A micro lens for a VR device

Abstract

The application relates to the technical field of lenses and discloses a micro lens for a VR device, which is different from traditional processes and does not need a lens barrel for assembly, and the alignment bonding is completed by high-precision equipment, so that the problems of alignment eccentricity and oversize of a traditional lens are improved, the micro lens sequentially comprises a lens unit, lens protection glass, chip protection glass and an image plane in a direction from an object side to an image side along an optical axis, the lens unit sequentially comprises a first lens, a second lens, a third lens and a fourth lens in the direction from the object side to the image side, the lens features are a plano-convex lens or a plano-concave lens, the lens layers are fixed together by UV glue bonding, and a total of three layers of bonding is adopted; the aspheric surface type is formed by stamping with a metal mold, and the material is stamping glue. The application is favorable for reducing cost, improving yield, providing a basis for batch production of micro lenses and having great application space in modern optical processing in the future.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lenses, in particular to a micro lens for a VR device. BACKGROUND

[0002] The advent of 5G is an unstoppable trend. From 2G to 4G era, human interaction media based on mobile terminals has experienced the evolution of text, language, picture and video. In the 5G era, VR development has shown a breakthrough direction.

[0003] In fact, the macro policy support and the entry of some large factories in China determine the macro resource inflow into the VR field, which determines the development trend in recent years. In the long run, the VR product will be updated and iterated, and the product weight will be lighter and lighter. The extremely lightweight device will also create conditions for high-frequency daily use, combined with the maturity of some motion sensing devices to bring people new interactive experiences, thus creating opportunities for new national applications.

[0004] For VR, the extremely lightweight device will have requirements for the weight and size of the lens. The advantage of modern optical processing WLO is to make excellent miniature imaging lenses. The so-called WLO wafer-level optical device is a wafer-level optical manufacturing technology. Unlike traditional optical processing technology, WLO technology uses semiconductor processing to mass-produce lenses on a whole glass wafer. Multiple lens wafers are bonded together and then cut into single lenses, with the characteristics of small size and good consistency. SUMMARY

[0005] In order to overcome the defects of the prior art, the purpose of the present application is to provide a micro lens for a VR device to solve the technical problems of alignment eccentricity and oversize of the micro lens in the prior art.

[0006] The present application is realized by the following technical solutions:

[0007] A micro lens for a VR device, the side close to the eye when worn is the object side, and the side away from the eye is the image side. The lens unit, lens protection glass, chip protection glass and image surface are sequentially arranged along the optical axis from the object side to the image side. The lens unit sequentially includes a first lens, a second lens, a third lens and a fourth lens from the object side to the image side. The surface shape of the first lens, the second lens, the third lens and the fourth lens is aspherical. The first lens has a negative refractive power and the object side is a plane, and the image side is a concave surface. The second lens has a positive refractive power and the object side is a convex surface, and the image side is a plane. The third lens has a positive refractive power and the object side is a plane, and the image side is a convex surface. The fourth lens has a positive refractive power and the object side is a plane, and the image side is a convex surface.

[0008] Preferably, the first lens is assembled on one side of the first glass substrate close to the object side, the second lens is assembled on one side of the second glass substrate close to the image side, and the third lens is assembled on the other side of the second glass substrate close to the object side; and the fourth lens is assembled on the third glass substrate close to the object side.

[0009] Further, the side of the first lens close to the image side is fixedly arranged with the side of the second lens close to the object side by the first glue; the side of the third lens close to the image side is fixedly arranged with the third glass substrate by the second glue; and the side of the fourth lens close to the image side is fixedly arranged with the lens protection glass by the third glue.

[0010] Still further, the side of the third glass substrate close to the object side is a first plane, the side of the lens protection glass close to the object side is a second plane, the side of the first lens close to the image side is a first even aspheric surface, the side of the second lens close to the object side is a second even aspheric surface, the side of the third lens close to the image side is a third even aspheric surface, and the side of the fourth lens close to the image side is a non-spherical surface.

