JP2906450B2 - Method of detecting feature of object - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for detecting a characteristic portion of an object, and sets an area for detecting the characteristic portion of the object in a field of view of a camera, and sets the area and the object to be detected. By comparing the curvature of the change of the superimposed part or non-superimposed area of the object with the curvature of the characteristic part of the master,
The position of the characteristic portion of the object is detected.

(Prior Art) For example, a pattern matching method is known as a method for inspecting whether electronic components such as an IC chip, an LSI chip, a resistor chip, and a capacitor chip are mounted at correct positions on a substrate.

9 and 10 show a conventional pattern matching method. First, as shown in FIG. 9, a corner which is a characteristic part of a reference image 100 serving as an inspection reference is placed in a field of view of a camera. It is placed in the set check areas A1 to A4 and observed, and the coordinates of the corners ka to kd of the superimposed portions a to d where the corners of the reference image 100 and the areas A1 to A4 overlap each other are detected and stored. Keep it.

Next, as shown in FIG. 10, the areas A1 to A4 are relatively moved in the X and Y directions with respect to the image 101 of the electronic component to be inspected, and the superimposed portions ad are corners of the image 101. Find the matching position that most overlaps the part, and calculate the angle Ka at that position.
KKd are regarded as the coordinates of the corners Ka′〜Kd ′ of the image 101, and from the XY coordinate values of each of the corners Ka〜Kd, the positional deviation △ x, △ y, △ θ Was calculated.

(Problems to be Solved by the Invention) However, in the above conventional method, the reference image 100
And the corner of the image 101 to be inspected are difficult to completely overlap with each other, and there is a problem that the inspection accuracy is not improved accordingly.

Therefore, an object of the present invention is to provide a means capable of accurately detecting the position of a characteristic portion of an object such as a corner.

(Means for Solving the Problems) For this purpose, according to the present invention, a camera is used to observe the outer periphery of an object, detect an outline of the object, and then set a feature detection area set in the field of view of the camera. Is moved along the contour, and the curvature of the change in the area of the overlapping portion where the feature detecting area and the peripheral portion of the object overlap or the non-overlapping portion where the overlapping portion does not overlap is determined. The position of the characteristic portion of the target object is detected by comparing the curvature of the part with the position of the point where the limit value appears.

(Operation) According to the above configuration, the curvature of the change in the area of the superimposed portion or the non-superimposed portion is collated with the curvature of the characteristic portion of the master, and the position of the point where the limit value appears is obtained. The position of the characteristic portion of the target object is detected.

Embodiment 1 Next, an embodiment of the present invention will be described with reference to an example of an appearance inspection unit that detects a displacement of an electronic component mounted on a substrate.

FIG. 1 is a perspective view of a visual inspection device, where 1 is a substrate,
Reference numeral 2 denotes an electronic component mounted on the substrate 1. Substrate 1 is XY
The substrate 1 is arranged on an XY direction moving device 5 composed of tables 3 and 4, and the substrate 1 is moved in the XY direction by driving the device 5. A visual inspection camera 6 such as a CCD area camera or a linear image camera is provided above the substrate 1, and a light source 7 and a light collecting element 8 are provided obliquely above the substrate 1. Reference numeral 10 denotes a control unit connected to the camera 6, which includes a D / A converter 11, a frame memory 12, and a binarization processing unit 1.
3. It is composed of a superimposed area calculator 14, a CPU 15, and the like.

FIG. 2 shows that the electronic component 2 is scanned by the above-described device.
3 shows a state in which the contour tracking is performed. In the figure,
Reference numeral 20 denotes the field of view of the camera 6, and reference numeral 2 denotes the electronic component. As shown by the broken line arrow, the outer periphery of the electronic component 2 is observed starting from the origin O of the XY coordinates, and the XY coordinates of the outline are detected. Since the brightness of the substrate (white) 1 and the brightness of the electronic component (black) 2 are different, the outline can be easily detected by the binarization processing means. Such a contour tracking means is a well-known means.

After the contour tracing is completed as described above, an arbitrary point (for example, an intersection between the electronic component 2 and the plus side of the Y axis)
The scanning shown in FIG. In the drawing, A is a circle area for detecting a characteristic portion of the electronic component 2 set in the field of view 20. The area A is moved along the contour detected by the contour tracking means, and the area A and the electronic The curvature fi of the change in the area of the overlapping portion (shaded portion) a where the peripheral portion of the component 2 overlaps is calculated. The calculation process is performed by the control unit 10.

4 (a), (b) and (c) show the coordinates of the contour and the calculation results thereof. In FIG. 4 (a), symbols "-" indicate the positions of the respective points in FIG. When the area A is moved along a line bisected by the contour, the area of the superimposed portion a is Ａ of the area of the area A at a portion along the straight linear portion of the electronic component 2 and the curvature fi Does not change, but changes at the corners, that is, at the characteristic portions,... (See FIG. 3B). FIG. 5 shows a waveform of the curvature gi of the characteristic portion of the master. The curvature gi is a curvature obtained when the above-described scanning is performed on an electronic component having an ideal shape, and is obtained theoretically and experimentally.

