CN209895071U - An optical lens for virtual reality helmets - Google Patents

Abstract

The utility model discloses an optical lens for a virtual reality helmet, which is a three-piece lens group structure. A lens and a second lens, the third lens for correcting distortion and dispersion, the optical lens and the display screen are placed in front of the human eye in turn. The lens is made of injection-molded material, which reduces the weight and cost of the helmet. The optical system has a magnification of 5 to 7 times, a full field of view of 80 degrees, and a maximum distortion of less than 11%. Smaller magnification satisfies lower resolution screens, and users can get a good sense of immersion when using ordinary mobile phones.

Description

An optical lens for virtual reality helmets

technical field

The utility model relates to an optical system, in particular to an optical lens used for virtual reality.

Background technique

Virtual Reality (VR) technology is a computer-generated, interactive and immersive visual virtual environment proposed in the 1980s. It can generate a variety of virtual environments as needed and is widely used in urban planning. , driving training, interior design and other fields. In recent years, with the continuous improvement of computer computing power and the development of sensor technology, various types of virtual reality helmets have appeared on the market, which basically consist of a display screen or a mobile phone and a pair of eyepieces. The human eye can see the display screen through the eyepieces. On the enlarged image, the sensor senses the change of the human head and adjusts the image in the left and right display screens, so that the human eye can see a three-dimensional and interactive visual image.

At present, most of the virtual reality display systems use a single-chip or two-chip structure. The single-chip structure has the shortcomings of a small field of view and an unsatisfactory image quality. The need for immersion and experience in virtual reality.

SUMMARY OF THE INVENTION

Aiming at the deficiencies of the prior art, the utility model provides an optical lens for a virtual reality helmet, which has a specific large field of view and high edge field of view image quality and can realize a highly immersive virtual reality experience.

The technical solution for realizing the purpose of the present invention is to provide an optical lens for a virtual reality helmet, which is a three-piece lens group structure, along the optical axis from the object side to the image side in sequence, a first lens, a second lens and a third lens. Three lenses; the lens group satisfies the conditions: d>9mm, l>17mm, FOV= 80°, where d is the entrance pupil diameter, l is the exit pupil distance, and FOV is the full field of view; 0.6<f/f1< 0.8, 1.3<f/f2<1.42, -2.1<f/f3<-1.8, f is the total focal length of the optical lens, f1, f2 and f3 are the focal lengths of the first lens, the second lens and the third lens in sequence;

The first lens has a positive refractive power, and its object side (S1) and image side (S2) are spherical;

The second lens has a positive refractive power, and its object side (S3) and image side (S4) are both aspherical;

The third lens has negative refractive power, and at least one of its object side (S5) and image side (S6) is aspheric, and the other is aspheric or spherical;

The second lens satisfies the conditions: 38.5°≤arctan(SAG22/D22)≤40.5°, 38.5°≤arctan(SAG21/D21)≤40.5°; D22 is the semi-diameter of the maximum clear aperture of the image side, SAG22 is the sag of the image side at the vertex curvature, D21 is the semi-diameter of the maximum clear aperture of the object side, and SAG21 is the sag of the object side at the vertex curvature;

The third lens satisfies the conditions: 37.5°≤arctan(SAG32/D32)≤39.5°, 37.5°≤arctan(SAG31/D31)≤39.5°; D32 is the semi-aperture of the maximum clear aperture on the image side, and SAG32 is the image The sag height of the side face at the maximum half aperture, D31 is the half aperture of the maximum clear aperture of the object side, and SAG31 is the sag height of the object side at the maximum half aperture.

The optical lens provided by the utility model satisfies the conditions: 0.85≤T1/T3≤1, 0.14≤T2/T1≤0.15, 1.2≤TTL/EFL≤1.5; wherein, T1 is the distance between the object side of the first lens and the human eye The separation distance on the optical axis, T2 is the distance from the center of the image side of the second lens to the center of the object side of the third lens on the optical axis, T3 is the center of the image side of the third lens to the center of the display screen of the optical lens The distance on the optical axis, TTL is the distance from the center of the object side surface of the first lens to the center of the display screen of the optical lens on the optical axis, and EFL is the total effective focal length of the optical lens.

The total length of the optical lens is less than or equal to 90mm.

The optical system provided by the utility model has larger exit pupil diameter and exit pupil distance, so that the human eye can have a large space for movement during use.

