JPH1130591A - Method and device for inspecting film sheet defect - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device for film sheet defect inspection that can precisely inspect an air bubble defect, a foreign matter defect, a pinhole defect, etc., generated when a transparent or translucent film sheet, etc., is manufactured. SOLUTION: On one surface side of a film sheet 3, which travels along two rolls 1 and 2 arranged in parallel at a certain interval, a line type light source 5 is arranged and on the other surface side, a linear array camera 7 is arranged; and a 1st polarizing plate 8 is arranged between the film sheet 3 and line type light source 5 and a 2nd polarizing plate 9 is arranged between the film sheet 3 and linear array camera 7. The deviation angle θ of the polarizing directions of the 1st and 2nd polarizing plates 8 and 9 is set to less than ±20 deg. and a detecting circuit 10 is provided which detects as a defect a dark part signal in the camera output video signal 22 outputted by the linear array camera 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bubble defect generated when a transparent or translucent film sheet or the like is produced,
The present invention relates to a film sheet defect inspection method and a film sheet defect inspection device for inspecting a defect such as a foreign matter defect or a pinhole defect.

[0002]

2. Description of the Related Art When manufacturing transparent or translucent film sheets, various defects such as bubble defects, foreign matter defects, and pinhole defects are caused by various factors in the manufacturing process from the raw material quality and raw material melting to film formation. May occur. Since these defects cause the performance of the final product to deteriorate after the molding process, it is inspected online in the film sheet manufacturing process, and the positions of the defects in the winding direction and the width direction of the film sheet are determined. It is necessary to determine and provide information.

As an on-line inspection during production winding, there is also a method of visually inspecting a running film. However, under natural light, bubble defects and the like are hardly distinguished from normal portions under natural light and cannot be inspected.

On the other hand, a method using a polarizing plate has been proposed as disclosed in Japanese Patent Application Laid-Open No. 6-148095. In this method, the polarization direction of the opposite polarizer is set to a right angle or an arrangement close to a right angle, so that the camera uses the right-angled polarized light component due to the defective portion as an increased light component.

[0005] As a pinhole defect detection device,
A discharge type device that uses a discharge at a pinhole defect portion by providing a voltage application counter electrode device has also been put to practical use.

Further, as disclosed in Japanese Patent Application Laid-Open No. 8-338814, a pinhole defect inspection method using ultraviolet rays has been proposed.

Further, as disclosed in Japanese Patent Application Laid-Open No. 6-18445, a pinhole defect inspection method using a polarizing plate has been proposed. In this method, the polarization direction of the opposite polarizer is set to be parallel or nearly parallel, so that the linearly polarized light passing by the pinhole defect portion is captured by the camera as the light increase.

[0008]

However, among the above-mentioned prior arts, in the technique disclosed in Japanese Patent Application Laid-Open No. 6-148095, the polarizing direction of the opposite polarizer is arranged at a right angle or close to a right angle. The orthogonal polarization due to the uneven molecular orientation of the film sheet increases the formation signal and changes in the amount of transmitted light depending on the location of the film sheet, lowers the S / N ratio between the defect and the formation, making it difficult to discriminate and improving quality. There is a problem that even the small distortion that does not cause a problem causes the increase in the amount of the orthogonally polarized light to be apparent and overdetected.

Also, in a discharge type device using a discharge of a pinhole defect portion by providing a voltage application counter electrode device, if it is desired to determine the position of the pinhole defect in the film sheet width direction, a large number of electrodes and detection circuits are required. Must be prepared,
There is a problem that the inspection apparatus becomes large and the inspection cost increases.

In the technique disclosed in Japanese Patent Application Laid-Open No. 8-338814, a linear array camera having a high video signal conversion sensitivity in the ultraviolet region is not generally available on the market. To increase the sensitivity of the device)
There is a problem that it is very difficult to eliminate the protective glass for protecting D or to make the protective glass into quartz glass, and it is necessary to employ an expensive ultraviolet-compatible camera lens, which increases the inspection cost.

Further, the technique disclosed in Japanese Patent Application Laid-Open No. 6-18445 has a problem that, when an attempt is made to apply the method to a relatively wide film sheet, a large number of cameras must be facilitated and the inspection cost increases. There is.

That is, the number of CCD elements of one camera is 20
When using a 48-bit camera and setting the field of view so that the resolution in the film sheet width direction is about 50 μm with respect to the 1-bit CCD element, the field of view of the entire camera is about 100 mm. In order to inspect the film sheet described above, 20 cameras must be provided, which requires enormous equipment and cost. Also, 1bi
When the resolution in the film sheet width direction is set to about 50 μm with respect to the CCD element of t, the pinhole defect detection performance of about 100 μm is limited due to the characteristics of the camera and the video signal processing circuit.

An object of the present invention is to provide first and second polarizers and a linear array camera for preventing a bubble defect, a foreign matter defect, a pinhole defect, and the like generated when a transparent or translucent film sheet or the like is produced. It is an object of the present invention to provide a film sheet defect inspection method and a film sheet defect inspection apparatus which make various defects to be detected evident by use of the device, make it possible to inspect the defects, and detect the defect up to the film sheet width direction position and the film sheet traveling direction position.

[0014]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a typical structure of a film sheet defect inspection method is as follows. The film sheet defect inspection method of arranging a light source on the other side of the film sheet, disposing a linear array camera on the other side of the film sheet, and detecting defect information from video signals output from the linear array camera, And a first polarizing plate disposed between the light source and the second polarizing plate disposed between the film sheet and the linear array camera, the deviation angle of the polarization direction within ± 20 degrees, The method is characterized in that a dark part signal extracted from a video signal output from a linear array camera is detected as a defect.

A typical configuration of the film sheet defect inspection apparatus according to the present invention is such that a light source is arranged on one side of a film sheet conveyed by a film sheet conveying means, and the other side of the film sheet is conveyed. In a film sheet defect inspection apparatus for locating a linear array camera and detecting defect information from video signals output from the linear array camera, a first polarizing plate disposed between the film sheet and the light source And a second polarizing plate disposed between the film sheet and the linear array camera, wherein a deviation angle of a polarization direction with respect to the first polarizing plate is set within ± 20 degrees, and A detection circuit including a dark signal detection unit for extracting a dark signal from the output video signal and detecting the dark signal as a defect. The features.

According to the above arrangement, the light source is disposed on one side of the running film sheet, the linear array camera is disposed on the other side, and the first polarizing plate is provided between the film sheet and the light source. And a second polarizer is disposed between the film sheet and the linear array camera. The deviation of the polarization direction of the pair of polarizers is set to within ± 20 degrees. By detecting defect information corresponding to a bubble defect, a foreign matter defect, a pinhole defect, and the like from a video signal output from the array camera as a dark portion signal and detecting the defect information, a defect generated in the film sheet can be inspected.

Further, in the detection circuit, a shading correction section is provided before the dark section signal detection section to flatten level unevenness in a video signal corresponding to one scan due to camera lens aberration, film sheet thickness unevenness, and the like. in case of,
Inspection can be performed uniformly within the inspection range.

Further, in the detection circuit, the number of pulses of a camera driving pulse signal from the start of scanning to a defect occurrence portion in a video signal corresponding to one scan is measured to detect a defect position in a film sheet width direction. It is preferable to provide a width direction defect position detection unit.

Further, a length measuring pulse transmitter is provided in contact with a roll which guides the running of the film sheet as a film sheet conveying means, and the detection circuit measures the number of output pulses of the length measuring pulse transmitter to measure the running of the film sheet. It is preferable to provide a defect position detecting section for detecting a defect position in the film sheet traveling direction.

