JP2624322B2 - Method for detecting the position of a feature of an object - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for detecting the position of a characteristic portion of an object, and sets an area for detecting the characteristic portion of the object within the field of view of a camera, and this area By calculating the extreme value of the change of the superimposed area or the non-overlapping area of the object, 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.

FIGS. 8 and 9 show a conventional pattern matching method. First, as shown in FIG. 8, 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. The operator enters the set check areas A1 to A4 and observes them, and detects 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.

Next, as shown in FIG. 9, 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 the respective corners Ka〜Kd, the positional deviations △ x, △ y, θ in the XY direction and the rotation direction of the electronic component are calculated. 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 sufficiently 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 to calculate the area of the overlapping portion where the feature detection area and the peripheral portion of the object overlap or the area of the non-overlapping portion which does not overlap, and the area of the overlapping portion or the non-overlapping portion. By detecting the position of the point where the extreme value of the change of the characteristic appears, the position of the characteristic portion of the object is detected.

(Operation) According to the above configuration, the position of the characteristic portion of the target object such as a corner is detected by calculating the position of the point where the extreme value of the change in the area of the superimposed portion or the non-superimposed portion appears.

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 condensing 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.
13, 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 wavy 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, the scanning shown in FIG. 3 is performed with an arbitrary point (for example, the intersection of the electronic component 2 and the plus side of the Y axis) as a starting point. In the figure, A is the field of view
The area A is a circle area for detecting a characteristic portion of the electronic component 2 set in 20. The area A is moved along the contour detected by the contour tracking means so that the area A and the peripheral edge of the electronic component 2 are moved. Area S of overlapping overlapping portion (shaded line portion) a
Is calculated.

FIG. 4 shows the result of the calculation.
In the figure, SO is the area of area A, and 〜 is the position of each point in FIG. When area A is moved along a line bisected by the contour,
The area of the superimposed portion a is S0 / 2 at a portion along the straight linear portion of the electronic component 2, but its corner, that is, the characteristic portion,
,, Becomes an extreme value (minimum value) S0 / 4. Therefore, the position of the characteristic portion (corner) can be detected by obtaining the XY coordinates of these points.

Once the coordinates of the feature part have been obtained in this way,
From this, the coordinates of the center O 'of the electronic component 2 can be calculated, and the displacements △ x, △ y (see FIG. 3) of the electronic component 2 in the XY direction can be easily known. Further, the error θ in the rotation direction can be easily calculated. Note that, in the above method, the coordinates of the characteristic part to are obtained by obtaining the extreme value (minimum value) of the area S of the superimposed portion a. In this case, the point at which the area of the non-overlapping portion b has a local maximum value (maximum value) is the position of the characteristic portion.

Embodiment 2 In FIG. 5, reference numeral 3 denotes a mini-transistor 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. The area S of the part a is obtained. FIG. 6 shows the result. The position of the characteristic portion can be obtained by obtaining the coordinates of the point (1) where the extreme value (maximum value and minimum value) appears. As described above, according to the present method, the coordinates of a characteristic portion such as a corner can be accurately obtained regardless of the shape of the object.

Embodiment 3 FIG. 7 shows a case where the present method 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 stand, and 6 is this support stand 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 shifts Δx, Δy, θ 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,
Direction deviations △ x and △ y,
Is rotated by a motor (not shown) in the θ direction about its axis, thereby correcting the error θ in the rotation direction. Then, when the electronic component P is mounted on the board 34, the errors △ x, △
y and 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, calculate the area of the overlapping portion where the feature detection area and the peripheral portion of the object overlap or the area of the non-overlapping portion which does not overlap, and change the area of the overlapping portion or the non-overlapping portion. By detecting the position of the point where the extreme value of the object appears, the position of the characteristic part of the object is detected, so that the position of the characteristic part of the object such as the corner of the electronic component is accurately detected. be able to.

[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, FIG. 4 is a characteristic view, and FIG. FIG. 6 is a plan view of another embodiment, FIG. 6 is a characteristic view, FIG. 7 is a partial side view of a rotary head type electronic component mounting apparatus, and FIGS. 8 and 9 are plan views of conventional means. 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] An outer periphery of an object is observed by a camera, and a contour of the object is detected. Then, an area for detecting a characteristic portion is moved along the outline, and the area for detecting the characteristic portion and the object are detected. By calculating the area of the overlapping portion where the peripheral portion overlaps or the area of the non-overlapping portion that does not overlap, and detecting the position of the point where the extreme value of the change in the area of the overlapping portion or the non-overlapping portion appears, A method for detecting the position of a feature of an object, comprising detecting the position of the feature.