TW201344278A - Micro-lens module - Google Patents

Abstract

A micro-lens module including a first lens group and a second lens group is provided. The first lens group disposed between an object side and an image side has a first aspheric surface which is the surface closest to the object side and a second aspheric surface which is the surface closest to the image side. The second lens group disposed between the first lens group and the image side has a third aspheric surface which is the surface closest to the first lens group and a fourth aspheric surface which is the surface closest to the image side. An overall length of the micro-lens module is L, an effective focal length (EFL) of the micro-lens module is f, and an EFL of the second lens group is f2. The micro-lens module satisfies following conditions: 1.5 > L/f > 0.6, and -7 > f2/f > -14.

Description

Micro lens module

The present invention relates to a lens module, and more particularly to a microlens module.

With the advancement of technology, various portable electronic products such as mobile phones and personal digital assistants (PDAs), notebook computers (notebook PCs), tablet PCs, etc. are usually equipped with miniature camera lenses. Allow users to record the glimpses of life. Camera performance has become a common and basic feature of portable electronics as performance continues to increase and prices continue to fall.

In general, miniature lenses for photography need to provide ideal imaging quality and miniaturized dimensions to meet market demands. At present, the miniature lens modules on the market have different structures according to the requirements of different pixel numbers. For example, current miniature lens modules typically include 1 to 5 optical components and have different structural designs. On the other hand, the difference in the lens manufacturing method also makes the structural design different. According to current manufacturing methods, the types of lenses are generally classified into plastic-emitting aspherical lenses, glass spherical lenses, aspherical glass lenses, and composite lenses. The miniature lens module has the aforementioned classified lens, and is based on different optical component structure designs, and generally includes an independent aperture and an IR-CUT film. Independent apertures are also used to eliminate stray light generated by the various optical components. However, in the current application of more than one megapixels with ideal imaging quality and miniaturized size, better micro lens modules with complex optical components are still seeking further development.

The present invention is directed to a miniature lens module that provides ideal image quality and miniaturized dimensions.

An exemplary embodiment of the present invention provides a miniature lens module including a first lens group and a second lens group. The first lens group disposed between the object side and the image side has a first aspheric surface which is the surface closest to the object side, and a second aspheric surface which is the surface closest to the image side. The second lens group disposed between the first lens group and the image side has a third aspheric surface which is closest to the surface of the first lens group, and a fourth aspheric surface which is the surface closest to the image side. The total length of the micro lens module is L, the effective focal length (EFL) of the micro lens module is f, and the effective focal length of the second lens group is f2. The miniature lens module satisfies the following conditions: 1.5>L/f>0.6, and -7>f2/f>-14.

In an exemplary embodiment of the present invention, the distance between the first aspheric surface and the second aspheric surface is L1, and the distance between the third aspheric surface and the fourth aspheric surface is L2. The miniature lens module satisfies 1.3>L1/L2>0.8.

In an exemplary embodiment of the invention, the image processing device is disposed on the image side. The distance between the second aspheric surface and the third aspheric surface is T1, and the distance between the fourth aspheric surface and one surface of the image processing apparatus is BFL. The miniature lens module satisfies 0.7>T1/BFL>0.4.

In an exemplary embodiment of the present invention, the radius of curvature of the first aspherical surface is r1, the radius of curvature of the second aspherical surface is r2, the radius of curvature of the third aspherical surface is r3, and the radius of curvature of the fourth aspherical surface is r4. The miniature lens module satisfies the following conditions: r1>0, r2>0, r3>0, and r4>0.

In an exemplary embodiment of the present invention, the first lens group includes a first lens and a second lens sequentially arranged from the object side to the image side. The first lens is a lens closest to the object side of the first lens group, and a surface facing the object side of the first lens is a first aspheric surface. The second lens is a lens closest to the second lens group among the first lens groups, and a surface of the second lens facing the image side is a second aspheric surface.

In an exemplary embodiment of the invention, the refractive indices of the first lens and the second lens are n1 and n2, respectively. The first lens satisfies 1.61>n1>1.56, and the second lens satisfies 1.55>n2>1.5.

In an exemplary embodiment of the present invention, the first lens group further includes a first light transmissive plate, an aperture diaphragm, and an infrared filter. The aperture stop is disposed on a surface of the first transparent plate facing the object side, and the infrared filter layer is disposed on a surface of the first transparent plate.

