KR100934365B1 - Auto Focus Camera Module - Google Patents

Abstract

The present invention relates to a structure of an auto focusing camera module that is used to linearly adjust the focus of an image in a camera module to make an elaborate photograph. When a current flows in a shape memory alloy wire, The lens module is moved upward by moving the protrusion upward, and when the current does not flow in the shape memory alloy wire, the lens module is moved downward by a spring connected to the protrusion.

Description

Auto Focus Camera Module

1 is a cross-sectional view schematically showing the structure of a camera module according to an embodiment of the prior art.

2 is a perspective view illustrating a structure of an auto focusing camera module according to an embodiment of the present invention.

3 is a cross-sectional view taken along line AA ′ of FIG. 2.

4 is a cross-sectional view illustrating a structure of an auto focusing camera module according to another embodiment of the present invention.

5 is a top view of the case removed in FIG.

6 is a cross-sectional view showing the structure of an auto focusing camera module according to another embodiment of the present invention.

7 is a cross-sectional view of another embodiment of the present invention.

FIG. 8 is a cross-sectional view illustrating only the lens module of FIG. 7.

The present invention relates to an autofocus camera module used to linearly adjust the focus of an image in a camera module to make an elaborate photograph, and more particularly, to a shape memory alloy having a property of shrinking when a certain amount of current is applied. It relates to a camera module that focuses by automatically moving the lens module using the characteristics of the wire.

Recently, cell phone cameras have entered the functional competition phase beyond pixel competition. In particular, more than 2 million pixels, the ability to improve the quality of the image rather than the pixel is a situation that emphasizes. As a result, demand for autofocus and optical zoom is expected to surge.

The auto focus function is a function that focuses by moving the lens module using a stepping motor, a piezoelectric motor, and a voice coil motor.It can be divided into a lens module and a driving mechanism in terms of parts. . There are two types of autofocus algorithms: active to detect the distance by returning light or ultrasonic waves to the subject, and passive to move the lens to obtain the best image by analyzing the frequency component of the image output signal. Most of the fields used are manual. The auto focusing mechanism moves the entire lens module in response to the direction signal and the focus driving signal, and the movement amount is about 0.4 mm.

1 schematically shows a structure of a camera module according to an embodiment of the prior art, in which an image sensor 1 is mounted on a printed circuit board 3 with a conductive metal wire 2 and installed thereon. The cross section for the structure.

The conventional method of adjusting the focus while moving the lens module adopts a method of adjusting the vertical movement while rotating by fastening the lens holder part 5 and the lens module 6 by a screw method. However, this method has the limitation of moving the entire lens module 6, reducing the size of the outer portion of the lens module, and narrowing the screw groove and the width of the corresponding thread, so that the movement of the lens module is extremely finely controlled. There is a great difficulty to do.

In order to implement an autofocus function in a high-pixel phone, a driving mechanism must be adopted as essential, but development of a dedicated driving mechanism has been delayed due to difficulty in miniaturization. In the meantime, the development of the drive mechanism has been delayed, not only because of the technical difficulties due to the miniaturization but also because there is no significant merit in terms of performance and price.

The characteristics of the drive mechanisms currently employed in camera phones are shown in Table 1 below.

Table 1

   Item    Stepping motor     Voice coil motor     Piezoelectric linear motor    principle Mechanically driven by gear and motor that rotates a certain angle at a time Directly drives the barrel by passing current through a coil placed between the poles Drives simple vibrations of piezoelectric ceramics into linear motion   responsibility          ◎            △           ×   Miniaturization          △            ○           ◎  Control function          ○            ◎           ○   resolution          ○            ◎           ○  Power Consumption          ○            ○           ○    price          △            ○           ×

(◎: Very good ○: Good △: Normal ×: Bad)

Of the above auto focusing driving methods, one of the methods cannot be said to be absolutely advantageous over the other method, and both of them can lead the market only by minimizing disadvantages and having a price competitiveness.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problem of the autofocus driving method of a lens used in the conventional light and small short photographing device as described above, and is applied to the light and small short size, yet has a cost-effective autofocus. To provide a driving camera module.

