JPS61148303A - Detection of mark center position - Google Patents

Abstract

PURPOSE:To enable easy and accurate detection of a center position of a mark, by displacing a material in X, Y directions with line data difference on two lines as a servo-command which are placed apart by a constant distance in the X, Y directions in the view field of a view field means. CONSTITUTION:In a view field S of a camera 33, lines L1, L2 are set as com puter 30 gate values which are set apart by a constant distance P in the X direction of field S, and a difference of image data on the lines L1, L2 are made as servo-commands in the X direction of the material on which positioning marks are printed. And, lines H1, H2 are set in a similar manner which are set apart by a distance P in the Y direction of the view field S, and the image data difference on the lines H1, H2 are made as servo-commands in the Y direc tion of the material. By displacing the material in X, Y directions by the X,Y direction servo-command to detect the center position of the mark. By this arrangement, the center position of the mark can be detected easily and at a high accuracy.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for detecting the center position of a positioning mark printed on a material using visual means. [Prior Art] Recently, as shown in FIG. 1, a press machine 10 and a material supply device have been combined, and a press punching printing section and a number of positioning marks in the vicinity of the printing section are printed from a material 1 to the printing section. A device for automatically continuous punching has been proposed (
(Japanese Patent Application No. 57-17061)). To briefly explain this device, the material supply device hangs and passes the beam n over the rails 218 and 21b laid on the left and right sides, and as the pole screier B rotates, the beam portion is moved to the rails 218 and 21). 21b (in the Y direction K), a clamper carrier U is suspended from the beam portion, and the clamper carrier U is moved along the beam n (in the X direction). Further, the clamper carrier arm is provided with a clamper (not shown), and serves as a trap so that the material 1 can be clamped. Therefore, this material supply device separates material 1 from X-Y
It can be moved along the upper surface of the table 6 in the X-Y direction. When positioning the material 1 to the press machine 10 using this material supply device, first, the material 1 is supplied in the X-axis direction and the Y-axis direction by the material supply device to the press machine 10 having the camera 1), and then Camera 1) as shown
Rough positioning is performed so that the positioning mark M printed near the press-cutting printed portion of the material 1 is included in the field of view. Subsequently, the material 1 is fed in the X-axis direction (sub-scanning) and is main-scanned in the Y-axis direction with a predetermined field of view V by the visual means. Then, the amount of deviation X in the X-axis direction between the center position Xc of the sub-scanning and the center position C of the reference mark M is calculated as follows:
The sub-scanning position Xa at the time of detection and the reference mark M at the end
The detection is based on the difference between the average value of the detected sub-scanning position Xb and the sub-scanning center position Xc. In addition, the amount of deviation y in the Y-axis direction between the center position Yc of the main scanning and the center position C of the reference mark M is the distance 1) from the upper limit of the field of view to the reference mark M during main scanning. Distance to the lower limit of visual field! , is detected by the average value of the difference. Another method for detecting the center position of a mark in the X direction is to detect the point at which the diameter of a circle mark or the like has a maximum value (Japanese Patent Application No. 102,653/1982). When feeding the material to the punching center W of the press machine 100, the camera

