Printing – Stenciling – Rotary machines
Reexamination Certificate
2003-10-03
2004-09-14
Hirshfeld, Andrew H. (Department: 2854)
Printing
Stenciling
Rotary machines
C101S116000
Reexamination Certificate
active
06789472
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a stencil printing machine which conveys a print medium while pressing the print medium to a drum on which a stencil sheet is mounted, and transfers ink oozing from perforations of the stencil sheet onto the print medium.
2. Description of Related Art
Printing method of a conventional stencil printing machine include an inner press printing method (refer to Japanese Patent Laid-Open Publication No. 7-132675) and an outer press printing method (refer to Japanese Patent Laid-Open Publication No. 2001-246828).
Brief description of the inner press printing method is as follows. As shown in
FIG. 1
, the conventional stencil printing machine with the inner press printing method has a drum
100
and a paper cylinder
101
, which are rotatably provided and placed so that the outer peripheral surfaces thereof are partially close to each other. The outer peripheral surface of the drum
100
is provided with a sheet clamping portion
100
a
which clamps an end of a stencil sheet
104
, and the outer peripheral wall thereof apart form the sheet clamping portion
100
a
is flexible and formed by an ink permeable screen
102
.
An ink supply mechanism
105
is provided inside the drum
100
. As shown in
FIG. 2
, this ink supply mechanism
105
has an inner press roller
106
which is an ink supply roller and is rotatably provided in a roller support member
107
. The inner press roller
106
is constructed to be movable between a press position and a holding position. At the press position, a force is applied to the roller support member
107
in a direction shown by an arrow a in
FIG. 2
so that the inner press roller
106
presses the inner peripheral surface of a screen
102
. At the holding position, the roller support member
107
is rotated in a direction shown by an arrow b in
FIG. 2
so that the inner press roller
106
is spaced apart from the inner peripheral surface of the screen
102
. The inner press roller
106
is located in the press position while print paper
111
passes and comes to the holding position during the rest of the time. The inner press roller
106
also has a function to allow printing pressure to act on the inner peripheral surface of the screen
102
.
Further, the roller support member
107
is rotatably supported about a support axis
108
serving as a center and provided with a doctor roller
109
and a driving rod
110
. The doctor roller
109
is cylindrical and fixed by the roller support member
107
in the vicinity of the inner press roller
106
. The driving rod
110
is rotatably supported by the roller support member
107
and placed in an upper space formed by the outer peripheral surfaces of the inner press roller
106
and the doctor roller
109
on the sides close each other. Ink
103
is supplied to this upper space from an unillustrated ink supply unit.
Next, the outline of a printing operation will be sequentially described. The stencil sheet
104
with a perforation image formed therein is mounted on the outer peripheral surface of the screen
102
. Then, in a printing mode, the drum
100
and the paper cylinder
101
are rotated in synchronization with each other in a direction shown by an arrow in FIG.
1
. Thereafter, the print paper
111
is fed between the drum
100
and the paper cylinder
101
.
Once the print paper
111
is fed, the inner press roller
106
presses the screen
102
and rotates following the drum
100
while pressing the screen
102
. The ink
103
that has passed through the gap between the doctor roller
109
and the inner press roller
106
is applied on the outer peripheral surface of the inner press roller
106
, and the applied ink
103
is sequentially supplied onto the inner surface of the screen
102
by the rotation of the inner press roller
106
.
Further, when the inner press roller
106
presses the screen
102
, the screen
102
stretches out toward the outer periphery thereof by the pressure and comes into contact with the paper cylinder
101
under the pressure. Then, the print paper
111
that has been conveyed between the drum
100
and the paper cylinder
101
is conveyed between the inner press roller
106
and the paper cylinder
101
while being in contact with and pressed by the screen
102
and the stencil sheet
104
. Due to this contact and pressure force, the ink
103
on the screen
102
is transferred onto the print paper
111
from the perforations of the stencil sheet
104
, and thereby an ink image is printed on the print paper
111
.
Brief description of the outer press printing method is as follows. As shown in
FIG. 3
, the conventional stencil printing machine with the outer press printing method has a drum
120
. On the outer peripheral surface of the drum
120
, a stencil sheet clamping portion
120
a
which clamps an end of the stencil sheet
104
is provided, and the outer peripheral wall
120
b
of the drum
120
apart from the stencil sheet clamping portion
120
a
is formed by a perforated ink penetratable member (ink permeable member).
An ink supply mechanism
125
is provided inside the drum
120
. This ink supply system
125
has a rotatably supported squeegee roller
126
and a doctor roller
127
placed adjacent to this squeegee roller
126
. Ink
128
is stored in an outer peripheral space surrounded by the squeegee roller
126
and the doctor roller
127
. The ink
128
applied on the outer periphery of the rotating squeegee roller
126
passes through a gap between the squeegee roller
126
and the doctor roller
127
. Thus, only the ink
128
with a predetermined thickness is applied on the squeegee roller
126
, and the ink
128
having this predetermined thickness is supplied on the inner surface of the outer peripheral wall
120
b
of the drum
120
.
Further, a pressure roller
130
is provided at a position facing the squeegee roller
126
and outside the drum
120
. The pressure roller
130
is constructed to be able to move between a press position where the pressure roller
130
presses the outer peripheral wall
120
b
of the drum
120
and a holding position where the pressure roller
130
is spaced apart from the outer peripheral wall
120
b
of the drum
120
. The pressure roller
130
comes to the press position while the print paper
111
passes and to the holding position during the rest of the time. The squeegee roller
126
is secured to a support portion which rotatably supports the outer peripheral wall
120
b
of the drum
120
. There is a clearance between the outer peripheral surface of the squeegee roller
126
and the inner peripheral surface of the outer peripheral wall
120
b
of the drum
120
in the state where the drum
120
is not pressed by the pressure roller
130
. When the outer peripheral wall
120
b
of the drum
120
is pressed by the pressure roller
130
, the outer peripheral wall
120
b
of the drum
120
bends so that the inner peripheral surface of the outer peripheral wall
120
b
of the drum
120
comes into contact with the outer peripheral surface of the squeegee roller
126
.
Next, the outline of a printing operation of the outer press printing method will be sequentially described. The stencil sheet
104
with a perforation image formed therein is mounted on the outer peripheral surface of the outer peripheral wall
120
b
of the drum. Then, in a printing mode, the outer peripheral wall
120
b
of the drum
120
is rotated in a direction shown by an arrow in
FIG. 3
, and the print paper
111
is fed between the drum
120
and the pressure roller
130
.
Once the print paper
111
is fed, the pressure roller
130
presses the outer peripheral wall
120
b
of the drum
120
, and the outer peripheral wall
120
b
is bent toward the inner periphery thereof. Due to this displacement, the outer peripheral wall
120
b
presses the squeegee roller
126
, and the squeegee roller
126
rotates following the drum
120
. The ink
128
that has passed through the gap between the doctor roller
127
and the squeegee roller
126
is applied on th
Naitou Taku
Nakamura Akira
Shibahara Takuya
Berkowitz Marvin C.
Culler Jill E.
Nath & Associates PLLC
Riso Kagaku Corporation
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