Optical system and vr glasses

Abstract

The application discloses an optical system and a VR glasses, the optical system has an object side and an image side which are oppositely arranged along the extension direction of the optical axis, and comprises a first lens, a second lens and a third lens which are sequentially arranged from the image side to the object side, wherein: the first lens is coated with a half-reflective and half-transmissive film on the end face close to the image side, and is coated with an AR (anti-reflective) film on the end face close to the object side; the second lens is coated with an AR film on the end face close to the image side, and is glued with a quarter-wave plate film on the end face close to the object side, and the end face of the quarter-wave plate film away from the second lens is glued with a linear polarization film; and the two end faces of the third lens close to the object side and the image side are both coated with an AR film. The application aims to provide an optical system with high image quality, a large field of view, a large aperture and less stray light, so that the user can obtain a better viewing effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical technology, in particular to the field of VR glasses, and more particularly to an optical system and VR glasses. BACKGROUND

[0002] With the development of display technology, virtual reality (VR) display technology has received extensive attention and gradually appeared in people's life and work. In the field of VR display, in order to make the VR device lighter and thinner, most technical personnel choose to adopt a pancake type folding optical path structure. The working principle of the traditional pancake folding optical path structure is as follows: the first linearly polarized light emitted by the screen passes through a first 1 / 4 wave plate QWP1 and becomes circularly polarized light. Then the circularly polarized light passes through a single lens or a lens group composed of multiple lenses, one surface of a lens in the lens group is provided with a partial reflection film. The light transmits through the lens and is depolarized from circularly polarized light to elliptically polarized light due to the birefringence effect of the lens, but the elliptically polarized light is close to circularly polarized light. Then the elliptically polarized light passes through a second 1 / 4 wave plate QWP2 and becomes elliptically polarized light close to the second linearly polarized light. In this process, if the light is not depolarized, it should be the second linearly polarized light perpendicular to the transmission axis of the polarization reflection piece PBS, then the light will be fully reflected by the PBS, but the light depolarized to elliptically polarized light will have part of the light transmitting through the PBS to form a ghost. The remaining light is reflected back and becomes the second linearly polarized light. Then the second linearly polarized light reflected back by the PBS passes through the QWP2 and becomes circularly polarized light. Then the circularly polarized light passes through the lens and is reflected by the partial reflection film, and then passes through the lens again, becomes elliptically polarized light close to circularly polarized light, and then passes through the QWP2 to become elliptically polarized light close to the third linearly polarized light. At this time, most of the light can transmit through the PBS to form a main image, and the remaining light is reflected back by the PBS, causing loss of effective light. This structure can greatly reduce the thickness of the VR optical structure, but it also brings serious stray light, ghosting and other adverse effects, which affect the viewing effect of the user. SUMMARY

[0003] The main purpose of the present application is to provide an optical system and VR glasses, which can provide an optical system with high image quality, large field of view, large aperture and less stray light, so that the user can have a better viewing effect.

[0004] To achieve the above purpose, the present application provides an optical system, which has an object side and an image side arranged opposite along the extension direction of the optical axis, and comprises a first lens, a second lens and a third lens arranged in sequence from the image side to the object side, wherein:

[0005] The end face close to the image side of the first lens is coated with a semi-reflective and semi-transmissive film, and the end face close to the object side is coated with an AR transparent film.

[0006] The second lens is coated with an AR anti-reflection film on an end face close to the image side, and a quarter-wave film is glued on an end face close to the object side, and a linearly polarized film is glued on the end face of the quarter-wave film away from the second lens;

[0007] Both end faces of the third lens close to the object side and the image side are coated with an AR anti-reflection film.

[0008] Optionally, the first lens has a positive refractive power; and / or,

[0009] The second lens has a negative refractive power; and / or,

[0010] The third lens has a positive refractive power.

[0011] Optionally, the first lens has a swelling coefficient P1, 50 < P1 < 70; and / or,

[0012] The second lens has a swelling coefficient P2, 50 < P2 < 70; and / or,

[0013] The third lens has a swelling coefficient P3, 50 < P3 < 70.

[0014] Optionally, the first lens, the second lens and the third lens are all aspherical lenses; and / or,

[0015] At least one of the first lens, the second lens and the third lens is made of a plastic material.

[0016] Optionally, the surface shape of the aspherical surface of any one of the first lens, the second lens and the third lens satisfies formula I, and formula I is

[0017]

[0018] wherein c is the curvature corresponding to the radius, y is the radial coordinate, k is the conic quadratic curve coefficient, and a1 to a8 are coefficients corresponding to each radial coordinate.

