Head-mounted display optical system and VR device

Abstract

The invention discloses a head-mounted display optical system and VR equipment. The head-mounted display optical system comprises a receiving end, a first lens, a second lens, a third lens, a fourth lens and a display, the first lens, the second lens, the third lens and the fourth lens are sequentially arranged between the receiving end and the display along the direction from the receiving end to the display; the first lens and the fourth lens are meniscus lenses which are convex towards the display and have positive focal power, the second lens is a biconvex lens with positive focal power, the third lens is a biconcave lens with negative focal power, and one surface, close to the display, of the fourth lens is an even-order aspheric surface. Compared with the prior art, through the arrangement of the lens group, the compact structure of the optical system is ensured, more light rays can be introduced, a large field angle can be obtained, aberration can be effectively corrected, distortion can be reduced, the imaging quality can be improved, the weight and the size of the VR can be reduced, and the use experience of a user can be improved.

Description

Technical Field

[0001] The present invention relates to the field of optical technology, and in particular to a head-mounted display optical system and VR equipment. Background Art

[0002] With the development of optical technology, users have higher and higher requirements for VR devices. In the design process of existing VR devices, it is necessary to improve the field of view while maintaining high resolution. However, increasing the field of view will bring aberrations to the head-mounted display optical system and increase the distortion of the head-mounted display optical system. In the existing technology, the imaging quality problem is usually solved by increasing the number of lenses, but increasing the number of lenses will increase the complexity of the head-mounted display optical system, increase the volume and weight of the head-mounted display optical system, and thus affect the wearing experience of the VR device.

[0003] In view of this, it is necessary to provide a head-mounted display optical system and a VR device to solve the above-mentioned problems. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a head-mounted display optical system and a VR device, which can reduce the weight and volume of the optical system while improving the imaging quality of the optical system, so as to improve the user experience.

[0005] To achieve the above-mentioned purpose, a first aspect of the present invention provides a head-mounted display optical system, which includes a receiving end, a first lens, a second lens, a third lens, a fourth lens and a display; the first lens, the second lens, the third lens and the fourth lens are sequentially arranged between the receiving end and the display along the direction from the receiving end to the display; the first lens and the fourth lens are both meniscus lenses convex toward the display and have positive optical power, the second lens is a double convex lens with positive optical power, the third lens is a double concave lens with negative optical power, and the surface of the fourth lens close to the display is an even-order aspheric surface.

[0006] In a preferred embodiment, the effective focal lengths of the first lens, the second lens, the third lens and the fourth lens are F1, F2, F3 and F4 respectively, and F1, F2 and F4 are all positive values, and F3 is a negative value.

[0007] In a preferred embodiment, the effective focal length of the head mounted display optical system is F, and satisfies: 1.47≤F1 / F≤1.83, 1.53≤F2 / F≤1.75, -1.71≤F3 / F≤-1.383, 0.23≤F4 / F≤0.27.

[0008] In a preferred embodiment, the refractive indices of the first lens, the second lens, the third lens and the fourth lens at the D line are N1, N2, N3 and N4 respectively, and satisfy: 1.78≤N1≤1.82, 1.78≤N2≤1.86, 1.75≤N3≤1.85, 1.62≤N4≤1.89.

[0009] In a preferred embodiment, the Abbe numbers of the first lens, the second lens, the third lens and the fourth lens at the D line are V1, V2, V3 and V4 respectively, and satisfy: 35≤V1≤70, 35≤V2≤65, 20≤V3≤28, 18≤V4≤50.

[0010] In a preferred embodiment, the half field of view angle of the head mounted display optical system is HFOV, and satisfies: 59°≤HFOV≤60°.

