JP2002046943A - Plastic core for taking up sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a roll from slipping off from a core without fixing an end of a sheet to the core in taking up the sheet strip onto the core in the rolled shape. SOLUTION: This plastic core used for taking up the sheet strip into the rolled shape, has a sheet taking-up zone on an approximately center of a cylindrical core body, and projections are respectively formed on both edges in the sheet taking-up zone.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylindrical core member for winding a belt-like sheet made of paper, plastic film or the like thereon.

[0002]

2. Description of the Related Art In the past, many thermal printers were used as output printers built in facsimile machines. However, images printed on thermal paper are poor in storability. A thermal transfer printing type for printing on plain paper has been widely used. Such a thermal transfer printer usually has a delivery roll in which a belt-shaped thermal transfer ink sheet having the same width as the recording paper is wound around a cylindrical core, and a winding core for winding a used ink sheet into a roll. The ink sheet pulled out from the feed roll and the recording paper are overlapped, and an image is formed on the recording paper by heating from the ink sheet side according to the image information with a thermal head, and the used ink sheet is wound up. It is configured to be wound around a core. In this case, as shown in FIG. 1, the replacement ink sheet is supplied in a state in which the delivery roll 11 and the take-up core 12 are connected (the leading end of the sheet is taken up by the take-up core). When replacing an ink sheet, it is common to replace the ink sheet with a set of a delivery roll and a winding core.

[0003] A thermal transfer ink sheet generally comprises a thin film base made of a heat-resistant plastic provided with a layer made of a heat-meltable or sublimable ink.
If necessary, a heat-resistant layer made of a fluororesin or the like may be provided on the surface of the substrate opposite to the side on which the ink layer is provided (the surface on the side to which the thermal head is applied). Conventionally, a paper tube has been used as a core for winding such a thermal transfer ink sheet, and as shown in FIG. 2, plastic caps 21 and 22 having a supporting shaft portion and a driving gear formed on the paper tube 23. However, since it is troublesome to remove or fit a plastic cap on the paper tube every time the ink sheet is replaced, the entire core, including the shaft and gears, is made of plastic. Has been developed. In the case of the integral core, the replacement is performed including the shaft portion and the gear portion, so that the above-mentioned inconvenience is eliminated and the user's labor of replacing the ink sheet is reduced.

[0004]

However, if the entire core is made of plastic, for example, when exchanging the ink sheet, there is a fear that the roll of the ink sheet slips in the axial direction of the core and falls off. I understood. This is because the plastic core generally has a large surface smoothness, so that the friction between the inner surface of the sheet roll wound on the core and the surface of the core is small and the core is slippery. Therefore, a core has been proposed in which the surface on which the ink sheet is wound is subjected to a concavo-convex processing such as embossing. However, while performing such unevenness processing causes an increase in manufacturing cost, the effect of preventing slippage may not always be sufficient. In addition, a concave and convex mold may be attached to the film, and the mold may appear on the transferred image, or may adversely affect the transportability of the ink sheet.

However, if it is only necessary to prevent the sheet roll from falling off the core, the winding start end of the ink sheet may be fixed to the core by, for example, a double-sided tape. However, if the ink sheet having the fixed end is used as a feeding roll, the ink sheet does not separate from the core when the ink sheet is used up, and a load is applied to the ink sheet feeding mechanism of the printer. In order to prevent this, an end detection mechanism must be provided to detect the end of the ink sheet and stop the sheet feeding just before the ink sheet is used up. on the other hand,
If the end of the ink sheet is not fixed to the core, the ink sheet is separated from the core when the ink sheet is used up, so that no load is applied to the ink sheet feeding mechanism,
Such a complicated end detection mechanism is not always necessary. If it is desired to prevent the thermal head from idling due to the lack of the ink sheet, a simple optical mechanism for detecting the presence or absence of the ink sheet may be provided.

