Optical system and VR device

Abstract

The utility model discloses an optical system and VR equipment. The optical system comprises a lens group, a composite film group, a light splitting element and a display module. The lens group comprises a first lens, a second lens and a third lens which are sequentially arranged in the first direction, the first lens is a plano-convex lens, the second lens is a biconcave lens, and the third lens is a biconvex lens; the surface, away from the second lens, of the first lens is a convex surface, the composite film group is arranged on the surface, close to the second lens, of the first lens, and the composite film group comprises an absorption type polarizing film, a reflection type polarizing film and a quarter-wave plate which are sequentially arranged in the first direction; the light splitting element is arranged on the side, away from the second lens, of the third lens, the display module is arranged on the side, away from the second lens, of the third lens, and a circular polarizer is arranged on the side, facing the third lens, of the display module. Compared with the prior art, the size and the weight of the VR equipment are reduced, the imaging quality is improved, and the use experience of different crowds is considered.

Description

TECHNICAL FIELD

[0001] The utility model relates to optical technology field, especially relate to an optical system and VR device. BACKGROUND

[0002] In the VR device, the optical system is the core component of the VR device. The VR device can realize the function of magnifying image display in a short distance based on the optical system, and further bring the user immersive visual experience. With the user's requirement for the VR device being higher and higher, the volume and weight of the existing VR device cannot well meet the user's demand.

[0003] In the prior art, the optical system in the VR device usually adopts Pancake structure to reduce the volume and weight of the VR device, and different Pancake structure designs will also affect the volume, weight and imaging quality of the whole VR device. Moreover, the existing VR device cannot well take into account the use experience of myopic population.

[0004] In view of this, it is necessary to provide an optical system and VR device to solve the above problems. SUMMARY

[0005] In view of the deficiencies in the prior art, the utility model provides an optical system and VR device to reduce the volume and weight of the VR device, improve the imaging quality of the VR device, and improve the use experience of the VR device in response to different user groups.

[0006] To achieve the above purpose, the first aspect of the utility model provides an optical system, which comprises a lens group, a composite film group, a light splitting element and a display module; the lens group comprises a first lens, a second lens and a third lens arranged in sequence along a first direction, the first lens is a plano-convex lens, the second lens is a double-concave lens, and the third lens is a double-convex lens; one side of the first lens away from the second lens is a convex surface, the composite film group is arranged on one side of the first lens close to the second lens, and the composite film group comprises an absorbing polarizing film, a reflecting polarizing film and a quarter-wave plate arranged in sequence along the first direction; the light splitting element is arranged on one side of the third lens away from the second lens, the display module is arranged on one side of the third lens away from the second lens, and a circular polarizer is arranged on one side of the display module facing the third lens.

[0007] In a preferred embodiment, the central thickness of the first lens ranges from 2mm to 4mm, the refractive index of the first lens ranges from 1.45 to 1.55, and the curvature radius of the convex surface of the first lens ranges from 250mm to 280mm.

[0008] In a preferred embodiment, the center thickness of the second lens ranges from 3.6 mm to 3.8 mm, the refractive index of the second lens ranges from 1.65 to 1.7, the radius of curvature of the side of the second lens close to the first lens is from -2000 mm to -3200 mm, and the radius of curvature of the side of the second lens away from the first lens is from 190 mm to 195 mm.

[0009] In a preferred embodiment, the center thickness of the third lens is less than or equal to 10 mm, the refractive index of the third lens ranges from 1.45 to 1.55, the radius of curvature of a surface of the third lens close to the second lens is 80 mm to 90 mm, and the radius of curvature of a surface of the third lens away from the second lens is -140 mm to -145 mm.

[0010] In a preferred embodiment, the center distance between the second lens and the first lens ranges from 1 mm to 1.5 mm.

[0011] In a preferred embodiment, the center distance between the second lens and the third lens ranges from 0.4 mm to 1 mm.

[0012] In a preferred embodiment, the second lens can be adjusted toward or away from the first lens, and the third lens can be adjusted toward or away from the display module.

