Thermal printer

Details Thermal printer Thermal printer

1999-10-20

2001-04-24

Le, N. (Department: 2861)

Incremental printing of symbolic information

Thermal marking apparatus or processes

Record receiver driving means

Reexamination Certificate

active

06222576

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thermal printer, and more particularly to a thermal printer in which a recording paper is fed between a thermal head and a platen.
2. Description of the Related Art
There is a color thermal printer in which a color thermosensitive recording paper is used to obtain a full-color print. The color thermosensitive recording paper has a plurality of thermosensitive coloring layers stacked on a support member. Thermal recording is performed for the respective thermosensitive coloring layers of the recording paper by means of a thermal head in a frame sequential manner. In such a color thermal printer, a color thermosensitive recording paper is fed between a thermal head and a platen, and one of the thermal head and the platen is moved toward the other thereof to nip the recording paper. After that, thermal recording is performed for the recording paper by heating the thermal head.
Japanese Patent Laid-Open Publication No. 10-217518 discloses a color thermal printer of which size is reduced by projecting a part of a color thermosensitive recording paper to the outside of the printer at the time of printing. In this color thermal printer, a recording face of the recording paper is adapted to be directed downward so that a thermosensitive coloring layer of the recording paper is prevented from being fixed by the ambient light. For this, a thermal head is disposed under a conveyance passage of the recording paper. Further, a platen facing the thermal head and nipping the recording paper is disposed above the thermal head.
In conventional color thermal printers, if a color thermosensitive recording paper has a curling peculiarity, the recording paper abuts on a thermal head or a platen when the recording paper is fed between the thermal head and the platen. Thus, there arises a problem in that the recording paper is not properly forwarded between the thermal head and the platen. In a color thermal printer having a thermal head disposed under a conveyance passage, an upper face of the thermal head is provided with a heating element array comprising a plurality of heating elements. Due to this, jamming of the recording paper sometimes occurs because a leading edge of the recording paper forwarded between the thermal head and the platen is caught by the upper face of the thermal head. Otherwise, as to a seal-like color thermosensitive recording paper, a recording paper is peeled from a separation paper so that defect of printing, failure in conveyance and so forth are caused.
The above-mentioned problems may be solved by disposing a roll, which acts as feeding means for conveying the recording paper, at a position being higher than the thermal head. However, when the roller is disposed at the higher position than the thermal head, an abutting condition of the recording paper and the heating element array becomes worse. Therefore, there arises a problem in that a print image becomes unclear.
SUMMARY OF THE INVENTION
In view of the foregoing, it is a primary object of the present invention to provide a thermal printer in which a recording paper is properly fed between a thermal head and a platen.
It is a second object of the present invention to provide a thermal printer in which a leading edge of a recording paper is not damaged.
It is a third object of the present invention to provide a thermal printer in which jamming and failure conveyance of a recording paper are prevented from occurring.
In order to achieve the above and other objects, the thermal printer according to the present invention comprises a guide member disposed between a thermal head and a paper feeding member.
The guide member is movable between a guide position where the guide member projects into a conveyance passage of a recording paper, and an evacuation position where the guide member is evacuated from the conveyance passage of the recording paper. When the recording paper is fed, the guide member is set at the guide position to properly forward the recording paper between the thermal head and a platen. When the recording paper is nipped by the thermal head and the platen, the guide member is set at the evacuation position.
The guide member is moved between the guide position and the evacuation position in association with operations in that the recording paper is nipped by the thermal head and the platen, and in that the recording paper is released from being nipped.
The guide member is urged by a spring toward the guide position. When the recording paper is nipped by the thermal head and the platen, the guide member is pushed and moved to the evacuation position against the urging force of the spring. When the recording paper is released from being nipped, pushing the guide member is taken away so that the guide member is moved to the guide position by the urging force of the spring.
The guide member has a plate-like shape or is constituted of a rotatable roller. In the case of the plate-shaped guide member, the guide member is integrally formed with the spring by using a plastic having elasticity.
Nipping the recording paper with the thermal head and the platen is performed after the guide member has been moved to the evacuation position.


REFERENCES:
patent: 6078345 (2000-06-01), Yamakawa et al.
patent: 6089487 (2000-07-01), Imai et al.
patent: 10-217518 (1998-08-01), None

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