Printing – Stenciling – Stencils
Reexamination Certificate
2000-09-11
2001-09-04
Asher, Kimberly L. (Department: 2854)
Printing
Stenciling
Stencils
C101S116000, C101S118000, C101S128100, C101S128400
Reexamination Certificate
active
06283021
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a printing device which carries out a stencil-making process in which an image is written on a stencil sheet by using a printing head and a stencil-attaching process in which the stencil sheet is wrapped around a drum, prior to a printing operation, and more specifically, relates to a stencil making and attaching method thereof.
2. Description of the Related Art
An explanation will be given of conventional stencil making and attaching methods in a printing device of this type.
As illustrated in
FIG. 1
, an elongated stencil sheet
100
, is housed in an sheet housing section (not shown), and on the downstream side of the sheet conveying path, a thermal print head
101
, which is a printing head for forming pores corresponding to an image in the stencil sheet
100
, and a platen roller
102
, which is pressed onto the thermal print head
101
with the stencil sheet
100
interposed in between, are installed.
On the downstream side of the platen roller
102
in the stencil sheet conveying path, a pair of first convey rollers
103
are placed in a virtually press-contact state, and the platen roller
102
and one of the first convey rollers
103
are designed so as to be rotated in synchronism with the platen roller
102
by the rotating force of a stencil motor, not shown.
On the downstream side of the pair of first convey rollers
103
in the stencil sheet conveying path, a pair of second convey rollers
104
are placed in a virtually press-contact state, and on the further downstream side of the pair of second convey rollers
104
in the stencil sheet conveying path, a pair of third convey rollers
105
are placed in a virtually press-contact state. The respective ones of the second convey rollers
104
and the third convey rollers
105
are designed to be rotated by the rotating force of a convey motor, not shown, in synchronism with each other.
Moreover, a sheet temporary stacker section
106
is installed at a lower position between the pair of first convey rollers
103
and the pair of second convey rollers
104
. A stencil sheet cutter section
107
is installed between the pair of second convey rollers
104
and the pair of third convey rollers
105
, and a stencil sheet set position detection sensor
108
is placed on the downstream side of the pair of third convey rollers
105
in the stencil sheet conveying path.
The stencil sheet set position detection sensor
108
is constituted by a reflection-type photo-sensor, and when the leading end of the stencil sheet
100
has been conveyed to a position below this, it detects the existence thereof.
Furthermore, on the downstream side of the stencil sheet set position detection sensor
108
, a drum
109
is installed so as to be freely rotated, and this drum
109
is arranged to be rotated by the rotating force of a drum motor, not shown. A stencil sheet clamp section
110
is installed on the periphery of the drum
109
, and the leading end of the stencil sheet
100
is clamped by this stencil sheet clamping section
110
.
Next, in the above-mentioned arrangement, referring to
FIGS. 1 through 5
, an explanation will be given of stencil making and attaching methods of the stencil sheet
100
. Here, suppose that the leading end of the stencil sheet
100
is only inserted between the thermal print head
101
and the platen roller
102
and that the drum
109
is positioned at a drum reference position at which the drum
109
is allowed to carry out the stencil sheet clamping process.
In this state, the stencil motor and the convey motor are both driven so that the platen roller
102
, the first convey rollers
103
, the second convey rollers
104
and the third convey rollers
105
are rotated so that the stencil sheet
100
is conveyed to the drum side. Here, when the leading edge of the stencil sheet
100
has reached the position below the stencil sheet set position detection sensor
108
, the stencil sheet set position detection sensor
108
detects this, with the result that the conveyance of the stencil sheet
100
is stopped. In this case, the leading edge of the stencil sheet
100
is positioned at a stencil sheet setting position as shown in FIG.
1
.
Next, as shown in
FIG. 2
, the stencil motor is driven to rotate the platen roller
102
and the first convey roller
103
so that, while the stencil sheet
100
is being conveyed, pores corresponding to a desired image are formed in the stencil sheet
100
through a heat-sensitive process by the thermal print head
101
, thereby carrying out a stencil making process. The stencil sheet
100
which has been subjected to the stencil making process is temporarily housed in a temporary stacker section
106
.
Next, as shown in
FIG. 3
, the convey motor is driven to rotate the second convey roller
104
and the third convey roller
105
so that the stencil sheet
100
is conveyed to the drum side by a predetermined amount. Then, this convey process by the predetermined amount allows the leading edge of the stencil sheet
100
to reach the position of the stencil sheet clamp section
110
of the drum
109
, with the result that the stencil sheet clamp section
110
clamps the leading edge of the stencil sheet
100
.
Successively, as shown in
FIG. 4
, the drum motor is driven to rotate the drum
109
in the arrow direction so that the stencil sheet
100
is gradually wrapped around the periphery of the drum
109
. Further, as shown in
FIG. 5
, when this has been wrapped to a stencil sheet cut position, the rotation of the drum
109
is temporarily stopped so that the stencil sheet
100
is cut by the stencil sheet cutter section
107
. After the cutting process, the drum motor is again driven so that the drum
109
is rotated so that the stencil sheet
100
is completely wrapped around the periphery of the drum
109
, thereby completing the stencil attaching process. After completion of the stencil attaching process, a sheet of printing paper (not shown) is supplied to the drum
109
in synchronism with the rotation of the drum
109
, and the sheet of printing paper is conveyed while being pressed onto the stencil sheet
100
wrapped around the drum
109
; thus, during this conveying process, ink is transferred onto the sheet of printing paper through the pores of the stencil sheet
100
, thereby carrying out a printing process.
In the above-mentioned stencil making and attaching method, as shown in
FIG. 6
, a position corresponding to a distance L
1
from the leading edge of the stencil sheet
100
to the thermal print head
101
is defined as the image-formation start position, and as shown in FIG.
7
(A), the leading edge of the stencil sheet
100
that has been subjected to the image formation is clamped at a clamp reference position of the drum
109
so that the image-formation start position is set at a fixed position. Then, a sheet of printing paper is conveyed in synchronism with the rotation of the drum
109
so that an image is always formed at a predetermined position on the sheet of printing paper.
However, the distance L
1
from the leading edge of the stencil sheet
100
to the image-formation start position fails to provide an accurate length in the event of curing, etc. in the stencil sheet
100
as indicated by a hypothetical line in
FIG. 7
or in the event of variations in the detection of the stencil sheet set position detection sensor
108
. Moreover, with respect to the clamp position of the drum
109
, clamping is not made at an accurate position when a slip, etc. of the stencil sheet
100
occurs with respect to the second convey roller
104
and the third convey roller
105
, as shown in FIGS.
7
(B) and
7
(C). In this manner, when the image-formation position of the stencil sheet
100
and the clamp position with respect to the drum
109
are not accurate, the image-formation position of the stencil sheet
100
with respect to the drum
109
is offset from the regular position, with the result that an offset occurs in the print position on a sheet of printing
Kimura Kaoru
Miyata Masakazu
Watanabe Hitoshi
Asher Kimberly L.
Berkowitz Marvin C.
Crenshaw Marvin P.
Nath Gary M.
Nath & Associates PLLC
LandOfFree
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