KR100702597B1 - Lens assembly of camera module - Google Patents

Abstract

 A lens assembly of a camera module is disclosed. In the lens assembly of the camera module, the use of one or more light-transmitting ceramic lenses having a refractive index of 1.9 or more can achieve high pixels.

Ceramics, camera module

Description

 Lens assembly of camera module {Lens assembly of camera module}

1 is an exploded perspective view of a camera module according to the prior art.

2 is a cross-sectional view of a lens assembly coupled to a barrel according to the prior art.

3 is a cross-sectional view of a lens assembly according to a first preferred embodiment of the present invention.

4 is a cross-sectional view of a lens assembly according to a second preferred embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

5: lens assembly 34: press ring

41: first lens 42: second lens

43: third lens

The present invention relates to a camera module, and more particularly to a lens assembly of the camera module.

The camera module is a device that converts an external subject into a digital signal, and is widely used in a mobile phone and a small digital camera. The structure of the camera module undergoes a process of receiving an image of a subject through a lens and an aperture by a high image pickup device, which is an image sensor, and converting it into a digital signal and storing it in a memory unit.

Here, the image sensor is a CMOS image sensor, and the CMOS image sensor uses a CMOS technology using a control circuit and a signal processing circuit as peripheral circuits to make MOS transistors as many as the number of pixels. It is a device using a switch system which detects an output one by one. The CMOS image sensor is very useful for personal portable devices such as mobile phones because it has the great advantage of low power consumption.

1 is an exploded perspective view of a camera module according to the prior art. Referring to FIG. 1, a silver barrel 1, a lens assembly 5, a housing 2, an image sensor 3, a printed circuit board 4, a micro lens 8, a guide pin 6, and a pin hole (7) is shown.

 Barrel (1) is made of a plastic material is a screw thread on the outer peripheral surface of the barrel 1 is screwed with the inner peripheral surface of the housing (2).

Meanwhile, the lens assembly 5 stacks several lenses having different refractive indices so that an external subject is focused on the image sensor 3 inside the camera module 10. The lens assembly 5 is inserted and fixed inside the barrel 1.

If the focus is not correct, the lens assembly 5 is focused on the image of the object reaching the image sensor 3 by loosening or tightening the barrel 1.

The housing 2 is coupled to a printed circuit board 4 to which the image sensor 3 is attached. Looking at the coupling method of the housing 2 in detail, a plurality of guide pins 6 protruding from the lower edge of the housing 2, it can be fitted to the pinhole 7 of the corresponding printed circuit board (4). .

 The image sensor 3 is attached to the printed circuit board 4 and the microlens 8 is coated on the upper surface. When the subject is placed on the microlens 8 through the lens assembly 5, the image is converted into an electronic signal through the image sensor 3.

2 is a cross-sectional view of a lens assembly coupled to a barrel according to the prior art. 2, the barrel 1, the first lens 41, the second lens 42, the third lens 43, the spacers 33a and 33b, and the press ring 34 are illustrated. .

In the lens assembly 5, a plurality of lenses 41, 42, and 43 are overlapped with spacers 33a and 33b interposed therebetween. The spacers 33a and 33b serve to maintain a constant separation distance between the lens and the lens. In addition, there is a press ring 34 at the bottom of the barrel 1 to protect the barrel inner lens assembly 5.

In the camera module, the lens serves to transmit the optical information emitted from the subject to the image sensor as described above. Recently, there is an urgent need for miniaturization of high pixel size of such a camera module. In order to satisfy the desire for high pixel size, it is required to secure performance by increasing the number of lenses, which makes it difficult to meet the demand of miniaturization. Therefore, there is a demand for an optical element having a high refractive index. However, the plastic-based materials used in the past do not exceed the refractive index of 1.7 and the glass is also 1.9 levels, there is a limit in reducing the size of the camera module.

An object of the present invention is to provide a lens assembly of a camera module that satisfies the requirements of high pixel size and size without increasing the number of lenses.

 According to an aspect of the present invention, in the lens assembly of a plurality of camera module, to provide a lens assembly of the camera module using at least one lens of the transparent ceramics.

Translucent ceramics have a refractive index of 1.9 or more and are preferably dielectric. Here, the dielectric constant does not substantially change the dielectric constant even when an electric field is applied, and thus does not cause birefringence. That is, the translucent ceramic of the present invention is a dielectric material and is a polycrystal, so that its birefringence is not generated, and its application range is wider than that of a single crystal having birefringence, and thus it can be applied to an optical component such as a lens. In addition, since the refractive index is 1.9 or more, it is relatively small in size, so that the optical component can be miniaturized.

Hereinafter, a preferred embodiment of a lens assembly of a camera module according to the present invention will be described in detail with reference to the accompanying drawings, in the following description with reference to the accompanying drawings, the same or corresponding components regardless of reference numerals refer to the same reference The numbering and duplicate description thereof will be omitted.

