KR20090089192A - System and method for automatic visual inspection - Google Patents

Abstract

A system and a method for automatically checking an image are provided to automatically adjust an angle and a camera and a lighting, thereby reducing unnecessary costs and waste of time. An image checking device(120) photographs an image. A control device(110) automatically adjusts angles of a camera and a lighting by controlling the image checking device. An image receiving unit(111) transmits the received image to an image processing unit(112) after receiving the photographed image. The image processing unit extracts frequency components and edge components by analyzing the photographed image. Quality is checked by using the extracted component.

Description

Automatic image inspection system and automatic image inspection method in the system {SYSTEM AND METHOD FOR AUTOMATIC VISUAL INSPECTION}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic image inspection system and method, and more particularly, to automatically adjust the angle of a camera and lighting to accurately inspect defects on the surface or inside of a semiconductor substrate or other components during semiconductor or LCD production. An image inspection system and an automatic image inspection method therefor.

In the field of producing semiconductors or LCDs, the final product is completed by a number of granular processes. Thus, defects in components such as semiconductor substrates in the production process can cause serious problems that require the disposal of the finished product later. In order to solve this problem, inspection equipment for detecting defects in semiconductor substrates and components at a suitable time is required.

In general, to inspect semiconductors, equipment such as a high resolution digital camera or a line scan camera of the same principle as a scanner is mainly used. In particular, the line scan camera is widely used because it is advantageous for acquiring an ultra high resolution image.

However, when a digital camera or a line scan camera is used, various images are acquired according to a distance and an angle formed between the camera and the lighting device with a subject to be inspected, and a result of a test differs depending on the acquired image. Therefore, the distance and angle of the most appropriate camera and the distance and angle of the lighting device for each inspection subject should be found through a test.

Referring to the general inspection equipment for calculating the optimal conditions for the subject through such a test is as follows.

1 is a diagram illustrating an example of inspection equipment for calculating an optimal condition for each conventional subject.

As shown in FIG. 1, the subject is positioned at a location 30 where the optical axis of the camera 10 meets the optical axis of the lighting apparatus, the camera 10 is mounted at a position perpendicular to the subject, and the lighting apparatus ( The optical axis of the lighting device 21 is moved up and down so that the optical axis of the lighting device 21 is directed toward the subject while the supporting shaft 20 supporting the 21 is moved in the horizontal direction to calculate the distance and angle of the most suitable lighting device.

The existing inspection equipment such as the tester manually adjusts the position and angle of the lighting device 21 at the position where the camera 10 is fixed, and the tester manually changes the angle and distance of the camera 10. Set your location. At this time, there is a need to manually adjust the lighting device 21 again. This manual adjustment method requires a lot of time and effort, and it is difficult to keep the test results consistent.

In addition, if the inspection equipment is designed and manufactured without calculating the optimal installation conditions of the camera and the lighting device, additional cost and time must be wasted after completing the inspection equipment to find the optimal distance and angle between the camera and the lighting device. There is a problem.

In order to solve the problems described above, the present invention provides an automatic image inspection system and its system for automatically calculating the optimal condition by automatically adjusting the distance and angle of the camera and the lighting device mounted on the inspection equipment according to the type of subject to be inspected. It provides an automatic image inspection method in.

In addition, the present invention provides an automatic image inspection system for directly inspecting a subject under an optimal condition calculated by minimizing errors and automatically adjusting distance and angle precisely, and an automatic image inspection method in the system.

In addition, the present invention is an automatic image for minimizing the vibration transmission, which is a weak point of the variable equipment that can be conveniently adjusted without changing the focus even if the focal point for image acquisition adjusts the angle and distance of the camera and lighting. An inspection system and an automatic image inspection method in the system are provided.

The automatic image inspection system for achieving the above objects of the present invention, the image inspection apparatus for automatically adjusting the angle of the camera and the illumination is installed, the optical axis is matched to a specific point, to take an image; And controlling the image inspection apparatus to automatically adjust angles of the camera and the illumination, and to check the quality by analyzing the image photographed by the image inspection apparatus.

