JPH02123476A - Pattern reader - Google Patents

Abstract

PURPOSE:To easily change the resolution of pattern reading by changing sampling frequency for the digitalization of an image signal in accordance with the resolution. CONSTITUTION:A CCD line sensor 3 reads out a wiring pattern 2 every movement of a printed-wiring substrate 1 by a fixed distance in an arrow direction. A line sensor driver 4 drives the sensor 3 so as to read out image data within charge accumulation time corresponding to a shift pulse with a fixed frequency. The driver 4 transfers the read pattern data to a binarizing circuit 5. The circuit 5 binarizes the image signal of the sensor 3 applied through the driver 4 in accordance with a sampling pulse applied from a frequency modulating circuit 8. The circuit 8 applies the sampling pulse with the frequency corresponding to the pattern reading resolution previously set up in a control part 11 to the circuit 5.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a pattern reading device, and is used, for example, in a pattern inspection device for inspecting defects in wiring patterns of printed circuit boards.

<Prior Art> A method of inspecting the wiring pattern of a printed circuit board is to read the wiring pattern with an image sensor and compare the read wiring pattern with a standard pattern to detect defects.

Conventionally, in this method, the resolution of pattern reading has generally been fixed. In addition, when changing the resolution, the required resolution for the line width of the wiring pattern to be inspected can be achieved by adjusting or replacing the optical system (for example, a lens, etc.) before reading the pattern with the image sensor. I was trying to get it.

These methods were applied to printed circuit boards in which the minimum line width of the wiring pattern was about 200 microns and the substrate material was hard, such as glass epoxy.

<Problems to be Solved by the Invention> Recently, flexible wiring boards made of soft materials such as polyimide and polyester have been used as wiring boards that enable high-density packaging.

The line width of the wiring in this flexible wiring board varies greatly depending on its use, and ranges from, for example, a line width of about 51 m to a thin one of about 50 microns.

In the conventional method of inspecting the wiring pattern of an I8 board by reading it with a fixed resolution (flexible wiring with various line widths like this), it is difficult to reduce the inspection speed when the line width is large. There are problems in that it is unnecessarily slow and the inspection accuracy decreases when the line width is small.

On the other hand 1. In the method of changing the resolution by adjusting or replacing the optical system, there is a problem that the adjustment or replacement requires skill and takes a long time. Furthermore, since it was done manually, there was also a problem in reading accuracy.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a pattern reading device whose resolution can be easily changed.

<Means for Solving the Problems> In order to achieve the purpose described above, in the pattern reading device according to the present invention, the sampling frequency when digitizing the azucog output of the image reading element is adjusted to the pattern reading resolution. The apparatus includes a sampling frequency changing means for changing the sampling frequency according to the changed sampling frequency, and a pattern data creating means for creating pattern data by digitizing the analog output according to the changed sampling frequency.

<Operation> The pattern reading device according to the present invention changes the amount of pattern data by changing the sampling frequency when digitizing the analog output of the image reading element according to the pattern reading resolution setting. Read with the corresponding resolution.

<Embodiment> FIG. 1 shows the configuration of a printed circuit board inspection device to which a pattern reading device of this embodiment is applied.

In the figure, 1 is a printed wiring board, 2 is a wiring pattern, 3 is a CCD line sensor, 4 is a line sensor driver, 5 is a binarization circuit, 6 is a memory, 7 is a defect detection circuit, 8
1 is a frequency modulation circuit, 9 is a table wiper, 10 is a standard data storage memory, and 11 is a control section.

A printed wiring board 1 has a wiring pattern 2 to be inspected.
is formed. The wiring pattern 2 has a shape as shown in FIG. 2, for example. This printed wiring board 1 is
It is fixed to a table (not shown) movable in the direction of the arrow.

The CCD line sensor 3 reads the wiring pattern 2 every time the printed wiring board 1 moves a fixed distance in the direction of the arrow. The line sensor driver 4 drives the line sensor 3 to read image data in a charge accumulation time corresponding to a constant frequency shift pulse. The line sensor driver 4 further converts the read pattern data into a binarization circuit 5.
Transfer to.

