JPH0915169A - Inspecting equipment of transparent sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable high-speed inspection of an indented defect on the opposite sides of a transparent sheetlike substance to be inspected and an internal abnormality thereof by a method wherein an image of a chart provided with a regular pattern is picked up through the substance to be inspected. SOLUTION: A multi-line chart 1a constructed by arranging at least two kinds of openings (patterns) having a prescribed width and different transmittances alternately and laterally on one plane is illuminated by a radiant light flux of a light source 1b being diffused and a sheetlike substance 2 to be inspected such as a transparent film, for instance, is disposed parallel to the surface of the chart 1a at a prescribed distance therefrom. The substance 2 to be inspected is moved in the longitudinal direction (the direction of an arrow) of the slit-shaped openings and an image of the chart 1a is picked up through the substance 2 and formed on a sensor array 4b of a line sensor 4 by an image pickup lens 3. A photoelectric conversion signal 4a of a part whereon the image is formed is binary-coded by a binarization processing circuit 5 and a pulse time and the period thereof are measured by a pulse measuring circuit 6. When either the pulse time or the period deviates from a standard value set in a controller 8, an acceptance/reject determining circuit 7 determines this as abnormality and outputs a signal 7a .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent sheet inspection apparatus, and is particularly suitable for inspecting transparent sheets such as transparent films and transparent glass plates.

[0002]

2. Description of the Related Art Conventionally, as a device for inspecting irregularities on the surface, there is a transparent sheet inspection device shown in FIG. In this transparent sheet inspection apparatus, the surface 12 of the inspection object is irradiated with light from the illumination unit 11 having the multi-line chart 11a. if,
If the surface of the inspection object has an uneven shape, the disorder 12a of the multi-line chart image appears. This is a multi-line chart image 11b
On the other hand, the television camera 1 in which the horizontal scanning direction is arranged in parallel
3, the image signal is processed, the disorder 12a is detected, and the pass / fail judgment is performed.

[0003]

When inspecting a transparent sheet such as a transparent film or a transparent glass plate, it is required to inspect irregularities on two surfaces of both sides of the sheet, and further inspect an abnormality inside the sheet. Has been done.

However, if an attempt is made to inspect a transparent sheet by the above-mentioned conventional transparent sheet inspection apparatus, it is necessary to inspect each sheet one by one, and the inspection requires twice as much time and the inspection time becomes long. Further, the above-mentioned conventional transparent sheet inspection device cannot inspect any abnormality inside the transparent sheet.

An object of the present invention is to provide a transparent sheet inspection device capable of inspecting both sides of a transparent sheet-shaped inspection object at high speed. Furthermore, it aims at providing the apparatus which can also inspect the inside of a sheet | seat.

[0006]

The transparent sheet inspection apparatus of the present invention is (1-1) an apparatus for inspecting a transparent sheet-like inspection object, which is a chart having a regular pattern, and the chart. It is characterized in that it has an image pickup means for picking up an image through the inspection object.

In particular, (1-1-1) the chart is one in which at least two patterns having different transmittances are alternately and repeatedly arranged. (1-1-2) Each of the at least two types of patterns has the same width in the pattern arrangement direction. (1-1-3) The inspection surface of the inspection object and the chart were arranged in parallel. (1-1-4) A moving unit that moves the inspection object relative to the imaging unit is provided. (1-1-5) The image pickup means includes a one-dimensional photoelectric conversion element array. (1-1-6) It has a means for inspecting an object to be inspected by binarizing the output of the image pickup means. (1-1-7) of the pulse signal obtained by the binarization,
The inspection object is inspected based on the pulse time and the pulse period. (1-1-8) If at least one of the pulse time and the pulse period deviates from a specified value, it is determined that the transparent sheet has an abnormality. (1-1-9) A light-shielding unit that shields an optical path from the inspection portion of the inspection object to the imaging unit is provided. It is characterized by

[0008]

FIG. 1 is a schematic view of a main part of a first embodiment of the present invention. In the figure, 1b is a light source, which is composed of a fluorescent lamp which is turned on at a high frequency. 1c is a milky white translucent diffusion plate. 1
Reference numeral a is a multi-line chart (chart), which is configured by arranging a plurality of two linear slit-shaped openings (patterns) having different transmittances alternately in a one-dimensional direction on one plane. The multi-line chart 1a of this embodiment has an opaque opening (pattern) of width w.
And transparent openings (patterns) of width w are alternately arranged side by side (in the one-dimensional direction), and have a width that covers the width W of the inspection object 2. Since the width w affects the detection resolution, w = 2 mm or less is taken into consideration in this embodiment in consideration of the area where irregular surface defects and internal abnormalities occur.