[0013] In a preferred embodiment, the convex surface of the first lens is aspherical.

[0014] In a preferred embodiment, the aspheric surface of the convex surface of the first lens has an order of 12 or 14.

[0015] A second aspect of the present invention provides a VR device comprising any one of the above optical systems.

[0016] The beneficial effects of the present invention are as follows: it is based on the principle of the Pancake structure, adopts a three-piece structural design, and arranges a plano-convex lens, a biconcave lens and a biconvex lens in sequence along the first direction, and then combines the use of a composite film group and a spectroscopic element, which can reduce the volume and weight of the optical system, thereby reducing the volume and weight of the VR device, improving the imaging quality, and taking into account the user experience of different groups of people. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic structural diagram of the optical system provided in an embodiment of the present utility model.

[0018] Figure 2 This is a schematic structural diagram of the composite module provided in an embodiment of the present utility model. DETAILED DESCRIPTION

[0019] In the utility model, the terms "arrange", "have" and "connect" should be understood in a broad sense. For example, it can be fixed connection, detachable connection, or integral structure; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or internal communication between two devices, elements or components. For those skilled in the art, the specific meaning of the above terms in the utility model can be understood according to the specific circumstances.

[0020] The terms "first" and "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined as "first" and "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "multiple" is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0021] In addition, in addition to being used to indicate the orientation or positional relationship, the above-mentioned part of the term can also be used to indicate other meanings, for example, the term "upper" can also be used to indicate a certain dependent relationship or connection relationship in some cases. For those skilled in the art, the specific meaning of these terms in the utility model can be understood according to the specific circumstances.

[0022] In order to make the purpose, technical scheme and advantages of the utility model more clear and understandable, the utility model is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the utility model, and are not used to limit the utility model.

[0023] In order to make the purpose, technical scheme and advantages of the utility model more clear and understandable, the utility model is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the utility model, and are not used to limit the utility model.

[0024] Specifically, the following is the content of the first aspect of the utility model:

[0025] Please refer to Figure 1 With Figure 2 In the embodiment, an optical system 100 includes a lens group, a composite film group 2, a light splitting element 3 and a display module 4.

[0026] The lens group includes a first lens 11, a second lens 12 and a third lens 13 arranged in sequence along a first direction, the first lens 11 is a plano-convex lens, the second lens 12 is a biconcave lens, and the third lens 13 is a biconvex lens; the side of the first lens 11 away from the second lens 12 is a convex surface, the composite film group 2 is arranged on the side of the first lens 11 close to the second lens 12, and the composite film group 2 includes an absorptive polarizing film 21, a reflective polarizing film 22 and a quarter-wave plate 23 arranged in sequence along the first direction; the spectrometer 3 is arranged on the side of the third lens 13 away from the second lens 12, the display module 4 is arranged on the side of the third lens 13 away from the second lens 12, and a circular polarizer 5 is provided on the side of the display module 4 facing the third lens 13.

[0027] The reflective polarizing film 22 is used to reflect S-polarized light and transmit P-polarized light; the linear polarization direction of the absorptive polarizing film 21 is S-polarized light; and the quarter-wave plate 23 can convert linearly polarized light into circularly polarized light or elliptically polarized light, or vice versa. The spectroscopic element 3 is a semi-transparent, semi-reflective film. The display module 4 can be an LCD display, an OLED display, a Micro OLED display, a Mini LED display, etc., without limitation. It is easy to understand that the optical system 100 provided in this embodiment adopts a three-piece optical path structure design, which can, to a certain extent, balance the imaging quality of the optical system 100 with the volume and weight of the optical system 100.

