JPH04332199A - Part mounting apparatus - Google Patents

Abstract

PURPOSE:To prevent drop of IC gravity detecting speed by forecasting a region in which IC leads required for calculating the gravity center exist and then detecting leads through scanning of only such region and then improve lead detection accuracy and gravity measuring accuracy through the interporation processing of video data. CONSTITUTION:A region in which IC and IC leads are forecasted to be existing among the IC imaging data, namely the video data stored in a video memory is calculated with a recognition region calculating means 12. The center coordinates in the four directions of IC are calculated only for such region with an IC lead detecting means 15 by interporation process of the video data stored in the video memory 14, while recognition error due to high density of lead pitch is prevented. An IC garvity position coordinates and gradient thereof are calculated from the center coordinates of the four sides of an IC with an IC gravity-gradient calculating means 16, displacement to a robot head of an electronic part is calculated and it is then transmitted to a mounting device controller 10 for the high accuracy mounting.

Description

[Detailed description of the invention]

[Purpose of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a component mounting apparatus for automatically mounting electronic components and the like on a board at high speed and with high precision.

0002

2. Description of the Related Art In recent years, the density of mounting electronic components (hereinafter abbreviated as ICs) on printed circuit boards has become higher and higher. With regard to ICs as well, packaged components such as QFPs are being used more frequently than before as circuit integration increases.

As shown in FIG. 6, a component mounting apparatus (hereinafter referred to as
In order to mount the IC 2 having the leads L attracted and fixed to the robot head 1 of a mounting machine (abbreviated as a mounter) onto the printed circuit board 3, it is necessary to measure the amount of positional deviation of the IC 2 with respect to the robot head 1. Conventionally, IC recognition camera 4
After imaging the IC2, the image data is stored in the image memory in the visual recognition controller 5, and then all image data is binarized, and then the following arithmetic processing is performed to create the captured image. The centroid and slope of the binarized image were calculated.

Similarly, the recognition of the printed circuit board 3 is performed by capturing an image of the board mark 6 on the printed circuit board 3 with a board recognition camera 7, and then binarizing the image data via the visual recognition controller 5. are doing. After that, based on the image data from the visual recognition controller 5, the positional deviation between the IC 2 and the printed circuit board 3 is relatively corrected and aligned via the mounting machine controller 8, and the printed circuit board 3 is
Attach IC2 on top.

FIG. 7 is a diagram illustrating a model of the result of imaging an IC and performing binarization processing. When the optical system uses transmitted light, the image above the IC2 is dark and the rest is bright. Furthermore, in this figure, the measurement window W indicates the entire area that can be imaged by the IC recognition camera 4. Now, measure the four corner points of the window origin W0, end point W1, and W2.
, the same W3. The origin W0 of this measurement window W
Binarized image data is extracted in parallel to the X axis using the starting point. This is performed sequentially in the Y-axis direction. This is shown by the video data extraction lines L1 and L2 in FIG.

Since the video data extraction line L1 does not scan the binarized image, it is always in a dark state, that is, only has a value of 0, as shown in the scanning result R1 of FIG. On the other hand, in the case of the video data extraction line L2, since the lead L of the IC2 is scanned, the line has a sawtooth shape as shown in the scanning result R2. Conventionally, the coordinates of the center position of the IC2 have been detected by scanning the video data extraction line L2 on the lead L of the IC2 on all four sides of the IC2. Next, this method will be specifically explained using FIGS. 7 to 9.

It was previously explained that sawtooth data is obtained by the video data extraction line L2 shown in FIG. The center coordinates of IC2 in one side direction are calculated from this sawtooth waveform data. FIG. 8 is a model diagram explaining this.

First, let us say that the data obtained by the video data extraction line L2 is video data R2 in FIG. Now, when this data is subjected to binarization processing using a certain binarization threshold value, the result is as shown in FIG. From this result, it can be seen that the edges at both ends of each lead can be detected. The lead center is calculated from both ends. As a result, lead centers are detected for the number of leads.