[l and press machine 100 punching center W
Since the positional relationship between the We are trying to supply materials. [Problems to be Solved by the Invention] By the way, in the conventional method of detecting the center position of a mark, there is a possibility that the detection accuracy is slightly poor. That is, the center position of the circle mark in the X direction is detected by detecting the front and rear ends of the circle mark,
In the case of the method of detecting from the average value, even if small image noise is added to the front end or rear end of the circle mark, a detection error will occur due to this. In addition, in the case of the method of detecting the point at which the diameter of a circle mark, etc. has the maximum value, the change in length in the Y direction is very small near the maximum value of the diameter compared to the distance traveled in the X direction. It is difficult to determine the point at which the maximum ° value occurs. The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a method for detecting the center position of a mark by which the center position of a mark can be detected easily and with very high accuracy. [Means for solving the problem] According to the present invention, in the visual field of the visual means,
Two lines L in the Y direction separated by a constant interval P in the direction
, , L, and set the difference between the image data on the line Li and the image data on the line Li as a moving command for moving the material in the Two lines H in the X direction separated by a distance P,
, H2, and the difference between the image data on line 1 and the image data on line 2 is used as a servo command to move the material in the Y direction by moving the material in the X and Y directions. The center position of the mark is detected. [Operation] When the image data on two lines separated by a certain distance P in the visual field where the mark is captured are both equal, the positioning of the mark in the visual field means in the direction perpendicular to the line is completed; As a result, the center position of the mark is detected. [Example] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. First, the present invention will be explained in principle using FIG. Now, if we assume that a matrix camera is used as a visual means, two images are displayed at regular intervals P in the field of view S of the camera.
Set book lines Li, L, . Then, the analog output of each detection bit of the sensor on each line is converted into digital multi-value data, and the sum of the data is calculated. Next, the sum is ri, L, and ■凰 for each. If v, then v,, the difference between 2v and 2v ΔV, ΔV=V, -V
. is calculated, this data ΔV is converted from digital to analog, and this is used as a servo command for moving the material in the X direction. As a result, the material is positioned so that Δ■=0. In the above manner, a small change in X causes a large change in Δ■, and since the analog output of each bit of the sensor is multi-valued, highly accurate positioning can be achieved. Note that binarization may be used depending on the required accuracy; in this case, the above V,
, V! corresponds to the length of the line that overlaps the mark. Also, when positioning in the Y direction, similarly to the above, two lines H1, L! are placed at a constant interval P! is set, the analog output of each detection bit of the sensor on each line is digitalized into multi-values, and the sum of the notators is calculated. The sum is H
te W1 for each of l and H. W = W, W1 = W, difference ΔW, -W. is calculated, this data ΔW is converted from digital to analog, and this is used as a servo instruction to move the material in the Y direction. FIG. 4 is a block diagram schematically showing an apparatus for carrying out the method of the present invention. In the figure, a computer (9
) is the gate value, or L! is output to the gate signal generation circuit 31, and the gate value H1 or H! is output to the arithmetic circuit proverb. The camera scans the image area where the image is formed, obtains a video signal, synthesizes this video signal with a synchronization signal that is applied from the synchronization signal generation circuit, and converts the video composite signal into an A/D converter. Output to. The A/D converter converts the input analog signal into a digital signal and outputs it to the arithmetic circuit and latch circuit. In addition, the synchronization signal generation circuit a, horizontal synchronization signal,
A vertical synchronization signal is output to the gate signal generation circuit 31 and the arithmetic circuit 32. The gate signal generation circuit 31 is composed of a comparator 31), a counter 312, and a flip-flop 313, as shown in FIG. The counter 312 is reset by the horizontal synchronizing signal pressure, counts the video clock that scans the image part of the camera, and outputs this count value to the comparator 31). The comparator 31) has a gate value added to the other input by the computer, and when these two human input values match, it outputs a match signal V to the combiator addition and latch circuit 36. The latch circuit latches the digital video data according to the coincidence signal V, and the combinator I inputs the latch data when the coincidence signal V is input. Further, when the coincidence signal V is applied to the computer chrysanthemum, the output of the gate value is switched from Ll to Ll. Flip-flop 313 is set by the vertical synchronization signal, outputs the processed signal to the combiator, and is reset by the CPU acceptance signal from combiator I. Also, a calculation circuit! is the comparator 321 as shown in FIG.
, a counter 322, a calculator 323, and an AND circuit 324. The counter 322 is reset by the vertical synchronization signal, counts the horizontal synchronization signal, and outputs this count value to the comparator 321. The comparator 321 has a gate value H3 or H2 added from the combinator I to its other input, and outputs a match signal H to the AND circuit 324 and the computer I when these two input values match. The AND circuit 324 is enabled to operate by the coincidence signal H, adds the other input video clock to the integrator 323, and
The integrator 323 integrates the digital video data added from the A/D converter in synchronization with the video clock, and outputs this integrated value W to the computer I. In addition, integrator 3
23 is reset by the horizontal synchronization signal. Next, the processing procedure of the combinator (9) will be explained according to the flowcharts of FIGS. 7 and 8. ! Figure 7 shows the positioning process of the material in the X direction.
First, the computer determines whether a processed signal has been input from the gate signal generation circuit 31 (step 101).
. If no processing signal is input, that is, the CPU
