JP2001322343A - Stencil printing equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stencil printing equipment, with which a favorable printed matter can be obtained even after the once occurrence of 'curling up'. SOLUTION: In the stencil printing equipment, in which a master 5 is wound round the outer peripheral surface of a plate cylinder 12, when a printing paper P winds round the plate cylinder 12 so as to interrupt a printing action, the rotary peripheral speed of the plate cylinder 12 is so constituted as to make faster than the predetermined rotary peripheral speed at printing at the re- starting of the printing action after the removal of the printing paper P.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stencil printing machine in which a master is wound on the outer peripheral surface of a plate cylinder, and a printing sheet is obtained by pressing a printing sheet against the master by pressing means.

[0002]

2. Description of the Related Art Using a plate cylinder made of a porous support cylinder and a laminate-structured master in which a porous support is bonded to a thermoplastic resin film, the thermoplastic resin film surface of the master is heated and melted by a thermal head. After perforating plate making, it is wound around a plate cylinder, an appropriate amount of ink is supplied to the inner peripheral surface of the plate cylinder by ink supply means provided inside the plate cylinder, and printing paper is pressed by pressing means such as a press roller or an impression cylinder. 2. Description of the Related Art A digital thermosensitive stencil printing apparatus that performs printing by transferring ink that has leaked from a plate cylinder opening portion and a master perforation portion onto a printing sheet by pressing the plate cylinder, is well known.

In the stencil printing apparatus described above, the printing paper, to which the ink has been transferred by being pressed against the plate cylinder by the pressing means, rises up from the master wound on the plate cylinder by its own waist, and the paper formed by this lifting up When the tip of the peeling claw is inserted into the space between the plate and the master, it is peeled from the outer peripheral surface of the plate cylinder and discharged. However, if the amount of ink adhering to the paper increases due to reasons such as solid portions in the image formed on the paper or the improvement of the ink fluidity in summer, etc., the paper tends to stick to the plate cylinder and becomes a master. And the insertion of the tip of the peeling claw becomes unstable, which causes a problem called "winding" in which the sheet is not discharged while being stuck to the plate cylinder. In order to prevent the "roll-up", a method is adopted in which a blank portion formed at the leading end of the sheet is made as long as possible to increase the space between the sheet and the master.

[0004]

However, according to the above-mentioned method, however, the margins become small due to slippage of the paper separated in the paper feeding unit, or a plurality of papers are passed at one time, and When the paper is stuck without being peeled, "winding up" occurs. In addition, depending on the image to be formed, a large blank portion cannot be formed at the tip. When "winding up" occurs in this way, usually, the stencil printing machine is automatically stopped, and printing is restarted after the operator performs jam processing.

[0005] Since the paper adhered to the plate cylinder by "rolling up" is adhered to the plate cylinder for a relatively long time until it is removed, a large amount of ink is transferred to the paper and the surface of the master. In addition, the ink transferred to the sheet diffuses on the sheet as shown in FIG. 4 and protrudes to the non-opening portion of the master and adheres thereto. Shown). For this reason, even if printing is resumed after the jam has been cleared and the paper is fed normally, the paper is adhered by the ink that has adhered to the master surface and the ink that has sticked out to the non-opening area. As the force increases, "rolling up" occurs continuously,
The amount of ink adhering to the paper increases, resulting in image defects,
Further, there occurs a problem that "set-off" occurs in which the ink of the previously discharged sheet adheres to the back surface of the next sheet to be discharged. In order to prevent these problems, conventionally, after the jam has been cleared, the image position is moved backward by a vertical moving device or the like, and the paper is passed while the leading edge margin is enlarged, and when the surface condition of the plate cylinder returns to the normal state. Although a method of resuming printing has been adopted in anticipation of this, various problems have occurred such as a large amount of waste paper, troublesomeness, and a long printing time.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a stencil printing apparatus which can solve the above problems and can obtain a good printed matter even after "winding" has occurred once.

[0007]

According to the first aspect of the present invention,
In a stencil printing apparatus that performs printing by winding a master on the outer peripheral surface of a plate cylinder, when printing paper is wound around the plate cylinder, a printing operation is interrupted, and when the printing operation is restarted after removing the printing paper, The rotation peripheral speed of the plate cylinder is set higher than a predetermined rotation peripheral speed during printing.

