Information
-
Patent Grant
-
6510789
-
Patent Number
6,510,789
-
Date Filed
Friday, September 28, 200123 years ago
-
Date Issued
Tuesday, January 28, 200321 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Nath; Gary M.
- Novick; Harold L.
- Berkowitz; Marvin C.
-
CPC
-
US Classifications
Field of Search
US
- 101 114
- 101 115
- 101 116
- 101 117
- 101 118
- 101 119
- 101 120
- 101 126
- 101 129
- 101 483
- 101 484
- 101 184
- 101 185
-
International Classifications
-
Abstract
A stencil printing machine and a method carrying out a printing operation are disclosed wherein a print sheet is transferred through between an upstream printing drum and a press roller in a pressured state to transfer ink onto an upper surface of the print sheet and is then transferred through between a downstream printing drum and a press roller in a pressured state to transfer ink onto the other surface of the print sheet to perform a both sides printing operation. A printing-drum drive escape mechanism is located to shift the downstream printing drum to a drive escape position to interrupt rotation of the printing drum while retaining the press roller in a separated position away from the shifted printing drum in such a manner that the printing operation under such a condition in a one side printing mode is executed.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a stencil printing machine and a method, and more particularly, to a stencil printing machine having two sets of printing sections in each of which a print medium is transferred through a path between a printing drum which carries thereon a stencil sheet and a pressure rotary member which is provided to the associated printing drum for thereby selectively carrying out a printing operation in a both sides printing mode and in a one side printing mode, and to a method of selectively carrying out a printing operation in a both sides printing mode and in a one side printing mode.
A stencil printing machine that enables a both sides printing operation with the use of two sets of printing sections is shown in FIG.
7
.
FIG. 7
shows an overall structure of the stencil printing machine for the both sides printing operation.
In
FIG. 7
, the stencil printing machine
100
is constructed of upstream and downstream stencil making sections
104
,
105
with respective thermal printing heads
102
,
103
for thermally perforating respective stencil sheets
101
,
101
on the basis of respective image data, an upstream printing section
109
wherein the stencil sheet
101
made in the upstream stencil making section
104
is mounted onto an upstream printing drum
106
and a print sheet
107
, which is fed thereto, is transferred through a path between the upstream printing drum
106
and a press roller
108
in a pressured contact relationship to transfer ink onto an upper surface (one surface) of the print sheet
107
during such a transfer step, a paper feed section
110
which feeds the print sheet
107
to the upstream printing section
109
, an upstream belt-conveyer transfer unit
111
located at a sheet discharge side of the upstream printing section and transferring the print sheet
107
to a downstream side with the action of a belt
121
, a downstream printing section wherein the stencil sheet
101
, which is made in the downstream stencil making section
105
, is mounted onto a downstream printing drum
112
and the print sheet, which is fed from the upstream belt conveyer transfer unit
111
, is transferred through a path between the printing drum
112
and a press roller
114
in a pressured contact relationship to transfer ink onto a lower surface (the other surface) of the print sheet
107
during such a transfer step, and a downstream belt-conveyer transfer unit
117
with a belt
122
located at a sheet discharge side of the downstream printing section
115
for transferring the print sheet
107
to a sheet discharge tray
116
located in a downstream side.
Further, the upstream and downstream printing sections
109
,
115
include squeegee rollers
123
,
123
located inside the printing drums
106
,
112
, respectively, and held in contact with inner surfaces of outer peripheral walls
106
a
,
112
a
of the respective printing drums
106
,
112
, doctor rollers
124
,
124
located in close proximity to the squeegee rollers
123
,
123
, respectively, to form respective given gaps relative thereto, and ink supply units
125
,
125
each for supplying ink to an each area between the rollers
123
,
124
, with the squeegee rollers
123
,
123
being arranged to rotate on inner peripheral surfaces of the outer peripheral walls
106
a
,
112
a
in association with rotations of the respective printing drums
106
,
112
. In addition, as the squeegee rollers
123
,
123
rotate with, the rotations of the printing drums
106
,
112
, the outer peripheral surfaces of the squeegee rollers
123
,
123
are adhered with ink in a given film thickness, with the adhered ink being.transferred to the outer peripheral walls
106
a
,
112
a
to allow ink to be supplied to an inner side of the print sheet
101
at all times.
Now, the both .sides printing operation is described below. Rotations of the printing drums
106
,
112
allow the print sheet
107
to be fed from the paper feed section
110
to the upstream printing drum
106
in synchronism with the rotation thereof. The print sheet
107
, thus fed to the printing drum
106
, is brought into pressured contact with the stencil sheet
101
of the printing drum
106
with the press roller
108
to allow ink image to be transferred onto the upper surface of the print sheet
107
, with the print sheet
107
, whose upper surface is printed, being peeled off from the outer peripheral wall of the printing drum
106
and being introduced to the upstream conveyer-belt transfer unit
111
. The upstream belt-conveyer transfer unit
111
causes the belt
121
to move for transferring the print sheet
107
with its lower surface remaining contact with the belt, thereby feeding the print sheet
107
from the most downstream side of the belt
121
to the downstream printing drum
112
. The print sheet
107
, thus fed to the downstream printing drum
106
, is then brought into pressured contact with the stencil sheet
101
of the printing drum
112
with the press roller
114
to transfer ink image onto the lower surface of the print sheet
107
, with the print sheet
107
, whose lower surface is printed, being peeled off from the outer peripheral wall of the printing drum
112
to be introduced to the downstream belt-conveyer transfer unit
117
. The downstream belt-conveyer transfer unit
117
causes the belt
122
to move for transferring the print sheet
107
from the most downstream side of the belt
122
to the sheet discharge tray
116
. The print sheet
107
thus discharged to the sheet discharge tray
116
is placed therein in the stacked state.
Also, such a stencil printing machine is disclosed in Japanese Patent Application Laid-Open Publication No. 8-90893.
In the aforementioned stencil printing machine for the both sides printing operation, it is desired to achieve a one side printing operation and, so, various attempts have been conducted in the related art. For example, one technology to achieve this end concerns the two printing drums
106
,
112
, one of which is mounted with a stencil sheet
101
which is perforated on the basis of image data, and the other one of which is mounted with a non-perforated stencil sheet
101
. With such arrangement, when executing the printing operation in the same manner as the both sides printing operation, the print sheet is transferred with ink at the printing section mounted with the perforated stencil sheet
101
whereas the print sheet is not transferred with ink at another printing section mounted with the non-perforated stencil sheet
101
, thereby achieving the one side printing operation.
An alternative approach to achieve the one side printing operation is to locate a transfer unit at the discharge side of the upstream printing section
109
to transfer the print sheet
107
in another route to the sheet discharge tray without directing the print sheet
107
to the downstream printing section
115
. With such a structure, during the one side printing mode, the print sheet
107
, which is printed in the upstream printing section
109
, is discharged in another route, thereby achieving the one side printing operation.