[0028] Specifically, the optical path principle of the optical system 100 provided in this embodiment is as follows: Assuming that the light emitted by the display module 4 is linearly polarized light, after the light emitted by the display module 4 passes through the circular polarizer 5, the linearly polarized light becomes left-handed circularly polarized light. After the light reaches the upper beam splitter 3 of the third lens 13 (that is, after the light reaches the semi-transparent and semi-reflective film on the third lens 13), part of the light is transmitted into the lens group. After passing through the third lens 13 and the second lens 12, before reaching the quarter-wave plate 23, the light is still left-handed circularly polarized light. After the light passes through the quarter-wave plate 23, the left-handed circularly polarized light is converted into vertical linear polarized light. Then, the light reaches the reflective polarizer 22 on the first lens 11 for the first time. The reflective polarizer 22 can only transmit P linearly polarized light. However, the polarization direction of the light is perpendicular to that of the reflective polarizing film, so it cannot be transmitted. Instead, the vertically polarized light is reflected toward the display module 4 while maintaining its polarization state. After the light passes through the quarter-wave plate 23 again, the vertically polarized light is converted into left-handed circularly polarized light. It passes through the second lens 12 and the third lens 13 again. After reaching the beam splitter 3, it is reflected toward the second lens 12 again, and its polarization state is converted into right-handed circularly polarized light. After passing through the third lens 13, the second lens 12, and the quarter-wave plate 23 again, the light is converted into horizontally polarized light. After passing through the reflective polarizing film 22, the absorptive polarizing film 21 absorbs a small amount of S-polarized light in the light. Then, the light passes through the first lens 11 and enters the pupil 6.

[0029] It can be understood that the optical system 100 provided in this embodiment is based on the principle of the Pancake structure and adopts a three-piece optical path structure design. A plano-convex lens, a biconcave lens and a biconvex lens are arranged in sequence along the first direction. Combined with the composite film group 2 and the spectroscopic element 3, it can achieve the reduction of the volume and weight of the VR device and improve the imaging quality of VR.

[0030] In order for the optical system 100 to better meet usage requirements and correct field curvature and distortion to improve imaging quality and resolution, certain requirements are placed on the parameters of the lens group in the optical system 100.

[0031] Furthermore, in one embodiment, the center thickness of the first lens 11 ranges from 2 mm to 4 mm, the refractive index of the first lens 11 ranges from 1.45 to 1.55, and the radius of curvature of the convex surface of the first lens 11 ranges from 250 mm to 280 mm. Preferably, the center thickness of the first lens 11 is 3 mm, the refractive index of the first lens 11 is 1.50, and the radius of curvature of the convex surface of the first lens 11 is 265 mm.

[0032] Furthermore, in one embodiment, the center thickness of the second lens 12 ranges from 3.6 mm to 3.8 mm, the second lens 12 is made of a high-refractive-index material, the refractive index of the second lens 12 ranges from 1.65 to 1.7, the radius of curvature of the side of the second lens 12 close to the first lens 11 ranges from -2000 mm to -3200 mm, and the radius of curvature of the side of the second lens 12 away from the first lens 11 ranges from 190 mm to 195 mm.

[0033] Preferably, the center thickness of the second lens 12 is 3.7 mm, the refractive index of the second lens 12 is 1.65, the curvature radius of the side of the second lens 12 close to the first lens 11 is -2600 mm, and the curvature radius of the side of the second lens 12 away from the first lens 11 is 193 mm.

[0034] It is understandable that the second lens 12 has a higher refractive index, which can better offset the optical path difference between the first lens 11 and the third lens 13 , thereby better eliminating chromatic aberration of the optical system 100 .

[0035] Furthermore, in one embodiment, the center thickness of the third lens 13 is less than or equal to 10 mm, the refractive index of the third lens 13 ranges from 1.45 to 1.55, the radius of curvature of a surface of the third lens 13 close to the second lens 12 is 80 mm to 90 mm, and the radius of curvature of a surface of the third lens 13 away from the second lens 12 is -140 mm to -145 mm.

[0036] Preferably, the center thickness of the third lens 13 is 8 mm, the refractive index of the third lens 13 is 1.50 (that is, the refractive index of the third lens 13 is the same as the refractive index of the first lens 11), the curvature radius of the side of the third lens 13 close to the second lens 12 is 85 mm, and the curvature radius of the side of the third lens 13 away from the second lens 12 is -143 mm.

