JP2975462B2 - Drum type printing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drum type printing apparatus such as a thermal transfer printer or a facsimile which prints and scans a sheet with clamp claws.

[0002]

2. Description of the Related Art As shown in FIG. 3, a thermal printer used as a drum type printing apparatus has a paper feed roller 1, a paper discharge roller 2, and a motor 4 arranged at required intervals.
And a timing belt 5 wrapped between the rollers 1, 2, 3 and a printing drum (platen drum) 6.
Of paper 7 inserted from one of the paper feed rollers
With the clamp claw 8 on the outer peripheral portion of the printing drum 6.
At the home position A, the paper 7 is moved by rotating the printing drum 6 in the counterclockwise direction in the figure while the paper 7 is wound around the drum 6, and supplied when passing through the thermal head 9. The image is transferred to the paper 7 by heating the ink sheet 11 supplied from the roll 10 with the thermal head 9 according to the print information. When the leading end of the printed paper 7 arrives at the discharge position B, The clamp by the clamp claw 8 is released and the paper is discharged from the paper discharge roller 2. On the other hand, the ink sheet 11 used for printing by the thermal head 9 is taken up by the take-up roll 1.
2 to wind it up.

Reference numeral 13 denotes a paper press roller for pressing the paper 7 against the print drum 6, reference numeral 14 denotes a press release solenoid, and reference numeral 15 denotes a drum rotation motor.

In the case of a color printer adopting a thermal transfer system such as the above-described thermal printer, multi-colors are expressed by repeated overlapping transfer of three colors (Y (yellow) → M (magenta) → C (cyan)). The positional accuracy of each color dot is required. For this reason, the printing drum 6 is a large-diameter drum (for example, having a diameter of 105 mm so that A4 paper can be wound), and the paper
Is fixed so that print scanning without paper misalignment is performed.

As shown in FIG. 4, for example, the thermal head 9 has a common electrode 16, an individual electrode 17, a resistance heating element 18 connected to both electrodes, and the like. Layer 19). The portion of the protective layer 19 that covers the heating element 18 protrudes.
The heating element 18 is selectively heated while being pressed against the printing drum 6 via the, so that the above-described printing is performed.

Here, conventionally, stainless steel (SUS) for a leaf spring has been used as a material of the clamp claw 8. That is, a conductive material having a higher hardness and a higher hardness than the protective layer 19 was used as the clamp claw.

By the way, in this type of printer, the thermal head 9 is displaced from the broken line position to the solid line position at the position C where the clamp claw 8 which clamps the leading end of the sheet 7 shown in FIG. , Is pressed against the print drum 6 via the ink sheet 11 and the paper 7.

Then, printing is started at the C position. In order to minimize the printing margin at the start of printing, after the clamp claw 8 has passed through the printing section 20, It is necessary to press the thermal head 9 and start printing in as short a time as possible. That is, it is necessary to press the thermal head and start printing at a position where the clamp claw 8 comes into contact with the protective layer protrusion 19A (FIG. 3) or not (see FIG. 4).

When the thermal head is pressed in such a manner, if the rotation of the printing drum 6 causes “unevenness”, the clamp claw 8 is moved to the protective layer projecting portion at the moment when the thermal head 9 is pressed against the printing drum 6. Touches 19A,
The resistive heating element 18 and the common electrode 16 are exposed by breaking through the protective layer protrusion 19A formed thinly in a film shape.

After the leading end of the paper 7 wound around the print drum 6 strikes the clamp claw 8 at the portion A, the clamp claw 8 closes. The clampability is further ensured. Therefore, if a little extra paper is fed after the impact, the clamp claw 8 may be closed with "wrinkles" occurring at the leading end of the paper. When such a situation occurs, the clamp claw 8 becomes higher on the print drum 6 than the normal position. Even in such a case, the clamp claw 8
May come into contact with the protection layer protrusion 19A, and the protection layer protrusion 1
It breaks through 9A.

In such a state, the metal clamp claws 8 may come into contact with the common electrode 16 (FIG. 4), causing a power supply trouble or the like, making printing and recording impossible. In a recording apparatus in which the thermal head 9 is separated from the print drum 6 with a predetermined gap when the clamp claw 8 comes directly under the protective layer protrusion 19A,
When the thermal head 9 does not separate from the printing drum 6 for some reason, the clamp claw 8 is moved to the protection layer projecting portion 19A.
And the protective layer protruding portion 19A is pierced, and the common electrode 16 and the like are exposed, causing the same trouble.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to make it difficult for a protective layer to be broken by a clamp claw,
It is an object of the present invention to provide a drum-type printing apparatus in which a power supply trouble or the like does not occur even if it is broken and a common electrode or the like is exposed to the outside.