[0019] Optionally, the light ray of the image side passes through the first lens, the second lens and the quarter-wave film in sequence, is reflected by the linearly polarized film to form reflected light;

[0020] The reflected light passes through the quarter-wave film, the second lens and the first lens in sequence, is reflected by the half-reflection half-transmission film on the end face of the first lens close to the image side to form secondary reflected light;

[0021] The secondary reflected light passes through the first lens, the second lens, the quarter-wave plate film, the linear polarization film and the third lens in turn to reach the object side.

[0022] Optionally, the polarization state between the quarter-wave plate film and the image side is clockwise circular polarization, and the polarization state between the quarter-wave plate film and the linear polarization film is vertical linear polarization.

[0023] Optionally, the polarization state between the linear polarization film and the first lens is counterclockwise circular polarization.

[0024] Optionally, the polarization state between the first lens and the quarter-wave plate film is counterclockwise circular polarization, and the polarization state between the quarter-wave plate film and the object side is horizontal linear polarization.

[0025] In addition, the application further provides a VR glasses, comprising an optical system, the optical system has an object side and an image side which are oppositely arranged along the extension direction of the optical axis, and the optical system comprises a first lens, a second lens and a third lens which are sequentially arranged from the image side to the object side, wherein:

[0026] The first lens is coated with a semi-reflective and semi-transmissive film on the end face close to the image side, and is coated with an AR transparent film on the end face close to the object side;

[0027] The second lens is coated with an AR anti-reflection film on the end face close to the image side, and is glued with a quarter-wave plate film on the end face close to the object side, and the quarter-wave plate film is glued with a linear polarization film on the end face away from the second lens;

[0028] The third lens is coated with an AR anti-reflection film on the two end faces close to the object side and the image side.

[0029] In the technical scheme provided by the present application, the light rays on the image side pass through the first lens, the second lens and the quarter-wave film in sequence, are reflected by the linear polarization film to form reflected light; the reflected light passes through the quarter-wave film, the second lens and the first lens in sequence, is reflected by the half-reflection half-transmission film on the end face of the first lens close to the image side to form secondary reflected light; and the secondary reflected light passes through the first lens, the second lens, the quarter-wave film, the linear polarization film and the third lens in sequence to reach the object side. In fact, in the propagation path of the light rays, by adding a phase compensation element on the light path between the lens module (i.e. the first lens, the second lens and the third lens) and the linear polarization film, the polarization compensation is performed on the polarized light transmitted between the lens module and the linear polarization film, so that the polarized light incident on the linear polarization film is the corresponding linearly polarized light. In this way, the light ray depolarization caused by the birefringence effect of the lens can be effectively compensated, the ghost can be eliminated, the light efficiency can be ensured, and thus the imaging quality is improved and the viewing effect of the user is improved. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only show some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained according to the structures shown in these drawings without creative labor.

[0031] Figure 1 Structure schematic diagram of an embodiment of the optical system provided by the present application;

[0032] Figure 2 MTF curve diagram of the optical system provided by the present application;

[0033] Figure 3 Distortion curve diagram of the optical system provided by the present application.

[0034] Explanation of reference numerals:

[0035] Reference Name Reference Name 100 Optical system 6 Clockwise circular polarization 1 First lens 7 Vertical linear polarization 2 Second lens 8 Horizontal linear polarization 3 Third lens 9 Counter-clockwise circular polarization 4 Quarter-wave plate film 10 Object side 5 Linear polarization film 20 Image side

[0036] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0037] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described, obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without creative labor fall within the protection scope of the present application.

[0038] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, motion condition, etc. between components in a certain posture (as shown in the drawings), and if the certain posture changes, the directional indications also change accordingly.

[0039] In addition, if the embodiments of the present application involve descriptions such as "first", "second", etc., the descriptions of "first", "second", etc. are only for description purposes, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features. In addition, the meaning of "and / or" appearing throughout the text includes three parallel solutions, for example, "A and / or B" includes A solution, or B solution, or A and B solutions. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the realization of a person of ordinary skill in the art, when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, and is not within the protection scope claimed by the present application.

[0040] With the development of display technology, virtual reality (VR) display technology has received extensive attention and gradually appears in people's life and work. In the field of VR display, in order to make the VR device lighter and thinner, most technicians choose to adopt a pancake type folding light path structure, which can greatly reduce the thickness of the VR optical structure, but also brings more serious stray light, forming ghosting and other adverse effects, affecting the viewing effect of users.

[0041] In view of this, the present application provides an optical system, Figure 1 An embodiment of the optical system provided by the present application is described below mainly in conjunction with specific drawings.

