WO2018113623A1

WO2018113623A1 - Lens module

Info

Publication number: WO2018113623A1
Application number: PCT/CN2017/116906
Authority: WO
Inventors: 李方方; 李炜
Original assignee: 深圳市掌网科技股份有限公司
Priority date: 2016-12-21
Filing date: 2017-12-18
Publication date: 2018-06-28
Also published as: CN108227190A; CN108227190B

Abstract

A lens module, for being installed between a human eye pupil (STO) and a screen (IMA). The screen (IMA) is used for displaying a virtual reality image. The lens module comprises a crescent lens (L1) and a lens group composed of a lenticular lens (L2) and a biconcave lens (L3) provided in order in the direction from the human eye pupil (STO) to the screen (IMA). The concave surface of the crescent lens (L1) faces the human eye pupil (STO). The focal power of the crescent lens (L1) is positive, the focal power of the lenticular lens (L2) is positive, and the focal power of the biconcave lens (L3) is negative. The crescent lens (L1) and the biconcave lens (L3) are both aspherical lenses. The lens module is an ingenious design, and has a strong practicality.

Description

Lens module

Technical field

The present invention relates to the field of virtual reality, and in particular, to a lens module.

Background technique

Since Facebook acquired Oculus for $2 billion in 2014, global technology giants have invested in the VR field, setting off a wave of commercialization and popularization of VR. There are giants such as Oculus, Coogle, SONY, HTC, Samsung, and Microsoft. Incoming, domestic storm technology, LeTV, iQiyi, Tencent, Huawei and other companies also announced the entry into the VR field. Virtual reality technology is currently in a period of great explosion and rapid development. Whether it is the International Summit, or the domestic high-tech fair, the virtual reality technology is the hot topic of the past two years.

As a new general-purpose computing platform after PC and mobile Internet, VR platform opens the door to virtual world with superior immersion, natural friendly interaction and broad application prospects. VR is widely used, not only limited. In games, it can also be extended to other fields, including communication, media and entertainment, education, etc., to change or even subvert the way people work, play and communicate.

Although VR technology is not yet very mature, it can already experience the initial products of VR. The parameters such as field of view, resolution and delay have a direct impact on the experience. From the initial entry-level Google Cardboard to Samsung Gear and HTC VIVE, the performance of VR products continues to increase and the functions are getting stronger and stronger. The resolution of the latest generation Oculus Rift is 2160×1200 pixels (two screens), the field of view. 110 °, refresh rate 90Hz, the newly released 3glasses Lanper s1 resolution 2880 * 1440 (two screens), the field of view angle of 110 °, the highest refresh rate of 120 Hz, the above is the physical parameters of the product. It can be found that the current field of view of VR products is generally between 90° and 110°, and since VR glasses use more monolithic lenses on the optical structure, the parameters that can be used for optimization are extremely limited, and the conditions for clarity are met. Under the angle of view, the field of view cannot be increased. In addition, the large field of view aberrations are not effectively corrected, resulting in poor imaging performance. The general center image is clear, the surrounding is bad or even blurred, which directly affects the effect. fruit.

Summary of the invention

The present invention is directed to the use of a single-piece lens in the optical structure of the existing VR glasses, and the parameters that can be used for optimization are extremely limited, and the field of view angle cannot be increased in the case of satisfying the definition requirement, and the large field of view aberration is also Failure to obtain effective correction results in poor imaging performance. The general center image is clear, the surrounding is not good or even blurred, and directly affects the experience effect. A lens module is proposed.

The technical solution proposed by the present invention on the technical problem is as follows:

The invention provides a lens module for being arranged between a human eye pupil and a screen for displaying a virtual reality picture; the lens module comprises a crescent lens arranged in a direction along the pupil of the human eye to the screen, and a lens group consisting of a lenticular lens and a biconcave lens; the concave surface of the crescent lens faces the pupil of the human eye; the power of the crescent lens is positive, the power of the lenticular lens is positive, and the power of the biconcave lens is negative; Both the lunar lens and the biconcave lens are aspherical mirrors.

In the above lens module of the present invention, the lenticular lens and the biconcave lens are sequentially disposed in the direction of the pupil of the human eye to the screen.

In the above lens module of the present invention, the lenticular lens and the biconcave lens are sequentially disposed in the direction of the screen to the pupil of the human eye.