[0013]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a printing drum and a clamp claw provided on the printing drum and having a claw for clamping an end of a sheet wound around the printing drum. In a drum type printing apparatus having a heating element and a thermal head in which a protective layer portion covering the heating element is pressed against a printing drum, at least the claw portion of the clamp claw has a hardness lower than that of the protection layer. We propose a drum type printing device made of a synthetic resin material having elasticity and electrical insulation.

It is effective if the paper contact side portion of the claw portion has a minute uneven shape.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a drum type printing apparatus according to this embodiment also has a printing drum 6 and a claw portion provided on the printing drum 6 for clamping an end of a sheet 7 wound around the printing drum 6. 1, a thermal head (not shown in FIG. 1) is provided with a heating element, and a protective layer covering the heating element is pressed against the printing drum (FIG. 4). The printing drum 6 is formed by integrally laminating a rubber layer 22 around a drum core 21. The clamp claw 28 is swingable around the fulcrum 23, and its claw 28 a is pressed against the rubber layer 22 via the leading end of the paper 7 by the force of the spring 24. Thus, the leading end of the sheet 7 is clamped. At this time, the claw portion 28a is elastically deformed, and the clamping action of the tip portion is ensured.

The drum type printing apparatus of this embodiment is characterized in that the clamp claws 28 are made of a synthetic resin material having a lower hardness than the protective layer 19 (FIG. 4) and having elasticity and electrical insulation. I do.

For example, the clamp claw 28
(Polyamide), POM (Polyacetal), PC (Polycarbonate) and the like.

The protection layer 19 shown in FIG. 4 has a hardness of Hv 1800 to 2 when the material type is, for example, SiN.
It is about 000. The clamp claw 28 is made of a synthetic resin material having a lower hardness than the above. By using the clamp claws of such a kind, it is basically eliminated that the resistance heating element 18 and the common electrode 16 are exposed to the outside by breaking through the protection layer projection 19A.

Even if the clamp claw 28 breaks through the protective layer protrusion 19A, a short circuit occurs between the clamp claw 28 and the common electrode 16 because the clamp claw itself is an insulating material. This does not occur, and the power supply is not damaged.

It should be noted that only the clamp claw 28a may be of the above-described material type, and may be configured to be fixed to the clamp claw body with a screw, an adhesive, or the like. The main body may be made of metal. However, if the entire clamp claw 28 is made of the above-described material and is integrally molded, the configuration of this kind of clamp claw can be simplified, and the cost is also advantageous. As described above, at least the claw portion 28 of the clamp claw 28 is used.
a is made of a synthetic resin material having a lower hardness than the protective layer and having elasticity and electric insulation.

As described above, the leading end of the paper 7 is firmly clamped by the elasticity of the claw 28a itself. The paper contact side portion of the claw 28a is shown in FIG. In addition, the minute projections and depressions cause the sharp projections to bite into the paper. Thereby, the grip effect can be further enhanced.

[0022]

According to the drum type printing apparatus of the first aspect of the present invention, the head protective layer is less likely to be broken, so that the head function can be maintained satisfactorily and stably. Also, even if the protective layer is broken, it is possible to prevent a short circuit between the electrode and the protective layer,
Thereby, it is possible to prevent the power supply from being damaged.

According to the drum type printing apparatus of the second aspect, the effect of clamping the leading edge of the paper can be further enhanced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a printing drum unit provided in a drum type printing apparatus according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of another example of a clamp claw.

FIG. 3 is a schematic configuration diagram of a thermal printer used in the description of the related art.

FIG. 4 is a cross-sectional view of a printing component used for explaining a problem of the conventional example.

[Explanation of symbols]

 6 Printing Drum 7 Paper 18 Heating Element 19A Protective Layer 28 Clamp Claw 28a Claw

Claims (2)

(57) [Claims] [1 claim: a print drum, is provided on the printing drum, the clamp jaws having a claw portion for clamping the edge of the sheet of paper wound around the indicia shaped drum, comprising a heating element, the onset <br/> Netsutai And a thermal head in which a protective layer portion covering the printing drum is pressed against the printing drum, wherein at least the claw portion of the clamp claw is made of a synthetic resin material having lower hardness, elasticity and electrical insulation than the protection layer. A drum type printing apparatus characterized by comprising: Wherein the the paper contact side portion of the claw portion, a drum type printing apparatus according to claim 1 in which the fine irregularities.