JP2001022940A - Method and device for image recognition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide image recognizing method and device, capable of accurately recognizing the area of an object having point symmetry. SOLUTION: A 1st template 30 including a prescribed area 40a is prepared, an image 40 is subjected to template matching with the 1st template to recognize the prescribed area. An area 41, covering the recognized prescribed area, is cut out as a template and turned by 180 deg. to prepare a 2nd template 42, and template matching is performed by using the template 42 to recognize the prescribed area again. A center C of the prescribed area is operated from a reference point A on an area covering the prescribed area and a point B on the 2nd template, corresponding to a reference point of when the prescribed area is recognized again. In this configuration, the 1st template is defined as a template with which rough positioning is performed, the prescribed area can first be recognized with rough accuracy by using the template, and the center of the area which has point symmetry can be calculated with high accuracy because the 2nd template is an accurate template formed on the basis of a real image.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for recognizing an image, and more particularly to a method for recognizing a point-symmetric region in which the same shape exists continuously, such as an electrode of a printed circuit board or a mask of a stencil electrode. The present invention relates to an image recognition method and apparatus for performing the above.

[0002]

2. Description of the Related Art Conventionally, in a screen printing machine, solder printing is performed by pressing (squeezing) solder onto a printed board via a stencil (mask). In this case, it is necessary to align the printed circuit board and the stencil in a predetermined positional relationship in order to print the solder on the printed circuit board with high accuracy. And aligning. Specifically, the printed circuit board is imaged from above the mark, and the stencil is imaged from the side in contact with the printed circuit board. The position of the mark is recognized by image recognition, and the printed circuit board and the stencil are accurately positioned.

In this case, as shown in FIG. 1A, a reference mark 1a is provided on each of a printed circuit board and a stencil 1.
If exists, the reference mark is imaged, the center of gravity is calculated from the image, or the image of the reference mark is registered in advance to create a template, and template matching is performed using the template in which the captured image of the reference mark is registered. The printed circuit board or stencil is positioned. If there is no reference mark for positioning the printed circuit board or stencil 2 as shown in FIG. 1B, the electrode 2a of the IC is used as a reference mark, and this is registered in advance as a reference mark. , The template matching is executed to position the printed circuit board and the stencil. When registering a template using the electrode 2a of the IC as a reference mark, if the template 3 is registered so that the electrode 2a is located at the center of the template as shown in FIG. For recognition, as shown in FIG.
A template 4 including a portion other than a is created and registered as a template so as not to be confused with other electrodes.

[0004]

However, FIG.
As shown in (F), when the printed circuit board or the stencil 6 imaged has an inclination, there is a problem that the displacement of the electrode 2a itself becomes large and accurate positioning cannot be performed. As a cause of the increase, when a portion other than the electrode to be positioned is included in the template 4 as shown in FIG. 1D, a template in which the center of the electrode 2a matches the center of the template 4 is used. When extracted, the electrode 2a is inevitably similar to the other electrodes. Therefore, the center position of the electrode 2a is created from a pattern having an offset of △ X and △ Y from the center of the template (FIG. 1D). In the pattern indicated by, ΔY is regarded as almost 0). Then, as shown in FIG. 1 (F), the printed board or the stencil 6 is inclined. If template matching is performed on the template already registered in this state, the position indicated by the dotted line is recognized (first registration). Find the shape that most closely resembles the template that was created). When the position indicated by the dotted line is recognized, the position of the electrode 2a is regarded as △ X and △ Y from the center. Therefore, the recognition result includes △ x and △ y errors shown in FIG.

Further, as shown in FIG. 1E, even if the center of the template 5 and the center of the electrode 2a match, if the template is not point-symmetrical, the matching amount differs but a shift occurs. When the center of the electrode 2a is coincident with the center of the template 3 as shown in FIG. 1 (C), there is no offset from the center of the template, and positioning is performed with respect to the electrode itself. If it occurs, the error will be minimal.

As described above, when electrodes on a printed circuit board or a stencil are used as reference marks, the electrodes cannot be formed in the center of the template and in a point-symmetrical shape. There was a point.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an image recognition method and apparatus capable of accurately recognizing a point-symmetric object region. I do.

[0008]

According to the present invention, there is provided an image recognition method and apparatus for recognizing a point-symmetric predetermined area in an object by imaging the object. Creating a template, recognizing the predetermined area by performing template matching of the image of the target object with the first template, cutting out an area covering the recognized predetermined area as a template, rotating it 180 degrees,
And re-recognizing the predetermined area by performing template matching using the second template. A point on the area covering the predetermined area and a point when the predetermined area is recognized again The center of the predetermined area is calculated from a corresponding point on the second template.