[0042] Please refer to Figure 1An optical system 100 has an object side and an image side arranged oppositely along the extension direction of an optical axis, and comprises a first lens 1, a second lens 2 and a third lens 3 arranged in sequence from the image side to the object side, wherein: the first lens 1 is coated with a half-reflective half-transmissive film on an end face close to the image side and is coated with an AR (anti-reflective) film on an end face close to the object side; the second lens 2 is coated with an AR film on an end face close to the image side and is glued with a quarter-wave film on an end face close to the object side, and the quarter-wave film is glued with a linearly polarized film 5 on an end face away from the second lens 2; and the third lens 3 is coated with an AR film on both end faces close to the object side and the image side.

[0043] In the technical scheme provided in the present application, the light rays on the image side pass through the first lens 1, the second lens 2 and the quarter-wave film in sequence, are reflected by the linearly polarized film 5 to form reflected light; the reflected light passes through the quarter-wave film, the second lens 2 and the first lens 1 in sequence, is reflected by the half-reflective half-transmissive film on an end face of the first lens 1 close to the image side to form secondary reflected light; and the secondary reflected light passes through the first lens 1, the second lens 2, the quarter-wave film, the linearly polarized film 5 and the third lens 3 in sequence to reach the object side. In fact, in the propagation path of the light rays, the quarter-wave film added in the optical path between the lens module (i.e. the first lens 1, the second lens 2 and the third lens 3) and the linearly polarized film compensates the polarization of the polarized light transmitted between the lens module and the linearly polarized film 5, so that the polarized light incident on the linearly polarized film 5 is corresponding linearly polarized light. In this way, the depolarization of the light rays caused by the birefringence effect of the lens can be effectively compensated, the ghost can be eliminated, the light efficiency can be ensured, and thus the imaging quality can be improved and the viewing effect of the user can be improved.

[0044] Further, in the present embodiment, in order to ensure that the light rays can be smoothly transmitted in the optical system 100, the first lens 1 has a positive optical power, the second lens 2 has a negative optical power, and the third lens 3 has a positive optical power.

[0045] Furthermore, the expansion coefficient of the first lens 1 is P1, where 50 < P1 < 70. The expansion coefficient of the first lens 1 can be 50, 55, 60, 65, or 70. The expansion coefficient of the second lens 2 is P2, where 50 < P2 < 70. The expansion coefficient of the second lens 2 can be 50, 55, 60, 65, or 70. The expansion coefficient of the third lens 3 is P3, where 50 < P3 < 70. The expansion coefficient of the third lens 3 can be 50, 55, 60, 65, or 70. It should be noted that within the above expansion coefficient range, it can ensure that light is smoothly transmitted in the optical system 100, which is beneficial to eliminating ghost images and ensuring light efficiency, thereby improving the imaging quality and the user's viewing effect. As a preferred embodiment of this embodiment, the expansion coefficient P1 of the first lens 1 is 60, the expansion coefficient P2 of the second lens 2 is 60, and the expansion coefficient P3 of the third lens 3 is 60.

[0046] In addition, the materials of the first lens 1, the second lens 2, and the third lens 3 are not limited, as long as they are transparent and can transmit light. In this embodiment, at least one of the materials of the first lens 1, the second lens 2, and the third lens 3 is a plastic material. In another embodiment, at least one of the materials of the first lens 1, the second lens 2, and the third lens 3 is a glass material. Compared with the setting of the glass material, the plastic material is more preferred, as the plastic material has a longer service life, and glass is a fragile product that is prone to breakage under the action of external forces. [[ID=​​​​​​​​​Wherein, c is the curvature corresponding to the radius, y is the radial coordinate, k is the conic quadratic curve coefficient, when the k coefficient is less than-1, the surface shape curve of the lens is hyperbola, when the k coefficient is equal to-1, the surface shape curve of the lens is parabola, when the k coefficient is between-1 and 0, the surface shape curve of the lens is ellipse, when the k coefficient is equal to 0, the surface shape curve of the lens is circle, when the k coefficient is greater than 0, the surface shape curve of the lens is oblate; a1 to a8 are respectively the coefficients corresponding to each radial coordinate.

[0051] In the embodiment, taking F3.58 as an example, the actual design parameters of the VR-pancake with a focal length of 28.7mm and a FOV of 94° are shown in Table 1, for the convenience of description, the two opposite end faces of the first lens 1 are respectively the first lens S1 and the first lens S2; the two opposite end faces of the second lens 2 are respectively the second lens S1 and the second lens S2; the two opposite end faces of the third lens 3 are respectively the third lens S1 and the third lens S2.