In an exemplary embodiment of the present invention, the first lens includes an integrally formed lens portion and a bearing portion, wherein the surface of the first lens bearing portion facing the object side is a matte surface.

In an exemplary embodiment of the present invention, the second lens includes an integrally formed lens portion and a bearing portion, wherein the surface of the second lens bearing portion facing the image side is a matte surface.

In an exemplary embodiment of the present invention, the second lens group includes a third lens and a fourth lens sequentially arranged from the first lens group to the image side. The third lens is a lens closest to the first lens group of the second lens group, and a surface of the third lens facing the first lens group is a third aspheric surface. The fourth lens is the lens closest to the image side of the second lens group, and the surface of the fourth lens facing the image side is a fourth aspherical surface.

In an exemplary embodiment of the invention, the refractive indices of the third lens and the fourth lens are n3 and n4, respectively. The third lens satisfies 1.55>n3>1.5, and the fourth lens satisfies 1.61>n4>1.56.

In an exemplary embodiment of the present invention, the second lens group further includes a second light transmissive plate.

In an exemplary embodiment of the invention, the third lens includes an integrally formed lens portion and a carrier portion. The surface of the carrying portion of the third lens facing the object side is a matte surface.

In an exemplary embodiment of the invention, the fourth lens includes an integrally formed lens portion and a carrier portion. The surface of the carrying portion of the fourth lens facing the image side is a matte surface.

Based on the above, according to an exemplary embodiment of the present invention, the first lens group including the aperture diaphragm and the infrared filter layer may be selectively disposed on the surface of the light transmissive plate to form a composite optical element. Therefore, a miniature lens module having a desired imaging quality including a composite optical element can be miniaturized. In addition, the lenses in the micro lens module each have a lens portion and a bearing portion, and the surface of the bearing portion is designed to be a matte surface to reduce stray light.

The above described features and advantages of the present invention will be more apparent from the following description.

FIG. 1A is a schematic structural view of a micro lens module according to an embodiment of the invention. Referring to FIG. 1A, in the embodiment, the micro lens module 100 is adapted to an image processing device 140, and includes a first lens group 110 and a second lens group 120 disposed on an optical axis A. The first lens group 110 is disposed between an object side and an image side. One surface S1 closest to the object side in the first lens group 110 is a first aspheric surface, and a surface S4 closest to the image side in the first lens group is a second aspheric surface. The second lens group 120 is disposed between the first lens group 110 and the image side. The surface S5 closest to the first lens group 110 in the second lens group 120 is a third aspherical surface, and the surface S8 closest to the image side in the first lens group is a fourth aspheric surface. The total length of the micro lens module is L, the effective focal length (EFL) of the micro lens module is f, and the effective focal length of the second lens group is f2. In order to ensure optical imaging quality, the miniature lens module satisfies the following conditions: 1.5>L/f>0.6, and -7>f2/f>-14.

In addition, in the present embodiment, the distance between the first aspheric surface S1 and the second aspheric surface S4 is L1, and the distance between the third aspheric surface S5 and the fourth aspheric surface S8 is L2. The distance between the second aspheric surface S4 and the third aspheric surface S5 is T1, and the distance between the fourth aspheric surface S8 and one surface S11 of the image processing device 140 is BFL. In this embodiment, the image processing device 140 is disposed on the image side, and the image processing device 140 includes a charge couple device (CCD) or a complementary metal-oxide-semiconductor (CMOS). Sensors, etc. Therefore, the image processing apparatus can also be used for image sensing. In order to improve the image quality, the miniature lens module satisfies the following two conditions: 1.3>L1/L2>0.8, and 0.7>T1/BFL>0.4.

In addition, in this embodiment, the radius of curvature r1 of the first aspherical surface, the radius of curvature r2 of the second aspherical surface, the radius of curvature r3 of the third aspherical surface, and the radius of curvature r4 of the fourth aspherical surface satisfy the following condition: r1>0 , r2>0, r3>0 and r4>0.

