KR100387197B1 - Apparatus and method for performing high speed vision inspection - Google Patents

Abstract

The novel defect detection system of the present invention comprises a CCD camera for receiving image data of a product to be detected a defect, preprocessing means for performing hardware preprocessing on image data input from the CCD camera, and preprocessing means. And a main processor for detecting a defective position of the product in response to the generated preprocessing result and for determining whether the product is defective or not. The system directly receives image data input through a CCD camera and processes the image data in hardware. The image data, which is represented in gray scale or color through bidirectional derivative and bidirectional dress operation, is binary data. ) Can significantly reduce the amount of data to be processed in the main processor.

Description

High speed defect detection system and method {APPARATUS AND METHOD FOR PERFORMING HIGH SPEED VISION INSPECTION}

The present invention relates to a defect inspection system, and more particularly to a defect inspection system capable of performing defect inspection in real time.

Digital image processing technology, which is a technology for processing images using a computer, has been an important research field since the 1960s. Since the 1970s, the remarkable advances in microprocessors have made it easier to use computers at a lower cost, and to drive the development of Factory Automation (FA). In particular, computer vision system using digital image processing technology is an artificial intelligence vision system that makes it possible to infer self with high intelligence from limited fields such as automatic inspection or assembly work in various production lines. Simplified, industrial vision systems have been developed and distributed in various ways, taking into consideration the reduction of processing time or the adaptability to changing objects.

A vision system for performing automated inspection on a production line is described in U.S. Pat. No. 5,078,496, "MACHINE VISION SURFACE CHARACTERIZATION SYSTEM", and U.S. Pat. No. 5,483,603, "SYSTEM AND METHOD FOR AUTOMATIC OPTICAL INSPECTION", and the like.

1 is a block diagram showing the structure of a defect detection system 1 according to the prior art. Referring to FIG. 1, a general defect detection system 10 may include a charge coupled device camera 1, which is an input device for receiving an image, and an image data input from the CCD camera 10. A frame grabber (2), which is an image capture board for converting the image data, and a computer (3), which is a main processor for processing and storing image data obtained by the image capture board (2).

Generally, in the defect detection system 1 which has such a structure, the analog or digital image data output to the CCD camera 1 is the data storage device of the computer 3 via the image capture board 2. For example, it is stored on a diskette or hard disk. The computer 3 reads the image data only after all of the image data is stored, and then performs image processing in software to derive the desired result.

Therefore, the conventional defect detection system 10 requires a time for performing an image capture operation on the image data input from the CCD camera 1, and a time for reading and processing the stored image data. In addition, the defect detection system 10 stores all the data input from the CCD camera on the computer 3 without processing the data, so that the computer 3 takes a lot of time when it is determined whether the product 3 is inspected. There is a problem. For example, research institutes such as schools and research institutes are not a problem because data processing time is not very limited, but the defect detection system applied to a production site is very important because the processing speed is very important. There is a speed limitation in processing images with the system 10. Therefore, there is a need for a new apparatus and method capable of performing preprocessing of images at a higher speed.

Accordingly, an object of the present invention is to provide a device and method capable of performing defect inspection in real time, which is proposed to solve the above-mentioned problems.

1 is a block diagram showing the structure of a defect detection system according to the prior art;

2 is a block diagram showing the structure of a defect detection system according to the present invention;

3 is a block diagram showing the structure of the preprocessing module shown in FIG. 2; And

4 is a flowchart showing the operation procedure of the defect detection system according to the present invention.

* Description of the symbols for the main parts of the drawings *

20: input module 21: CCD camera

22: CCD / light control unit 23: illumination

30: interface unit 31: A / D converter

32: synchronization signal generating circuit 40: preprocessing unit

41: bidirectional differentiator 42: bidirectional dresser

43: FIFO 50: Digital I / O

60: preprocessing module 70: main processor

According to one aspect of the present invention for achieving the object of the present invention as described above, a defect detection system for detecting a defect of a product comprises: a CCD camera for receiving image data of the product; Preprocessing means for performing hardware preprocessing on the image data input from the CCD camera; And a main processor for detecting a defect position of the product in response to a preprocessing result generated from the preprocessing means, and for determining whether the product is defective or not.

According to another aspect of the present invention for achieving the object of the present invention as described above, an operation method of a defect detection system for detecting a defect of a product comprises: receiving image data of the product; Performing bidirectional differential on the image data; Converting the differentiated data into binary data and determining a data propagation direction for the converted data; Determining whether the binary data is fed back in response to the determined data progress direction; Storing the data in data storage means when the binary data is not fed back; Transmitting the stored data to a main processor; And in response to the transmitted data, determining a defect location occurring in the product and whether the product is defective or not.

(Example)

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to FIGS. 2 to 4.

The novel defect detection system of the present invention directly receives image data input through a CCD camera and performs hardware preprocessing to shorten the preprocessing time of the image data. In addition, the amount of data is significantly reduced by converting image data expressed in gray scale or color into binary data through bidirectional differential and bidirectional threshold operations.

2 is a block diagram showing the structure of the defect detection system 100 according to the present invention, Figure 3 is a block diagram showing the structure of the preprocessing module shown in FIG. First, referring to FIG. 2, the defect detection system 100 according to the present invention is largely composed of an image input module 20, a preprocessing module 60, and a main processor 70. The image input module 20 includes a CCD camera 21, a CCD / light control unit 22, and a lighting unit 23.

The CCD camera 21 is used as an image data input device of the defect detection system 100, and the illumination 23 is used to make the projection data have an even brightness. Here, the CCD camera 21 may be configured as an analog or digital type CCD camera, and may be configured as a line scan camera that receives data in a line unit at a high resolution. And the CCD / light control unit 22 is used to control the operation of the CCD camera 21 and the illumination 23.

Here, the preprocessing module 60 is mainly composed of an interface unit 30, a preprocessing unit 40, and a digital input / output (I / O) 50, and logic such as a field programmable gate array (FPGA) or CPLD. It consists of hardware equipped with. The main processor 70 may be configured as a computer or a micro-computer on which a defect detection program is mounted.

Image data input through the image input module 20 having such a configuration is converted into digital image data and input to the preprocessing module 60. As will be described in detail later, the preprocessing module 60 directly receives digital image data without performing the conventional image capture board to perform hardware preprocessing. The preprocessing performed here is a bidirectional differential and bidirectional threshold operation, and has a characteristic of feeding back a result value that is previously performed so that it does not continuously affect the next data. When the derivative and the dressing process are performed, the amount of data is significantly reduced because image data expressed in gray scale or color is converted into binary data representing black and white. As described above, the preprocessing result is output to the main processor 70 via the digital I / O 50 provided in the preprocessing module 60.

Referring to FIG. 3, the interface unit 30 included in the preprocessing module 60 may include an A / D converter for converting the analog image signal DATA_A input from the CCD camera 21 into a digital image signal DATA_D. 31, the synchronization signal generation circuit 32 for generating the synchronization signal Sync with the CCD camera 21, and the digital image signal DATA_D generated from the A / D converter 31 are preprocessed in the unit 40. It includes a digital interface unit 33 for transmitting to.

Generally, CCD cameras are classified into standard cameras and nonstandard cameras, and each camera is classified into an analog CCD camera and a digital CCD camera. Since the data used for image processing is digital data, if the camera mounted on the system is a digital CCD camera, it can be used immediately without converting the data. However, when the camera mounted on the system is an analog camera, a device capable of converting analog data provided from the camera into digital data is required. Therefore, the interface unit 30 of the defect detection system 100 according to the present invention is A. FIG. / D converter 31 is included. The interface unit 30 of the defect detection system 100 according to the present invention is a synchronization signal for providing a synchronization signal Sync when the CCD camera 21 is a non-standard camera requiring a synchronization signal Sync. The generating circuit 32 is included.

When the image data DATA_A input through the image input module 20 is converted into the digital image data DATA_D through the A / D converter 31 and then input to the preprocessing unit 40 through the digital interface 33. The bidirectional differentiator 41 provided in the preprocessing unit 40 performs differentiation on the input digital video signal.

In particular, the edge portion of the image data input to the defect detection system 10 is a portion where the shade value changes abruptly, and the defect present in the object to be inspected is also a portion where the shade value rapidly changes. Thus, a derivative operation that takes a change in function can be used for defect detection. There are first derivatives (gradient) and second derivatives (Laplacian). The first derivative is explained as follows.

For example, when the coordinates of the pixels constituting the image data input to the defect detection system 100 are (x, y), the first order gradient representing the shade distribution is expressed by Equation 1 below. It is expressed as

G (x, y) = (fx, fy)

Here, fx represents the derivative in the x direction, fy represents the derivative in the y direction, and digital images of fx and fy are calculated as in Equations 2 and 3, respectively.

derivative in the x direction fx = f (x + 1, y)-f (x, y)

derivative in the y direction fy = f (x, y + 1)-f (x, y)

In order to take the horizontal derivative in extracting the contour, the horizontal differential algorithm as in Equation 4 or the vertical differential algorithm as in Equation 5 is used.

F (X, Y) = | F (X, Y-1)-F (X, Y + 1)

F (X, Y) = | F (X + 1, Y)-F (X-1, Y)

That is, when the derivative in the horizontal direction is based on any one point (F (X, Y)), the X coordinates are the same, and only the Y coordinate can be obtained by obtaining a difference value between pixels corresponding to the top and bottom of the center pixel. The derivative in the vertical direction is obtained by calculating the difference value between the pixels corresponding to the upper and lower sides of the center pixel while the Y coordinate is the same when one point (F (X, Y)) is referred to. .

