JPH01239438A - Flaw inspecting device - Google Patents

Abstract

PURPOSE:To improve the reliability of detection accuracy by performing flaw detection by deciding the outputs of two circuits which calculate the signal differences between two couples of line sensors and a circuit which ORs comparator outputs of two line sensors. CONSTITUTION:The difference between the signals of the lines sensors 1A and 1B is detected by a difference circuit 3A by analog arithmetic operation and a waveform shaping circuit 4A performs detection processing to separate flaws 18A and 18C. Then the signals of the line sensors 1B and 1C are processed similarly to separate flaws 18B and 18D. The signals of the sensors 1A and 1B are converted by comparing circuits 5A and 5B into binary signals, which are ORed by an OR arithmetic circuit 6 to separate a flaw 18E straddling a scanning area. Then flaw signals separated by circuits 4A, 4B, and 6 are decided by a decision circuit 7 and outputted. Consequently, the reliability of the flaw detection accuracy is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a flaw inspection device that detects flaws on the inspected surface of an article in the manufacturing process with high precision.

[Conventional technology]

FIG. 4 is a block connection diagram showing a conventional flaw inspection device disclosed in, for example, Japanese Utility Model Publication No. 47-6397. In the figure, 1 is a line sensor as an image pickup device, and 5 is an output signal from the line sensor 1. to an appropriate slice level (R
ef) is a comparison circuit that performs binarization, and 7 is a determination circuit that determines whether or not there is a scratch from the output signal of the comparison circuit 5. Further, in FIG. 5(a), 14 is the surface to be inspected, and 16 is the field of view of the line sensor 1 when the line is stopped (indicated by diagonal lines in the figure). When the surface to be inspected 14 travels in the direction of the arrow 15, the field of view of the line sensor 1 is converted to the surface to be inspected.
The width W is determined by the distance that the surface to be inspected 14 moves in one scanning time, for example, as shown in FIG. 5(b).

Forms a long effective field of view. Hereinafter, the effective field of view of the line sensor 1 is defined as the field of view converted to the surface to be inspected.

Next, the operation will be explained. Now, if a flaw 18 exists within the effective field of view 17, the signal waveform output from the line sensor 1 will be as shown in FIG. 5(b). When this signal is subjected to binarization processing in the comparator circuit 5, the output signal becomes "1" or "0", and the determination circuit 7 further determines the presence or absence of scratches from the output signal. This inspection method utilizes the fact that the reflected light when a scratch exists within the effective field of view is weaker than the reflected light from a normal surface, and the resolution of flaw detection is the same as that of one line sensor 1. It depends on the area ratio of the scratched portion to the area of the effective field of view 17.

[Problems to be Solved by the Invention] Since the conventional flaw inspection device is configured as described above, it is not possible to determine that a flaw with an area larger than a certain level in the effective field of view 17 is a flaw, and it is possible to treat small flaws as single-shot noise. There were problems such as difficulty in distinguishing between Furthermore, as shown in FIG.
Effective field of view 17a.

17b, then 1
The area ratio of the gap in the effective field of view 17a or 17b decreases, resulting in problems such as difficulty in separation without the area that should be detected.

This invention was made to solve the above-mentioned problems, and is capable of highly reliable detection of changes in flaw patterns smaller than the minimum area determined by the resolution of the line sensor. It is an object of the present invention to provide a flaw inspection device that can detect flaws on a surface to be inspected with high precision regardless of the area.

[Means to solve the problem]

The flaw inspection device according to the present invention overlaps at least one area on the surface to be inspected on which the three line sensors are moving, and places them in the effective field of view together with the areas before and after the area, and the three line sensors output from these line sensors overlap. Two series of signals among the series of signals are binarized by one comparison circuit each, and the outputs of these two series of comparison circuits are logically summed by an OR operation circuit, and on the other hand,
Two of the above three series of signals are considered as one pair, and two pairs of 2
The difference between the signals of the series is determined by a difference circuit, and a determination circuit detects the presence or absence of a flaw on the surface to be inspected based on each output signal of the difference circuit and the OR circuit.

In addition, a flaw inspection device according to another invention of the present invention combines two line sensors, connects a differential circuit to one of them, and an adder circuit to the other, and performs a logical OR operation on each of these outputs. It is configured to be input to the determination circuit together with the output of the circuit.

