JPH0611457A - Method and device for sensing foreign matter in film - Google Patents

Abstract

PURPOSE:To provide a method and device for effectively sensing any photo- transmissive foreign matter(s) in a photo-transmissive film even when the film and foreign matters have the same color (including transparent). CONSTITUTION:A film 1 is stretched in a sensing device for foreign matter(s) included in the film, wherein a light source 5 and a dark colored background member 6 are arranged on one side of the set film 1 while a photographing device 7 is installed on the other side of the film 1. The photographing device 7 is equipped with a processing part 9 which reads the transmitted light through the film 1 with the member 6 as the backdrop and judges whether the film includes any foreign matter(s).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for detecting foreign matter in a film.

[0002]

2. Description of the Related Art The surface of a roller of a copying machine is covered with a transparent film. This transparent film is formed into a tube shape by an extrusion molding machine, and the tube is covered with a roller and contracted so as to be in close contact with the surface of the roller.
When the tubular film is formed by the extruder, the resin pellets may not be completely melted and may remain in the form of fine particles, and the fine particles may be mixed in the film. When the fine particles are mixed in the film, the thickness of the film is increased only in that portion, and the thickness is not uniform.

When a roller is coated with such a film containing unmelted fine particles, a convex portion is formed on the roller surface, and this convex portion may adversely affect the copy paper, resulting in a copy failure. Therefore, it was necessary to examine the presence of unmelted microparticles in the film. As a method for detecting foreign matter in a film, when the foreign matter is a colored matter, for example, the technique described in Japanese Patent Publication No. 1-57182 can be applied.

In this conventional technique, a subject is irradiated with strobe light, and the reflected light and the transmitted light are read by an image pickup device to detect a foreign substance. Further, the above-mentioned publication also discloses a technique of irradiating a subject with laser light, detecting reflected light and transmitted light thereof with a line sensor, and discriminating foreign matter.

[0005]

However, in the case of the film for coating the roller of the copying machine, since the film is transparent and the fine particles are also transparent, it is extremely difficult to detect using the known technique of strobe light. It was difficult. That is, if this technique is used, an ultra-high-sensitivity TV camera capable of detecting a minute change in light is required, and the signal processing thereof is complicated, which is extremely expensive. It was

Further, when a laser is used, it is necessary to scan the laser spot at a high speed with a rotating mirror, which causes a problem that the structure becomes complicated. Therefore, conventionally, in order to detect transparent foreign substances in a transparent film, it has been necessary to rely on a visual inspection by a seasoned inspector. However, in the manual inspection, a minute change in light is discriminated, so that concentration is required, the inspection cannot be performed for a long time, and the efficiency cannot be improved.

Therefore, the present invention provides a method and an apparatus for efficiently detecting a translucent foreign substance in a translucent film in which the color of the film (including transparency) and the color of the foreign substance are the same. The purpose is to provide.

[0008]

In order to achieve the above object, the present invention takes the following means. That is, the feature of the method for detecting foreign matter in the film of the present invention is that the light from the light source is applied to the stretched film, and the transmitted light passing through the film is read by setting the dark background as the background. The point is to detect foreign matter in the film.

The detection device of the present invention is characterized in that the light source and the dark background member are arranged on one side of the stretched film, and the image pickup device is arranged on the other side of the film. The image pickup device has a processing unit that reads the transmitted light that has passed through the film with the dark background member as a back and determines a foreign substance in the film.

[0010]

According to the present invention, the film is irradiated with light from the light source, and this light passes through the film. When a foreign substance is present in the film, if the foreign substance has a minute convex shape, the light passing through the foreign substance is condensed at a certain focal point by the lens effect. However, when the transmitted light is observed in the field of view including the light source, the light source is also observed at the same time, and thus the difference between the brightness of the focus and the brightness of the light source cannot be clearly identified.

Therefore, in the present invention, the transmitted light is observed with the dark background as the background. That is, of the light from the light source, the ones that pass through the foreign matter and the ones that pass through the normal part have different refractive indexes, and therefore their optical paths are different. Therefore, on the optical path of the transmitted light that has passed through the foreign matter,
By looking at the transmitted light against a dark background, the presence of foreign matter can be determined very easily.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 3, a film 1, which is a sample, is transparent and has a tube shape, and the tube is formed into a flat band shape and wound by a winder 2. The film 1 in the winding process moves at a predetermined speed and is given a predetermined tension. The moving speed or moving length of the film 1 is detected by the encoder 3.

