JPS5950307A - Laser type surface inspecting device - Google Patents

Abstract

PURPOSE:To always set a gate signal in a necessary inspecting area of an analog waveform, and no cause to malfunction, by setting a phase and width of the gate signal in an automatic following form in conformity with a variation of an analog signal. CONSTITUTION:An analog signal from an inspecting head becomes a square wave by a comparator 21, and the width W of the square wave is measured by counting a clock of a clock oscillator 3 by a counter 22. The measured value is latched by a latching circuit 23. On the other hand, a counter 24 counts a set value alpha of a presetting circuit 26 by a clock from rise of an output square wave of the comparator 21, generates an output after completing the counting, and sets a flip-flop 29. A counter 26 counts a clock from rise of the output square wave of the comparator 21 by setting a preset value beta of a presetting circuit 27 as an initial value, but a comparator 28 compares a latched data of the latching circuit 23, namely, analog signal width WN-1 before one scanning with a count value of the counter 26, generates an output signal in case of coincidence, resets the flip-flop 29, and simultaneously, resets the counter 26, too.

Description

[Detailed Description of the Invention] According to this invention 1, when inspecting surface defects of metal plates, etc.,
This invention relates to a surface inspection device using a laser that prevents malfunctions due to meandering of circular metal plates or variations in plate width.

Conventionally, there has been a defect detection processing section for this type of device as shown in FIG. In the figure, (1a) is the scanner drive circuit, (2) is the clock Shinshu oscillator, and (3) is the number set by the preset circuit (4) from the rise of the reference signal pulse output from the scanner drive circuit (1a). (5) is a counter that counts the number of clocks of the clock signal oscillator (2), (5) is a counter that counts and records the number of clocks set by the preset circuit (6) after the counter (4) has finished counting, and (7) is a counter that counts the number of clocks set by the preset circuit (6) after the counter (4) has finished counting. A flip-flop operates using the output of the counter (3) and the output of the counter (5), (8) is the inspection head corresponding to the sensor section, and (9) is the inspection head (8).
Q() is a comparator that extracts a defect signal from the analog signal output from the flip-flop (7) and a comparator (9).
) is an AND circuit that takes the AND of the outputs of '111
1f'1EK). 1.3°76°, 2. -66.5 In (8), an optical scanner is used to scan a laser beam onto the scanned plate, but the drive circuit of this scanner is Q.
A reference signal is output from 0, and the inspection head (8)
It has a certain phase difference with the analog signal output from.

From the rise of the reference signal from the clock oscillator (
The output of step 2) is counted, and the end position of the test within the width of the analog signal output from the test head (9) is determined based on the count completion position. After the counter (3) has finished counting, the counter (5) counts the output of the clock oscillator (2) by the number set by the preset device (6),
Determine the inspection end position within the analog signal width. counter(
A flip-flop (7) is operated using the output of 3) and the output of the counter (5) to generate a rectangular wave. On the other hand, inspection head (8)
The analog signal outputs from are compared by a comparator (9) and defective signals are extracted. The output of the flip-flop (7) and the output of the comparator (9) are input to an AND circuit 00, and only the defect signal of the required inspection area is extracted. The output of the flip-flop (7) becomes a test gate that determines a valid test area. The relationship between each signal is shown in No. 21, where <a> is the reference signal output from the scanner scanning path (1a), (.) is the analog signal output from the inspection head (8), and (C) is the counter (3). ), the count end signal (, d) is the counter (5
) count end signal, (e) is the flip-flop (7
), (f) is the output of comparator (9), (
g) is the output of the AND circuit α1. In the figure, nl
is the number of settings in the preset circuit (4), and n2 is the preset circuit (6).The US laser surface inspection equipment was configured as described above, so when the board to be inspected meandered, the rise of the analog signal waveform and the scanner The phase of the drive circuit's reference signal changes, causing the gate signal and analog signal to be out of phase.
However, the inspection area may also include a portion where the analog signal does not rise, which has the disadvantage of causing malfunction. This is because the width and phase of the gate signal are fixed against changes in the width of the analog signal.

This invention was made in order to eliminate the above-mentioned drawbacks of the conventional method, and by making the phase and width of the gate signal automatically follow the changes in the analog signal, the analog waveform can always be maintained. It is an object of the present invention to provide a laser type surface inspection apparatus in which a gate signal is set within a necessary inspection area to prevent malfunctions.

