JPH06265321A - Outer shape inspection method - Google Patents

Abstract

PURPOSE:To provide an outer shape inspection method for inspecting outer shape by separating and discriminating the images of a plurality of shape cutting lines picked up by a camera even if they overlapped one another. CONSTITUTION:When two cameras are laid out so that angles theta1 and theta2 formed by laser beams a, b, and c and each light axis are set to 45 deg. and 25 deg., respectively, and then the first images of the shape cutting line which is picked up by the camera 2 and is formed at a soldering part 1 by the laser beams a, b, and c overlap one another, the second images of the shape cutting line picked up by the camera 3 are allowed to overlap to separate and discriminate the first images, thus measuring the shape of the surface of the soldering part 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a visual inspection method,
In particular, it is useful when applied to the appearance inspection of a printed circuit board on which chips, ICs, etc. are mounted, or a printed circuit board on which cream solder printing is performed before mounting chips, ICs, etc.

[0002]

2. Description of the Related Art Conventionally, a method called an optical cutting method or a triangulation method has been used as one of appearance inspection methods for a soldered portion of a printed circuit board. This is because the surface of the soldering part to be inspected is first irradiated with a linear laser or scanned with a beam laser to form a linear laser beam of the linear laser or the beam laser scattered by the unevenness of the surface. The shape cutting line is formed, and then this shape cutting line is imaged with a camera from a direction having a predetermined angle with respect to the optical axis of the laser light, and each portion of the shape cutting line obtained from the image at this time is formed. Based on the corresponding coordinate data, the shape of the surface of the soldered part is measured by the principle of triangulation.

In order to reduce the time required for the appearance inspection of the printed circuit board, it is possible to simultaneously irradiate the soldering portions with a plurality of laser beams to form a plurality of shape cutting lines and perform the appearance inspection. is there.

[0004]

However, when the number of shape cutting lines increases in the prior art as described above and the interval between the adjacent shape cutting lines becomes narrow, when these are taken by the camera, the shape cutting lines The images overlap each other, which image corresponds to which shape cutting line,
It becomes difficult to determine the shape, which makes it difficult to measure the shape of the soldered portion.

For example, as shown in (1) and (2) of FIG. 3, two laser beams a are applied to the soldering portion 1 of the printed board.
1, b1 are irradiated, and two linear shape cutting lines a1 ′ and b1 ′ formed on the surface of the soldering portion 1 at this time are reflected by the angle θ ₃ between the laser beams a1 and b1 and the optical axis. When the image is taken by the camera 4 arranged at 45 °, the shape cutting line a
When the distance between 1'and b1 'is relatively wide, the condition shown in FIG.
As shown in FIG.
If images a1 ″ and b1 ″ of 1 ′ and b1 ′ are obtained, but the interval between the shape cutting lines a1 ′ and b1 ′ is too narrow,
As shown in (2), the images a1 ″ and b1 ″ of the shape cutting lines a1 ′ and b1 ′ overlap each other.

Although it is conceivable to make the angle θ ₃ smaller than 45 ° so that the images do not overlap each other, however, if the angle θ ₃ is made smaller, the imaging resolution is lowered and the accuracy of shape measurement is reduced accordingly. Will fall.

In view of the above-mentioned conventional technique, the present invention is an appearance inspection method capable of performing a visual inspection by separating and determining even if images of a plurality of linear shape cutting lines taken by a camera overlap each other. The purpose is to provide.

[0008]

The structure of the present invention for achieving the above object is to irradiate a plurality of laser beams on the surface of a visual inspection object and to form a plurality of linear shape cutting lines on the surface. In the appearance inspection method of imaging the shape cutting line with a camera and measuring the shape of the surface of the appearance inspection object by a triangulation method, the angles formed by the optical axis of the laser beam and the respective optical axes are different from each other. 2 cameras are installed so that the plurality of shape cutting lines are imaged by the two cameras, respectively, and the first shape is an image of the plurality of shape cutting lines taken by the one camera having the larger angle. When the images overlap each other, the second image which is the image of the plurality of shape cutting lines captured by the other camera having the smaller angle and which is separated without overlapping each other is referred to as the second image. Overlay on the image of 1 By identifying first image and a correlation between the second image, characterized in that the correspondence relationship between the first image and the plurality of shaped cutting lines to separate discrimination.

[0009]

According to the present invention having the above structure, when the first images overlap each other, the second image is superposed on the first image, and the first image and the plurality of shape cutting lines are combined. After separating and determining the correspondence, that is, which image in the first image corresponds to which shape cutting line, the coordinate data is obtained from this first image, and the shape of the surface of the appearance inspection object is measured. .