Further, in the detecting circuit, if a video signal level automatic adjusting section for automatically adjusting the light amount of the light source based on the output of the video signal output from the linear array camera and automatically adjusting the video signal level to be constant is provided. preferable.

It is preferable to use a line type halogen light source as the light source.

By setting the angle of deviation of the polarization direction of the pair of polarizing plates to within ± 20 degrees, it is possible to reduce the orthogonal polarization due to the uneven molecular orientation of the film sheet and a small amount of distortion. The change in the transmitted light amount depending on the location can be reduced. In addition, a video signal for a distorted portion inside and around a bubble defect or a foreign matter defect, a distortion around a pinhole defect, or the like can be manifested as a dark portion signal, and the S / N ratio between defect and formation can be improved. .

Further, when the angle of deviation of the polarization direction of the pair of polarizing plates is set to be close to a right angle as in the technique disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 6-148095, uneven molecular orientation of the film sheet and slight small distortion are caused. The polarized light component due to the above or the polarized light component of the defective portion acts as a light-increasing effect. However, as in the present invention, by making the deviation angle of the polarization direction of the pair of polarizing plates parallel or within ± 20 degrees, these perpendicular polarized light components can be used. Since the light is blocked, there is almost no brightening effect.

In the polarization direction setting region of the pair of polarizing plates, the polarization direction of the distortion around and inside the defect such as a bubble defect or a foreign matter defect and the distortion around the pinhole defect is rotated from the linear polarization direction from the light source. Then, the direction becomes a direction away from the polarization direction of the second polarizing plate, and the light does not enter the linear array camera, so that the dark portion signal of the video signal is manifestly expressed.

In practice, foreign matter defects and pinhole defects as well as bubble defects always have a large distortion around the defect body, and the distortion becomes more remarkable as the film sheet becomes thinner.

For example, with respect to a minute pinhole defect having a diameter of 50 μm or less, the distortion around the pinhole defect becomes 100 μm or more, and the distortion around the pinhole defect is reduced to about 100 μm. Even at a resolution, a minute pinhole defect having a diameter of 50 μm or less can be detected.

Therefore, regarding a pinhole defect, it is possible to inspect even a pinhole defect having a resolution lower than the camera resolution by capturing distortion around the pinhole defect as a dark portion signal despite the transmission method.

In the polarization direction setting region of the pair of polarizers, in the case of a pinhole defect which is large with respect to the camera resolution, it is possible to capture the transmission enhancement of the pinhole portion as a bright portion signal. Alternatively, if the number of pinhole defects is smaller than that, the bright portion signal is often buried in the dark portion signal of the surrounding distorted portion, which is not practical.

Further, in the detection circuit, by adding a film sheet width direction defect position detecting section and a film sheet running direction defect position detecting section, two-dimensional positions of various defects generated in the film sheet can be detected. These outputs can be provided as a form print by a personal computer for inspection management (hereinafter simply referred to as a "PC") or the like as defect information of the film sheet.

Further, by adding a shading correction section and a video signal level automatic adjustment section linked to a halogen light source in the detection circuit, defect information of a film sheet can be detected in a more stable state.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a film sheet defect inspection method and a film sheet defect inspection apparatus according to the present invention will be described with reference to the drawings. 1 is a diagram showing a configuration of a film sheet defect inspection apparatus according to the present invention, FIG. 2 is a diagram showing a linear array camera and its signal configuration, FIG. 3 is a block diagram showing a configuration of a detection circuit, and FIG. 5 is a diagram showing a signal waveform of each unit of the shading correction unit, FIG. 6 is a block diagram showing a configuration of the inspection interval setting unit, and FIG. 7 is a signal waveform of each unit of the inspection interval setting unit. FIG. 8, FIG. 8 is a block diagram showing a configuration of a dark portion signal detection unit, FIG. 9 is a diagram showing signal waveforms of various parts of the dark portion signal detection unit, FIG. 10 is a block diagram showing a configuration of a film sheet width direction defect position detection unit. 11 is a diagram showing signal waveforms of various parts of the film sheet width direction defect position detection unit, FIG. 12 is a block diagram showing a configuration of the film sheet traveling direction defect position detection unit, and FIG. 13 is a film sheet traveling direction defect position detection unit. FIG. 14 is a block diagram showing a configuration of a video signal level automatic adjustment unit, FIG. 15 is a diagram showing signal waveforms of various units of the video signal level automatic adjustment unit, and FIG. 16 (a) is a film sheet. Diagram showing the state of bubble defects generated inside,
FIG. 16 (b) is a view showing a foreign matter defect generated inside the film sheet, FIG. 16 (c) is a view showing a pinhole defect generated in the film sheet, and FIG. A diagram showing a state of a small distortion portion generated,
FIG. 17A is a diagram showing a video signal waveform output from the linear array camera when the deviation angle θ of the polarization direction between the first polarizing plate and the second polarizing plate is substantially a right angle, and FIG. Figure 17
FIG. 18 (a) is a diagram showing a video signal waveform after shading correction of the video signal, and FIG. 18 (a) shows a first polarizer and a second polarizer.
FIG. 18B is a diagram showing a video signal waveform output from the linear array camera when the deviation angle θ of the polarization direction with respect to the polarizing plate is about ± 50 degrees, and FIG. 18B shows shading correction of the video signal of FIG. FIG. 19 shows a video signal waveform after
FIG. 19A is a diagram showing a video signal waveform output from a linear array camera when the deviation angle θ in the polarization direction between the first polarizing plate and the second polarizing plate is about ± 20 degrees, and FIG. Figure 19
FIG. 3A is a diagram showing a video signal waveform after shading correction of the video signal of FIG.

In FIG. 1, the configuration of the film sheet defect inspection apparatus according to the present invention is a transparent or translucent transparent or semi-transparent sheet running along two rolls 1 and 2 arranged in parallel at a fixed interval as a film sheet conveying means. A linear light source 5 is arranged on one side of the film sheet 3, a linear array camera 7 is arranged on the other side, and the film sheet 3 is photographed by the linear array camera 7 and the linear array camera 7 is photographed.
Equipped with a detection circuit 10 for detecting defect information corresponding to a defective portion such as a bubble defect, a foreign substance defect, or a pinhole defect generated when the film sheet 3 is manufactured from the camera output video signal 22 output from the camera. I have.

Further, a first polarizing plate 8 is disposed between the film sheet 3 and the line type light source 5 on a photographing optical path from the line type light source 5 to the linear array camera 7, and the film sheet 3 and the linear array camera 7 and the second polarizing plate 9
And the angle of deviation θ of the polarization direction of the pair of first and second polarizing plates 8 and 9 is set to an angle within ± 20 degrees. Therefore, the polarization directions of the pair of first and second polarizing plates 8 and 9 are set in substantially the same direction. In the present embodiment, an example in which the deviation angle θ is set to 0 degrees will be described.

The linear light source 5 is controlled by a light source controller 4, and the linear array camera 7 is controlled by a linear array camera controller 6. The defect detection information 11 detected by the detection circuit 10 from the camera output video signal 22 output from the linear array camera 7 is arranged by an inspection management personal computer (hereinafter simply referred to as “inspection management personal computer”) 12. And output.

A length measuring pulse transmitter 13 is provided in contact with the roll 1 or the roll 2, and the length measuring pulse transmitter 13 is provided.
The defect position in the running direction of the film sheet 3 when various defects occur is detected by using the length measuring pulse transmitter output signal 14 of FIG.