The binarization circuit 5 operates the line sensor driver 4 according to the sampling pulse given from the frequency modulation circuit 8.
The image signal from the CCD line sensor 3 provided via the CCD line sensor 3 is binarized. The image memo 6 stores binarized pattern data.

The defect detection circuit 7 compares the pattern data to be inspected stored in the image memory 6 with the standard pattern data stored in the standard data memory 10, and detects defects in the pattern to be inspected 2.

The frequency modulation circuit 8 provides the binarization circuit 5 with a sampling pulse having a frequency corresponding to the pattern reading resolution set in the control section 11 in advance.

The table driver 9 drives the table on which the printed wiring board 1 is placed in the direction of the arrow by a distance corresponding to the reading width of one line each time the CCD line sensor 3 completes reading one line of the wiring pattern 2. do. (Note that the table may move by the length of the decomposed fat while the CCD line sensor is reading.) The standard data memory 10 stores wiring pattern data that serves as a reference for comparison. The control unit 11 executes control of the entire system including control of the sampling frequency corresponding to the resolution of pattern reading.

The pattern reading processing procedure will be described below.

FIG. 3 (al shows the analog output of the CCD line sensor 3 that read the pattern, area A is the pattern part and area B is the non-pattern part. (b) is the sampling pulse, (C) is the binary pattern data, (dl is the data obtained by converting the pattern data into binary numbers of “1” and “O”. The image memory 6 contains this (dl)
data is written.

Assuming that the frequency of the sampling pulse given to the binarization circuit 5 is f, the binarization circuit 5 samples the analog output of the CCD line sensor 3 at a period of 1/f, as shown in FIG.
Convert to the pattern data shown in C). In this case, the pattern data output from the binarization circuit 5 (FIG. 3(d))
) is equal to 1/f. Therefore, the resolution is 1/f.

FIG. 4 shows an example in which the sampling frequency is set to 1/2 of that in FIG. 3. Fig. 4 (al is the analog output of the CCD line sensor 3, which is the same as Fig. 3 (a). Fig. 4 (b) is the sampling pulse,
The binarization circuit 5 samples and binarizes the analog output (a) using this sampling pulse with a period of 2/f. Figure 4 (C) is the binarized pattern data, and Figure 4 (fd) shows the pattern data in (C) as "1".
, is data converted into a binary number of "0".

In this case, the binarization circuit 5 samples the analog output of the CCD line sensor 3 at a period of 2/f, and
1.Convert to pattern data of (d).

The width or resolution of each bit of the pattern data in (d) is equal to 2/f. Therefore, by reducing the sampling frequency to 1/2, the resolution becomes 1/2.

Note that in the above embodiment, a case was explained in which a pattern is read on a printed wiring board with a resolution of -.
It is also possible to read the printed wiring board by changing the resolution for each part.

Further, it is also possible to use a roll-to-roll method T: supplying a printed wiring board to be read as shown in FIG.

<Effects of the Invention> As explained above, in the present invention, the resolution of pattern reading is changed by changing the sampling frequency in digitizing the image signal, so the resolution can be easily changed. In pattern inspection, inspection speed can be optimized according to the pattern, and inspection accuracy can be improved. Further, there is no need for complicated work that requires skill, such as adjusting or replacing the optical system, and it is possible to automate the reading of many types of flexible wiring boards.

[Brief explanation of the drawing]

1 and 5 are block diagrams showing the configuration of the embodiment of the present invention, FIG. 2 is a diagram showing the wiring pattern of the embodiment of the present invention, and FIGS. 3 and 4 are diagrams showing the pattern data of the embodiment of the present invention. It is a figure which shows a waveform. 1... Printed wiring board 2... Wiring pattern, CCD line sensor, line sensor driver, binarization circuit, image memory, defect detection circuit, frequency modulation circuit, table driver, standard data memory, control section

Claims (1)

[Claims] In a pattern reading device that reads a pattern with an image reading element and digitizes the analog output of the image reading element to create pattern data, a sampling frequency changing means changes the sampling frequency of the analog output according to a setting of pattern reading resolution. and pattern data creation means for creating pattern data by digitizing the analog output according to the sampling frequency.