JPH05256620A - Circuit board inspecting device - Google Patents

Abstract

PURPOSE:To provide a circuit board inspecting device capable of correctly determining the center of gravity position of a fitted part item and precisely judging the position drift. CONSTITUTION:A circuit board inspecting device is provided with an image pickup unit 2 photographing an electronic part item C fitted on a circuit board K, an edge position calculating means 3b calculating the edge position based on the intensity data of multiple edge detection lines crossing the electronic part item C, a center of gravity position calculating means 3d calculating the center of gravity position of the fitted part item C based on the edge position, a judging means 3f comparing the obtained center of gravity position with the reference position and judging the position drift of the fitted part item C, and the second edge position calculating means 3c calculating the edge position based on 1/2 of the sum of the coordinates of the intersection of the upper limit and the lower limit of the threshold value specified by the intensity data and the maximum value and minimum value of the intensity data when the detection point of the intensity data does not exist between the upper limit and lower limit of the threshold value of the intensity data obtained by the edge detection line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board inspection device for inspecting the mounting state of electronic components mounted on a circuit board.

[0002]

2. Description of the Related Art A circuit board inspection apparatus of this type comprises a two-dimensional camera for picking up an image of an electronic component (hereinafter, simply referred to as a component) mounted on a circuit board, and an image processing apparatus using a microcomputer. It is configured. In the image processing device, the edge position is calculated from the luminance data of a plurality of edge detection lines intersecting with the component obtained through the camera, the position of the center of gravity of the mounted component is calculated from the edge position, and the position is compared with the reference position. Judgment such as deviation is performed.

A conventional determination method implemented by the above image processing apparatus will be described in detail below by taking a prism-shaped component C having electrodes Ca at both ends as an example.

First, as shown in FIG. 3, each of the four edge detection lines X intersects with the electrodes Ca at both ends in the X and Y directions, respectively.
The continuous luminance data as shown in FIG. 4 is extracted from 1 to X4 and Y1 to Y4 respectively, and the edges x1 to x4 which are the boundary positions between the electrode Ca and the solder print portion Ka are extracted from the respective luminance data.
And the coordinates of y1 to y4 are obtained. The eight edge detection lines are set in advance according to the position where the electrode Ca should originally come.

Next, the X coordinate CX and the Y coordinate CY of the center of gravity CG of the part C are calculated from the average of the X coordinates of the edges x1 to x4 in the X direction and the average of the Y coordinates of the edges y1 to y4 in the Y direction. .. Thus, the coordinates (CX, CY) of the center of gravity CG of the component C mounted on the circuit board K are obtained.

The method for calculating the coordinates of the edges x1 to x4 and y1 to y4 is to calculate the maximum value MA of the luminance data shown in FIG.
Specified by X and minimum value MIN, for example 80% of maximum value MAX
And the upper limit of the threshold specified by 20% and the lower limit L
It depends on whether or not a luminance data detection point is entered during OW.

That is, as shown in FIG. 5, among the detection points P1 to P5 of the brightness data, three detection points P are detected.
2, P3 and P4 are the upper limit HIGH and the lower limit LOW of the threshold
If it falls within the interval, the X coordinate X0 of the edge is obtained from the following equation.

X0 = Σ (Xi · Fi) / Σ (Fi) Xi: X coordinate of the detection point Fi: Luminance level value On the other hand, as shown in FIG. 6, the luminance data detection point P1
All of P5 to P5 are the upper limit HIGH and the lower limit LOW of the threshold value.
In the case where the brightness does not fall within the range, for example, when the side surface of the electrode Ca is shaded due to the illumination of the component C and the obtained brightness data has a steep gradient, the above equation cannot be used. Upper limit of data and threshold value and lower limit LO
From the X-coordinates of the intersections A and B with W and the brightness level value, the X-coordinate X0 of the edge is obtained by the following equation.

X0 = {(XA.FA) + (XB.FB
)} / (FA + FB) XA: X coordinate of intersection A XB: X coordinate of intersection B FA: Luminance level value of intersection A FB: Luminance level value of intersection B The above also applies to edge detection lines Y1 to Y4 in the Y direction Similarly to the above, the Y coordinates of the edges y1 to y4 are appropriately obtained.

Then, the coordinates (CX,
CY) is compared with preset reference coordinates, and if the center of gravity CG of the component C has a deviation exceeding the allowable range, the position deviation is determined.

[0011]

However, in the latter edge position calculation method described above, the lower limit LOW of the threshold value cannot be set too low due to noise elimination, and this influences the X coordinate of the obtained edge. As shown in FIG. 6, X0 becomes very close to the upper limit HIGH of the threshold value.