Each of the rolls 1 and 2 has a diameter of 100 mm.
φ has a length larger than the width of the film sheet 3 by a predetermined dimension, is arranged in parallel with each other at an interval of 259 mm, and has a mirror-finished surface.

The film sheet 3 is made of an aramid film sheet having a width of 250 mm and a thickness of 4.5 μm, and the inspection section facing the linear array camera 7 at a running speed of 4 m / min by a separate winding mechanism is applied to the rolls 1 and 2. Run horizontally along.

The line-type light source 5 was configured as a line-type halogen light source using Linear Bright (transmission light) PDL-S manufactured by PI Japan. In this line type light source 5, a quartz adapter 16 and a cylindrical quartz rod 17 are linearly mounted on a halogen lamp 15, and the cylindrical quartz rod
With this internal reflection film structure, a strong and uniform light amount can be emitted in a line shape along the longitudinal direction of the cylindrical quartz rod 17.

In the case of this line type light source 5, the luminance is 10 times or more that of the fluorescent lamp, and the linear array camera 7 scans the CCD (charge coupled device) at high speed when the film sheet 3 is running at high speed. It is most suitable as a light source that can provide a necessary light amount in a case where the amount of received light is insufficient.

The line-type light source 5 is configured so that the brightness can be adjusted by a light source controller 4 employing a power supply device PICS-FA-S manufactured by PI Corporation and a linear dimming remote control PRB-0001F.

The detection circuit 10 includes an automatic video signal level adjusting unit 52 shown in FIG. 3, and the control output signal 18 of the automatic video signal level adjusting unit 52 controls the light source controller 4.
, The power 19 of the halogen lamp is adjusted to adjust the light amount 20, and the level of the camera output video signal 22 can be automatically adjusted.

The linear array camera 7 has a micro Nikkor, manual focus type f1 manufactured by Nikon Corporation.
A 05 mm / F2.8 lens 21 was mounted, and the light receiving distance was set so that the inspection field of view corresponding to one scan was 235 mm.
The distance between the film sheet 3 and the lens flange is about 847m
m. The lens aperture was F4.

The first polarizing plate 8 for converting light emitted from the line type light source 5 into linearly polarized light is a polarizing sheet having a thickness of 0.3 mm, a degree of polarization of 99% and a transmittance of 38% manufactured by Panac Co., Ltd. In order to increase the degree of polarization, the two polarizing plates are used in the same polarization direction, the width thereof is 50 mm, and the total length of light emitted from the line light source 5 in the longitudinal direction of the line light source 5 is The length was hanging.

The first polarizing plate 8 was arranged between the line type light source 5 and the film sheet 3 and was set at a distance of about 50 mm from the light emitting surface of the line type light source 5. Further, the distance from the first polarizing plate 8 to the film sheet 3 is about 50 mm.
And The polarization direction of the first polarizing plate 8 was set to the running direction of the film sheet 3.

The second polarizing plate 9 is a dichroic polarizing plate having a thickness of 3.5 mm, a rectangular polarization extinction ratio of 10 ^-4 (0.0001) and a transmittance of 33% when used as a pair, manufactured by Nippon Meles Griot Co., Ltd. Use an effective outer diameter of 76 mmφ
30m directly below the lens 21 attached to the linear array camera 7
It was arranged parallel to the film sheet 3 at the point of m.

In this embodiment, since the polarization direction of the second polarizing plate 9 is parallel to the polarization direction of the first polarizing plate 8, both directions are the same as the running direction of the film sheet 3. Since the second polarizing plate 9 is on the optical path taken by the linear array camera 7, a high-precision dichroic polarizing plate that reduces surface finish and internal distortion and causes no distortion in an image is used.

FIG. 2 shows the linear array camera 7 and its signal configuration. The linear array camera 7 has a CCD element 500b
It used TI5000F manufactured by Excel Co., Ltd.
The linear array camera controller 6 includes a DC power supply 23 for driving the linear array camera 7 and a linear array C
The drive pulse 24 for CD signal processing and the CCD scan start signal 25 are output to the linear array camera 7.

The driving pulse 24 for linear array CCD signal processing is a pulse that is repeatedly output for a time region of 0.2 μs per clock and has a frequency of 5 MHz.
Is a voltage signal of 0 to 5V.

A camera output video signal 22 processed inside the linear array camera 7 and output from the linear array camera 7 is output at a video rate of 10 MHz, and has a time domain of 0.1 μs per 1 bit of the linear array CCD. And the video signal is changed and expressed.

The CCD scanning start signal 25 is a time width pulse of about 2 μs with a repetition time of 2 ms and a voltage signal of 0 to 5 V. The camera output video signal 22, the linear array CCD signal processing drive pulse 24, and the CCD scanning start signal 25 output from the linear array camera 7 are also output to the detection circuit 10. Drive pulse for linear array CCD signal processing
FIG. 2 shows an example of the waveforms of the signal 24, the CCD scanning start signal 25, and the camera output video signal 22, respectively.

FIG. 3 shows the configuration of the detection circuit 10. Detection circuit
Reference numeral 10 denotes a shading correction section 26, an inspection section setting section 31, a dark section signal detection section 40, and a film sheet width direction defect position detection section.
45, a film sheet traveling direction defect position detecting section 50, a video signal level automatic adjusting section 52, and the like.

Hereinafter, the configuration of each part of the detection circuit 10 will be described in detail. First, the configuration of the shading correction unit 26 will be described. FIG. 4 shows a configuration of the shading correction unit 26, and FIG. 5 shows an example of a signal waveform of each unit of the shading correction unit 26.

The shading correction unit 26 is provided for correcting the waveform distortion of the camera output video signal 22 due to the change in the partial orientation unevenness of the film sheet 3 to be inspected or the aberration caused by the aperture setting of the lens 21 mounted on the linear array camera 7. This is provided so that the camera output video signal 22 has a uniform flat level so that defects can be uniformly detected in any part of the inspection range.

The camera output video signal 22 is input to the input stage amplifier 27 at about 1 V as an image average value. The input stage amplifier 27 performs input overvoltage protection, gain adjustment, and zero point adjustment, and transmits a signal to the low-pass filter amplifier 28 in the next stage.

The low-frequency pass filter amplifier 28 is designed to function as a filter inverting amplifier that passes a time constant of about 10 μs, that is, a frequency of about 100 kHz or less.

Accordingly, the raw camera output video signal 22 is a high-speed information change signal of 0.1 μs per bit as shown in the waveform example of FIG. 5 as described above, but the output 28out of the low frequency pass filter amplifier 28 is As shown in the waveform example of FIG. 5, the signal becomes a blunt change.

The output 27out of the input stage amplifier 27 and the output 28out of the low frequency pass filter amplifier 28 are added to the addition circuit 29 of the next stage.
5 is a 29-out waveform shown in FIG. 5, and a portion of the camera output video signal 22 shown in FIG. 5 which greatly changes from the formation noise group in the raw camera output video signal 22 such as a portion 22a. Is pulsed and the output 29ou of the addition circuit 29 in FIG.
Within t, it appears as a short pulse 29a.

This short pulse 29a is a pulse having a possibility of a defect. Also, the first rising edge and the last falling edge of the raw camera output video signal 22 are pulse-shaped, and the short pulse of the output 29out of the adding circuit 29 in FIG.
Appears as 29b, 29c.

This is because the output 28out of the low-pass filter amplifier 28 is slightly delayed in time due to the filter characteristics, and the difference is expressed as a result. However, the portions of the short pulses 29b and 29c are set out of the inspection range by an inspection section setting unit 31 described later.