[0052] Table 1 Design parameters

[0053]

[0054]

[0055] Further, in the embodiment, the coefficients of the third lens S2 and the third lens S1 are shown in Table 2 and Table 3.

[0056] Table 2 Coefficients of the third lens S2

[0057] Coefficient k 2.97 a1 0 a2 -1.68974E-05 a3 6.46205E-08 a4 -9.61367E-11 a5 -4.23802E-14 a6 -3.2982E-18 a7 1.85927E-21 a8 0

[0058] Table 3 Coefficients of the third lens S1

[0059] Coefficient k 20.30 a1 0 a2 -2.02966E-05 a3 2.8861E-08 a4 8.94054E-12 a5 5.71897E-15 a6 -1.16079E-16 a7 -3.39817E-19 a8 0

[0060] Further, in the embodiment, the coefficients of the second lens S2 and the second lens S1 are shown in Table 4 and Table 5.

[0061] Table 4 Coefficients of the second lens S2

[0062]

[0063]

[0064] Table 5 Coefficients of the second lens S1

[0065] Coefficient k 11.85 a1 0 a2 5.47347E-06 a3 -3.45391E-09 a4 1.14936E-12 a5 -3.38447E-15 a6 2.24154E-17 a7 -1.22243E-20 a8 0

[0066] Further, in the embodiment, the coefficients of the first lens S2 and the first lens S1 are shown in Table 4 and Table 5.

[0067] Table 4 First lens S2 coefficients

[0068]

[0069]

[0070] Table 5 First lens S1 coefficients

[0071] Coefficient k -1.13 a1 0 a2 -1.49987E-07 a3 4.65592E-11 a4 -4.063E-13 a5 -7.48582E-16 a6 -1.99338E-19 a7 1.08621E-21 a8 0

[0072] In the embodiment, the transmission path of the light is as follows:

[0073] S100, the light on the image side sequentially passes through the first lens 1, the second lens 2 and the quarter-wave film, is reflected by the linear polarizing film 5 to form reflected light;

[0074] S200, the reflected light sequentially passes through the quarter-wave film, the second lens 2 and the first lens 1, is reflected by the half-reflecting half-transmitting film on the end face of the first lens 1 close to the image side to form secondary reflected light;

[0075] S300, the secondary reflected light sequentially passes through the first lens 1, the second lens 2, the quarter-wave film, the linear polarizing film 5 and the third lens 3, and reaches the object side.

[0076] Further, the polarization state between the quarter-wave film and the image side is clockwise circular polarization 6, the polarization state between the quarter-wave film and the linear polarizing film 5 is vertical linear polarization 77; the polarization state between the linear polarizing film 5 and the first lens 1 is counterclockwise circular polarization 9; the polarization state between the first lens 1 and the quarter-wave film is counterclockwise circular polarization 9, and the polarization state between the quarter-wave film and the object side is horizontal linear polarization 88.

[0077] Specifically, in the embodiment, on the transmission path of the light on the image side sequentially passing through the first lens 1, the second lens 2 and the quarter-wave film, the polarization state between the first lens S1 and the image side is clockwise circular polarization 6, the polarization state between the first lens S2 and the second lens S1 is clockwise circular polarization 6, the polarization state between the second lens S2 and the quarter-wave film is clockwise circular polarization 6, and the polarization state between the quarter-wave film and the linear polarizing film 5 is vertical linear polarization 77.

[0078] On the transmission path of the reflected light passing through the quarter-wave film, the second lens 2 and the first lens 1 in turn, the polarization state between the quarter-wave film and the linear polarization film 5 is vertical linear polarization 77, the polarization state between the second lens S2 and the quarter-wave film is counterclockwise polarization, and the polarization state between the second lens S1 and the first lens S1 is counterclockwise polarization state.

[0079] On the transmission path of the twice-reflected light passing through the first lens 1, the second lens 2, the quarter-wave film, the linear polarization film 5 and the third lens 3 in turn to the object side, the polarization state between the first lens S1 and the second lens S1 is counterclockwise polarization, the polarization state between the second lens S2 and the quarter-wave film is counterclockwise polarization, the polarization state between the quarter-wave film and the linear polarization film 5 is horizontal polarization, the polarization state between the linear polarization film 5 and the third lens S1 is horizontal polarization, and the polarization state between the third lens S2 and the object side is horizontal polarization.

