JP2001133413A - Monitoring device for performance of surface-defect inspection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a monitoring device, for the performance of a surface- defect inspection apparatus, by which the generation of a defective product due to the abnormality of the inspection apparatus during an inspection is prevented, by which the productivity of the inspection apparatus can be maintained and by which the guarantee of a quality can be enhanced sharply. SOLUTION: In this surface-defect inspection apparatus, the surface of an object 2 to be inspected is subscanned so as to be irradiated with a laser beam from a laser light source 11, and a surface defect such as a flaw part, a specific part or the like which is generated on the surface of the object 1 to be inspected is detected on the basis of reflected light from the object 2 to be inspected. A laser quantity-of-light detector 17 which is installed within the laser-beam subscanning width of the laser beam irradiated from the laser light source 11 and outside an effective measuring range is provided. A monitoring part 25 which monitors the output of the laser quantity-of-light detector 17 is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a performance monitoring apparatus for a surface defect inspection apparatus, and more particularly to an apparatus for monitoring the performance of an optical system and a signal processing system for detecting a surface defect generated on the surface of an inspection object.

[0002]

2. Description of the Related Art In a continuous production line for thin steel sheets and the like,
Optical surface defect inspection devices for inspecting flaws and unique parts are generally used. In order to maintain the accuracy and performance of this optical surface defect inspection device, a standard plate with holes and black lines is generally used as a means to periodically stop and inspect the surface defect inspection device. I've been. However, in a performance verification unit of a surface defect inspection apparatus that is regularly performed, when a defect in accuracy performance is found, a considerable amount of products have already been shipped. In order to avoid this, it is necessary to frequently interrupt the inspection of the surface defect inspection apparatus for verification, which is not practical.

For this reason, a self-diagnosis function capable of constantly monitoring the surface defect inspection apparatus has been conventionally provided. However, this self-diagnosis function is not provided in an optical surface defect inspection apparatus.
Mainly, abnormality monitoring related to electrical signal processing after the output of the photomultiplier in the head. The maintenance and management of the accuracy and performance of such an optical surface defect inspection apparatus is very important from the viewpoint of preventive maintenance.

[0004]

However, among the maintenance and management of the accuracy and performance of the optical surface defect inspection apparatus, there has hitherto been a method of monitoring an abnormality relating to the electrical signal processing after the output of the photomultiplier in the head. However, there is no method for constantly managing the performance of the optical system before the photomultiplier in the head. as a result,
As a result, defective products are shipped without being noticed. Also,
Even if you notice at this time, because it is a periodic inspection, products within the inspection cycle are not guaranteed to have been inspected sufficiently for products that are well known, and inspections must be performed retroactively to the previous inspection again. Absent.

The present invention has been made to solve these problems, and it is possible to prevent the occurrence of defective products due to an abnormality in an inspection apparatus during inspection, maintain the productivity, and dramatically improve the quality assurance. An object of the present invention is to provide a performance monitoring device for a defect inspection device.

[0006]

In order to solve the above-mentioned problems, the surface of the object to be inspected is sub-scanned and irradiated with laser light from a laser light source, and the surface of the object is inspected based on the reflected light from the object. The performance monitoring device of the present invention, which is applied to a surface defect inspection device that detects a surface defect such as a flaw portion or a unique portion generated on the surface of an object, includes a laser light sub-scanning width of a laser beam emitted from a laser light source. It is characterized by comprising a laser light quantity detector installed outside the effective measurement range, and a monitoring unit for monitoring the output of the laser light quantity detector. Therefore, the performance deterioration state of the laser light source can be constantly monitored.

[0007] Further, by providing a light emitting means installed outside the light receiving range of the reflected light from the object to be inspected, and a monitoring unit for monitoring the output of the light receiving unit for receiving the light from the light emitting means,
The performance degradation of the light receiving unit can be monitored. The light-emitting unit is a light-emitting diode that emits light in a strobe manner, and emits light when the light is out of the effective measurement range of one sub-scan, so that it can be constantly monitored even during surface defect inspection.

Further, by providing a simulated flaw generating jig for generating a simulated surface defect on a part of the light receiving range of the reflected light from the inspection object, the simulated flaw generating jig is provided. The performance of the inspection determination can be monitored based on the detection result for the simulated surface defect. The monitoring by the simulated flaw portion using the simulated flaw portion generating jig is performed in the gap of the surface defect inspection of the inspection object, so that the monitoring can be always performed without affecting the inspection even during the surface defect inspection.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A performance monitoring apparatus according to the present invention includes a laser light amount detector installed within a laser light sub-scanning width of a laser light emitted from a laser light source and outside an effective measurement range;
A monitoring unit that monitors the output of the laser light amount detector.

