JP3806557B2 - Heat seal position detection device for plastic film - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a heat seal position detecting device for a plastic film.
[0002]
[Prior art and its problems]
For example, in a bag making machine that manufactures plastic bags, a micro uneven surface of a pattern such as a mesh is formed on the heat seal portion of the plastic film, the plastic film is intermittently fed in the length direction, is run, and the heat seal portion or In the vicinity, the plastic film is often cut by a cutter. In this case, it is required to accurately cut the plastic film at or near the heat seal portion, and in order to achieve this, when the plastic film is traveling in the length direction, the heat seal position of the plastic film in advance is required. Need to be detected. Therefore, before filing this application, the applicant developed and proposed a new type of heat seal position detection device. This is what is described in JP-A-11-190608.
[0003]
In the apparatus disclosed in the publication, a light source and an optical sensor face a plastic film, and light is emitted from the light source. The optical sensor receives reflected light or transmitted light from the plastic film. Therefore, when the heat seal part reaches the installation position of the light source and the optical sensor, the reflected light or transmitted light is redirected by the minute uneven surface of the heat seal part, and the amount of light received by the optical sensor changes. When a difference in the wave shape occurs in the amount of light received by the optical sensor in the width direction of the plastic film, the minute uneven surface of the heat seal portion is read by the waveform. In this case, the heat seal position of the plastic film is detected. However, in the case of the apparatus disclosed in the publication, the heat seal position of the plastic film may not actually be detected, and there is a problem in its reliability. The reason is considered to be the relationship between the minute uneven surface of the heat seal portion and the amount of light received by the optical sensor. As the plastic film travels, it is clear that the reflected light or transmitted light is periodically redirected on the minute uneven surface of the heat seal portion, but the direction of the deflection is extremely complicated. Therefore, even if it changes periodically, the difference in the wave shape does not necessarily occur in the amount of light received by the optical sensor, and the fine uneven surface of the heat seal portion cannot be read by the waveform, and the heat seal of the plastic film It is thought that the position cannot be detected.
[0004]
OBJECT OF THE INVENTION
Therefore, the present invention has been made for the purpose of reliably detecting the heat seal position of the plastic film.
[0005]
[Structure of the invention]
According to the invention, in the apparatus for detecting the heat seal position of the plastic film having a heat seal portion having a fine uneven surface of a pattern such as a mesh and traveling in the length direction, a plurality of light sources are attached to the plastic film. It arrange | positions at intervals in the parallel direction, each light source opposes a plastic film, and light is irradiated from each light source. Further, the optical sensor faces the plastic film, receives reflected light or transmitted light from the plastic film, and recognizes the image. Therefore, the minute uneven surface of the heat seal portion can be read by the image change, and the heat seal position of the plastic film can be detected. Furthermore, according to the present invention, the pinpoint mask or the small-diameter lens is disposed between the optical sensor and the plastic film, and the reflected light or transmitted light image is sharpened by the pinpoint mask or the small-diameter lens.
[0006]
The light source is preferably a parallel light source.
[0007]
[Explanation of Examples]
Examples of the present invention will be described below.
[0008]
Prior to the description of the embodiment, first, the reference example of FIG. 1 will be described. This is for detecting the heat seal position of the plastic film 1 and is an accessory device of the bag making machine. It is the same as that of the said gazette that it overlaps, is intermittently sent in the length direction X, and drive | works. Each time the plastic film 1 is intermittently fed, the plastic film 1 is heat-sealed in the width direction, and then, every intermittent feed, the plastic film 1 is cut by a cutter at or near the heat-sealed portion 2, thereby a plastic bag. Is manufactured in the same manner as that of the publication. The Teflon sheet or the minute uneven pressing surface of the seal bar or cooling bar is pressed against the heat seal portion 2 to form a minute uneven surface of a pattern such as a mesh on the heat seal portion 2 as in the same publication.
[0009]
In this apparatus, on the upper side of the plastic film 1, the light source 3 and the optical sensor 4 face the plastic film 1, and light is emitted from the light source 3, and the optical sensor 4 receives the reflected light of the plastic film 1. The position is a position downstream of the seal bar and the cooling bar, and is a position upstream of the cutter. Further, in this apparatus, light from the light source 3 is obliquely irradiated on the upper surface of the plastic film 1, reflected obliquely, and guided to the optical sensor 4.