The light beam emitted from the light source 1b becomes diffused light on the diffusion plate 1c and illuminates the multi-line chart 1a. Since the multi-line chart 1a of the present embodiment is formed by a transparent opening and an opaque opening, the multi-line chart 1a has a very high contrast. In addition, the light source 1b, the diffusion plate 1c,
Etc. constitute one element of the illumination means 1.

The inspection object 2 is, for example, a transparent film,
They are arranged parallel to the surface of the multi-line chart 1a with a certain distance, and in the inspection, the direction of the arrow, that is, the multi-line chart 1
It moves parallel to the longitudinal direction of the slit-shaped opening forming a. Reference numerals 9a and 9b denote support rotary rollers for supporting the inspection object 2, which keeps the inspection portion flat and is rotatable and sends the inspection object 2 without scratching the surface. The support rotation roller 9b rotates to move the inspection object 2. 10 is a rotary encoder, which is one of the supporting rotary rollers 9
The rotation amount of the support rotation roller 9b directly connected to b is measured. The support rotation rollers 9a, 9b and the like constitute one element of the moving means. In addition, the inspection object 2 is replaced with the multi-line chart 1
Since it is arranged parallel to a, the inspection object 2 is irradiated with a uniform irradiation light amount.

An image pickup lens 3 forms an image of the multi-line chart 1a through the inspection object 2. Reference numeral 4 denotes a one-dimensional photoelectric conversion element, which is composed of a one-dimensional CCD sensor (hereinafter abbreviated as a line sensor) and has a single sensor row 4b on which a multi-line chart 1a which forms an image is formed.
Image is converted into a photoelectric conversion signal. In addition, the sensor row 4b
Are arranged parallel to the surface of the multi-line chart 1a and in a direction orthogonal to the moving direction of the inspection object 2.
Further, 4b 'is a position corresponding to the sensor array in which the sensor array 4b is projected on the multi-line chart 1a by the imaging lens 3. The image pickup lens 3, the photoelectric conversion element 4, and the like form one element of the image pickup means.

Reference numeral 5 denotes a binarization processing circuit for binarizing the photoelectric conversion signal 4a from the line sensor 4, and 6 denotes a pulse time and an interval time (cycle) of the output signal 5a from the binarization processing circuit 5. Pulse measuring circuit, 7 is pulse measuring circuit 6
The output signal 6a from the standard value is compared with the standard value,
When the result is bad (when an abnormality is detected), the pass / fail judgment circuit outputs the signal 7a. Reference numeral 8 denotes a controller that controls the entire inspection apparatus.

The feed direction of the inspection object 2 is the sensor row 4b.
It is a direction that is perpendicular to the direction in which the lines are arranged, and is sent at a constant speed in this direction. The optical axis of the imaging lens 3 is perpendicular to the inspection object 2, the surface of the multi-line chart 1a, and the sensor array 4b.
The imaging lens 3 is focused on the multi-line chart 1a,
Therefore, the light flux from the multi-line chart 1a passes through the inspection object 2 and then forms an image on the sensor array 4b by the imaging lens 3.

Although not shown in this embodiment, the optical path from the inspection portion of the inspection object 2 to the sensor array 4b is covered with a light shielding cover. That is, the imaging lens 3, the line sensor 4, the inspection portion on the inspection object 2 and the periphery thereof are surrounded by a light-shielding plate whose inner surface is anti-reflection except for the opening of the inspection object 2 to shield external light. . As a result, the inspection object 2
Noise due to external light irradiation on the inspection part of the camera and the photographing lens 3
The influence of external light such as flare on the image pickup by external light is eliminated.

Next, the operation of this embodiment will be described. When an inspection start command is input to the controller 8, a feed drive start command 8c for the inspection object 2 is output, and the inspection object 2 starts moving in the arrow direction at a constant speed. Simultaneously with the start of feeding the inspection object 2, an image of the multi-line chart 1a is formed on the sensor array 4b through the inspection lens 2 through the imaging lens 3, and the portion of the formed image of the sensor array 4b is photoelectric. It is converted and output as a photoelectric conversion signal 4a.

It should be noted that the object 2 to be inspected depends on the reading time (T) of the line sensor 4 once and the feed speed (V) of the object 2 to be inspected.
The surface inspection pitch Pc in the feeding direction of is determined. The relationship is Pc
= V * T. In this embodiment, T = 2 (msec), V = 500
Since it is (mm / sec), the inspection pitch Pc is 1mm, which is 1mm
The image of the multi-line chart 1a is read through the surface of the inspected object 2 which is moving in units and photoelectrically converted, and the photoelectric conversion signal 4a is obtained.
To output continuously.

