KR100771827B1 - Apparatus for focusing and method of auto-focusing of camera module - Google Patents

Abstract

The present invention relates to a focusing device and an autofocusing method of a camera module, the camera module focusing device for adjusting the focus of a camera module having a lens and an image sensor, used to adjust the focus of the camera module Located between the test chart having a test pattern and the camera module, the enlarged detected by the image sensor connected to the camera module and the projector for expanding and providing the pattern of the test chart to the camera module And a focus adjuster for adjusting a position of the lens to optimize an image of a pattern, and an autofocusing method of the camera module.

According to the present invention, the focusing work space can be minimized, and the focus rate can be automated to improve the generation of a defective rate by manual work.

Camera Module, Focusing Apparatus, Auto-Focus

Description

Camera module focusing device and autofocusing method {APPARATUS FOR FOCUSING AND METHOD OF AUTO-FOCUSING OF CAMERA MODULE}

Figure 1a is a layout view of a conventional camera module focusing device.

1B is a chart for a conventional camera module focusing process.

2 and 3 are layout views of the focusing device of the camera module for the focusing step of the camera module according to an embodiment of the present invention.

4 is a flowchart for autofocusing of a camera module according to the present invention.

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

11, 21: Camera module 11a, 21a: Lens

11b, 21b: image sensor 12, 22: test chart

23: projector 23a: lens 1

23b: lens 2 24: light panel

25: Virtual Test Chart 31: Focus Adjuster

32: switch 33: control unit

34: control unit

The present invention relates to a focusing apparatus and an autofocusing method of a camera module, and more particularly, to a focusing apparatus of a camera module using a projector and an autofocusing method for focusing the camera module.

Recently, with the development of multimedia technology, the portable small devices have been provided with a function of capturing images, thereby making the portable small devices more versatile. In order to provide such a function, mounting of a camera module is essential. The camera module must be shipped with focus adjusted through a focus adjustment process before a product is released.

Conventionally, for the focusing process, a test chart having a test pattern is photographed with a camera module, and then a method of adjusting the focus of the camera module is used while checking the photographed result with a monitor.

According to the conventional method, the test chart and the camera module should be kept at a certain distance, and the distance should be longer as the resolution of the camera module increases. In addition, since the focusing process is a manual operation method in which the operator adjusts the focus according to the operator's experience, the focus is often adjusted differently depending on the operator, and thus there is a problem in the accuracy and working time of the focusing adjustment.

1A and 1B are a layout view and a chart of the camera module for the focusing process of the camera module by the conventional method.

As shown in FIG. 1A, the test chart 12 used for focusing is installed at a predetermined distance H from the camera module 11. The camera module includes a lens 11a and an image sensor 12a.

The test chart 12 is printed with a test pattern for focus adjustment as shown in FIG. 1B, and the camera module 11 captures the test chart 12, and the captured image is displayed on a display device such as a monitor. If not shown, the operator checks the characteristics of moiré and the like that appear on the display device (not shown) according to the test pattern of the test chart 12 and manually between the lens 11a and the image sensor 11b. The focus is adjusted while adjusting the distance of.

According to the conventional method, the distance H between the camera module 11 and the test chart 12 depends on the resolution of the camera module. In the case of a 300,000-pixel camera, the distance H is about 0.4 m. For example, the camera module of 1.3 million pixels should be 0.95 to 1.2 m and the camera module of 2 to 3 million pixels should be 5 m or more, and the size of the test chart 12 should be increased accordingly.

Therefore, according to the conventional method, in order to produce a high resolution camera module, the focusing process cannot be performed using the existing production line, and even if a new production line is installed, a large work space is required.

In addition, according to the conventional method, the lens 11a and the image sensor 11b are manually checked while the operator directly checks the test pattern 11b of the test chart 12 appearing on the display device (not shown). Since the work of adjusting the distance of), there is a problem that the quality of the product is different according to the skill of the operator, and the working time by manual operation is also long.

The present invention has been proposed to solve the above problems of the prior art, the object of which is to provide a projector between the test chart and the camera module to reduce the distance between the test chart and the camera module to minimize the work space, By providing an auto focusing method to the focusing process to automate the process, it is to minimize the defects caused by deviation between workers.

In order to achieve the above technical problem, the present invention, in the camera module focusing device for adjusting the focus of the camera module having a lens and an image sensor, provided with a test pattern used to adjust the focus of the camera module Located between the test chart and the camera module, the projector is connected to the projector and the projector for expanding and providing the test pattern of the test chart to the camera module, and of the enlarged test pattern detected by the image sensor. It provides a camera module focusing apparatus comprising a focus adjuster for adjusting the position of the lens to optimize the image.