[0010]
Further, a light blocking mask 5 is disposed between the light source 3 and the plastic film 1, and a pinpoint mask 6 is disposed between the optical sensor 4 and the plastic film 1. As shown in FIG. 2, the light blocking mask 5 has a plurality of slits 7 through which light passes. Therefore, the light from the light source 3 passes through the slits 7 and is applied to the plastic film 1. The light is reflected from the plastic film 1, passes through the pinpoint mask 6, and is guided to the optical sensor 4. The optical sensor 4 is a CCD camera. Therefore, the image of the slit 7 of the light blocking mask 5 can be recognized by the optical sensor 4. When the image of the slit 7 of the light blocking mask 5 is recognized, the pinpoint mask 6 can also sharpen the image. The pinpoint mask 6 has a pinpoint diameter of 1.0 mm to 6.0 mm.
[0011]
When the plastic film 1 travels in the length direction and the heat seal portion 2 reaches the installation position of the light source 3 and the optical sensor 4, the light from the light source 3 passes through each slit 7 and the minute unevenness of the heat seal portion 2. It reaches the surface and is reflected from the minute uneven surface of the heat seal portion 2, but the reflected light is redirected by the minute uneven surface of the heat seal portion 2. Further, as the plastic film 1 travels, the minute uneven surface of the heat seal portion 2 has an amplitude A with reflected light and periodically changes as shown in FIG. Therefore, when the reflected light of the heat seal portion 2 is guided to the optical sensor 4, the image of the slit 7 is disturbed and changed thereby.
[0012]
Further, in this apparatus, the width W of each slit 7 of the light blocking mask 5 is selected to be 0.5 to 5 mm, and the pitch P0 is selected to be 10 to 100 mm. As a result, the pitch P1 of each slit 7 on the image is smaller than the periodic deflection amplitude A of the reflected light of the heat seal portion 2, and the image of the slit 7 is reliably disturbed and changed. Therefore, the minute uneven surface of the heat seal portion 2 can be read by the image change, and the heat seal position of the plastic film 1 can be reliably detected.
[0013]
As shown in FIG. 4, a plurality of holes 8 may be formed in the light blocking mask 5, and light may pass through the holes 8. In this case, the optical sensor 4 can recognize an image of the hole 8 of the light blocking mask 5. The diameter D of each hole 8 of the light blocking mask 5 is selected to be 0.5 to 5 mm, and the pitch P0 is selected to be 10 to 100 mm as in the slit 7 of FIG. Therefore, the pitch of each hole 8 on the image is smaller than the periodic deflection amplitude A of the reflected light of the heat seal portion 2, and the image of the hole 8 is surely disturbed and changed. The minute uneven surface can be read and the heat seal position of the plastic film 1 can be detected.
[0014]
FIG. 5 shows an embodiment of the present invention. In this embodiment, a plurality of light sources 3 are arranged around the optical sensor 4, and light from the light source 3 is obliquely irradiated on the upper surface of the plastic film 1, reflected, and guided to the optical sensor 4. The light blocking mask 5 is disposed between the light source 3 and the plastic film 1, and the pinpoint mask 6 is disposed between the optical sensor 4 and the plastic film 1, as in the reference example of FIG. Therefore, when the reflected light of the heat seal portion 2 is guided to the optical sensor 4, the minute uneven surface of the heat seal portion 2 can be read by the image change, and the heat seal position of the plastic film 1 can be detected.
[0015]
In the embodiment of FIG. 5, the light source 3 and the optical sensor 4 may be arranged on the lower side of the plastic film 1 instead of the upper side.