In such a configuration, the first template can be used as a template for rough positioning, and a predetermined area can be first recognized with coarse accuracy using this template. Then, the region covering the recognized predetermined region is cut out as a template, and the predetermined region is recognized again using the second template obtained by rotating by 180 degrees, and the center of the predetermined region is obtained. Since the second template is an accurate template formed based on the real image, the center of the point-symmetric region can be obtained with high accuracy.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

In the following description, in the flow of processing of correcting the position of a printed circuit board of a screen printing machine, correcting the position of a stencil, positioning and printing each, positioning, recognition of a reference position of a printed circuit board immediately before printing, stencil reference It is implemented as position recognition, and the screen printer has the recognition method according to the present invention, so that more reliable positioning can be realized even when there is no reference mark on the printed circuit board or stencil. However, the present invention is not limited to this embodiment, and can be used for recognizing a reference position or area or correcting the position when positioning various objects.

FIG. 2 shows the configuration of an image recognition apparatus according to an embodiment of the present invention. In the figure, reference numeral 10 denotes a stencil (mask for performing solder printing), and a pattern 10 formed on the stencil 10 is used.
The solder is printed as a print pattern 11a on the printed circuit board 11 by a screen printing machine (not shown) via a. For accurate printing, the stencil 10 and the printed board 11 are aligned.

For this purpose, the reference mark or the electrode is imaged using the imaging device 12. The imaging device 12 includes a stencil illumination device 13 and a stencil optical path prism 1.
4. A stencil CCD camera 15, a printed circuit board illumination device 16, a printed circuit board optical path prism 17, and a printed circuit board CCD camera 18;
The stencil illuminated by the
The printed circuit board imaged by the D camera 15 and illuminated by the illumination device 16 is imaged by the CCD camera 18 via the prism 17.

The images picked up by the CCD cameras 15 and 18 are A / A under the control of the CPU 21 of the image processing device 20.
The data is converted into a digital signal by the D converter 22 and stored in the image memory 23. Further, the image processing apparatus is provided with a template memory 24, in which images registered in advance are stored as templates. Also, the image processing device 20
Is connected to a monitor 25 so that an input image, a template image, or a processed or recognized image can be displayed.

The flow of image recognition in the apparatus having the above-described configuration will be described below.

First, as shown in FIG. 3, a teaching operation is performed as preprocessing. As shown in FIG. 1B, when the reference mark does not exist on the printed circuit board and the stencil, the imaging device 12 moves above the electrode of the printed circuit board 11 selected by the teaching operator, and the printed circuit board in the imaging device 12 The illumination device 16 is turned on, the printed board 11 is imaged by the printed board CCD camera 18 via the printed board optical path prism 17, and the image data is taken into the image memory 23.

Subsequently, in step S1, FIG.
The template 30 is registered so as to include a portion other than the electrode 30a to be detected as shown in FIG. Next, in step S2, as shown in FIG. 4B, a search window 31 is set in a local region of only the electrode 30a in the registered template 30. Subsequently, in step S3, as shown in FIG. 4C, the center of gravity G of the electrode 30a in the set local region 31 is calculated by the CPU 21, and in step S4, as shown in FIG. Offset {X,} from template center O to electrode center of gravity G
Y is registered (not displayed because ΔY in FIG. 4D is 0). Similarly, registration of a template including the electrodes of the stencil 10 is also performed.

In the production operation, first, the stencil is positioned. As shown in the flow of FIG.
When receiving a command for positioning the electrodes of the stencil from a host (not shown) as a recognition procedure, the 21 sets the stencil template 30 created as described above in the template memory 24 (step S10).

Further, information about electrodes set in advance is received from the host, and the information is set in its own memory (not shown). At this time, the imaging device 12 has already been moved to a predetermined position where the electrodes are present by a command from the host. When the condition setting for recognition in step S11 is completed, the stencil lighting device 13 is turned on by the CPU 21, and the image of the stencil portion where the electrodes are present is transmitted through the stencil light path prism 14 to the stencil CC.
An image is captured by the D camera 15 and the image data is A / D
The data is taken into the image memory 23 via the converter 22 (step S12). The image 40 thus captured
Is shown in FIG. 6 (A).