FIG. 2 (A) is a cross-sectional view of the object 2 to be inspected when the surface of the object to be inspected 2 has no shape change, and FIG. It is explanatory drawing of the image 2a of 1a. When the inspection object 2 is a non-defective product, there are no irregularities on the surface as shown in FIG. 2 (A), and there are no abnormalities (refractive index anomaly or bubbles) inside the inspection object. The refraction change of the light flux does not occur, and the image of the multi-line chart 1a is shown in FIG.
As shown in (B), a multi-line chart image is obtained which is regularly arranged at equal intervals.

FIG. 3 is an explanatory diagram of signals output at this time. The photoelectric conversion signal 4a _{1 in} FIG. 3A is an output signal from the line sensor 4 which photoelectrically converts the image on the sensor array 4b. The photoelectric conversion signal 4a ₁ from the line sensor 4 is a signal which is regularly repeated as shown.

The photoelectric conversion signal 4a ₁ from the line sensor 4 is input to the binarization processing circuit 5, is input as a signal 8a from the controller 8 in advance, and is compared with the set threshold voltage 5b to determine the threshold value. A voltage part larger than the value voltage 5b is converted to a high level, and a voltage part smaller than the threshold voltage 5b is converted to a low level, and a pulse signal is output as the output signal 5a ₁ . This output signal 5a ₁ is then input to the pulse measuring circuit 6, and each high-level pulse time (p ₁ , p ₂ , p ₃ ... P _n-1 , p _n ) of the output signal 5a ₁
And high-level pulse period (t ₁ , t ₂ , t ₃ ... t
_n−1 , t _n ) is measured, and the high level pulse time (p) and the high level pulse period (t) are input as the output 6a ₁ to the pass / fail judgment circuit 7 immediately after the time measurement of each cycle. . The time measurement in the pulse measuring circuit 6 is performed by using the reference clock, counting the number of clocks during the high pulse, and counting the number of clocks between the rising of the high pulse and the rising of the next high pulse.

In the pass / fail judgment circuit 7, the controller 8 previously sets the signal 8b as a standard value (standard time) to High.
The upper limit of the pulse time of the level (p _H) and lower limit value (p
_L ), and the upper limit value (t _H ) and the lower limit value (t _L ) of the pulse cycle of the High level are set, and the pulse time p and the pulse cycle t in the output 6a ₁ are compared with the above standard values, respectively. , Whether the high-level pulse time p is between the standard values p _{H and} p _L , and whether the high-level pulse period t is between the standard values t _{H and} t _L. Is within the standard value, the inspected portion of the inspection object 2 is a good product. If either one deviates from the standard value, it is determined that the inspected portion of the inspection object 2 is abnormal, and the short High pulse signal s is output to the controller 8 as the output 7a from the pass / fail judgment circuit 7.

In the case of the signal of FIG. 3, since the regular photoelectric conversion signal 4a ₁ is input to the binarization processing circuit 5,
In the output signal 5a ₁ from the binarization processing circuit 5, each Hi
gh level pulse time (p ₁ , p ₂ , p ₃ ... P _n-1 , p
_n ) has almost the same value, and the pulse periods (t ₁ , t ₂ , t ₃ ... t _n-1 , t _n ) of each High level also have substantially the same value. Therefore, in this case, there is no pulse that deviates from the standard value, so that it is determined that the inspection portion of the inspection object 2 has no defect, and no signal is output from the pass / fail determination circuit 7.

The inspection range information is previously input to the acceptance / rejection determination circuit 7 from the controller 8 as the signal 8b, and the above determination operation is performed only when the inspection range signal 7b in FIG. 3C is at the high level. Be seen. The inspection range signal 7b is an AND output signal of the time signal from the start to the end of the inspection and the inspection area signal in the width direction of the inspection object 2.

FIG. 4 (A) is an example of a cross-sectional view of the inspection object 2 when the inspection object 2 is a defective product having unevenness on the surface, and FIG. 4 (B).
Is a multi-line chart 1a which forms an image on the sensor array 4b at this time.
2B is an explanatory diagram of the image 2b of FIG. In this case, as shown in FIG. 4 (A), the cross section of the inspection object 2 has a bulge portion 2c. Therefore, when the multi-line chart 1a is imaged through the inspection object 2, as shown in FIG. 4 (B), a change in the thickness of the bulge portion 2c causes a refraction change in the light beam, and the multi-line chart 1a with regularity is generated. Is deformed to form an image.