Next, if one side of the IC 2, ie, the center of the lead group, is taken as the center of all the lead parts, this point can be calculated as the center of gravity of each lead center. FIG. 8 shows a model of the result of processing this work on all four sides of the IC.

In FIG. 8, a lead midpoint P1 is detected by drawing a video data extraction line L2 above the lead of IC2. Video data extraction line L on the left side of the lead
4, the lead midpoint P2 is detected. Similarly, by applying video data extraction lines L6 and L8 to the lower and right parts of the leads, the midpoints of the lead parts P3,
P4 is detected. Next, the middle point P1 of these leads
, P2, P3, P4 to calculate the IC measurement center of gravity G, which is the center of gravity position of IC2, and the IC inclinations θ1, θ2.

[0011] If a straight line connecting lead midpoints P1 and P3 is straight line A, and straight line B is connecting lead midpoints P2 and P4, the intersection of these two straight lines is the IC measurement point G. , the slope of these two straight lines in the X-axis and Y-axis directions is I
It is possible to obtain the C slope as θ1 and θ2. The calculation formula is as follows. The coordinates of the lead midpoints P1 to P4 are determined as follows. Lead midpoint P1: (xa, ya) Lead midpoint P2: (xb, yb) Lead midpoint P3:
(xc, yc) Lead part middle point P4: (xd, yd
) Equation of straight line A: (x-xa) x (yc-y
a) = (xc-xa) x (y-ya) Equation of straight line B: (x-xb) x (yd-yb
)=(xd-xb)×(y-yb) Coordinates of IC measurement center of gravity G: x=(mb-lb)/(la-
ma) y=(la×mb-lb×ma)/(la-ma) However, la, lb, ma, mb are la=(ya-yc)/(xa-xc) lb=(xa×
yc-xc×ya)/(xa-xc)ma=(yb-y
d)/(xb-xd)mb=(xb×yd-xd×yb
)/(xb-xd) Value of IC slope θ1: θ1
=tan-1[(yd-yb)/(xd-xb)] Value of IC slope θ2: θ2 =tan-1[(
yc-ya)/(xc-xa)] The final slope of the electronic component is IC slope θ1, θ2
The average value is sent to the mounting machine cotton roller 8.

[0012] By detecting the center of gravity position of the conventional board mark using the above-mentioned means and comparing that value with the amount of deviation from the camera center position, the amount of positional deviation and inclination of the robot head 1 and IC 2 are detected. Then, the actual mounting on the printed circuit board 3 was carried out while correcting the positional deviation.

[0013]

[Problems to be Solved by the Invention] In recent years, IC leads and lead pitches have tended to become denser and more diverse. Therefore, two problems have arisen as described below.

First, as the density of IC leads increases, it is becoming increasingly difficult to accurately recognize the leads. With the conventional optical system, the IC leads are crushed and it is no longer possible to properly image each IC. One way to solve this problem is to increase the camera resolution, but this is difficult because it requires changes to the optical system.

[0015] Furthermore, even if the camera magnification is simply increased, the viewing angle of the camera becomes smaller, making it impossible to capture a panoramic view of the IC. For this reason, the problem of accuracy in IC lead recognition is becoming more and more serious year by year. Although video data appears to be continuous data, it is actually discontinuous, and there is a limit to the resolution of the imaged object due to the density of the camera light receiving element and the optical magnification. When the IC lead pitch is extremely small, the video data actually becomes discontinuous data, so if lead detection is performed by binarization processing or the like, the lead pitch value will contain a large error.

In other words, when the IC leads themselves and their pitches are extremely small and only cover a few pixels of the camera light receiving element, conventional image processing techniques such as binarization or subtraction can cause extremely large variations in each lead and lead pitch. It means getting bigger.

A second problem is the diversification of IC shapes. In the conventional method, after capturing images of all ICs of various sizes with camera 1, the entire area of the captured screen is binarized, and then the IC lead position is determined for the binarized images of the ICs present in the window. Measure and calculate IC from the coordinate values.
After measuring the coordinates of the center of gravity, the positional deviation of the IC relative to the robot head was calculated. Therefore, the amount of calculation is large, so
Particularly in the case of electronic parts having large resin molded parts, there is a problem in that the processing time is large and the processing speed is reduced.