3 is a cross-sectional view of a lens assembly according to a first exemplary embodiment of the present invention. Referring to FIG. 3, the first lens 41, the outer side 41a of the first lens, the inner side 41b of the first lens, the second lens 42, the outer side 42a of the second lens, and the second lens The inner side 42b, the third lens 43, the outer side 43a of the third lens, the inner side 43b of the third lens, the press ring 34, the image sensor 3, and the optical axis 40 are shown. have.

In the drawing, three lenses are arranged, the first lens 41 is made of a transparent ceramic material, and the remaining second and third lenses 42 and 43 are plastic lenses.

The center line in the figure represents the optical axis 40. The remaining lines represent the path through which light is incident and transmitted.

The lens used in the first embodiment is an aspherical lens, and the aspherical shape of each lens is represented by the following aspherical function.

Z in the above formula is a SAG value and is a function of Y. Y represents the distance from the optical axis. CURV represents the inverse of the radius (1 / radius) without considering the aspherical surface. K is the Conic Constant, and A, B, C, D, E, and F are aspherical coefficients.

Looking at the specific shape of the lens assembly according to the first embodiment of the present invention corresponding to the above formula, when the outer side (41a) of the first lens does not consider the aspherical surface, the radius is 2.23228mm, the thickness is 0.618257mm , K: -0.286159, aspherical coefficients are A: 0.474807E-02, B: 0.326835E-01, C: -0.656407E-01, and D: 0.879177E-01. When the inner surface 41b of the first lens is not considered aspherical, the thickness is 0.137272 mm, K is -3.562122, and the aspherical surface coefficient is A: 0.153969E-01, B: 0.175701E + 00, C: -0.631139E + 00, D: 0.100456E + 01, E: 0.255290E-0.1.

The outer surface 42a of the second lens has a radius of -7.07813 mm, a thickness of 0.875079 mm, K: -11.124769, and an aspherical coefficient of A: -0.545306E-01, B: 0.121886E + 00 , C: -0.86634E-01, D: 0.332148E-01, E-0.335668E-07. The inner surface 42b of the second lens has a radius of -0.94498 mm when the aspheric surface is not taken into account, K: -2.923393, and aspherical coefficients A: -0.555511E-01, B: 0.761788E-02, and C: 0.485028E-. 01, D: 0.276463E-02, E: -0.626556E-02

When the outer side 43a of the third lens is not considered aspherical, the radius is -6.06056 mm, the thickness is 0.550000 mm, K is 3.99162, and the aspherical coefficient is A: -0.859245E-01, B: 0.208815E-01 , C: 0.779970E-02, D: 0.807768E-03, and E-0.820631E-03. When the inner side 43b of the third lens does not consider the aspherical surface, the radius is 1.36091 mm, K is -8.989604, and the aspherical surface coefficient is A: -0.812306E-01, B: 0.144124E-01, C: -0.179372E -02, D: -0.292812E-03 and E: 0.707409E-04.

Thus, the characteristics of each lens used in the lens assembly according to the first embodiment of the present invention are summarized in the following table.

location Material Radius (unit mm, if aspherical surface is not taken into account) Thickness (mm) Conic Constant and Aspheric Coefficients 1a (outer side of the first lens, 41a) Translucent ceramics 2.23228 0.618257 K: -0.286159 A: 0.474807E-02 B: 0.326835E-01 C: -0.656407E-01 D: 0.879177E-01 E-0.359171E-01 1b (inside of first lens, 41b) 3.30887 0.137272 K: -3.562122 A: 0.153969E-01 B: 0.175701E + 00 C: -0.631139E + 00 D: 0.100456E + 01 E: 0.255290E-0.1 2a (outside of second lens, 42a) Plastic series -7.07813 0.875079 K: -11.124769 A: -0.545306E-01 B: 0.121886E + 00 C: -0.86634E-01 D: 0.332148E-01 E-0.335668E-07 2b (inside of second lens, 42b) -0.94498 0.100000 K: -2.923393 A: -0.555511E-01 B: 0.761788E-02 C: 0.485028E-01 D: 0.276463E-02 E: -0.626556E-02 3a (outside of the third lens, 43a) Plastic series -6.06056 0.550000 K: 3.99162 A: -0.859245E-01 B: 0.208815E-01 C: 0.779970E-02 D: 0.807768E-03 E-0.820631E-03 3b (inside of third lens, 43b) 1.36091 0.157697 K: -8.989604 A: -0.812306E-01 B: 0.144124E-01 C: -0.179372E-02 D: -0.292812E-03 E: 0.707409E-04

4 is a cross-sectional view of a lens assembly according to a second exemplary embodiment of the present invention. Referring to FIG. 4, the first lens 41, the outer side 41a of the first lens, the inner side 41b of the first lens, the second lens 42, the outer side 42a of the second lens, and the second lens The inner side 42b, the third lens 43, the outer side 43a of the third lens, the inner side 43b of the third lens, the press ring 34, the image sensor 3, and the optical axis 40 are shown. have. The second embodiment is a case where the third lens 43 is used as the transparent ceramic material.

