JP2929719B2 - Measurement device for parts position - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique applied to mounting an electronic component such as an IC having a plurality of pins at an appropriate position on a printed circuit board, for example. For example, the present invention relates to a component position and other measuring device suitable for measuring the holding position and posture of an electronic component held by a chip mounter.

[0002]

2. Description of the Related Art When an IC such as a QFP (hereinafter simply referred to as "IC") is mounted on a printed circuit board by a chip mounter, each pin of the IC is correctly positioned on a corresponding pattern on the printed circuit board. It is necessary to mount an IC. Therefore, when the chip mounter picks up the IC, it determines whether or not the holding position and posture are appropriate, and corrects the holding posture and mounting position of the IC according to the result of the determination, and corrects the IC on the printed circuit board. Has been implemented.

Conventionally, an image processing apparatus has been used for this type of position / posture determination. An IC held by a chip mounter is imaged by a camera at a predetermined observation position, and the input image is sent to the image processing apparatus. After capturing and binarizing the image, the center of gravity and the rotation angle are calculated from the binary image to measure the position shift state, and the above correction processing is performed using the measurement result.

[0004]

However, in the case of the above method, if the calculation of the center of gravity and the rotation angle is performed by software processing,
It takes time to measure the position and orientation of the component, and if hardware processing is performed, the hardware configuration becomes complicated and the cost increases.
In the IC, the dimensions of the pins are properly controlled.
Since the outer shape of the package portion has poor dimensional accuracy, there is a problem that the measurement accuracy of the center of gravity and the rotation angle is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and can measure the position and orientation of a component at a high speed with a simple circuit configuration, and at a high precision without being affected by the accuracy of the external dimensions of the package. It is an object of the present invention to provide a measuring device for measuring the position and the like of a part capable of measuring the position and orientation of the part.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a component position measuring device for capturing a component having a plurality of pins and measuring a component position and orientation from an input image of the component. Means for processing to generate a binary image;
After scanning the value image in a fixed direction and detecting the tip position of an arbitrary pin, the center of gravity of the tip of the pin is measured from the tip position, and the tip of the adjacent pin is sequentially determined based on the center of gravity position. Means for measuring the position of the center of gravity.

[0007]

Since the position of the center of gravity of each pin is sequentially measured from the position of the end of an arbitrary pin detected by scanning the binary image, the binary image of the component is obtained from the position of the center of gravity of each pin. The center of gravity and the rotation angle of can be easily measured. In addition, the measurement accuracy of the center of gravity and the rotation angle is improved because the measurement is not affected by the dimensional accuracy of the outer shape of the package portion or the quantization error. Moreover, the quality of the pitch between the pins can be determined based on the distance between the centers of gravity of the tips of the pins.

[0008]

FIG. 1 shows an embodiment of an apparatus for measuring the position of parts 1 according to an embodiment of the present invention. In the figure, 2 is I
C, a plurality of pins 4 protrude along the outer periphery of the rectangular package portion 3. The IC 2 is located on the tray 5 and the suction portion 6 of the chip mounter
2 is sucked up, transported to the position of the printed circuit board 7, and mounted at a predetermined position on the printed circuit board 7.

An observation position is set during the transportation of the IC2,
The measuring device 1 such as a component position is installed at the observation position, and it is inspected whether the holding position and the posture of the IC 2 by the suction unit 6 are appropriate. If the holding posture is inclined, the suction unit 6 is rotated in the direction shown by the arrow a by the inclination of the rotation angle to correct the holding posture, and if the holding position is displaced from the reference position, The mounting position on the printed circuit board 7 is corrected by the positional shift amount.

The measuring device 1 for measuring the component position and the like is constituted by a camera 9 and an image processing device 10. The camera 9 is arranged below the observation position and images the IC 2 from below. Although not shown, it is a matter of course that an illumination device is provided above or below the observation position to perform transmission illumination or reflection illumination.