In the above lens module of the present invention, the crescent lens and the biconcave lens satisfy the following relationship: -1.69 < f1/f3 < -1.15, wherein f1 is the focal length of the crescent lens and f3 is the focal length of the biconcave lens.

In the above lens module of the present invention, the lenticular lens and the biconcave lens satisfy the relationship: -2.90 < f2 / f3 < - 1.92, wherein f2 is the focal length of the lenticular lens, and f3 is the focal length of the biconcave lens.

In the above lens module of the present invention, the crescent lens and the biconcave lens respectively satisfy the following aspherical formulas:

Where r is the distance from the point on the optical surface to the optical axis;

Z is the vector height of the point along the optical axis;

c is the curvature of the optical surface; c = 1 / r;

k is the quadratic constant of the optical surface, and A, B, C, D, E, and F are fourth-order, sixth-order, eighth-order, ten-order, twelve-order, and fourteenth-order high-order aspherical coefficients, respectively.

In the above lens module of the present invention, the aspherical mirror is made of a resin material.

In the above lens module of the present invention, the aspherical mirror is made of a glass material.

In the above lens module of the present invention, the screen is a curved surface.

The lens module proposed by the invention can effectively correct the distortion size, reduce the distortion and distortion of the image, and correct the spherical aberration and the system distortion by using the crescent lens with positive refractive power while expanding the angle of view of the lens. The lens group consisting of the lenticular lens L2 and the biconcave lens L3 can correct the system spherical aberration and astigmatism, and improve the imaging performance of the edge field of view. The lens module of the invention has a clever design and strong practicability.

DRAWINGS

The present invention will be further described below in conjunction with the accompanying drawings and embodiments, in which:

FIG. 1 is a schematic view showing a lens module according to an embodiment of the present invention; FIG.

2 is a MTF graph of a lens module having an angle of view of 100° according to an embodiment of the present invention;

3 is a MTF graph of a lens module having a viewing angle of 120° according to an embodiment of the present invention;

4 is a defocusing curve diagram of a lens module according to an embodiment of the present invention;

5 is a field curve diagram of a lens module according to an embodiment of the present invention;

FIG. 6 is a distortion diagram of a lens module according to an embodiment of the present invention.

detailed description

The technical solutions in the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, but not all embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

Referring to FIG. 1, FIG. 1 is a schematic diagram of a lens module according to an embodiment of the present invention. The lens module is arranged between the human eye pupil STO and the screen IMA, the screen IMA is used for displaying the virtual reality picture; the lens module comprises a crescent lens L1 arranged in the direction of the human eye pupil STO to the screen IMA. And a lens group composed of the lenticular lens L2 and the biconcave lens L3; the concave surface of the crescent lens L1 faces the human eye pupil STO; the power of the crescent lens L1 is positive, the power of the lenticular lens L2 is positive, and the biconcave lens L3 The refractive power is negative; the crescent lens L1 and the biconcave lens L3 are both aspherical mirrors. In the present technical solution, the human eye pupil STO is equivalent to an aperture stop.

In the above technical solution, by adopting the technical feature that the concave surface of the crescent lens L1 faces the human eye pupil STO and the power of the crescent lens L1 is positive, the distortion of the lens field of view angle can be effectively controlled, and the distortion can be effectively reduced. Image distortion and distortion can correct spherical aberration and system distortion.

By using the lenticular lens L2 with positive refractive power and the double concave lens L3 with negative refractive power, it is possible to correct system spherical aberration and astigmatism, and improve imaging performance of the edge field of view.

Further, the lenticular lens L2 and the biconcave lens L3 may be sequentially disposed in the direction of the human eye pupil STO to the screen IMA, or may be sequentially disposed in the direction of the screen IMA to the human eye pupil STO. Any of the above arrangements of the lens group can meet the imaging performance requirements. This embodiment adopts the former setting mode.

Further, since the aspherical mirror has greater freedom and flexibility, the present invention adopts the features of the crescent lens L1 and the biconcave lens L3 as aspherical mirrors, which can effectively correct aberrations and improve in the optimization process of the virtual reality image. Image quality, improved optical performance, and ability to match high-resolution 2K or even higher resolution display screens.