SUMMARY OF THE INVENTION
However, in the former one side printing technology, the presence of the need for mounting the non-perforated stencil sheet onto one of the printing drums induces the waste of the stencil sheets. In the latter one side printing technology, the presence of the need for additionally locating the transfer unit as an extra printing drum mechanism in another route specific for the one side printing operation is a major cause of an inherent large size in structure and an increase in manufacturing cost.
Since, further, the two printing drums
106
,
112
must be rotated in synchronism with one another while retaining a given rotational angular phase difference, it is a usual practice to employ a single drive source for rotating both of these printing drums. Accordingly, if the printing drum
106
(or
112
), which is not in charge of the one side printing operation, is rotated, this rotation of the printing drum causes the squeegee roller
123
remaining inside the printing drum to rotate, with a resultant undesired continuous operation of the squeegee roller
123
to supply ink to the outer peripheral wall
106
a
(or
112
a
) of the printing drum
106
(or
112
). Since, however, this ink is not transferred to the print sheet
107
and is merely subjected to an undesired kneaded result, another problem is encountered in that an excessive amount of kneading frequencies of ink results in deterioration of quality.
The present invention has been made in view of the above studies and has an object to provide a stencil printing machine and a method for performing a printing operation which enable a one side printing operation without causing the waste of stencil sheets, without providing a transfer mechanism in another route for the one side printing operation and also without causing deterioration in the quality of ink.
According to one aspect of the present invention, there is provided a stencil printing machine selectively carrying out a printing operation in a both sides printing mode and in a one side printing mode, which comprises: an upstream printing section including a first printing drum formed with an ink permeable outer peripheral wall adapted to be mounted with a stencil sheet, a first ink supply unit supplying ink to an inner periphery of the first printing drum, and a first press rotary member operative to be held in a pressured position in contact with the outer peripheral wall of the first printing drum to allow ink to be transferred onto one surface of a print medium; a downstream printing section including a second printing drum formed with an ink permeable outer peripheral wall adapted to be mounted with a stencil sheet, a second ink supply unit supplying ink to an inner periphery of the second printing drum, and a second press rotary member operative to be held in a pressured position in contact with the outer peripheral wall of the second printing drum to allow ink to be transferred onto the other surface of the print medium; a paper feed section feeding the print medium to the upstream printing section; and a printing-drum drive escape mechanism operative to shift either selected one of the first and second printing drums into a drive escape position to interrupt rotation of the selected printing drum while retaining either selected one, associated with the selected printing drum, of the first and second press rotary members in a separated position to pass the print medium into a sheet discharge section along the selected printing drum without contact with the selected press rotary member, in the one side printing mode.
Besides according to the present invention, a method, which selectively carries out a printing operation in a both sides printing mode and in a one side printing mode, provides an upstream printing section including a first printing drum and a first press rotary member operative to shift between a pressured position and a separated position relative to the first printing drum; provides a downstream printing section including a second printing drum and a second press rotary member operative to shift between a pressured position and a separated position relative to the second printing drum; provides a printing-drum drive escape mechanism operative to enable a shift of either selected one of the first and second printing drums into a drive escape position; feeds a print medium to the upstream printing section; and feeds the print medium, which is discharged from the first printing drum of the upstream printing section, to the downstream printing section. Here, when the one side printing mode is selected, the printing-drum drive escape mechanism is operative to shift either selected one of the first and second printing drums to a drive escape position to render the selected printing drum inoperative and to render the selected press rotary member to remain in a separated position away from the selected printing drum to pass the print medium into a sheet discharge section along the selected printing drum without contact with the selected press rotary member, in the one side printing mode.
Other and further features, advantages, and benefits of the present invention will become more apparent from the following description taken in conjunction with the following drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a schematic structural view of a stencil printing machine according to an embodiment of the present invention;
FIGS. 2A and 2B
show a downstream printing-drum drive escape mechanism according to the embodiment of the present invention, wherein
FIG. 2A
is a plan view of the downstream printing-drum drive escape mechanism where the printing drum remains in an operative, drive position and
FIG. 2B
is a plan view of the downstream printing-drum drive escape mechanism where the printing drum remains in an inoperative, drive escape position;
FIG. 3
is a block diagram for illustrating a control circuitry to perform a drive escape operation for the relevant printing drum of the stencil printing machine according to the embodiment of the present invention;
FIG. 4
is a general flow diagram for illustrating the basic sequence of the drive escape operation to be carried out when a one side printing mode is selected to perform a method according to the embodiment of the present invention;
FIG. 5
is a general flow diagram for illustrating the basic sequence of operation for restoring the relevant printing drum from the drive escape condition to be carried out when a both sides printing mode is selected to perform the method according to the embodiment of the present invention;
FIG. 6
is a summary structural view for illustrating operative conditions of the upstream printing section and the downstream printing section during the one side printing mode according to the embodiment of the present invention; and
FIG. 7
is an overall structural view of a stencil printing machine studied by the present inventor.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
To describe the present invention more in detail, an embodiment of a digital type stencil printing machine and a method for the stencil printing machine according to the present invention will be described below in detail with reference to the drawings.
(Structural Overview of Stencil Printing Machine)
FIGS. 1
to
6
show a stencil printing machine of a typical embodiment of the present invention to carry out a method of the present invention, wherein
FIG. 1
shows a schematic overall structural view of the stencil printing machine,
FIG. 2A
is a plan view of a downstream printing-drum drive escape mechanism by which the relevant printing drum remains in an operative, drive-connection state,
FIG. 2B
is a plan view of the downstream printing-drum drive escape mechanism by which the relevant printing drum remains in an inoperative, drive escape position,
FIG. 3
is a block diagram of a control circuitry to perform a drive escaping operation for the relevant printing drum,
FIG. 4
is a flow diagram of the drive escape operation to be performed when a one side printing mode is selected,
FIG. 5
is a flow diagram of the drive escaping operation to be performed when a both sides printing operation mode is selected, and
FIG. 6
is a summary structural view for illustrating operative conditions of an upstream printing section and a downstream printing section in the one side printing mode.
Referring to
FIG. 1
, the digital type stencil printing machine
1
is mainly constructed of an original read out section (not shown), an upstream stencil making section
2
, a downstream stencil making section
3
, an upstream printing section
4
, a downstream printing section
5
, a paper feed section
6
, an upstream belt transfer unit
7
, a downstream belt transfer unit
8
, a sheet discharge section
9
, an upstream stencil disposal section
10
and a downstream stencil disposal section
11
.
Original Readout Section
The original read out section (not shown) includes, for example, an automatic paper feed and read out unit for obtaining image data by automatically feeding an original, and an original positioning and read out unit for obtaining image data from the original which is positioned in place. The automatic paper feed and read out unit is constructed of an inclined original resting plate to allow the original to be rested, an original feed roller pair for transferring the original resting on the inclined original resting plate, and a line image sensor for obtaining image data by converting contents of the original, which is transferred, to a train of electric signals. The line image sensor is commonly used as that of the original positioning and read out unit.
The original positioning and read out unit includes a horizontal original positioning glass table for allowing the original to be positioned, a pressure plate located on the horizontal original positioning glass table for free opening and closing capabilities, a guide belt located in an area below the horizontal original positioning glass plate to be moveable with a drive force of a pulse motor, and the line image sensor which is guided with the guide belt to move in the area below the original positioning glass plate.
Further, the line image sensor of the automatic paper feed and read out unit has the line image sensor reads out the original, which is transferred with the original feed roller pair, with the line image sensor. In the original positioning and read out unit, the line image sensor is guided and moved with the guide belt to scan a lower surface of the original to read out the contents of the original.
Upstream Stencil Making Section
The upstream stencil making section
2
includes a stencil sheet receiving tray
21
which receives an elongated stencil sheet
20
in the form of a roll, a thermal printing head
22
composed of a writing head which is located at a position downstream of the stencil sheet receiving tray
21
in a transfer direction of the stencil sheet
20
relative to the stencil sheet receiving tray
21
, a platen roller
23
located in opposed relation to the thermal printing head
22
and driven by a pulse motor (not shown), a stencil feed roller pair
24
located downstream of the thermal printing head
22
and the platen roller
23
in the transfer direction of the stencil sheet
20
and rotated with the drive force of the pulse motor (not shown), a stencil feed roller pair
25
located further downstream of the stencil feed roller pair
24
in the transfer direction of the stencil sheet, and a stencil cutter
26
located downstream of the stencil feed roller pair
25
. The thermal printing head
22
includes a plurality of dot-shaped thermal elements located, in a plane perpendicular to the transfer direction of the stencil sheet
20
, to occupy a space in a range equal to a paper size of A3 to meet the maximum size A3 of a print sheet which is intended in the present embodiment.
In addition, rotation of the platen roller
23
and the stencil feed roller pair
24
allows the stencil sheet
20
to be transferred. During such transfer of the stencil sheet
20
, the dot-shaped thermal elements of the thermal printing head
22
are selectively activated to produce heat on the basis of image data, which corresponds to an upper surface (one surface) of the original, read out with the line image sensor to permit thermal perforation in the stencil sheet
20
to form a desired perforated area, with a trailing edge of the stencil sheet
20
, which has the desired perforated area, being cut with the stencil cutter
36
to form a perforated stencil sheet
20
of a given length.
Downstream Stencil Making Section
The downstream stencil making section
3
includes a stencil sheet receiving tray
21
′ which receives an elongated stencil sheet
20
′ in the form of a roll, a thermal printing head
32
composed of a writing head which is located at a position downstream of the stencil sheet receiving tray
21
′ in a transfer direction of the stencil sheet
20
′ relative to the stencil sheet receiving tray
21
′, a platen roller
33
located in opposed relation to the thermal printing head
32
and driven by a pulse motor (not shown), a stencil feed roller pair
34
located downstream of the thermal printing head
32
and the platen roller
33
in the transfer direction of the stencil sheet
20
′ and rotated with the drive force of the pulse motor (not shown), a stencil feed roller pair
35
located further downstream of the stencil feed roller pair
34
in the transfer direction of the stencil sheet, and a stencil cutter
36
located downstream of the stencil feed roller pair
35
. The thermal printing head
32
includes a plurality of dot-shaped thermal elements located, in a plane perpendicular to the transfer direction of the stencil sheet
20
′, to occupy a space in a range equal to a paper size of A3 to meet the maximum size A3 of a print sheet which is intended in the present embodiment.
In addition, rotation of the platen roller
33
and the stencil feed roller pair
34
allows the stencil sheet
20
′ to be transferred. During such transfer of the stencil sheet
20
′, the dot-shaped thermal elements of the thermal printing head
32
are selectively activated to produce heat on the basis of image data, which corresponds to a lower surface (the other surface) of the original, read out with the line image sensor to permit thermal perforation in the stencil sheet
20
′ to form a desired perforated area, with a trailing edge of the stencil sheet
20
′, which has the desired perforated area, being cut with the stencil cutter
36
to form a perforated stencil sheet
20
′ of a given length.
Upstream Printing Section
The upstream printing section
4
is constructed of an upstream printing drum
40
that includes an outer peripheral wall
40
a
composed of an ink permeable member formed in a perforated structure and that rotates in a direction as shown by an arrow A in
FIG. 1
with a drive force of a main motor M (see FIG.
3
), and a stencil clamping segment
41
mounted to the outer periphery
40
a
of the printing drum
40
for clamping a leading edge of the stencil sheet
20
.
Further, the upstream printing section
4
includes a squeegee roller
42
located inside the outer peripheral wall
40
a
and held in contact with an inner peripheral surface of the outer peripheral wall
40
a
, a doctor roller
43
spaced from the squeeze roller
42
with a given gap, an ink supply unit
44
for supplying ink to an area between the rollers
42
,
43
, a press roller
46
which is located in an area outside the printing drum
40
in opposed relation to the squeeze roller
42
via the outer peripheral wall
40
a
thereof and which serves as a rotating press member, and a pressure exerting unit (not shown) which selectively moves the press roller
46
into a pressured engagement position, (a position as indicated by a solid line in
FIG. 1
) to urge the press roller
46
against the outer peripheral wall
40
a
of the printing drum
40
, and a separated position (a position indicated by a phantom line in
FIG. 1
) to separate the press roller
46
from the outer peripheral wall
40
a
of the printing drum
40
. The press roller
46
functions to move between the pressured engagement position and the separated position in association with rotation of the printing drum
40
during the printing operation such that, during transit of the print sheet
45
, which serves as a print medium, transferred in synchronism with rotation of the printing drum
40
, the press roller
46
remains in the pressured engagement position and, during other operating phase (i.e., during non-transit of the print sheet
45
), the press roller
46
remains in the separated position.
With such a structure, clamping the leading edge of the stencil sheet
20
, which is transferred from the upstream stencil making section
2
, with the stencil clamping segment
41
, while permitting rotation of the printing drum
40
under the clamped state of the stencil sheet
20
allows the stencil sheet
20
to be wound around and mounted to the outer periphery
40
a
of the printing drum
40
. When this occurs, the print sheet
45
, which is transferred in synchronism with the rotation of the printing drum
40
, is brought into pressured contact with the stencil sheet
20
of the printing drum
40
with the action of the press roller
46
, allowing ink to be transferred through the perforated area of the stencil sheet
20
onto the upper surface (the one surface) of the print sheet
45
to reproduce a desired image thereon.
Downstream Printing Section
The downstream printing section
5
is constructed of a downstream printing drum
50
that includes an outer peripheral wall
50
a
composed of an ink permeable member formed in a perforated structure and that rotates in a direction as shown by an arrow B in
FIG. 1
with a drive force of a main motor M (see FIG.
3
), and a stencil clamping segment
51
mounted to the outer periphery
50
a
of the printing drum
50
for clamping a leading edge of the stencil sheet
20
′. The downstream printing drum
50
is able to shift to a drive escape position to interrupt a drive connection between the main motor M and the downstream printing drum
50
by means of a printing-drum drive escape mechanism
76
.
Further, the downstream printing section
5
includes a squeegee roller
52
located inside the outer peripheral wall
50
a
and held in contact with an inner peripheral surface of the outer peripheral wall
50
a
, a doctor roller
53
spaced from the squeeze roller
52
with a given gap, an ink supply unit
54
for supplying ink to an area between the rollers
52
,
53
, a press roller
56
which is located in an area outside the printing drum
50
in opposed relation to the squeeze roller
52
via the outer peripheral wall
50
a
thereof and which serves as a rotating press member, a pressure exerting unit (not shown) which selectively moves the press roller
56
into a separated position (a position as indicated by a solid line in
FIG. 1
) to urge the press rolled
56
against the outer peripheral wall
50
a
of the printing drum
50
and a pressured position (a position indicated by a phantom line in
FIG. 1
) to separate the press roller
56
from the outer peripheral wall
50
a
of the printing drum
50
, and a cleaning roller
70
which is selectively brought into contact with the press roller
56
to avoid ink from being adhered to the press roller
56
or to remove adhered ink from the press roller
56
. The press roller
56
functions to move between the pressured engagement position and the separated position in association with rotation of the printing drum
50
during the printing operation such that, during transit of the print sheet
45
, which serves as a print medium, transferred in synchronism with rotation of the printing drum
50
, the press roller
56
remains in the pressured engagement position and, during other operating phase (i.e., during non-transit of the print sheet
45
), the press rollers
56
remains in the separated position.
With such a structure, clamping the leading edge of the stencil sheet
20
′, which is transferred from the upstream stencil making section
2
, with the clamping base
51
, while permitting rotation of the printing drum
50
under the clamped state of the stencil sheet
20
′ allows the stencil sheet
20
′ to be wound around and mounted to the outer periphery
50
a
of the printing drum
50
. When this occurs, the print sheet
45
, which is transferred in synchronism with the rotation of the printing drum
50
, is brought into pressured contact with the stencil sheet
20
′ of the printing drum
50
with the action of the press roller
56
, allowing ink to be transferred through the perforated area of the stencil sheet
20
′ onto the lower surface (the other one surface) of the print sheet
45
to reproduce a desired image thereon.
Paper Feed Section
The paper feed section
6
is constructed of a paper feed tray
57
on which a stack of the print sheets
45
, which serve as printing media, is placed, a primary paper feed roller pair
58
for moving only one print sheet
45
from the uppermost position of the stack of the print sheets
45
in the paper feed tray
57
, and a secondary paper feed roller pair
59
for transferring the print sheet
45
, which is transferred with the paper feed roller pair
58
, to an area between the printing drum
40
and the press roller
46
in synchronism with the rotation of the upstream printing drum
40
. The primary and secondary paper feed roller pairs
58
,
59
are so arranged as to be selectively applied with the drive force of the main motor M by means of respective paper feed clutches (not shown).
Upstream Belt-Conveyer Transfer Unit
The upstream belt-conveyer transfer unit (the upstream transfer unit)
7
function to receive the print sheet
45
discharged from the upstream printing section
4
to transfer the received print sheet
45
to an area in front of the downstream printing section
5
to be fed thereto. The upstream belt-conveyer transfer unit
7
includes a pair of belt stretching members
60
a
,
60
b
, a belt
62
stretched between the pair of belt stretching members
60
a
,
60
b
, an intake box
63
and an intake fan
64
for sucking the leading edge of the print sheet
45
transferred on the belt
62
, and a belt drive unit (not shown) to drive the belt
62
for rotating movement of the belt stretching member
60
a
(or
60
b
). Further, the upstream belt-conveyer transfer unit
7
functions to suck the print sheet
45
to transfer the print sheet
45
due to the movement of the belt
62
per se under a condition that the surface of the print sheet
45
opposed to the previously printed surface is held in contact with the belt
62
.
Downstream Belt-Conveyer Transfer Unit
The downstream belt-CONVEYER transfer unit (the upstream transfer unit)
8
function to receive the print sheet
45
discharged from the downstream printing section
5
to transfer the received print sheet
45
to the sheet discharge section
9
. The downstream belt-conveyer transfer unit
8
includes a pair of pulleys
66
a
,
66
b
, a belt
67
stretched between the pair of pulleys
60
a
,
60
b
, an intake box (not shown) and an intake fan (not shown) for sucking the leading edge of the print sheet
45
transferred on the belt
67
, and a belt drive unit (not shown) to drive the belt
67
for rotating movement of the pulley
66
a
(or
66
b
). Further, the downstream belt-conveyer transfer unit
8
functions to suck the print sheet
45
to transfer the print sheet
45
due to the movement of the belt
67
per se.
Sheet Discharge Section
The sheet discharge section
9
includes a paper receiving tray
71
located in a drop area of the print sheet
45
for allowing the print sheet
45
, which has been printed and is transferred with the downstream belt-conveyer transfer mechanism
8
, to be placed in a stacked state.
Upstream Stencil Disposal Section
The upstream stencil disposal section
10
includes a stencil separating roller pair
72
for receiving the leading edge of the stencil sheet
20
, which has been previously wound on the upstream printing drum
40
with the leading edge being released from the upstream printing drum
40
, and for transferring the stencil sheet
20
, whose clamped state is released, while peeling off the same from the upstream printing drum
40
, and a stencil disposal box
73
for receiving the stencil sheet
20
which is transferred with the stencil separating roller pair
72
.
Downstream Stencil Disposal Section
The downstream stencil disposal section
11
includes a stencil separating roller pair
74
for receiving the leading edge of the stencil sheet
20
′, which has been previously wound on the downstream printing drum
50
with the leading edge being released from the downstream printing drum
50
, and for transferring the stencil sheet
20
′, whose clamped state is released, while peeling off the same from the downstream printing drum
50
, and a stencil disposal box
75
for receiving the stencil sheet
20
′ which is transferred with the stencil separating roller pair
74
.
Printing Drum Unit
Though the aforementioned printing-drum drive escape mechanism
76
is described below in detail, since the printing drum
50
is constructed as a printing drum unit
50
A, a detailed description will begin first from the structure of the printing drum unit
50
A for the purpose for convenience of description. As shown in
FIGS. 2A and 2B
, the printing drum unit
50
A is arranged to be inserted to and to be retracted from a printing drum opening (not shown) of a body frame
77
by means of a printing drum guide rail member (not shown). Further, the printing drum unit
50
A includes a printing drum frame body
78
, a pair of slide support shafts
79
,
79
, the printing drum
50
whose stationary side is fixed to the slide support shafts
79
,
79
, and a drum-rotation power-delivery unit
80
that delivers rotational power to the printing drum
50
.
The printing drum
50
is constructed having a pair of left and right disks (not shown) that are supported on and fixedly secured to the slide support shafts
79
,
79
in a spaced relationship, a pair of annular frames
81
,
81
rotatably supported on the left and right disks, respectively, a stencil clamping base (not shown) which has the stencil clamping segment
51
interconnected at their ends to the annular frames
81
,
81
, respectively, and the screen stretched to cover substantially whole parts of the respective annular frames
81
,
81
in association with the stencil clamping base, with the screen serving as the outer peripheral wall
50
a
. Further, the stationary side of the printing drum
50
is connected to and supports a center shaft
82
with a rotational axis around which the printing drum
50
is rotated while, when the printing drum
50
is mounted to the body frame, the center shaft
82
serves as a center to be mounted.
The drum-rotation power-delivery unit
80
is constructed of a shaft
83
rotatably supported by the stationary side of the printing drum
50
, two gears
84
,
84
connected to end portions of the shaft
83
, a pair of flange gear units
85
,
85
formed on respective outer peripheries of the left and right annular frames
81
,
81
, and a drum-side input drive coupling section
86
fixed to a distal end of the shaft
83
. A frame-side output drive coupling section
87
is connected to the body frame
77
at a position opposing to the drum-side input drive coupling section
86
such that the frame-side output drive coupling section
87
is applied with drive power from the aforementioned main motor M.
Printing-Drum Drive Escape Mechanism
The printing-drum drive escape mechanism
76
includes a drive escape motor
90
fixedly secured to the stationary side of the printing drum
50
, a gear
91
fixed to a rotational axis of the drive escape motor
90
, a cylindrical gear
92
meshing with the gear
91
and rotatably supported on the stationary side of the printing drum
50
, and a threaded rod segment
93
meshing with an internal gear segment of the cylindrical gear
92
and integrally formed on the center shaft
82
. Further, when the drive escape motor
90
is rotated, the cylindrical gear
92
rotates to deliver rotational power to the threaded rod segment
93
, the printing drum
50
, which is slidable with respect to the printing drum frame body
78
, is moved in an axial direction because the leading edge of the center shaft
82
is supported with the body frame
77
.
With such movement, the drum-side input drive coupling section
86
is connected to the frame-side output drive coupling section
87
to assume a mounting position to allow drive power from the main motor M to be delivered to the printing drum
50
to be rotatable as seen in
FIG. 2A
, and drive connection between the drum-side input drive coupling section
86
and the frame-side output drive coupling section
87
is released to assume a drive escape position to interrupt the drive connection between the main motor M and the printing drum
50
as seen in FIG.
2
B.
In
FIGS. 2A and 2B
, also, reference numeral
94
designates a front door which is mounted to a front area of the body frame
77
and which is opened to allow the printing drum unit
50
A to be mounted to or to be removed from the body frame
77
. In an opened phase of the front door
94
, the main motor M is turned off for the security.
Control System Executing Drive Escape Operation
Now, the control system for executing the basic sequence in operational steps of the drive escape operation is described below in detail. As seen in
FIG. 3
, an operation panel of the frame body
77
has a both sides print button
95
and a one side print button
96
, both of which produce output signals to be applied to a control section
97
. Further, the control section
97
is supplied with respective rotating angular positional information of the upstream and downstream printing drums
40
,
50
. The control section
97
controls write-in or read-out of ROM
98
, that stores various program items, and RAM
99
such that, when the print buttons
95
,
96
are operated, the control section
97
executes a flow chart of a sequence of operational steps shown in
FIGS. 4 and 5
. The content of such control is described below in detail with respect to the various operational steps.
(Both Sides Printing Operation)
Now, the stencil making operation and the both sides printing operation of the aforementioned stencil printing machine
1
during a both sides printing mode is described. When selecting the both sides printing mode, the control section
97
checks whether the stencil sheets
20
,
20
′ are mounted to the printing drums
40
,
50
such that, when the stencil sheets
20
,
20
′ are mounted to the printing drums
40
,
50
, the stencil sheets
20
,
20
′ are removed from the respective printing drums
40
,
50
and are disposed into the stencil disposal boxes
73
,
75
.
When terminating the stencil disposal operation, the stencil sheet
20
is thermally perforated with the thermal printing head
22
on the basis of image data of the upper face of the original that is read out in the original read-out operation. Next, the perforated stencil sheet
20
is wound on and mounted to the upstream printing drum
40
to execute a stencil sheet mounting process, thereby completing a stencil sheet mounting operation for the upstream printing drum. Likewise, the stencil sheet
20
′ is thermally perforated with the thermal printing head
32
on the basis of image data of the lower face of the original that is read out in the original read-out operation. Next, the perforated stencil sheet
20
′ is wound on and mounted to the downstream printing drum
50
to execute a stencil sheet mounting process, thereby completing a stencil sheet mounting operation for the downstream printing drum.
Next, when selecting the both-face printing operation by pressing the both-face print button
95
, the control section
97
checks whether the print sheet
45
is placed in the paper feed tray
57
and, in a case where there is no print sheet
45
, the control section
97
implements an error operation. Also, the control section
97
checks whether the stencil sheets
20
,
20
′ are mounted to the printing drums
40
,
50
, respectively, and, in a case where there are no stencil sheets
20
,
20
′ mounted on the respecting printing drums
40
,
50
, the control section
97
executes a non-stencil error operation. Further, the control section
97
checks whether ink remains in ink pools between the squeegee roller
42
and the doctor roller
43
and between the squeegee roller
52
and the doctor roller
53
and, when no ink is found in the ink pools, the control section
97
executes a non-ink error operation. Also, although the control section
97
checks whether the downstream printing drum
50
remains in the drive-connection escaping position, such an operation is described below in detail and, here, the downstream printing drum
50
is described as being positioned in the mounting position.