[0037] As will be appreciated, third lens 13 utilizes a biconvex lens with a larger aperture, which increases the folding distance of the optical path, thereby reducing the size of optical system 100 and increasing its field of view. The refractive index of third lens 13 is the same as that of first lens 11, eliminating the need for reselected materials during processing, effectively reducing related process steps and improving production efficiency.

[0038] Furthermore, in one embodiment, the center distance between the second lens 12 and the first lens 11 ranges from 1 mm to 1.5 mm; the center distance between the second lens 12 and the third lens 13 ranges from 0.4 mm to 1 mm.

[0039] It can be understood that, due to the existence of the composite film group 2 between the first lens 11 and the second lens 12, it is necessary to ensure that the center distance range between the second lens 12 and the first lens 11 is 1 mm to 1.5 mm. Since the second lens 12 and the third lens 13 are both aspheric surfaces, and in order to make the overall volume of the optical system 100 smaller, it is necessary to ensure that the center distance range between the second lens 12 and the third lens 13 is between 0.4 mm and 1 mm, so as to avoid overlapping between the second lens 12 and the third lens 13.

[0040] Furthermore, the existing VR device generally does not have a diopter adjustment function or has a small diopter adjustment range. In order to meet the use requirements of users with different vision conditions and improve the use experience of different user groups, a larger diopter adjustable range is needed based on the size and weight of the VR device.

[0041] In one embodiment, the second lens 12 can be adjusted towards or away from the first lens 11, and the third lens 13 can be adjusted towards or away from the display module 4.

[0042] By changing the distance between the first lens 11 and the second lens 12, and the distance between the third lens 13 and the display module 4, a large range of diopter adjustment from -7D to 0D can be achieved. It can be understood that, by changing the gap between the first lens 11 and the second lens 12, and the gap between the third lens 13 and the display module 4, the time required for light beam folding and convergence is essentially changed, thereby achieving the function of large range of diopter adjustment of the optical system 100.

[0043] Specifically, when the second lens 12 is adjusted towards the first lens 11, the light passing area of the one side of the first lens 11 towards the second lens 12 is reduced, and the light passing area of the one side of the second lens 12 towards the third lens 13 is increased, so that the light emitted by the first lens 11 is folded and converged in advance, the optical path difference of the second lens 12 and the third lens 13 is changed, thereby changing the light convergence effect of the near-eye display, and adjusting the diopter. Similarly, when the third lens 13 is adjusted towards the display module 4, the light passing area of the one side of the third lens 13 towards the display module 4 is reduced, so that the light incident by the third lens 13 is transmitted early, and the optical path of the light folded by the third lens 13 is prolonged, thereby changing the light convergence effect of the near-eye display.

[0044] It is easy to understand that by adjusting the second lens 12 and the third lens 13 respectively to change the refractive power of the lens group, the function of a large range of refractive power adjustment of the optical system 100-7D to 0D can be realized, thereby meeting the use requirements of users with different vision conditions and improving the use experience of different user groups.

[0045] Further, to improve the imaging quality of the optical system 100 at different refractive powers, more aspheric surfaces can be used to improve the imaging quality of the optical path at different refractive powers. In an embodiment, the convex surface of the first lens 11 is an aspheric surface.

[0046] Specifically, the order of the aspheric surface of the first lens 11, the second lens 12 and the third lens 13 is adjusted from 10 orders to 12 orders or 14 orders, and then based on the calculation formula of the refractive power, the virtual image distance at 0D-7D refractive power is calculated, which is ∞, -1000mm, -500, -333.33mm, -250mm, -200mm, -166.667mm and 142.85mm, respectively. Then, based on the adjustment of the distance between the second lens 12 and the first lens 11 and the distance between the third lens 13 and the display module 4, the focusing is realized.