For example, in the conventional method described above, since the video data extraction line for detecting the center of each lead starts from the four corners of the measurement window, the lead part cannot be detected like the video data extraction line. This results in image scanning that is ultimately wasted.

[0019] This is particularly true when the external sizes of ICs mounted on a single printed circuit board are diverse, and the magnification and viewing angle of the IC recognition camera must be set to the maximum IC external size. In the conventional method, when an IC with a small external size is mounted, the proportion of the IC binarized image occupying the imaging screen, that is, the measurement window becomes small, and unnecessary calculation processing increases. Furthermore, when calculating the center of gravity of the IC, there is a possibility that noise may be introduced in areas other than the parts.
There was also the risk of erroneously measuring the center of gravity.

[0020]The present invention was made to solve the above-mentioned problems, and instead of processing the entire screen imaged by the imaging means, the IC lead required to calculate the position of the center of gravity. By predicting in advance the area where the IC exists and detecting the lead by scanning only that area, it is possible to prevent a decrease in the IC center of gravity detection speed, and to improve lead detection accuracy and electronic components by interpolating the video data. An object of the present invention is to provide a component mounting apparatus that can improve center of gravity measurement accuracy. [Structure of the invention]

[0021]

[Means for Solving the Problems] In order to achieve the above object, the present invention detects the positional deviation between the component and the board by visually recognizing the shape etc. of the component having leads, and detects the detected value. an imaging means for capturing an image of the component in a component mounting apparatus that relatively corrects the positions of the component and the board based on the above and mounts the component at a predetermined location on the board; and data regarding external dimensions of the component, etc. and an interpolation means for interpolating missing images of the component taken by the imaging means, and based on the data stored in the storage means, the leads of the component are displayed on the screen of the imaging means. Predicting and calculating the existing area, converting image data sent from the imaging means along the scanning line of the imaging means only for the area into grayscale image data, and binarizing the converted grayscale image data. The present invention provides a component mounting apparatus comprising lead detection means for detecting leads of the component, and calculation means for calculating the center of gravity coordinates and inclination of the component based on detection data from the lead detection means.

[0022]

[Operation] According to the component mounting apparatus of the present invention configured as described above, omissions in the image of the component taken by the imaging means are interpolated, and the image is taken based on data regarding external dimensions of the component stored in the storage means. Predicting and calculating the area where the component lead exists within the screen of the means, converting the image data taken in from the imaging means along the scanning line of the imaging means only for that area into grayscale image data, and converting the converted grayscale image data into grayscale image data. The image data is binarized, and the center of gravity coordinates and inclination of the component are calculated based on the lead detection data of the component.

[0023] As a result, after the part is imaged, part lead detection processing is not performed for parts that are not necessary for measuring the center of gravity of the part, and interpolation processing is performed for the video data on the leads, thereby speeding up the recognition processing.・High precision can be achieved.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the component mounting apparatus of this embodiment includes an IC data receiving means 11 that receives the IC external size from the mounting machine controller 10, and an IC data receiving means 11 that receives the IC external size from the mounting machine controller 10.
A recognition area calculating means 12 for predicting the C imaging area, an IC imaging means 13 for actually imaging the IC, an image memory 14 for storing image data from the IC imaging means 13, and an IC lead for the captured image on the screen. IC lead detection means 15 detects IC leads by data interpolation processing; IC gravity center/inclination calculation means 16 calculates the center of gravity/inclination of the IC itself from the center of each detected IC lead; The main control section is composed of an IC correction data transmitting means 17 that calculates correction data for mounting and transmits it to the mounting machine controller 10.

In this embodiment having the main control section configured as described above, the IC imaging means 13 images the IC sucked to the robot head within the mounting machine. This captured image means that it is stored in the image memory 14 as sawtooth data R2 as shown in FIG. Thereafter, through communication with the mounting machine controller 10, the imaged external size data of the IC 2 shown in FIG. 2 is taken into the main control section.

