JPH01237440A - Method for detecting part mounted on board - Google Patents

Abstract

PURPOSE:To make it possible to remove a silk-printed part even if the silk- printed part is overlapped and to make it possible to remove an image at a land part, by providing a pair of polarizing plates, a pair of image forming lenses, polarizing filters and a digital image processing device. CONSTITUTION:A half mirror 7 and a mirror are arranged on light paths, and cameras A1 and B2 pick up the same field of view in the same direction. Polarizing filters A5 and B6 are attached in front of lenses 3 and 4 and transmit linearly polarized light beams having the difference in azimuth angles by 90 deg.. The filter A5 has the angle equal to the azimuth angle of polarized lighting which is emitted from a ring shaped polarizing plate A10. The filter B6 has the angle equal to the azimuth angle of polarized lighting emitted from a ring shaped polarized plate B12. A ring shaped lighting device A9 is a light projecting device. The regular reflected light from the plane of a substrate 13 is inputted into the cameras. Only a land part other than a part where lead wires are provided is detected. At the camera B2 through which the polarized light is transmitted, the lead wires, all of the land part and a silk printed part have high luminance relatively uniformly.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application"
The present invention relates to a method (hereinafter referred to as a component detection method) for generating an image that allows accurate measurement in a device that measures size, inclination, etc. from an image obtained by a camera and determines its quality.

"Conventional technology" Traditionally, the component detection method for inspecting board-mounted components is
Various methods have been proposed, but for example, when considering the inspection of the clinched state of lead wires of components, as shown in Figure 2, by performing oblique illumination from a shallow angle over the entire circumference of the board, A method was used in which the light incident on the camera from the land near the mirror surface was eliminated, and only the reflected light from the protruding lead wires was obtained.

"Problem to be Solved by the Invention" However, since the board is illuminated at a very shallow angle with emphasis on reducing the amount of light incident on the land, sufficient reflection from the lead wires can be obtained. Figure) Detection was unstable because illumination could not be performed. (Figure 4)
Also, the land part cannot be completely removed (noise remains).
. In addition, the board on which silk printing is mounted (Fig. 5) is
There was a problem in that the lead wire and the silk printing overlapped, as shown in Figure 6, making it impossible to accurately measure the length.

"Means for Solving the Problems" In order to solve the above problems, we do not focus on eliminating the incident light from the land area, but instead use an oblique illumination device that illuminates at an optimal angle, and a direction perpendicular to the substrate (or in the vertical direction). The system consists of an epi-illumination device that illuminates from a nearby direction), a camera equipped with a pair of polarizing plates, a polarizing filter, and an imaging lens that convert each illumination light into linearly polarized light orthogonal to each other, and a digital image processing device. , an image obtained by manipulating a polarizing filter to transmit light from an oblique illumination device, and an image obtained by manipulating a polarizing filter to transmit light from an epi-illumination device, for each element at the corresponding position. , the subtraction of the quantized luminance (a negative result is only O
) was performed using a digital image processing device.

``Function'' According to this method, even if the silk printing is overlapped, the silk printing can be reliably removed, and the image on the land can also be completely removed (no noise remains). Furthermore, since the Riet line is illuminated from the optimal angle, it can be detected stably.

"Example" An example of the present invention will be described below with reference to FIG. This embodiment relates to a method for obtaining an image suitable for measuring lead wires, which is applied to the lead wire detection apparatus described above.

The camera A1 and the camera B2 have a half mirror 7 and a mirror 8 arranged in the optical path, so that the camera A1 and the camera B2 take distance images of the same visual field from the same direction. The polarizing filter 5.6 attached to the front surface of the lens 3.4 transmits linearly polarized light having an azimuth angle of 90° from each other.
5 is equal to the azimuth of the polarized illumination emitted from the ring-shaped polarizing plate Δ10, and the polarizing filter 86 is the ring-shaped polarizing plate B1.
It is equal to the azimuth angle of the polarized illumination emitted from 2.