[0010]

Embodiments of the present invention will now be described in detail with reference to the drawings.

First, as shown in FIG. 1, two cameras 2,
Place 3 at different angles. One of the cameras 2 is arranged so that an angle θ ₁ formed by its optical axis and the parallel laser beams a, b, and c emitted from the vertical direction to the soldering portion 1 of the printed circuit board is 45 °, and The other camera 3 is arranged so that the angle θ ₂ formed by its optical axis and the laser beams a, b and c is 25 °. After that, three shape cutting lines (not shown) formed on the surface of the soldering portion 1 by the irradiation of the laser beams a, b, and c are provided on the camera 2.
3 from each angle (45 ° and 25 °).

FIG. 2A is a diagram showing an image of the shape cutting line taken by the camera 2. As shown in the figure, the first images a ', b', and c'of the shape cutting line overlap each other. In such a case, the first image a ′,
It becomes difficult to determine which of the above-mentioned shape cutting lines corresponds to b ′ and c ′.
It becomes difficult to obtain the coordinate data from the images a ', b', and c'and measure the shape of the surface of the soldering portion 1.

FIG. 2B is a diagram showing an image of the shape cutting line taken by the camera 3. As shown in the figure, in the second image a ″, b ″, c ″ of the shape cutting line, the angle θ ₁ of the camera 2 is 45 °, whereas the angle θ ₂ of the camera 3 is 25 °. 2 (1), they are separated from each other without overlapping each other, so that it is determined which of the shape cutting lines the second images a ″, b ″, and c ″ correspond to. It is easy to determine.

Then, as shown in FIG. 2C, the second images a ", b", and c "are overlaid on the first images a ', b', and c ', and the correlation between them is identified. Yes, the first
Each of the images a ′, b ′, c ′ of the second image a ″,
Which of b "and c" is closest is identified.

Thus, the correspondence relationship between the first images a ', b', c'and the shape cutting line, that is, the first images a ',
It is discriminated separately which of the shape cutting lines each of b'and c'corresponds to.

According to the above-described embodiment, even if the first images a ', b', and c'captured by the camera 2 overlap each other, the second images a ", b" captured by the camera 3 are overlapped with each other. , C ″ by superimposing the first images a ′, b ′, c ′
It is possible to determine the shape of the surface of the soldering portion 1 by determining the coordinate data from the first images a ', b', c'after separately discriminating which of the shape cutting lines each corresponds to. .

[0017]

As described in detail with reference to the embodiments, the present invention arranges two cameras at different angles so that images of a plurality of shape cutting lines taken by one camera are mutually different. Even if they overlap, they can be separated and distinguished. Therefore, it is possible to irradiate a larger amount of laser light onto the visual inspection object at the same time, and thus it is possible to perform a highly efficient visual inspection.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an arrangement of two cameras according to an embodiment of the present invention.

2 (1) and (2) are views showing an image of a shape cutting line respectively taken by two cameras, and (3) is (1), (2).
It is a figure which shows the state which overlapped the image shown in FIG.

FIG. 3A is an explanatory view showing the arrangement of a camera according to a conventional technique, and FIG. 3B is a view showing two shape cutting lines formed by two laser beams.

FIG. 4 (1) is a diagram showing an image in the case where the interval between two shape cutting lines is wide, and FIG. 4 (2) is a diagram showing an image in the case where the interval is narrow.

[Explanation of symbols]

 1 soldering part 2, 3 camera a, b, c laser light a ′, b ′, c ′ image of shape cutting line imaged by camera 2 a ″, b ″, c ″ of shape cutting line imaged by camera 3 image

Claims (1)

[Claims] 1. A surface of an appearance inspection object is irradiated with a plurality of laser beams to form a plurality of linear shape cutting lines on the surface, and the shape cutting lines are imaged by a camera to perform triangulation. In the appearance inspection method for measuring the shape of the surface of the appearance inspection object, two cameras are installed so that the angles formed by the optical axis of the laser beam and each optical axis are different, When the first images, which are images of the plurality of shape cutting lines captured by one of the cameras having a large angle, overlap each other while capturing the plurality of shape cutting lines, the other of the smaller angles is used. A second image, which is an image of the plurality of shape cutting lines captured by a camera and in which the respective images are separated without overlapping, is superimposed on the first image, and the first image and the second image Identifying correlations with images More, appearance inspection method characterized by the correspondence between the first image and the plurality of shaped cutting lines to separate discrimination.