Preferably, the projector may be provided with a relay lens, and more preferably, the projector may provide a test pattern of the test chart to the camera module without changing the distance between the test chart and the camera module. To this end, the enlargement ratio may be changed according to the type and resolution of the camera module.

In an embodiment of the present invention, the test chart may further include a light panel for irradiating light to the test chart and allowing a test pattern image transmitted through the test chart by the light to be irradiated toward the projector and the camera module. Can be.

In another embodiment of the present invention, the lens and the image sensor are screwed together, and the focus adjuster mechanically rotates the lens to adjust the distance between the lens and the image sensor to adjust the focus of the camera module. Preferably, the driving device for rotating the focus adjuster, the switch for generating a start signal of the focusing operation of the camera module and the distance between the lens of the camera module and the image sensor, and at each distance And a controller for analyzing the image signal from the camera module to obtain a distance between the lens and the image sensor having the optimal focus, and controlling the driving device so that the lens and the image sensor have the distance. More preferably, the drive device includes a DC step motor One can.

In addition, the present invention, a) obtaining a video signal of the test signal examined by the camera module, b) extracting a luminance signal in a predetermined region of the obtained image signal, and the luminance signal is a high pass filter Extracting the contour component of the predetermined region by passing through the image, integrating the contour component, and calculating the autofocus value by squaring the integrated value; and c) changing the distance between the lens of the camera module and the image sensor. And repeating steps a) and b) until the autofocus value has a preset maximum value.

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In one embodiment of the present invention, a predetermined region of the obtained image signal may be a plurality of regions in order to more accurately adjust the focus.

Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment of the present invention.

2 and 3 are layout views of the camera module focusing apparatus according to the embodiment of the present invention.

As shown in FIG. 2, the camera module focusing apparatus according to the exemplary embodiment of the present invention is disposed in the order of the light panel 24 test chart 22, the projector 23, and the camera module 21.

The light panel 24 irradiates light to the test chart 22, and a test pattern image transmitted through the test chart 22 by the light is irradiated toward the projector 23 and the camera module 21. To be possible. In this case, the test chart 22 may be a test pattern printed on a transparent material, the test pattern may be the same as the test pattern printed on the test chart used in the conventional method shown in FIG.

The projector 23 is to enlarge the test pattern of the test chart 22 and provide it to the camera module. The image of the test chart enlarged by the projector 23 and provided to the camera module 21 is a test. The location of the chart provides the same effect as the location of the virtual test chart 25. Therefore, when the projector 23 does not exist as shown in FIG. 1, the distance between the test chart 12 and the camera module should be H, but the test chart 22 is reduced to H 'by the projector 23 so that the focus is reduced. The adjusting process may be performed in a narrower space than the conventional one, and the test chart 22 may also be smaller than the conventional test chart 12.

More preferably, the projector 23 may be a relay lens, and as illustrated in FIG. 2, the projector 23 may have a lens 1 23a and a lens 2 23b. By adjusting the distance d1 between the lens 1 23a and the lens 2 23b, the enlargement ratio of the projector 23 can be adjusted. Therefore, by adjusting the distance d1, the test chart 22 is adjusted. There is an effect that can adjust the distance (H) between the virtual test chart 25 and the camera module 21 without adjusting the distance (H ') between the camera module 21 and. Therefore, when the resolution of the camera module 21 is different, only a distance d1 between the lens 1 (23a) and the lens 2 (23b) is provided to provide an appropriate test pattern to the camera module so that a single production line A focus adjustment process can be performed on the product. In addition, the same test chart may be used without separately manufacturing the test chart 22 according to the resolution of the camera module 21.

The test pattern image is enlarged by the projector 23 and sent to the camera module 21, and the image sensor 21b of the camera module 21 is connected to the test pattern of the test chart that has passed through the projector. Converts the video into a video signal. The image signal is displayed on a display device (not shown) through an image processor (not shown) or the like, and an optimal focus state is analyzed by analyzing a test pattern displayed on the display device (not shown) by a focus adjuster (not shown). The distance d2 between the lens 21a and the image sensor 21b is adjusted to be.

In the focus adjusting apparatus shown in FIG. 3, a switch 32, a controller 33, a focus adjuster 31, and a driving device 34 are added to the aforementioned focus adjusting apparatus.

The switch 32 generates a start signal of a focus adjustment operation of the camera module 21, and the control unit 33 controls the focus adjustment operation by the start signal.