As shown in FIG. 5, the output 29out of the addition circuit 29 has a signal form that changes like short pulses 29a, 29b and 29c around 0V. In order to facilitate the detection of the dark part signal in the dark part signal detection unit 40 described later in an electronic circuit, and in consideration of the development such as adding an additional image processing device or the like, the output stage amplifier 30 performs zero adjustment, If converted into a signal form raised by the reference voltage, the output of the output stage amplifier 30 in FIG.
It becomes as shown in the waveform example of 30out.

In this embodiment, the reference voltage is set to 1 V, as shown by the output 30out of the output stage amplifier 30 in FIG.
The signal changes like short pulses 30a, 30b, 30c around the reference voltage 1V. Referring to FIG.
The output 30out of the output stage amplifier 30 corresponding to the short pulse 29a, which is a portion where the waveform of the output 29out changes, is a short pulse 30a which is a portion where the waveform of the output 30out has a defect.

Next, referring to FIG. 6 and FIG.
The configuration of 31 will be described. FIG. 6 is a configuration diagram of the inspection section setting unit 31, and FIG. 7 shows an example of a signal waveform of each unit of the inspection section setting unit 31. In the inspection section setting unit 31, a counter 3 is provided with a drive pulse 24 for processing a linear array CCD signal, which is a 0.2 μs repetition period pulse as shown in the waveform example of FIG.
Enter in 3, 37.

The number of CCD elements of the linear array camera 7 is 5
000 bits and a video rate of 10 MHz, but the drive pulse 24 for linear array CCD signal processing is 5 MHz.
Therefore, the total number of clocks for all CCDs is 2500 counts. Therefore, a counter capable of counting up to 2500 is required, and the counters 33 and 37 are 4-digit BCD code output counters.

Further, a CCD scanning start signal 25 which is a 2 ms repetition period pulse as shown in the waveform example of FIG. 7 is input to the retrigger single-shot multivibrator 32. Retrigger single shot multivibrator 32
Is turned on by 25 pulses of the CCD scanning start signal.

Since the counter 33 enters the count mode by the control input of the low level, the counter 33 receives an inverted signal of the output 32out of the retrigger single-shot multivibrator 32, and starts counting the drive pulse 24 for linear array CCD signal processing. , And outputs the data to the next-stage digital comparator 34 in the form of a BCD code.

As the digital comparator 34, one capable of comparing four-digit BCD codes was used. The comparison setting of the digital comparator was performed by the digital switch. The digital switch 35 is set so as to generate a non-inspection section of 10 μs as shown in the waveform example of the output 32out of the retrigger single-shot multivibrator 32 in FIG. 7, and the count data of the digital comparator 34 exceeds the set value. At this time, the output is turned ON.

The output 34 of the digital comparator 34
out the retrigger single shot multivibrator
The retrigger single-shot multivibrator 32 is turned off. Further, the output 32out of the retrigger single-shot multivibrator 32 is input to the single-shot multivibrator 36, and the output 32out of the retrigger single-shot multivibrator 32 is output.
single shot multivibrator 36 when out is OFF
Turns ON.

Since the counter 37 enters the count mode with a low-level control input, the counter 37 receives an inverted signal of the output 36out of the single-shot multivibrator 36, and receives the inverted signal of the output 36out of the single-shot multivibrator 36.
When out is ON, the counter 37 starts counting the drive pulse 24 for linear array CCD signal processing, and stores the data in BCD.
The code is output to the digital comparator 38 at the next stage.

The digital switch 39 is set so that the test section signal 36out, which is the output of the single shot multivibrator 36, generates a test section 36a of 480 μs as shown in the waveform example of FIG. Turns on output 38out when the count data exceeds the set value. And a digital comparator
38 outputs 38out single shot multivibrator
36, the single-shot multivibrator 36
Is turned off.

The count set values of the counters 33 and 37 can be changed by digital switches 35 and 39. As described above, as shown in the waveform example of FIG.
At the output 30out of 26, short pulses 30b and 30c corresponding to the first rising edge and the last falling edge of the raw camera output video signal 22 appear, but deviate from the above-described inspection section 36a.

Next, referring to FIG. 8 and FIG.
Forty configurations will be described. FIG. 8 is a configuration diagram of the dark part signal detection unit 40, and FIG. 9 shows an example of a signal waveform of each part of the dark part signal detection unit 40. In FIG. 8, the dark part signal detection unit 40 includes a comparator 41, a comparison voltage generation circuit 42, an AND circuit 43, and a single shot multivibrator 44.

The output signal 30out of the output stage amplifier 30, which is the result of the shading correction unit 26, and the comparison voltage 42out generated by the comparison voltage generation circuit 42 are input to the comparator 41.
Is turned on when there is a signal having a level lower than the comparison voltage 42out among the output signals 30out. This state diagram is shown in the waveform example of 30out and 42out in FIG.

As a result, the output 41out of the comparator 41 is
As shown in the waveform example of FIG.
a and short pulses 41a and 41 only at a portion corresponding to the short pulse 30c which is the falling portion of the raw camera output video signal 22.
An ON signal consisting of c.

When the output 41out of the comparator 41 and the test period signal 36out of the pulse waveform output from the test period setting section 31 are input to the AND circuit 43, the camera output is obtained as shown in the waveform example of 43out in FIG. A short pulse 43a of only a portion corresponding to the short pulse 30a which is a dark signal portion in the video signal 22 can be extracted. The short pulse 43a becomes the dark part defect detection signal 11a which is darker than the comparison voltage 42out generated by the comparison voltage generation circuit 42.

The short pulse 43a seen in the output 43out waveform of the AND circuit 43 is a short pulse 30a which is a dark signal portion.
Since the pulse width is difficult to catch by the inspection management personal computer 12, the output of the AND circuit 43
43out is once input to the single-shot multivibrator 44, and a pulse having a time length that can be captured by the inspection management personal computer 12 is output as a dark part defect detection signal 11a as shown in the waveform example of FIG. The single-shot multivibrator 44 is composed of a 74LS123 and a CR circuit, and the pulse width of the dark portion defect detection signal 11a output from the single-shot multivibrator 44 is extended to about 0.5 seconds.

Next, the structure of the film sheet width direction defect position detecting section 45 will be described with reference to FIGS. 10 and 11. FIG. FIG.
FIG. 11 is a configuration diagram of the film sheet width direction defect position detection unit 45, and FIG. 11 shows an example of a signal waveform of each unit of the film sheet width direction defect position detection unit 45. As shown in FIG. 10, the film sheet width direction defect position detecting section 45 inputs the linear array CCD signal processing drive pulse 24 which is a 0.2 μs repetition period pulse as shown in the waveform example of FIG. .

Also, a CCD scan start signal for each scan
The inspection section signal 36out synchronized with 25 is input to the NOR circuit 46, and the inspection section signal 36out is inverted to output a signal 46out. As in the case of generating the inspection section signal 36out,
As the counter 47, a 4-digit BCD code output counter was used.

The counter 47 counts the drive pulse 24 for processing the linear array CCD signal when the inverted signal 46out of the inspection section signal 36out is low, and resets the count when it is high.

The dark part defect detection signal 11a output from the dark part signal detector 40 as shown in the waveform example of FIG. 9 is input to the NOR circuit 48, and the dark part defect detection signal output from the NOR circuit 48 is output. The inverted signal 48out of 11a is input to the data latch circuit 49.

