JP2003315278A - Defect inspection device for film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately inspect a film drawn out of a molding machine for defect corresponding to the actual formation of the film by changing a threshold as the luminance level of the film changes and, at the same time, setting a changeable ceiling value. <P>SOLUTION: A defect inspection device for film is provide with a luminance detecting section 41 which detects the luminance level of the surface of the film from the image of the film picked up by means of a CCD line sensor 23; a judging section 42 which compares the detected luminance level with a threshold and, when the luminance level exceeds the threshold, judges that the film has a defect; and a threshold setting control unit 43 which successively sets and changes the threshold so that the threshold may become the sum of the mean value of the luminance levels of several proximate images after comparison and a fixed value. The inspection device is also provided with a storage section 44 prestoring the ceiling value of the threshold. The control unit 43 compares a set threshold with the ceiling value stored in the storage section 44 at any time and, when the set threshold exceeds the ceiling value, fixes the subsequent threshold to the ceiling value. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film defect inspection apparatus for inspecting sheet-shaped films that are successively taken out for defects.

[0002]

2. Description of the Related Art Conventionally, as a film defect inspection apparatus for inspecting defects of a sheet-like film which is sequentially taken in, an image of the film is captured by a CCD line sensor, the brightness level of the film surface is detected by image processing, and the brightness thereof is detected. There is provided an inspection device that compares the level to a certain threshold value and determines that the film is defective if the brightness level exceeds the threshold value.

[0003]

In this inspection apparatus, the detected brightness level of the film surface is compared with a fixed threshold value.

By the way, in the sheet-shaped film that is sequentially taken off, the brightness (luminance) of the color may be different at the beginning and the end of the film that is taken out.

FIG. 4 shows an example of changes in the image level (luminance level) at this time.

The brightness level of the film imaged by the CCD line sensor has a sufficient difference with respect to the threshold value A at the beginning. For example, a defective portion (color unevenness) such as partial loss of color and thinning occurs. In (), since the brightness level exceeds the threshold value A (indicated by reference numeral 81), it is possible to inspect the film for defects.

However, in this type of film, the film taken out from the molding machine may have a higher brightness level, that is, a brighter color, as compared with the brightness level at the beginning of the film taking. Therefore, if the same threshold value A is used from the beginning to the end of the take-up, it is determined that there is a defect only because the color is bright even though the film itself has no defect. Occurs.

On the other hand, even if the brightness level of the film becomes high, there is no problem, and if the color of the film changes greatly at the beginning and at the end, there is still a problem as a product.

In the above example, the film taken out from the molding machine has a higher brightness level as compared with the brightness level at the beginning of the film taking, but when the brightness level becomes lower, the brightness level becomes lower. That is, the color may become darker. Then, also in this case, the same problem as described above occurs.

The present invention was devised to solve the above-mentioned problems, and its purpose is to change the threshold value according to the change of the brightness level of the film drawn from the molding machine and set the changeable upper limit value. By doing so, it is an object to provide a film defect inspection apparatus capable of performing an appropriate defect inspection in accordance with actual film take-off molding.

[0011]

A film defect inspecting apparatus of the present invention is a film defect inspecting apparatus for inspecting defects of a sheet-like film which is sequentially taken in, and an image pickup means for continuously picking up the film. A brightness detecting unit that detects the brightness level of the film surface from the image of the film captured by the image capturing unit and a brightness level detected by the brightness detecting unit are compared with a threshold value. If the brightness level exceeds the threshold value, the film is detected. And a threshold value for sequentially changing the threshold value to a value obtained by adding a constant value to the average value of the brightness levels of the latest several images after the comparison or a value obtained by integrating the threshold values. And a setting control means. In addition, as the imaging means,
It is possible to use a CCD line sensor.

According to the present invention having such characteristics,
The threshold value setting control means is configured to sequentially change the threshold values so that the average value of the brightness levels of the latest several images after comparison becomes a value obtained by adding a constant value. As a result, even if the film taken out from the molding machine has a higher brightness level, that is, the color becomes brighter as compared with the brightness level at the start of the film taking, the brightness level changes Accordingly, the threshold value also fluctuates to an appropriate value, so that it becomes possible to reliably determine the defect that has occurred in the film.

Further, according to the film defect inspection apparatus of the present invention, it further comprises storage means for storing the upper limit value of the threshold value in advance, and the threshold value setting control means stores the set threshold value and the storage means. Compare with the upper limit at any time,
When the set threshold value exceeds the upper limit value, the subsequent threshold value is fixed to the upper limit value.

According to the present invention having such characteristics,
Even when the brightness level of the film changes rapidly and the color of the film changes greatly between the start and the end, it is possible to determine that the product is defective.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an overall configuration diagram showing an embodiment of a film defect inspection apparatus of the present invention.