A method for achieving the objects of the present invention, an automatic image inspection system having an image inspection apparatus for photographing an image having a camera and illumination installed in accordance with a specific optical axis, and a control device for controlling the image inspection apparatus A method of automatically monitoring an image, the method comprising: adjusting an angle of the camera according to a control signal generated from the control apparatus to the image inspection apparatus; Adjusting an angle of the illumination according to a control signal generated by the image inspection device by the control device; Photographing an image of a subject in the image inspection device; Receiving the photographed image from the control device and inspecting the quality of the received image; And storing a result of the quality check of the image.

Therefore, the present invention can fix the focus (optical axis) of the camera and the light, and can automatically adjust the angle of the camera and the light according to the control of the control device to reduce unnecessary cost and waste of time, thereby reducing the vibration when shooting the image The occurrence and delivery can be minimized.

 In addition, the configuration of the rectangular coordinates and the tilt axis of the industrial robot requires three axes of horizontal, vertical and tilt (Tilt), but the present invention can reduce the cost because it can be composed of only two axes in the angle and distance, In high-precision systems, the more degrees of freedom, such as the number of axes and joints, the higher the precision in terms of less precision.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In describing the present invention, if it is determined that detailed descriptions of related known functions or configurations may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. In addition, the same reference numerals are used for parts having similar functions and functions throughout the drawings.

In the embodiment of the present invention will be described by applying an automatic image inspection system for acquiring and analyzing an image with a precision of less than 1 micrometer, the automatic image inspection system is to focus the camera when shooting by the camera and lighting You should also focus the lighting on the dark spots to get the best image. In order to adjust the distance and angle of the camera and lighting, a precise industrial robot is used, which has a configuration of a Cartesian coordinate system, and when the angle of the camera and lighting is modified, the position of the focus must be corrected in the X and Y axes. You can shoot without changing. In addition, it may use backlighting if necessary for the acquisition of the image.

The basic principle for the automatic image inspection according to an embodiment of the present invention is to adjust the focus of the camera even when the angle and position of the camera and the lighting device are changed after the subject is positioned at the point where the optical axis of the camera and the optical axis of the lighting device meet. The optical axis of the lighting device continues to face the subject.

Next, an automatic image inspection system according to an embodiment of the present invention using a precise industrial robot will be described in detail with reference to the accompanying drawings.

2 is a diagram illustrating a structure of an automatic image inspection system according to an exemplary embodiment of the present invention.

Referring to FIG. 2, the automatic image inspection system may be largely divided into a control apparatus 110 such as a computer and an image inspection apparatus 120.

The control device 110 may include an image receiver 111, an image processor 112, and a device controller 113, and the image inspection device 120 may include a driver 121, a camera 122, and an illumination ( 123). The detailed structure of the image inspection apparatus is shown in FIG. 3.

The image receiving unit 111 receives an image captured by the camera 122 and transmits the image to the image processing unit 122, and the image processing unit 112 analyzes the captured image to analyze a frequency component and an edge component. Extract and use the extracted ingredients to check quality. The device controller 113 controls a control signal for adjusting the angles of the camera 122 and the lighting 123 so as to inspect the image again when the image quality analyzed by the image processor 112 does not meet a preset reference value. Transmission to the drive unit 121. That is, the driving unit 121 is controlled to automatically adjust the angle by moving the camera 122 and the lighting 123.

The driving unit 121 is connected to the camera 122 and the lighting 123 and are devices Q1, Q2, Q3 and Q4 for moving the camera 122 and the lighting 123, and are precise industrial robots. Can be. Among the devices of the driving unit 121, Q2 and Q3 are rotating bodies 211 and 212 rotating around a specific point 201, and the camera 122 and the lighting 123 are rotated by the rotating body ( Connecting means 221 and 222 connected to 211 and 212 to move up and down and left and right, moving means 231 and 232 moving along an upper surface of the worktable 250, and one end of the moving means 231, It is connected to the 232 and the other end may be composed of the support (241, 242) fixed to the rotating body (211, 212). Q1 and Q4 of the devices of the driving unit 121 are devices corresponding to the work table 250. One end of each of the supports 241 and 242 coincides with the specific point, the other point is formed on the work table side, and the other end is fixed to the rotors 211 and 212 to form a triangular structure. This is controlled by the angle calculated by the trigonometric function.

The camera 122 may be variously applied to a high resolution digital camera, a line scan camera, or an area camera. The camera 122 is installed on the sample plate moving from side to side when the surface of the inspected object in the form of a high film is installed to match the central axis, that is, the specific point 201, the driving unit 121 with the central axis at this point as the focal point. It is installed on the rotating body 210 of.