In the data latch circuit 49, when the inverted signal 48out of the dark part defect detection signal 11a is in the low state, the counter 47
And outputs the count data 11b to the inspection management personal computer 12. As described above, the dark part defect detection signal 11a shown in FIG.
Since the status state is maintained for about a second, the held count data 11b can be sufficiently captured by the inspection management personal computer 12.

Next, the structure of the film sheet traveling direction defect position detecting section 50 will be described with reference to FIGS. Figure
FIG. 12 is a configuration diagram of the film sheet traveling direction defect position detecting section 50, and FIG. 13 shows an example of a signal waveform of each section of the film sheet traveling direction defect position detecting section 50.

The position detecting unit 50 detects a defect in the traveling direction of the film sheet.
Is constituted by using a K3TR type pulse counter manufactured by OMRON Corporation, and a length measuring pulse transmitter output signal 14 which is a repetition period pulse of 1 ms / pulse as shown in a waveform example of FIG. 13 is input to the pulse counter. As the length measuring pulse transmitter 13, a transmitter PR721 and a converter CR1310A manufactured by Ono Sokki Co., Ltd. were used. Inspection start / stop management is performed by the inspection management personal computer 12, and the inspection start / stop mode signal 51 is transmitted from the inspection management personal computer 12 to a contact signal from the film sheet traveling direction defect position detecting unit.
Input to 50 pulse counter.

This pulse counter has a count value of 10
The meter unit data 11c is output as 5-digit BCD code data and input to the inspection management personal computer 12. As described above, the dark part defect detection signal 11a output from the dark part signal detection unit 40 is input to the inspection management personal computer 12, and the dark part defect detection signal 11a is output to the inspection management personal computer.
The length measurement data at the time when the data is input to 12 can be known by the inspection management personal computer 12.

Since the film sheet 3 travels at 4 m / min and moves only 33 mm when the dark part defect detection signal 11a is ON for 0.5 second, the meter unit data 11c can be reliably read by the inspection management personal computer 12. .

Next, the configuration of the video signal level automatic adjusting section 52 will be described with reference to FIGS. FIG. 14 is a configuration diagram of the video signal level automatic adjustment unit 52, and FIG. 15 shows an example of a signal waveform of each unit of the video signal level automatic adjustment unit 52.
The video signal level automatic adjustment section 52 keeps the video signal level constant so that each section of the detection circuit 10 operates normally when the thickness of the film sheet 3 to be inspected is changed or when the luminance of the halogen lamp 15 decreases. Prepared for control. Therefore, the control performance is set to a long range of 1 second or more in terms of time.

The video signal level automatic adjusting section 52 is provided with an input stage amplifier 53 for inputting and receiving the camera output video signal 22 as shown in the waveform example of FIG. Camera output video signal
22 is input at about 1 V as an average value. The portion where the voltage is higher than the average value is a bright point, and the portion where the voltage is lower than the average value is a dark point. The camera output video signal 22 is a change signal having a high-speed cycle of 2 ms as described above.

The input stage amplifier 53 performs input overvoltage protection, gain adjustment, and zero point adjustment, and transmits a signal to the low frequency pass filter amplifier 54 of the next stage. The low frequency pass filter amplifier 54 has a time constant of about one second, that is, about one frequency.
It was designed to function as a very low frequency pass filter of about Hz.

Therefore, the camera output video signal 22 input to the video signal level automatic adjustment section 52 is 2 ms as described above.
However, the output 54out of the low frequency pass filter amplifier 54 is a signal of a slow following change in seconds as shown in the waveform example of FIG.

Further, the video signal level automatic adjusting section 52 has a CCD scanning start signal 25 which is a repetition pulse of 2 ms as shown in the waveform example of FIG.
The signal processing drive pulse 24 is input, and the input is received by the sampling hold timing pulse generation circuit 56. This sampling hold timing pulse generating circuit 56
A timing pulse 56out for sampling and holding the output 54out of the low frequency pass filter amplifier 54 is generated at an intermediate position of each cycle of the D-scan start signal 25.

The sampling hold timing pulse generating circuit 56 and the delay counter circuit have a required pulse width such that the timing pulse 56out is located at an intermediate position of each cycle of the CCD scanning start signal 25 as shown in the waveform example of FIG. It consists of a counter circuit and a pulse generation circuit. In this embodiment, the delay time is 250 μs and the pulse width is 60 μs. Note that the sampling hold timing pulse generation circuit 56 may have the same circuit configuration as the above-described inspection section setting unit 31.

The timing pulse 56out and the output 54out of the low frequency pass filter amplifier 54 are input to the sampling and holding circuit 55, and a sampling voltage 55out shown in the waveform example of FIG. 15 is obtained. On the other hand, a control reference setting voltage generating circuit 58 is prepared, and the control reference setting voltage 58out composed of a DC stationary voltage generated by the control reference setting voltage generating circuit 58 and shown in the waveform example of FIG. 15 is compared with the sampling voltage 55out. A comparison circuit 57 is prepared.

In the comparison circuit 57, {sampling voltage 55out}
Level <control reference setting voltage 58out level｝
In the case of, make use of the next-stage brightening amplifier section 59, the level of the sampling voltage 55out> the control reference setting voltage 58out
In the case of level｝, the adder 61 makes use of the next-stage light-attenuating amplifier unit 60 to combine them into one control output signal 18.

Halogen lamp supply power supplied to the halogen lamp 15 via the light source controller 4 by the control output signal 18 output from the video signal level automatic adjustment section 52
Adjust the light intensity 20 by adjusting 19, the camera output video signal 22
Can be automatically adjusted to about 1 V according to the purpose.

In this embodiment, the control output signal 18, which is the output of the video signal level automatic adjusting section 52, is DC 0
The halogen lamp supply power 19 was set to 0 to 12V. Also, the level of the camera output video signal 22 is about 1 V
, The output 54out of the low frequency pass filter amplifier 54
Since the level is lowered by the filter characteristic, the level of comparison with the control reference set voltage 58out in the comparison circuit 57 is 1 V or less. As described above, the control reference setting voltage 58out is optimally set so that the level of the camera output video signal 22 becomes about 1 V by utilizing the control function of the video signal level automatic adjusting section 52.

Next, a comparison example of the polarization directions of the first and second polarizers 8 and 9 corresponding to the characteristics of various defects, the camera output video signal 22 of various defects, and the video signal after shading correction is shown in FIG. a) to (d) and FIGS. 17 (a) and (b),
This will be described with reference to FIGS. 18 (a) and (b) and FIGS. 19 (a) and (b).

FIG. 16A shows the form of a bubble defect 62 generated inside the film sheet 3. There is a large distortion 63 around the bubble defect 62. FIG. 16B shows the form of a foreign matter defect 64 generated inside the film sheet 3. A large distortion 65 is present around the foreign matter defect 64.

FIG. 16C shows the form of the pinhole defect 66 generated in the film sheet 3. There is a large distortion 67 around the pinhole defect 66. FIG. 16D shows a form of a small distortion 68 generated inside the film sheet 3. Generally, it is preferable not to detect the small distortion 68 as a defect because it does not cause a problem in quality.

FIG. 17A shows the configuration of the above-described embodiment, in which the deviation angle θ between the polarization directions of the first polarizing plate 8 and the second polarizing plate 9 is shown.
17A shows a camera output video signal 22 output from the linear array camera 7 when the angle is set to substantially a right angle. FIG. 17B shows the camera output video signal 22 shown in FIG. The video signal after is shown.

FIG. 18A shows the configuration of the above-mentioned embodiment, in which the deviation angle θ between the polarization directions of the first polarizing plate 8 and the second polarizing plate 9 is shown.
FIG. 18 shows a camera output video signal 22 output from the linear array camera 7 when is set to about ± 50 degrees.
18B shows a video signal after shading correction of the camera output video signal 22 of FIG.

FIG. 19A shows the configuration of the above-described embodiment, in which the deviation angle θ between the polarization directions of the first polarizing plate 8 and the second polarizing plate 9 is shown.
FIG. 19 shows a camera output video signal 22 output from the linear array camera 7 when is set to about ± 20 degrees.
(B) shows a video signal after shading correction of the camera output video signal 22 of FIG.

First, a diagram showing a waveform example of the camera output video signal 22 output from the linear array camera 7 when the deviation angle θ between the polarization directions of the first polarizing plate 8 and the second polarizing plate 9 is substantially a right angle. 17 (a), the bubble defect 62
And a case having a small distortion 68 will be described.

Since the bubble defect 62 has a large internal distortion and a peripheral distortion, the linearly polarized light by the first polarizing plate 8 is rotated by the distortion to polarize the light in the right-angle direction.
The polarization direction component of the polarizing plate 9 increases and passes, and the linear array camera 7 catches it as a bright luminescent spot.

The above-described effect becomes apparent even with a small distortion 68 in the film sheet 3, and an image shines as a bright luminescent spot. Figure
In FIG. 17A, reference numeral 69a denotes a video signal of a portion corresponding to the bubble defect 62, and reference numeral 70a denotes a video signal of a portion corresponding to a small distortion 68 in the film sheet 3. Here, both the video signals 69a and 70a similarly shine as bright points, and the voltage of the camera output video signal 22 becomes a value close to the output saturation level of the linear array camera 7 of 5V.

When the defect detection threshold value TH1 is set to 4 V from the camera output video signal 22 to try to discriminate it from formation noise, both are detected. If the degree of the small distortion 68 is considered to be good in quality, the video signal 70a corresponding to this is used.
Is over-detected due to the detection of Also, the formation level fluctuates greatly due to the uneven molecular orientation and the uneven thickness of the film sheet 3, and as shown by the video signal 71a in FIG. 17A, it may reach the defect detection threshold value TH1 of 4V. Overdetection increases.

If the defect detection threshold value TH1 is set to a value of 4 V or more, for example, 4.5 V, over-detection of the formation level fluctuation can be avoided, but a small one such as the bubble defect 62 is 4.5.
In some cases, only a bright spot peak value equal to or lower than V is obtained, and in other cases, the peak value does not reach the defect detection threshold value TH1 and detection is not performed.

It is assumed that the shading correction section 26 having the above configuration is used.
17B, the result is as shown in FIG. 17B, and a brightness expression centering on 1V is obtained. In this case, if the defect detection threshold value TH2 is set to 2 V and it is attempted to discriminate it from formation noise,
The correction video signal 69b corresponding to the video signal 69a corresponding to the portion corresponding to the bubble defect 62 exceeds 5 V, so that the detection can be reliably performed. However, the correction video signal 70b corresponding to the video signal 70a corresponding to the portion corresponding to the small distortion 68 is also It is unavoidable that the voltage greatly exceeds 2 V and becomes the same level as the corrected video signal 69b corresponding to the bubble defect 62, resulting in overdetection.

In FIGS. 17A and 17B, the bubble defect 62
The small distortion 68 was taken as an example, but as for the foreign matter defect 64 and the pinhole defect 66, these defects also have large distortions 65 and 67 around them, as in the case of the bubble defect 62 described above. Then, an image which shines as a luminescent spot due to the distorted portion around the image becomes.

Further, since the foreign substance itself of the foreign substance defect 64 has a property of shielding light, it shows a signal of a dark part signal tendency of a dimming characteristic,
Since the pinhole portion itself of the pinhole defect 66 does not change the direction of linear polarization by the first polarizing plate 8, it is perpendicular to the direction of polarization of the second polarizing plate 9, and no light passes therethrough. It will show a trend signal.

Next, the camera output video signal 22 output from the linear array camera 7 when the deviation angle θ of the polarization direction between the first polarizing plate 8 and the second polarizing plate 9 is set to about ± 50 degrees. The case where the film sheet 3 has the foreign matter defect 64 and the pinhole defect 66 will be described with reference to FIG.

The video signal representing the foreign substance itself of the foreign substance defect 64 shows a signal of the dark part signal tendency of the dimming characteristic because the foreign substance itself has a light shielding property as shown at 72a in FIG. Also, the pinhole portion itself of the pinhole defect 66 is the first
In order not to change the linear polarization direction by the polarizing plate 8 of
When the polarization direction of the second polarizer 9 is at a right angle to the polarization direction of the first polarizer 8, a signal having a dark part signal tendency is shown as described above. When the angle difference is ± 50 degrees, the amount of light passing through the second polarizer 9 increases, so that the dimming characteristic is weakened, and the magnitude of the video signal becomes approximately equal to the formation noise as shown in 73a. .

It is assumed that the shading correction unit 26 having the above configuration is used.
18B, the brightness is expressed around 1V as shown in FIG. 18 (b), and the formation noise is about ± 0.2V around 1V. The corrected video signal of the foreign matter itself of the foreign matter defect 64 is a dark part signal of about 0.8 V as shown at 72b, and the corrected video signal of the pinhole part itself of the pinhole defect 66 is about 0.9V as shown at 73b. These are buried within the lower limit 0.8V of formation noise.

Further, a large defect 63 around the bubble defect 62 and the surroundings 63 in the film sheet 3 and a large distortion 63 around the foreign matter defect 64
65, with respect to a large distortion 67 around the pinhole defect 66, the deviation angle θ of the polarization direction between the first polarizing plate 8 and the second polarizing plate 9 gradually deviates from a right angle and approaches a parallel side. ±
It was found that when the angle reached about 50 degrees, almost no bright spot was expressed.

Next, the camera output video signal 22 output from the linear array camera 7 when the deviation angle θ of the polarization direction between the first polarizing plate 8 and the second polarizing plate 9 is set to about ± 20 degrees. The case where the film sheet 3 has the bubble defect 62 will be described with reference to FIG.

As the deviation angle θ in the polarization direction between the first polarizing plate 8 and the second polarizing plate 9 gradually approaches parallel from a right angle, the bubble defect 62 in the film sheet 3 and the large distortion 63 around the film defect 3 It was found that a bright luminescent spot as described above weakened, and when the deviation angle θ of the polarization direction became about ± 50 degrees, almost no bright spot was expressed.

Further, the deviation angle θ of the polarization direction is about ± 2.
It has been found that when the angle is about 0 degrees, as shown in the video signal 74a in FIG. With respect to the small distortion 68 in the film sheet 3, when the deviation angle θ in the polarization direction becomes about ± 50 degrees as described above, it is no longer buried in formation noise, and the deviation angle θ in the polarization direction becomes about ± 20 degrees. The same mode was obtained even when the degree reached.

Therefore, the deviation angle θ of the polarization direction is about ± 20.
When the temperature is reduced to a degree, the dark spot imaging of the bubble defect 62 in the film sheet 3 and the large distortion 63 around the film becomes apparent, and the small distortion 68 in the film sheet 3 separately scattered is no longer buried in formation noise. It turned out to be.

