric coefficient table of VR display system in Example 2

[0090]

[0091]

[0092] After simulation test: the field curvature and distortion of the VR display system according to the second embodiment are as follows: Fig. 9A and Fig. 9B As shown, the corresponding actual focal length EFL is 31 mm and the distortion DIS is -37.5%. The PPD calculation results of the VR display system of Example 2 are shown in Table 7 below.

[0093] Table 7: Angular resolution calculation table of the VR display system of Example 2

[0094] FOV(°) Distortion(%) PPD ΔPPD 0.00 0.00％ 0 0 2.50 -0.01％ 31.8 31.8 5.00 -0.05％ 31.9 31.9 7.50 -0.13％ 31.9 32.1 10.00 -0.29％ 32.0 32.3 12.50 -0.57％ 32.1 32.5 15.00 -1.00％ 32.2 32.7 17.50 -1.63％ 32.3 32.7 20.00 -2.50％ 32.3 32.6 22.50 -3.67％ 32.3 32.2 25.00 -5.17％ 32.2 31.4 27.50 -7.08％ 32.0 30.3 30.00 -9.41％ 31.8 28.6 32.50 -12.19％ 31.4 26.5 35.00 -15.36％ 30.8 24.2 37.50 -18.85％ 30.2 21.9 40.00 -22.53％ 29.6 19.9 42.50 -26.27％ 29.0 18.6 45.00 -29.98％ 28.3 17.9 47.50 -33.59％ 27.8 17.9 50.00 -36.91％ 27.4 19.8

[0095] In summary, Fig. 9B It can be seen from the distortion curve shown that the PPD of the central display area can reach up to 32.3, and the local PPD of the central display area can reach up to 32.7; at this time, the local PPD at the edge of the field of view can reach 19.8. Therefore, the VR display system of Example 2 of the present application maximizes the PPD of the central display area while taking into account the local PPD at the edge of the field of view.

[0096] It is worth noting that although the above-mentioned comparative example 1, embodiment 1 and embodiment 2 of the present application are simulated and tested with a two-piece lens structure, the VR display system mentioned in the present application is not limited to a two-piece lens structure, it can also be a three-piece lens structure or other types of structure forms.

[0097] Example 3: Fig.10 As shown, in the VR display system of the present application, the structural parameters of each functional surface are set in sequence along the reverse direction of the display light path: surface type Type, curvature radius Radius, center thickness Thickness, refractive index Nd, Abbe number Abbe and refraction mode Refract Mode, and the value conditions are shown in Table 8 below; at the same time, the aspheric coefficients of some functional surfaces are shown in Table 9 below:

[0098] Table 8: Structural parameters of the VR display system of Example 3

[0099]

[0100]

[0101] It can be understood that, in the above table, Sphere refers to a spherical surface; Asphere refers to an aspherical surface; Infinity refers to an infinite radius of curvature, that is, the functional surface is a plane.

[0102] Table 9: Aspheric coefficients of the VR display system in Example 3

[0103]

[0104]

[0105] After simulation test: the field curvature and distortion of the VR display system according to the third embodiment are as follows: Fig.11A and Fig. 11B As shown, the corresponding actual focal length EFL is 29.4 mm, and the distortion DIS is -34.4%; the PPD calculation results of the VR display system of Example 3 are shown in Table 10 below.

[0106] Table 10: Angular resolution calculation table of the VR display system of Example 3

[0107] FOV(°) Distortion(%) PPD △PPD 0.00 0.00％ 0 0 2.50 0.05％ 30.5 30.5 5.00 0.20％ 30.6 30.7 7.50 0.42％ 30.8 31.1 10.00 0.67％ 31.0 31.7 12.50 0.88％ 31.3 32.3 15.00 0.99％ 31.5 32.8 17.50 0.91％ 31.8 33.2 20.00 0.54％ 32.0 33.4 22.50 -0.20％ 32.1 33.2 25.00 -1.43％ 32.1 32.3 27.50 -3.21％ 32.0 30.9 30.00 -5.60％ 31.8 28.8 32.50 -8.54％ 31.3 26.3 35.00 -11.95％ 30.8 23.7 37.50 -15.68％ 30.2 21.3 40.00 -19.54％ 29.5 19.6 42.50 -23.42％ 28.9 18.6 45.00 -27.24％ 28.3 18.1 47.50 -30.94％ 27.7 18.2 50.00 -34.25％ 27.4 21.0

[0108] In summary, Fig. 11B It can be seen from the distortion curve shown that the PPD of the central display area can reach up to 32.1, and the local PPD of the central display area can reach up to 33.4; at this time, the local PPD at the edge of the field of view can reach 21.0. Therefore, the VR display system of Example 3 of the present application maximizes the PPD of the central display area while taking into account the local PPD at the edge of the field of view.

[0109] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, 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.

[0110] The above embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An optical display lens, used to be arranged on the display side of a display chip to form a VR display system, characterized in that: The optical display lens includes, from the object side to the image side, an aperture, a polarization beam splitter, a quarter wave plate, a first lens group, and a partial reflective element; the actual focal length of the optical display lens is greater than the theoretical focal length of the optical display lens, so as to improve the angular resolution of the display area of ​​interest on the VR display system.

2. The optical display lens according to claim 1, characterized in that: The theoretical focal length of the optical display lens is EFL0=IMH / tanθ0, wherein IMH represents the maximum half image height of the display chip; θ0 represents the maximum half field angle of the VR display system.

3. The optical display lens according to claim 1, characterized in that: The focal length increase ratio of the optical display lens δ=(EFL-EFL0) / EFL*100%, wherein: EFL is the actual focal length of the optical display lens; EFL0 is the theoretical focal length of the optical display lens.

4. The optical display lens according to claim 3, characterized in that: The focal length increase ratio of the optical display lens is greater than or equal to 30%.

5. The optical display lens according to claim 3, characterized in that: The focal length increase ratio of the optical display lens is greater than or equal to 30% and less than or equal to 34%.

6. The optical display lens according to claim 3, characterized in that: The focal length increase ratio of the optical display lens is greater than or equal to 35%.

7. The optical display lens according to any one of claims 1 to 6, characterized in that: The optical display lens further includes a second lens group located on the image side of the partial reflective element and a flat glass located in the light path between the aperture and the polarization beam splitter element. The polarization beam splitter element is a PBS film glued between the flat glass and the quarter wave plate.

8. The optical display lens according to claim 7, characterized in that: The first lens group includes a first lens, and the partial reflective element is a BS film glued to the image side surface of the first lens.

9. The optical display lens according to claim 7, characterized in that: The first lens group includes a first lens and a second lens, the first lens is located in the light path between the quarter wave plate and the second lens, and the partial reflective element is a BS film glued to the image side surface of the second lens.

10. VR display system, characterized in that: include: Display chip; and The optical display lens according to any one of claims 1 to 9, wherein the optical display lens is disposed on a display side of the display chip.

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