[0011] Further, a diaphragm is arranged between the side of the third lens close to the object side and the second glass substrate.

[0012] Further, the side of the first glass substrate close to the object side is coated with an AR film layer.

[0013] Further, the thickness of the first glass substrate, the second glass substrate and the third glass substrate ranges from 0.21 to 0.55 mm.

[0014] Preferably, the depth-to-width ratio of the aspheric surface height and the aspheric surface aperture of the first lens, the second lens, the third lens and the fourth lens satisfies the depth-to-width ratio condition, which is as follows:

[0015] Q is less than 0.35;

[0016] wherein Q is the depth-to-width ratio, h is the depth or height of the aspheric surface, and D is the aspheric surface aperture.

[0017] Preferably, the surface type of the first lens, the second lens, the third lens and the fourth lens is a stamping glue material, the refractive index of the stamping glue material is inversely proportional to the Abbe number, that is, the greater the refractive index, the smaller the Abbe number, and the characteristic conditions of the refractive index Nd and the Abbe number Vd of the stamping glue are as follows:

[0018] 1.45≤Nd≤1.75, 24≤Vd≤60.

[0019] Preferably, the calculation equation of the aspheric surface type of the first lens, the second lens, the third lens and the fourth lens is as follows:

[0020]

[0021] Wherein, C is curvature, h is the whole thickness of the lens, K is conic coefficient, A4, A6, A8, A 10 Respectively, the non-spherical high-order term coefficient of four, six, eight, ten.

[0022] Compared with the prior art, the present application has the following beneficial technical effects:

[0023] The application provides a micro lens for a VR device, which is different from traditional processes, and does not require a lens barrel for assembly, and alignment bonding is completed by high-precision equipment, thereby improving the problems of alignment eccentricity and oversize of traditional lenses, and the micro lens comprises, in sequence from the object side to the image side along the optical axis, a lens unit, a lens protection glass, a chip protection glass and an image surface, wherein the lens unit comprises, in sequence from the object side to the image side, a first lens, a second lens, a third lens and a fourth lens; the lens features are a flat convex lens or a flat concave lens, and the lens layers are fixed together by UV glue bonding, and a total of three layers of bonding; the aspheric surface type is formed by stamping with a metal mold, and the material is stamping glue. The application is beneficial to reduce cost, improve yield, and provide a basis for mass production of micro lenses, and has great application space in modern optical processing in the future.

[0024] Further, the base thickness ranges of the first glass substrate, the second glass substrate and the third glass substrate are set to ensure that their warping is within a controllable range.

[0025] Further, the aspheric surface height and aspheric surface aperture of the first lens, the second lens, the third lens and the fourth lens meet the aspect ratio condition, and the surface type is sequentially limited, so that the aspheric surface type gradually changes a little slower, which can better reduce the mold processing difficulty and the uncontrollable phenomenon in stamping. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The software simulation light path diagram of the micro lens in the application;

[0027] Figure 2 The structural schematic diagram of the micro lens in the application;

[0028] Figure 3 The Spot point column diagram of the application in the 800-900nm waveband;

[0029] Figure 4 The diffraction MTF of the application in the 800-900nm waveband;

[0030] Figure 5 The MTF@ field of view of the application in the 800-900nm waveband;

[0031] Figure 6 This invention addresses grid distortion in the 800-900nm wavelength band.

[0032] Figure 7 This is a relative illumination diagram of the present invention in the 800-900nm wavelength band;

[0033] Figure 8 This is the field curvature and distortion diagram of the present invention in the 800-900nm band;

[0034] Figure 9 This is the HA Mark diagram of the present invention;

[0035] Figure 10 This is the photolithographic aperture pattern of the present invention.