[0010]

FIG. 1 is a diagram showing a configuration of a performance monitoring device of a surface defect inspection device according to one embodiment of the present invention. 1A is a block diagram, and FIG. 1B is a schematic perspective view. In the figure, a surface defect inspection apparatus 1 to which the present embodiment is applied is an apparatus for detecting a flaw or a unique part of a thin steel plate 2. The laser light emitted from the laser light source 11 is scanned by the polygon mirror 12 driven by the motor 13 in the sub-scanning direction on the thin steel plate 2 in the scanning direction 28 via the lens 14a. The light reflected by the thin steel plate 2 is condensed via a lens 14b and a mask 15 to a photomultiplier 16 that can detect weak light with high sensitivity. The photomultiplier 16 photoelectrically converts the received reflected light and outputs an electric signal. The output electric signal is amplified through a signal amplifier 18, the gain is controlled by an automatic gain control circuit (hereinafter abbreviated as AGC) 21 so as to keep the amplitude of the signal constant, and a signal processing unit 22 and a determination processing unit 23 are controlled. The flaws and unique parts of the thin steel plate 2 are detected based on the flaw determination results obtained by the method.

Next, monitoring of the performance of the laser light source 11 in the surface defect inspection apparatus 1 will be described with reference to FIGS. First, the laser light amount detector 17 installed within the laser scan width range of the laser light scanned on the thin steel plate 2 and out of the effective measurement range always detects the light amount of the laser light. The detected output signal is supplied to the analyzer 25, and the trend is managed. The analyzer 25 monitors the state of deterioration of the laser light amount of the laser light source 11, and takes measures such as issuing an alarm when the deterioration occurs. Here, there is also a method of directly monitoring by monitoring the light amount detected by the laser light amount detector 17.

The performance monitoring of the light receiving side in the surface defect inspection apparatus 1 is performed at a part outside the light receiving range of the reflected light from the thin steel plate 2 to the photomultiplier 16, and for example, a MOS FET is used. By switching to the test mode terminal T side of the switch 27 such as an analog switch and applying a fixed voltage, the light emitting diode 20 emits light strobely for a moment outside the effective range of one scan. The voltage of the photomultiplier 16 that has received this strobe-like light is switched from the automatic control mode terminal A side to the test mode T side in conjunction with the strobe-like light emission of the light emitting diode 20, for example, a MOS FE.
The sensitivity adjuster 19 and the AGC 21 are separated by a switch 26 such as an analog switch using T to set a fixed value. By monitoring the output of the photomultiplier 16 at this time, the performance deterioration state of the light receiving side of the surface defect inspection apparatus 1 is monitored, and a countermeasure such as issuing an alarm when the deterioration state occurs is taken.

Further, with respect to the performance monitoring of the light source and the light receiving system in the surface defect inspection apparatus 1, the analyzing apparatus 25 analyzes the output of the laser light amount detector 17 and the output state of the photomultiplier 16 on the light receiving side. It is implemented by analyzing and monitoring.

The performance monitoring of the optical system including the lens system in the surface defect inspection apparatus 1 will be described first. First, within the scan width range of the laser beam emitted from the laser light source 11 and within the effective measurement range or the thin steel plate. The simulated flaw generating jig 24 installed in a part of the light receiving range of the photomultiplier 16 of the reflected light from the second 2 generates a simulated flaw at an arbitrary timing while online, for example, when passing through a joint of coils. I do. The performance deterioration status of the optical system including the lens system of the surface defect inspection device 1 is monitored based on the content of the determination result finally determined by the determination processing unit 23 with respect to the simulated flaw portion, and an alarm is issued when the performance status is reached. Take countermeasures such as issuing Note that the simulated flaw portion generated by the simulated flaw portion generation jig 24 is, for example, a thin linear object, an attenuating plate having an arbitrarily selected transmittance or the like inserted into the optical path of the laser beam. is there. In addition, when passing through the joint portion of the coil as an example of an arbitrary timing during online, the part where the flaw inspection is not required in a certain range including the joint portion of the coil is a normal measurement state at this timing. This is the timing at which the inspection using the simulated flaw can be performed under the same conditions as those described above, that is, as if there is a thin steel plate. Therefore, there is no need to interrupt online for flaw inspection, and productivity can be maintained.

FIG. 2 is a diagram showing output signal waveforms of the photomultiplier 16 and the laser light amount detector 17 of FIG. In the figure, the laser light amount detector 1 shown in FIGS.
7 shows the output a, the waveform b shows the output peak hold value of the laser light amount detector 17, the waveform c shows the output of the photomultiplier 16, and the waveform d shows the output peak hold value of the output of the photomultiplier 16. In the drawing, X indicates an effective measurement range in which a surface defect is inspected, and S indicates a range of one scan. As can be seen from the figure, the laser light amount detector 17 installed on the thin steel plate within the laser scan width range of the laser light for each scan and outside the effective measurement range has the light amount of the laser light as shown by the waveform a. Has been detected. Then, the deterioration state of the laser light amount of the laser light source can be monitored based on the numerical value of the output peak hold value of the laser light amount detector 17 shown in the waveform b. In addition, the output of the surface defect inspection within the effective measurement range X of one scan of the reflected light from the thin steel plate, and the instantaneous out of the effective measurement range X of one scan by the light emitting diode installed outside the light receiving range. During the period, the output of the photomultiplier that has received the strobe-like light because of the strobe-like light emission has a waveform c. Then, the photomultiplier 16 of the waveform d
The performance deterioration status of the photomultiplier 16 can be monitored based on the numerical value of the output peak hold value.

