Printing – Stenciling – Rotary machines
Reexamination Certificate
2001-05-18
2003-06-24
Yan, Ren (Department: 2854)
Printing
Stenciling
Rotary machines
C101S232000
Reexamination Certificate
active
06581514
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a print medium feed device for feeding a print medium to a press drum or the like and a stencil printing machine using such a print medium feed device and, more particularly, to a print medium feed device and a stencil printing machine adapted to transfer a print medium such as a print sheet in a feed path wherein an initial transfer angle of the print medium relative to a feed tray is remarkably different from a subsequent advancing angle of the print medium relative to the press drum.
Various researches and developments have been undertaken to provide an improved paper feed device for a stencil printing machine allowing to perform multi-colored print with plural printing drums, a typical example of which is disclosed in
FIG. 8
which shows a part of a structure of such a stencil printing machine. In
FIG. 8
, first and second printing drums
101
and
102
and a press drum
103
are rotatably supported in a frame body (not shown) such that the first and second printing drums
101
and
102
are located in close proximity to an outer periphery of the press drum
103
at positions angled at 90 degrees of a central angle of the press drum
103
. Outer circumferential peripheries of the respective first and second printing drums
101
and
102
carry thereon stencil clamping bases
101
a
and
102
a
, respectively, which support thereon sheet clamping segments
101
b
and
102
b
for clamping stencil sheets (not shown) onto the stencil clamping bases
101
a
and
102
a,
respectively.
Further, screens
105
are wound on the outer circumferential peripheries of the first and second printing drums
101
and
102
in a stretched state with the use of the stencil clamping bases
101
a
and
102
a
and springs
104
, with each of the screens
105
being formed of a mesh-shaped porous structure which allows printing ink to permeate. Inner press rollers
106
and
107
, which serve as ink supply rollers, respectively, are located inside the screens
105
of the first and second printing drums
101
and
102
, respectively, with the inner press rollers
106
and
107
being moveable between a wait position not to press the screens
105
and a press-contact position to press the screens
105
. During printing operation, the inner press rollers
106
and
107
are maintained in the press-contact position, in which the screens
105
are expanded outward. Also, it is arranged such that the screen
105
of the first printing drum
101
is supplied with printing ink in a first color by the inner press roller
106
and the screen
105
of the second printing drum
102
is supplied with printing ink in a second color by the inner press roller
107
. The outer circumferential periphery of the press drum
103
is provided with a print sheet clamping segment
109
, for clamping a leading edge of a print sheet (print paper)
108
, which clamps the leading edge of the print sheet
108
transferred from a paper feed device
110
and release the leading edge of the print sheet
108
at a position in the vicinity of an inlet portion of a sheet discharge section
111
.
The paper feed device
110
is constructed of a paper feed tray
112
on which a stack of print sheets
108
are located, a pair of primary paper feed rollers
113
,
113
which are held in press-contact with an uppermost print sheet
108
stacked on the paper feed tray
112
, a pair of secondary paper feed rollers
114
,
114
located downstream of the primary paper feed rollers
113
,
113
, and a pair of transfer guide members
115
,
115
which function to guide the print sheet
108
in a transfer path between the pair of secondary paper feed rollers
114
,
114
and the press drum
103
. Rotations of the primary paper feed rollers
113
,
113
allow only the uppermost print sheet
108
to be transferred from the paper feed tray
112
to the pair of secondary paper feed rollers
114
,
114
. The print sheet
108
is then transferred with rotations of the pair of secondary paper feed rollers
114
,
114
and is fed to the press drum
103
in synchronism with rotation thereof.
Now, the stencil printing machine thus arranged operates as follows. A leading edge of a first stencil sheet, which has been made on the basis of image data in a first color of an original is clamped with the sheet clamping segment
101
b
of the first printing drum
101
, and a leading edge of a second stencil sheet, which has been made on the basis of image data in a second color of the original, is clamped with the sheet clamping segment
102
b
of the second printing drum
102
, with the stencil sheets being mounted onto the outer circumferential peripheries of the respective screens
105
. Next, the first and second printing drums
101
and
102
and the press drum
103
are rotated in synchronism with one another in directions as shown by arrows in
FIG. 8
, thereby causing the print sheet
108
to be transferred between the first printing drum
101
and the press drum
103
from the paper feed device
110
.
The print sheet
108
thus transferred is clamped with the print sheet clamping segment
109
of the press drum
103
, allowing the print sheet to pass along the outer circumferential periphery of the press drum
103
between the first printing drum
101
and the press drum
103
. During this passing step of the print sheet
108
, the inner press roller
106
is brought into press-contact with the screen
105
of the first printing drum
101
which is consequently expanded outward, allowing printing ink to be transferred to the print sheet
108
to reproduce a desired image pattern with a first color through a perforated image area of the first stencil sheet. The print sheet
108
, which has passed between the first printing drum
101
and the press drum
103
, then passes between the second printing drum
102
and the press drum
103
. During this passing step of the print sheet a
108
, the inner press roller
107
is brought into press-contact with the screen
105
on the second printing drum
102
which is consequently expanded outward, allowing printing ink to be transferred to the print sheet
108
to reproduce a desired image pattern with a second color. As the sheet clamping segment
109
of the press drum
103
is rotated to a position near the inlet of the sheet discharge section
111
, the sheet clamping segment
109
is released, with the released print sheet
108
being discharged to the given discharge position by the sheet discharge section
111
. In this manner, two-color printing is completed.
Now, operation of the paper feed device
110
is described in detail. When the primary paper feed rollers
113
,
113
are rotated, only the uppermost print sheet
108
is transferred from the stack of the print sheets on the paper feed tray
112
until the leading edge of the print sheet
108
is introduced to a position between the secondary paper feed rollers
114
,
114
, at which position a further transfer of the print sheet
108
is stopped. Subsequently, the secondary paper feed rollers
114
,
114
are rotated in synchronism with rotation of the press drum
103
, allowing the print sheet
108
to be fed to the press drum
103
, while guided with a pair of transfer guide members
115
,
115
, at a prescribed advancing point and at a prescribed advancing angle. The print sheet
108
, thus transferred to the press drum
108
, is successively transferred therewith.
In the event the pair of secondary paper feed rollers
114
,
114
complete their transfer cycle, rotations of the secondary paper feed rollers
114
,
114
are interrupted and one of the paper feed rollers
114
,
114
is shifted to a disengagement position relative to the other paper feed roller. With such a shifting movement, the print sheet
108
is transferred without encountering with difficulties.
SUMMARY OF THE INVENTION
However, due to the further studies done by the inventor of the present invention, in a printing machine such as the machine discussed above, wherein two printing drums
101
,
102
are located r
Berkowitz Marvin C.
Nath Gary M.
Novick Harold L.
Riso Kagaku Corporation
Yan Ren
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