For example, the X coordinate XA of the intersection A is 2.1, the X coordinate XB of the intersection B is 2.8, and the brightness level value FA of the intersection A is
8 and the brightness level value FB of the intersection B is 2, the value of the X coordinate X0 of the edge becomes 2.24, and the obtained X coordinate X0 of the edge is close to the X coordinate XA of the intersection A.

That is, in the latter edge position calculation method, it is not possible to obtain proper edge coordinates, that is, edge coordinates that are desired to be substantially the midpoint between the upper limit HIGH and the lower limit LOW of the threshold value. There is a problem that the coordinates of the center of gravity CG of the component C obtained from the above become inaccurate, and it becomes impossible to accurately determine the position shift or the like.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a circuit board inspection apparatus capable of accurately determining the position of the center of gravity of a mounted component and determining the positional deviation and the like with high accuracy. To do.

[0015]

In order to achieve the above object, according to the present invention, an image pickup device for picking up an image of an electronic component mounted on a circuit board, and luminance data of a plurality of edge detection lines intersecting with the electronic component. Edge position calculating means for calculating the edge position from the edge position, center of gravity position calculating means for calculating the center of gravity position of the mounting component from the edge position, and comparing the determined center of gravity position with a reference position to determine the displacement of the mounting component, etc. In the circuit board inspecting device equipped with the judging means, when the detection point of the luminance data does not fall between the upper limit and the lower limit of the threshold in the luminance data obtained on the edge detection line,
2 of the sum of the coordinates of the intersection of the brightness data and the upper and lower limits of the threshold value defined by the maximum value and the minimum value of the brightness data
A second edge position calculation means for calculating the edge position from 1 / min is provided.

[0016]

In the inspection apparatus according to the present invention, when the luminance data detection point does not fall between the upper and lower thresholds of the luminance data obtained on the edge detection line, the second The edge position calculation means calculates the edge position from one half of the sum of the coordinates of the intersection of the brightness data and the upper and lower limits of the threshold value defined by the maximum value and the minimum value of the brightness data. From the edge position, the center-of-gravity position calculating means obtains the center-of-gravity position of the mounted component. The determined position of the center of gravity of the mounted component is compared with the reference position in the determination means,
As a result, the displacement of the mounted component and the like are determined.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 schematically shows a circuit board inspection apparatus to which the present invention is applied. In the figure, 1 is a transport table made up of an XY-θ table or the like, 2 is a two-dimensional camera with an illuminator 2a using a CCD or the like, and 3 is an image processing apparatus using a microcomputer. 4 is a monitor, K is a circuit board, and C is a component mounted on the circuit board K.

The image processing device 3 includes an image memory 3a for storing brightness data required for edge position calculation through the camera 2.
The first and second edge position calculation circuits 3b and 3c for calculating the edge position from the brightness data, the center of gravity position calculation circuit 3d for calculating the center of gravity position from the edge position, and the judgment reference data. It is provided with a reference position memory 3e for storing and a determination circuit 3f for comparing the obtained center of gravity position with the reference position to determine the displacement of the mounted component and the like.

The determination method carried out by the image processing apparatus 3 will be described below with reference to a prismatic part C having electrodes Ca at both ends.
Will be described as an example. In this description, FIGS. 3 to 5 described above are cited.

First, the mounting part C is imaged by the camera 2,
As shown in FIG. 3, four edge detection lines X1 to X4 and Y1 which intersect the electrodes Ca at both ends in the X and Y directions, respectively.
The continuous luminance data as shown in FIG. 4 are extracted from Y4 to Y4 and stored in the image memory 3a. MAX and MIN in FIG. 4 are the maximum and minimum values of luminance data, and HIGH and LOW are, for example, 80% of the maximum value MAX.
And the upper limit of the threshold specified by 20% and the lower limit L
OW.

When the luminance data detection points fall between the upper limit HIGH and the lower limit LOW of the threshold value, that is, as shown in FIG. 5, three detection points among the luminance data detection points P1 to P5 are detected. When P2, P3 and P4 fall between the upper limit HIGH and the lower limit LOW of the threshold value, the X coordinate X0 of the edge is obtained by the following equation in the first edge position calculation circuit 3b.

X0 = .SIGMA. (Xi.Fi) /. SIGMA. (Fi) Xi: X coordinate of the detection point Fi: Brightness level value In the case of the edge detection lines Y1 to Y4 in the Y direction, the same applies to the case of the edges y1 to y4. The Y coordinate is obtained as appropriate.

