Cutting – Means to drive or to guide tool – With simple rectilinear reciprocating motion only
Reexamination Certificate
2002-09-17
2004-09-07
Ashley, Boyer D. (Department: 3724)
Cutting
Means to drive or to guide tool
With simple rectilinear reciprocating motion only
C083S628000, C083S629000, C083S636000, C083S697000, C083S694000, C074S437000, C192S048920, C400S621000
Reexamination Certificate
active
06786125
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cutter device for a printer for cutting paper after printing.
2. Description of the Related Art
Thermal printers have been widely used as output devices for facsimile machines, POS systems and the like. In many cases, a roll of heat-sensitive paper is used as the recording paper.
Some of these printers use a roll of paper and are equipped with a cutter device for automatically cutting the recording paper after printing into an appropriate length.
The cutter device is equipped with a stationary blade and a movable blade, and the movable blade is driven with a predetermined timing using a dedicated drive source or a printer drive source to cut the recording paper after printing.
The movable blade is of two types: a type in which a round blade rolls along the stationary blade in a direction perpendicular to the recording paper conveying direction; and a so-called guillotine-type in which a plate-like blade with a clearance angle at the end moves toward and away from the stationary blade.
FIG. 6
shows an example of the guillotine type cutter device.
FIG. 6
is an exploded perspective view showing an example of the construction of a conventional guillotine type cutter device C
2
.
As shown in
FIG. 6
, there are provided five gears arranged on an upper plate
136
of a head support plate
116
: a gear (driving gear)
127
, and driven gears
128
,
129
,
130
, and
131
, and axles
127
a
,
128
a
,
129
a
,
130
a
, and
131
a
for rotatably mounting these gears to the upper plate
136
. These gears
127
,
128
,
129
,
130
, and
131
are arranged two-dimensionally along the upper plate
136
arranged parallel to the paper feeding direction X. Reference numeral
113
indicates a platen roller for conveying the recording paper (not shown) in the X-direction.
In a cutter drive mechanism
120
, power transmitted through a bevel gear
126
is transmitted successively by way of the gear (driving gear)
127
and the driven gears
128
,
129
,
130
,
131
. The construction of the cutter drive mechanism
120
is such that the gears
128
and
1431
move in synchronism with a gear ration of one-to-one. At positions off the rotation centers of the gears
128
and
131
, drive pins
128
b
and
131
b
protrude downwardly for driving the movable blade
112
, causing a slide plate
117
to slide in the paper feeding direction X. The slide plate
117
has two guide grooves
117
a
and
117
b
in the form of elongated round holes extending in the direction perpendicular to the paper feeding direction X. At the time of assembly, the drive pins
128
b
and
131
b
are inserted into the guide grooves
117
a
and
117
b
under the upper plate
136
fixed to the upper surface of the support plate
136
fixed to the upper surface of the support plate
116
(on the thermal head side) so as to allow movement (sliding) in the paper feeding direction X with the cutter drive mechanism
120
therebetween. Thus, when the gears
127
through
131
rotate, the drive pins
128
b
and
131
b
rotate, and, with this rotation, the slide plate
117
reciprocates in a direction parallel to the paper feeding direction X. As a result the movable blade
112
fixed to the slide plate
117
reciprocates between the home position H and the cutting position C. In
FIG. 7
, the movable blade
112
is at the home position H, and in
FIG. 8
, it is at the cutting position C.
FIG. 9
shows the construction of the cutter drive mechanism
120
.
As shown in
FIG. 9
, on the gear
128
of the cutter drive mechanism
120
, there is formed a clutch portion
141
with a part of its teeth cut away; further, due to an engagement pin
145
provided at a position off the rotation center, the gear
128
is pressurized by a torsion spring
139
in a predetermined direction, which, in this example, is counterclockwise as seen from above the cutter drive mechanism
120
.
The gear (driven gear)
128
and the gear (driving gear)
127
form a one-revolution (single-revolution) clutch mechanism
140
. In the condition in which the clutch portion
141
is in contact with the gear
127
, the gear
128
is pressurized counterclockwise by a force F
2
, so that, if the gear
127
rotates counterclockwise, there is no gear meshing, and no power is transmitted.
When the gear
127
rotates clockwise, it is engaged with the gear
128
, and power is transmitted. And when the gear
127
rotates clockwise and the gear
128
makes one revolution, the movable blade
112
makes one reciprocation between the home position H and the cutting position C. Thereafter, when the gear
127
rotates counterclockwise, the clutch
141
is restored, while in contact with the gear
127
, to the angle at which it is pressurized by the spring
139
.
Thus, the angle of the gear
128
when printing is being performed through counterclockwise rotation of the gear
127
is always kept at a fixed level, and, during printing, the movable blade
112
is set at the home position H without fail.
By using the one-revolution mechanism
140
thus constructed, it is possible to reliably maintain the movable blade
112
at the home position without using any optical sensor or limit switch, making it advantageously possible to provide a cutter device C
2
of a simple construction and high positional accuracy.
In the one-revolution clutch mechanism
140
provided in the cutter drive mechanism
120
of the cutter device C
2
shown in
FIGS. 6 through 9
, when the gear
127
rotates counterclockwise, it idles with its teeth flicking clockwise the edge portion of the cutout portion
141
of the gear
128
, so that no power is transmitted to the gear
128
, and the cutter device is placed in the printable state in which the movable blade
112
is kept on standby at the home position H. The torsion spring
139
which engages in this state with the engagement pin
145
of the gear
128
to impart an urging force in the direction F
2
is relatively large, and its resilient force is strong, so that there is a great crackling noise when the gear
128
is flicked, which constitutes a noise factor in the printer operation.
Further, the vibration when the gear
128
is flicked is relatively great, and the vibration generated between the gear (driving gear)
127
and the gear (driven gear)
128
during printing may be transmitted to the entire printer through the other driven gears
129
,
130
,
131
, etc., thereby adversely affecting the printing quality.
SUMMARY OF THE INVENTION
This invention has been made with a view to solving the above-mentioned problems in the prior art. It is an object of this invention to provide a cutter device for a printer in which in a printing state in which a movable blade is on standby for movement, it is possible to reduce a flicking noise generated between gears and to restrain vibrations generated thereby.
In order to achieve the above-mentioned object, according to the present invention, there is provided a cutter device for a printer equipped with a movable blade (
17
) and a stationary blade (
300
) for cutting at a predetermined position recording paper which has undergone printing by a printing means, the cutter device including:
a cutter drive mechanism (
20
) for causing the movable blade to advance and retreat with respect to the stationary blade,
the cutter drive mechanism being equipped with a rotation mechanism which causes, through one rotation of a driven gear (
28
) connected to the movable blade, the movable blade to make one reciprocation between a home position (H) spaced apart from the stationary blade by a predetermined distance and a cutting position (c) where it cuts the recording paper through cooperation with the stationary blade,
the rotation mechanism being connected to a one-way clutch mechanism (
40
) connected to a driving means capable of normal and reverse rotation and adapted to rotate a platen roller (
13
) in the paper feeding direction when the driving means makes normal rotation and to drive the movable blade of the cutter when the driving m
Adams & Wilks
Ashley Boyer D.
SII P & S Inc.
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