When clearing all checking items, the main motor M is operated to rotate the respective printing drums
40
,
50
, allowing the print sheet
45
to be fed to the upstream printing drum
40
from the paper feed section
6
in synchronism with rotation of the main motor M. The print sheet
45
is urged against the stencil sheet
20
of the printing drum
40
with the press roller
46
, thereby allowing ink to be transferred onto the upper face of the print sheet
45
to reproduce an ink image thereon. The print sheet
45
, whose upper face is printed, is peeled off from the outer periphery of the printing drum
40
and is conducted to the upstream belt-conveyer transfer unit
7
. The upstream belt-conveyer transfer unit
7
allows the belt
62
to move for transferring the print sheet
45
, whose lower surface is held in contact with the belt
62
, such that the print sheet
45
is fed to the downstream printing drum
50
from the most downstream side of the belt
62
. Thus, the print sheet
45
is urged against the stencil sheet
20
′ of the printing drum
50
with the press roller
56
to allow the lower surface of the print sheet
45
to be transferred with ink image. The print sheet
45
, whose lower face is printed, is peeled off from the outer periphery of the printing drum
50
and is conducted to the downstream belt-conveyer transfer unit
8
. The downstream belt-conveyer transfer unit
8
allows the belt
67
to move for transferring the print sheet
45
from the most downstream side of the belt
67
to the sheet discharge tray
71
. The print sheet
45
thus discharged to the sheet discharge tray
71
is placed in the stacked condition.
(One Side Printing Operation)
Now, the stencil making operation and the one side printing operation of the aforementioned stencil printing machine
1
during a one side printing mode is described. When the one side printing mode is selected, the control section
97
checks whether the stencil sheets
20
,
20
′ are mounted to the printing drums
40
,
50
such that, when the stencil sheet
20
is mounted to the printing drum
40
, the stencil sheet
20
is removed from the upstream printing drum
40
and is disposed into the stencil disposal box
73
. The stencil sheet
20
′ of the downstream printing drum
50
is not disposed and remains in the mounted position.
When terminating the stencil disposal operation, the stencil sheet
20
is thermally perforated with the thermal printing head
22
on the basis of image data of the upper face of the original that is read out in the original read-out operation. Next, the perforated stencil sheet
20
is wound on and mounted to the upstream printing drum
40
to execute the stencil sheet mounting process, thereby completing the stencil sheet mounting operation for the upstream printing drum.
Next, as shown in
FIG. 4
, when the one side printing operation is selected by pressing the one side print button
96
(step S
1
), the control section
97
drives the main motor M to allow the downstream printing drum
50
to be moved to a rotational angular position (i.e., a position shown in
FIG. 6
, wherein a hatched area E designated a perforated area of the stencil sheet
20
′) wherein the print sheet
45
is held in contact with the downstream printing drum
50
at a position except the perforated area of the stencil sheet
20
′ and except the stencil clamping segment
51
(in step S
2
). Then, the drive escape motor
90
is driven to shift the downstream printing drum
50
to the drive escape position shown in
FIG. 2B
(in step S
3
).
Further, the control section
97
checks whether the print sheet
45
is placed in the paper feed tray
57
and, in a case where there is no print sheet
45
, the control section
97
implements a non-paper error operation. Further, the control section
97
checks whether ink remains in ink pools between the squeegee roller
42
and the doctor roller
43
and between the squeegee roller
52
and the doctor roller
53
and, when no ink is found in the ink pools, the control section
97
executes the non-ink error operation.
When clearing all the checking items, the main motor M is operated to rotate only the printing drum
40
, allowing the print sheet
45
to be fed to the upstream printing drum
40
from the paper feed section
6
in synchronism with rotation of the main motor M. The print sheet
45
is urged against the stencil sheet
20
of the printing drum
40
with the press roller
46
, thereby allowing ink to be transferred onto the upper face of the print sheet
45
to reproduce an ink image thereon. The print sheet
45
, whose upper face is printed, is peeled off from the outer periphery of the printing drum
40
and is conducted to the upstream belt-conveyer transfer unit
7
. The upstream belt-conveyer transfer unit
7
allows the belt
62
to move for transferring the print sheet
45
, whose lower surface is held in contact with the belt
62
, such that the print sheet
45
is fed to the downstream printing drum
50
from the most downstream side of the belt
62
.
The print sheet
45
thus fed passes through between the outer periphery
50
a
of the printing drum
50
, which remains in the halted condition, and the press roller
56
which remains in the separated position, to be conducted to the downstream belt-conveyer transfer mechanism
8
.
That is, as shown in
FIG. 6
, since the downstream printing drum
50
remains in the drive escape position, the printing drum
50
is not delivered with rotational power of the main motor M to remain in the stationary condition, while the press roller
56
, which is shifted in association with rotation of the printing drum
50
, remaining in the separated position. Upon receiving the print sheet
45
, which has passed through the space between the printing drum
50
and the press roller
56
, the downstream belt-conveyer transfer unit
8
allows the belt
67
to move for transferring the print sheet
45
to be discharged into the sheet discharge tray
71
in the stacked state.
(Restoring Operation From Drive Escape Mode After One Side Printing Operation)
Now, a description is given to a process for restoring drive connection for the relevant printing drum after the one side printing operation has been terminated. As shown in
FIG. 5
, when the both-face print button
95
is depressed (in step S
4
), the control section
97
checks whether the downstream printing drum
50
remains in the drive escape position (in step S
5
). When the downstream printing drum
50
is found to remain in the drive escape position, the main motor M is driven to allow the upstream printing drum
40
to be shifted to a reference position of the rotating phase with respect to the downstream printing drum
50
(in step S
6
). Subsequently, the drive escape motor
90
is driven to allow the printing drum
50
to move to the mounting position shown in
FIG. 2A
(in step S
7
), thereby completing the operation. The relative rotational phase between the upstream printing drum
40
and the downstream printing drum
50
is precisely adjusted with a rotational phase adjusting unit which is not shown.
(Operation During Drive Escape Mode)
During the aforementioned one side printing mode, the upper surface of the print sheet
45
is transferred with ink in the upstream printing section
4
, with the print sheet
45
, which is transferred with ink, being transferred with the upstream belt-conveyer transfer unit
7
to the position in the downstream printing section
5
. When this takes place, the print sheet
45
passes through the space between the downstream printing drum
50
, which is held stationary, and the press roller
56
, which remains in the separated position, into the downstream belt-conveyer transfer unit
8
, by which the print sheet
45
is further transferred to the sheet discharge section
9
. As a result, it is possible for the stencil sheet
20
′, which has been made in the previous stencil making process, to remain in the mounted state on the printing drum
50
, which remains in the drive escape position, thereby avoiding the need for mounting a non-perforated stencil sheet onto the printing drum
50
. In addition, since the print sheet
45
is fed in the same transfer route as that prepared during the both sides printing mode while the printing drum
50
is not applied with rotational power and remains inoperative, the waste of the stencil sheet
20
′ is avoided and it is unnecessary to prepare an extra transfer unit in another route to transfer the stencil sheet during the one side printing mode, thereby enabling the one side printing operation without deterioration in the quality of ink.