When the imaging is completed, the CPU 21 proceeds to step S
In step 13, template matching is performed using the registered template 30 and the captured image 40, and in step S14, the center coordinates of the electrode 40a are calculated based on the recognition result. At this time, as shown in FIG. 6B, if the stencil image 40 is tilted, FIG.
After the template matching is performed as shown in (1), when the offset from the center is converted, a position slightly shifted from the original center of the electrode is recognized. In order to avoid the deterioration of the detection accuracy due to this error, an area 41 capable of covering the electrode 40a is set from the shifted position in consideration of the preset electrode size as shown in FIG. 6C. (Step S15). For example, assuming that the size of the electrode 40a is h in the horizontal direction and v in the vertical direction, the set area is enlarged and shown in FIG. At this time, the coordinates of the reference point A at the upper left of this area are registered as the calculation reference coordinates (1) (step S1).
16).

Next, the set area 41 is rotated 180 degrees around its center point (step S17), and the rotated area is registered as a template 42 in the template memory 24 as shown in FIG. And this 180
The template matching is performed again using the template 42 rotated by degrees and the captured image 40 (step S).
18, S19). At this time, the region for performing the template matching does not need to cover a wide area because the center of the template is almost grasped, and may be a range in which the neighboring electrode does not enter near the template acquisition.

As shown in FIG. 6F, when the position of the electrode 40a is recognized in the template matching again, the point B at the lower right of the template 42 (corresponding to the point rotated 180 degrees from the reference point A) is determined. The coordinates are registered as calculation reference coordinates (2) (step S20). Then, the calculation reference coordinates (1) and the calculation reference coordinates (2) previously registered in step S21.
Is calculated as the center coordinates of the electrode 40a. The center of the electrode 40a thus obtained is shown as C in FIG. 6 (G).

The concept of performing template matching again using a template obtained by rotating the template by 180 degrees, and setting the center of the template position as the center of the object is also described in Japanese Patent Publication No. 8-12050. The offset between the center of the template and the center of the recognition target (electrode) can be canceled to accurately recognize the center position of the recognition target. If the recognition target is point symmetric,
Its shape and size are arbitrary. The reference point A is not necessarily limited to the periphery of the area, but may be any point in the area. However, the longer the distance between A and B, the more accurate the center position is obtained.

[0024]

As described above, according to the present invention,
The first template is a template for rough positioning, and a predetermined area can be first recognized with coarse accuracy by using the template. Then, an area covering the recognized predetermined area is cut out as a template, and 18
Since the predetermined area is again recognized and the center of the predetermined area is obtained by using the second template obtained by rotating by 0 degree, an accurate template formed based on the real image is obtained. From
The center of the point-symmetric region can be obtained with high accuracy.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram for explaining a problem of recognizing a position of an electrode of a printed circuit board or a stencil.

FIG. 2 is a configuration diagram showing a configuration of an image recognition device of the present invention.

FIG. 3 is a flowchart illustrating a process of creating a template as preprocessing.

FIG. 4 is an explanatory diagram showing a process of creating a template as preprocessing.

FIG. 5 is a flowchart illustrating a process of recognizing a region of a symmetric object by template matching.

FIG. 6 is an explanatory diagram showing a process of recognizing a region of a symmetric object by template matching.

[Explanation of symbols]

 Reference Signs List 10 stencil 11 printed board 12 imaging device 13 stencil lighting device 15 stencil CCD camera 16 printed board lighting device 18 printed board CCD camera 20 image processing device 21 CPU 23 image memory 24 template memory

Claims (2)

[Claims] 1. An image recognition method for recognizing a point-symmetric predetermined area in an object by imaging the object, creating a first template including the predetermined area, and converting the image of the object into the first image. A template matching is performed with a template to recognize the predetermined area, an area covering the recognized predetermined area is cut out as a template, rotated 180 degrees to create a second template, and template matching is performed using the second template. The predetermined area is recognized again, and the center of the predetermined area is calculated from a point on the area covering the predetermined area and a point on the second template corresponding to the point when the predetermined area is recognized again. An image recognition method characterized in that: 2. An image recognition apparatus for recognizing a point-symmetric predetermined area in an object by imaging the object, wherein template matching is performed on an image of the object using a first template including the predetermined area. Means for performing the template matching using a second template obtained by cutting out an area covering the predetermined area as a template and rotating it by 180 degrees, and re-recognizing the predetermined area; A point on an area covering the area, and means for calculating the center of the predetermined area from a point on the second template corresponding to the point when the predetermined area is recognized again. Recognition device.