Next, based on this data, the recognition area calculation means 12 calculates a region of the IC image data, that is, a region of the image data stored in the image memory where the IC 2 and its IC lead L are predicted to exist. Calculate. In this embodiment, the IC lead detecting means 1 only applies to this area.
5, the image data stored in the image memory 14 is subjected to interpolation processing, thereby calculating the center coordinates of the IC 2 in four directions while preventing recognition errors caused by increased lead pitch density. Thereby, the IC lead L can be detected efficiently and with high precision.

Next, from the center coordinates of the four sides of the IC, the IC center of gravity/inclination calculation means 16 calculates the coordinates of the center of gravity of the IC2 and its inclination, and based on this, calculates the amount of positional deviation of the electronic component relative to the robot head. The information is then transmitted to the mounting machine controller 10, and the IC 2 is mounted on the printed circuit board with high precision. In order to mount the IC2 in the printed circuit board mounting machine, visual recognition positioning processing is performed using a camera serving as an IC imaging means. The processing will be explained below with reference to FIG.

First, the external shape data of the IC 2 to be recognized is received from the mounting machine controller 10 as a recognition condition (4-1). As shown in FIG. 2, the received data includes IC external dimensions IC1 to IC4, which are external sizes of IC2 having leads L, lead pitch P1,
P2, the number of lead pins, lead bending tolerance, pixel calibration value, number of IC leads, etc. are the contents.

Next, the IC is imaged with a camera. The captured image data is transmitted to the main control section, and the A/D is processed within the control section.
Immediately after the conversion process, the image is stored in the image memory. After this, based on the pixel calibration values received in the same way as the values of the IC outline IC1 to IC4 and the lead pitches P1 and P2,
A small measurement window Wi shown in (4-2) is calculated. As a specific calculation example, the following formula is given. [Measurement window origin (XF, YF)] XF=25
5-(X1×r×a) YF=240-(Y1×r×a) [Measurement window end point 1 (XF, YF)] XF=255
−(X1×r×a) YF=240−(Y1×r×a) However, regarding a/r, a: Calibration data (pixel calibration value) r: Window safety factor (1.0 to 2 .0) This indicates the ratio of window size to IC size. X1: IC external form IC1 Y1: IC external form IC
3. In this equation, the camera coordinate system is 512×480. That is, the coordinates (255, 240) indicate the camera center coordinates.

Next, the video data extraction line Li1 is sequentially moved and scanned from the top of this small measurement window Wi in the positive direction of the Y-axis. As this scanning continues, the area where the lead L on the top of the IC is present is eventually reached (=video data extraction line Li2) (4-3). At this location, IC lead detection is started (4-3). next,
The video data interpolation process for IC lead detection will be described.

[0032] The video data to be interpolated is limited to only the area of the video data near the top of the IC lead where the video level difference is large. That is, this means that data interpolation is performed for each IC lead. As an interpolation formula, the following formula can be considered. Real values: X0, X1, X2, X3...Xn and function values: f(X0), f(X1), f(X2), f
When (X3),...f(Xn) are given, the nth degree polynomial passing through this (n+1) point is

Now, assume that the X-axis is the video data coordinate and the Y-axis is the video level (=shading level). Based on the interpolation formula calculated in this way, the video data is numerically analyzed in units of 1/10 pixel. The data derived thereby can be applied as data on IC leads and other areas that could not be captured due to the limited resolution of the camera light receiving element.

[0034] Therefore, this data is subjected to binarization processing,
Alternatively, by performing differential processing, it becomes possible to detect the left and right edges of the IC lead in units of 1/10 pixel, that is, in units of subpixels. Figure 5 models this.

For example, in FIG. 5, pay attention to the IC lead in the middle. Since the video data is not interpolated in the conventional method, the width of this IC lead is determined by the value of the video data itself shown in FIG. 5(b), that is, the IC lead edge LE'
, the same RE', and the width is 3 pixels. However, in this embodiment, since the video data is interpolated, FIG.
LE' and RE' shown in b) are the IC lead edges LE and RE shown in FIG. 5A, and the width of the IC lead is detected more accurately.