In the above description, an example has been described in which a thermal transfer ink sheet having a plastic film as a base material is wound into a roll. However, when a belt-shaped sheet is wound around a core to form a roll, the sheet roll becomes a core. The problem of slipping out of the thermal transfer ink sheet is not necessarily limited to the case where the thermal transfer ink sheet is wound. That is, the problem to be solved by the present invention is that when a belt-shaped sheet is wound into a roll on a core, the roll does not slip off the core without fixing the end of the sheet to the core. Is to provide things.

[0007]

The present invention relates to a plastic core for winding a belt-shaped sheet into a roll, which has a sheet winding area 2 substantially at the center of a cylindrical core body 1. A plastic core characterized in that projections 3 are formed at both edges in a sheet winding area, respectively, is provided, thereby solving the above problem.

[0008]

The cause of the sheet roll falling off the core is basically due to the fact that the core has a cylindrical shape and thus the sheet roll has a degree of freedom to move in the axial direction of the core. In the past, frictional force between the core surface and the inner surface of the sheet roll caused by winding the sheet with a certain degree of tension prevented the axial movement of the sheet roll, but the core was made of plastic. Therefore, the problem that the sheet roll comes off comes out because the frictional force is greatly reduced. Therefore, as a means for solving the problem, it is conceivable that one of the measures is to increase the reduced frictional force to the same level as when using a paper tube as in the past, and this is a method of forming unevenness on the core surface. It leads to the idea of applying. However, if the core is left at high temperature and then returned to room temperature, the expansion and contraction rates of the core and the rolled ink sheet differ, and the winding often becomes loose. May come off.

However, the present invention is based on another solution, namely, the idea of providing the core with a stopper for preventing the movement of the sheet roll. Speaking of such a stopper, the first thing that comes to mind is the flange, but forming the flange integrally with the core has manufacturing difficulties, and the sheet is made by exactly matching the flange with the edge of the sheet. Since the sheet has to be wound, there is a disadvantage that the tolerance of an axial error at the time of sheet winding is small. In view of this, the present invention employs a contrivance in which projections are provided at both edges of the core in the sheet winding region. The projections in this case have the same effect as enlarging the diameter of both edges of the sheet winding area, and the sheet roll is wound up in such a manner that both edges are slightly swollen. Therefore, even if the sheet roll attempts to move in the axial direction of the core, since the sheet roll is swollen, the resistance to move is large, and such movement is effectively suppressed.

As can be seen from the above description, the projections may play a role equivalent to an increase in the diameter of the core at that portion, and may not necessarily increase the friction with the sheet roll or cut into the sheet roll. It has to be noted that it is not necessary to have a shape that That is, even if the projection does not have a sharp or rough tip, for example, a projection with a round head is sufficient to prevent the sheet roll from falling off the core. However, if it is necessary to strictly suppress slippage of the sheet roll, it is preferable to have a trapping effect. For such a purpose, for example, a ring-shaped projection having a triangular cross section is suitable.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, a preferred use of the plastic core of the present invention is a core for winding a thermal transfer ink sheet used in a thermal transfer printer or the like built in a facsimile. Such a thermal transfer ink sheet is usually a band having a print width, for example, the same width as A4 size recording paper. FIG. 3 shows the plastic core of the present invention for winding such a band-shaped ink sheet. The core shown in FIG. 1 has a cylindrical core body 1. The length of the core body 1 is slightly larger than the width of the ink sheet to be wound, and the diameter is usually about 15 to 30 mm. The ink sheet take-up area 2 is provided substantially at the center of the core body 1, and the band-shaped ink sheet is wound thereon. Ring-shaped projections 3 are provided on both edges of the ink sheet winding area. Each ring-shaped projection 3 has, for example, a triangular cross-section, and a height measured from the surface of the core body 1 is 0.05 to
It is about 0.30 mm. Note that the both edges in the ink sheet take-up area are a relative concept that refers to a portion near the end of the area where the image is not affected. % Or less.