Compared with the prior art, in the optical lens of the three-piece lens group structure provided by the present invention, the first lens and the second lens are used to correct the on-axis aberration and the off-axis aberration, and the third lens is used to correct the axial aberration. Distortion and dispersion, the optical lens and the display screen are placed in front of the human eye in turn. Compared with the two-piece structure, the three-piece structure can better correct chromatic aberration, obtain a larger field of view, and can correct a wider range of diopter; compared with the four-piece or five-piece structure, the three-piece structure The structure has less distortion, less volume, and less weight. The lens adopts injection molding material, which reduces the weight and cost of the helmet, lowers the manufacturing cost and lowers the processing difficulty. Therefore, the three-piece structured optical lens provided by the present invention utilizes lenses with different focal lengths to correct aberrations to obtain better imaging quality, and can also achieve smaller distortion in the case of a larger field of view. For virtual reality helmets, a larger field of view and better image quality can be obtained, and the image quality of the edge field of view is very high. The magnification of the optical system provided by the utility model is 5 to 7 times, the full field of view angle is 80 degrees, and the maximum distortion is less than 11%. Smaller magnification satisfies lower resolution screens, and users can get a higher sense of immersion.

Description of drawings

1 is a schematic structural diagram of an optical lens provided in Embodiment 1 of the present invention;

2 is a chromatic aberration diagram of the optical lens provided by Embodiment 1 of the present invention;

3 is a field curvature diagram of the optical lens provided by Embodiment 1 of the present invention;

4 is a distortion diagram of the optical lens provided by Embodiment 1 of the present invention;

5 is a modulation transfer function diagram of the optical lens provided in Embodiment 1 of the present invention;

6 is a schematic structural diagram of an optical lens provided in Embodiment 2 of the present invention;

7 is a chromatic aberration diagram of the optical lens provided by Embodiment 2 of the present invention;

8 is a field curvature diagram of an optical lens provided by Embodiment 2 of the present invention;

9 is a distortion diagram of an optical lens provided by Embodiment 2 of the present utility model;

10 is a modulation transfer function diagram of the optical lens provided in Embodiment 2 of the present utility model;

In the figure, 1. the first lens; 2. the second lens; 3. the third lens.

Detailed ways

The technical solutions of the present utility model are described in detail below with reference to the accompanying drawings and embodiments. In the description of the specification, many specific details are provided for a more complete understanding of the present invention; however, the present invention may be practiced without some or all of these specific details.

Example 1

Referring to FIG. 1 , it is a schematic structural diagram of the optical lens (referred to as OL1 ) provided in this embodiment. In order to show the features of this embodiment, only structures related to this embodiment are shown, and other structures are omitted. The optical system provided in this embodiment can be a wide-angle eyepiece with a wide-angle level greater than 80 degrees, which can be applied to a virtual reality helmet display system. It can be applied to the virtual reality helmet display system with the display screen of Iphone 6Plus. This embodiment is a fixed-focus optical system.

As shown in FIG. 1 , the optical lens OL1 of this embodiment mainly includes in order from the object side to the image side: a first lens 1 with positive refractive power, a second lens 2 with positive refractive power, and a first lens 2 with positive refractive power Triple lens 3.

In this embodiment, the display screen is placed on the image side of the optical lens, and the human eye is located on the object side of the optical lens.

In this embodiment, the corresponding display screen of the optical lens is an Apple 6P mobile phone screen with a width of 69mm and a length of 122mm, or a display screen of the same size with a screen resolution greater than 1300*650 pixels.

In the optical lens provided in this embodiment, the front and rear surfaces of the second lens 2 are aspherical, the front surface of the third lens 3 is aspherical, and the rear surface is aspherical. Aspheric surfaces can satisfy the following mathematical formulas:

；

;

Among them, z is the surface sag, r is the vertical distance from the surface vertex to any point on the surface, c is the curvature of the surface vertex, k is the surface conic coefficient, and α ₁ to α ₈ are the first to eighth aspheric coefficients, respectively.