[0036] In the diagram: 101-First glass substrate; 102-First lens; 103-First adhesive; 104-Second lens; 105-Second glass substrate; 106-Third lens; 107-Second adhesive; 108-Third glass substrate; 109-Fourth lens; 110-Third adhesive; 111-Lens protective glass; 112-HA adhesive layer; 113-Chip protective glass; 201-AR film layer; 202-First even-order aspherical surface; 203-Second even-order aspherical surface; 204-Aperture stop; 205-Third even-order aspherical surface; 206-First plane; 207-Aspherical surface; 208-Second plane; 209-Image plane. Detailed Implementation

[0037] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0038] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0039] The present invention will now be described in further detail with reference to the accompanying drawings:

[0040] The purpose of this invention is to provide a miniature lens for VR devices, so as to solve the technical problems of misalignment and excessive size of miniature lenses in the prior art.

[0041] Specifically, according to Figure 1 and Figure 2 As shown, the miniature lens has the side closer to the human eye when worn as the object side and the side farther from the human eye as the image side. Along the optical axis from the object side to the image side, it sequentially includes a lens unit, a lens protective glass 111, a chip protective glass 113, and an image plane 209. The lens unit, from the object side to the image side, sequentially includes a first lens 102, a second lens 104, a third lens 106, and a fourth lens 109. The surfaces of the first lens 102, second lens 104, third lens 106, and fourth lens 109 are all aspherical. Specifically, the first lens 102 has negative refractive power and its object side is flat, while its image side is concave; the second lens 104 has positive refractive power and its object side is convex, while its image side is flat; the third lens 106 has positive refractive power and its object side is flat, while its image side is convex; and the fourth lens 109 has positive refractive power and its object side is flat, while its image side is convex.

[0042] Specifically, the first lens 102 is mounted on the first glass substrate 101 on the side closest to the object surface, the second lens 104 is mounted on one side of the second glass substrate 105 on the side closest to the image surface, the third lens 106 is mounted on the other side of the second glass substrate 105 on the side closest to the object surface, and the fourth lens 109 is mounted on the third glass substrate 108 on the side closest to the object surface.

[0043] The first lens 102 is bonded and fixed to the image side of the first lens 102 and the object side of the second lens 104 by the first adhesive 103; the third lens 106 is bonded and fixed to the third glass substrate 108 by the second adhesive 107; and the fourth lens 109 is bonded and fixed to the lens protective glass 111 by the third adhesive 110.

[0044] Among them, the side of the third glass substrate 108 closest to the object side is the first plane 206, the side of the lens protective glass 111 closest to the object side is the second plane 208, the side of the first lens 102 closest to the image side is the first even-order aspherical surface 202, the side of the second lens 104 closest to the object side is the second even-order aspherical surface 203, the side of the third lens 106 closest to the image side is the third even-order aspherical surface 205, and the side of the fourth lens 109 closest to the image side is an aspherical surface 207.

[0045] An aperture 204 is provided between the side of the third lens 106 closest to the object and the second glass substrate 105.

[0046] The first glass substrate 101 has an AR film layer 201 deposited on the side closest to the object.

[0047] The thickness of the first glass substrate 101, the second glass substrate 105, and the third glass substrate 108 ranges from 0.21 < d < 0.55 mm.

[0048] Specifically, the aspherical sag and aspherical aperture of the first lens 102, the second lens 104, the third lens 106, and the fourth lens 109 satisfy the aspect ratio condition, which is as follows:

[0049] Q is less than 0.35;

[0050] Where Q is the aspect ratio, h is the depth or height of the aspherical surface, and D is the aspherical aperture.

[0051] Specifically, the surface profiles of the first lens 102, the second lens 104, the third lens 106, and the fourth lens 109 are all made of embossed adhesive. The refractive index of the embossed adhesive is inversely proportional to the Abbe number; that is, the higher the refractive index, the lower the Abbe number. The characteristic conditions of the refractive index Nd and the Abbe number Vd of the embossed adhesive are as follows:

[0052] 1.45≤Nd≤1.75、24≤Vd≤60、

[0053] Specifically, the calculation equations for the aspherical surface shapes of the first lens 102, the second lens 104, the third lens 106, and the fourth lens 109 are as follows:

[0054]

[0055] Where C is the curvature, h is the overall thickness of the lens, K is the conic coefficient, and A4, A6, A8, A 10 The coefficients of the aspherical higher-order terms are 4, 6, 8, and 10, respectively.