Another object of the present invention is to apply a controlled power source to compensate for changes in external temperature to the shape memory alloy wires sensitive to external temperature changes, and to utilize the characteristics of the shape memory alloy wires to shrink and relax constantly. This is for automatically and easily adjusting the lens focus in a photographing device.

Another object of the present invention is to solve the problem of miniaturization and minimize the process by operating the autofocus drive mechanism by directly connected to the lens holder in the camera module manufacturing process without using a separate autofocus adjustment barrel that the existing technologies had It is to provide an ultra low cost auto focus camera module.

Features of the present invention to achieve the above object is a lens holder having an installation hole therein and at least one or more slits on the wall; A lens module seated in an installation hole of the lens holder part, having a protrusion through the slit to protrude out of the lens holder part, and moving up and down in the installation hole as the protrusion moves up and down along the slit; A shape memory alloy wire which contracts or relaxes according to the size of the applied power, and is connected so that a force for raising the protrusion is applied upon contraction; And an elastic member installed on the protrusion to move the protrusion downward when the shape memory alloy wire is relaxed.

In addition, in the present invention, the lens holder portion has a cylindrical portion, two cylindrical slits are formed on the cylindrical portion, two projections are formed on the lens module, and each projection protrudes outward through the slits. And both ends of the shape memory alloy wire are provided at each of the protrusions, and a portion of the shape memory alloy wire is in contact with the upper portion of the cylindrical portion, so that the shape memory alloy wire is upwardly raised to the protrusions when contracted. It is preferable to add.

In the present invention, it is preferable that an elastic member having a restoring force for lowering the protrusion is provided between the protrusion and the non-moving portion including the lens holder.

In addition, in the present invention, the lens holder portion has a cylindrical portion, one slit is formed in the cylindrical portion, one projection is formed in the lens module, the protrusion passes through the slit and protrudes outward, Both ends of the shape memory alloy wire may be installed at non-moving portions including the lens holder part, and the protrusions may be installed to contact the length center of the shape memory alloy wire.

In the present invention, it is preferable that an elastic member having a restoring force for lowering the protrusion is provided between the protrusion and the non-moving portion including the lens holder.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. In addition, in adding reference numerals to the components of the following drawings, the same components should have the same reference numerals as much as possible even if displayed on different drawings, but it is determined that they may unnecessarily obscure the subject matter of the present invention. Detailed descriptions of well-known functions and configurations will be omitted.

2 is a perspective view illustrating a structure of an auto focusing camera module according to an embodiment of the present invention, and FIG. 3 is a cross-sectional view taken along line AA ′ of FIG. 2.

2 to 3, the auto focusing camera module of the present invention includes a lens holder part 50 including a base 52 and a cylindrical part 51 formed on an upper portion of the base 52 on a circuit board 30. And a lens module 60 installed in the installation hole formed at the center of the lens holder part 50. An image sensor 10, an IR filter 40, and a conductive metal wire 20.

On the wall surface of the cylindrical part 51 of the lens holder part 50, two slits 53 and 54 which are formed to face each other are formed up and down by a predetermined length, and the slits 53 and 54 are formed. Two support bars 55 and 56 protrude from the upper end of the outer circumferential surface on the extension line. In addition, a locking bar 57 protrudes from an intermediate portion where the slit 53 and the slit 54 of the outer circumferential surface of the cylindrical portion 51 are formed.

In addition, the outer peripheral surface of the lens module 60 is provided with protrusions 61 and 62 which protrude to the outside of the cylindrical portion 51 through the slits 53 and 54, and various lenses are installed therein. .

Springs 81 and 82 are provided at the ends of the protrusions 61 and 62, respectively. The springs 81 and 82 are fixed at the lower end to the upper surface of the base 52, and the upper ends are fixed to the protrusions 61 and 62, respectively, and are made of a conductive material. In addition, the start and end of the shape memory alloy wire 90 is connected to the protrusion 61 and the protrusion 62. At this time, the start and end of the shape memory alloy wire 90 is connected to the electrical connection with the spring 81, 82, respectively, when the power is supplied to the spring 81, 82, the shape memory alloy wire 90 An electric current flows in such a way that the length of the shape memory alloy wire 90 is varied by a potential difference.