[0011] In a preferred embodiment, the radius of curvature of a side of the first lens close to the receiving end is R1, and the radius of curvature of a side away from the receiving end is R2; the radius of curvature of a side of the second lens close to the receiving end is R3, and the radius of curvature of a side away from the receiving end is R4; the radius of curvature of a side of the third lens close to the receiving end is R5, and the radius of curvature of a side away from the receiving end is R6; the radius of curvature of a side of the fourth lens close to the receiving end is R7, and the following conditions are satisfied: -62.5mm≤R1≤-51.7mm, -32.5mm≤R2≤-29mm, 78mm≤R3≤95mm, -143.32mm≤R4≤-115.8mm, -118.4mm≤R5≤-88mm, 95.27mm≤R6≤135.4mm, -55mm≤R7≤-37.6mm.

[0012] In a preferred embodiment, the even-order aspheric surface of the fourth lens is a 10th-order aspheric surface.

[0013] In a preferred embodiment, the first lens, the second lens, the third lens and the fourth lens are all glass lenses.

[0014] A second aspect of the present invention provides a VR device, which includes the head-mounted display optical system in any of the aforementioned embodiments.

[0015] The beneficial effects of the present invention are as follows: by setting the first lens, the second lens, the third lens and the fourth lens, the light trend of the head-mounted display optical system can be smoothed, more light can be introduced to increase the field of view, and the aberration of the system can be effectively corrected, the distortion can be reduced, and the imaging quality can be improved. At the same time, by setting the shape of the lens group, the weight and volume of the head-mounted display optical system can be effectively reduced, the compactness of the optical system can be improved, and the user experience of the VR device can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of the structure of a head mounted display optical system provided by an embodiment of the present invention;

[0017] Figure 2 A spot diagram of a head mounted display optical system provided by an embodiment of the present invention;

[0018] Figure 3 A field curvature distortion curve diagram of a head mounted display optical system provided by an embodiment of the present invention;

[0019] Figure 4 A transfer function curve diagram of a head mounted display optical system provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0020] In the present invention, the terms "disposed", "provided with" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements or components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0021] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "plurality" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0022] In addition, some of the above terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in some cases. For those skilled in the art, the specific meanings of these terms in the present invention can be understood according to specific circumstances.

[0023] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0024] Specifically, the following is the content provided by the first aspect of the present invention:

[0025] Please refer to Figure 1 In this embodiment, the head mounted display optical system includes a receiving end 1, a first lens 2, a second lens 3, a third lens 4, a fourth lens 5 and a display 6.

[0026] The display 6 is an organic electroluminescent device or a transmissive liquid crystal display 6, which is used to emit imaging light. The first lens 2, the second lens 3, the third lens 4 and the fourth lens 5 are all glass lenses. Specifically, the first lens 2, the second lens 3, the third lens 4 and the fourth lens 5 are arranged in sequence between the receiving end 1 and the display 6 along the direction from the receiving end 1 to the display 6; the first lens 2 and the fourth lens 5 are both meniscus lenses convex to the display 6 and with positive focal length, the second lens 3 is a double convex lens with positive focal length, the third lens 4 is a double concave lens with negative focal length, and the surface of the fourth lens 5 close to the display 6 is an even-order aspheric surface.

[0027] By setting the first lens 2 with positive optical power, it is beneficial to the light collection of the head-mounted display optical system, and the field of view can be effectively increased; by setting the second lens 3 with a positive optical angle and the third lens 4 with a negative optical power, the vertical axis chromatic aberration and position chromatic aberration of the head-mounted display optical system can be corrected; by setting the fourth lens 5 with positive optical power, it bears a larger optical power of the head-mounted display optical system, can change the propagation direction of the light beam, correct the aberration of the off-axis field of view, and is more conducive to the imaging of the light beam.

[0028] It can be understood that by setting the first lens 2, the second lens 3, the third lens 4 and the fourth lens 5, the light trend of the head-mounted display optical system can be smoothed, more light can be introduced to increase the field of view, and the aberration of the system can be effectively corrected, the distortion can be reduced, and the imaging quality can be improved. At the same time, by setting the shape of the lens group, the weight and volume of the head-mounted display optical system can be effectively reduced, the compactness of the optical system can be improved, and the user experience can be improved.

