JPS5999238A - Surface inspecting device - Google Patents

Abstract

PURPOSE:To decide on the kind of a flaw from the distribution state of a signal outputted after a height and then a breadthwise decision on the histogram of a body to be inspected, by making those decision on the histogram at specific conveyance-directional intervals of length in every breadthwise division. CONSTITUTION:A pulse corresponding to the specific conveyance-directional length of the body 11 to be inspected is outputted by a pulse generator 20 and counted by a counter 144 to sends an operation command to a control circuit 145. The control circuit 145 starts reading data out of a buffer memory 143 and the data is compared by a height deciding circuit 15 with a set value H to output a signal to the output terminal of a comparing circuit when the data is larger than the set value. The output signal is counted by the counter 161 of a width deciding circuit 16 and the counted value is compared with a width set value W by a comparing circuit 162, which outputs a signal when the counted value is smaller than W. The width deciding circuit 16 generates a signal in response to a linear flaw pattern and a dot flaw pattern, and the signal is ceased in case of a dirt pattern. When the counted value is larger than a set value N, a decision on the linear flaw pattern is made, and the decision on the dirt pattern is made by the output of a detecting circuit 17.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a surface inspection device for inspecting the surface of an object to be inspected, such as a steel plate or an aluminum plate, and in particular, to an apparatus for accurately detecting the types of flaws on the surface of an object to be inspected. The present invention relates to a surface inspection device for making a determination.

[Technical background of the invention and its problems]

Conventional devices of this type use an industrial television camera to optically scan the transported object from one end to the other in the width direction, capturing a surface image of the object. , the analog signal of the surface image is binarized and further divided in the width direction to obtain quantized data. After comparing and adding the quantized previous data and current data to create a histogram, the histogram is read out for a certain length of the inspected object for each division, and the number of consecutive ``1'' is the highest. The type of flaw was determined based on the width and area of the representative flaw.

However, the above-described flaw determination means, for example,
In the case of linear flaw pattern 1, which is a collection of many linear flaws as shown in the figure (,), arrow A in the histogram shown in Fig. 2(b) is evaluated as a representative flaw, so many lines other than A are evaluated. No defects can be detected.

In addition, as shown in Figure 4 (,), there is a
If the number of linear flaws 3 is included, the arrow mark in the histogram shown in Fig. 4(b) is evaluated as a representative flaw, so other dot-like flaws are completely ignored, and the type of flaw cannot be determined. There is a drawback that it cannot be accurately determined.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a surface inspection device that accurately determines the type of flaw on an object to be inspected online and in real time.

[Summary of the invention]

The present invention creates a histogram for a certain length of the object to be inspected, performs a height judgment on the fixed length of the object to be inspected in the conveyance direction for each divided section in the width direction, and then performs a judgment in the width direction, This is a surface inspection device that determines the type of flaw on the object to be inspected from the distribution state of the signals outputted through both of these determinations.

[Embodiments of the invention]

FIG. 1 is a diagram showing an embodiment of the apparatus of the present invention. This device includes an imaging device 12 that obtains a surface image of the object 11 by optically scanning the object 1 to be inspected, which is transported in the direction of the arrow, from one end in the width direction to the other end, and an output from the imaging device 12. Binarize and further quantize the analog signal of the surface image
Valueization-quantization circuit 13 and this binarization-quantization circuit 13
A histogram creation circuit 14 that creates a histogram from the binarized data obtained by the above, and a height judgment circuit 15 and a width judgment circuit 16 that judge the height and width of the binarized data read out from this circuit 14. It is provided with a peak number detection circuit 17 that counts signals that have passed through circuits 15 and 16, and a calculator 18 that determines the type of flaw from the output of this circuit 17. The binarization-quantization circuit 13 is connected to the imaging device 12
Binarized data is obtained by discriminating the wave height of the analog signal of the surface image output from the converter based on a predetermined level, and pulses from a pulse generator 20 connected to a roller 19 installed on the conveyance line are obtained. Then, the object to be inspected 11 is divided into appropriate pixels in the width direction and quantized. Next, the histogram creation circuit 14 includes an addition circuit 141, a main memory 142, and a buffer memory 143.
, a counter 144 for counting pulses from the arm pulse generator 20, and a control circuit 145. This adder circuit 141 integrates the binarized data by comparing the binarized data of the previous scan and the binarized data of the current scan, which are divided in the width direction of the object 11 to be inspected, for each division. In addition, the main memory 142 sequentially stores the accumulated data obtained by the adder circuit 14 in one cycle by inputting a clock CP corresponding to the number of divisions in the width direction of the object 11 to be inspected, A histogram of flaws accumulated over a certain length in the conveyance direction is created and stored. The buffer memory 143 has a function of temporarily storing the histogram in the main memory 142 and outputting histogram data for a fixed length in the transport direction of the object to be inspected 11 for each division in the width direction based on a read command from the control circuit 145. have. The counter 144 provides a signal to the control circuit 145 when it receives a number of pulses from the pulse generator 20 corresponding to the fixed length of the object 11 in the transport direction.

