JP2941411B2 - Surface inspection equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial field of application) The present invention relates to a method in which a surface of a belt-shaped object traveling in contact with a roll or the like is photoelectrically moved in a width direction at a position in contact with the roll or the like. TECHNICAL FIELD The present invention relates to a surface inspection apparatus for detecting defects by scanning.

(Prior Art) FIG. 4 shows a typical conventional structure of this type of surface inspection apparatus. The long strip 1 to be inspected runs in contact with the roll 2. Since the strip 1 does not vibrate or bend at the position in contact with the roll 2, photoelectric scanning is performed at this position. That is, the surface of the strip 1 in contact with the roll 2 is illuminated by the light source 3, the reflected light is received by the light receiver 4, and the strip 1 is scanned in the width direction. There are various types of scanning, such as a flying spot, a flying image, and a one-dimensional camera.

Since the photoelectric scanning is performed over a range slightly longer than the width of the strip 1, the surface of the roll 2 is also scanned. If there is the same reflected light from the surface of the roll 2 as that from the band 1, it is impossible to distinguish whether the inspection signal is the inspection signal of the surface of the roll 2 or the inspection signal of the surface of the band 1 in the processing system of the received light signal. Therefore, in order to sufficiently reduce the intensity of the reflected light from the roll 2 entering the light receiver 4, a light-shielding device 5 is provided so that the illumination light from the light source 3 impinges on the roll 2 which is not covered with the strip 1. I try not to. That is, the light-shielding device 5 is provided so that the portions of the roll 2 exposed on both sides of the strip 1 are shaded. In this way, the level of the reflected light at the portion of the roll 2 becomes sufficiently small, and can be reliably distinguished from the level of the reflected light from the strip 1.

(Problem to be Solved by the Invention) In the above-described conventional technology, if the strip 1 traveling in contact with the roll 2 does not fluctuate at all in the width direction, the object can be achieved with a simple light shielding device 5. it can. However, the strip 1 often fluctuates in the width direction as it travels, and does not irradiate the exposed surface of the roll 2 with illumination light.
In addition, it was practically difficult to keep the surface of the band 1 out of the shadow.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a surface inspection apparatus that scans a strip in the width direction at a position in contact with a roll or the like. Another object of the present invention is to keep the level of the reflected light from the surface of the roll or the like sufficiently small with respect to the level of the reflected light from the surface of the strip.

[Configuration of the Invention] (Means for Solving the Problems) In order to achieve the above object, a surface inspection apparatus of the present invention comprises:
In a device that inspects the surface by optically scanning the surface of a strip running in contact with a roll or the like in a width direction at a position in contact with the roll or the like, the color of the surface is an illumination light source for inspection. A roll or the like that is complementary to the color, travel amount detection means for detecting the travel amount of the strip, scan start detection means for detecting the start of the scan, and receiving a scan start from the scan start detection means. Scanning result input means for inputting a scanning result for each predetermined traveling amount of the band based on a detection result of the traveling amount of the band by the traveling amount detecting means, and dividing a width of the scanning into an area having a predetermined width. And counting means for counting the frequency at which the level of light reflected from the strip exceeds a predetermined level for each of the divided areas for the scanning result for each predetermined travel distance from the scanning result input means. I do.

(Operation) The rolls and the like are exposed on both sides of the belt-like object to be inspected. Illumination light for scanning also hits the roll, and reflected light from the roll enters the light receiver and is scanned. Since the color of the surface of the roll or the like is complementary to the color of the illumination light, the level of light reflected from the surface of the roll or the like becomes sufficiently small. In addition, by dividing the width of the optical scanning into regions of a predetermined width and counting the frequency of abnormal reflection from the scanning band for each of the divided regions, information on the surface condition of the band is obtained. Have collected.

(Example) When a red light source such as a He-Ne laser is used as an illumination light source for scanning, the surface color of a roll or the like is selected from blue or green.

Further, it is more preferable to provide a polarizing filter in a light receiver for scanning so as to attenuate light reflected from a surface such as a roll.

In the output of the photodetector for scanning, if the reflected light level from the surface of the roll or the like is kept sufficiently small with respect to the reflected light level from the surface of the belt-like object to be inspected,
It is possible to easily and accurately distinguish an effective portion (a test signal of a strip) and an ineffective portion (a portion protruding from the strip) of the received light output. Hereinafter, signal processing for that will be described.

In FIG. 1, 1 is a strip, 2 is a roll, 3 is an illumination light source, and 4 is a light receiver. As described above, the color of the surface of the roll 2 is complementary to the color of the illumination light source 3. . Therefore, at the output a of the light receiver 4, the level of the scanning portions A and C of the roll 2 is sufficiently lower than the level of the scanning portion B of the strip 1. Therefore, if the appropriate threshold value b from the setting unit 6 and the light receiving output a are compared by the comparator 7 to perform level discrimination, an accurate gate signal c is obtained as shown in FIG. By controlling, the signal d of the scanning portion B of the strip 1 can be extracted.

Another example of signal processing is shown in FIG. 2 and FIG. Here, the output a of the light receiver 4 is differentiated by the differentiating circuit 9, and the differentiated output e is compared with the positive / negative thresholds + Vs, -Vs from the setter 11 by the comparators 10a, 10 to discriminate the level.

The positive differential pulse f output from the comparator 10a includes one edge signal E1 of the strip 1 and
The negative differential pulse g output from 10b includes the other edge signal E2 of the strip 1.