The film defect inspection device is a device for inspecting the color irregularity of the film 1 taken in from a molding machine (not shown) and the inclusion of foreign matter (dust) as defects.

That is, an illumination (fluorescent lamp) 2 for irradiating light on a sheet-shaped film 1 which is sequentially taken in, and a CCD as an image pickup means arranged so as to take in the light reflected by the resin film 1 (reflected light). It comprises a line sensor 3 and an image processing device 4 for processing a film image captured by the CCD line sensor 3. The image processing device 4 also includes a brightness detection unit 41 that detects the brightness level of the surface of the film 1 from the captured film image,
The brightness level detected by the brightness detection unit 41 is compared with a threshold value B, and when the density value exceeds the threshold value B, the determination unit 42 that determines that the film 1 has a defect and this threshold value B are the latest values after the comparison. When a threshold value is determined to be defective by the threshold value setting control unit 43 and the determination unit 42, the threshold value setting control unit 43 sequentially changes the value to a value obtained by adding a certain value to the average value of the brightness levels of several images or an integrated value. Has an alarm unit 45 for issuing an alarm.

The image processing apparatus 4 further includes a storage unit 44 that stores the upper limit C of the threshold B in advance, and the threshold setting control unit 42 sets the set threshold B and the storage unit 4.
3 is compared with the upper limit value C stored in 3 at any time, and when the set threshold value B exceeds the upper limit value C, the subsequent threshold value B is fixed to the upper limit value C (B = C). There is.

As shown in FIG. 1, the fluorescent lamp which is the illumination 1 is arranged along the width direction of the film 1 at a position above the film 1 and with respect to the irradiation point (irradiation line) L. It is arranged keeping an inclination of about 25 degrees.

On the other hand, the CCD line sensor 3 is also disposed on the opposite side of the fluorescent lamp 1 with the irradiation line L sandwiched above the film 1, and is also about 25 degrees with respect to the irradiation line L. It is arranged keeping the inclination of.

Here, as the film 1 to be inspected,
In this embodiment, the transparent resin is formed into a thin film, and the color is blue and transparent. The film width is 9
It is 00 mm. Furthermore, the take-up speed is 3 m / mi
It is n.

The image resolution of the CCD line sensor 3 is set to 0.1 mm according to the flowing speed of the film 1. However, the number of dots in one line is 5000 bi
t, the clock frequency is 10 MHz. As a result, the detectable defects are color unevenness (spots): φ5 mm or more and foreign matter (dust): φ0.2 mm or more.

The film defect inspection apparatus of this embodiment is
Since the arrangement is such that the reflected light of the illumination 1 is taken in by the CCD line sensor 3, the brightness of the image changes depending on the reflectance of the film 1. The reflectance of this film 1 changes depending on the thickness of the thin film formed on the surface, and if the reflectance exceeds 40%, it cannot be realized as a product.

In a normal image, the level average of the inspection image is 65, but it has been previously confirmed by experiments that the level average becomes 90 when the reflectance exceeds 40%. Here, (image level: 256 gradation gray scale).

Therefore, in the present embodiment, if the upper limit value C of the threshold value B is set to 90, even if the reflectance is too high and the change in color brightness is too large, it is detected as a defect. be able to. As a result, by varying the threshold value B in accordance with the overall level, it is possible to stably detect color irregularities and foreign matter of normal inspection items.

The threshold setting control by the threshold setting controller 42 will be described.

The threshold setting control unit 42, as described above,
The setting is sequentially changed to a value obtained by adding a constant value to the average value of the brightness levels of the latest several images after comparison detected by the brightness detection unit 41 or an integrated value. In this case, when obtaining the average value of the brightness levels of several images, the maximum value and the minimum value thereof may be removed and the average value of the brightness levels of the remaining images may be taken. As a result, it is possible to eliminate a luminance level irregularly generated by noise or the like, and it is possible to obtain a more accurate average value.

FIG. 2 shows an example of the inspection operation of the film defect inspection apparatus of this embodiment.

In FIG. 2, when the film 1 is started to be taken, the change in the brightness level of the surface of the film 1 detected by the brightness detecting section 41 from the start to the end is shown by a solid line. In response to this change in the brightness level, in the present embodiment, the threshold setting control unit 42 changes the threshold B so as to correspond to the change in the brightness level. The change indicated by the broken line in FIG. 2 indicates the change in the threshold value B.

That is, in the conventional film defect inspection apparatus, since the brightness level of the film 1 exceeds the conventional threshold value A at the point a in the flow direction of the film 1, all the defects are judged as defects thereafter. However, in the film defect inspection apparatus of the present embodiment, since the threshold value B is maintained at a level where defects can be inspected even at the point a, the color unevenness included in the film 1 after the point a is also uneven. It is possible to accurately inspect (detect) foreign matter and foreign matter.