[0029] Furthermore, in one embodiment, the effective focal lengths of the first lens 2 , the second lens 3 , the third lens 4 and the fourth lens 5 are F1 , F2 , F3 and F4 respectively, and F1 , F2 and F4 are all positive values, and F3 is a negative value.

[0030] Specifically, the effective focal length of the head mounted display optical system is F, and satisfies: 1.47≤F1 / F≤1.83, 1.53≤F2 / F≤1.75, -1.71≤F3 / F≤-1.383, 0.23≤F4 / F≤0.27.

[0031] Furthermore, the refractive indices of the first lens 2, the second lens 3, the third lens 4 and the fourth lens 5 at the D line are respectively N1, N2, N3 and N4, and satisfy: 1.78≤N1≤1.82, 1.78≤N2≤1.86, 1.75≤N3≤1.85, 1.62≤N4≤1.89.

[0032] The Abbe numbers of the first lens 2, the second lens 3, the third lens 4 and the fourth lens 5 at the D line are V1, V2, V3 and V4 respectively, and satisfy: 35≤V1≤70, 35≤V2≤65, 20≤V3≤28, 18≤V4≤50.

[0033] The first lens 2 has a curvature radius R1 on a side close to the receiving end 1, and a curvature radius R2 on a side away from the receiving end 1; the second lens 3 has a curvature radius R3 on a side close to the receiving end 1, and a curvature radius R4 on a side away from the receiving end 1; the third lens 4 has a curvature radius R5 on a side close to the receiving end 1, and a curvature radius R6 on a side away from the receiving end 1; the fourth lens 5 has a curvature radius R7 on a side close to the receiving end 1, and satisfies: -62.5mm≤R1≤-51.7mm, -32.5mm≤R2≤-29mm, 78mm≤R3≤95mm, -143.32mm≤R4≤-115.8mm, -118.4mm≤R5≤-88mm, 95.27mm≤R6≤135.4mm, -55mm≤R7≤-37.6mm.

[0034] The even-order aspheric surface of the fourth lens 5 is a 10th-order aspheric surface. Specifically, the aspheric coefficients of the even-order aspheric surface of the fourth lens 5 include a quadratic surface coefficient a1, a fourth-order aspheric coefficient a2, a sixth-order aspheric coefficient a3, an eighth-order aspheric coefficient a4, and a tenth-order aspheric coefficient a5. In a preferred embodiment, a1 is -200.05, a2 is 9.551E-007, a3 is -3.16E-009, a4 is 1.2853E-012, and a5 is -2.347E-016.

[0035] Furthermore, the half field of view angle of the head-mounted display optical system is HFOV, and satisfies: 59°≤HFOV≤60°.

[0036] It can be understood that by setting the parameters of the first lens 2, the second lens 3, the third lens 4 and the fourth lens 5, the aberration of the system can be effectively corrected, the distortion can be reduced, the imaging quality can be improved, and the weight and volume of the head-mounted display optical system can be reduced, thereby improving the compactness of the optical system.

[0037] For details, please refer to Figure 2 ,Should Figure 2 is the spot diagram of the head mounted display optical system, Figure 2It can be seen from the information in the figure that the root mean square radius of the 12 fields of view in the figure are 30.880um, 31.800um, 31.332um, 27.243um, 26.910um, 30.160um, 31.920um, 31.585um, 29.241um, 28.004um, 26.912um, and 25.414um, which are all smaller than the size of two pixels and can be accepted by the human eye.

[0038] Please refer to Figure 3 ,Should Figure 3 is the field curvature and distortion curve of the head-mounted display optical system, Figure 3 It can be seen from the information that the field curvature of the head-mounted display optical system is less than 1.2mm, and the distortion value within the full field of view does not exceed 22%, which meets the design requirements.

[0039] Please refer to Figure 4 ,Should Figure 4 is the transfer function curve of the head-mounted display optical system, Figure 4 It can be seen from the information that the overall imaging quality of the head-mounted display optical system is good. Under the full field of view, the transfer function value of the head-mounted display optical system is as low as 0.2 at 15lp / mm, which meets the image quality requirements.