Table 1 lists the detailed data of the optical lens OL1 as shown in FIG. 1 according to the content of the present invention, which includes the curvature radius, thickness, refractive index, dispersion coefficient, etc. of each lens. Among them, the surface codes of the lens are arranged in order from the object side to the image side, S1 is the surface of the first lens 1 facing the object side, S2 is the surface of the first lens 1 facing the image side, and similarly, S3 and S5 are the second The surfaces of the lens 2 and the third lens 3 facing the object side, S4 and S6 are the surfaces of the second lens 2 and the third lens 3 facing the image side, respectively. In Table 1, "thickness" represents the distance between the surface and a surface adjacent to the image side. For example, the "thickness" of surface S1 is the distance between surface S1 and surface S2, and the "thickness" of surface S2 is surface S2 and surface S3 the distance.

Table 1

Table 2 shows the coefficients of the two surfaces S3 and S4 of the second lens 2 and the first surface S5 of the third lens 3 in this embodiment.

Table 2

surface Conic factor A2 A4 A6 A8 A10 A12 A14 A16 S3 -0.946 1.225E-03 -3.459E-06 -6.392E-09 -7.743E-12 -1.589E-15 1.179E-17 2.604E-20 -2.021E-23 S4 -7.623 -8.282E-03 -7.427E-07 1.514E-09 -1.793E-12 -4.720E-15 -3.889E-18 4.511E-21 3.236E-23 S5 -2.872 -5.027E-03 8.451E-06 6.078E-09 -1.360E-12 -5.143E-15 3.485E-19 1.205E-20 -7.598E-24

Referring to FIG. 2, it is a vertical axis colordifference curve diagram of the optical lens provided in this embodiment. The figure shows that the vertical axis chromatic aberration is less than 32μm.

Referring to FIG. 3, it is a field curvature curve diagram of the optical lens provided by this embodiment. The graph shows that the tangent and sag values of the beams with wavelengths of 480nm, 515nm, 546nm and 640nm are well controlled.

Referring to FIG. 4, it is a distortion curve diagram of the optical lens provided in this embodiment. The figure shows that the distortion rates of the beams with wavelengths of 486nm, 588nm and 656nm are all controlled within the range of (-11%, +11%).

Referring to FIG. 5, it is an FFT MTF curve diagram of the optical lens provided in this embodiment. The figure shows that the FFT MTF of the beam at each field of view is above 0.2 at 10 line pairs/mm, and all are controlled within a good range.

Example 2

Referring to FIG. 6 , it is a schematic structural diagram of the optical lens (denoted as OL2 ) provided in this embodiment. In order to show the features of this embodiment, only structures related to this embodiment are shown, and other structures are omitted. The optical lens provided in this embodiment can be a wide-angle eyepiece with a wide-angle level greater than 80 degrees, which can be applied to a virtual reality helmet display system, and is suitable for a virtual reality helmet display system with a Samsung Galaxy Note9 display screen. This embodiment provides a fixed-focus optical system. The optical lens OL2 mainly includes in sequence from the object side to the image side: a first lens 1 with positive refractive power, a second lens 2 with positive refractive power, and a third lens 3 with positive refractive power. In this embodiment, the display screen is placed on the image side of the optical lens, the human eye is located on the object side of the optical lens, the distance between the human eye and the first lens 1 of the optical lens is 20mm, and the center of the human eye can be decentered by 4mm from the optical axis .

The display screen corresponding to the optical lens OL2 provided in this embodiment is a Samsung Galaxy Note9 mobile phone screen with a width of 76.4mm and a length of 161.9mm, or a display screen of the same size with a screen resolution greater than 1300*650 pixels.

The front and rear surfaces of the second lens 2 of the optical lens OL2 are both aspherical, the front surface of the third lens 3 is aspherical, and the rear surface is aspherical. Aspheric surfaces can satisfy the following mathematical formulas:

；

;

Among them, z is the surface sag, r is the vertical distance from the surface vertex to any point on the surface, c is the curvature of the surface vertex, k is the surface conic coefficient, and α ₁ α ₈ are the first to eighth aspheric coefficients, respectively.

Table 3 lists the detailed data of the embodiment of the optical lens OL2 as shown in FIG. 2 according to the content of the present invention, which includes the curvature radius, thickness, refractive index, dispersion coefficient, etc. of each lens. The surface codes of the lenses are arranged in sequence from the object side to the image side, S1 is the surface of the first lens 1 facing the object side, S2 is the surface of the first lens 1 facing the image side, and similarly, S3 and S5 are the second lenses respectively 2 and the surfaces of the third lens 3 facing the object side, S4 and S6 are the surfaces of the second lens 2 and the third lens 3 facing the image side, respectively. "Thickness" represents the distance between the surface and a surface adjacent to the image side. For example, the "thickness" of surface S1 is the distance between surface S1 and surface S2, and the "thickness" of surface S2 is the distance between surface S2 and surface S3.

table 3

In the present embodiment, the two surfaces S3 and S4 of the second lens 2 and the first surface S5 of the third lens 3 have various coefficients in the aspherical mathematical formula as shown in Table 4.