Referring again to FIG. 1A, the first lens group 110 and the second lens group 120 respectively include a plurality of lenses. In detail, the first lens group 110 disposed between the object side and the image side includes the first lens 112, the first light transmitting plate 114, and the second lens 116. The first lens 112, the first light transmissive plate 114, and the second lens 116 are sequentially arranged from the object side to the image side. The first lens 112 is closest to the object side in the first lens group 110, and the surface of the first lens 112 facing the object side is the first aspheric surface S1. On the other hand, the second lens 116 is closest to the image side in the first lens group 110, and the surface of the second lens 116 toward the image side is the second aspheric surface S4. The first light transmitting plate 114 is disposed between the first lens 112 and the second lens 116. Therefore, one surface S2 of the first lens 112 faces the image side and bears against the plane of the first light transmissive plate 114, and one surface S3 of the second lens 116 faces the object side and bears against the other one of the first light transmissive plates 114. A pair of side planes. For the first lens 112 and the second lens 116, according to an exemplary embodiment, the refractive indices of the two are n1 and n2, respectively. In this micro lens module, the first lens 112 satisfies 1.61>n1>1.56, and the second lens 116 satisfies 1.55>n2>1.5.

FIG. 1B is a schematic structural view of the first lens group in FIG. 1A. Referring to FIG. 1B , the first lens group 110 further includes an aperture stop 111 and an infrared filter layer 113 . The aperture stop 111 and the infrared filter 113 are selectively disposed on a plane of the first transparent plate 114. The aperture stop 111 is used to control the amount of light incident on the image processing device, and the infrared filter layer 113 is here used to filter out excess infrared rays. The aperture stop 111 and the infrared filter layer 113 can be formed on the surface of the lens or on the first transparent plate by a plating method. In the present exemplary embodiment, the aperture stop 111 is disposed on a plane of the first transparent plate 114 facing the surface S2. The infrared filter layer 113 is selectively disposed on at least one plane of the first light transmissive plate. Here, the infrared filter layer 113 disposed on the plane of the first light-transmissive flat plate 114 facing the surface S3 is used for illustration. Therefore, the first lens group 110 is a miniaturized composite lens element. In another embodiment, the infrared filter layer 113 may also be disposed on a plane of the first light transmissive plate 114 facing the surface S2.

On the other hand, as shown in FIG. 1A, a second lens group 120 including a third lens 122, a second light transmissive plate 124, and a fourth lens 126 is disposed between the first lens group 110 and the image side. The third lens 122, the second light transmitting plate 124, and the fourth lens 126 are sequentially arranged from one side to the image side of the first lens group 110. The third lens 122 is closest to the object side in the second lens group 120, and the surface of the third lens 122 facing the object side is the third aspheric surface S5. The fourth lens 126 is closest to the image side in the second lens group 120, and the surface of the fourth lens 122 facing the image side is the fourth aspheric surface S8. In addition, the second light transmitting plate 124 is disposed between the third lens 122 and the fourth lens 126. Therefore, one surface S6 of the third lens 122 faces the image side and bears against one plane of the second light transmitting plate 124, and one surface S7 of the fourth lens 126 faces the object side and bears against the second light transmitting plate 124. The other pair of side planes, for the third lens 122 and the fourth lens 126, according to an exemplary embodiment, have refractive indices n3 and n4, respectively. In the micro lens module, the third lens 122 satisfies 1.55>n3>1.5, and the fourth lens 126 satisfies 1.61>n4>1.56.

In addition, another aperture diaphragm (not shown) may be selectively disposed in the second lens group 120 for further controlling the amount of passing light. Referring to FIG. 1A, although the second light transmissive plate 124 and the fourth lens 126 are separately manufactured, the two may form a single lens instead of the separately manufactured second light transmissive plate 124 and fourth lens 126, thereby reducing the micro The number of lenses used by the lens module 100.

In the exemplary embodiment, the micro lens module 100 further includes a protective cover 130 disposed between the second lens group 120 and the image processing device 140 for protecting the image processing device 140. The protective cover 130 has two surfaces, one surface S9 facing the object side and the other surface S10 facing the image side and the surface S11 of the image processing device 140. In the embodiment, the material of the protective cover 130 is a transparent material such as glass or transparent resin.

One embodiment of the micro lens module 100 is as follows. It is to be noted that the data set forth in Tables 1 and 2 are not intended to limit the invention, and those skilled in the art can appropriately change the parameters or settings therein without departing from the scope of the invention.