[Effect]

The two comparison circuits of the present invention ensure that when a scratch larger than the resolution of the line sensor exists on the surface to be inspected across two areas of one effective field of view, all of the scratches can be detected from one of them. Since this is detected as a flaw signal and outputted to the determination circuit, the reliability of flaw detection can be increased.On the other hand, the differential circuit uses two lines out of the three lines of line sensor output as one pair. By taking the difference between two pairs of two series signals, it is possible to reliably separate flaw signals while canceling out isolated noise signals.

Furthermore, since the adder circuit in another aspect of the present invention sums the outputs of the two lines of line sensors, the flaw signal is doubled in the overlapping area within the two effective fields of view, but the noise signal is This makes it possible to separate flaw signals with high resolution.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, IA, IB, and IC are line sensors 2A and 2B whose effective fields of view partially overlap.

2C is a Hasofa amplifier, 3A is two line sensors IA
, a difference circuit that takes the difference between two series of signals obtained by IB, 3B is the same (a difference circuit that takes the difference between two series of signals obtained from two line sensors IB and IC, 4A, 4B is a difference circuit 3A) , a waveform shaping circuit that shapes the waveform of the output signal from 3B, 5A and 5B are comparison circuits that binarize the output signals from the two line sensors IA and IB, respectively, and 6 is an output from this comparison circuit 5A and 5B. 7 is a waveform shaping circuit 4A, 4B.
and processing the signals obtained from the OR circuit 6,
This is a determination circuit that determines the presence or absence of a flaw 1, and selects and outputs the determination result to be output according to the output mode set by the output mode setting section 8.

In addition, the three line sensors IA, IB, and IC have effective fields of view 17A and 17, respectively, as shown in FIG. 2(a).
B, 17C are installed in parallel so that each 172 overlaps, so line sensors IA, IB, IC
is the area (a+b) and the area (b + c).

Area (c+d) is its effective field of view 17A, 17B, 17C
shall be. In addition, as shown in FIG. 2(b), flaws 18A, 18B, 18C, 18 on the surface to be inspected 14 moving in the direction of arrow 15 are detected by three line sensors IA, IB, and IC.
When D is scanned, the signal obtained via the buffer amplifiers 2A, 2B, and 2C is e I+82 as shown in FIG. 2(c).
+eff.

Next, the operation will be explained.

First, line sensors IA and IB are placed on the surface to be inspected 14.

18A flaw with a size less than the resolution of each IC
, 18B, 18C, and 18D are present.

When the difference between the two series of signals el+eZ obtained via the line sensors IA and IB is subjected to analog calculation by the difference circuit 3A, the output signal becomes e4 shown in FIG. 2(c). At this time, the signal e4 is equivalent to the signal obtained from the area (a+c) due to the area (a+b)-area (b+c), and the signal corresponding to the area is erased. In addition, since the noise signal in case etc. is canceled by the calculation of (a-c), the signal corresponding to the flaw 18A or flaw 18C existing in the area a or area C shown in FIG. Separated at 4A. On the other hand, line sensor I
B, another two series of signals e2+83 obtained via IC
By performing an analog calculation on the difference between the two by the difference circuit 3B and performing detection processing by the waveform shaping circuit 4B, it becomes possible to separate the flaw 18B or the flaw 18D existing in the area or the area d. In other words, high resolution flaw detection can be achieved. Furthermore, since the next scanning area of the line sensor IA is area (c+d), the same area is inspected twice, resulting in high reliability.

Next, a flaw 18E having a size larger than the resolution of the line sensors IA and IB is found on the inspection surface 14 in areas C and C.
We will explain the case where it exists across . At this time, the line sensor 1A in FIG. 1 detects only a portion of the flaw 18E, and the signal it can detect is small, so the comparison circuit 5A in FIG. 1 cannot separate it. However, since the line sensor IB includes the entire surface of the flaw 18E within its scanning area, it becomes possible for the comparison circuit 5B to separate the flaw signals.

If the output signals from the comparison circuits 5A and 5B are logically summed by the logical sum operation circuit 6 of FIG. 1, it is possible to reliably separate the flaws existing across the scanning area without missing them. In other words, high reliability in flaw detection can be achieved.

Furthermore, in FIG. 1, a waveform shaping circuit 4A.

