JPH0397079A - Device for detecting center of gravity - Google Patents

Abstract

PURPOSE:To enable a successive processing at real time by extracting the first and final coordinates of effective picture data corresponding to an effective picture pattern in one scanning line and detecting the coordinates of a position for the center of gravity in a contour line pattern based on a cumulated result after scanning is finished. CONSTITUTION:A means 4 is provided to successively acquire th binary picture data of one picture element from the one-scanning line output signal of a picture reading means 1, and an extracting means 5 is provided to extract the first and final coordinates of the effective picture data corresponding to the effective picture pattern in the scanning line. Then, means 5 and 6 are provided to detect the coordinates of the position for the center of gravity in the contour line pattern for the effective picture pattern to be obtained for each scanning line based on the cumulated result of data in this prescribed form corresponding to the coordinates for the center of gravity in the picture pattern after scanning is finished. Thus, since the first and final coordinates of the effective picture data corresponding to the contour line of the effective picture pattern are converted to the prescribed data and cumulated for each line, the successive processing is enabled for each line and a processing to detect the center of gravity can be speedily detected at real time.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a center of gravity detection device, particularly a center of gravity detection device for detecting the center of gravity position of an image pattern scanned by an image reading means in units of l scanning lines each consisting of predetermined pixels. It is related to.

[Prior Art] In various types of image processing, a technique is known in which the position of the center of gravity is detected as a reference point of a certain image pattern.

For example, to position a printed circuit board at a predetermined position on a processing machine? It is known that a printed pattern such as a 3fh circle is formed on a printed circuit board, the center of gravity of this printed pattern is detected as a reference position of the pattern, and this position is positioned at a predetermined position on a processing machine. .

It is known that the position of the center of gravity of a two-dimensional image pattern, that is, a figure, can be expressed using the moment of inertia, considering image density or brightness as mass. When considering the xy orthogonal coordinates that include a certain figure, the coordinates of the center of gravity (xG.yG) are shown as follows. x G = M107 MOO − (
1)yG=MOl/MOO...
・(2) However, M00: Area of figure MLO: First moment of inertia with respect to the y-axis MOI:
The first moment of inertia with respect to the Geometric pattern data is created by binarizing the data. Here, line data assumes logic "l" in areas where figures exist due to binarization, and line data assumes logic "0" in areas where figures do not exist (data is binarized and (The density of the figure is not considered).

Here, it is assumed that the scanning lines are parallel to the X-axis and the line arrangement direction is parallel to the y-axis.

In this case, the l-th moment of inertia MIO with respect to the y-axis is
The address in the line of data that takes the logic rlJ of each scan line (distance from the y-axis to the data point, i.e.
(equivalent to coordinates) can be detected as a value that is sequentially added.

The first-order moment of inertia MOI with respect to the X-axis is determined by calculating the product of the total number of data that takes a logical "l" in a line and the address of that line (corresponding to the distance from the X-axis of the line, that is, the y-coordinate). It can be detected as a cumulative value for each line. Further, the area of a figure can be detected as the sum of (logical "l") data of each line.

The X of the figure obtained in this way. The coordinates (xG.yG) of the center of gravity can be determined from the moment of inertia regarding the y-axis and the area by calculating equations (1) and (2).

In the above processing method, all pixels (material points) in the figure are referred to, so if part of the image data of the figure is missing due to a failure in the figure creation process or image reading process, this The center of gravity position is determined, including the evaluation of the missing part. If the figure originally includes such a missing part, the calculated center of gravity position is the original position and there is no problem.

However, in actual applications, such as positioning a printed circuit board with the aforementioned predetermined printed pattern, the image pattern 20 itself may be missing during the board forming process, or foreign particles such as dust may be present, as shown by reference numeral 2l in FIG. Therefore, some image data may be missing. In FIG. 2, the left and right arrows indicate the direction of the scanning line, and the symbol x. y is X, y
Indicates the direction of the axis.

If the above-mentioned processing method is used in the case shown in FIG. 2, an error will occur in detecting the center of gravity position as the reference position of the printed pattern. Naturally, it goes without saying that this detection error has a negative effect on the accuracy of processing that uses the detection results (positioning of the printed circuit board in the above application).