The present invention is not limited to the above embodiment, and needless to say, various modifications and substitutions can be made within the scope of the claims.

[0017]

As described above, according to the present invention,
A laser beam from a laser light source is sub-scanned and irradiated on the surface of the object to be inspected, and a surface that detects a surface defect such as a flaw or a singular part generated on the surface of the object based on the reflected light from the object to be inspected. The performance monitoring device of the present invention, which is applied to a defect inspection device,
It is characterized by comprising a laser light amount detector installed within the laser light sub-scanning width of the laser light emitted from the laser light source and outside the effective measurement range, and a monitoring unit monitoring the output of the laser light amount detector. There is. Therefore, the performance deterioration state of the laser light source can be constantly monitored. For example, in coils that are shipped via a continuous production line for thin steel sheets, etc., the optical surface defect detection device installed in the line can easily monitor the optical system abnormality online, and the surface defect inspection device abnormality It is possible to prevent a defective product from being shipped without noticing it. Moreover, even if you notice an abnormality in the surface defect inspection equipment as in the past, it is a periodic inspection, so there is no need to inspect the products in the inspection cycle retroactively to the previous inspection again, and productivity has been greatly improved. , The quality assurance is dramatically improved.

Further, by providing a light emitting means provided outside the light receiving range of the reflected light from the object to be inspected, and a monitor for monitoring the output of the light receiving unit for receiving the light from the light emitting means,
The performance degradation of the light receiving unit can be monitored. The light-emitting unit is a light-emitting diode that emits light in a strobe manner, and emits light when the light is out of the effective measurement range of one sub-scan, so that it can be constantly monitored even during surface defect inspection.

Further, by providing a simulated flaw generating jig for generating a simulated surface defect on a part of the light receiving range of the reflected light from the inspection object, the simulated flaw generating jig is provided. The performance of the inspection determination can be monitored based on the detection result for the simulated surface defect. The monitoring by the simulated flaw portion using the simulated flaw portion generating jig is performed in the gap of the surface defect inspection of the inspection object, so that the monitoring can be always performed without affecting the inspection even during the surface defect inspection.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of an optical system performance maintenance management mechanism of a surface defect inspection apparatus according to one embodiment of the present invention.

FIG. 2 is a diagram illustrating output signal waveforms of the photomultiplier and the laser light amount detector of FIG. 1;

[Explanation of symbols]

1; surface defect inspection device; 2; thin steel plate; 11; laser light source; 12; polygon mirror; 13: motor;
4b; lens, 15; mask, 16; photomultiplier, 17; laser light amount detector, 18; signal amplifier, 1
9; sensitivity adjuster, 20; light emitting diode, 21; automatic gain control circuit, 22; signal processing unit, 23;
4; Simulated flaw generation jig, 25; Analysis device, 26, 27;
Switch, 28; scan direction.

Claims (6)

[Claims] 1. A laser beam from a laser light source is sub-scanned and irradiated on the surface of an object to be inspected, and a surface such as a flaw or a peculiar portion generated on the surface of the object based on reflected light from the object to be inspected. In a surface defect inspection device that detects defects, a laser light amount detector installed outside the effective measurement range within the laser beam sub-scanning width of the laser light emitted from the laser light source, and the output of the laser light amount detector is monitored A performance monitoring device for a surface defect inspection device, comprising: 2. The surface of an object to be inspected is irradiated with a laser beam from a laser light source by sub-scanning the surface of the object to be inspected. A surface defect inspection device for detecting a defect, comprising: a light emitting unit installed outside a light receiving range of reflected light from an object to be inspected; and a monitoring unit monitoring an output of a light receiving unit that receives light from the light emitting unit. A performance monitoring device for a surface defect inspection device, characterized in that: 3. The performance monitoring device according to claim 2, wherein the light emitting unit is a light emitting diode that emits light in a strobe light. 4. The performance monitoring device for a surface defect inspection device according to claim 2, wherein the light emitting unit emits light when the light is out of an effective measurement range of one sub-scan. 5. A surface such as a flaw or a singular part generated on the surface of the inspection object based on the reflected light from the inspection object by irradiating the surface of the inspection object with the laser light from the laser light source in a sub-scanning manner. In a surface defect inspection device for detecting a defect, a simulated flaw generating jig for generating a simulated surface defect for a part of a light receiving range of reflected light from an inspection object is provided. A performance monitoring device for a surface defect inspection device, wherein the performance of inspection determination is monitored based on a detection result of a simulated surface defect generated by the method. 6. The performance monitoring device for a surface defect inspection device according to claim 5, wherein the monitoring by the dummy defect portion using the dummy defect generation jig is performed in a gap of the surface defect inspection of the inspection object.