On the other hand, a scanning start signal h is obtained by the sensor 12 constituting the scanning start inspection means, and a signal synchronized with the running of the strip 1 is obtained from the pulse generator 13. The output of the pulse generator 13 is frequency-divided by the frequency divider 14 to generate a signal for each minute constant pitch 1 and a signal for each constant traveling distance L which is relatively large. The memory controller 15 operates in response to the output of the frequency divider 14 and the scan start signal h, and is reset by the scan start signal h. Note that the pulse generator 13 and the frequency divider 14 constitute a traveling amount detecting means.

The memory 16a (16b) has an adder at the input stage, and reads the address of the memory controller 15 every time a positive differential pulse (negative differential pulse) is output from the comparator 10a (10b), and performs positive differential with respect to the previous value. If there is a pulse (negative differential pulse), "1" is added and stored. In other words, it works as a multi-addition type in which addition is performed in address units.

The timing of addition and storage in the memory 16a (16b) is determined at every fixed pitch 1 obtained by dividing the signal from the pulse generator 13 which generates a pulse in synchronization with the progress amount every time the line progresses by the frequency divider 14. Take the form of sampling and storing. In other words, the contents stored in the memory 16a (16b) are divided in the width direction of the band from the scanning start point by the memory address unit w, and the traveling direction of the band is pitched at every pitch and the flow direction comparator 10a ( This means that the number of output pulses in 10b) is extracted and the oblique shadow is obtained in the flow direction. Here, when the flow direction progress amount L (1 <L) has elapsed, the memory 16a (16b)
This stores the count value for each width position obtained by finely dividing the pulse output of the comparator 10a (10b) in each width direction. The comparators 10a and 10b and the setting device 1
1. The memory controller 15 and the memories 16a and 16b constitute scanning result input means and counting means. When the value advances by a certain value L, the contents of the memory 16a (16b) are sequentially read out according to the address of the address bus, and the contents are set by the positive and negative independent profile comparators 17a (17b).
The address exceeding the set value is compared with the set value of 18a (18b) and latched by the latch circuit 19a (19b). At this time, the latch 19a of the positive polarity latches every time the set value is exceeded, but the latch is prohibited after the address exceeding the set value of the negative polarity. In the integrated profile, the differential pulse is continuously generated at the edge portion of the strip, whereas the dirt and flaws on the roll 2 are difficult to continuously generate the differential pulse. ), Since the integrated value is lower than the edge, the separation can be reliably performed. The latched positive address and negative address are not updated until the next signal of the travel distance L, and the address synchronized with the scanning start signal and the latched address are independently and positively / negatively compared by the comparator 20a (20b). By giving the positive address coincidence point as a set signal and the negative address coincidence point as a reset signal to the gate flip-flop 21 at each coincident point, the output of the flip-flop 21 becomes the correct gate signal c.

If the profile integration value of the edge of the strip and that of the roll 2 are close to each other and the above-mentioned conditions cannot be satisfied, the address bus is separated into two systems, one for the positive polarity and the other for the negative polarity. When reading, the address counter is switched by the bus switching gate, positive data is read by counting down from 1/2 of the memory writing range, and negative data is read by counting up from 1/2 and the first comparison set value is read. The exceeded address may be latched and the flip-flop 21 may be set and reset in the same manner as described above to output the gate signal c.

[Effects of the Invention] As described above in detail, in the present invention, the color of a roll or the like in contact with a strip (inspected object) is selected so as to have a complementary color relationship with the color of an illumination light source for scanning. Because
Even if the strip fluctuates in the width direction on a roll or the like as it travels, the level of light reflected from the surface of the roll or the like is sufficiently higher than the level of light reflected from the surface of the strip in the output of the scanning photodetector. The low state is always maintained, and only the effective portion of the scan output can be accurately extracted by simple circuit processing. In addition, by dividing the width of the optical scanning into regions of a predetermined width and counting the frequency of abnormal reflection from the band by scanning for each of the divided regions, information on the surface state of the band is obtained. Is collected, it is possible to contribute to an accurate inspection of the surface condition of the band.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration and a waveform of an example of a signal processing system in an apparatus adopting the present invention, FIG. 2 is a block diagram showing another example of the signal processing system, and FIG. FIG. 4 is a waveform diagram, and FIG. DESCRIPTION OF SYMBOLS 1 ... Strip | belt-shaped material, 2 ... Roll 3 ... Illumination light source 4, ... Light receiver 5 ... Light shielding device, 6 ... Setting device 7 ... Comparator, 8 ... Gate

Claims (1)

(57) [Claims] An apparatus for inspecting a surface of a belt-shaped object traveling in contact with a roll or the like by optically scanning the surface in a width direction at a position in contact with the roll or the like. A roll or the like that is complementary to the color of the illumination light source, travel amount detection means for detecting the travel amount of the strip, scanning start detection means for detecting the start of scanning, and scanning start detection means. Receiving the start of scanning, scanning result input means for inputting a scanning result for each predetermined traveling amount of the band based on a detection result of the traveling amount of the band by the traveling amount detecting means; and setting the width of the scanning to a predetermined width. Counting means for counting the frequency at which the reflected light level from the strip exceeds a predetermined level for each of the divided areas with respect to the scanning result for each predetermined traveling amount from the scanning result input means. Characterized by having Surface inspection apparatus.