Printing – Stenciling – Rotary machines
Reexamination Certificate
2000-03-21
2001-11-20
Grohusky, Leslie J. (Department: 2854)
Printing
Stenciling
Rotary machines
C101S128400, C400S120180
Reexamination Certificate
active
06318254
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a stencil printing machine in which a stencil sheet is perforated by a thermal head and a platen roller and then wound around a printing drum for stencil printing.
2. Description of the Related Art
FIG. 2
is a sectional view showing a part of a stencil printing machine where a stencil sheet is used.
The stencil sheet
100
in a roll is perforated by a thermal head
101
and a platen roller
102
of a perforating section while being pinched and conveyed therebetween. The stencil sheet is conveyed by conveying rollers
103
into a storing section
104
and stored therein. While a used stencil sheet wound around the printing drum
105
is discharged, the stencil sheet in a length to be used for one printing-operation is previously perforated and stored in the storing section
104
. The stencil sheet
100
previously perforated is fed out by rollers
106
in a predetermined timing and conveyed to the printing drum
105
. A leading end of the stencil sheet
100
is held on the printing drum
105
by a clamp plate
107
, and the sheet is wound around the printing drum by rotating the printing drum. Then, the stencil sheet
100
is cut by a cutter
108
in the length for one printing-operation. Nest,a printing sheet is fed between the printing drum
105
and a pressing roller
109
in synchronization with rotation of the printing drum
105
and upward movement of the pressing roller
109
. The printing sheet is printed while being pinched and conveyed between the printing drum
105
and the pressing roller
109
.
The stencil sheet is composed of a thermoplastic synthetic resin film such as a plastic film, and a porous substrate laminated with the film. As the porous substrate, there can be mentioned porous thin paper such as Tengujo-type Japanese paper, porous sheet made from synthetic fibers, woven fabric, and non-woven fabric. The stencil sheet is normally conveyed by the perforating section in such a manner that the thermal head
101
contacts the thermoplastic synthetic resin film and the platen roller
102
contacts the porous substrate.
The stencil sheet is charged with static electricity while being pinched and perforated by the thermal head and the platen roller. That is, high nip pressure is exerted on the stencil sheet by the thermal head and the platen roller, so that the stencil sheet is conveyed in forceful contact with the thermal head and the platen roller during perforating. Therefore, the static electricity charge is inevitable.
Thus, a problem arises as shown in FIG.
2
. Namely, the stencil sheet
100
sticks to a circumferential surface of the platen roller
102
. Additionally, the stencil sheet
100
is distorted in a twisting way in the storing section
104
by the static electricity. If the stencil sheet
100
passes through the rollers
106
when it is conveyed to the printing drum
105
, the stencil sheet
100
is folded. Therefore, the stencil sheet is wrinkled when being wound around the printing drum after being stretched. Further, a conveying path of the stencil sheet
100
is made of metal plates, and this causes another problem that the stencil sheet
100
sticks to the metal plates by the static electricity, so that the conveyance of the stencil sheet is intercepted.
The object of the present invention is to solve the problems of the static electricity charged on the stencil sheet in the stencil printing machine in which the stencil sheet is perforated by the thermal head and the platen roller.
SUMMARY OF THE INVENTION
A stencil printing machine according to a first aspect of the invention comprises a thermal head for perforating a stencil sheet; a platen roller situated adjacent to the thermal head, the platen roller conveying the stencil sheet in a predetermined direction while holding the stencil sheet in contact with the thermal head; a printing drum situated near the thermal head and the platen roller, the printing drum being adapted to receive said stencil sheet perforated by the thermal head and the platen roller; and a discharging member situated near the platen roller on a downstream side of the predetermined direction relative to the thermal head and the platen roller, the discharging member discharging static electricity charged on the stencil sheet.
In a stencil printing machine according to a second aspect of the present invention, the stencil printing machine is formed according to the first aspect, wherein the discharging member is situated to contact one surface of the stencil sheet, the one surface contacting the platen roller.
In a stencil printing machine according to a third aspect of the present invention, the stencil printing machine is formed according to the first aspect, wherein the discharging member is situated to contact one surface of the stencil sheet, the one surface contacting the thermal head.
In a stencil printing machine according to a fourth aspect of the present invention, the stencil printing machine is formed according to the first aspect, wherein the stencil printing machine further comprises a storing section situated between the printing drum and both of the thermal head and the platen roller, the storing section temporarily storing the stencil sheet perforated by the thermal head and the platen roller.
In a stencil printing machine according to a fifth aspect of the present invention, the stencil printing machine is formed according to the fourth aspect, wherein the discharging member is situated to an entrance of the storing section.
REFERENCES:
patent: 5513919 (1996-05-01), Hevenor
patent: 5970869 (1999-10-01), Hara et al.
patent: 6050184 (2000-04-01), Kidoura et al.
Saitoh Takeshi
Sakai Toshimitsu
Grohusky Leslie J.
Kanesaka & Takeuchi
Riso Kagaku Corporation
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