As shown in FIG. 4 (b), the waveform of the curvature gi of the master is scanned in the direction of arrow N to obtain the curvature fi.
自 (fi-gi) ² of the difference from FIG. 3C shows the result, in which (a), (b),
At four points (c) and (d), an extreme value (minimum value) appears. Therefore, the points (a) to (d) where this limit value appears are the characteristic parts of the electronic component 2,.
Position.

The means for checking the curvature fi and the curvature gi is arbitrary. For example, the difference Σ (fi-gi) between the two may be simply obtained. In short, the limit value is accurately obtained by comparing the two. Anything should do.

Once the coordinates of the characteristic parts are obtained in this manner, the coordinates of the center O 'of the electronic component 2 are calculated from this, and the displacements △ x, △ y of the electronic component 2 in the XY direction (FIG. 3) See). Also, the error in the rotation direction △
θ can be easily calculated. Note that, in the above method, the coordinates of the characteristic portions to are obtained by calculating the curvature of the change in the area of the superimposed portion a. is there.

Embodiment 2 In FIG. 6, reference numeral 3 denotes a minitransistor having three terminal portions 3a, 3b, 3c. In this case, similarly to the case of the first embodiment, after the contour is traced along the outer periphery to obtain the coordinates of the contour, the characteristic portion detection area A is moved along the contour to be superimposed. Curvature fi of the change in area of part a
Ask for. FIGS. 7 (a) and 7 (b) show the results. In FIG. 7, 〜 indicates the position of each point in FIG. This is also similar to the case of the first embodiment.
The waveform of the curvature gi of the master is scanned in the direction of the arrow N, and the self-retention Σ (fi-gi) ² of the difference between the curvature fi and the curvature gi is obtained (see FIG. 13B). By determining (a), (b), and (c), the positions of the leads 3a to 3c, which are characteristic parts of the electronic component 3, are determined.

Embodiment 3 FIG. 8 shows a case where the present invention is applied to a rotary head type electronic component mounting apparatus. 31 is a rotary head, 32 is a number of transfer heads vertically suspended along the outer periphery of the head 31, 33 is its nozzle, 34 is a substrate positioned on the xy-direction moving device 35, 36 is a support, and 6 is this support. The camera P provided in 36 is an electronic component.

In this apparatus, while rotating the rotary head 31 at a pitch around its axis, a chip supply unit (not shown) sucks up the electronic component P at the lower end of the nozzle 33 and takes up the same. At the same time, the electronic component P is mounted on the substrate 34.

The camera 6 is provided between the chip supply unit and the substrate 34, and the nozzle
By observing the electronic component P attracted to the device 33 from below, the positional deviations Δx, Δy, Δθ of the electronic component P are detected as described in the first embodiment. Then, by driving the xy direction moving device 35 to move the substrate 34 by the same amount in the XY direction,
In addition to correcting the 位置 x and △ y displacements in the XY direction,
By rotating the motor 33 (not shown) in the θ direction about its axis, the error Δθ in the rotation direction is corrected, and then the electronic component P is mounted on the board 34.
x, △ y, △ θ can be corrected and mounted on the substrate 34.

The method can be further used in various fields,
For example, detection of a characteristic portion of a circuit pattern printed on a substrate can be performed, and the object may be other than electronic components.

(Effects of the Invention) As described above, according to the present invention, after observing the outer periphery of an object using a camera and detecting the contour of the object, the feature detection area set in the field of view of the camera is set as described above. By moving along the contour, the change in the area of the overlapping portion where the feature detection area and the peripheral portion of the object overlap or the non-overlapping portion that does not overlap is determined as the curvature, and then this curvature and the master feature The position of the characteristic part of the object is detected by comparing the curvature with the position of the point where the extreme value appears, so the characteristic part of the object such as a corner or a lead of an electronic component is detected. Position can be accurately detected,
In particular, there is an advantage that the position of the characteristic portion can be accurately detected while eliminating the adverse effect of noise.

[Brief description of the drawings]

1 shows an embodiment of the present invention. FIG. 1 is a perspective view of an appearance inspection apparatus, FIGS. 2 and 3 are plan views during inspection, and FIGS. 4 (a), (b), and FIG. (C) is a graph, FIG. 5 is a curvature waveform diagram of a characteristic portion of the master, FIG. 6 is a plan view of another embodiment, FIGS. 7 (a) and (b) are graph diagrams, and FIG. FIGS. 9 and 10 are plan views of a conventional means of the rotary head type electronic component mounting apparatus. 2,3, P… Object 6… Camera 20… Camera view A… Characteristic part detection area a… Superimposed part b …… Non-superimposed part

Claims (1)

(57) [Claims] 1. An outer periphery of an object is observed by a camera, an outline of the object is detected, and then a feature detection area set in the field of view of the camera is moved along the outline. Find the curvature of the change in the area of the overlapping portion where the feature detection area and the peripheral portion of the object overlap or the non-overlapping portion where it does not overlap, and then compare this curvature with the curvature of the master feature portion, A method for detecting a characteristic part of an object, wherein a position of a characteristic part of the object is detected by obtaining a position of a point where a symbol appears.