FIG. 5A shows a photoelectric conversion signal 4a ₂ which photoelectrically converts the image on the sensor array 4b and outputs it to the binarization processing circuit 5 at this time, and 5a ₂ represents the photoelectric conversion signal 4a ₂ in binary. The digitization processing circuit 5 binarizes and outputs to the pulse measurement circuit 6 2
It is a pulsed signal that has been digitized. In the pulse measuring circuit 6, each high level pulse time (p ₁ , p ₂ , p ₃ , p ₄ , p ₅ , p ₆ , p ₇ ... Of the input pulse signal 5a ₂ ...
_pn−1 , _pn ) and the pulse period (t ₁ ,
t ₂ , t ₃ , t ₄ , t ₅ , t ₆ , t ₇ ... t _n-1 , t _n )
Is measured and the result is output to the pass / fail judgment circuit 7. In the pass / fail judgment circuit 7, the measurement time result of each pulse is compared with each standard value, and if the pulse is out of the standard, it is judged that the inspection portion is abnormal, and the output 7a ₂ is short Hi.
The gh pulse s is output to the controller 8. In the example of FIG. 5, short hi immediately after each determination of t ₂ , t ₃ , t ₄ , t ₅ , and t _6.
gh pulse (s ₂ , s ₃ , s ₄ , s ₅ , s ₆ ) output 7a
₂ is output to the controller 8.

At the same time, the controller 8 controls each high pulse s
_For each output of _i, the number of output pulses of the rotary encoder 10 directly connected to the support rotary roller 9b immediately after the start of the inspection is taken in as an output 8d _i , and the moving distance of the inspection object 2 immediately after the start of the inspection is calculated and temporarily Remember. Further, the position in the width direction of the inspection object 2 that outputs the high pulse s _i according to the time from the rise of the inspection range signal 7b in the width direction of the inspection object 2 to each short High pulse s _i output as the output 7a _2. Is calculated and temporarily stored. As a result, all the defective locations on the inspection object 2 are stored.

For example, the peripheral length a of the supporting rotary roller 9b is
a = 100 (mm), the number of output pulses R _P per rotation of the rotary encoder 10 is R _P = 1000 (pulses), and K is the distance from the supporting rotary roller 9b to the sensor row corresponding position 4b ′. When a short High pulse s ₂ is output to the output signal 7a ₂ , if the read value R _N of the output pulse of the rotary encoder 10 is R _N = 5000 (pulse), a high pulse s ₂ is output from the inspection start point. The feed distance NL _s2 of the object to be inspected 2 until the inspection is NL _s2 = (R _N / R _P ) * a + K = 50
It is calculated as 0 + K (mm), and the defect existing position in the feed direction of the inspection object 2 becomes clear. Controller 8 is this value
Remember NL _s2 .

The defective position in the width direction of the object to be inspected at that time is a value T _N (msec) obtained by adding the respective periods t ₁ , t ₂ and t ₃ of the high pulse from the rising time of the inspection range signal 7b in the width direction. ) and is determined from the rising of the examination region signal 7b and the width direction length W of the specimen 2 and the time T _W to fall. For example,
If T _N = 0.04 (msec) and T _W = 1 (msec),
Since this T _W time corresponds to the width W of the inspected object 2 = 200 (mm), the defective position NW _{s2 in} the width direction is NW _s2 = T _N * W / T _W = 8 (mm)
Is calculated, and the controller 8 determines the defective position NW _{s2 in the} width direction.
Is stored. As described above, the position in the feeding direction (NL _s2 ) and the position in the width direction (NW _s2 ) at that position are stored as the defective position on the surface of the inspection object.

In the present embodiment, it is determined that the signal is binarized when the high-level pulse time or the high-level period of the binarized signal deviates from the upper or lower standard time. Therefore, the defective portion can be reliably detected.

Further, since the multi-line chart composed of transparent and opaque openings at equal intervals is used as the chart and the one-dimensional CCD sensor is used as the image pickup means, the pass / fail judgment of the binarized signal is easy. Yes, the entire device is simple.

In the first embodiment, the object 2 to be inspected is sent continuously.
The image of the multi-line chart 1a is imaged on the one-dimensional sensor array 4b through the line, and the photoelectric conversion signals of the image formed are continuously processed, whereby the surface of the inspection object 2 is abnormal (unevenness). Defects) and abnormalities inside the object to be inspected (abnormal refractive index or bubbles),
That is, the characteristics (optical characteristics) of the object to be inspected can be inspected at the same time on both sides of the inspection pitch Pc, continuously and at high speed.