An embodiment of the present invention will be described below with reference to the drawings. 8th
In the figure, 6! ◇ is a comparator that converts an analog signal into a rectangular wave, 2) is a counter that measures the width of the analog signal waveform by counting the clocks of the clock oscillator (3), and 2) is a counter that measures the width of the analog signal by counting the clocks of the clock oscillator (3). A latch circuit that latches, (c) a counter that counts the set value of (from the rising edge of the analog signal to the preset circuit), and a counter that counts the clock with the set value of (from the rising edge of the analog signal to the preset circuit) as the initial value. , in) is the value latched in the latch circuit (c) and the counter (e)
A comparator that compares the count values of , and outputs a signal when the values of the latch circuit @ and the counter (c) match. 2) is a flip-flop operated by the output signals of the counter (c) and comparator (1), and 2) is an AND circuit that operates the inspection head (
8), the analog signal is extracted from the defective signal by the comparator (9), the output of the flip-flop), the analog signal region selection reference square wave signal from the scanner drive circuit Qf9, and °: 222. 7. . ym*tthe. . , 2 becomes a rectangular wave, and the width W of the rectangular wave is used as a counter) to count and measure the clock of the clock oscillator (3). This measured value is input to the latch circuit.

Tsuchi. On the other hand, the counter counts the set value α from the rising edge of the output rectangular wave of the comparator Qp to the preset circuit using a clock, outputs the output after the count is completed, and sets ) to the flip-flop. Comparator Q with the preset value β of circuit ■ as the initial value
◇The clock is counted from the rising edge of the output rectangular wave, and the comparator (2) compares the latch data of the latch circuit, that is, the analog signal 1m value from one scan ago, and outputs an output signal when they match, and outputs a signal from the flip-flop. Reset the kan and at the same time reset the counter (e). Therefore, the output of the flip floater (2) becomes a rectangular wave that rises at a point delayed by α from the rise of the analog signal and falls at a point β minutes before the fall of the analog signal width during the previous scan. Become. That is, the analog signal width of the previous scan is always referred to and controlled so that the gate signal is always placed inside it. A comparator (9) compares this gate signal with the analog signal from the inspection head (8).
The signal extracted through the scanner drive circuit (1
By adding the reference signal for selecting the analog signal region outputted from b) to the AND circuit 0), only necessary defects can be extracted without shifting the phase and width of the analog signal and the gate. FIG. 4 shows the relationship between each signal. (a) is the output signal from the scanner drive circuit (1b), (b) is the analog signal from the inspection head (8), (c)
) is the output of the comparator (c), (d) is the output of the counter (c), (e) is the output of the counter (c), (f) is the output of the flip-flop), and (g) is the output of the comparator (c). 9) output, (
h) is the output of ) to the AND circuit.

Note that although the preset circuit is not particularly defined in the second embodiment, the same applies to digital switches or software setting of registers by the CPU. In addition, as shown in Fig. 6, the data E is latched into the preset device 0◇ of data E, the comparator) and the switching circuit (in the case of W, the latch circuit), and the analog signal width is By setting a limit on the reduction, A below E can be detected as a break in the board edge or a large dirt defect from the board edge.As described above, according to the present invention, the defect detection area within the analog signal width can be detected. Since it is configured to automatically follow changes in analog signal width due to meandering of the inspection plate or gradual fluctuations in scanner amplitude, malfunctions can be eliminated and a highly reliable device can be obtained.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of a signal processing section of a conventional laser surface inspection device, Fig. 2 is a diagram showing an example of a signal waveform in the case of Fig. 1, and Fig. 8 is a signal processing according to an embodiment of the present invention. FIG. 4 is a diagram showing an example of a signal waveform in the case of FIG. 8, and FIG. 5 is a circuit diagram showing another embodiment of the present invention. Series...Comparator, (a)...
・Counter, (2)...Latch circuit, (
C)・・・・・・Counter, (B)・・・・・・
・・・Preset circuit, (a) ・・・・・・Counter, (b) ・・・・・・preset circuit, (2
)・・・・・・Comparator, (E)・・・・・・・・・
・Flip-flop Note that the same numbers in the figures indicate the same or equivalent parts. Agent Makoto Kuzuno - Figure 1 Figure 2 (>) - 11111111 --- 1--11 Figure 3 Figure 4 (h)

Claims (2)

[Claims] (1) A first comparator that converts an analog signal from the inspection head of a part of the sensor into a rectangular wave, a clock oscillator and a 10th counter for measuring the width of the output of this first comparator, a latch circuit for latching the data of the first counter; a second counter that counts the number of clocks of the first setter from the rising edge of the output of the first comparator and outputs a signal; a third counter whose initial value is the value of the setter; a second comparator that outputs a signal when the value of the third counter becomes equal to the data of the latch circuit; and the second comparator. and a flip-flop circuit that is reset and set by the output of the 20th counter and set by the output of the 20th counter. (2) - The inspection area is always set within a predetermined analog signal width by referring to the analog signal width before scanning, so that even if the analog signal width changes, the inspection area changes accordingly. A laser surface inspection device according to claim 1, characterized in that: