KR101338339B1 - Lens module inspection machine - Google Patents

Abstract

An apparatus for inspecting a lens module according to an embodiment of the present invention comprises: a handler for placing a lens module on a lens mounting or removing the lens module; an image sensor which is positioned apart from and faces the lens module placed on the lens mounting by the handler and obtains a chart image related to the lens module inspection by moving a long distance or short distance towards the lens module; a header board which is positioned on the bottom of the image sensor and transfers the chart image obtained by the image sensor to a capture board; a support for horizontally supporting the header board to adjust the horizontal between the image sensor and the lens module; and an actuator which is positioned on the bottom of the support, and raises and lowers the support according to the operation of a step motor. [Reference numerals] (130) Capture board

Description

Lens module inspection device {LENS MODULE INSPECTION MACHINE}

Embodiments of the present invention relate to a lens module inspection apparatus.

Currently, mobile phones or PDAs are being designed to have a photographic or video capturing function. Accordingly, demand for small camera modules included in such devices and demands for improving functions are steadily increasing.

The lens module included in such a small camera module generally has a form in which a plurality of lenses are stacked in one barrel.

In general, in the lens module, the diameter of the lenses is formed to be slightly larger than the diameter of the inside of the barrel, so that the lenses are tightly fitted in the barrel to be fixed at the same time as assembly.

However, due to an unexpected error such as external impact, foreign matter inflow, malfunction of assembly equipment, and the like, the lenses may not be assembled normally and may be disposed obliquely to the optical axis.

On the other hand, the prior art related to the present invention is registered Patent Publication No. 10-1021691 (name of the invention: lens inspection device, registration date: March 4, 2011).

One embodiment of the present invention can perform the automatic determination of the failure of the lens module, thereby providing a lens module inspection apparatus that can improve the inspection efficiency of the lens module.

The problems to be solved by the present invention are not limited to the above-mentioned problem (s), and another problem (s) not mentioned can be clearly understood by those skilled in the art from the following description.

An apparatus for inspecting a lens module according to an embodiment of the present invention includes a handler for placing a lens module on a lens mount or removing the lens module from the lens mount; An image sensor spaced apart from the lens module mounted on the lens mount by the handler and acquiring a chart image related to the inspection of the lens module through near and far movements to the lens module; A header board disposed under the image sensor and transferring the chart image acquired by the image sensor to a capture board; A support for horizontally supporting the header board to adjust the horizontality between the image sensor and the lens module; And an actuator disposed below the support and configured to raise and lower the support according to the driving of the stepper motor.

The lens module inspection apparatus according to an exemplary embodiment of the present invention may further include a capture board for capturing the chart image transmitted by the header board and transmitting the captured image to the PC.

The lens module inspection apparatus according to an exemplary embodiment may further include first and second distance detection sensors for detecting a position of the image sensor and adjusting a moving distance of the image sensor.

The support may include a horizontal adjustment device for horizontal adjustment of the support.

The chart includes a pattern in which a plurality of black lines are gradually narrowed, and the lens module inspection apparatus scans from the left and right sides of the chart to the center and obtains a vertical line average brightness, and then sets a difference in the average value from the previous vertical line. If it is larger, it is recognized as the start point or the end point of the chart and is displayed as a vertical black line, and after calculating the distance between the start point and the end point indicated by the black line, The resolution difference value of 1 pixel can be obtained.

The lens module inspection apparatus calculates an input contrast value by comparing the brightness values of the black lines constituting the chart with the white lines of the background while scanning from the position of the maximum value found in the region of the chart to the position of the minimum value, We can find the point where the contrast value with the neighboring black line satisfies all the reference values.

The lens module inspection apparatus may calculate a resolution value by obtaining a pixel distance between a position at which a minimum value and a contrast value are satisfied, multiplying the resolution value per pixel, and adding the minimum value to the minimum value.

When the lens module inspection apparatus inspects the lens module, the lens module inspection apparatus obtains a distance value of a cross-shaped pattern in the center of the chart, and when the distance value decreases, toward the center, and when the distance value increases, a diagonal direction By moving to, the region of interest (ROI) region representing the inspection region in the chart can be corrected to match the position of the chart.

The lens module inspection apparatus may calculate a modulation transfer function (MTF) using the brightest and darkest values in the ROI region representing the inspection region in the chart.

The PC may determine whether the lens module is unsuccessful using some frames of the chart image transmitted by the capture board.

The details of other embodiments are included in the detailed description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and / or features of the present invention, and how to accomplish them, will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but is capable of many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

According to one embodiment of the present invention, it is possible to perform the automatic determination of the failure of the lens module, thereby improving the inspection efficiency of the lens module.