FIG. 2 exemplifies a circuit configuration of the image processing apparatus 10. The image input unit 11 receives an analog image signal from the camera 9, binarizes the image signal, and outputs the binary image to the image memory 12. The image memory 12 stores the input image data of the binary image in units of one pixel. The character memory 16 stores font data for characters to be displayed on the video monitor 14. The image output unit 13 converts the image data output from the image memory 12 and the character memory 16 into a signal of an analog amount, and sends an image signal for one screen to the video monitor 14. The video monitor 14 displays an input image, a calculation result, and the like based on an image signal from the image output unit 13.

The image memory 12 and the character memory 16 are connected to an address / data bus 17, and the address / data bus 17 has a CPU 18, a ROM 19, and a RAM.
20 and the I / O port 21 are connected to form a microcomputer. In this microcomputer, the CPU 18 decodes and executes a program stored in a ROM 19, reads and writes data from and to a RAM 20, and measures a holding position and a holding posture of the IC 2, for example.
Execute various image processing. The timing control unit 15
The image input unit 11 and the image memory 1 are linked with the CPU 18.
2. It outputs a timing signal for controlling the input and output of data in the image output unit 13 and the character memory 16.

FIG. 3 shows an IC stored in the image memory 12.
In the figure, a hatched portion is, for example, a black pixel, and other portions are white pixels. In order to measure the holding position and holding posture of the IC 2, first, the binary image 22 is scanned in a direction indicated by an arrow b in the figure to detect a black pixel at a tip position P 0 (X 0, Y 0) of an arbitrary pin 4 a. After that, the center of gravity of the tip of the pin 4a is measured from the tip position P0 by the method described in detail below, and the center of gravity of the tip of the adjacent pin is sequentially measured based on the center of gravity.

FIGS. 4 to 7 show a method of measuring the position of the center of gravity of the tip of each pin. FIGS. 8 and 9 show the procedure for measuring the IC holding position and holding posture by the CPU 18 based on this measuring method. Is shown. Hereinafter, the measurement procedure of FIGS. 8 and 9 will be described in detail based on the specific examples shown in FIGS.

In step A of FIG. 8 (indicated by "STA" in the figure), the position of the center of gravity of the tip of each pin is measured by sequentially executing the procedure of FIG. 9 (steps 1 to 15). In step 1 of FIG.
Is set to 0, and in the next step 2, the image memory 1
The binary image 22 stored in 2 is scanned in the direction indicated by the arrow b in FIG. 3, and in step 3, the first black pixel is detected as the tip position P0 of any pin 4a. The coordinates of the tip position P0 are set to (X0, Y0) and stored in the RAM 20 (step 4).

In the next step 5, the CPU 18
A window W1 passing through the front end position P0 is set as shown in FIG. 7, a center of gravity G1 of the front end of the pin 4a included in the window W1 is measured, and its coordinates (XG1, Y
G1) is stored in the RAM 20 (step 6).

In the next step 7, as shown in FIG.
A position Q (XG1 + d1, YG1) shifted by the pin pitch d in the positive direction of the X axis from the center of gravity position G1 is determined, and whether or not the pixel at the position Q is a black pixel, that is, whether or not the pixel is a pin constituent pixel Is determined (step 8). In the case of this example, since the determination is “YES”, the process proceeds to step 9 to obtain a position R (XG1 + d1, YG1 + d2) moved from the position Q by a predetermined distance d2 in the Y-axis direction.
A window W2 passing through the position R and including the tip of the pin 4b therein is set.

In the next step 10, as shown in FIG. 6, the CPU 18 scans the window W2 in the direction indicated by the arrow c, and in step 11, detects the first black pixel as the tip position P1 of the pin 4b. . This tip position P1
Are stored as (X1, Y1) in the RAM 20 (step 12).

Thereafter, the CPU 18 sets a window W1 passing through the front end position P1 as shown in FIG. 7, measures the center of gravity G2 of the front end of the pin 4b included in the window W1, and calculates the coordinates (XG2 , YG2) to RA
It is stored in M20 (steps 5 and 6). Then, it moves from the center of gravity position G2 in the X-axis direction by the pitch d of the pin,
By performing the same procedure as described above, the position of the center of gravity of the tip of the adjacent pin is sequentially measured.

