JPH06331312A - Detection of center position of target mark by image processing - Google Patents

Abstract

PURPOSE:To accurately measure the center of a target by edge measurement by scanning the interior of a target mark binarized from the center of a cursor at every one pixel in one of X- and Y-axis directions. CONSTITUTION:The target mark 11 for drilling provided on a work is photographed and a variable density image signal is binarized in an image processing part to scan the center of a cursor at every one pixel in an X- or Y-axis direction to obtain a white and black reversal coordinate value and the edges a1, a2 in the X- or Y-axis direction are measured on the basis of the coordinate value. Next, on the basis of the white and black reversal coordinate value obtained by scanning the middle point coordinate values of the edges a1, a2, edges b1, b2 in the axis direction are measured. Subsequently, on the basis of the white and black reversal coordinate value obtained by scanning at every one pixel pitch, edges a1', a2' are measured and the diameter reference values in the X- and Y-axis directions of the mark 11 stored in a memory part are fitted to the distance between the edges b1, b2 and the distance between the edges a1', a2' and the middle point coordinate position of the edges b1, b2 is set in the center of the mark 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a target mark center position detection method by image processing for detecting the center position of a target mark for perforation provided on a plate material such as a printed circuit board by a desired means such as printing.

[0002]

2. Description of the Related Art Since a reference hole is formed in a printed circuit board or the like, target marks printed with copper foil are provided at four corners, and the printed circuit board is provided with a moving mechanism so that each target mark is located immediately below a photographing section. The center of the target mark is measured by a predetermined means while being moved through, and the drill is moved by X and Y by an amount of error from the measured center.
Fine movement (correction movement) in the X-axis and Y-axis directions via the axis feed mechanism to align the center of the drill with the center of the target mark, and then raise the drill in the Z direction from that position to center the target mark. A reference hole having a hole core is drilled. By the way, the reference hole is used as a reference for printed wiring on a printed circuit board, etc., and it is necessary to accurately form a hole at a theoretical position. Conventionally, the center of the target mark is A / D for the grayscale image signal of the target mark photographed by the photographing unit.
The conversion unit converts the signal into a digital signal, the image processing unit converts it into a binary signal, displays it on a monitor (CRT), and obtains it by measuring the center of gravity by a dynamic window method.

[0003]

However, in the case of measuring the center of gravity, when the pattern other than the target mark is converted into black and white by binarization, the black and white conversion coordinate system is greatly affected, and the center of the target mark cannot be accurately measured. The problem arises.

The present invention has been made in view of the conventional circumstances, and its object is to provide a method for detecting the center position of a target mark by image processing for accurately measuring the center of the target mark by edge measurement. is there.

[0005]

[Means for Solving the Problems] The technical means taken to achieve the above object is to photograph the target mark of a workpiece provided with a target mark for perforation with a photographing section,
The grayscale image signal is binarized by the image processing unit, the binarized data is displayed on the monitor screen, and when the center of the cursor is in the binarized data of the target mark, the cursor center is on the X-axis direction or the Y-axis. A black-and-white inverted coordinate value obtained by scanning one pixel pitch in a direction, and edges 1 and 2 in that direction.
Is measured first, and then the black and white inverted coordinate values obtained by scanning the midpoint coordinate positions of the edges 1 and 2 in the other axis direction by one pixel pitch are measured for the edges 1 and 2 in the axis direction. Then, the edge points 1'and 2'are obtained by black-and-white inverted coordinate values obtained by scanning the midpoint coordinate position of the edges 1 and 2 in the direction parallel to the edge points 1 and 2 with the one pixel pitch. The diameter reference values in the X-axis and Y-axis directions of the target mark measured and stored in the storage unit are matched with the distance between the edges 1 and 2 and the distance between the edges 1'and 2 ', and the edges 1 and 2 are matched. The gist is that the center point coordinate position of is the center of the target mark.

[0006]

According to the above technical means, the black-and-white reversal coordinate system of the target mark is scanned from the center of the cursor to, for example, one pixel pitch in the X-axis direction, and the edge in the X-axis direction is measured by the obtained black-and-white conversion coordinate value. First, the midpoint is obtained, and the midpoint is centered in the X-axis direction of the target mark. Using this as a reference point, scanning is performed for one pixel pitch in the Y-axis direction, and edge measurement in the Y-axis direction is performed using the black-and-white inverted coordinate values, as described above.
Thus, the distance between the edges of the target mark in the Y-axis direction, that is, the diameter in the Y-axis direction is obtained. Then, the middle point (hypothetical center) is scanned for one pixel pitch in the X-axis direction this time, and the edge measurement in the X-axis direction is performed with the black-and-white inverted coordinate value.
By this, the distance between the edges in the X-axis direction, that is, the diameter in the X-axis direction is obtained. Finally, the result of collation between the X-axis and Y-axis direction diameter reference values of the target mark stored in the storage unit and the above-described X-axis direction edge distance and Y-axis direction edge distance (measured diameter). It is determined that the target mark has a regular area only when it fits within the reference range (allowable range) of the diameter reference value, and the assumed center is determined as the actual center.