4B and the flaw signal separated by the OR operation circuit 6, a determination circuit 7 makes a determination and outputs a signal representing the determination result. In this case, in the output mode setting section 8, the function for detecting and separating the two types of scratches is selected by mode setting.

FIG. 3 shows another embodiment of the present invention, and in the figure, 9 is an adder circuit connected to buffer amplifiers 2A and 2B. Also, compared to Fig. 2, the line sensor IC,
The configuration is the same except that the buffer amplifier 2C is omitted.

In this embodiment, the difference circuit 3A calculates the output signals from the buffer amplifiers 2A and 2B, while the adder circuit 9 also performs analog calculations. When the flaws 18A and 18B shown in FIG. 2(b) are present, the output signal from the adder circuit 9 becomes a signal e5 shown in FIG. 2(c). This is a signal for the area (a+2b+c) obtained as the area (a+b) and the area (b+c), and the signal indicating the flaw 18B existing in the area is doubled by the calculation. On the other hand, since the noise signal only doubles, the resulting S/N
This means that the ratio has been improved, and high resolution can be achieved. Furthermore, since the flaw 18A existing in area a can be separated by the calculation of the difference circuit 3A, it is possible to inspect the flaws on the surface to be inspected with high resolution in areas a and b in - times of scanning. can.

〔Effect of the invention〕

As described above, according to the present invention, three line sensors overlap at least one area on the surface to be inspected and are placed within the effective field of view along with the areas before and after the area, and two of these line sensors overlap. Two comparison circuits that perform binarization processing on the signal,
It is equipped with an OR operation circuit for the outputs of these comparison circuits, and two difference circuits that calculate the difference between each pair of signals, with two of the three line sensors as a pair. Based on the output signals of the circuit and the OR circuit, the judgment circuit detects scratches on the surface to be inspected, which reduces the inspection area isometrically and improves the resolution of flaw detection. In addition, it is possible to avoid failure to detect due to division of flaw signals over a plurality of regions due to overlapping effective fields of view, and to improve reliability of detection accuracy.

According to another invention of the present invention, the line sensor is
Since the adder circuit is connected to one of these units, the difference in level between the flaw signal and the noise signal is clear, and the flaw signal can be separated from the noise signal and detected with high resolution. This has the effect of providing a product that can be made more efficient and cost-effective.

[Brief explanation of the drawing]

FIG. 1 is a block connection diagram showing a flaw inspection device according to an embodiment of the present invention, FIG. 2 is an explanatory diagram showing the effective field of view of the line sensor, a flaw pattern on the surface to be inspected, and signal waveforms at each part of the block connection diagram. Fig. 3 is a block connection diagram showing a flaw inspection device according to another embodiment of the present invention, Fig. 4 is a block connection diagram showing a conventional flaw inspection device, and Fig. 5 is a field of view and block connection of a conventional line sensor. FIG. 2 is an explanatory diagram showing signal waveforms in each part of the figure and scratches in two areas. IA, IB, and IC are line sensors, 3A, 3B are differential circuits, 5A, 5B are comparison circuits, 6 is an OR operation circuit, 7 is a determination circuit, and 9 is an addition circuit. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. (Foreign Z name) Procedural amendment (voluntary) Kyo 3.67 Showa Month Day

Claims (2)

[Claims] (1) Three line sensors that overlap at least one area on the moving surface to be inspected, together with the areas before and after it, within the effective field of view, and three series of signals output from each of these line sensors. Two comparison circuits that binarize two of the signal series, an OR operation circuit that takes the logical sum of the output signals of these comparison circuits, and two of the above three series of signals as a pair. , take the difference between two pairs of two series signals 2
A flaw inspection device comprising: a differential circuit; and a determination circuit that determines the presence or absence of a flaw on the surface to be inspected from each output signal of the differential circuit and the OR circuit. (2) Two line sensors that overlap at least one area on the moving surface to be inspected, together with the areas before and after it, within the effective field of view, and two series of signals output from each of these line sensors. two comparison circuits that binarize the data, an OR operation circuit that takes the logical sum of these comparison circuits,
A difference circuit and an adder circuit that calculate the difference and sum of the two series of signals, and a determination circuit that determines the presence or absence of a flaw on the surface to be inspected from each output signal of the difference circuit, the adder circuit, and the OR circuit. A flaw inspection device equipped with