1 is a view illustrating a lens module inspection apparatus according to an exemplary embodiment of the present invention.
FIG. 2 is a diagram illustrating a screen of an inspection program for performing a fail determination of a lens module according to an exemplary embodiment of the present invention.
3 illustrates an example of correcting a position of an ROI region of a chart according to an exemplary embodiment of the present invention.
4 is a diagram illustrating an example of a pattern of a chart applied to an embodiment of the present invention.
5 is a view showing a state when inspecting a chart according to an embodiment of the present invention.
6 and 7 illustrate a method of calculating an MTF according to an embodiment of the present invention.
FIG. 8 is a diagram illustrating a method of determining whether a lens is defective or not in a lens module according to an exemplary embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view illustrating a lens module inspection apparatus according to an exemplary embodiment of the present invention.

Referring to FIG. 1, the lens module inspection apparatus 100 according to an exemplary embodiment may include a handler 105, an image sensor 110, a header board 120, a capture board 130, a PC 140, It may be configured to include a support 150, the actuator 160, and the first to third distance sensing sensors 170, 180, 190.

The handler 105 functions to place the lens module 101 on the lens mount 102 or to remove the lens module 101 from the lens mount 102. The handler 105 may be implemented as a robot arm, and thus may fully automate the inspection of the lens module 101.

The image sensor 110 is spaced apart from the lens module 101 mounted on the lens mount 102 by the handler 105. That is, the image sensor 110 forms a structure in which the lens module 101 faces each other at a predetermined distance therebetween, and a chart 103 for inspecting the lens module 101 on the lens module 101. Are spaced apart from each other.

In this case, the lens module 101 is mounted on the lens mount 102 by the handler 105 and maintained in a fixed state. The lens module 101 is automatically removed by the handler 105 after the inspection is completed. In addition, the chart 103 has patterns used for the inspection of the lens module 101 and may include patterns having a shape in which a plurality of black lines are gradually narrowed.

The image sensor 110 acquires an image of the chart 103 viewed through the lens module 101 through near and far movements to the lens module 101. That is, the image sensor 110 acquires an image of the chart 103 while approaching the lens module 101 in close forward direction as the actuator 160 is driven, and then moves far in the reverse direction. An image of the chart 103 is obtained.

In this case, the image sensor 110 may have a maximum movement distance d1 and an effective movement distance d2 according to the driving of the actuator 160. In one embodiment of the present invention, the maximum travel distance (d1) is 0.6mm, the effective travel distance (d2) may be 0.3mm.

The header board 120 is disposed under the image sensor 110. The header board 120 connects the image sensor 110 and the capture board 130.

Meanwhile, when the image sensor is to be replaced, the conventional lens module inspection apparatus has to replace the entire module equipped with the image sensor. However, the lens module inspection apparatus according to the present invention has an advantage in that only the header board 120 on which the image sensor 110 is mounted is removed and replaced when the image sensor 110 is to be replaced.

In addition, the header board 120 also serves to transfer the image of the chart 103 acquired by the image sensor to the capture board 130.

The capture board 130 captures an image of the chart 130 transmitted by the header board 120, and transfers the captured chart 130 image to the PC 140.

The PC 140 determines whether the lens is defective by using the image received from the capture board 130. In the present invention, the PC 140 may use only some of the frames of the chart 130 image transmitted from the capture board 130 to determine whether the lens is defective. For example, the PC 140 discards the first frame of the four frames of the chart 130 image transmitted from the capture board 130 and performs a good or bad judgment of the lens using only the remaining three frames. The PC 140 may communicate with the capture board 130 through wired / wireless communication, for example, in a standard manner such as USB, Camera Link, Bluetooth, and Wi-Fi.

In order to determine whether the lens module 101 is defective, the PC 140 may be equipped with a program for inspecting the lens module 101, and by performing the determination of the failure of the lens module 101 through the program. As shown in FIG. 2, the screen may be displayed on the screen. For reference, FIG. 2 is a diagram illustrating a screen of an inspection program for performing a fail judgment of the lens module 101 according to an exemplary embodiment of the present invention.

The support 150 serves to horizontally support the header board 120 in order to adjust the horizontality between the image sensor 110 and the lens module 101. To this end, the support 150 may be disposed below the header board 120.

In addition, the support 150 may be provided with a horizontal adjustment device 152 for the horizontal adjustment of the support 150. The horizontal adjustment device 152 adjusts the X-axis and Y-axis horizontality of the support 150. In another embodiment of the present invention, the horizontal adjustment device 152 may be composed of a first horizontal adjustment device for adjusting the X axis of the support 150 and a second horizontal adjustment device for adjusting the Y axis of the support 150. have.

The actuator 160 is disposed below the support 150. The actuator 160 may include a step motor 162 and a cylinder 164. The actuator 160 may raise and lower the image sensor 110 by operating the cylinder 164 according to the driving of the step motor 162 to raise and lower the support 150.