The height determination circuit 15 includes a comparison circuit 15 which compares the histogram data read from the buffer memory 143 with a predetermined height setting value H, and outputs the histogram data exceeding the height setting value H. , this comparison circuit 151
and an AND date 152 that outputs the output data every time the clock CP is input.

Further, the width determination circuit 16 has a counter 161 and a comparison circuit 162, and counts the signal output from the AND-DART 152 with the counter 161 to obtain the width value of the flaw on the surface of the object to be inspected. When the width value is within the width setting value W, for example, the comparison circuit 162 outputs a signal. The peak number detection circuit 17 includes a counter 171 that counts the number of signals output from the comparison circuit 162, and a comparison circuit 172 that determines whether the count value of this counter 1710 is greater than or equal to a set value N. .

Next, the operation of the device configured as above will be explained.

The object to be inspected 11Fi is being transported in the direction of arrow A on the transport line, and at this time, the imaging device 12 installed on the transport line optically scans the surface of the object to be inspected 11 from one end in the width direction to the other end. The surface image of the object to be inspected 11 is captured every scan, converted into an analog signal, and then converted into a binary signal.
It is sent to the quantization circuit 13. This binarization-quantization circuit 1
3 compares and binarizes the analog signal of the surface image inputted from the imaging device 12 at a predetermined setting level, and also converts the analog signal of the surface image inputted from the imaging device 12 into the inspected object 1 by receiving the pulse outputted from the pulse generator 20. The quantized binary data is divided into appropriate pixels in the width direction of the pixel, and the quantized binary data is added to the adding circuit 141.
sequentially supplied to In the adder circuit 141, the main memory 14
The binarized data for the previous one scan input from 2 and the binarized data for the current one scan input from the binarization-quantization circuit 13 are compared and added, and the added value is calculated. is stored in the subsequent main memory 142.

The signal processing as described above is performed for a certain length of the object to be inspected 11 in the transport direction, and after creating histograms as shown in FIG. 2 6) to FIG. 4(b), the buffer memory 14
Moved to 3. In this case, the surface of the object to be inspected 11 has linear flaws and
If there is a mother turn 1, dirt/mother turn 4, spot flaws or turn 2, the buffer memory 143 will have a message as shown in FIG. 2(b).
, FIG. 3(b), and FIG. 4(b), histogram data will be stored.

Thus, when a number of pulses corresponding to a certain length of the object to be inspected 11 in the transport direction are outputted from the pulse generator 20, the counter 144 counts the number and gives an operation command to the control circuit 145. At this point, the control circuit 145 starts reading the histogram data from the buffer memory 143. In this case, the object to be inspected 1 for each division in the width direction of the object to be inspected 11
The data is read out at regular intervals for a constant length in the transport direction. The data read from the buffer memory 143 is compared with the height setting value H in the comparison circuit 15 of the height determination circuit 15, and a signal is outputted to the output terminal of the comparison circuit 151 only when it is equal to or greater than the setting value H. At this time, the height setting value H is set to Hl or H as shown in FIGS. 2 to 4.