The differential result DATA_D 'obtained by such an operation is inputted to the bidirectional dresser 42 to be converted into binary data DATA_B, and is coded according to the advancing direction of the data. For example, if this sign is positive, data advances forward and is input to a first input first output (FIFO) 43. If this sign is negative, it is fed back to the bidirectional differentiator (41). This bidirectional threshold operation is intended to prevent previous data from continuing to affect current or future data.

The binary image data DATA_B stored in the FIFO 43 is input to the main processor 70 via the digital I / O 50. A serial communicator is connected between the digital I / O 50 and the main processor 70 to exchange data regarding processing conditions between the main processor 70 and the preprocessor module 40.

4 is a flowchart illustrating an operation procedure of the defect detection system 100 according to the present invention. Referring to FIG. 4, in step S10, image data is received through an image input module 20 provided with a CCD camera 21 or the like. Subsequently, in step S12, bidirectional differentiation is performed through the bidirectional differentiator 41 provided in the preprocessing unit 40, and in step S14, the differential data transmitted from the bidirectional differentiator 41 is binary through the bidirectional dresser 42. Generate data (binary data) and determine the direction of data progress. In step S16, it is determined whether data is fed back according to the advancing direction of the data determined in step S14. As a result of the determination, if the data is fed back, the procedure returns to step S12. If the data is not fed back, the procedure goes to step S18. In step S18, the binary data converted by the bidirectional dresser 42 in step S14 is stored in the FIFO 43. In operation S20, the binary data is transmitted to the main processor 70 through the digital I / O 50. In step S22, the main processor 70 determines the position where the defect occurred in response to the binary data, and whether there is a defect of the object to be inspected, that is, whether the product is good or bad.

The defect detection system 100 according to the present invention which performs such an operation may directly input the digital image data input through the image input module 20 through the preprocessing unit 40 included in the preprocessing module 60. Accepts and performs hardware preprocessing. As a result, the processing time of the image data is shortened by storing the image data in the main processor through the image capture board and processing the existing preprocessing operation performed by software instead of through the image capture board. In addition, the preprocessing unit 40 converts the image data expressed in gray scale or color into binary data through bidirectional differential and bidirectional dress operations, thereby significantly reducing the amount of data. Play a role. Therefore, the defect inspection system 100 which concerns on this invention can detect the defect of a product in real time.

In the above, the configuration and operation of the circuit according to the present invention are shown in accordance with the above description and drawings, but this is merely described, for example, and various changes and modifications are possible without departing from the spirit of the present invention. .

According to the present invention as described above, the image data acquired through the CCD camera is directly processed by the hardware without going through the image capture board, and the amount of data to be processed in the main processor through the bidirectional derivative and bidirectional threshold is significantly reduced Real time defect detection can be performed.

Claims (8)

In a defect detection system for detecting a defect of a product: A CCD camera for receiving image data of the product; Preprocessing means for performing hardware preprocessing on the image data input from the CCD camera; And a main processor for detecting a defect position of the product in response to a preprocessing result generated from the preprocessing means, and determining whether the product is defective or not. The pretreatment means, A synchronization signal generation circuit connected to said CCD camera for generating a synchronization signal to said CCD camera; An A / D converter connected to the CCD camera to convert the image data transmitted from the CCD camera into digital image data; A digital interface coupled to the A / D converter for performing an interface between the digital image data and the preprocessing means; A bidirectional differentiator connected to the digital interface for performing bidirectional differential on the digital data; A bidirectional dresser connected to the bidirectional differentiator for converting the differentiated data into binary data form; Data storage means connected to the bidirectional dress for storing binary data generated from the bidirectional dresser; And input / output means connected to said data storage means and said main processor for transferring said binary data stored in said data storage means to said main processor. The method of claim 1, The main processor is any one of a computer and a microcomputer equipped with a defect detection program. The method of claim 1, The bidirectional differentiator and the bidirectional dresser determine whether or not the data advances in the forward or reverse direction when the derivative and dress operations are performed on the digital image data, thereby preventing previous data from affecting the next data. High speed defect detection system. In a method of operating a defect detection system for detecting a defect of a product: Receiving image data of the product; Performing bidirectional differential on the image data; Converting the differentiated data into binary data and determining a data propagation direction for the converted data; Determining whether the binary data is fed back in response to the determined data progress direction; Storing the data in data storage means when the binary data is not fed back; Transmitting the stored data to a main processor; And And determining the defect location generated in the product and the quality of the product in response to the transmitted data. delete delete delete delete