Then, the shading correction unit having the above configuration
When processing is performed using 26, the result is as shown in FIG.
In this case, if the defect detection threshold value TH3 is set to 0.7 V to discriminate from the formation noise, as shown in the corrected video signal 74b representing the bubble defect 62 and the large distortion 63 around it, the defect detection threshold TH3 is set to about 0.5 V or less. It becomes a dark area signal and can be reliably captured.

In this case, the separately scattered film sheet 3
Fig. 19 because the 68 small distortions inside are not visualized
As shown in (b), the noise is buried within the lower limit of 0.9 V of formation noise and is not excessively detected.

Furthermore, regarding the foreign matter defect 64, when the deviation angle θ of the polarization direction of the first and second polarizing plates 8 and 9 becomes about ± 20 degrees, the foreign matter defect 64 and a large distortion around it are generated. Since the image 65 is imaged as a dark dark portion signal, this portion can be captured by the defect detection threshold TH3 using the image after the shading correction processing by the shading correction unit 26.

On the other hand, regarding the pinhole defect 66,
When the deviation angle θ in the polarization direction becomes about ± 20 degrees from the above about ± 50 degrees, the amount of light passing through the second polarizing plate 9 by the pinhole portion itself of the pinhole defect 66 further increases. The pinhole portion itself larger than the resolution of the linear array camera 7 shines as a bright spot.

As described above, when the deviation angle θ between the polarization directions of the first and second polarizers 8 and 9 becomes about ± 20 degrees, the pinhole defect 66 also becomes large around the pinhole defect 66. Because the distortion 67 is visualized as a dark dark signal,
Using the image after the shading correction processing by the shading correction section 26, the dark portion signal portion can be captured by the defect detection threshold value TH3.

The pinhole defect 66 can be detected by capturing the bright signal of the pinhole defect 66. However, the capability of the pinhole defect 66 having a smaller diameter than the resolution of the linear array camera 7 is limited. Occurs. From the experimental results, it is clear that the pinhole defect 66 having a diameter smaller than the resolution of the linear array camera 7 also has a large distortion 67 around the pinhole defect 66 which is higher than the resolution of the linear array camera 7. Was.

On the other hand, as described above, the pinhole defect 66
If the configuration is such that a dark portion signal corresponding to a large distortion 67 around the pinhole defect 66 is smaller than the resolution of the linear array camera 7 even if the diameter of the pinhole defect itself is smaller than the resolution of the linear array camera 7, By capturing the large distortion 67, the pinhole defect 66 can be easily captured.

Further, when the deviation angle θ of the polarization direction between the first polarizing plate 8 and the second polarizing plate 9 changes from about ± 20 degrees to 0 degree (the polarization directions are parallel to each other), the film Large distortion around the various defects generated in the sheet 3 63,6
It has been found that the dark signal for the pixels 5 and 67 is further increased, and the small distortion 68 separately scattered in the film sheet 3 is hardly increased.

Therefore, the first polarizing plate 8 and the second polarizing plate 9
It has been found that setting the deviation angle θ of the polarization direction between 0 ° and 0 ° more than about ± 20 ° improves the S / N ratio between the defect signal and the formation noise.

Therefore, the practical usable range is as follows:
Although the deviation angle θ between the polarization directions of the first polarizing plate 8 and the second polarizing plate 9 may be about ± 20 degrees, in the above-described embodiment, the first polarizing plate 8 and the second polarizing plate 9 Is set to 0 degree (the polarization directions are parallel to each other).

According to the above configuration, the shading correction section
26 corrects the waveform distortion of the camera output video signal 22 due to the change in the partial orientation unevenness of the inspection target film sheet 3 and the aberration caused by the aperture setting of the lens 21 for the linear array camera 7, and makes the camera output video signal 22 uniform. By using a flat level, defects can be uniformly detected in any part of the inspection range.

For example, the lens 21 for the linear array camera 7
Speaking of the example of the aperture, when the aperture is greatly opened to 2.8 ゃ 1.4, the start side and the end of the camera output video signal 22 are changed like the waveform example of the camera output video signal 22 shown in FIG. The decrease in the level on the side increases. If the repetition rate of the scanning start signal of the linear array camera 7 is increased in order to increase the traveling speed of the film sheet 3 and keep the resolution in the traveling direction small, the sensitivity of the camera output video signal 22 decreases, and the lens 21 When the aperture of the camera is wide open, the edge drop phenomenon is observed in the camera output video signal 22 as described above.

Not only the partial orientation unevenness of the film sheet 3 but also the thickness unevenness of the film sheet 3 causes irregularities to appear at portions of the camera output video signal 22 corresponding to the above-mentioned uneven alignment and uneven thickness. In such a case, the shading correction unit 26 can flatten the camera output video signal 22 and can set the threshold value for defect extraction to a constant voltage, which is very effective.

Regarding the enlargement of the width of the film sheet 3 to be inspected, the linear array camera 7, the second polarizer 9,
A plurality of detection circuits 10 and the like will be provided. For example, if the detection circuit 10 is applied to a film sheet 3 having a width of 2 m,
In order to keep the resolution in the running direction small as the running speed of the film sheet 3 increases, a linear array camera 7 having 5000 bits and a video signal video rate of 20 MHz should be employed. Good.

In the above embodiment, the shading correction section
Although shading correction by subtraction is used as 26, division shading correction in which a subtraction unit is replaced by a division unit may be used, and in this case, performance is further improved.

In the above embodiment, the case where an aramid film is applied as the film sheet 3 to be inspected has been described. However, defect inspection of transparent and translucent films such as other polyester films, polypropylene films, polystyrene films, and polyimide films. Available to

[0133]

According to the present invention, since it has the above-described configuration and operation, the following excellent effects can be exhibited.

(1) A pair of polarizing plates is placed on both sides of a film sheet to be inspected, and the deviation angle of the polarizing direction between the first polarizing plate on the light source side and the second polarizing plate on the linear array camera side is determined. By setting the angle to 0 degree or at least within ± 20 degrees, for a bubble defect or a foreign matter defect, a large distortion portion around each defect portion and the surrounding portion is manifested as a dark portion signal, and a large distortion portion around a pinhole defect is revealed. Various defects can be reliably detected by making them appear as dark portion signals.

(2) The shading correction unit corrects the video signal waveform distortion caused by the variation in the partial orientation unevenness of the film sheet to be inspected or the aberration caused by the aperture setting of the lens for the linear array camera, and makes the video signal a uniform flat level. By doing so, a defect can be uniformly detected in any part of the inspection range.

(3) The width direction defect position can be known in millimeter units by the film sheet width direction defect position detection unit. This is almost impossible with the above-described conventional discharge-type pinhole inspection machine.

(4) The defect position detection unit in the film sheet traveling direction can know the defect position in the film sheet traveling direction by the film sheet traveling direction defect position detection unit. Can be provided. Therefore, when slitting a film sheet in a post-process, it is possible to know in advance whether or not a defect is included in the slit product, and it is possible to avoid shipping a product having a defective portion, and to assure quality. In addition, manufacturing costs can be reduced.

(5) The video signal automatic level adjustment unit keeps the average level of the video signal constant in response to a change in the thickness of the inspection target film sheet or a decrease in the luminance of the light source such as a halogen lamp. It is possible to reliably detect defects.

(6) By using a line-type halogen light source as a light source, it is possible to secure a light amount ten times or more as compared with the fluorescent lamp illumination. If the repetition rate of the scanning start signal of the linear array camera is increased in order to keep the resolution of the running direction small and the running speed of the film sheet increased, the video signal sensitivity decreases The signal has an edge drop phenomenon. In such a case, if the line-type halogen light source is used, it is not necessary to open the lens aperture greatly, and the phenomenon of lowering the edge of the video signal can be avoided.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a film sheet defect inspection apparatus according to the present invention.