In Table 1, the distance is the linear distance of two adjacent surfaces along the optical axis A. For example, the distance of the surface S3 is the linear distance between the surface S3 and the surface S4 along the optical axis A. For the distance, refractive index, and Abbe number of each optical element in the remark column, refer to the values corresponding to the pitch, refractive index, and Abbe number in the same column. In addition, in Table 1, the surfaces S1, S2 are the two surfaces of the first lens 112, the surfaces S3, S4 are the two surfaces of the second lens 116, and the surfaces S5, S6 are the two surfaces of the third lens 122, and the surfaces S7, S8 It is the two surfaces of the fourth lens 126, and the surfaces S9, S10 are the two surfaces of the protective cover 130, and the surface S11 is a surface of the image processing device 140, wherein the spacing in the row of the surface S10 is the surface S10 The spacing to the image sensor 140.

For the parameter values such as the radius of curvature and the spacing of each surface, please refer to Table 1, and will not be repeated here. Although the Abbe number is not limited in the miniature lens module 100, it is worth noting that the Abbe number of each lens still needs to be properly selected. Since the Abbe number is important for the design of the lens module, the data is also shown in Table 1. As shown in Table 1, the miniature lens module 100 satisfies the above situation.

The aforementioned surfaces S1, S2, S5 and S8 are even-order aspheric surfaces, and they can be expressed by the following formula:

Where Z(r) is the offset (sag) of the surface apex or the associated vertical line along the optical axis A, and c is the reciprocal of the radius of the osculating sphere, that is, the radius of curvature near the optical axis A. (The reciprocal of the radius of curvature of S1, S4, S5, and S8 in Table 1). k is a quadric coefficient (conic), r is an aspherical height, that is, a height from the center of the lens toward the edge of the lens, and α ₁ to α _{8 are} aspheric coefficients, and in this embodiment, the coefficient α ₁ is 0. Listed in Table 2 are the parameter values α ₂ ~ α ₈ of the surfaces S1, S4, S5, and S8.

1C and 1D are imaging optical simulation data diagrams of the micro lens module 100 of FIG. 1A. Referring to FIG. 1C and FIG. 1D, the left curvature to the right is a pattern of field curvature and distortion. In addition, FIG. 1D is a transverse ray fan plot of the image. As can be seen from the graphs shown in FIG. 1C and FIG. 1D, the micro lens module 100 of the present embodiment can exhibit good imaging quality with a miniaturized volume.

In order to have good image quality, the stray light generated by the micro lens module from each optical element is another problem. In order to eliminate stray light, limiting the light transmission path is an effective practice. 2 is a schematic view of a lens design in accordance with an embodiment of the present invention. Referring to FIG. 2, a lens 220 is supported by a light transmissive plate 240 and is designed to include a lens portion 220A and a carrier portion 220B integrally formed. In order to eliminate stray light, the surface of the carrying portion 220B is designed to be a matte surface except for the lens portion 220A which is a light transmitting path. Since the matte surface can reflect the diffused light, the amount of stray light is also reduced.

FIG. 3 is a schematic structural diagram of a micro lens module 300 according to another embodiment of the present invention. The first lens group 310 is disposed between the object side and the image side and includes a first lens 312, a first light transmissive plate 314 and a second lens 316 arranged in this order from the object side to the image side. The second lens group 320 is disposed between the first lens group 310 and the image side and includes a third lens 322, a second light transmissive plate 324, and a fourth lens arranged in sequence from the first lens group 310 to the image side. 326. A protective cover 330 disposed between the second lens group 320 and the image side for protecting the image processing device 340 between the protective cover 330 and the image side.

According to the exemplary embodiment, in the micro lens module 300, the first lens 312, the second lens 316, the third lens 322, and the fourth lens 326 respectively include an integrally formed lens portion (312A, 316A, 322A, and 326A). And a carrying portion (312B, 316B, 322B, and 326B). The bearing portion 312B of the first lens 312 faces the surface of the object side, the bearing portion 316B of the second lens 316 faces the image side surface, the bearing portion 322B of the third lens 322 faces the object side surface, and the bearing portion of the fourth lens 326 The surface of the 326B facing the image side is designed as a matte surface. The stray light generated by the respective optical elements can be eliminated by the matte surface on these lenses, so the stray light problem in the micro lens module 300 can be effectively solved. In an exemplary embodiment, the micro lens module 300 can satisfy the conditions satisfied by the micro lens module 100 and the parameters listed in Tables 1 and 2 above. It is to be noted that the parameters listed in the foregoing Tables 1 and 2 are not intended to limit the invention, and those skilled in the art can appropriately change the parameters or settings therein without departing from the scope of the invention.