In the illustrated embodiment described above, although the downstream printing drum
50
has been shown and described as being constructed to assume the drive escape position, the upstream printing drum
40
may be constructed so as to assume the drive escape position. That is, in a case where the upstream printing drum
40
is enabled to assume the drive escape position, the print sheet
45
, which is fed from the paper feed section
6
during the one side printing mode, passes through the space between the upstream printing drum
40
, which is held stationary, and the press roller
46
, which remains in the separated position, and is received by the upstream belt-conveyer transfer unit
7
by which the print sheet
45
is further transferred to the position of the downstream printing section
5
to allow the lower surface of the print sheet
45
to be transferred with ink in the downstream printing section
5
, with the print sheet
45
, which has been transferred with ink, being transferred with the downstream belt-conveyer transfer mechanism
8
to the sheet discharge section
9
.
With such a structure discussed above, similarly, the waste of the stencil sheet
20
is avoided and it is unnecessary to prepare an extra transfer unit in another route to transfer the stencil sheet during the one side printing mode, thereby enabling the one side printing operation without deterioration in the quality of ink. Also, both the upstream and downstream printing drums
40
,
50
may be constructed so as to assume the respective drive escape positions to have respective structures one of which can be selected for performing the one side printing operation. With such structures, it becomes possible to freely select the surface (i.e., the upper surface or the lower surface) to be printed in the one side printing mode or the content (i.e., the image content of the upstream printing drum
40
or the image content of the downstream printing drum
50
) to be printed.
In the illustrated embodiment discussed above, also, since the printing drum
50
, which is enabled to shift to the drive escape position, is arranged to assume the drive escape position in the rotating angular position (i.e., the position shown in
FIG. 6
) wherein the printing drum
50
is brought into contact with the print sheet
45
at the area except the perforated area of the stencil sheet
20
′ and except the stencil clamping segment
51
that clamps the stencil sheet
20
′, it is possible for the print sheet
45
to pass without undesired contact with the perforated area of the stencil sheet
20
′, of the printing drum
50
which assumes the drive escape position, and the stencil clamping segment
51
. As a consequence, the print sheet
45
is not adhered with ink and the stencil sheet clamping segment
51
does not become an obstacle for the transfer of the print sheet.
In the illustrated embodiment discussed above, further, since the printing drum
50
, which is enabled to assume the drive escape position, is selected as the printing drum
50
that enables ink transfer to a particular surface, of the print sheet, which becomes the upper surface under a condition where the print sheet
45
is placed on the sheet discharge section, the print sheet
45
is transferred with its printed surface oriented upward, providing an ease of confirmation of the print contents, etc. to effectively prevent the printing operation in the reversed surface of the print sheet
45
.
In the illustrated embodiment discussed above, also, since the printing drum
50
, which is enabled to shift to the drive escape position, is provided in the downstream printing section
5
, the paper feed section
6
is able to feed the print sheet
45
to the upstream printing section
4
at more accurate paper feed timing than that of the upstream transfer unit
7
to perform the printing operation on the print sheet, which has been fed at the accurate paper feed timing, in the upstream printing operation, thereby enabling the printed product to be obtained with a superb performance in the printing position. Also, the presence of the transfer passage in the extended length to the paper receiving tray
71
is effective for preventing the reversed surface of the print sheet
45
from being undesirably printed.
In the illustrated embodiment discussed above, also, the two upstream and downstream printing drums
40
,
50
are rotated in synchronism with one another with rotational power of the main motor M, which is the single drive source, while maintaining the relative rotational phase difference. Thus, in the machine wherein the upstream and downstream printing drums
40
,
50
are both rotated with rotational power of the single drive source, since the printing drum
50
, which remains in the drive escape position, even when the drive source is controlled during the one side printing mode in the same manner as in the both sides printing mode, control in the one side printing mode may be easily performed. Also, in a case where the drive source for the upstream printing drum
40
and the drive source for the downstream printing drum
50
are separately located, control is required in different phases for the respective drive sources in the both sides printing mode and the one side printing mode, respectively.
In the illustrated embodiment discussed above, further, since the press roller
56
is shifted between the pressured position and the separated position relative to the printing drum
50
, which can be shifted to the drive escape position, in association with the rotation of the printing drum
50
, the presence of the printing drum
50
remaining in the drive escape position allows the press roller
56
to remain in the separated position, providing an ease of control for the one side printing operation. In a case where the press roller
56
is not associated in movement with the rotation of the printing drum
50
and the press roller
56
is shifted between the pressured position and the separated position in dependence on the rotational angular position of the printing drum
50
, it is necessary to take a measure for the rotational angular phase for the drive escape position of the printing drum so as to allow the printing drum to perform the drive escape operation at a rotational angular position to render the press roller
56
to assume the separated position.
Still also, in the illustrated embodiment discussed above, although the present invention has been shown and described with reference to a case where the press rotational members are composed of the press rollers
46
,
56
of a sufficiently smaller diameter than those of the printing drums
40
,
50
, the press rotational members may be of members which exert printing pressure against the printing drums
40
,
50
, respectively. For example, the press rotational members may be made of press drums of substantially the same diameter as those of the printing drums
40
,
50
.
Summarizing the above, an advantage of the present invention concerns the printing-drum drive escape mechanism which is able to shift either one of the printing drums of the upstream and downstream printing sections to the drive escape position to disenable the rotation of the either one of the printing drums while retaining the press rotary member, associated with the either one of the printing drums, in the separated position such that, when the one side printing mode is selected, the either one of the printing drums of the upstream and downstream printing sections remains in the drive escape position whereas the press rotary member associated with the either one of the printing drums is rendered to remain in the separated position. Thus, in a case where the downstream printing drum is enabled to assume the drive escape position, one surface of the print sheet is transferred with ink in the upstream printing section during the one side printing mode, with the print sheet, which has been transferred with ink, being transferred through the upstream belt-conveyer transfer unit to the downstream printing section to simply pass the print sheet through the downstream printing drum remaining in the non-rotatable position and the press rotary member remaining in the separated position to be received by the downstream belt-conveyer transfer unit by which the print sheet is then transferred to the sheet discharge section.
In a case where the upstream printing drum is rendered to remain in the drive escape position, further, the print sheet, which has been fed from the paper feed section during the one side printing mode, is allowed to merely pass through between the upstream printing drum remaining in the non-rotatable position and the press rotary member remaining in the separated position to be received by the upstream belt-conveyer transfer unit which then transfers the print sheet to the downstream printing section which transfer ink to the one surface of the print sheet which is then transferred with the downstream belt-conveyer transfer unit to the sheet discharge section.
Therefore, another advantage of the present invention concerns the presence of the printing drum which is enabled to remain in the drive escape position to allow the stencil sheet, which has been previously made, to remain on the printing drum to disenables the need for mounting the non-perforated stencil sheet onto the printing drum while permitting the print sheet to be transferred in the same route as that provided in the both sides printing mode, thereby preventing the waste of the stencil sheet while disenabling the need for providing the extra transfer route specific for the one side printing operation and enabling the one side printing operation without causing a deterioration in the quality of ink.