An object of the present invention is to solve the above problems.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a center of gravity detection method for detecting the position of the center of gravity of an image pattern scanned by an image reading means in units of l scanning lines each consisting of predetermined pixels. The apparatus includes means for sequentially obtaining binarized image data of l pixels from the output signal of the image reading means in units of l scanning lines, and an image sequentially outputted by I pixels from the image data obtaining means. Extracting means for extracting the first and last coordinates of the valid image data corresponding to the valid image pattern in the scanning line based on the data, and the first and last coordinates of the valid image data obtained from the extraction means for each scanning line. Data in a predetermined format is obtained and accumulated, and after scanning is completed, the first and last coordinates of the effective image data obtained for each scanning line based on the cumulative result of the data in the predetermined format are the center of gravity of the contour pattern of the corresponding effective image pattern. We adopted a configuration that includes means for detecting the coordinates of a position as corresponding to the coordinates of the center of gravity of the image pattern. [Operation] According to the above configuration, for each scanning line, predetermined data is formed and accumulated from the first and last coordinates of the effective image data obtained in that line, and after the scanning is completed, the effective image pattern is calculated from the cumulative result. The coordinates of the center of gravity of the outline pattern are detected as the coordinates of the center of gravity of the effective image pattern. At this time, since the first and last coordinates of the effective image data corresponding to the outline of the effective image pattern are converted and accumulated into predetermined data for each line, sequential processing for each line is possible.

[Example] The present invention will be described in detail below based on the example shown in the drawings. FIG. 1(A) shows an example of an actual flow of a center of gravity detecting device employing the present invention. In FIG. 1(A), reference numeral 1 denotes an image reading device such as a video camera. The reading output of the image reading device 1 is the A/D converter 2.
is converted into a multivalued digital signal, and further compared with a predetermined luminance threshold in the binarization circuit 4,
The data is converted into binary data that takes the logic rl or rQJ. The logic rlJ, "0" is associated with the bright and dark parts of the image, respectively. This correspondence may be reversed, but
In the following, it is assumed that the logical "l" is valid image data, and that a certain figure (image pattern) is detected in this portion.

On the other hand, the output of the image reading device l is the address generation circuit 3.
The address of the image data is generated based on the synchronization signal and the like.

The binarization circuit 4 is composed of a counter circuit, etc., and sequentially outputs 1-bit binarized image data corresponding to l pixels in series starting from the first data of the scanning line, and after outputting l lines, it sequentially outputs 1-bit binarized image data corresponding to l pixels. Output the data for the line in the same way.
In synchronization with the l-bit output of the binarization circuit 4, the address generation circuit 3 outputs a set of addresses corresponding to the bits.

This address corresponds to a Cartesian coordinate value, for example the line number (corresponding to the y-coordinate)! 3 and the position of the bit in the line (corresponding to the X coordinate).

The binarized image data and image address signal outputted from the binarization circuit 4 are manually input to the center of gravity parameter detection circuit 5 and the image memory 7. The image memory 7 buffers image data for other image processing, and is conventionally known.

The center of gravity parameter detection circuit 5 includes an address latch circuit 5a,
5bi5 and FIFO memories 5c and 5d. The center of gravity parameter detection circuit 5 operates in units of l scanning lines of data and addresses output from the binarization circuit 4 and the address generation circuit 3.

The structure and function of address latch circuits 5a and 5b are as follows.

First, the address latch circuit 5a receives the first valid image data of the line (1), that is, the first logic rl of the scanning line.
Latch the address of the J bit.

Specifically, the address latch circuit 5a latches the address of data when the data changes from logic "0" to logic "rl" after starting scanning one line. Therefore, the address latch circuit 5a is controlled by the JK flip-flop 1l, which is set by the rising edge of the output of the binarization circuit 4, and the output of the address generation circuit 3, as shown in FIG. 1(B), for example. It can be composed of a data latch l2 that latches.

The JK flip-flop 1l has an address clock clk (
FIG. 1(D) 4th row) is input.

When line data as shown in the lth stage of the waveform diagram of FIG. Set by the first valid data. The NAND gate l3, which receives the output of the binarization circuit 4 and the inverted output Q of the JK flip-flop 11, outputs the latch pulse shown in the third stage in the figure, and the data latch 12 latches the output address of the address generation circuit 3. do. On the other hand, the address latch circuit 5b' stores the last valid image data of the l line, that is, the first logic of the scanning line.
1" bit address is latched. Specifically, the address latch circuit 5b latches the address of the data when the data is logical rlJ during scanning of one line. In the case of the address latch circuit 5b, the address is repeatedly latched until the end of the line every time logic "1" is detected.

Therefore, the address latch circuit 5b includes, for example, a JK flip-flop l5 set by the output of the binarization circuit 4 as shown in FIG. It can be composed of 16, etc.

A clock cLk similar to the JK flip-flop 11 of the address latch circuit 5a is input to the JK flip-flop l5 in FIG. 1(C).

JK flip-flop l5 J. For K input, Fig.
D) As shown in the fifth stage, the output of the binarization circuit 4 is connected to the inverter l.
8, the inverted signal is input manually. In this connection,
JK flip-flop I5 operates similarly to a D flip-flop, and its inverted output is controlled to a high level in synchronization with clock clk at the beginning of each valid image data. As a result, NAND gate l7 enables data latch l6 at the beginning of each valid image data, and the latch data is rewritten. The address latch circuits 5a and 5b detect the switching of the scanning line in synchronization with the change in the line address of the address generation circuit 3.
The final latched addresses are input into the memories 5C and 5d, respectively.