[0016]
6 is a reference example, the optical sensor 4 may be opposed to the plastic film 1 on the opposite side of the light source 3 as shown in FIG. When the light blocking mask 5 is disposed between the light source 3 and the plastic film 1 and the pinpoint mask 6 is disposed between the optical sensor 4 and the plastic film 1, the optical sensor 4 receives the transmitted light of the plastic film 1, and the optical sensor. 4, the slit 7 or the hole 8 of the light blocking mask 5 can be recognized. Therefore, when the transmitted light of the heat seal portion 2 is guided to the optical sensor 4, the image of the slit 7 or the hole 8 is disturbed and changed thereby, and the micro uneven surface of the heat seal portion 2 is read by the image change, and the plastic The heat seal position of the film 1 can be detected.
[0017]
In the embodiment of FIG. 5, instead of the pinpoint mask 6, a small-diameter lens may be disposed between the optical sensor 4 and the plastic film 1, and the image of the slit 7 or the hole 8 may be sharpened by the small-diameter lens.
[0018]
In the embodiment of FIG. 7, a plurality of light sources 3 are arranged around the optical sensor 4 at intervals. For example, the four light sources 3 are arranged at an angular interval of 90 °. The size of the interval is 10 to 100 mm. For example, the light source 3 is a parallel light source, and generates a parallel light beam having a diameter of about 30 mm. The interval is approximately 50 mm. And each light source 3 opposes the plastic film 1, light is irradiated from each light source 3, and the optical sensor 4 receives the reflected light of the plastic film 1, and recognizes it as an image. Therefore, the minute uneven surface of the heat seal portion 2 can be read by the image change, and the heat seal position of the plastic film 1 can be detected. The optical sensor 4 may be disposed on the opposite side of the light source 3 so that the optical sensor 4 receives the light transmitted through the plastic film 1 and recognizes the image.
[0019]
In the embodiment of FIG. 7, it is preferable to arrange the pinpoint mask 6 between the optical sensor 4 and the plastic film 1 because the pinpoint mask 6 can sharpen the image of reflected light or transmitted light. Instead of the pinpoint mask 6, a small-diameter lens may be disposed between the optical sensor 4 and the plastic film 1, and the reflected-light or transmitted-light image may be sharpened by the small-diameter lens. Furthermore, the light source 3 may be a light source other than a parallel light source, a point light source, or a linear light source. A laser light source may be used as the light source 4. Further, a lens may be disposed between the light source 3 and the plastic film 1 and condensed on the plastic film 1 by the lens. The light source 3 may be covered with a reflecting mirror and condensed on the plastic film 1 by the reflecting mirror.
[0020]
【The invention's effect】
As described above, according to the present invention, the plurality of light sources 3 face the plastic film 1, and light is emitted from each light source 3, and the reflected light or transmitted light of the plastic film 1 is image-recognized by the optical sensor 4. The minute uneven surface of the heat seal portion 2 is read by the image change. Therefore, the heat seal position of the plastic film 1 can be reliably detected, and the intended purpose can be achieved.
[Brief description of the drawings]
FIG. 1 is a side view showing a reference example.
FIG. 2 is a plan view of the light blocking mask of FIG.
3 is an explanatory diagram showing a relationship between an image of a slit of the apparatus of FIG. 1 and reflected light of a heat seal portion.
FIG. 4 is a plan view showing another reference example.
FIG. 5 is a side view showing an embodiment of the present invention.
FIG. 6 is a side view showing another reference example.
FIG. 7 is a side view showing another embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Plastic film 2 Heat seal part 3 Light source 4 Optical sensor 5 Light shielding mask 6 Pinpoint mask 7 Slit 8 Hole

Claims (2)

A device for detecting the heat seal position of a plastic film that has a micro uneven surface of a pattern such as a mesh and that runs in the length direction,
A plurality of light sources arranged at intervals in a direction parallel to the plastic film, facing the plastic film and irradiating light;
Opposing the plastic film, receiving the reflected or transmitted light of the plastic film, recognizing the image, reading the micro uneven surface of the heat seal portion by the image change, and detecting the heat seal position of the plastic film An optical sensor;
A heat seal position detection device for a plastic film, which is disposed between the optical sensor and the plastic film and includes a pinpoint mask or a small-diameter lens that sharpens an image of the reflected light or transmitted light.   The apparatus of claim 1, wherein the light source comprises a parallel light source.

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