Table 4

surface Conic factor A2 A4 A6 A8 A10 A12 A14 A16 S3 -1.949 2.649-E03 -3.266E-06 -8.763E-10 3.981E-13 1.378E-15 7.137E-19 7.304E-22 -4.750E-25 S4 -6.135 -9.667E-03 -3.875E-06 4.957E-10 -4.179E-13 1.658E-16 1.385E-18 6.019E-22 1.141E-24 S5 -4.525 -4.862E-03 6.255E-06 3.735E-09 -4.061E-13 -2.339E-15 -9.325E-19 1.461E-21 6.127E-25

Referring to FIG. 7 , a vertical axis chromatic aberration (Vertical axis colordifference) curve diagram of the optical lens OL2 provided in this embodiment. The figure shows that the vertical axis chromatic aberration is less than 40μm.

Referring to FIG. 8, a field curvature curve diagram of the optical lens OL2 provided in this embodiment. The figure shows that the tangent and sag values of the beams with wavelengths of 486nm, 588nm and 656nm are well controlled.

Referring to FIG. 9, a distortion curve diagram of the optical lens OL2 provided in this embodiment. The figure shows that the distortion rates of the beams with wavelengths of 486nm, 588nm and 656nm are all controlled within the range of (-11%, +11%).

Referring to FIG. 10, the FFT MTF curve diagram of the optical lens OL2 provided in this embodiment. The figure shows that the FFT MTF of the beam at each field of view is above 0.3 at 10 line pairs/mm, and all are controlled within a good range.

Claims (3)

1. An optical lens for a virtual reality helmet, characterized in that: it is a three-piece lens group structure, and along the optical axis from the object side to the image side are a first lens (1), a second lens (2) and the third lens (3); the lens group satisfies the conditions: d>9mm, l>17mm, FOV= 80°, where d is the entrance pupil diameter, l is the exit pupil distance, and FOV is the full field of view; 0.6 <f/f1<0.8, 1.3<f/f2<1.42, -2.1<f/f3<-1.8, where f is the total focal length of the optical lens, f1, f2 and f3 are the first lens, the second lens and the The focal length of the third lens; The first lens has a positive refractive power, and its object side (S1) and image side (S2) are spherical; The second lens has a positive refractive power, and its object side (S3) and image side (S4) are both aspherical; The third lens has a negative refractive power, and at least one of its object side (S5) and image side (S6) is aspheric, and the other is aspheric or spherical; The second lens satisfies the conditions: 38.5°≤arctan(SAG22/D22)≤40.5°, 38.5°≤arctan(SAG21/D21)≤40.5°; D22 is the semi-aperture of the maximum clear aperture of the image side, SAG22 is the sag of the image side at the vertex curvature, D21 is the semi-diameter of the maximum clear aperture of the object side, and SAG21 is the sag of the object side at the vertex curvature; The third lens satisfies the conditions: 37.5°≤arctan(SAG32/D32)≤39.5°, 37.5°≤arctan(SAG31/D31)≤39.5°; D32 is the semi-aperture of the maximum clear aperture on the image side, and SAG32 is the image The sag height of the side face at the maximum half aperture, D31 is the half aperture of the maximum clear aperture of the object side, and SAG31 is the sag height of the object side at the maximum half aperture. 2. An optical lens for a virtual reality helmet according to claim 1, characterized in that: it satisfies the conditions: 0.85≤T1/T3≤1, 0.14≤T2/T1≤0.15, 1.2≤TTL/EFL≤ 1.5; wherein, T1 is the distance between the object side of the first lens and the human eye on the optical axis, T2 is the distance from the center of the image side of the second lens to the center of the object side of the third lens on the optical axis, and T3 is The distance from the center of the image side of the third lens to the center of the display screen of the optical lens on the optical axis, TTL is the distance from the center of the object side of the first lens to the center of the display screen of the optical lens on the optical axis, EFL is the optical axis The total effective focal length of the lens. 3. An optical lens for a virtual reality helmet according to claim 1, characterized in that: its total length≤90mm.

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