4A through 4F illustrate a process for producing a matte surface on a lens using a molding process as described in an embodiment of the present invention. This molding process is as follows. Referring to FIG. 4A, a metal layer 410A having a smooth surface S is provided. Next, sandblasting is performed on the smooth surface to etch the surface as shown in Fig. 4B. Therefore, the surface S becomes rough and is no longer smooth. Thereafter, referring to FIG. 4C, a portion of the metal layer 410A is removed to form a metal mold 410B having a desired shape. Therefore, according to the present embodiment, a newly formed surface Sm is an aspherical surface and a mirror-like surface. However, the other part of the surface S, that is, the metal surface Smr is still rough.

In order to extend the total use time of the metal mold, a plastic mold is molded to have the same shape as the metal mold. This plastic molding is directly applied to the process of mass producing lenses instead of using the aforementioned metal mold. According to Fig. 4D, the metal mold 410B is applied to mold a plastic sub-mold 420 disposed on the glass plate 430A. Since the surface Sg is shaped by the surface Sm, the surface Sg is also an aspherical surface and a mirror-like surface. On the other hand, the surface of the other portion of the plastic sub-module 420, that is, the surface Sgr, is shaped by the rough Smr surface and is therefore rough. Referring to FIG. 4E, the plastic processing mold 440 disposed on the glass plate 430B is formed by molding the plastic sub-mold 420. The surface Sw is shaped by the surface Sg to become an aspherical and mirror-like surface, and the other surface of the plastic processing mold 440, that is, the surface Swr, is shaped by the rough surface Sgr and is therefore rough. Compared with FIG. 4C, the plastic working mold 440 has the same shape as the metal mold 410.

In FIG. 4F, the aspherical lens 450 is molded from a plastic molding die 440 and has two portions. The lens portion 450A is shaped by the surface Sw and is transparent and can serve as a light transmission path. Conversely, the bearing portion 450B is shaped by a rough surface Swr to form a matte surface.

In summary, according to an exemplary embodiment of the present invention, both the aperture stop and the infrared filter layer included in the first lens group are selectively disposed on the surface of the light transmissive plate to form a composite optical component. Therefore, a miniature lens module including a composite optical element and having good imaging quality has been miniaturized. In addition, each lens of the micro lens module has a lens portion and a bearing portion, and the surface of the bearing portion is designed to be a matte surface to reduce stray light.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

100, 300. . . Micro lens module

110, 310. . . First lens group

111. . . Aperture diaphragm

112, 312. . . First lens

113. . . Infrared filter layer

114, 314. . . First light transmission plate

116, 316. . . Second lens

120, 320. . . Second lens group

122, 322. . . Third lens

124, 324. . . Second light transmission plate

126, 326. . . Fourth lens

130, 330. . . protection cap

140, 340. . . Image sensor

220. . . lens

220A, 312A, 316A, 322A, 326A, 450A. . . Lens unit

220B, 312B, 316B, 322B, 326B, 450B. . . Carrying part

240. . . Translucent plate

S, Smr, Sgr, Swr, S1~S11. . . surface

Sm, Sg, Sw. . . Aspheric and mirror-like surface

A. . . Optical axis

L. . . Total length of the miniature lens module

L1. . . Distance between the first aspheric surface and the second aspheric surface

L2. . . The distance between the third aspheric surface and the fourth aspheric surface

T1. . . The distance between the second aspheric surface and the third aspheric surface

BFL. . . The distance between the fourth aspheric surface and the surface of the image processing device

410A. . . Metal layer

410B. . . Metal mold

420. . . Plastic submodel

430A, 430B. . . glass plate

440. . . Plastic processing molding

450. . . Aspheric lens

The accompanying drawings are intended to be a

FIG. 1A is a schematic structural view of a micro lens module according to an embodiment of the invention.

FIG. 1B is a schematic view of the first lens group of FIG. 1A.

1C and FIG. 1D are imaging optical simulation data diagrams of the micro lens module of FIG. 1A

2 is a schematic view showing the design of a lens according to an embodiment of the present invention.

FIG. 3 is a schematic structural diagram of a micro lens module according to another embodiment of the present invention.

4A through 4F illustrate a process for producing a matte surface on a lens using a molding process as described in an embodiment of the present invention.