Shafts 4 for rotatably supporting the core body are integrally provided at both ends of the core body 1, and a gear 5 for further rotating the core body is provided on one shaft part. It is provided integrally. The plastic core shown in FIG. 3 has a shaft portion and a gear integrally provided, and as described above, the motivation that led to the present invention overcomes the problems of such an integrated plastic core. However, the plastic core of the present invention is not necessarily limited to such an integral type, and may be of a type in which a shaft portion and a gear are attached to the core body as separate members. This is because it is within the scope of the present invention as long as it can effectively prevent the sheet roll from falling off, which is a problem unique to the plastic core.

In the core shown in FIG. 3, the projections 3 have, for example, a ring shape with a triangular cross section. Various shapes can be used, such as a double ring-shaped one arranged side by side or a round head-shaped one described above arranged in a plurality in the circumferential direction of the core body. FIG. 4 and FIG. 5 are cross-sectional views schematically showing a state in which the wound sheet expands when a ring-shaped projection and a round head-shaped projection having a triangular cross section are provided. As shown in these figures, if there is a projection, the sheet is swollen and wound, so that the sheet roll is difficult to move in the direction indicated by the arrow in the drawing, that is, in the direction toward the projection, and such a projection is formed on both edges Since the sheet roll is provided, it is possible to effectively prevent the sheet roll from falling off in any direction.

The plastic core of the present invention is characterized in that it has projections at both edges in the sheet winding area, and the presence of the projections allows the sheet to be formed without relying on friction between the core surface and the inner surface of the sheet roll. The roll is effectively prevented from falling off. Therefore, although it is not generally necessary to perform unevenness on the core surface, it is not excluded to perform unevenness.

The plastic core of the present invention comprises polyethylene, polypropylene, polyvinyl chloride, ABS resin, A
It can be manufactured with a commonly used molding resin such as S resin. When the shaft and the gear are provided integrally, a certain mechanical strength is required, and therefore, it is preferable to use one having relatively high strength. Although it is not always preferable from the viewpoint of resources and the environment to discard the cores without reusing them, if such a possibility exists, harmful substances such as dioxins may be used during incineration. The use of chlorine-containing plastics, such as polyvinyl chloride, which may cause cracks, should be avoided.

[Brief description of the drawings]

FIG. 1 shows a replacement thermal transfer ink sheet including a delivery roll and a winding core.

FIG. 2 shows a core of a type in which plastic caps are fitted to both ends of a paper tube.

FIG. 3 shows a preferred example of the plastic core of the present invention.

FIG. 4 shows a relationship between a projection having a triangular cross section and a sheet wound thereon.

FIG. 5 shows a relationship between a round head-shaped protrusion and a sheet wound thereon.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Core main body 2 Sheet winding area 3 Projection 4 Shaft part 5 Gear 11 Sending-out roll 12 Winding core 21 Plastic cap formed with a shaft part and gear 22 Plastic cap formed with a shaft part 23 Paper tube

Claims (7)

[Claims] 1. A plastic core for winding a belt-shaped sheet into a roll, comprising a sheet winding area substantially at the center of a cylindrical core body, and having both edges in the sheet winding area. A plastic core having projections formed thereon. 2. The plastic core according to claim 1, wherein shaft portions for rotatably supporting the core body are provided integrally with the core body at both ends of the core body. 3. The plastic core according to claim 2, wherein at least one of said shaft portions is provided with a gear for driving said core body to rotate. 4. The projection according to claim 1, wherein said projection is a ring-shaped projection.
3. The plastic core according to any one of 3. 5. The plastic core according to claim 4, wherein said projection is a double ring-shaped projection. 6. The height of the ring-shaped projection is 0.05 to 0.5.
The plastic core according to claim 4 or 5, which is 30 mm. 7. The projection according to claim 1, wherein said projection is a round head-shaped projection.
The plastic core according to any one of the above.