[0080] In an embodiment, the image side is a display screen, and the object side is a human eye (or pupil). It should be noted that the type of the display screen 200 is not limited in the embodiment, for example, the display screen can be any one of an LCD (Liquid Crystal Display) display screen, an OLED (Organic Light-Emitting Diode) display screen, a Micro OLED micro display screen, a Mini LED micro display screen, a DLP (Digital Light Processing) display screen, an LCOS (Liquid Crystal on Silicon) display screen and the like. In addition, the display screen can be a flexible screen or a rigid screen (i.e., a non-flexible screen). In actual application, the display screen can be selected according to user demand.

[0081] In addition, the application further provides a VR glasses comprising the optical system 100. The specific structure of the optical system 100 is referred to the above-mentioned embodiments. Since the VR glasses adopts all the technical solutions of the above-mentioned embodiments, at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here.

[0082] The above only describes the preferred embodiments of the present application, and does not limit the patent scope of the present application, any equivalent structural transformation made on the basis of the concept of the present application, or direct / indirect application in other related technical fields is included in the patent protection scope of the present application.

Claims

1. An optical system, characterized in that, It has an object side and an image side that are relatively arranged along the extending direction of the optical axis. The optical system includes a first lens, a second lens, and a third lens arranged in sequence from the image side to the object side, where: A semi-reflective and semi-transmissive film is coated on the end face of the first lens close to the image side, and an AR transmissive film is coated on the end face close to the object side; An AR anti-reflection film is coated on one end face of the second lens close to the image side, a quarter-wave plate film is glued on the end face close to the object side, and a linear polarizing film is glued on the end face of the quarter-wave plate film facing away from the second lens; AR anti-reflection films are coated on both end faces of the third lens close to the object side and the image side; The optical power of the first lens is positive; The optical power of the second lens is negative; The optical power of the third lens is positive; The radius of curvature of the object side surface of the third lens is 280.35 mm, the distance from the object side surface of the third lens to the image side surface of the third lens is 5.82 mm, the radius of curvature of the image side surface of the third lens is -101.48 mm, the distance from the image side surface of the third lens to the object side surface of the second lens is 3.16 mm, the radius of curvature of the object side surface of the second lens is -60.40 mm, the distance from the object side surface of the second lens to the image side surface of the second lens is 2.84 mm, the radius of curvature of the image side surface of the second lens is -95.26 mm, the distance from the image side surface of the second lens to the object side surface of the first lens is 3.16 mm, the radius of curvature of the object side surface of the first lens is -85.49 mm, the distance from the object side surface of the first lens to the image side surface of the first lens is 8.19 mm, and the radius of curvature of the image side surface of the first lens is -50.74 mm.

2. The optical system as described in claim 1, characterized in that, The expansion coefficient of the first lens is P1, where 50 < P1 < 70; and / or, The expansion coefficient of the second lens is P2, where 50 < P2 < 70; and / or, The expansion coefficient of the third lens is P3, where 50 < P3 < 70.

3. The optical system as described in claim 1, characterized in that, The first lens, the second lens, and the third lens are all aspherical mirrors; and / or, The material of at least one of the first lens, the second lens, and the third lens is a plastic material.

4. The optical system as described in claim 3, characterized in that, The surface shape of the aspherical surface of any one of the first lens, the second lens, and the third lens satisfies Formula I, and Formula I is ； Where, c is the curvature corresponding to the radius, y is the radial coordinate, whose unit is the same as the lens length unit, k is the conic quadratic curve coefficient, and a1 to a8 are the coefficients corresponding to each radial coordinate.

5. The optical system as claimed in claim 1, characterized in that, The light rays on the image side sequentially pass through the first lens, the second lens, and the quarter-wave plate film, and are reflected by the linear polarizing film to form reflected light; The reflected light sequentially passes through the quarter-wave plate film, the second lens, and the first lens, and is reflected by the semi-reflective and semi-transmissive film on the end face of the first lens close to the image side to form secondary reflected light; The secondary reflected light sequentially passes through the first lens, the second lens, the quarter-wave plate film, the linear polarizing film, and the third lens, and reaches the object side.

6. The optical system as claimed in claim 5, characterized in that, The polarization state between the quarter-wave plate film and the image side is clockwise circular polarization, and the polarization state between the quarter-wave plate film and the linearly polarized film is vertical linear polarization.

7. The optical system as claimed in claim 5, characterized in that, The polarization state between the linearly polarizing film and the first lens is counterclockwise circular polarization.

8. The optical system as claimed in claim 5, characterized in that, The polarization state between the first lens and the quarter-wave plate film is counterclockwise circular polarization, and the polarization state between the quarter-wave plate film and the object side is horizontal linear polarization.

9. A VR headset, characterized in that, Includes the optical system as described in any one of claims 1 to 8.

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