[0007]

As described above, according to the present invention, the target mark binarized from the cursor center is scanned by one pixel pitch in one direction of the X-axis or the Y-axis and black-and-white inversion is performed by the black-and-white inversion coordinate value. Direction edge (X-axis or Y-axis direction edge) is measured, the middle point is used as a reference point, and the reference point is scanned in the other direction of the X-axis or Y-axis by one pixel pitch, and black-and-white inversion is performed in the same manner. The edge in that direction is measured with the black and white reversal coordinate value, and the midpoint is set as the hypothetical center, and the hypothetical center is again scanned in the same direction by one pixel pitch to perform the black and white reversal coordinate value. The edge of the target mark (Y-axis or X-axis edge) is measured and collated with the diameter reference value in the storage unit, and the assumed center is the center of the target mark. Or misidentify It is possible to reliably detect the center position of the target mark without.

[0008]

Embodiments of the present invention will now be described with reference to the drawings. 1 to 3 show a first embodiment of a method of detecting the center position of a target mark by image processing according to the present invention, and FIGS. 4 and 5 show a second embodiment of the same. First, the first embodiment will be described.

FIG. 1 shows an apparatus for executing the center position detecting method of this embodiment, FIG. 2 shows an edge measurement state, and FIG. 3 shows a flow chart. In FIG. 1, reference numeral 1 is a printed circuit board to be punched, and target marks 11 for punching reference holes are provided at four corners. This target mark 11 is made by printing copper foil and has a diameter of 1 m.
The target mark 11 can be moved by automatic control so that the target mark 11 is located immediately below the camera unit 3, that is, the camera.

Reference numeral 2 denotes an image processing unit, which is an image for performing arithmetic processing such as binarization on video information (video information of a grayscale image signal) converted into a digital signal by an A / D converter (not shown). The processing circuit 12, an image memory 22 for storing the binarized data thereof, a central processing unit 32 for executing a predetermined control program, a storage unit 42 for storing necessary data for the central processing unit 32, and the like. Is provided, and the grayscale image signal of the target mark 11 is binarized by the image processing circuit 12,
It can be written in the image memory 22.

Reference numeral 4 denotes a monitor, which displays the image in the image memory 22 and scans its coordinate system in the X and Y axis directions described later.

In the above scanning, the center of the cursors 13 and 13 is located at an arbitrary portion of the binarized data (binarized data of the target mark) in the image memory 22 binarized by the image processing circuit 12.
X from the center 13 'of the cursor 13, 13 when 13' is located
-1 by scanning one pixel pitch in one direction of the axis or Y-axis
Alternatively, the coordinate value for black-and-white conversion to 1-0 is detected as the edge in that direction, and the pixel is scanned from the midpoint coordinate position of the edge in the other axis direction by one pixel pitch and 0-1 or 1-
The coordinate value for black-and-white conversion to 0 is detected as an edge in that direction, and further, from the midpoint coordinate position (assumed center) of the edge, scanning is similarly performed for one pixel pitch in the above-mentioned one direction, and 0-1 or 1-0. The coordinate value for black and white conversion is detected as an edge in that direction.

The central processing unit 32 sequentially executes the control programs shown in the flowchart of FIG.