Further, in the first embodiment, since the outside light shielding cover is provided, the influence of the outside light is eliminated when the multi-line chart is imaged, and a noise-free multi-line chart image is taken for measurement. The accuracy is increasing.

The widths of the two slit-shaped openings forming the multi-line chart 1a may be different, because the multi-line chart may be formed by repeating two openings. Further, in the first embodiment, hi of the binarized pulse signal
An abnormality was detected by the time and cycle of the gh level.
It is also possible to detect anomalies by the time and cycle of w levels.

[0033]

The present invention achieves a transparent sheet inspection apparatus capable of inspecting both sides of a transparent sheet-like inspection object at high speed with the above-described structure. Furthermore, the inside of the inspection object can be inspected.

In addition to the above, according to the present invention, (3-1) By imaging the multi-line chart through the inspected object, uneven lines on the surface of the inspected object and abnormalities inside the inspected object are detected. An image is taken as a modification of the chart image, and a defect is determined by signal processing of the photoelectric conversion signal. Therefore, both sides and the inside of the inspection object can be inspected at the same time, and inspection can be performed efficiently and in a short time. (3-2) Since a multi-line chart having regularity in which two openings having the same opening width and different transmittances are alternately arranged is used as the multi-line chart, the determination process of the deformation of the multi-line chart image is simple. Therefore, the inspection result can be output in real time. (3-3) An object to be inspected can be imaged in one dimension in the width direction and photoelectrically converted by the one-dimensional sensor, and the object can be inspected while continuously feeding the object to be inspected, thereby speeding up the inspection. (3-4) Since the defect (abnormality) is determined when either the time or the cycle of the pulse signal obtained by binarizing the image of the multi-line chart deviates from the standard time, it is necessary to reliably detect the defective portion. You can (3-5) By providing a light-shielding cover for external light, it is possible to eliminate the influence of external light when capturing the multi-line chart and capture a multi-line chart image without noise. It is possible to achieve a transparent sheet inspection apparatus having at least one effect such as

[Brief description of the drawings]

FIG. 1 is a schematic view of a main part of a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of a non-defective part and an explanatory diagram of an image of a multi-line chart formed on the line sensor of Example 1.

FIG. 3 is an explanatory diagram of each output signal at the time of inspection of a non-defective part in the first embodiment.

FIG. 4 is an explanatory view of an example of a cross-sectional view of a defective part and an image of a multi-line chart formed on the line sensor of Example 1.

FIG. 5 is an explanatory diagram of each output signal when inspecting a defective part in the first embodiment.

FIG. 6 is a schematic view of a main part of a conventional transparent sheet inspection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Illumination section 1a Multi-line chart 1b Light source 1c Diffuser 2 Inspected object 3 Imaging lens 4 Line sensor 4b Sensor array 5 Binarization processing circuit 6 Pulse measurement circuit 7 Pass / fail judgment circuit 8 Controller 9a, 9b Supporting rotary roller 10 Rotary encoder

Claims (10)

[Claims] 1. An apparatus for inspecting a transparent sheet-shaped object to be inspected, comprising: a chart on which a regular pattern is arranged; and an imaging means for imaging the chart through the object to be inspected. Transparent sheet inspection device. 2. The transparent sheet inspection device according to claim 1, wherein the chart is a pattern in which at least two types of patterns having different transmittances are alternately and repeatedly arranged. 3. The transparent sheet inspection device according to claim 2, wherein each of the at least two types of patterns has the same width in the pattern arrangement direction. 4. The transparent sheet inspection apparatus according to claim 1, wherein an inspection surface of the inspection object and the chart are arranged in parallel. 5. The transparent sheet inspection apparatus according to claim 1, further comprising a moving unit that relatively moves the object to be inspected with respect to the image pickup unit. 6. The transparent sheet inspection apparatus according to claim 5, wherein the image pickup means includes a one-dimensional photoelectric conversion element array. 7. A means for inspecting an object to be inspected by binarizing an output of the image pickup means.
The transparent sheet inspection device according to any one of items 1 to 6. 8. The pulse signal obtained by the binarization,
The transparent sheet inspection apparatus according to claim 7, wherein the inspection object is inspected based on the pulse time and the pulse period. 9. The transparent sheet inspection apparatus according to claim 8, wherein when at least one of the pulse time and the pulse period deviates from a specified value, it is determined that the transparent sheet has an abnormality. 10. The transparent sheet inspection apparatus according to claim 1, further comprising a light shielding unit that shields an optical path from an inspection portion of the inspection object to the imaging unit.