In one embodiment of the present invention, the support 150 is lifted up and down within a certain range by the actuator 160, so that the image sensor 110 on the header board 120 is raised and lowered. In the lens module inspection apparatus according to the related art, the capture board connected to the support is lifted together by lifting the support to move the image sensor, but in the present invention, only the support 150 is lifted up and down to lift the image sensor 110. The capture board 130 has an advantage of not moving.

As a result, in the present invention, the focal length between the image sensor 110 and the lens module 101 can be adjusted by driving the actuator 160 to raise and lower the support 150.

The first to third distance detecting sensors 170, 180, and 190 may detect a position of the image sensor 110 to adjust a moving distance of the image sensor 110.

The first distance sensor 170 may detect a limit position of a short distance at the maximum travel distance d1, and the second distance sensor 180 may detect a far distance at the maximum travel distance d1. The limit position can be detected.

In addition, the third distance sensor 190 may detect a limit position of a far distance at the effective travel distance d2, and substantially when the image sensor 110 inspects the lens module 101. You can detect where you start or stop. That is, the third distance sensor 190 may detect the position of the motor home for the far-near-far inspection.

The lens module inspection apparatus 100 may provide a function of correcting a position of a region of interest (ROI) region representing an inspection region in the chart. The reason for correcting the ROI position is as follows.

When the lens module 101 is inspected, the inspection screen is zoomed in or zoomed out by changing the distance between the image sensor 110 and the lens module 101. Since the position of the chart changes, the ROI area should also be corrected to match the position of the chart.

To this end, the lens module inspection apparatus 100 obtains the distance value of the cross-shaped pattern 310 in the center of the chart, as shown in FIG. 3, when the lens module 101 is inspected. If the distance value decreases, the distance value may move toward the center, and if the distance value increases, the distance value may move toward the outer side.

At this time, when moving to the center side or the outer side may move in the diagonal direction. As a result, the lens module inspection apparatus 100 may correct a region of interest (ROI) region representing an inspection region in the chart so as to match the position of the chart. For reference, FIG. 3 illustrates an example of correcting a position of an ROI region of a chart according to an embodiment of the present invention.

On the other hand, as described above, the pattern included in the chart 103 has a form in which several black lines are gradually narrowed, as shown in FIG. For reference, FIG. 4 is a diagram illustrating an example of a pattern of a chart applied to an embodiment of the present invention. Hereinafter, with reference to FIG. 5 showing a state of inspecting the chart, chart region detection and resolution ( Resolution) Inspection, calculation of resolution value, etc. will be described.

1. Chart area detection

1) Scan from the left and right side of the ROI area to the center and find the average brightness of the vertical line. If the difference between the average value and the previous vertical line is greater than the set value, it is recognized as the start or end point of the chart and displayed as a black line.

2) Obtain the distance (Pixel) between the start point and the end point of the chart, and find the resolution difference value of 1 pixel using the minimum and maximum values.

Ex) Min = 900, Max = 2000, chart distance = 200 Pixel

1 Pixel Resolution Difference = (Max-Min) / Chart Distance

Resolution difference of 1 Pixel = (2000-900) / 200 = 5.5

2. Resolution inspection

1) Compare the brightness value of black line and white line (desktop) while scanning with Min value position from the Max value position found in the chart area, and calculate the entered contrast value. Find a point that satisfies everyone.

Calculate the Contrast value = ((White line brightness value-Black line brightness value) / (White line brightness value + Black line brightness value)) * 100

3.Calculate Resolution Value

1) Calculate the pixel distance at the point where the Min value and Contrast value are satisfied and multiply the resolution value per pixel and add it to the Min value.

Ex) Min = 900, Distance from Min position = 164, Resolution difference of Pixel = 5.5

Resolution value = 900 + (164 * 5.5) = 1807.5

6 and 7 illustrate a method of calculating a Modulation Transfer Function (MTF) according to an embodiment of the present invention.

First, in order to calculate the MTF, a chart having the same pattern shape as shown in FIG. 6 is required. The lens module inspection apparatus 100 may calculate the MTF using the brightest and darkest values in the ROI region representing the inspection region in the chart of FIG. 6. The calculation result of the MTF is Good Focus when the MTF is 71 as shown in FIG. 7, but Bad Focus when the MTF is 9.

The calculation formula of the MFT is as follows.

MTF = ((bright-dark) / (bright + dark)) * 100

Example 1) ((200-33) / (200 + 33)) * 100 = 71

Example 2) ((60-50) / (60 + 50)) * 100 = 9

Hereinafter, a method of determining whether a lens is good or bad of a lens module according to an embodiment of the present invention will be described in detail with reference to FIG. 8. For reference, FIG. 8 is a diagram illustrating a method of determining whether a lens is defective or not in a lens module according to an exemplary embodiment of the present invention.