Further, the upper limit HIGH and the lower limit LO of the threshold value are set.
When the luminance data detection point does not fall within W, that is, as shown in FIG. 2, all the luminance data detection points P1 to P5 do not fall between the upper limit HIGH and the lower limit LOW of the threshold value. In this case, the luminance data and the upper limit H of the threshold value
From the X-coordinates of the intersections A'and B'of IGH and the lower limit LOW, the X-coordinate X0 'of the edge is calculated by the following equation in the second edge position calculation circuit 3c.

X0 '= (XA' + XB ') / 2 XA': X coordinate of intersection A'XB ': X coordinate of intersection B'That is, X coordinate XA' of intersection A'is 2.1 and intersection B ' ´
When the X coordinate XB 'of the edge is 2.8, the value of the X coordinate X0 of the edge becomes 2.45 from the above equation, and the X coordinate X0' of the obtained edge is the upper limit HIGH and the lower limit LOW of the threshold value.
The coordinate X0 'does not come close to the upper limit HIGH of the threshold value as in the conventional case. Also in the case of the edge detection lines Y1 to Y4 in the Y direction, the Y coordinates of the edges y1 to y4 are appropriately obtained in the same manner as above.

Next, in the center-of-gravity position calculation circuit 3d, the center of gravity CG of the part C is calculated from the average of the X coordinates of the edges x1 to x4 in the X direction and the average of the Y coordinates of the edges y1 to y4 in the Y direction.
The X coordinate CX and the Y coordinate CY of are calculated. With the above, the coordinates of the center of gravity CG of the component C mounted on the circuit board K (CX, CY
) Is required.

Next, the determination circuit 3f compares the obtained coordinates (CX, CY) of the center of gravity CG of the component C with a preset reference coordinate, and the center of gravity CG of the component C has a deviation exceeding the allowable range. In this case, the position shift is judged. The circuit board K that has received the positional deviation determination is removed from the line in a later step.

As described above, in the above-described inspection apparatus, even if the detection point of the luminance data does not fall between the upper limit HIGH and the lower limit LOW of the threshold in the luminance data obtained on the edge detection line, the luminance is not detected. Upper limit of data and threshold H
The coordinates of the center of gravity CG of the mounting component C can be accurately obtained by properly capturing the edge coordinates from the coordinates of the intersections A'and B'with the IGH and the lower limit LOW. In other words, even when the former coordinate calculation formula cannot be used due to the influence of illumination or the like on the mounted component C, it is possible to accurately determine the coordinates of the center of gravity CG of the mounted component C and perform the displacement determination with high accuracy. Become.

[0028]

As described in detail above, according to the present invention,
Even if the detection point of the luminance data does not fall between the upper limit and the lower limit of the threshold in the luminance data obtained on the edge detection line, the intersection of the luminance data and the upper and lower limits of the threshold. Therefore, the edge position can be properly captured and the position of the center of gravity of the mounted component can be accurately obtained, which enables highly accurate determination of the positional deviation and the like.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a circuit board inspection apparatus to which the present invention is applied.

FIG. 2 is a diagram showing luminance data on an edge detection line.

FIG. 3 is a top view and a side view of a component showing a procedure for calculating a center of gravity.

FIG. 4 is a diagram showing luminance data on an edge detection line.

FIG. 5 is a diagram showing luminance data in an edge detection line.

FIG. 6 is a diagram showing luminance data on an edge detection line.

[Explanation of symbols]

K ... Circuit board, C ... Component, CG ... Center of gravity, 2 ... Camera, 3
... image processing device, 3b ... first edge position calculation circuit, 3
c ... Second edge position calculation circuit, 3d ... Centroid position calculation circuit, 3f ... Judgment circuit, X1 to X4, Y1 to Y4 ... Edge detection line, x1 to x4, y1 to y4 ... Edge, MAX
... maximum value of brightness level, MIN ... minimum value of brightness level,
HIGH ... upper limit of threshold, LOW ... lower limit of threshold,
A ', B' ... intersection, X0 '... edge X coordinate.

Claims (1)

[Claims] 1. An image pickup device for picking up an image of an electronic component mounted on a circuit board, an edge position calculating means for calculating an edge position from brightness data of a plurality of edge detection lines intersecting with the electronic component, and the edge. Edge detection in a circuit board inspection device equipped with a center-of-gravity position calculation means for determining the center-of-gravity position of the mounted component from the position, and a determination means for comparing the calculated center-of-gravity position with a reference position to determine the displacement of the mounted component, etc. When the detection point of the luminance data does not fall between the upper limit and the lower limit of the threshold in the luminance data obtained on the line, the luminance data and the maximum and minimum values of the luminance data The mounting component inspection device further comprises a second edge position calculating means for calculating an edge position from a half of a sum of coordinates of intersections with upper and lower limits of the threshold defined by