[0056] This invention relates to a miniature imaging lens for the 800-900nm wavelength band, with an object distance of 10-25mm, a field of view of 90.6°, and an f / 2.8 aperture. The overall lens dimensions are 1.4*1.4*2.85mm, comprising four aspherical surfaces, effectively compressing the lens length. The diffraction MTF is greater than 0.35 at 114 lp / mm, resulting in clear imaging. Distortion is -3.9%, ensuring that excessive distortion does not negatively impact visual quality. The MTF@field-of-view curve is smooth, indicating a clear difference in aberrations between the center and edge of the field of view, resulting in good image quality.

[0057] In this invention, the thickness of the chip protective glass also participates in imaging. Therefore, the thickness of the chip protective glass and the air gap between the chip protective glass and the photosensitive area are added in front of the image in the optical design software.

[0058] according to Figure 1 and Figure 2 As shown, there are four lenses: the first lens 102, the second lens 104, the third lens 106, and the fourth lens 109, all of which are aspherical. There are three air gaps, requiring three bonding layers. The substrate glass is D263T material with thicknesses of 0.3 mm and 0.45 mm, respectively.

[0059] On the side closest to the image plane, 111 serves as the lens protective glass, 113 as the chip protective glass, and 211 as the image plane. The entire optical system is bounded by and includes the lens protective glass 111, with the aperture stop 204 located between the second glass substrate 105 and the third lens 106.

[0060] The surface parameters of each lens are shown in Table 1:

[0061] Surf h Radius Thickness Glass Semi-Diameter(D / 2) OBJ Infinity 15 / 15.744 1 Infinity 0.3 D263TECO 0.705 2 Infinity 0.03 Nd:1.56,Vd:52 0.545 3 0.216 0.32 0.3 / 0.414 4 0.038 0.8072 0.125 Nd:1.75,Vd:31 0.345 5 Infinity 0.45 D263TECO 0.322 STP Infinity 0.115 Nd:1.75,Vd:31 0.182 7 0.037 -0.8371 0.175 / 0.211 8 Infinity 0.3 D263TECO 0.278 9 Infinity 0.08 Nd:1.56,Vd:52 0.345 10 0.026 -1.0784 0.12 / 0.357 11 Infinity 0.45 D263TECO 0.411 12 Infinity 0.01 Nd:1.51,Vd:54 0.519 13 Infinity 0.4 D263TECO 0.521 14 Infinity 0.045 / 0.627 IMA Infinity / / 0.645

[0062] Table 1: Lens Parameters

[0063] The coefficients of higher-order terms for aspherical surfaces are shown in Table 2.

[0064] Surf Conic A4 A6 A8 A10 3 -0.8764 -0.3381 -2.6761E+001 -8.5462E+003 3.4865E+004 4 -1.3875 -0.5423 -0.9154 4.6254E+002 6.5451E+003 7 2.9748 -0.3561 6.4506 3.6548E+003 1.3517E+005 10 2.2937 0.4629 -1.6945E+001 -1.1456+002 2.6384E+003

[0065] Table 2: Coefficients of Higher-Order Terms for Aspherical Surfaces

[0066] As shown in Table 1 above, the aspect ratios of the first lens 102 are Q1 = 0.216 / (2*0.414) = 0.261, the second lens 104 are Q2 = 0.038 / (2*0.345) = 0.055, the third lens 106 are Q3 = 0.037 / (2*0.211) = 0.088, and the fourth lens 109 are Q4 = 0.026 / (2*0.357) = 0.036. All of these satisfy the aspect ratio condition, that is, Q is less than 0.35.