The ring-shaped illumination device 9 is an epi-illumination device, which is installed so that specularly reflected light from the substrate plane enters the camera.

In particular, the land portion has a very high brightness because it is close to a mirror surface.

Since the lead wires are not planar, almost no specularly reflected light from the lead wires enters the camera, and since the silk printing is on a diffusing surface, the brightness of these is sufficiently lower than that of the land portions. In other words, the ring-shaped illumination Δ has the role of detecting only the land portion excluding the 7S\ projecting portion of the lead wire. Fifth
If the field of view is shown in the figure, the image of camera A when only epi-illumination is used is as shown in FIG. 7.

In addition, the ring-shaped illumination B11 is an oblique illumination device from the optimum position for reflecting the lead wire, and the camera B transmits this polarized light (in this case, the lead wire, the land portion, and the silk printing all have a relatively even and high brightness.

(Fig. 8) On the other hand, the image seen by the camera in the case of only oblique illumination is as shown in Fig. 9.

This is because both the lead wire and the land are smooth enough to preserve the polarization azimuth due to irregularities.
This is because silk printing has a complex surface state and the polarization is canceled when there is a violation, so the light includes light that passes through the polarizing filter A. If we consider the image when the two lights are turned on at the same time, camera B will have the 8th
Similarly to the figure, the camera △ is as shown in Fig. 10.

The images obtained from each camera are manually input to a digital image processing device, and the operation of subtracting the 10th figure image from the 8th figure image (brightness subtraction) is performed. Assuming that both elements that result in a negative result are O, The result is as shown in FIG. 11, and an image in which only the lead wires without noise are extracted is obtained.

``Effects of the Invention'' Conventionally, the land and silk portions caused noise, making it impossible to detect components with high reliability, but with the present invention, the land and silk portions are completely removed, resulting in highly reliable detection. It is now possible to detect parts.

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[Brief explanation of the drawing]

FIG. 1 is a system configuration diagram of an embodiment of the present invention, FIG. 2 is an explanatory diagram of illumination positions, FIG. 3 is an example of an image obtained by illumination from an optimal illumination position, and FIG. An example of an image obtained by illumination from a position where there is little incident light from the land part. Figure 5 is an example of a board with silk printing. Figure 6 is an example of an image obtained by illumination from a position where there is little incident light from the land part. Figure 7 shows an example of an image obtained when illuminating from a position with little light.
An image of camera A obtained with epi-illumination only, FIG. 8 is an image of camera B obtained with illumination from the optimal illumination position, and FIG. 9 is an image of camera A obtained with illumination from the optimal illumination position. , Figure 10 shows camera A obtained by using both epi-illumination and illumination from the optimal illumination position.
The image shown in FIG. 11 is the resulting image. Patent applicant: Takagaku Seisakusho Co., Ltd. Engraving of the drawing (no changes to the content) Notebook 1 Order 2 Item Foot 3 Notebook 91 'Kaki b1 Sword Sugar 6 figure' Figure 9 Kuzu l - Kasumi procedural amendment (method) 1988 July 6th

Claims (1)

[Claims] In equipment that inspects the mounting status of components mounted on a board, a lighting device (
(hereinafter referred to as oblique illumination device) and the vertical direction of the substrate (or
An illumination device (hereinafter referred to as an epi-illumination device) that illuminates from a direction close to that direction (hereinafter referred to as an epi-illumination device), a pair of polarizing plates that convert each illumination light into linearly polarized light orthogonal to each other, and a photoelectric converter (hereinafter referred to as a camera) that detects a two-dimensional image. ), an imaging lens attached to the camera, a polarizing filter that selects the light that enters the camera, and a digital image processing device.The image is obtained by operating the polarizing filter so that the light from the oblique illumination device passes through. , subtraction of the quantized luminance for each element at the corresponding position of the image obtained by manipulating the polarizing filter to transmit the light of the epi-illumination device (all negative results are 0)
This is a board-mounted component detection method that uses a digital dual-image processing device to perform the following.