Typewriting machines – Typing by other than type-face or type-die – Thermal
Reexamination Certificate
1998-09-14
2001-08-21
Hilten, John S. (Department: 2854)
Typewriting machines
Typing by other than type-face or type-die
Thermal
C400S694000, C400S642000, C400S645500
Reexamination Certificate
active
06276848
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a small-sized line thermal printer used for a portable electronic device such as a receipt issuing machine.
BACKGROUND ART
Heretofore, a small-sized line thermal printer is widely used for a portable electronic device such as a receipt issuing machine.
As this type of thermal printer is required to be readily portable, a small-sized, light one is desired.
Therefore, heretofore, a body frame is made of metal such as a thin steel plate and a paper guide made of plastic for guiding recording paper to a printing part between a platen roller and a thermal head is installed as disclosed, for example, in Unexamined Japanese Patent Application No. Hei. 4-140175.
In such a thermal printer, a platen roller
104
and a head support part
103
are secured to a body frame
102
made of plastic as shown in
FIG. 6
, for example. Predetermined printing is executed on thermal recording paper by attaching a thermal head
130
on the side of the platen roller
104
of the head support part
103
so that thermal recording paper is held between the thermal head and the platen roller and by pressing the thermal head
130
attached to the head support part
103
on the platen roller
104
by a torsion coil spring
107
.
There is also another conventional thermal printer in which a body frame is formed integrally with a paper guide from plastic material such as polycarbonate.
However, in such conventional type thermal printers, there are the following problems:
That is, in the case of the above conventional type thermal printers, as the paper guide
121
is made of plastic material, a charge cannot be discharged from the paper guide if thermal recording paper
100
is electrified, and the thermal head
130
may be broken by a spark and others.
Further, as the paper guide
121
is also electrified, there is a problem that the thermal recording paper
100
cannot be guided to the vicinity of the thermal head
130
and the thermal recording paper is hard to insert.
As the platen roller
104
is arranged apart from the bottom of the printer in view of space for gears for driving the platen roller, the paper guide
121
cannot be formed as a part of the body frame
102
. Therefore, as the paper guide
121
is made of another member, the number of parts is increased and as a result, the cost is increased.
Even if the paper guide
121
is formed as a part of the body frame
102
, there is also a problem that it is difficult to increase an angle at which thermal recording paper
100
is wound on the platen roller
104
and precision in feeding paper is not satisfactory.
Furthermore, if the body frame is also made of plastic material as in the other conventional types, the frame must be formed relatively thick to enhance rigidity. As a result, miniaturization cannot be sufficiently achieved.
SUMMARY OF THE INVENTION
The present invention was made in view of the problems and difficulties accompanying the conventional thermal printers. Therefore, an object of the present invention is to provide a thermal printer capable of increasing an angle at which thermal recording paper is wound on a platen roller without generating static electricity.
Another object of the present invention is to provide a thermal printer that is small in size and light in weight, which requires the small numbers of parts and components.
A thermal printer according to the present invention includes a metallic body frame for supporting at least one of a thermal head and a platen roller for holding recording paper in a printing position and a paper guide for guiding the recording paper to the printing position. In the thermal printer of the invention, the paper guide at least in the vicinity of the printing position is integrated, meaning homogeneously formed so as to be a single part, with the body frame.
According to the above constitution, as the paper guide for guiding recording paper to the printing paper is integrated with the metallic body frame, static electricity is discharged via recording paper even if the recording paper is electrified and the paper guide is never electrified. As a result, as no spark is generated between the vicinity of a printing position of the paper guide and the thermal head, the paper guide can be arranged in the vicinity of the printing position and thermal recording paper can be readily and smoothly inserted.
In addition, as the paper guide is not made of plastic material in the case of the present invention, the thickness can be reduced, and as the paper guide is integrated with the body frame, the number of parts can be reduced and as a result, a small-sized, light and low-priced thermal printer can be obtained.
Also, in the case of the present invention, the paper guide in a position in which recording paper is inserted is integrated with the body frame, is bent upward approximately along the width of paper and is provided with a bend-raise portion on which recording paper is slid.
In this case, as static electricity generated on recording paper is discharged via the bend-raise portion by integrating the bend-raise portion which comes in contact with the recording paper with the frame, the carried recording paper can be prevented from being electrified, and any detrimental effect upon the thermal head by static electricity can be prevented.
As an angle at which recording paper is wound on the platen roller can be increased by the bend-raise portion and in addition, the area in which the paper guide and the recording paper are in contact is reduced by the bend-raise portion, a running load is not increased even if the recording paper is wet, the recording paper is smoothly run and high quality printing is enabled.
Further, in the case of the present invention, the paper guide is provided with a step relative to the bottom of the body frame along the direction of the width of recording paper so as to approach the platen roller.
According to the above constitution, the shape along the platen roller of the paper guide can be readily obtained without working so that the paper guide is large-sized, the bend-raise portion provided with desired height can be obtained and hereby, the paper guide high in rigidity and precision can be obtained.
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patent: 57-177755 (1982-11-01), None
patent: 60-105573-A (1985-06-01), None
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Kumagai Katsunari
Shimizu Manabu
Takizawa Hiroshi
Yamada Koji
Grohusky Leslie J.
Hilten John S.
Nixon & Vanderhye P.C.
Seiko Epson Corporation
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