[0067] The glass substrates used have corresponding thicknesses of 0.3mm and 0.45mm, which both meet the thickness range of the first glass substrate 101, the second glass substrate 105 and the third glass substrate 108, i.e. 0.21 < d < 0.55mm.

[0068] The characteristic parameters of the UV adhesive material used in the lens all meet the characteristic conditions of the refractive index Nd and Abbe number Vd of the imprinting adhesive, namely 1.45≤Nd≤1.75 and 24≤Vd≤60.

[0069] In this invention example, the dot plot of the lens in the 800-900nm wavelength band is as follows:Figure 3 As can be seen from the figure, the diffuse spot lies within the Airy disk, indicating that the geometric aberration is less than the aberration produced by diffraction; Figure 4 The diffraction MTF shows that at a spatial frequency of 114 lp / mm, the MTF is greater than 0.3, indicating excellent imaging results. Looking at the MTF@field of view, as... Figure 5 At on-axis points, the MTF is greater than 0.65 at 114 lp / mm and greater than 0.83 at 57 lp / mm. The overall lines are relatively smooth, meaning there is no significant difference in aberration between the center and edges of the field of view; lens distortion in this band is as follows... Figure 6 The distortion is -0.391%, which is very small, ensuring image quality and preventing excessive distortion from affecting the viewing experience. The lens's illuminance curve is as follows: Figure 7 It can be seen that the relative illumination is >52%; the field curvature of the lens is as follows: Figure 8 The field curvature is less than 0.04mm, meaning that the overall sharpness of the central and edge fields of view is consistent.

[0070] In this invention, the miniature lens is coated with an AR film layer 201, specifically, the first even-order aspherical surface 202, the second even-order aspherical surface 203, the third even-order aspherical surface 205, the first plane 206, the aspherical surface 207, and the second plane 208 are all coated with anti-reflection films. A long-pass IR film is coated on one side of the lens protective glass 111, and an HA adhesive layer 112 is coated between the lens protective glass 111 and the chip protective glass 113.

[0071] The aperture 204 of this invention is fabricated using photolithography. Figure 10 Similarly, a photolithographic Mark200 is also made on the AR film layer 201. Figure 9

[0072] After the optical design simulation is completed, this invention needs to... Figure 1 Make some structural changes, such as Figure 2 As shown. First, the glass aperture needs to be uniformly extended to the size of the chip protective glass, making the overall structure a rectangle. This is necessary to allow for bonding width and to determine the aperture for easy cutting. The extension is made outside the effective area of ​​the aspherical surface, such as... Figure 2 As shown on the right, the extended curve should smoothly connect with the aspherical curve without affecting the surface shape of the aspherical region, avoiding sharp edges that could affect the mold machining accuracy. During the extension process, it is important to ensure the bonding width, and the bonding must occur between planes.

[0073] As Figure 2The image shown is a cross-sectional view of the product corresponding to an embodiment of the present invention. The first lens 102 has negative refractive power, the second lens 104 has positive refractive power, the third lens 106 has positive refractive power, and the fourth lens 109 has positive refractive power. The glass substrate material is Schott D263TECO. The first glass substrate 101 of the first lens 102 is 0.3 mm thick, the second glass substrate 105 of the second lens 104 and the third lens 106 is 0.45 mm thick, and the third glass substrate 108 of the fourth lens 109 is 0.3 mm thick. The lens bonding layers are 103, 107, and 110, and further to the right are the lens protective glass 111, the HA adhesive layer 112, and the chip protective glass 113. The adhesive layer thickness is 30 ± 5 μm, and the width is 150 μm.