After that, address latch circuit 5a. 5b is reset, and the above process for line l is repeated. In this way,
The addresses of the first and last valid image data of one scanning line are sequentially stored in the FIFO memories 5C and 5d. A CPU 6 consisting of a microprocessor or the like uses these two addresses to calculate the center of gravity position. Note that this address data is the line address (line number) and the address within the data line. The first and last valid image data of each scan line correspond to the actual image as shown in FIG. The left side of FIG. 3 shows the positions of the first and last effective image data of each scanning line obtained by scanning the figure of FIG. 2 shown in the conventional example with the apparatus of FIG. 1(A). As is apparent in FIG. 3, the sequence of positions of the first and last valid image data of each scan line corresponds to the outline of the figure of FIG.

In this embodiment, the center of gravity position is calculated using only the addresses of the first and last valid image data of each scanning line, that is, only the information on the outline of the image pattern.

At this time, data between addresses is not evaluated, and it is assumed that the data consists only of valid data.

As a result, even if the image data actually obtained is missing as shown in Figure 2, and effective data that should have been is missing as shown by the broken line in Figure 1 (D), as shown in Figure 3. The result is the same as processing a complete image pattern with no gaps, as shown on the right.

FIG. 4 shows the center of gravity detection processing procedure. In Figure 4, the CPU
6 and the hardware processing of the centroid parameter detection circuit 5 are shown simultaneously. When 1-bit image data is manually input from the binarization circuit 4, step SL. In S2, Fig. 1(B)
The function of the address latch circuit 5a is executed. Here, when valid image data (logical "l") is detected, that data is latched in step S2, and the remaining line data is processed in steps S3 and subsequent steps. On the other hand, if valid line data is not detected in step Sl, a loop of steps St and S8 is executed until it is detected. If no valid data is entered in the line,
Since valid address data is not latched, the FIFO memory 5c. Address O (invalid address) is stored in 5d, and the process moves to step SlO.

In steps S3 to S5, the function of the address latch circuit 5b is executed. That is, as described above, each time valid data is detected up to the end of the line (step S3), the process of latching the address (step S4) is repeated.

When the end of the line is detected in step S5, step S
6, the addresses of the first and last valid data of the line latched by the address latch circuit 5a are F.
Store in IFO memories 5C and 5d. In step S7, CPtJ6 stores FIFO memory 5c.
Based on the address stored in 5d, the x. Calculate the moment of inertia around the y-axis and the area occupied by the effective image data in the line, and calculate these by (1)
, M 00. in formula (2). Performs arithmetic processing to add MIO and MOI to a counter that accumulates them. The arithmetic processing performed using the addresses of the first and last valid data is as follows.

Here, the address of the data in line l is denoted as Ai, and the addresses of the first and last valid image data are respectively As. Assuming Ae, the first moment of inertia 1 110 of line l around the y-axis (corresponding to the line arrangement direction) is e 1 & 410 = Σ Ai -... (
3) It can be calculated by i=s. That is, by adding the addresses from As to Ae, the first moment of inertia about the line lOy axis can be found. Furthermore, the effective image area twoo for line l is 11JOO = Ae-As+1 =- (4), assuming that 1-bit effective image data has a weight of "l".
is shown. In other words, all data between As and Ae is considered to be valid image data, and the number of pieces of data with a weight of "l" between them is set to 1 100, where the area of the effective image with respect to line l is 1 100. In a line where valid image data is obtained only for pixels, the first and last addresses match, and the area becomes 1.

Also, if the line address (line number) is AI,
The l-th moment of inertia l & l01 of line l around the X-axis (here, it corresponds to the direction parallel to the line) is l MOI = l M00 ・AI ・
− (5).

Thus, line by line, the planes [I MOO and x.
The l-th moment of inertia I MOfI MIO around the y-axis can be obtained, and the CPU 6 stores the area l MGO and x.
The first moment of inertia about the y-axis lMOl. By accumulating l&l1b, the area MOO. x. 3/
First moment of inertia around the axis MOL. MIO can be calculated.

After confirming the completion of the scanning process for one screen in step SlO, the above-mentioned MOO, MLO, MO+
By substituting (1) and (2) into equations (1) and (2), the center of gravity coordinates (xG, yG) of the image pattern can be obtained.

In addition, in FIG. 4, the calculation of the CPU 6 in step S7 is written at a position between steps S6 and 510 for convenience, but in reality, the CPU 6 performs the processing in step s7 in parallel with other processes shown in the figure. Do this.