Therefore, the lead widths H1 and H2 in FIG. 5(a)
, H3 detect the lead width more accurately than H1', H2', and H3' in FIG. 5(b). thus,
It becomes possible to detect the IC lead width with higher precision than before.

Furthermore, the center of the IC lead is determined by finding the midpoint between the left and right edges of each IC lead, but the distance between these centers, that is, the lead pitch LP1 shown in FIG. 5(a)
, LP2 are also the lead pitches LP1′,L in FIG. 5(b).
This results in more accurate detection compared to P2'. Through this process, the midpoint Pi1 of the IC lead part in FIG. 4 is calculated (
4-3). After this, a check is performed by comparing the detected number of IC leads and lead pitch with the received IC external shape data shown in FIG. 2 (4-4).

After this, the leads on the left, bottom, and right parts of the IC are detected in order (4-6, 4-8, 4-10). However, at this time, on the three sides of the IC, the areas where IC leads are present, that is, areas A to D, are also predicted in advance. That is, these are the coordinates of each of the four corners of area B, area C, and area D in FIG. The calculation procedure is performed using the following formula, for example. [B area] B area 1 point B1 X=255-(X1
×r×a/2)
Y=240-(Y1×r×a/2) B
Area 2 points B2 X=255-(X2×(2-r
)×a/2)
Y=240-(Y1×r×a/2) B area 3 points B3 X=255-(X2×(2-r)
×a/2)
Y=240+(Y1×r×a/2) B area 4 points B4 X=255−(X1×r×a/2)
Y=2
40+(Y1×r×a/2) [C area] C area 1 point C1 X=255−(X1
×r×a/2)
Y=240+(Y1×r×a/2) C
Area 2 points C2 X=255-(X2×(2-r
)×a/2)
Y=240+(Y1×r×a/2) C area 3 points C3 X=255−(X2×(2−r)
×a/2)
Y=240+(Y1×r×a/2) C area 4 points C4 X=255−(X1×r×a/2)
Y=2
40+(Y1×r×a/2) [D area] D area 1 point D1 X=255−(X1
×r×a/2)
Y=240-(Y1×r×a/2) D
Area 2 points D2 X=255-(X2×(2-r
)×a/2)
Y=240-(Y1×r×a/2) D area 3 points D3 X=255-(X2×(2-r)
×a/2)
Y=240+(Y1×r×a/2) D area 4 points D4 X=255−(X1×r×a/2)
Y=2
40+(Y1×r×a/2) However, a/r is as follows: a: Calibration data (pixel calibration value) r: Window safety factor (1.0 to 2.0) This is the window for the IC size It shows the ratio of the size of . X1: IC outline IC1 X2: IC outline IC2 Y1: IC outline IC3 Y2: IC outline IC4

In this way, lead detection on each side of the IC is performed while calculating areas B to D for lead detection. Conventionally, scanning was performed to extract video data from the top of the camera coordinate system in order to search for an IC lead, but now it is sufficient to start from the top of the child measurement window Wi. When the leads on the top of the IC are searched, the number of lead pins and lead pitch are checked. If both are within the allowable range, the coordinates of each lead center position are determined, and the center of the entire IC upper lead group, that is, the center point Pi1 of the lead portion in FIG. 4 is calculated from the obtained value.

Next, based on this lead part midpoint Pi1, FIG.
Three areas B, C, and D shown in are calculated. Now, as shown in Figure 4, the four points that make up this area are each B area B1.
~B4, C areas C1 to C4, and D areas D1 to D4. Since the lead midpoints Pi2 to Pi4 exist within the above area, the lead search by scanning the video data is performed only in areas B to D.

That is, starting from a line segment connecting one point B1 and two points B2 in area B, scanning is performed in parallel toward the center of the electronic component. Regarding C area, C area 1 point C1 and 2 points C2
A lead search is also performed for the line segment connecting the D area, starting from the D area 1 point D1 and the 2 point D2. The above operations are carried out by the IC lead detection means 14 shown in FIG. The processes detailed above correspond to 4-3 to 4-10 in FIG.