The illumination 123 is installed on the rotating body 212 so that the optical axis coincides with the camera 122 focusing on the central axis, that is, facing the specific point 201, and is connected to the rotating body 212. As the rotor 212 rotates by the moving means 232 for moving the support 242, the angle and the distance are changed.

Then, the automatic image inspection method in the automatic image inspection system having such a structure will be described in detail.

Equipment such as line scan cameras have different characteristics in terms of the angle at which the camera looks at the object or the angle at which the light looks at the object. Therefore, image inspection must be automated in order to bring it into a relevant environment.

Therefore, it is necessary to match the camera and lighting to one point, adjust the camera and lighting at various angles, and adjust the camera's angle automatically until the experimenter obtains the desired result by taking an image. It will be described in detail with reference to the accompanying drawings.

4 is a view showing an operation for automatically adjusting the angle of the camera in the automatic image inspection system according to an embodiment of the present invention.

First, the surface of the inspected object in the form of a high film is placed on the sample plate moving from side to side, and the optical axis of the camera 122 and the illumination 123 are installed to coincide with the central axis. Then, the control device 120 of the automatic image inspection system controls the driving unit 121 to move the installed camera 122 and the illumination 123.

2 to 4, the control device 120 initializes the camera and the lighting in step 300, and then checks whether to convert the angle of the camera 122 in step 301. As a result of the check, when the angle of the camera 122 is not converted, the control device 120 performs step 307. Otherwise, in step 302, the control device 120 moves the camera 122 to the driving unit 121. By generating a control signal for converting the angle of the camera 122 to adjust the angle. That is, as shown in FIG. 3, the driving unit 121 moves the moving stage 231 moving along the upper surface of the work table 250 according to the control signal, thereby rotating the body 211 on which the camera 122 is mounted. Rotate) around the central axis. As the rotating body 211 is rotated as described above, the angle of the connected camera 122 is changed, and the focus continues toward the central axis.

Next, in step 303, the control device 120 determines whether to change the angle of the lighting 123. As a result of the check, if not converted, the control device 120 performs step 307. Otherwise, in step 304, the control device 120 transmits a control signal to the driver 121 to adjust the angle of the lighting 123. do. That is, as shown in FIG. 3, the driving unit 121 moves the moving means 232 moving along the upper surface of the work table 250 according to the control signal, and the rotating body 212 on which the lighting 123 is mounted. Rotate around the central axis. As the rotating body 212 is rotated as described above, the angle of the connected camera 122 is changed, and the focus continues toward the central axis.

When the angle of the camera 122 and the lighting 123 is adjusted in this way, the camera 122 transmits the captured image to the control device 120 by photographing the installed film.

Accordingly, in step 305, the control device 120 receives and stores the captured image from the camera 122, and then checks whether to capture an image further in step 306. Repeat the process afterwards.

On the other hand, if the additional photographing is not performed, the control device 120 checks the quality of the stored photographed images in step 307, checks whether the retest is checked in step 308, and then proceeds to step 301 again after rechecking the operation. If not, in step 309, the control device 120 stores the image quality inspection result and ends the operation. In step 307, quality inspection of the captured images is performed by using a component extracted by extracting a frequency component and an edge component.

As described in the above operation, when the rotating body 211 is rotated by moving the moving means 231 connected to the rotating body 211 of the camera 122, the focal length of the camera 122 is changed. The support 241 installed in the Q2 is a triangular structure consisting of a fixed point of Q1 coinciding with the central axis, a fixed point of an intermediate point in the Q2, and a point fixed to the upper end of the conveying means 231 of Q1. This can be controlled by the angle calculated by the trigonometric function. Despite the change in angle and distance of the camera 122, the optical axis does not deviate from the central axis.

When the precision of Q1 is 1/100 mm, the angle precision can be controlled to about 0.00_ degrees. In addition, in the structure of industrial robots such as Q1 to Q4, the ball screw is used. Inevitably an error occurs due to the backlash caused by the bearing tolerance, but in the triangular structure as described above, even in a position where 90 degrees is maintained The weight is distributed to the horizontal axis by the triangular structure, and the force is applied outward of the Q1 axis. In other words, the backlash disappears on the horizontal axis, just as the backlash becomes zero on the robot placed on the vertical axis. Therefore, the angle and distance of the image inspection apparatus can be precisely controlled without error. And the triangle, that is, each vertex of the support (241, 242) is composed of a bearing and a shaft because it must be rotatable, the axis of each vertex has a fixed clamping device by pneumatic as shown in Figure 3, the transfer is completed It is possible to minimize the generation and transmission of vibration during post-image capture.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by the equivalents of the claims.