The shape memory alloy wire 90 is made of a material whose length is varied by a potential difference between both ends, and is preferably made of lintinol wire.

The shape memory alloy wire 90 has a start end at the protrusion 61 and is bent downward at the support bar 55 and then bent upward at the latch bar 57 and then bent downward at the support bar 56 to be hooked ( Terminating at 62). Therefore, when the potential difference is applied to the shape memory alloy wire 90 and the length is reduced, the protrusions 61 and 62 are moved upward by the shape memory alloy wire 90, so that the lens module 60 is moved upward. . When no potential difference is applied to the shape memory alloy wire 90 in this state, the protrusions 61 and 62 are moved downward by the restoring force of the springs 81 and 82, and eventually the lens module 60 Moves downward.

As such, the lens module 60 may be finely adjusted by the shape memory alloy wire 90 and the spring, and the temperature compensation control system is provided to correct the shrinkage ratio of the shape memory alloy wire 90 that varies according to the external environment temperature. You can do it.

The shape memory alloy wire 90 is made of nitinol wire, and its thickness and length are not limited, but a thickness of 25 μm to 500 μm and a length of 2 mm to 50 mm is preferable, and the shrinkage limit is preferably 25 μm to 1000 μm. .

4 is a cross-sectional view illustrating a structure of an auto focusing camera module according to another embodiment of the present invention, and FIG. 5 is a top view of the case removed in FIG. 4.

One slit 58 is formed in the lens holder part 50 illustrated in FIGS. 4 and 5, and one projection 63 is formed in the lens module 60 to protrude outward through the slit 58. , The spring 80 is connected between the protrusion 63 and the base 52.

While the structure of the auto focusing camera module according to the embodiment of FIGS. 2 and 3 is to connect springs to both ends of the shape memory alloy wire 90 and to supply power, the embodiment of FIGS. 4 and 5 According to the auto focus camera module structure, the conductive material spring 80 is connected between the projection 63 and the base 52 of the lens module 60. In addition, the shape memory alloy wire (90) has an upper end (110) and an end (110 ') on the upper portion of the case 100, so that the middle portion is bent over the projection (63), the shape of the memory alloy wire (90) A potential difference is applied between the start end and the lower end of the spring 80, and a potential difference is applied between the end of the shape memory alloy wire 90 and the lower end of the spring 80 so that current flows through the spring and the shape memory alloy wire 90. The lens module 60 is moved finely.

6 is a cross-sectional view showing the structure of an auto focusing camera module according to another embodiment of the present invention.

Referring to FIG. 6, it can be seen that the auto focus control is implemented by applying the technique of the present invention to the general known camera module structure of FIG. 1.

That is, after completing the general camera module package process of FIG. 1, the elastic steel wire 120 together with the shape memory alloy wire 90 on the screw thread of the lens module 60 is wound at least 0.5 times at both ends. The potential difference is applied to the shape memory alloy wire 90 to flow a current. When the current flows through the shape memory alloy wire 90, the shape memory alloy wire 90 is moved by rotating the lens module 60 left and right in a screw direction as the contraction or relaxation of the shape memory alloy wire 90 adjusts the focus of the lens module. It is a matching structure. At this time, when the current does not flow in the shape memory alloy wire 90 is rotated to the original position by the restoring force of the steel wire 120 having elasticity.

When the shape memory alloy wire 90 is wound from the upper part of the thread, it is preferable that one or more windings are wound down in the spiral direction (spiral).

In the present invention, a simple and convenient process can be added once more without changing the existing camera module process to enable fine focus adjustment in units of micrometers.

Therefore, according to an embodiment of the present invention, it is possible to apply an auto focus control process using an existing camera module without producing a new camera module structure, thereby improving the usability and economy.

Structures according to one embodiment of the present invention can all proceed during the general camera module package process, and can reduce the number of processes by using the autofocus drive mechanism in the focusing process after assembling the lens in the existing camera module process In addition to the simple structure, the module can be miniaturized, and the structures can be lowered at a low cost.