FIG. 2 is a diagram showing a linear array camera and its signal configuration.

FIG. 3 is a block diagram illustrating a configuration of a detection circuit.

FIG. 4 is a block diagram illustrating a configuration of a shading correction unit.

FIG. 5 is a diagram illustrating a signal waveform of each unit of a shading correction unit.

FIG. 6 is a block diagram illustrating a configuration of an inspection section setting unit.

FIG. 7 is a diagram showing a signal waveform of each unit of an inspection section setting unit.

FIG. 8 is a block diagram illustrating a configuration of a dark part signal detection unit.

FIG. 9 is a diagram illustrating signal waveforms at various parts of a dark part signal detection unit.

FIG. 10 is a block diagram illustrating a configuration of a film sheet width direction defect position detection unit.

FIG. 11 is a diagram showing signal waveforms at various parts of a film sheet width direction defect position detection unit.

FIG. 12 is a block diagram illustrating a configuration of a film sheet traveling direction defect position detection unit.

FIG. 13 is a diagram showing signal waveforms at various parts of a film sheet traveling direction defect position detection unit.

FIG. 14 is a block diagram illustrating a configuration of a video signal level automatic adjustment unit.

FIG. 15 is a diagram illustrating a signal waveform of each unit of the video signal level automatic adjustment unit.

16A is a diagram illustrating a state of a bubble defect generated inside the film sheet, FIG. 16B is a diagram illustrating a state of a foreign matter defect generated inside the film sheet, and FIG. 16C is a pin illustrating a pin generated in the film sheet. FIG. 3D is a diagram showing a state of a hole defect, and FIG. 4D is a diagram showing a state of a small distortion portion generated inside the film sheet.

17A is a diagram illustrating a video signal waveform output from a linear array camera when the polarization direction shift angle θ between the first polarizing plate and the second polarizing plate is substantially a right angle, and FIG. FIG. 3A is a diagram showing a video signal waveform after shading correction of the video signal of FIG.

FIG. 18A is a diagram illustrating a video signal waveform output from a linear array camera when a deviation angle θ of a polarization direction between a first polarizing plate and a second polarizing plate is about ± 50 degrees; FIG. 2B is a diagram showing a video signal waveform after shading correction of the video signal of FIG.

FIG. 19A is a diagram illustrating a video signal waveform output from a linear array camera when a deviation angle θ of a polarization direction between a first polarizing plate and a second polarizing plate is approximately ± 20 degrees. FIG. 2B is a diagram showing a video signal waveform after shading correction of the video signal of FIG.

[Explanation of symbols]

1, 2, roll, 3 film sheet, 4 light source controller, 5 line type light source, 6 linear array camera controller, 7 linear array camera, 8, 9 first
Second polarizing plate, 10 detection circuit, 11 defect detection information, 11a
… Dark part defect detection signal, 11b… Count data, 11c… Meter unit data, 12… Inspection management personal computer, 13… Measuring pulse transmitter, 14… Measuring pulse transmitter output signal, 15… Halogen lamp, 16… Quartz Adapter, 17… Cylindrical quartz rod, 18… Control output signal, 19… Halogen lamp power supply,
20: Light intensity, 21: Lens, 22: Camera output video signal, 23
... DC power supply, 24 ... Drive pulse for linear array CCD signal processing, 25 ... CCD scanning start signal, 26 ... Shading correction unit, 27 ... Input stage amplifier, 28 ... Low frequency pass filter amplifier, 29 ... Addition circuit, 29a-29c ... short pulse, 30 ... output stage amplifier, 30a-30c ... short pulse, 31 ... test section setting part, 32 ... retrigger single shot multivibrator, 33 ... counter, 34 ... digital comparator, 35 ...
Digital switch, 36… Single shot multivibrator, 36out… Test section signal, 37… Counter, 38…
Digital comparator, 39 ... Digital switch, 40 ... Dark part signal detector, 41 ... Comparator, 41a, 41c ... Short pulse, 42
... comparative voltage generating circuit, 43 ... AND circuit, 43a ... short pulse, 44 ... single shot multivibrator, 45 ... film sheet width direction defect position detecting section, 46 ... NOR circuit,
47 ... Counter, 48 ... NOR circuit, 49 ... Data latch circuit, 50 ... Film sheet running direction defect position detection unit, 51 ...
Inspection start / stop mode signal, 52: Video signal level automatic adjustment unit, 53: Input stage amplifier, 54: Low frequency pass filter amplifier, 55: Sampling and holding circuit, 55out ...
Sampling voltage, 56 ... Sampling hold timing pulse generation circuit, 56out ... Timing pulse, 57 ... Comparison circuit, 58 ... Control reference setting voltage generation circuit, 58ou
t: Control reference setting voltage, 59: Brightening amplifier, 60
... Dimming amplifier, 61 ... Addition circuit, 62 ... Bubble defect, 63 ... Large distortion, 64 ... Foreign defect, 65 ... Large distortion, 66 ... Pin hole defect, 67 ... Large distortion, 68 ... Small distortion, 69a, 70
a, 71a, 72a, 73a, 74a ... video signal, 69b, 70
b, 72b, 73b, 74b... corrected video signal, TH1, TH2,
TH3: Defect detection threshold, θ: Deviation angle

Claims (7)

[Claims] 1. A light source is arranged on one surface side of a film sheet conveyed by a film sheet conveying means, a linear array camera is arranged on the other surface side of the film sheet, and output from the linear array camera. In a film sheet defect inspection method for detecting defect information from a video signal, a first polarizing plate disposed between the film sheet and the light source, and disposed between the film sheet and the linear array camera A film sheet defect inspection, wherein a deviation angle of a polarization direction with respect to a second polarizing plate is set within ± 20 degrees, and a dark portion signal extracted from a video signal output from the linear array camera is detected as a defect. Method. 2. A light source is arranged on one surface side of a film sheet conveyed by a film sheet conveying means, and a linear array camera is arranged on the other surface side of the film sheet, and output from the linear array camera. In a film sheet defect inspection device for detecting defect information from a video signal, a first polarizing plate disposed between the film sheet and the light source, and disposed between the film sheet and the linear array camera A second polarizing plate having a deviation angle of the polarization direction with respect to the first polarizing plate within ± 20 degrees, and a dark portion signal extracted from a video signal output from the linear array camera to obtain the dark portion. A detection circuit including a dark part signal detection unit that detects a signal as a defect. 3. The film sheet defect inspection apparatus according to claim 2, wherein the detection circuit has a shading correction section at a stage preceding the dark section signal detection section. 4. A film sheet for detecting a defect position in the film sheet width direction using an output signal of the dark area signal detection section, a drive pulse signal for driving the linear array camera, and a scan start signal. The film sheet defect inspection apparatus according to claim 2, further comprising a width direction defect position detection unit. 5. A film sheet transporting means provided with a length measuring pulse transmitter, wherein said detecting circuit uses a signal output from said dark part signal detector and an output signal from said length measuring pulse transmitter to travel in a film sheet traveling direction. The film sheet defect inspection device according to any one of claims 2 to 4, further comprising a film sheet traveling direction defect position detection unit that detects the defect position of (1). 6. The film sheet defect inspection apparatus according to claim 2, wherein the detection circuit has a video signal level automatic adjustment unit. 7. The film sheet defect inspection apparatus according to claim 2, wherein a line type halogen light source is used as the light source.