Next, the center of gravity (I
C measurement center of gravity G) and slope (average value of IC slopes θi1 and θi2) are calculated (4-12). The calculation method can be the same as in the conventional example.

After measuring the IC center of gravity and inclination, the distance from the center coordinates of the camera is calculated and transmitted to the mounting machine controller 10 (4-13). Further, if an abnormality is detected when detecting each side of the IC lead, an abnormality code is transmitted to the mounting machine controller 10 (4-14).

As described in detail above, in this embodiment, IC leads can be detected in subpixel units, and problems such as poor lead recognition and errors when detecting IC leads caused by the limits of camera resolution can be prevented. It becomes possible.

Furthermore, in order to visually recognize only the area where the lead image is required when detecting the position of the IC, the IC
Alternatively, even if noise occurs around the IC, the position of the IC can be detected while avoiding it, and the accuracy of position detection is improved. Further, since image processing for recognition is not performed on unnecessary portions of the IC, the position detection efficiency is improved and it is also possible to speed up the IC recognition process.

Further, in the above embodiment, only the method for detecting the position of an IC has been described, but the present invention is also applicable to the recognition of printed circuit board marks, such as detecting the position of a printed circuit board.

That is, board marks include round, square, triangular, and cross shapes. These are imaged with an ITV camera, and then binarized and measured to detect their center of gravity. At the time of measurement, if the shape of the board mark is filed in the visual recognition device in advance, the data can be used to identify the board mark. It becomes possible to predict the area where the edge detection point exists, and it becomes possible to set an efficient measurement window in advance, thereby improving the recognition processing speed. Furthermore, in this case, since the recognition processing measurement is not performed on unnecessary portions, it is possible to avoid the influence of noise on and in the vicinity of the board mark, and it is also possible to improve the position detection accuracy.

Furthermore, if the video data interpolation process described above is applied to board mark recognition, it becomes possible to recognize the outer edge of the mark with higher accuracy, thereby improving the accuracy of measuring the center of gravity of the board mark.

[0049]

[Effects of the Invention] As described above, according to the present invention, I
Deterioration in recognition accuracy is prevented by interpolating video data and recognizing it in sub-pixel units to prevent lead recognition failures caused by increased C-lead density and camera resolution limitations.

Furthermore, since recognition processing is performed on unnecessary points when measuring the position of an electronic component, it is possible to prevent the problem that recognition accuracy is degraded due to the influence of noise and the problem that processing time is required.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing main control parts of an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing IC external shape data applied in an embodiment of the present invention.

FIG. 3 is a control flowchart applied in one embodiment of the present invention.

FIG. 4 is a model diagram showing data applied in an embodiment of the present invention.

FIG. 5 is a diagram illustrating data interpolation applied in an embodiment of the present invention.

FIG. 6 is a schematic configuration diagram showing the hardware configuration of an embodiment of the present invention.

FIG. 7 is a model diagram showing the result of imaging and binarizing an electronic component.

8 is a diagram illustrating calculation of center coordinates of an electronic component from the binarization processing result shown in FIG. 7. FIG.

[Explanation of symbols]

Claims (1)

[Claims] 1. A positional deviation between the component and the board is detected by visually recognizing the shape etc. of the component having the lead, and the positions of the component and the board are relatively corrected based on this detected value, A component mounting apparatus for mounting the component on a predetermined location on the board, comprising an imaging means for capturing an image of the component, a storage means for storing data regarding external dimensions of the component, and a lack of the captured image of the component. and an interpolation means for interpolating a lead of the component in the screen of the imaging means based on the data stored in the storage means, and predicts and calculates the area where the lead of the component exists within the screen of the imaging means, and calculates the area where the lead of the component exists only for the area a lead detection means for converting image data sent from the imaging means into grayscale image data along a scanning line, binarizing the converted grayscale image data, and detecting a lead of the component; A component mounting apparatus comprising: arithmetic means for calculating the center of gravity coordinates and inclination of the component based on detection data from the detection means.