JPH05302821A - Printed circuit board inspection device - Google Patents

Abstract

PURPOSE:To enable saving man power for inspection of printed circuit board, improving inspection accuracy and making repair work easy. CONSTITUTION:Provided are a first memory 205 registering the image of a printed circuit board properly loaded with parts as standard board, an input device 1 for taking in the image of the printed board to be an inspection object, a preprocessor circuit 203 for preprocessing the image taken in the input device 1, a second memory 204 for reserving the image processed with the preprocessor circuit 203, a comparison circuit 202 for comparing the images in the first and the second memories 205 and 204 to judge the coincidence of the two, and a display 4 for indicating the inspection result based on the output of the comparison circuit 202.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed circuit board inspection apparatus, and more particularly to an inspection apparatus for inspecting the mounting condition of parts on a printed circuit board.

[0002]

2. Description of the Related Art Conventionally, the inspection of the mounting state of parts on a printed circuit board has been conducted by visual inspection or electrical inspection. In the former, it is not easy to train and secure workers,
Further, there is a problem that the inspection accuracy is not stable and the speed is insufficient. In the latter case, in order to inspect in a semi-finished product state, it is necessary to create jigs, inspection programs, etc., and inspection in a state close to the product is costly for repairing defective products. Become.

[0003]

The present invention was devised to solve the above-mentioned problems of the prior art.
An object of the present invention is to provide an inspection device for a printed circuit board, which can improve an inspection system and facilitate repair work.

[0004]

A printed circuit board inspection apparatus according to the present invention compares a board on which parts are properly mounted with a board to be inspected as an image, and determines the board to be inspected based on the degree of coincidence between the boards. The quality is determined. According to the inspection device of the present invention, no visual inspection or electrical inspection is required.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, one embodiment of the inspection device according to the present invention will be described with reference to FIGS. In FIG. 1, the inspection device is composed of a video camera 1 which is an input system, an image processing section 2, a terminal device 3, and a display device 4 which is an output system. The image processing unit 2 further includes a control circuit 201, a central processing unit 202, a preprocessing circuit 203, a memory 204, a reference value memory 205, and an interface 206.

First, in step 101, an image of a printed circuit board having a plurality of clear markings is captured by the camera 1. Next, in step 102, the preprocessing circuit 203 performs differentiation processing on this image to extract edges. This ensures that the marking is extracted. In step 103, the central processing unit 2
In 02, it is judged whether or not the extracted marking has been taken into the proper position.

Then, in step 104, the preprocessing circuit 20 is applied to the image for which the marking is judged to be the proper position.
Noise removal is performed in 3. This makes it possible to obtain an image of the printed circuit board that is suitable for the inspection.
Then, in step 105, the noise processing result is stored in the memory 204 connected to the preprocessing circuit 203.

On the contrary, with respect to the image in which the marking is judged to be an inappropriate position, the diaphragm and the photographing angle of the camera 1 are corrected through the control circuit 201, and the photographing condition is set so that the proper marking position can be obtained. In this case, the processing from step 101 to step 103 is repeated until the camera 1 is set at the correct position. Alternatively, the image as it is may be temporarily stored in the memory 204 and then the position of the marking may be corrected on the memory 204.

The processing from step 101 to step 105 is first performed on the printed circuit board on which the parts are properly mounted, and the result is stored in the reference value memory 205 in advance.

In step 106, the central processing unit 202 compares the image of the reference printed circuit board and the image of the printed circuit board to be inspected, which are already stored in the reference value memory 205, and the degree of coincidence is calculated. That is, the central processing unit has a function as a comparison circuit.

Here, the following parameters can be adopted as the degree of coincidence. The ratio between the number of corresponding pixels having the same density and the total number of pixels in a 1.2-value image. 2. The ratio of the number of corresponding pixels whose density difference is less than a certain value and the total number of pixels in a multi-value image. Alternatively, the variances may be compared in a normalized histogram.

The above normalization is an operation of correcting the histogram so that the maximum value of the number of pixels and the altitude range of the image registered in the reference value memory 205 and the image to be inspected become equal.

The processing performed by the image processing unit 2 receives an instruction from the terminal device 3 such as a computer, and outputs the result calculated in step 106 to the display unit 4 via the interface 206. The quality of the printed circuit board to be inspected is determined based on. By thus determining the suitability of mounting parts by processing image data, high-speed inspection is possible and labor saving can be realized.

[0014]

As described above, according to the present invention, it is possible to provide an apparatus capable of saving labor, improving inspection accuracy, and facilitating repair work in a quality inspection of a printed circuit board.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of the present invention.

FIG. 2 is a flowchart illustrating an example of the present invention.

[Description of Reference Signs] 1 camera 4 display device 202 central processing unit 203 preprocessing circuit 204 memory 205 reference value memory

Claims (1)

[Claims] 1. A first memory for registering an image of a printed board on which parts are properly mounted as a reference board, an input device for taking in an image of a printed board to be inspected, and an input device for taking in the image. A pre-processing circuit that pre-processes the image, a second memory that holds the image processed by the pre-processing circuit, and a comparison circuit that compares the images in the first and second memories and obtains the degree of coincidence between them. And a display device for displaying the inspection result based on the output of the comparison circuit.