The focus adjuster 31 is used to adjust the focus of the camera module 21. The lens 21a and the image sensor 21b of the camera module 21 are screwed together and the focus adjuster 31 is connected to the lens ( The focus of the camera module 21 is adjusted by mechanically rotating 21a by the driving device 34 to adjust the distance d2 between the lens 21a and the image sensor 21b.

The driving device 34 adjusts the distance d2 between the lens 21a and the image sensor 21b by rotating the focus adjuster 31 according to the control signal of the controller 33. The driving device 34 may include a DC step motor.

The controller 33 adjusts the distance d2 between the lens 21a of the camera module 21 and the image sensor 21b, analyzes the image signal from the camera module 21 at each distance, and The camera module 21 obtains the distance d2 between the lens 21a and the image sensor 21b having an optimal focus, and the driving device (the camera 21) has the distance between the lens 21a and the image sensor 21b. 34). The control unit 33 may include a digital signal processor (DSP) and a motor driver IC (Motor Driver IC).

4 is a flowchart for autofocusing of a camera module according to the present invention.

As shown in FIG. 4, when the start signal of the focus adjustment operation is input by a switch or the like, autofocusing is started. First, the lens position of the camera module is initialized (S410). Next, an image signal of a test chart photographed by the camera module is acquired (S420), a luminance signal is extracted from a predetermined region from the obtained image signal (S430), and the luminance signal is passed through a high pass filter (HPF). After extracting the contour component of the region (S440), the contour component is integrated, and the integrated value is squared to obtain an autofocus value (S450). Subsequently, it is checked whether the maximum autofocus value is found (S460), and when the maximum autofocus value is found (S460-Y), the lens of the camera module is moved to a position where the autofocus value is maximum (S480) and the focusing operation is performed. Quit. If the maximum autofocus value is not found (S460-N), the process of obtaining the autofocus value is repeated by adjusting the lens position of the camera module (S470). Through the above process, the focus of the camera module can be adjusted. In one embodiment of the present invention, the area for obtaining the autofocus value may be a plurality of areas for more accurate focus adjustment.

The present invention is not limited by the above-described embodiment and the accompanying drawings, but by the appended claims. Therefore, it will be apparent to those skilled in the art that various forms of substitution, modification, and alteration are possible without departing from the technical spirit of the present invention described in the claims, and the appended claims. Will belong to the technical spirit described in.

As described above, according to the present invention, by placing the projector between the test chart and the camera module to reduce the distance between the test chart and the camera module to be able to adjust the focus in a narrow workspace, and to adjust the lens distance of the projector This provides a focus adjuster that can adjust the focus of different types of camera modules together.

In addition, according to the present invention, the focus of the camera module is automatically adjusted by the autofocusing method of the camera module, thereby minimizing the occurrence of defects by reducing the deviation between operators by manual adjustment.

Claims (9)

In the camera module focusing device for adjusting the focus of the camera module having a lens and an image sensor, A test chart having a test pattern used to adjust the focus of the camera module; A projector positioned between the test chart and the camera module, the projector having a relay lens for enlarging and providing a test pattern of the test chart to the camera module; A focus adjuster connected to the camera module to adjust the position of the lens to optimize the image of the enlarged test pattern detected by the image sensor Camera module focusing device comprising a. delete The method of claim 1, And the projector can change an enlargement ratio according to the type and resolution of the camera module. The method of claim 1, And a light panel for irradiating light to the test chart and allowing a test pattern image transmitted through the test chart by the light to be directed toward the projector and the camera module. Device. The method of claim 1, The lens and the image sensor are screwed together, And the focus adjuster mechanically rotates the lens to adjust the focus of the camera module by adjusting a distance between the lens and the image sensor. The method of claim 5, A driving device for rotating the focus adjuster; A switch for generating a start signal of a focusing operation of the camera module; And Adjust the distance between the lens of the camera module and the image sensor, and analyze the image signal from the camera module at each distance to obtain the distance between the lens and the image sensor having the optimum focus of the camera module, the lens And a control unit for controlling the driving device such that the image sensor has the distance. Camera module focusing device further comprising a. The method of claim 6, And the driving device includes a DC step motor. a) photographing, by the camera module, the test pattern to obtain an image signal of the photographed test pattern; b) extracting a luminance signal from a predetermined region of the obtained image signal, extracting the contour component of the predetermined region by passing the luminance signal through a high pass filter, and integrating the contour component Obtaining an autofocus value by squaring; And c) changing the distance between the lens of the camera module and the image sensor and repeating steps a) and b) until the autofocus value has a preset maximum value; Camera module auto focusing method comprising a. The method of claim 8, And a predetermined area of the acquired video signal is a plurality of areas.

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