1. The position of the image sensor 110 is changed by operating the step motor 162 of the actuator 160 at a distance from a short distance.

2. The best measured after stopping the operation of the step motor 162 at the position (b) where the preset value is obtained by calculating the resolution value from the image of the chart 103 received as the position of the image sensor 110 is raised. Calculate position (Best Positon).

3. The step motor 162 is moved to the initial position (c) of the near-field payment determination away from the calculated Best Position position by a constant pulse.

4. After stopping the step motor 162, the image is received from the capture board 130, the first frame is discarded, and three more frames are received to determine whether the lens is poor.

5. Move the position of the image sensor 110 by one step to the distance and repeat the process four times. (d, e, f, g)

6. After making a total of five determinations, the final determination is made and the image sensor 110 is moved to the far position (a).

In the embodiment of FIG. 8, the lens module is inspected through five determinations at five points, but the number of measurement points and the number of measurement points may vary according to embodiments.

The lens module inspection apparatus 100 according to an embodiment of the present invention is designed to easily and conveniently modify the ROI position adjustment or the ROI setting value of the inspection chart when inspecting the lens module in the administrator mode, and various inspections. It is developed to make it easy for administrators to set optimal inspection conditions while inputting and changing elements. Therefore, according to an embodiment of the present invention, it is possible to perform the automatic determination of the failure of the lens module, and through this, it is possible to quickly and accurately inspect the lens module.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by the scope of the appended claims and equivalents thereof.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, Modification is possible. Accordingly, the spirit of the present invention should be understood only in accordance with the following claims, and all equivalents or equivalent variations thereof are included in the scope of the present invention.

101: lens module
102: lens mount
103: chart
105: handler
110: image sensor
120: header board
130: capture board
140: PC
150: Support
152: leveling device
160: actuator
162: step motor
164: cylinder
170: first distance detection sensor
180: second distance detection sensor
190: third distance detection sensor

Claims (10)

A handler for placing a lens module on the lens mount or removing the lens module from the lens mount;
An image sensor spaced apart from the lens module mounted on the lens mount by the handler and acquiring a chart image related to the inspection of the lens module through near and far movements to the lens module;
A header board disposed under the image sensor and transferring the chart image acquired by the image sensor to a capture board;
A support for horizontally supporting the header board to adjust the horizontality between the image sensor and the lens module; And
An actuator disposed below the support and configured to raise and lower the support according to the driving of the step motor;
Lens module inspection apparatus comprising a.
The method of claim 1,
Capture board for capturing the chart image transmitted by the header board and transmitting to the PC (PC)
Lens module inspection apparatus, characterized in that it further comprises.
The method of claim 1,
First and second distance sensing sensors for adjusting the moving distance of the image sensor by sensing the position of the image sensor
Lens module inspection apparatus, characterized in that it further comprises.
The method of claim 1,
The support
Lens module inspection apparatus, characterized in that it comprises a leveling device for leveling the support.
The method of claim 1,
The chart is
A plurality of black lines include patterns of narrowing shape,
The lens module inspection device
After scanning from the left and right sides of the chart to the center and obtaining the average brightness of the vertical lines, if the average difference from the previous vertical lines is greater than the set value, it is recognized as the start point or the end point of the chart and displayed as a vertical black line. The lens module inspection apparatus of claim 1, wherein a resolution difference value of one pixel is obtained by using a minimum value (Min) and a maximum value (Max) input after obtaining a distance between a start point and an end point indicated by.
The method of claim 5,
The lens module inspection device
The contrast value is calculated by comparing the brightness values of the black lines forming the chart with the white lines of the background while moving from the position of the maximum value found in the region of the chart to the position of the minimum value. Lens module inspection apparatus, characterized in that for finding the point where the value satisfies all the reference value.
The method according to claim 6,
The lens module inspection device
And calculating a resolution value by multiplying a resolution value per pixel by calculating a pixel distance at a point at which a minimum position value and a contrast value are satisfied, and adding the minimum value to the minimum value.
The method of claim 1,
The lens module inspection device
When the lens module is inspected, the distance value of the cross-shaped pattern in the center of the chart is obtained, and when the distance value decreases, the distance is moved toward the center, and when the distance value increases, the chart is moved diagonally toward the outside. And correcting a region of interest (ROI) region indicating an inspection region to match the position of the chart.
The method of claim 1,
The lens module inspection device
And a MTF (Modulation Transfer Function) is calculated using the brightest and darkest values in the ROI region representing the inspection region in the chart.
3. The method of claim 2,
The PC is
And determining whether the lens module is unsuccessful using some frames of the chart image transmitted by the capture board.

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