[0047] In a preferred embodiment, the aspheric surface of the first lens 11, the second lens 12 and the third lens 13 is a Q-type aspheric surface. It is easy to understand that on the basis of ensuring the imaging quality of the optical system 100, the Q-type aspheric surface has the characteristics of high optimization design efficiency, high processing and detection convenience.

[0048] In summary, the optical system 100 provided by the utility model is based on the principle of Pancake structure, adopts a three-piece structure design, sequentially arranges a plano-convex lens, a double-concave lens and a double-convex lens along the first direction, and combines the use of the composite film group 2 and the light splitting element 3, so that the volume and weight of the optical system 100 can be reduced, thereby reducing the volume and weight of the VR device and improving the imaging quality. By adjusting the second lens 12 and the third lens 13, a large refractive power range can be adjusted to take into account the use experience of different groups of people.

[0049] The following is the content of the second aspect of the utility model:

[0050] The utility model provides a kind of VR equipment, it includes aforementioned optical system 100.The VR equipment is based on the principle of Pancake structure, adopts three-piece structure design, plano-convex lens, double-concave lens and double-convex lens are sequentially arranged along the first direction, combined with using composite film group 2 and light splitting element 3, the volume and weight of VR equipment can be reduced, and then the volume and weight of VR equipment are reduced, improve imaging quality, further through adjusting second lens 12 and third lens 13, the adjustment of relatively large diopter range can be realized, to give consideration to the use experience of different population.

[0051] The above is only the specific embodiment of the present application, it should be pointed out, for the ordinary skill in the art, without departing from the principle of the present application, can make a number of improvements and refinements, these improvements and refinements also should be regarded as the protection scope of the present application.

Claims

1. An optical system, characterized in that: It includes a lens group, a composite film group, a spectroscopic element and a display module; the lens group includes a first lens, a second lens and a third lens arranged in sequence along a first direction, the first lens is a plano-convex lens, the second lens is a biconcave lens, and the third lens is a biconvex lens; the side of the first lens away from the second lens is a convex surface, the composite film group is arranged on the side of the first lens close to the second lens, the composite film group includes an absorptive polarizing film, a reflective polarizing film and a quarter-wave plate arranged in sequence along the first direction; the spectroscopic element is arranged on the side of the third lens away from the second lens, the display module is arranged on the side of the third lens away from the second lens, and a circular polarizing plate is arranged on the side of the display module facing the third lens.

2. An optical system according to claim 1, characterized in that: The center thickness of the first lens ranges from 2 mm to 4 mm, the refractive index of the first lens ranges from 1.45 to 1.55, and the curvature radius of the convex surface of the first lens ranges from 250 mm to 280 mm.

3. An optical system according to claim 1, characterized in that: The center thickness of the second lens ranges from 3.6 mm to 3.8 mm, the refractive index of the second lens ranges from 1.65 to 1.7, the curvature radius of the second lens close to the first lens is from -2000 mm to -3200 mm, and the curvature radius of the second lens away from the first lens is from 190 mm to 195 mm.

4. An optical system according to claim 1, characterized in that: The center thickness of the third lens is less than or equal to 10 mm, the refractive index of the third lens ranges from 1.45 to 1.55, the curvature radius of the side of the third lens close to the second lens is 80 mm to 90 mm, and the curvature radius of the side of the third lens away from the second lens is -140 mm to -145 mm.

5. An optical system according to claim 1, characterized in that: A center distance between the second lens and the first lens ranges from 1 mm to 1.5 mm.

6. An optical system according to claim 1 or 5, characterized in that: The center distance between the second lens and the third lens ranges from 0.4 mm to 1 mm.

7. An optical system according to claim 1, characterized in that: The second lens can be adjusted toward or away from the first lens, and the third lens can be adjusted toward or away from the display module.

8. An optical system according to claim 7, characterized in that: The convex surface of the first lens is aspherical.

9. An optical system according to claim 8, characterized in that: The aspheric surface of the convex surface of the first lens has an order of 12 or 14.

10. A VR device, characterized in that: An optical system comprising any one of claims 1 to 9.

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