Also, another advantage of the present invention involves a specific operating condition of the printing drum which is arranged to assume the drive escape position under the condition wherein the print sheet is brought into contact with the printing drum at the area except for the perforated area of the stencil sheet and at the area except for the stencil clamping segment that clamps the stencil sheet. As a result, the print sheet is able to pass through the printing section without contact with the perforated area of the stencil sheet mounted to the printing drum which remains in the drive escape position or with the stencil clamping segment, thereby preventing ink to be adhered to the print sheet while preventing the transfer of the print sheet from being suffered with the stencil clamping segment serving as the obstacle.
Another advantage of the present invention also concerns the printing drum, which is enabled to shift to the drive escape position, allowing the surface, which will face upward in the stacked state on the sheet discharge section, of the print sheet to be transferred with ink, thereby allowing the print sheet to be discharged with its printed surface facing upward to provide an ease of confirmation for the printed content for thereby effectively preventing the reversed surface of the print sheet from being undesirably printed.
Another advantage of the present invention also concerns the printing drum, which is enabled to shift to the drive escape position, of the downstream printing section to allow the paper feed section to feed the print sheet to the upstream printing section at more accurate paper feed timing than that of the upstream transfer unit to perform the printing operation on the print sheet, which has been fed at the accurate paper feed timing, in the upstream printing operation, thereby enabling the printed product to be obtained with a superb performance in the printing position. Also, the presence of the transfer passage in the extended length to the sheet discharge section is effective for preventing the reversed surface of the print sheet from being undesirably printed.
Another advantage of the present invention also concerns the two printing drums of the upstream and downstream printing sections arranged to rotate in synchronism with one another during the both sides printing mode while maintaining the relative rotational angular phase with rotational power of the single drive source such that, in a printing machine wherein both the printing drums of the upstream and downstream printing sections are rotated with rotational power of the single drive source, even when the drive condition of the drive source is controlled during the one side printing mode in the same manner as in the both sides printing mode, the printing drum remaining in the drive escape position is rendered non-operative, thereby providing an ease of control in the one side printing operation.
Still also, another advantage of the present invention concerns the press rotary member, associated with the printing drum which can be shifted to the drive escape position, which is arranged to shift between the pressured position and the separated position in association with the rotation of the aforementioned printing drum, allowing the press rotary member, which opposes to the printing drum, to remain in the separated position by rendering the printing drum, which is able to assume the drive escape position, to remain in the drive escape condition for thereby providing an ease of control in the one side printing operation.
The entire content of a Patent Application No. TOKUGAN 2000-302473 with a filing date of Oct. 2, 2000 in Japan is hereby incorporated by reference.
Although the invention has been described above by reference to a certain embodiment of the invention, the invention is not limited to the embodiment described above. Modifications and variations of the embodiment described above will occur to those skilled in the art, in light of the teachings. The scope of the invention is defined with reference to the following claims.
Claims
- 1. A stencil printing machine selectively carrying out a printing operation in a both sides printing mode and in a one side printing mode, comprising:an upstream printing section including a first printing drum formed with an ink permeable outer peripheral wall adapted to be mounted with a stencil sheet, a first ink supply unit supplying ink to an inner periphery of the first printing drum, and a first press rotary member operative to be held in a pressured position in contact with the outer peripheral wall of the first printing drum to allow ink to be transferred onto one surface of a print medium; a downstream printing section including a second printing drum formed with an ink permeable outer peripheral wall adapted to be mounted with a stencil sheet, a second ink supply unit supplying ink to an inner periphery of the second printing drum, and a second press rotary member operative to be held in a pressured position in contact with the outer peripheral wall of the second printing drum to allow ink to be transferred onto the other surface of the print medium; a paper feed section feeding the print medium to the upstream printing section; and a printing-drum drive escape mechanism operative to shift either selected one of the first and second printing drums into a drive escape position to interrupt rotation of the selected printing drum while retaining either selected one, associated with the selected printing drum, of the first and second press rotary members in a separated position to pass the print medium into a sheet discharge section along the selected printing drum without contact with the selected press rotary member, in the one side printing mode.
- 2. The stencil printing machine according to claim 1, further comprising:an upstream transfer unit transferring the print medium, discharged from the upstream printing section, to be fed to the downstream printing section; and a downstream transfer unit transferring the print medium, discharged from the downstream printing section, to be fed to the sheet discharge section.
- 3. The stencil printing machine according to claim 1, wherein the selected printing drum remains in the drive escape position at a rotational angular position where the print medium is held in contact with the selected printing drum in an area except for a perforated area of the stencil sheet and a stencil clamping area of the selected printing drum.
- 4. The stencil printing machine according to claim 1, wherein the selected printing drum functions to transfer ink to a surface, which serves as an upper surface when placed in a stacked state in the sheet discharge section, of the print medium.
- 5. The stencil printing machine according to claim 1, wherein the second printing drum is selected to be operated with the printing-drum drive escape mechanism in the one side printing mode.
- 6. The stencil printing machine according to claim 1, further comprising a single drive source rotating the first printing drum and the second printing drum in synchronism with each other while retaining a relative rotational angular phase difference in the both sides printing mode.
- 7. The stencil printing machine according to claim 1, wherein the selected press rotary member associated with the selected printing drum is able to shift between the pressured position and the separated position in association with-rotation of the selected printing drum.
- 8. A method of selectively carrying out a printing operation in a both sides printing mode and in a one side printing mode, comprising:providing an upstream printing section including a first printing drum and a first press rotary member operative to shift between a pressured position and a separated position relative to the first printing drum; providing a downstream printing section including a second printing drum and a second press rotary member operative to shift between a pressured position and a separated position relative to the second printing drum; providing a printing-drum drive escape mechanism operative to enable a shift of either selected one of the first and second printing drums into a drive escape position; feeding a print medium to the upstream printing section; and feeding the print medium, which is discharged from the first printing drum of the upstream printing section, to the downstream printing section, wherein, when the one side printing mode is selected, the printing-drum drive escape mechanism is operative to shift either selected one of the first and second printing drums to the drive escape position to render the selected printing drum inoperative and to render the selected press rotary member to remain in the separated position away from the selected printing drum to pass the print medium into a sheet discharge section along the selected printing drum without contact with the selected press rotary member, in the one side printing mode.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2000-302473 |
Oct 2000 |
JP |
|
US Referenced Citations (2)
Number |
Name |
Date |
Kind |
6205918 |
Takahashi et al. |
Mar 2001 |
B1 |
6345573 |
Motoe et al. |
Feb 2002 |
B1 |
Foreign Referenced Citations (2)
Number |
Date |
Country |
8-90893 |
Apr 1996 |
JP |
2000-211231 |
Aug 2000 |
JP |