FIG. 7 is a cross-sectional view of another embodiment of the present invention, and FIG. 8 is a cross-sectional view illustrating only the lens module of FIG. 7.

7 and 8, the lens module is installed in the outer lens module 130 and the outer lens module 130 including a disk having a circular opening at the center and a cylindrical part having a diameter larger than the opening at the bottom of the disk. The inner lens module 150 and the upper surface of the inner lens module 150 and the cylindrical shape and the shape memory alloy wire 90 having a spring shape is installed in the space formed by the disc.

In addition, a thread is formed on the outer circumferential surface of the cylindrical part of the outer lens module 130, and when the screw is inserted into the thread of the inner wall of the lens holder part 50 like a screw, the outer lens module 130 is fixed and the shape memory alloy wire ( When the power is applied to 90, only the internal lens module 150 may move up and down according to the application of power.

Due to the elasticity of the spring-shaped shape memory alloy wire 90, the internal lens module 15 is fixed downward when no current flows, and when power is applied, current flows to the shape memory alloy wire 90 so that the wire Due to the contraction of, the inner lens module rises to focus.

The power supply of the shape memory alloy wire 90 of the auto focus control camera module according to an embodiment of the present invention may include a control unit for temperature compensation of the auto focus control camera module.

This is because the shrinkage of the shape memory alloy wire 90 can be sensitively affected by the external environment, in particular temperature, the circuit that can be applied to the controlled power to reduce the error range of operation according to temperature It is included in the power supply.

This allows precise micrometer (μm) displacement control in spite of external environmental changes by incorporating a compensation circuit for changes in displacement characteristics of nitinol wires due to external temperature.

The automatic focusing mechanism of the camera module using the shape memory alloy wire can be applied not only to a general digital camera module but also to various parts such as a phone camera such as a mobile phone, a surveillance camera, and a camera applied to a robot.

As described above, the present invention has been described with reference to a preferred embodiment of the present invention, but those skilled in the art can vary the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. It will be appreciated that modifications and variations can be made.

As described above, according to the present invention, since the driving of the lens module is driven in a completely new way by using the characteristics of the shape memory alloy wire, it is possible to implement the precise autofocus driving suitable for the light and small camera module structure.

In addition, since the camera module can control the movement of the lens module in a simple and minimal process, the production cost can be lowered, resulting in price competitiveness and economic value creation.

And since it can be applied to the production process of the general camera module, there is an advantage that can be manufactured using the existing camera module production process.

Claims (5)

A lens holder having an installation hole therein and having at least one slit on a wall thereof; A lens module seated in an installation hole of the lens holder part, having a protrusion through the slit to protrude out of the lens holder part, and moving up and down in the installation hole as the protrusion moves up and down along the slit; A shape memory alloy wire which contracts or relaxes according to the size of the applied power, and is connected so that a force for raising the protrusion acts upon contraction; And By including the elastic member is provided in the protrusion so that the shape memory alloy wire to move the protrusion downwards at the time of relaxation, And the lens module is linearly moved according to the magnitude of the applied power. The method of claim 1, wherein the lens holder portion has a cylindrical portion, two cylindrical slits are formed in the cylindrical portion, two projections are formed in the lens module, each projection is projected out through the slits And both ends of the shape memory alloy wire are provided at each of the protrusions, and a portion of the shape memory alloy wire is in contact with the upper portion of the cylindrical portion, so that the shape memory alloy wire is upwardly raised to the protrusions when contracted. Auto focusing camera module, characterized in that for applying a. The auto focus camera module of claim 2, wherein an elastic member having a restoring force for lowering the protrusion is installed between the protrusion and the non-moving part including the lens holder. The method of claim 1, wherein the lens holder portion has a cylindrical portion, one slit is formed in the cylindrical portion, one projection is formed in the lens module, the protrusion passes through the slit and protrudes outward, Both ends of the shape memory alloy wires are respectively installed on the non-moving part including the lens holder portion, and the auto focusing camera module, characterized in that the projection is installed in contact with the length center of the shape memory alloy wire. The auto focus camera module of claim 4, wherein an elastic member having a restoring force for lowering the protrusion is installed between the protrusion and the non-moving part including the lens holder.

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