JPH0210204A - Object detection method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an object detection method for inspecting the presence of a part of a predetermined size as an inspection object at a specific position in an inspection process during a manufacturing process. It is something.

2. Description of the Related Art A method using the shadow of an object to be inspected has been proposed as one method for inspecting the presence of an object to be inspected with predetermined dimensions at a specific position. This method extracts the image of the shadow part of the inspection object from the binary image obtained when the inspection object is illuminated by a lighting device installed diagonally above the inspection object, and determines the center of gravity etc. from the shape. The position and presence or absence of the object to be inspected is detected by calculating the feature amount and comparing it with pre-registered numerical values.

Problems to be Solved by the Invention However, according to the conventional method described above, in order to obtain an image of a specific shape of the shadow part, a threshold value that can distinguish the shadow from the other parts of the inspection object is first set. It is necessary to set the density value that is to be binarized into white and black at a certain brightness value called ``black''. Even if settings are made taking into account the conditions, etc., it is not always possible to obtain a shadow image with a predetermined shape. Furthermore, the larger the allowable range in which a good inspection object can exist, the wider the search range for shadows must be. There is a problem in that the shapes of the obtained shadows vary, the possibility of detecting extra information (noise) outside the shadow increases, and the position detection accuracy deteriorates.

Means to Solve the Problem Therefore, in the object detection method of the present invention, a plurality of lights are installed diagonally above the object to be inspected, and each light is sequentially illuminated to create a shadow of the object to be inspected. Within the allowable range, the approximate location of the object to be inspected is determined using features such as the center of gravity of one or several of those shadows, and based on that information, the search range is limited to a small size. Later further,
The method is to perform detailed position detection processing of the object. Here, position detection processing means, within a pre-specified range,
It refers to a series of arithmetic processing groups with extremely sensitive detection sensitivity that can distinguish subtle differences in brightness.

Effect of the Invention The present invention uses the above method to determine the approximate location of an object by using the shadow of the object within the allowable range, and eliminates unnecessary noise information by limiting the search range for position detection processing to a small size. This improves the reliability of position detection processing, and compared to the method of directly detecting the position of an object from the shape of the object's shadow itself, it is more stable and less susceptible to variations in the shape of the shadow and the effects of extra noise information. detection becomes possible.

Example An embodiment of the present invention will be described below with reference to the drawings.

Fig. 1 is a flowchart of the object detection method of this embodiment, and Fig. 2 is a chip component mounting inspection device (hereinafter referred to as
1 is a schematic configuration diagram of a chip inspection device (abbreviated as a chip inspection device). The chip inspection apparatus of this embodiment inspects the position of a chip component 9 mounted on a printed circuit board s, and uses the object detection method of the present invention.

A chip component 9 that is an object to be inspected and lighting devices 1° to 13
, a TV camera 1 for inputting images to the image recognition unit 16
The positional relationship with 4 is as shown in FIG. 2, and in order to inspect chip components at other locations, the illumination device and TV camera are moved in parallel on the printed circuit board by a robot.

Now, the operation of the chip inspection apparatus according to the embodiment will be explained based on FIG. As preprocessing, data such as the position, external dimensions, and type of each chip component are input to the image recognition unit 15, which controls the entire processing such as image processing as a chip inspection device, and the relative position from the center of gravity of the shadow and the allowable range are determined. Set it. First, in step 1 of inspection, the illumination 1o is emitted, and the shadow 16 of the chip component 9 is
cause Subsequently, in step 2, the position of the center of gravity P1 of the shadow is calculated from the shape of the shadow obtained in step 1. Similarly, the lights 11 to 13 are sequentially emitted to produce shadows 17 to 19 corresponding to each light, and the center of gravity positions P2 to P4 are calculated from their shapes. Next, in step 3, the position P determined in advance by the relative position from each of P1 to P4 is determined, and in consideration of the size of the inspection object taught in advance in step 4, the position P is determined in accordance with the predetermined tolerance range. Check the positional relationship. If the object to be inspected does not exist within the allowable range due to missing parts, etc., the predetermined shape corresponding to shadows 16 to 18 cannot be obtained, so the position of P found from P1 to P4 is compared to the normal case. This is often outside the allowable range considering the size of the object to be inspected, and many NGs due to missing parts are determined in this step. If it is determined in step 4 that it is within the allowable range, based on the previously determined position P, the search range for position detection processing according to the size of the inspection object registered in advance is determined. (Step 6). The size of the search range set here for the position detection processing is set to be smaller than the allowable range in which a non-defective object may exist. Position detection processing is performed within the search range set in step 6. Here, the position detection process is a series of arithmetic processes with extremely sensitive detection sensitivity that distinguishes subtle differences in brightness within a specified range and detects the point of change. , by applying the above-mentioned position detection process to the outer shape of the part to be inspected, the outer shape of the object to be inspected is detected, and the position coordinates of each vertex thereof are calculated (
Step 6). Based on the positional coordinates of each vertex determined in step e, the detailed position and dimensions of the object to be detected are determined, compared with pre-registered conditions, and a final judgment of quality is made (step 7). .

Effects of the Invention As described above, according to the present invention, by determining the approximate location of the object by using the shadow of the object to be inspected, it is possible to perform position detection processing over the entire allowable range of the object to be detected. Even in cases where detection accuracy decreases due to excessive noise information being detected, the search range for position detection processing can be limited to a smaller size, which reduces the variation in shadow shape compared to conventional methods. This enables stable detection that is less susceptible to the effects of noise and redundant image information. Furthermore, in areas where it is difficult to distinguish between shadows and other parts due to the presence of silk printing or holes on the board around the object to be inspected, we will use the shadows in advance to calculate the position of the object to be inspected. By selecting some of them, it is possible to cope with the diversification of the objects to be inspected, and to improve the inspection reliability of the sea layer.

[Brief explanation of the drawing]

FIGS. 1a and 1b are plan views of an object according to an embodiment of the present invention. 9...Inspection object, 10-13...Lighting device, 14...TV camera, 15...
Image recognition section. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 1

Claims (1)

[Claims] The first step is to place a plurality of lights diagonally above the object to be inspected and emit light from each of the lights in sequence to create a shadow on the object to be inspected. A second step of determining the approximate location of the object to be inspected using the feature quantity, a third step of narrowing down the search range based on the information in this second step, and after this third step, An object detection method characterized by performing position detection processing of an object to be inspected.