Either one or continuously variable, or furthermore, both the height determination circuit with H1 and the height determination circuit with H2 may be connected to the histogram creation circuit 14.

Hereinafter, for convenience of explanation, H is used as the height setting value.

We will explain the case using . In this case, 9- When the linear flaw in Fig. 2 is 4 turns 1, the comparator circuit 151
A large number of signals are generated from the turn 4, and a large number of signals are similarly generated at the dirt i4 turn 4 in FIG.

In the case of point-like flaw pattern 2 in FIG. 4, only one signal is generated. The signal outputted from the comparison circuit 15 in this manner passes through the AND/DART 152 which is turned on by the high speed clock CP, and is counted by the counter 16 of the width determination circuit 16.

This counter 161 is reset, for example, when the output terminal of the comparison circuit 15 falls. The count value of the counter 161 is sent to a comparison circuit 162, where it is compared with the width setting value W, and when the count value is within the width setting value W, a signal is output. Therefore, the width determination circuit 16
A signal is generated when there is a linear flaw pattern 1 and a dotted flaw pattern 2, and it is erased when it is a dirt pattern 4 as shown in FIG. The signal outputted from the width judgment circuit 16 in this way is counted by the counter 17 of the subsequent peak number detection circuit 17, but this count value is further compared with a set value N, and when it is greater than or equal to N, a calculator Linear flaw pattern 1 at 18
It is determined that Suppose that the height judgment circuit 15 has a height setting value H1, the width judgment circuit 16 outputs a signal within the width setting value W, and the peak number detection circuit 1 outputs a signal of a setting value N.
7 to FIG. 1, it is possible to determine the dot pattern 2 based on the signals output from these circuits. Furthermore, if the width setting width W is increased and a signal is output from the width determination circuit 16 when the width is greater than or equal to N, it is possible to determine a dirt pattern based on the output of the peak number detection circuit 17.

〔Effect of the invention〕

As described in detail above, according to the present invention, the data obtained by binarizing and quantizing the surface image in the width direction of the object to be inspected, and converting it into a histogram for a certain length in the transport direction of the object to be inspected, is divided during quantization. The height is determined for each section, the width of the histogram data generated in the width direction is determined, and the signals obtained as a result of the height and width determination are counted to know the distribution state of the flaw, so the type of flaw can be determined. It is possible to determine the correct answer online and in real time, and it is also possible to accurately determine the degree of linearity and dot-likeness.

Furthermore, since the peak number can be counted by the peak number detection circuit and immediately used for determination, a surface inspection apparatus that can perform high-speed processing can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a surface inspection apparatus according to the present invention, and FIGS. 2 to 4 are diagrams showing nine turns of flaws on the surface of an object to be inspected and their histograms. 11... Inspection object, 12... Imaging device, 13...
Binarization-quantization circuit, 14... Histogram creation circuit, 15... Height judgment circuit, 16... Width judgment circuit, 1
7...Peak number detection circuit. Applicant's agent Patent attorney Takehiko Suzue Figure 2
Figure 3 Figure 4 223-

Claims (1)

[Claims] An imaging device that optically scans the surface image of the object to be inspected by optically scanning it from one end of the object to be inspected in the width direction to the other end, and a binary analog signal of the surface image in the width direction obtained by this imaging device. A binarization-quantization circuit divides and quantizes in the width direction using pulses output from a pulse generator connected to the rollers of the conveyance line, and the output from the binarization-quantization circuit A histogram creation circuit that creates a histogram for a certain length in the transport direction of the object to be inspected by comparing and adding the binarized data of the previous scan and the binarized data of the current scan; A height judgment circuit reads out a certain length in the transport direction for each division, compares it with a predetermined height setting value, and outputs a signal when the histogram is high, and counts the signal output from this height judgment circuit. and a width judgment circuit that compares the obtained width value with a predetermined width setting value and outputs a width judgment signal, and determines the type of flaw by counting the number of signals output from this width judgment circuit. A surface inspection device characterized by: