Printing – Stenciling – Rotary machines
Reexamination Certificate
2000-11-21
2002-08-20
Funk, Stephen R. (Department: 2854)
Printing
Stenciling
Rotary machines
C271S273000
Reexamination Certificate
active
06435084
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a rotary type stencil printing machine. According to the rotary type stencil printing machine of the present invention, a print sheet is printed while being carried by being sandwiched between a printing drum and a back press roller. Further, the print sheet is carried while being pressed to the back press roller by a pinch roller after having been peeled off from the printing drum.
2. Description of the Related Art
FIG. 15
is a sectional view showing an example of a basic structure of a conventional rotary type stencil printing machine.
The stencil printing machine is provided with a printing drum
100
. The printing drum
100
is provided with a base member
103
comprising a pair of circular plate members
101
arranged coaxially on a common central axis line
104
and a stencil clamping base
102
for connecting the pair of circular plate members
101
. The base member
103
is fixed with a gear, not illustrated, coaxially with the central axis line
104
. The gear is in mesh with a drive gear, not illustrated. By rotation of the drive gear, the base member
103
is driven to rotate centering on the central axis line
104
.
A screen member
105
which is ink-permeable and flexible, is made to wrap on the base member
103
. One end portion of the screen member
105
is fixed to the stencil clamping base
102
of the base member
103
. The screen member
105
is made to wrap on outer peripheral surfaces of the circular plate members
101
. Other end portion of the screen member
105
is elastically attached to the stencil clamping base
102
via a spring, not illustrated. Therefore, the screen member
105
is elastically deformed outwardly when depressed from an inner side thereof. The stencil clamping base
102
is provided with clamping means
107
. Perforated stencil sheet
106
is fixed to the stencil clamping base
102
at a front side thereof by the clamping means
107
and is made to wrap on an outer circumferential surface of the screen member
105
.
At an inner portion of the printing drum
100
, a squeegee roller
110
is vertically movably provided. The squeegee roller
110
is lifted and lowered at a predetermined timing in synchronism with rotation of the printing drum
100
and presses the screen member
105
outwardly. Ink supplying means, not illustrated, supplies a constant amount of ink onto a peripheral face of the squeegee roller
110
.
On a lower side of the printing drum
100
, a press drum
200
which is a back press roller is arranged. A diameter of the press drum
200
is substantially the same as that of the printing drum
100
. A rotational axis line
201
of the press drum
200
and the central axis line
104
of the printing drum
100
are in parallel with each other. In a nonprinting state, a very small clearance is provided between the printing drum
100
and the press drum
200
. The press drum
200
is driven to rotate in a direction reverse to that of the printing drum
100
in synchronism with rotation of the printing drum
100
.
A recess portion
202
is formed at an outer circumferential surface of the press drum
200
. When the printing drum
100
and the press drum
200
are rotated in synchronism with each other, the recess portion
202
corresponds to the clamping means
107
of the printing drum
100
. Therefore, even when a clearance between the printing drum
100
and the press drum
200
is very small, the clamping means
107
does not collide with the press drum
200
.
A clamp
203
is provided at proximity of the recess portion
202
of the press drum
200
. The clamp
203
holds a front end of print sheet supplied between the printing drum
100
and the press drum
200
. The print sheet is held by the clamp
203
, thereafter, sandwiched between the press drum
200
and printing drum
100
in accordance with rotation of the press drum
200
and is fed forwardly.
At proximity of the press drum
200
, a pinch roller
300
is rotatably provided. The pinch roller
300
is arranged side by side on a sheet discharge side of the press drum
200
. The pinch roller
300
presses the print sheet immediately after having been printed to the press drum
200
and peels off the print sheet from the printing drum
100
. Two pieces of the pinch rollers
300
are brought into contact with two edge portions in the width direction of the print sheet. A clearance between the two pieces of pinch rollers
300
in the axial direction can be adjusted in accordance with a width of the print sheet.
The print sheet is supplied between the printing drum
100
and the press drum
200
. The squeegee roller
110
is lowered and presses the screen member
105
outwardly at the predetermined timing. The screen member
105
and stencil sheet
106
which are deformed outwardly, sandwich the print sheet between the press drum
200
and the screen member
105
and stencil sheet
106
. The print sheet is carried while being sandwiched between the deformed printing drum
100
and the press drum
200
. While the print sheet is being carried, ink supplied to an inner circumferential face of the screen member
105
, passes through the screen member
105
and stencil sheet
106
, is transcribed onto the print sheet and forms an image.
When the stencil printing machine is brought into a standby state, the printing drum
100
and the press drum
200
are brought into a positional relationship shown by FIG.
15
. That is, the clamping means
107
of the printing drum
100
and the recess portion
202
of the press drum
200
coincide with each other. Therefore, the pinch roller
300
is brought into contact with the outer circumferential surface of the press drum
200
. Under the state, the two pieces of pinch rollers
300
can not be moved in the axial direction in accordance with the width of the print sheet. In order to move the pinch rollers
300
in the axial direction, it is necessary to rotate the press drum
200
to a pinch roller moving position shown in FIG.
16
and coincide the recess portion
202
of the press drum
200
with the pinch rollers
300
to thereby enable to move the pinch rollers
300
without resistance.
As has been explained above, according to the conventional stencil printing machine, a time period for moving the press drum
200
is needed for adjusting positions of the pinch rollers
300
. The time period for moving the press drum
200
is added to first print time and start up time for printing. The first print time indicates a time period from when a print button is depressed until a sheet of printed matter is discharged. It is generally recognized that the shorter the time period the higher the function of the printing machine and shortening of the first print time has been desired.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a rotary type stencil printing machine having short first print time since positions of pinch rollers can be adjusted without rotating a press drum.
According to a first aspect of the present invention, there is provided a rotary type stencil printing machine comprising a printing drum (
2
) on which a perforated stencil sheet is made to wrap and which is rotated, a press drum (
10
) arranged at a vicinity of the printing drum and rotated in a direction reverse to a direction of the printing drum, pinch rollers (
15
) rotatably provided at a vicinity of the press drum for pressing a print sheet to the press drum such that the print sheet, which has been sandwiched between the printing drum and the press drum and printed, is held and carried by the press drum, pinch roller position adjusting means for adjusting positions of the pinch rollers in an axis line direction such that the pinch rollers can be brought into contact with predetermined positions of the print sheet, pinch roller releasing means for moving the pinch rollers between pinch positions at which the pinch rollers are brought into contact with the press drum and release positions at which the pinch rollers are separated from the press dr
Funk Stephen R.
Riso Kagaku Corporation
LandOfFree
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