Further, the aspherical mirror is made of a resin material; in order to create a deep immersion, the aspherical mirror has a large caliber in actual use; considering the weight and comfort of the head-mounted product, the lens made of a resin material can make the weight lighter. At the same time, the use of a multi-hole manufacturing method can increase the production rate and reduce the production cost. It can be understood that the aspherical mirror can also be made of a glass material or other transparent materials.

Further, the crescent lens L1 and the biconcave lens L3 satisfy the following relationship: -1.69 < f1/f3 < - 1.15, where f1 is the focal length of the crescent lens L1, and f3 is the focal length of the biconcave lens L3.

Further, the lenticular lens L2 and the biconcave lens L3 satisfy the relationship: -2.90 < f2 / f3 < - 1.92, where f2 is the focal length of the lenticular lens L2, and f3 is the focal length of the biconcave lens L3.

Further, when the lens module has field curvature, the intersection of the beams passing through the lens module does not coincide with the ideal image point, and although a clear image point is obtained at each specific point, the entire image plane is a Surface. At the time of use, the human eye cannot simultaneously see the various positions of the virtual display screen: when the center image is clear, the edges are blurred, or the edges are clear and the center is blurred, which causes difficulties for the observer. In this embodiment, the screen IMA is a curved surface; by using a curved screen IMA, it can effectively help us correct the curvature of field, so that the center and edge fields of view can be clearly imaged at the same time.

Further, the optical parameters used in this embodiment are as follows:

Entrance pupil diameter (EPD, Entrance Pupil Diameter): 5 mm; effective focal length: 35 mm; distance from the entrance to the nearest lens surface (Eye relief): 10 mm;

	KK	AA	BB	CC	DD	EE	FF
S2S2	4.194.19	-3.35E-05-3.35E-05	2.46E-072.46E-07	-6.88E-10-6.88E-10	1.00E-121.00E-12	-4.10E-16-4.10E-16	0.00E+000.00E+00
S3S3	-0.63-0.63	7.96E-067.96E-06	-3.75E-08-3.75E-08	-2.42E-11-2.42E-11	4.05E-134.05E-13	3.67E-163.67E-16	0.00E+000.00E+00
S6S6	-7.65-7.65	6.86E-066.86E-06	-1.39E-08-1.39E-08	1.33E-111.33E-11	-4.80E-15-4.80E-15	-6.88E-19-6.88E-19	0.00E+000.00E+00
S7S7	-7.47-7.47	4.17E-064.17E-06	-8.28E-09-8.28E-09	7.71E-127.71E-12	-1.67E-15-1.67E-15	-7.78E-19-7.78E-19	0.00E+000.00E+00

Wherein, S1 is the aperture pupil plane (the face of the human eye pupil STO); S2 is the surface of the crescent lens L1 facing the human eye pupil STO; S3 is the surface of the crescent lens L1 facing the screen IMA; S4 is the lenticular lens L2 S5 is the surface of the human eye pupil STO; S5 is the surface of the lenticular lens L2 facing the screen IMA; S6 is the surface of the biconcave lens L3 facing the human eye pupil STO; S7 is the surface of the biconcave lens L3 facing the screen IMA; IMA is the screen The location of the IMA.

The crescent lens L1 and the biconcave lens L3 are aspherical mirrors that respectively satisfy the following aspherical formulas:

Z is the vector height of the point along the optical axis;

c is the curvature of the optical surface; c = 1 / r;

k is the quadratic constant of the optical surface, and A, B, C, D, E, and F are respectively fourth order, Sixth, eighth, tenth, twelveth, and fourteenth order high order aspheric coefficients. With the scheme of the embodiment, the VR large field of view angle can be realized, and the full field of view range is clearly imaged, giving everyone a clearer and deeper immersive experience.