From the generation of the acceptance signal until the generation of the vertical synchronization signal, it is determined whether or not the coincidence signal (2) has been input from the gate signal generation circuit 31 (step 102). If the coincidence signal ■ is not input, the process returns to step 101 according to the flow line 103, and if the coincidence signal V is input, the process proceeds to step 104. In step 104, it is determined whether the flag is 0 or not. If it is 0, the process proceeds to step 105, and if it is not O, the process proceeds to step 106. In step 102, it is determined whether the horizontal scanning position is on the preset line L1 or Lt, and in step 104, it is determined whether the position is above or above the line L1. Here, flag 0
means on line H8, and flag 1 means on line Ll. Step 105 adds the digital video data latched by the coincidence signal (2) to (2). That is, here, the digital video data on line H8 is integrated. Thereafter, the flag is set to 1 (step 107), and the process returns to step 101 according to flow line 03. Similarly, step 106 adds the digital video data latched by the match signal V to V, and then resets the flag to O (step 108) and returns to step 101 according to flow line 103. In this way, by repeating the above operation until a vertical synchronization signal is generated, the preset line L. Then, the integrated values v1 and v2 of only the upper data are obtained.Next, the vertical synchronization signal is generated. When the computer I inputs the processed signal from the gate signal generation circuit 31, it executes a difference calculation to obtain the difference ΔV (=V, -■,) between the integrated values v1 and vt (step 109).This difference ΔV is It is output as a servo command to move the material in the X direction.Subsequently, vl and v2 are each reset to O (step 1) 0), and the flag is also reset to 0 (step 1) 1). With the above, one process is completed. And the difference Δ
The above process is repeated until V becomes 0. FIG. 8 shows the positioning process of the material in the Y direction, and the concept is exactly the same as in the case of the X direction described above. However, in the Y direction, since the data is for lines H, , H, in FIG. 3, processing becomes difficult in a normal television camera because the cycle of each bit output in the horizontal line direction is very short. In FIG. 8, the computer first determines whether a processed signal has been input from the gate signal generation circuit 31 (step 201). If no processing signal is input,
It is determined whether a coincidence signal H has been input from the arithmetic circuit 32 (step 202). If the coincidence signal H is not input, the process returns to step 201 according to flow line 203, and if the coincidence signal is input, the process proceeds to step 204. In step 204, it is determined whether the flag is 0 or not. If it is 0, the process proceeds to step 205, and if it is not 0, the process proceeds to step 206. Note that flag O means on line H8, and flag 1 means on line H1. In step 205, the integrated value W of the digital video data on the line H3 to which the coincidence signal H is output is manually input from the arithmetic circuit, and this is set as W. Thereafter, the flag is set to 1 (step 207), and the process returns to step 201 according to the flow line 203. Similarly, in step 206, the integrated value W of the digital video data on the line H8 on which the coincidence signal H is output is inputted from the arithmetic circuit 32, and this is sectored as WL. In this way, until the vertical synchronization signal is generated,
The integrated value W1 of the digital video data on lines H, ,H on that screen. W is set. Next, when the computer inputs the processed signal from the gate signal generation circuit 31 due to the generation of the vertical synchronization signal, it executes a difference calculation to obtain the difference ΔW (=W, -Ws) between the integrated values W1 and W2 (step 208). This difference ΔW is output as a servo command for moving the material in the Y direction. Next, the flag is reset to 0 (step 209),
One process is completed. Then, the above process is repeated until the difference ΔW becomes 0. As described above, the center of the mark on the material can be positioned with high precision at the center position of the camera's field of view, and the center position of the mark can also be detected with high precision from the coordinate values of the X-Y table 5 at this time. can. [Effects of the Invention] As explained above, according to the present invention, the center position of a mark can be detected easily and with very high precision.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an outline of a material supply device and a press machine to which the method of the present invention is applied, Fig. 2 is a diagram used to explain the operation of conventional visual means, and Fig. 3 is a diagram showing the method of the present invention. FIG. 4 is a block diagram schematically showing an apparatus for carrying out the method of the present invention. FIG. 5 is a block diagram showing details of the gate signal generation circuit shown in FIG. 4. Figure 6 is a block diagram showing details of the arithmetic circuit in Figure 4;
8 and 8 are flowcharts showing the processing procedure of the computer in FIG. 4, respectively. 1...Material, 10...Press machine, 1), 33.
...Camera, processing material supply device, δ...X-Y table, processing...combiator, 31...gate signal generation circuit, 32...arithmetic circuit, ah...synchronization signal generation Circuit, ah... A/D conversion circuit, ah... latch circuit. Figure 4 S0 Figure 6 Figure 7

Claims (3)

[Claims] (1) Move the material on which the positioning mark is printed in the X and Y directions on the X-Y table, capture the mark with a visual means placed at a predetermined position, and determine the center position of the mark The method includes setting two lines L_1 and L_2 in the Y direction that are spaced apart by a fixed interval P in the X direction of the visual field in the field of view of the visual means, and image data on the line L_1 and image data on the line L_2. The difference between the image data and the image data of the material is set as the servo command in the X direction of the material, and similarly, two lines H_1 and L_2 in the X direction separated by a constant interval P are set in the Y direction of the field of view, and the A mark characterized in that the center position of the mark is detected by moving the material in the X and Y directions using the difference between the image data and the image data on line H_2 as a servo command for the material in the Y direction. How to detect the center position of. (2) The mark center position detection method according to claim (1), wherein the positioning mark is a circle mark, and the constant interval P is approximately 0.8 times the diameter of the circle mark. (3) The image data on the line is the sum of data obtained by digitally converting or binarizing the analog output of each detection bit on the line of the visual means. How to detect the center position of the mark described.