That is, when the CPU 6 is ready to perform the calculation in step s7, it refers to the flags in the FIFO memories 5c and 5d, and if address data is prepared, it sequentially performs the process in step S7 on the address data.

According to the above configuration, the center of gravity position is calculated using only the addresses of the first and last valid image data of each scanning line, that is, only the information on the outline of the image pattern. Even if some data is missing due to dust or chips, as shown on the left side of Figure 3, the original center of gravity position can be detected accurately. Therefore, even when this center of gravity position is used to control the position of other members, no control error will occur due to the detected error in the center of gravity position. Further, according to the above configuration, there is an advantage that the process of detecting the outline of the image pattern can be executed line by line in real time. In conventional image pattern contour detection processing, it is necessary to once store the image data in memory and then track the boundary between the image pattern and the background. With a simple hardware configuration as shown in D), contour lines can be detected at high speed.
Based on this, it becomes possible to detect the original center of gravity position.

Further, according to the above configuration, the range of threshold values set in the binarization circuit 4 can be expanded.

[Effects of the Invention] As is clear from the above, according to the present invention, in the center of gravity detection device for detecting the center of gravity position of an image pattern scanned by an image reading means in units of l scanning lines each consisting of predetermined pixels, means for sequentially acquiring binarized image data of i pixels from the output signal of the reading means in units of one scanning line; Extraction means for extracting the first and last coordinates of valid image data corresponding to the valid image pattern in the line, and data in a predetermined format from the first and last coordinates of the valid image data obtained for each scanning line from this extraction means. After scanning is completed, the coordinates of the center of gravity of the outline pattern of the effective image pattern corresponding to the entire first and last coordinates of the effective image data obtained for each scanning line are calculated based on the accumulated results of this data in a predetermined format. Since we are looking for a configuration that includes means for detecting the coordinates as corresponding to the coordinates of the center of gravity of the image pattern, for each scanning line, predetermined data can be created from the first and last coordinates of the valid image data obtained in that line. After scanning is completed, the coordinates of the center of gravity of the outline pattern of the effective image pattern are detected from the accumulated results as the coordinates of the center of gravity of the effective image pattern. At this time, the first and last coordinates of the valid image data corresponding to the outline of the valid image pattern are converted and accumulated into predetermined data for each line, so sequential processing in real time for each line is possible, and real-time and High-speed center of gravity detection processing is possible 6 In addition, the center of gravity position of the contour line pattern is detected as the center of gravity of the valid image pattern.In other words, image data within the contour line is ignored, or all image data within the contour line is valid. Since the position of the center of gravity is detected based on the image data, even if there is a defect in the scanned image itself or a defect occurs in the image data during the scanning process due to foreign matter, the original center of gravity position of the target image pattern will be detected. It has excellent effects such as being able to accurately detect

[Brief explanation of drawings]

FIG. 1(A) is a block diagram showing the configuration of a center of gravity detection device using the present invention, and FIG. 1(B) and (C) are FIG. 1(A).
A block diagram showing the configuration of the address latch circuit of
Figure (D) is a waveform diagram showing the operation of the address latch circuit in Figures 1 (B) and (C), Figure 2 is an explanatory diagram of an image pattern including omissions processed by the center of gravity detection device, and Figure 3 4 is an explanatory diagram showing image processing according to the present invention, and FIG. 4 is a flowchart diagram showing a center of gravity detection control procedure. l. Single image reading device 2...A/D converter 3--Address generation circuit 4--Binarization circuit 5--Single centroid parameter detection circuits 5a, 5b...Address latch circuit 5c. 5d-F I FO memory 6...CPU 7...One image memory 1.15--JK flip-flop 2, l6--D clutch 3...NAND gate 7...OR gate 8... Inba's all night madisura, 1,000 translations and written by de n# This is the supply pond mouth Figure 1 (D) accent ef4me fig.3

Claims (1)

[Scope of Claims] 1) A center of gravity detection device for detecting the position of the center of gravity of an image pattern scanned by an image reading means in units of one scanning line made up of predetermined pixels, wherein one scanning line of the image reading means is a unit. means for sequentially obtaining binarized image data of one pixel from the output signal; and effective image data corresponding to the effective image pattern in the scanning line based on the image data sequentially output pixel by pixel from the image data obtaining means. Extracting means for extracting the first and last coordinates of image data; data in a predetermined format is obtained and accumulated from the first and last coordinates of effective image data obtained for each scanning line from this extraction means; The coordinates of the center of gravity of the outline pattern of the corresponding effective image pattern correspond to the coordinates of the center of gravity of the corresponding image pattern, where the entire first and last coordinates of the effective image data obtained for each scanning line based on the cumulative result of data correspond to the coordinates of the center of gravity of the corresponding image pattern. What is claimed is: 1. A center of gravity detection device characterized by comprising means for detecting the center of gravity.