2 to 6 are graphs showing optical performance of an embodiment of the present invention. 2 is a MTF (modulation transfer function) graph of a lens module having an angle of view of 100° according to an embodiment of the present invention; and FIG. 3 is a lens module having an angle of view of 120° according to an embodiment of the present invention; MTF (Modulation Transfer Function) graph; Modulation Transfer Function (MTF) is the most reliable method for judging the performance of optical systems, especially for lens modules; MTF is defined as a certain spatial frequency, between the actual image and the ideal image. The ratio of the system to the relative spatial frequency. The abscissa of the MTF curve is the spatial frequency lp/mm (line pair/mm), the detail information corresponds to the high frequency, and the contour information corresponds to the low frequency. The ordinate is the contrast (%), and the higher the curve, the better the image quality. Since the contrast of the actual image is always less than the contrast of the input image, the value of the MTF is between 0-1. The different curves in Figures 2 and 3 represent the image heights corresponding to different fields of view, and T and S represent the MTF in the meridional direction and the sagittal direction, respectively. It can be seen from the MTF curves of Figs. 2 and 3 that the image can be clearly seen in the entire field of view. Optimized according to the optical path structure, it can match the display screen with higher pixel resolution.

4 is a tow focus curve diagram of a lens module according to an embodiment of the present invention. The defocus curve indicates the relationship between the meridional, sagittal MTF and the defocus amount for different field of view of the set spatial frequency, and the abscissa in the figure. It is the amount of defocus, and the ordinate is the contrast. From this figure, we can see the consistency of the best focal plane of each field of view. Whether the MTF is sensitive to defocus. It can be seen from Fig. 4 that the best focal planes of the fields of view are basically the same, and the image quality of each field of view is uniform and clear.

5 is a field curve diagram of a lens module according to an embodiment of the present invention, which is obtained from wavelengths of three colors of F, d, C (F=0.486um, d=0.588um, C=0.656um) in a common visible light band. It is indicated that T and S respectively represent the meridional and sagittal directions, the ordinate is the field of view, the unit is the angle, and the abscissa is the curvature of field, the unit is millimeter (mm); FIG. 6 is the distortion curve of the lens module according to the embodiment of the present invention. The ordinate is the field of view and the abscissa is the percentage of distortion. The distortion curve represents the magnitude of the distortion in the case of different angles of view, in %. Therefore, as can be seen from FIG. 2 to FIG. 6, the optical lens has corrected various aberrations to a good degree, and the full field of view range can be clearly imaged.

It should be understood that those skilled in the art can improve upon the above description. All changes and modifications are intended to be included within the scope of the appended claims.

Claims

A lens module for setting between a human eye pupil (STO) and an screen (IMA), an image (IMA) for displaying a virtual reality picture; and a lens module including a pupil hole along the human eye (STO) a crescent lens (L1) arranged in turn in the direction of the screen (IMA) and a lens group consisting of a lenticular lens (L2) and a biconcave lens (L3); the concave surface of the crescent lens (L1) faces the pupil of the human eye (STO) The crescent lens (L1) has a positive power, the lenticular lens (L2) has a positive power, the biconcave lens (L3) has a negative power; the crescent lens (L1) and the biconcave lens (L3) All are aspherical mirrors.
The lens module according to claim 1, wherein the lenticular lens (L2) and the biconcave lens (L3) are sequentially disposed in a direction from a human eye pupil (STO) to a screen (IMA).
The lens module according to claim 1, wherein the lenticular lens (L2) and the double concave lens (L3) are sequentially disposed in a direction from the screen (IMA) to the pupil of the human eye (STO).
The lens module according to claim 1, wherein the crescent lens (L1) and the biconcave lens (L3) satisfy the following relationship: -1.69 < f1/f3 < -1.15, wherein f1 is a crescent lens ( The focal length of L1), f3 is the focal length of the biconcave lens (L3).
The lens module according to claim 1, wherein the lenticular lens (L2) and the biconcave lens (L3) satisfy a relationship of -2.90 < f2 / f3 < - 1.92, wherein f2 is a lenticular lens (L2) The focal length, f3 is the focal length of the double concave lens (L3).
The lens module according to claim 1, wherein the crescent lens (L1) and the biconcave lens (L3) respectively satisfy the following aspherical formula:

Where r is the distance from the point on the optical surface to the optical axis;

Z is the vector height of the point along the optical axis;

c is the curvature of the optical surface; c = 1 / r;

k is the quadratic constant of the optical surface, and A, B, C, D, E, and F are fourth-order, sixth-order, eighth-order, ten-order, twelve-order, and fourteenth-order high-order aspherical coefficients, respectively.
The lens module according to claim 1, wherein the aspherical mirror is made of a resin material.
The lens module according to claim 1, wherein the aspherical mirror is made of a glass material.
The lens module according to claim 1, wherein the screen (IMA) is a curved surface.