Printing – Stenciling – Rotary machines
Reexamination Certificate
2002-01-31
2004-06-08
Evanisko, Leslie J. (Department: 2854)
Printing
Stenciling
Rotary machines
C101S116000, C271S197000, C271S196000
Reexamination Certificate
active
06745685
ABSTRACT:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
The present invention relates to a stencil printing machine having a sheet transfer apparatus for discharging sheet formed with an image.
FIG. 21
shows a general stencil printing machine.
On one side of the stencil printing machine, there is provided a sheet supply base
100
loaded with print sheet P. The print sheet P is supplied to inside of the stencil printing machine by separating only a topmost sheet thereof by a separating roller
101
.
The supplied print sheet P is transferred to a side of a printing drum
103
provided at inside of the stencil printing machine at predetermined timings by register rollers
102
.
The printing drum
103
is constituted by forming an ink-permeable peripheral wall
104
in a cylindrical shape and is rotated in the counterclockwise direction of
FIG. 21
around an axis line of the printing drum
103
per se. A perforated stencil sheet is wound around an outer peripheral face of the printing drum
103
. At an inner portion of the printing drum
103
, there is provided ink supply means
105
for supplying ink to an inner peripheral face of the printing drum
103
. At outside of the printing drum
103
, there is provided a press roller
106
moved attachably to and detachably from the outer peripheral face of the printing drum
103
at a position opposed to the ink supplying means
105
.
Further, the print sheet P transferred by the register rollers
102
, is brought into press contact with the stencil sheet disposed on the outer peripheral face of the printing drum
103
by the press roller
106
and one face thereof is transcribed with ink extruded from the inner peripheral face of the printing drum
103
via perforated portions of the stencil sheet.
The printed print sheet P is transferred by rotation of the printing drum
103
and is discharged to a sheet discharge base
109
provided on other side (side opposed to the sheet supply base
100
) of the stencil printing machine by a sheet transfer apparatus according to a vacuum conveyor (suction belt) system having a vacuum fan
107
and a sheet transfer belt
108
. A series of printing operation is carried out in this way.
In the above-described series of printing operation, the print sheet P brought into press contact to the side of the printing drum
103
by the press roller
106
, is pasted to the side of the stencil sheet disposed on the outer peripheral face of the printing drum
103
by adhering force of ink.
Hence, conventionally, there is provided a separating claw
110
having a sharpened front end in front of the sheet transfer apparatus disposed on a sheet transferring side of the printing drum
103
. The separating claw
110
catches the print sheet P pasted to the side of the printing drum
103
to thereby separate the print sheet P from the side of the printing drum
103
.
Further, conventionally, in addition to (or in place of) the separating claw
110
, there is provided an air blow fan
111
in front of the sheet transfer apparatus disposed on the sheet transferring side of the printing drum
103
. By air blowing force of the air blow fan
111
, the print sheet P is separated from the side of the printing drum
103
.
However, according to the above-described conventional stencil printing machine, in the case of the separating claw
110
, when the print sheet P is separated from the side of the printing drum
103
, the separating claw
110
is brought into direct contact with the printed image face of the print sheet P and therefore, there poses a problem that an image portion is scraped and print quality is deteriorated.
Further, in the case of the air blow fan
111
, there is produced a negative pressure region on the downstream side of an air flow at a vicinity of a blow out port thereof. Further, when the print sheet P is separated from the side of the printing drum
103
, the print sheet P to be directed to the side of the sheet transfer apparatus, may be attracted to the side of the air blow fan
111
by suction operation of the negative pressure region and brought into contact with the blow out port of the air blow fan
111
. Thereby, the image portion of the print sheet P is scraped similar to the case of the separating claw
110
and there poses a problem that the print quality is deteriorated.
Meanwhile, when a printing rate of the print image is large, that is, when a solid portion is large, the adhering force of ink is increased and the print sheet P becomes difficult to separate from the side of the printing drum
103
. That is, time of separating the print sheet P from the side of the printing drum
103
is retarded and a time period of holding the print sheet P on the side of the printing drum
103
is prolonged.
Thereby, for example, although a transfer front end side of the print sheet P is going to be separated and transferred by the sheet transfer apparatus, a transfer rear end side thereof remains at the side of the printing drum
103
air without being separated from the side of the printing drum
103
. Therefore, there poses a problem that the transfer rear end side of the print sheet P is flown up and in the worst case, sheet discharge jam is caused and the printing operation is interrupted.
Further, when the printing rate differs on the left and right sides of a direction of transferring the print sheet P, time of separating the print sheet P from the side of the printing drum
103
differs on the left side and on the right side. Thereby, there is a concern that transmission of the print sheet P to discharge is meandered or the sheet discharge jam is caused by the meandering.
Further, ink forms a printed image mainly by a mode of permeating to the print sheet P. However, when the time period of holding the print sheet P on the side of the printing drum
103
, is long as mentioned above, ink of an amount more than necessary is transcribed to the print sheet P by the capillary phenomenon of ink.
When an amount of transcribing ink is as much as more than necessary in this way, the printed image portion is blotted to thereby deteriorate print quality or gradation is produced at a solid portion. Further, there causes a drawback that excess ink remaining on the surface of the print sheet P without being permeated, is brought into contact with a rear face of the print sheet P to be discharged successively and setoff is caused.
Although in each stencil sheet, the printing rate of the printed image respectively differs variously, when the printing rate differs considerably, a timing of separating the print sheet P from the side of the printing drum
103
differs.
That is, when the transfer front end side of the print sheet P is separated to the side of the sheet transfer apparatus, a track of exfoliating the transfer front end is changed and a position of the front end of the sheet is changed. Further, when the printing rate differs on the left side and on the right side of the transfer direction of the print sheet P, the print sheet P meanders as mentioned above and therefore, when the transfer front end side of the print sheet P is separated to the side of the sheet transfer apparatus, the position of the front end of the sheet meanders.
When the position of the front end of the print sheet P is changed in this way, particularly in the case of a stencil printing machine for carrying out multiple block printing or double-faced printing by providing other printing drum (not illustrated) at a post stage of the printing drum
103
, there poses a problem that a printed image printed by the post stage of the printing drum shifts relative to the image of the print sheet P printed by the printing drum
103
at the initial stage.
Hence, in order to resolve the above-described problem, it is an object of the invention to provide a stencil printing machine capable of separating print sheet from a side of a printing drum and capable of separating print sheet from the side of the printing drum to align a position of a front end of sheet, regardless of a printing rate of printing and without being brought into conta
Kinoshita Hideyuki
Naitou Taku
Evanisko Leslie J.
Kanesaka & Takeuchi
Riso Kagaku Corporation
LandOfFree
Stencil printing device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Stencil printing device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Stencil printing device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3332719