[0074] In summary, this invention provides a miniature lens for VR devices. Unlike traditional processes, its assembly does not require a lens barrel; alignment and bonding are assisted by high-precision equipment, thus improving the problems of alignment misalignment and excessive size in traditional lenses. The lens comprises, along the optical axis from the object side to the image side, a lens unit, a lens protective glass, a chip protective glass, and an image plane. The lens unit, from the object side to the image side, includes a first lens, a second lens, a third lens, and a fourth lens. The lens features are either plano-convex or plano-concave, and the lens layers are bonded together with UV adhesive, totaling three layers. The aspherical surface is formed by metal mold pressing using imprinting adhesive. This invention helps reduce costs, improve yield, and provides a foundation for the mass production of miniature lenses, with significant potential for future applications in modern optical processing.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A miniature lens for VR devices, wherein the side closer to the human eye when worn is the object side, and the side farther from the human eye is the image side, characterized in that, Along the optical axis from the object side to the image side, the lens unit comprises a lens unit, a lens protective glass (111), a chip protective glass (113), and an image plane (209). The lens unit is composed of a first lens (102), a second lens (104), a third lens (106), and a fourth lens (109) from the object side to the image side. The surface of the first lens (102), the second lens (104), the third lens (106), and the fourth lens (109) are all aspherical. Among them, the first lens (102) has negative refractive power and the object side is flat, while the image side is concave. The second lens (104) has positive refractive power and the object side is convex, while the image side is flat. The third lens (106) has positive refractive power and the object side is flat, while the image side is convex. The fourth lens (109) has positive refractive power and the object side is flat, while the image side is convex. The first lens (102) is mounted on the first glass substrate (101) on the side closest to the object, the second lens (104) is mounted on one side of the second glass substrate (105) on the side closest to the image, the third lens (106) is mounted on the other side of the second glass substrate (105) on the side closest to the object, and the fourth lens (109) is mounted on the third glass substrate (108) on the side closest to the object. The first lens (102) is bonded and fixed to the image side of the second lens (104) and the object side of the second lens (104) by the first adhesive (103); the third lens (106) is bonded and fixed to the third glass substrate (108) by the second adhesive (107); the fourth lens (109) is bonded and fixed to the lens protective glass (111) by the third adhesive (110) on the image side. The third glass substrate (108) has a first plane (206) on the side closest to the object side, the lens protective glass (111) has a second plane (208) on the side closest to the object side, the first lens (102) has a first even-order aspherical surface (202) on the side closest to the image side, the second lens (104) has a second even-order aspherical surface (203) on the side closest to the object side, the third lens (106) has a third even-order aspherical surface (205) on the side closest to the image side, and the fourth lens (109) has an aspherical surface (207) on the side closest to the image side. The aspherical sag and aspherical aperture of the first lens (102), the second lens (104), the third lens (106), and the fourth lens (109) satisfy the aspect ratio condition, which is as follows: Q is less than 0.35; Where Q is the aspect ratio, H is the aspherical sag, and D is the aspherical aperture.

2. A miniature lens for a VR device according to claim 1, characterized in that, An aperture stop (204) is provided between the side of the third lens (106) near the object and the second glass substrate (105).

3. A miniature lens for a VR device according to claim 1, characterized in that, The first glass substrate (101) has an AR film layer (201) on the side closest to the object side.

4. A miniature lens for a VR device according to claim 1, characterized in that, The thickness of the first glass substrate (101), the second glass substrate (105) and the third glass substrate (108) ranges from 0.21 < d < 0.55 mm.

5. A miniature lens for a VR device according to claim 1, characterized in that, The surface profiles of the first lens (102), the second lens (104), the third lens (106), and the fourth lens (109) are all made of embossed adhesive. The refractive index of the embossed adhesive is inversely proportional to the Abbe number, that is, the larger the refractive index, the smaller the Abbe number. The characteristic conditions of the refractive index Nd and the Abbe number Vd of the embossed adhesive are as follows: 1.45≤Nd≤1.75、24≤Vd≤60、 6. A miniature lens for a VR device according to claim 1, characterized in that, The equations for calculating the aspherical surface profiles of the first lens (102), the second lens (104), the third lens (106), and the fourth lens (109) are as follows: ； Where C is the curvature, h is the radial distance from any point on the surface to the optical axis, K is the conic coefficient, and A4, A6, and A8 are the coefficients of the four, six, and eight higher-order aspheric terms, respectively.

Images