Looking at the specific form of the second embodiment, when the outer side (41a) of the first lens is not considered aspherical, the radius is 1.32805mm, the thickness is 0.881217mm, K: -0.537923, the aspherical surface coefficient A: 0.233965E- 02, B: 0.238853E-01, C: -0.395229E-01, and D: 0.966892E-01. When the inner surface 41b of the first lens is not considered aspherical, the radius is 3.47600 mm, and K is -11.166325, and the aspherical coefficient is A: 0.401373E-01, B: 0.558781E + 00, and C: -0.151978E + 00, D: 0.157427 + 01, and E: -0.152210E-0.1.

The outer surface 42a of the second lens has a radius of -2.80253mm, a thickness of 0.560000mm, K: 8.113404, and an aspherical coefficient of A: -0.325078E-01 and B: -0.274964E + 00 without considering the aspherical surface. , C: 0.224263E + 00, D: 0.236741E + 00, and E-0.136255E + 01. The inner surface 42b of the second lens has a radius of 22.81631 mm when the aspherical surface is not taken into account, K: -10.000000, and aspherical coefficients A: -0.215341E + 00, B: 0.102705E + 00, and C: -0.39587E-. 01 E-0.136255E + 01

When the outer surface 43a of the third lens is not considered aspherical, the radius is 2.14170 mm, the thickness is 0.755618 mm, K is -7.099114, and the aspherical coefficient is A: -0.465105E-01, B: 0.700869E-02 , C: 0.692736E-02, D: 0.308707E-03, E-0.809640E-03. The inner surface 43b of the third lens has a radius of 3.26409 mm when the aspherical surface is not taken into account, and K: -2.960539, and aspherical coefficients are A: -0.55132E-01, B: 0.438768E-01, and C: 0.110121E-02. , D: -0.155652E-03, E: -0.166783E-04.

Thus, the characteristics of each lens used in the lens assembly according to the second embodiment of the present invention are summarized in the following table.

location Material Radius (unit mm, if aspherical surface is not taken into account) Thickness (mm) Aspheric modulus 1a (outside of first lens, 41a) Plastic series 1.32805 0.881217 K: -0.537923 A: 0.233965E-02 B: 0.238853E-01 C: -0.395229E-01 D: 0.966892E-01 1b (inside of first lens, 41b) 3.47600 0.129799 K: -11.166325 A: 0.401373E-01 B: 0.558781E + 00 C: -0.151978E + 00 D: 0.157427 + 01 E: -0.152210E-0.1 2a (outside of second lens, 42a) Plastic series -2.80253 0.560000 K: 8.113404 A: -0.325078E-01 B: -0.274964E + 00 C: 0.224263E + 00 D: 0.236741E + 00 E-0.136255E + 01 2b (inside of second lens, 42b) 22.81631 0.266796 K: -10.000000 A: -0.215341E + 00 B: 0.102705E + 00 C: -0.39587E-01 D: 0.3345004E-02 E: -0.434174E-02 3a (outside of the third lens, 43a) Translucent ceramics 2.14170 0.755618 K: -7.099114 A: -0.465105E-01 B: 0.700869E-02 C: 0.692736E-02 D: 0.308707E-03 E-0.809640E-03 3b (inside of third lens, 43b) 3.26409 0.112719 K: -2.960539 A: -0.55132E-01 B: 0.438768E-01 C: 0.110121E-02 D: -0.155652E-03 E: -0.166783E-04

Although the technical spirit of the present invention has been described in detail according to the above-described embodiments, the above-described embodiments are for the purpose of description and not of limitation, and a person of ordinary skill in the art will appreciate It will be understood that various embodiments are possible within the scope.

According to the present invention having such a configuration, it is possible to provide a lens assembly of a camera module that satisfies the requirements of high pixel size and miniaturization without increasing the number of lenses by using translucent ceramics having a refractive index of 1.9 or more.

Claims (4)

In the lens assembly of the camera module consisting of a plurality of lenses, At least one of the plurality of lenses of the lens assembly of the camera module comprises a transparent ceramic material. The method of claim 1, The transparent ceramic material is a lens assembly of the camera module has a refractive index of 1.9 ~ 2.5. The method of claim 1, The translucent ceramic is the lens assembly of the camera module dielectric. The method of claim 1, The translucent ceramic is a lens assembly of a camera module which is a polycrystal that does not generate birefringence.

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