100. . . Micro lens module

110. . . First lens group

112. . . First lens

114. . . First light transmission plate

124. . . Second light transmission plate

116. . . Second lens

120. . . Second lens group

122. . . Third lens

126. . . Fourth lens

130. . . protection cap

140. . . Image sensor

S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11. . . surface

A. . . Optical axis

L. . . Total length of the miniature lens module

L1. . . Distance between the first aspheric surface and the second aspheric surface

L2. . . The distance between the third aspheric surface and the fourth aspheric surface

T1. . . The distance between the second aspheric surface and the third aspheric surface

BFL. . . The distance between the fourth aspheric surface and the surface of the image processing device

Claims (17)

A micro lens module is applicable to an image processing device. The micro lens module includes: a first lens group disposed between an object side and an image side, wherein the first lens group is closest to the object side The surface of the first lens group is a second aspherical surface, and a second lens group is disposed between the first lens group and the image side. The surface of the second lens group closest to the first lens group is a third aspheric surface, and the surface closest to the image side of the second lens group is a fourth aspheric surface, wherein the micro lens module The total length is L, the effective focal length (EFL) of the micro lens module is f, the effective focal length of the second lens group is f2, and the micro lens module satisfies the following conditions: 1.5>L/f> 0.6, and -7>f2/f>-14. The micro lens module of claim 1, wherein the distance between the first aspheric surface and the second aspheric surface is L1, and the distance between the third aspheric surface and the fourth aspheric surface is L2, and the distance is The miniature lens module satisfies 1.3>L1/L2>0.8. The micro lens module of claim 1, wherein the image processing device is disposed on the image side, and the distance between the second aspheric surface and the third aspheric surface is T1, the fourth aspheric surface and the image The distance of one surface of the processing device is BFL, and the micro lens module satisfies 0.7>T1/BFL>0.4. The micro lens module of claim 1, wherein the first aspheric surface has a radius of curvature r1, the second aspheric surface has a radius of curvature r2, and the third aspheric surface has a radius of curvature of r3. The radius of curvature of the fourth aspherical surface is r4, and the micro lens module satisfies the following conditions: r1>0, r2>0, r3>0, and r4>0. The micro lens module of claim 1, wherein the first lens group comprises a first lens and a second lens arranged in sequence from the object side to the image side, wherein the first lens is the first lens a lens closest to the object side of the first lens group, a surface of the first lens facing the object side is the first aspheric surface, and the second lens is the closest to the second lens group of the first lens group a lens, and a surface of the second lens facing the image side is the second aspheric surface. The micro lens module of claim 5, wherein the first lens and the second lens have refractive indices n1 and n2, respectively, the first lens satisfies 1.61>n1>1.56, and the second lens Meet 1.55>n2>1.5. The micro lens module of claim 5, wherein the first lens group further comprises a first light transmissive plate. The micro lens module of claim 7, wherein the first lens group further comprises an aperture diaphragm. The micro lens module of claim 8, wherein the aperture diaphragm is disposed on a surface of the first light transmissive plate facing the object side. The micro lens module of claim 5, wherein the first lens group further comprises an infrared filter layer disposed on a surface of the first light transmissive plate. The microlens module of claim 5, wherein the first lens comprises an integrally formed lens portion and a bearing portion, and the surface of the first lens adjacent to the object side is a matte surface. . The micro lens module of claim 5, wherein the second lens comprises an integrally formed lens portion and a bearing portion, wherein the surface of the second lens adjacent to the image side is a matte surface . The micro lens module of claim 1, wherein the second lens group comprises a third lens and a fourth lens arranged in sequence from the first lens group to the image side, the third lens a lens of the second lens group closest to the first lens group, a surface of the third lens facing the first lens group is the third aspheric surface, and the fourth lens is the closest one of the second lens groups The image side lens, the surface of the fourth lens facing the image side is the fourth aspheric surface. The micro lens module of claim 13, wherein the third lens and the fourth lens have refractive indices n3 and n4, respectively, and the third lens satisfies 1.55>n3>1.5, and the fourth lens Meet 1.61>n4>1.56. The micro lens module of claim 13, wherein the second lens group further comprises a second light transmissive plate. The micro lens module of claim 13, wherein the third lens comprises an integrally formed lens portion and a bearing portion, and the surface of the third lens adjacent to the object side is a matte surface. . The micro lens module of claim 13, wherein the fourth lens comprises an integrally formed lens portion and a bearing portion, wherein the surface of the fourth lens adjacent to the image side is a matte surface .