[0040] In summary, the head-mounted display optical system provided by the present application can make the light trend of the head-mounted display optical system smooth by setting the first lens 2, the second lens 3, the third lens 4 and the fourth lens 5, and can introduce more light to increase the field of view, and effectively correct the aberration of the system, reduce distortion, and improve imaging quality. At the same time, by setting the shape of the lens group, the weight and volume of the head-mounted display optical system can be effectively reduced, the compactness of the optical system can be improved, and the user experience can be improved.

[0041] The following is the content of the second aspect of the present invention:

[0042] The present invention provides a VR device, which includes the aforementioned head-mounted display optical system. Through the head-mounted display optical system, the VR device has good processability, and while obtaining relatively good imaging quality, the weight and volume of the VR device can be effectively reduced, which can effectively improve the user experience.

[0043] The above is only a specific implementation method of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A head-mounted display optical system, characterized in that: The invention comprises a receiving end, a first lens, a second lens, a third lens, a fourth lens and a display; the first lens, the second lens, the third lens and the fourth lens are sequentially arranged between the receiving end and the display along the direction from the receiving end to the display; the first lens and the fourth lens are both meniscus lenses convex toward the display and having positive optical focal length, the second lens is a double convex lens with positive optical focal length, the third lens is a double concave lens with negative optical focal length, and the surface of the fourth lens close to the display is an even-order aspheric surface.

2. The head mounted display optical system according to claim 1, characterized in that: The effective focal lengths of the first lens, the second lens, the third lens and the fourth lens are F1, F2, F3 and F4 respectively, and F1, F2 and F4 are all positive values, and F3 is a negative value.

3. The head mounted display optical system according to claim 2, characterized in that: The effective focal length of the head mounted display optical system is F, and satisfies: 1.47≤F1 / F≤1.83, 1.53≤F2 / F≤1.75, -1.71≤F3 / F≤-1.383, 0.23≤F4 / F≤0.

27.

4. The head mounted display optical system according to claim 1, characterized in that: The refractive indexes of the first lens, the second lens, the third lens and the fourth lens at the D line are N1, N2, N3 and N4 respectively, and satisfy: 1.78≤N1≤1.82, 1.78≤N2≤1.86, 1.75≤N3≤1.85, 1.62≤N4≤1.

89.

5. The head mounted display optical system according to claim 1, characterized in that: The Abbe numbers of the first lens, the second lens, the third lens and the fourth lens at the D line are V1, V2, V3 and V4 respectively, and satisfy: 35≤V1≤70, 35≤V2≤65, 20≤V3≤28, 18≤V4≤50.

6. The head mounted display optical system according to claim 1, characterized in that: The half field of view angle of the head mounted display optical system is HFOV, and satisfies: 59°≤HFOV≤60°.

7. The head mounted display optical system according to claim 1, characterized in that: The curvature radius of the first lens close to the receiving end is R1, and the curvature radius of the second lens away from the receiving end is R2; the curvature radius of the second lens close to the receiving end is R3, and the curvature radius of the second lens away from the receiving end is R4; the curvature radius of the third lens close to the receiving end is R5, and the curvature radius of the third lens away from the receiving end is R6; the curvature radius of the fourth lens close to the receiving end is R7, and the following conditions are satisfied: -62.5mm≤R1≤-51.7mm, -32.5mm≤R2≤-29mm, 78mm≤R3≤95mm, -143.32mm≤R4≤-115.8mm, -118.4mm≤R5≤-88mm, 95.27mm≤R6≤135.4mm, -55mm≤R7≤-37.6mm.

8. The head mounted display optical system according to claim 1, characterized in that: The even-order aspheric surface of the fourth lens is a 10th-order aspheric surface.

9. The head mounted display optical system according to claim 1, characterized in that: The first lens, the second lens, the third lens and the fourth lens are all glass lenses.

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

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