Next, the method for detecting the center position of the target mark by image processing in this embodiment will be described in detail with reference to the above scanning and the drawings (FIGS. 2 and 3). First, the printed circuit board 1 is moved and set so that the target mark 11 is located directly below the photographing unit 3, and the grayscale image signal photographed by the photographing unit 3 is binarized by the image processing circuit 12 and stored in the image memory 22. It is written and the binarized data is displayed on the monitor 4. At this time, it is determined whether the center 13 'of the cursors 13, 13 is located within the binarized data of the binarized target mark 11. First, the center 13 'of the cursor 13, 13 is 2
If the binarized target mark 11 is not in the black-and-white conversion coordinate system (considering that the target mark 11 is not photographed due to improper movement of the target mark 11 directly under the photographing unit 3), error processing is performed. , Cursor 13, center of 13 1
When 3'is in the black-and-white conversion coordinate system, the center 13 'is scanned in the X-axis direction by one pixel pitch, and 1-0 or 0-
One edge X1 (a1) is detected by the coordinate value for black-and-white conversion to 1. When the detection of the edge X1 is completed, the center 13 'is scanned in the opposite direction in the X-axis direction by one pixel pitch, and black-and-white conversion is performed in the same manner as above. . Next, the midpoint coordinate position of the edges X1 and X2 is stored in the storage unit 42, that is, the RAM as the center of the X axis of the target mark 11. Then, the target mark 11 is scanned on the midpoint coordinate positions of X1 and X2 in the Y-axis direction by one pixel pitch to scan the edges Y1 (B1) and Y2.
(2) is detected, and the midpoint coordinate position (hypothesized center O) is stored in the storage unit 42. Next, the edge Y
Edge X1 'is a black-and-white conversion coordinate value that scans on the midpoint coordinate position of 1 and Y2 in the X-axis direction by one pixel pitch and performs black-and-white conversion.
(A1 ') and X2' (A2 ') are detected. Further, the diameter reference value and the distance between the edges Y1 (b1) and Y2 (b2) stored in the storage unit 42 by teaching and the edge X1 '.
If the distance between both edges is matched with the reference range (allowable range) of the diameter reference value by comparing the distance between (a1 ') and X2' (a2 '), the edge Y1 (b1), Y2 (b2) ) The center point coordinate value (assumed center O) is recognized as the center of the target mark 11, and if the distance between both edges is out of the reference range (allowable range) of the diameter reference value and does not match, the target mark
Error processing is performed on condition 11 that the size and shape are not proper.

As a result, the center position of the target mark 11 printed with a regular area and shape in plan view can be obtained by edge measurement.

By the way, the result is given to the X / Y-axis driver circuit 6 which is an external device through the I / O port 5, and the X / Y driver circuit 6 feeds the feed amount of the X / Y-axis feed mechanism 7. Is controlled to feed the punching tool 8 (drill) directly below the center O of the target mark 11 and the Z-axis feed mechanism 9 including a solenoid and an air cylinder moves the punching tool 8 up to raise the reference hole. Perforate (not shown).

Next, the second embodiment shown in FIGS. 4 and 5 will be described. In this embodiment, the center Y of the target mark 11 obtained by the edge measurement of the first embodiment is used as a provisional center for the edge Y1 ( Open a window 10 that is slightly larger than the distance between 1) and Y2 (2) and the distance between edges X1 '(1') and X2 '(2'), and that window
The center of gravity of four monitor screens in 10 areas is measured to pursue a more accurate center of the target mark 11. Of course,
The outside of the window 10 range is masked and excluded from the measurement range.

In the above-described embodiment, the scanning is started by scanning the center 13 'of the cursors 13, 13 in the X-axis direction by one pixel pitch, but conversely, the center 13' is moved in the Y-axis direction. 1
The pixel pitch may be scanned and detected from the edge Y1. In this case, X and Y in the flowcharts shown in FIGS. 3 and 5 are simply replaced with each other, and therefore the flowcharts are omitted.

[Brief description of drawings]

FIG. 1 is a block diagram of an apparatus for performing a target mark center position detecting method by image processing according to a first embodiment.

FIG. 2 is a state diagram of edge measurement showing a three-way relationship between a monitor screen, binary data, and a cursor.

FIG. 3 is a flowchart of the first embodiment.

FIG. 4 is a state diagram of the center of gravity measurement showing the four-way relationship between the monitor screen, the binarized data, the cursor, and the window of the second embodiment.

FIG. 5 is a flowchart of the second embodiment.

[Explanation of symbols]

11: Target mark 1: Work (printed circuit board) 4: Monitor 3: Imaging unit (camera) 13, 13: Cursor 13 ': Cursor center 2: Image processing unit 42: Storage unit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H05K 13/08 A 8315-4E

Claims (1)

[Claims] 1. The target mark of a workpiece provided with a target mark for punching is photographed by a photographing unit, the grayscale image signal is binarized by an image processing unit, and the binarized data is displayed on a monitor screen. , X on the cursor center when the cursor center is in the binarized data of the target mark
The black and white inverted coordinate values obtained by scanning one pixel pitch in the axial direction or the Y-axis direction are first used to measure the edges 1 and 2 in that direction, and then the other points on the midpoint coordinate position of the edges 1 and 2 are measured. The edges b and b in the axial direction are measured with the black and white inverted coordinate values obtained by scanning the pixel in the axial direction at 1 pixel pitch, and the edges a and b are located on the midpoint coordinate position of the edges b and b. Edges 1'and 2'are measured with black-and-white reversal coordinate values obtained by scanning the pixel pitch in the direction parallel to 2, and the diameter reference of the target mark stored in the storage unit in the X-axis and Y-axis directions. A target mark characterized in that the value and the distance between the edges 1 and 2 and the distance between the edges 1'and 2'are matched so that the midpoint coordinate position of the edges 1 and 2 is the center of the target mark. Center position detection method.