A foreign matter detector 4 is arranged between the encoder 3 and the winder 2. The detection unit 4 is a film 1
It is composed of a light source 5 and a dark background member 6 arranged below, and an image pickup device 7 arranged above. The light source 5 is composed of a high frequency lighting fluorescent lamp. The dark background member 6
Are arranged between the light source 5 and the film 1. The background member 6 is formed of a plate material, and the upper surface of the background member 6 is a black plane. A slit 8 for irradiating the film 1 with the light from the light source 5 is formed in the background member 6 with a predetermined width.

The image pickup device 7 comprises an industrial television camera. The image pickup device 7, the light source 5, and the slit 8
Are arranged on a substantially straight line. This imaging device 7
A processing unit 9 for reading the transmitted light that has passed through the film 1 from the light source 5 and electrically processing the imaged data to determine the presence of foreign matter in the film 1 is connected. The encoder 3 is connected to the processing unit 9.

A marker device 10 is connected to the processing section 9. The marker device 10 includes the detection unit 4 and the winder.
It has a sticker sticking part 11 which is placed between the sticking part and the sticking part and sticks a sticker to the moving film. When a foreign substance is detected by the detection unit 4, the feed length of the film 1 is monitored by the encoder 3, and when the foreign substance passes through the sticking unit 11, the processing unit 9 sends a sticking signal to the marker device 10 to detect the foreign substance. Attach a seal near it.

1 and 2 show the details of the detecting section 4 and the principle of processing in the processing section 9. As shown in FIG. That is, since the foreign matter 12 present in the film is unmelted fine particles of resin pellets mixed in during extrusion molding, the shape is convex. Therefore, the light source 5 that has passed through the slit 8
When passing through the foreign substance 12, the light beam from is refracted by the lens effect and is condensed on the image pickup element surface of the image pickup device 7.

Now, the foreign matter 12 is at the center of the light source 5 and the slit 8
When moving on the line connecting the center of the light source (point A in FIGS. 1 and 2), the light from the light source 5 directly enters the image sensor surface, so that the image signal levels of the foreign matter 12 and the non-foreign matter are different. There is no difference and the processing unit 9 cannot determine. However, when the foreign matter 12 is moving at the position of the point B in FIGS. 1 and 2, that is, when it is in the vicinity of the slit 8, since the upper surface of the background member 6 is black, There is a large level difference between the video signals, and the presence of the foreign matter 12 can be determined.

If the point B is an adhering foreign matter such as dust, the foreign matter does not pass through the light, so that it becomes the same as the dark color of the background and cannot be detected. That is, the present invention has a characteristic that it detects transparent convex foreign matter, but does not detect foreign matter such as adhered matter. FIG. 4 shows another embodiment of the present invention in which the background member 6 and the light source 5 are provided separately from each other, and the image pickup device 7 faces the background member 6.

Even with the configuration shown in FIG. 4, the light from the light source 5 is largely refracted by the light passing through the foreign substance 12, or is reflected and enters the image pickup device 7. Can be distinguished from. Then, since the foreign substance transmitted light is viewed with the dark background member 6 as the back, the discrimination can be facilitated. The present invention is not limited to the above-mentioned embodiments, and a translucent film or a colored film can be applied as long as it is a translucent film.
Further, the color of the background member is not limited to black and may be any dark color.

Further, the detection method of the present invention includes the case of visual observation.

[0021]

According to the present invention, when a translucent convex foreign substance is present in the translucent film, the foreign substance can be detected very easily. Then, it is possible to detect only the translucent convex foreign matter without erroneously detecting small dust and the like, and therefore, the inspection step for the foreign matter can be omitted.

[Brief description of drawings]

FIG. 1 is a front view of a main part of an embodiment of the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is an overall configuration diagram of an embodiment of the present invention.

FIG. 4 is a front view of an essential part showing another embodiment of the present invention.

[Explanation of symbols]

 1 Film 5 Light Source 6 Background Member 7 Imaging Device 9 Processing Section

Claims (2)

[Claims] 1. A foreign matter in a film is detected by irradiating a stretched film with light from a light source and reading the transmitted light passing through the film with a dark background as a background. Foreign matter detection method in film. 2. A light source and a dark background member are arranged on one side of the stretched film, and an image pickup device is arranged on the other side of the film. And a foreign matter detecting device for detecting a foreign matter in the film by reading the dark background member as a back.