1 is a view showing an example of inspection equipment for calculating the optimal conditions for each conventional subject;

2 is a diagram showing the structure of an automatic image inspection system according to an embodiment of the present invention;

3 is a diagram illustrating a detailed structure of an image sensing device of an automatic image inspection system according to an exemplary embodiment of the present invention;

4 is a view showing an operation for automatically adjusting the angle of the camera in the automatic image inspection system according to an embodiment of the present invention.

Claims (12)

An image inspection device that automatically adjusts an angle of a camera and lighting installed by matching an optical axis to a specific point, and captures an image; And And a control device that controls the image inspection device to automatically adjust angles of the camera and the illumination, and checks the quality by analyzing the image photographed by the image inspection device. The image inspection apparatus of claim 1, The camera is installed so that the optical axis is directed to the specific point, the angle is adjusted according to the control signal from the control device to take an image; The illumination is installed in correspondence with the optical axis of the camera and the specific point, the illumination is adjusted in accordance with the control signal; And And a driving unit connected to the camera and the illumination to adjust angles of the camera and the illumination according to the control signal. The method of claim 2, wherein the driving unit, A work bench on which an inspection object is located; A rotating body mounted to the camera such that an optical axis coincides with the specific point, and rotating based on the specific point; A support for supporting the rotating body; And A moving means connected to one end of the support and moving on the worktable, And the rotating body rotates in response to the control signal to automatically adjust an angle of the camera mounted on the rotating body. The method of claim 2, wherein the driving unit, A work bench on which an inspection object is located; A rotating body mounted with the illumination such that an optical axis coincides with the specific point, and rotating based on the specific point; A support for supporting the rotating body; And A moving means connected to one end of the support and moving on the worktable, And the rotating body rotates in response to the control signal to automatically adjust the angle of the illumination mounted to the rotating body. The method according to claim 3 or 4, The support is characterized in that one point of one end is matched to the specific point, the other point is formed on the workbench side, the other end is fixed to the rotating body is formed in a triangular structure is controlled at an angle calculated by the trigonometric function Automatic video inspection system. The method of claim 1, wherein the control device, An image receiving unit receiving an image captured by the image inspection device; An image processor which analyzes and stores the quality of the image received through the image receiver; And And an apparatus controller for generating a control signal for controlling the image inspection apparatus according to a result of the quality analysis of the image. The method of claim 6, And the image processor extracts a frequency component and an edge component from the received image and inspects the quality of the received image using the extracted component. In an automatic image inspection system having an image inspection apparatus for photographing an image having a camera and illumination installed by matching an optical axis to a specific point, and a control device for controlling the image inspection apparatus, the method for automatically monitoring the image, Adjusting an angle of the camera according to a control signal generated by the image inspecting device from the control device; Adjusting an angle of the illumination according to a control signal generated by the image inspection device by the control device; Photographing an image of a subject in the image inspection device; Receiving the photographed image from the control device and inspecting the quality of the received image; And And storing the result according to the quality inspection of the image. The method of claim 8, Generating a control signal to the image inspection apparatus again to re-inspect the image of the subject when the result of the quality inspection of the image does not reach a predetermined reference value by the control apparatus. An automatic video surveillance method in an automatic video inspection system. The method of claim 8, The adjusting of the angle of the camera may include automatically adjusting the angle of the camera by operating the driving unit of the video surveillance apparatus according to the control signal to rotate the rotating body of the driving unit on which the camera is mounted. Automated Video Surveillance in Automated Video Inspection Systems. The method of claim 8, The adjusting of the angle of the illumination may include automatically adjusting the angle of the illumination by operating the driving unit of the video surveillance apparatus according to the control signal to rotate the rotating body of the driving unit equipped with the illumination. Automated Video Surveillance in Automated Video Inspection Systems. The method of claim 8, wherein the checking of the quality of the received image comprises: Extracting a frequency component by analyzing the received image; Extracting an edge component by analyzing the received image; And And inspecting the quality of the received image by using the extracted frequency component and the edge component.

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