Printing – Stenciling – Rotary machines
Reexamination Certificate
2000-09-27
2003-01-14
Evanisko, Leslie J. (Department: 2854)
Printing
Stenciling
Rotary machines
C101S415100
Reexamination Certificate
active
06505551
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a stencil printing machine having a cylindrical printing drum which has a stencil sheet wound around an outer peripheral surface thereof and is rotatably driven.
2. Description of the Related Art
FIG. 16
is a cross-sectional view showing a basic structure of a conventional stencil printing machine.
The stencil printing machine includes a printing drum
100
. The printing drum
100
has a base body
103
which is comprised of a pair of circular plate members
101
arranged coaxially on a common central axis and a stencil clamping base
102
which connects a pair of circular plate members
101
. A gear
104
is fixedly and coaxially mounted on the base body
103
. The gear
104
is meshed with a drive gear not shown in the drawing. Upon rotation of the drive gear, the base body
103
is rotatably driven about the central axis.
An ink passing and flexible ink passing member
105
is wound around the base body
103
. The ink passing member
105
has one end thereof fixedly secured to the stencil clamping base
102
of the base body
103
. The ink passing member
105
is wound around outer peripheral surfaces of the circular plate members
101
. The ink passing member
105
has the other end thereof elastically mounted on the stencil clamping base
102
by means of a spring
106
. Accordingly, when the ink passing member
105
is pushed from the inside, the ink passing member
105
is elastically deformed outwardly. The stencil clamping base
102
is provided with clamp means
107
. A perforated stencil sheet has a leading end thereof fixedly secured to the stencil clamping base
102
by means of clamp means
107
and is wound around an outer peripheral surface of the ink passing member
105
.
In the inside of the printing drum
100
, a squeezing roller
110
is elevatably mounted. In synchronous with the rotation of the printing drum
100
, the squeezing roller
110
is elevated at a given timing and presses the ink passing member
105
outwardly. The squeezing roller
110
is rotatably driven in the same direction as the printing drum
100
in an interlocking manner with the printing drum
100
by means of the drive gear
104
of the printing drum
100
, an intermediate gear
111
and a gear
112
of the squeezing roller
110
. Ink is supplied to the inside of the printing drum
100
by way of an ink supply pipe
113
and a constant amount of ink is supplied to a peripheral surface of the squeezing roller
110
by means of a doctor roller
114
which is arranged against the squeezing roller
110
at a given interval.
Although not shown in the drawing, a pressure drum having a diameter approximately equal to that of the printing drum
100
is disposed below the printing drum
100
. The axis of rotation of the pressure drum is parallel to the central axis of the printing drum
100
. In the non-printing state, a minute clearance is formed between the printing drum
100
and the pressure drum. The pressure drum is rotatably driven in synchronous with the rotation of the printing drum
100
but in the opposite direction. A printing paper is fed between the printing drum
100
and the pressure drum. The squeezing roller
110
is lowered at a given timing so as to push the ink passing member
105
outwardly. The ink passing member
105
which is deformed outwardly and a stencil sheet clamp the printing paper between these members and the pressure drum. The printing paper is conveyed while being clamped between the deformed printing drum
100
and the pressure drum. During the conveyance, ink supplied to the inner peripheral surface of the ink passing member
105
is transferred to the printing paper through the ink passing member
105
and a perforated portion of the stencil sheet thus forming an image.
An image of an original to be printed is read by an image reader
200
and is supplied to a stencil making section
300
as image signals.
The stencil making section
300
includes a platen roller
301
and a thermal head
302
. The stencil sheet M having a roll shape is clamped between the platen roller
301
and the thermal head
302
and is conveyed. During conveyance, the thermal head
302
is driven by an image signal fed from the image reader
200
and generates heat and forms a perforated image in the stencil sheet M. The stencil sheet M in which the perforated image is formed is conveyed to a position in the vicinity of the printing drum
100
by means of the platen roller
301
and feed rollers
303
. The stencil sheet M has a leading end portion thereof fixedly secured onto the stencil clamping base
102
by means of the clamp means
107
and is wound around the outer peripheral surface of the printing drum
100
along with the rotation of the printing drum
100
in the counterclockwise direction in the drawing. When the stencil sheet M is wound around the printing drum
100
by a given dimension corresponding to one sheet, the stencil sheet M is cut by a cutter
304
. This cut portion disposed at the side opposite to the leading end portion of the stencil sheet M which is fixedly secured to the clamp means
107
constitutes a trailing end portion of the stencil sheet M.
Thereafter, the printing is performed. After printing, the used stencil sheet M is peeled off from the printing drum
100
and is removed. With the clamp means
107
in the opened state, the printing drum
100
is rotated. The leading end portion of the stencil sheet M released from the clamp means
107
is clamped between a pair of stencil discharge rollers
401
and is stacked in a stencil discharge section
400
including a stencil discharge box by driving the stencil discharge rollers
401
. At the time of discharging the used stencil sheet M, ink remaining on the used stencil sheet M is adhered to the stencil discharge rollers
401
.
In the above-mentioned state, when the stencil making and the printing are performed based on a new image, at the time of winding the newly perforated stencil sheet M which is fed from the feed rollers
303
around the printing drum
100
and printing, there has been a trouble that the trailing end portion which is not fixedly secured by the clamp means
107
is lifted and comes into contact with the stencil discharge roller
401
or the like so that ink is adhered to it. Further, it gives rise to several problems including a problem that ink adhered to the trailing end portion of the stencil sheet M is transferred to the printing member thus staining the printing paper.
Further, in the stencil printing machine, in case of performing a duplex printing, as shown in
FIG. 17
, for example, it is considered to prepare two rotatable cylindrical printing drums
501
,
502
which have outer peripheral surfaces thereof wound around by stencil sheets M. These printing drums
501
,
502
have axes of rotation which are disposed parallel to each other. Further, in the insides of respective printing drums
501
,
502
, squeezing rollers
503
,
504
which supply ink to the outer peripheries of the printing drums
501
,
502
are disposed. Subsequently, a printing paper P is fed between respective printing drums
501
,
502
and then the printing paper P is nipped between the outer peripheral surfaces of the printing drums
501
,
502
so as to transfer the ink which passes through the stencil sheets M onto the printing paper P thus completing the duplex printing.
Further, for winding the stencil sheets M around the outer peripheral surfaces of the printing drums, the printing drums
501
,
502
are respectively provided with stopper mechanisms for clamping leading end portions of the conveyed stencil sheets M to portions of the outer peripheral surfaces of the printing drums
501
,
502
. These stopper mechanisms include clamp plates
505
,
506
which can be opened and closed. The clamp plates
505
,
506
clamp the leading end portions of the stencil sheets M by closing operations and release the leading end portions of the stencil sheets M by opening operations.
Further, the above-mentioned stoppe
Kawabe Takao
Takahashi Yasuhiro
Evanisko Leslie J.
Riso Kagaku Corporation
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