In the process of tracking the position of the center of gravity, when the end pin is moved by the pitch d of the pin in the positive direction of the X axis from the position of the center of gravity of the end pin, the pixel at the moved position is determined to be a white pixel. 8 to step 13
U18 determines whether the flag F is 0 or not. In this case, since the determination is "YES", the process proceeds to step S14.
The CPU 18 sets the flag F to 1, obtains a position shifted by the pin pitch d in the negative direction of the X-axis from the initial center-of-gravity position G1, and repeatedly executes the same procedure as described above in the opposite direction. The position of the center of gravity of the tip position of the adjacent pin is sequentially measured.

Thus, in the process of tracking the position of the center of gravity in the opposite direction, when the center pin is moved from the center of gravity of the end pin by the pitch d of the pin in the negative direction of the X-axis, the pixel at the moved position is determined to be a white pixel. And the process proceeds from step 8 to step 13, where the CPU 18 determines whether or not the flag F is 0. In this case, the determination is “NO” and the CPU 18
Completes the process of measuring the position of the center of gravity of the tip of each pin for one side. The center of gravity of the tip of each pin is measured in the same manner for the other three sides, and the description is omitted here.

Returning to FIG. 8, when the positions of the centers of gravity of the tips of the four sides are measured in step A, the determination in step B becomes "YES", and the CPU 18 determines the centers of gravity of all the pins. IC binary image 22 using position coordinates
Of the center of gravity (step C) and the calculation of the rotation angle (step D).

In this case, any method may be used to calculate the position of the center of gravity and the rotation angle. In this case, the average value of the coordinates of the positions of the centers of gravity of the tips of all the pins is obtained as the position of the center of gravity of the binary image 22. . A position (XM1, YM1) obtained by averaging the coordinates of the center of gravity of the tip of the upper pin, and a position (XM2, YM2) obtained by averaging the coordinates of the center of gravity of the tip of the lower pin. Is obtained, and its inclination is obtained as the rotation angle of the binary image 22. Furthermore, by determining the distance between the positions of the centers of gravity of the tips of adjacent pins, it is possible to determine the quality of the pitch of each pin.

[0024]

As described above, according to the present invention, when a component having a plurality of pins is imaged and the component position and orientation are measured from the input image, a binary image of the input image is scanned and an arbitrary pin is scanned. After detecting the tip position, the center of gravity of the tip of the pin is measured from the tip position, and the center of gravity of the tip of the adjacent pin is sequentially measured based on the center of gravity position. The position and orientation of the component can be easily measured from the position of the center of gravity of the tip of each pin. In addition, since there is no influence of the dimensional accuracy of the outer shape of the package part of the component or the influence of the quantization error, the measurement accuracy of the position and orientation of the component is also improved.
Moreover, the remarkable effect of attaining the object of the invention is achieved, for example, the quality of the pitch between the pins can be determined from the distance between the centers of gravity of the tips of the pins.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an implementation state of a component position etc. measuring device according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a circuit configuration of the image processing apparatus.

FIG. 3 is an explanatory diagram showing a binary image of a component.

FIG. 4 is an explanatory diagram showing a method of measuring the position of the center of gravity of the tip of the pin.

FIG. 5 is an explanatory diagram showing a method of measuring the position of the center of gravity of the tip of the pin.

FIG. 6 is an explanatory diagram showing a method of measuring the position of the center of gravity of the tip of the pin.

FIG. 7 is an explanatory diagram showing a method of measuring the position of the center of gravity of the tip of the pin.

FIG. 8 is a flowchart showing a procedure for measuring a holding position and a holding posture of an IC.

FIG. 9 is a flowchart showing a procedure for measuring the position of the center of gravity of the tip of the pin.

[Description of Signs] 1 Component position etc. measuring device 2 IC 9 Camera 10 Image processing device 11 Image input unit 18 CPU

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01B 11/00-11/30 H05K 13/04

Claims (1)

(57) [Claims] An apparatus for measuring a component position and orientation from an input image of a component having a plurality of pins by capturing an image of the component, wherein the input image is binarized to generate a binary image Means for scanning the binary image and detecting the tip position of an arbitrary pin, measuring the center of gravity of the tip of the pin from the tip position, and sequentially determining the center of gravity of the adjacent pin based on the center of gravity position. A part position measuring device comprising means for measuring the position of the center of gravity of the tip.