On the other hand, if the variation of the threshold value B is allowed to an unlimited extent in this way, even if the color of the film 1 is greatly changed at the beginning and at the end, and the product cannot be shipped as a product, this is not possible. It cannot be detected as a defect. Therefore, in the present embodiment, the upper limit value C is provided for such a variation of the threshold value B, and as described above,
This upper limit value C is set to 90. That is, 90, which is the upper limit value C, is stored in the storage unit 44.

FIG. 3 shows that when the upper limit value C is set,
The example of the inspection operation of the film defect inspection device is shown.

That is, as described above, the threshold value setting control unit 42 adds or adds a constant value to the average value of the brightness levels of the most recent images after comparison detected by the brightness detection unit 41, or integrates them. The settings are being changed sequentially so that the values will be set.

Therefore, at the beginning and the end of the film 1 being taken, the threshold value B gradually rises according to the change in the brightness level. Then, when the value of the threshold value B reaches the upper limit value C stored in the storage unit 44 at the point b in the take-up direction, thereafter, the upper limit value C is fixed as the threshold value B and compared with the brightness level. To do.

As a result, the luminance level exceeds the threshold value B (= C) at the point c in the take-up direction, so that in the subsequent inspection, the color of the film 1 is too bright, and the entire film 1 is defective. It becomes possible to judge. That is, even when the brightness level of the film 1 changes rapidly and the color of the film greatly changes between the beginning and the end of the take-up, it can be determined that the product is defective.

When the determination unit 42 determines that the defect is a defect, the alarm unit 45 issues an alarm. The alarm means at this time may be, for example, a buzzer sounding or a lamp lighting. Further, when it is determined that there is a defect, the molding machine may be stopped immediately.

In the above embodiment, the film 1 is used.
Exemplifies a case where the luminance level becomes higher toward the later side than the luminance level at the start of taking-up, but conversely, when the luminance level becomes lower, that is, when the color becomes darker, the present invention is similarly applied. It is possible to

[0039]

According to the film defect inspection apparatus of the present invention, the threshold value setting control means has a value obtained by adding a constant value to the average value of the brightness levels of the latest several images after the comparison or a value obtained by integrating the values. As described above, the thresholds are sequentially set and changed. As a result, even if the film taken out from the molding machine has a higher brightness level, that is, the color becomes brighter as compared to the brightness level at the start of the filming, that is, the brightness level changes. Accordingly, the threshold value also changes to an appropriate value, so that it is possible to reliably determine the defect that has occurred in the film.

Further, according to the film defect inspection apparatus of the present invention, it further comprises storage means for storing the upper limit value of the threshold value in advance, and the threshold value setting control means has the upper limit value stored in the set threshold value and the storage means. The value is compared with the value at any time, and if the set threshold value exceeds the upper limit value, the subsequent threshold value is fixed to the upper limit value. As a result, even when the brightness level of the film changes rapidly and the color of the film changes greatly between the start and the end, it can be determined that the product is defective.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of a film defect inspection device of the present invention.

FIG. 2 is an explanatory diagram showing an example of an inspection operation of the film defect inspection apparatus of the present embodiment.

FIG. 3 is an explanatory diagram showing an example of the inspection operation of the film defect inspection apparatus when the upper limit value of the threshold value is set.

FIG. 4 is an explanatory diagram showing a change in the brightness level of the film surface being taken off.

[Explanation of symbols]

1 film 2 Lighting (fluorescent lamp) 3 CCD line sensor 4 Image processing device 41 Luminance detector 42 Judgment section 43 Threshold setting control unit 44 memory 45 Alarm unit

Claims (3)

[Claims] 1. A film defect inspection apparatus for inspecting defects of a sheet-shaped film which is sequentially taken out, comprising: an image pickup means for continuously picking up the film, and a film surface from the image of the film picked up by the image pickup means. Brightness detecting means for detecting the brightness level of the, and comparing the brightness level detected by the brightness detecting means with a threshold value, if the brightness level exceeds the threshold value, determining means to determine that there is a defect in the film, the threshold value , A film comprising a threshold setting control means for sequentially changing the setting so as to be a value obtained by adding a constant value to the average value of the brightness levels of the latest several images after the comparison or an integrated value. Defect inspection equipment. 2. The apparatus further comprises a storage unit that stores the upper limit value of the threshold value in advance, and the threshold value setting control unit compares the set threshold value with the upper limit value stored in the storage unit at any time, and sets the upper limit value. The film defect inspection apparatus according to claim 1, wherein when the threshold value exceeds the upper limit value, the subsequent threshold value is fixed to the upper limit value. 3. The film defect inspection apparatus according to claim 1, wherein the image pickup means is a CCD line sensor.