According to a second aspect of the present invention, in the stencil printing machine according to the first aspect, the increased rotational peripheral speed is gradually returned to the predetermined rotational peripheral speed for each printing.

According to a third aspect of the present invention, there is provided a stencil printing machine in which a master is wound on an outer peripheral surface of a plate cylinder and printing is performed by pressing printing paper against the master by pressing means. When the printing operation is interrupted by wrapping the printing paper around the plate cylinder and the printing operation is resumed after removing the printing paper,
The pressing force of the pressing means is reduced by the pressing force varying means from a predetermined pressing force at the time of printing.

According to a fourth aspect of the present invention, in the stencil printing apparatus of the third aspect, the reduced pressing force is gradually returned to the predetermined pressing force for each printing.

According to a fifth aspect of the present invention, there is provided a stencil printing apparatus for printing a master by winding a master on an outer peripheral surface of a plate cylinder having an ink supply member therein and pressing printing paper against the master by a pressing means. An ink supply member moving means for moving the ink supply member, wherein the printing paper is wound around the plate cylinder, the printing operation is interrupted, and when the printing operation is resumed after removing the printing paper, The ink supply member is moved by a supply member moving means to a position more distant from the pressing means than a predetermined position at the time of printing.

According to a sixth aspect of the present invention, in the stencil printing apparatus of the fifth aspect, the ink supply member that has been moved is gradually returned to the predetermined position for each printing.

[0013]

FIG. 1 is a schematic view showing a main part of a stencil printing apparatus employing an embodiment of the present invention. In FIG. 1, a stencil printing machine 1 includes a stencil conveying unit 2, a printing unit 3, a pair of registration rollers 4, and the like. The plate making / conveying section 2 is a master roll (not shown) that rotatably and detachably supports a core portion 5b of a master roll 5a formed by winding a master 5 in which a thermoplastic resin film and a porous support are bonded together in a roll shape. Support means,
Thermal head 6 for perforating and making the thermoplastic resin film surface of master 5, platen roller 7 for transporting master 5 while pressing master 5 against thermal head 6, master transport roller pair 8 and reversing roller pair 9 for transporting master 5, master 5
And a guide plate 11 for guiding the transfer of the master 5.

The thermal head 6 is pressed against the platen roller 7 by urging means (not shown), and the platen roller 7 is rotated by a stepping motor (not shown). The master transport roller pair 8 and the reversing roller pair 9 composed of the driving rollers 8a, 9a and the driven rollers 8b, 9b pressed against the driving rollers 8a, 9a are rotated by driving means (not shown). The master 5 is pinched and transported. The rotational peripheral speed of the master transport roller pair 8 is slightly higher than the rotational peripheral speed of the platen roller 7, and the rotational peripheral speed of the reversing roller pair 9 is slightly higher than the rotational peripheral speed of the master transport roller pair 8. The master 5 between the platen roller 7 and the master transport roller pair 8 and the master 5 between the master transport roller pair 8 and the reversing roller pair 9 are given predetermined tensions, and are loosened and wrinkled. Is prevented from occurring. The cutting means 10 disposed between the master transport roller pair 8 and the reversing roller pair 9 includes a lower blade 1
0a and an upper blade 10b, and a lower blade 1 which is a fixed blade.
The master 5 is cut by rotating the upper blade 10b, which is a movable blade, with respect to 0a. A guide plate 11 for guiding the master 5 to the printing unit 3 is fixed to a side plate (not shown) of the plate making and conveying unit 2.

A printing unit 3 is provided at the lower left of the plate making and conveying unit 2. The printing unit 3 includes a plate cylinder 12, an ink supply unit 1,
3. It has a press roller 14 as a pressing means, a pressing force varying means 15, and the like. The plate cylinder 12 includes a pair of flanges (not shown) rotatably supported by a support shaft 16 also serving as an ink supply pipe, a porous support plate 12a having an opening 12b attached to a peripheral surface of each flange, and a porous support plate 12a. A plurality of mesh screens (not shown) wound around the outer peripheral surface of the porous support plate 12a.
In the non-opening portion a, a stage portion 17 forming a plane along one generatrix is fixedly provided. A clamper shaft 18a is rotatably attached to the stage 17 made of a magnetic material, and a clamper 18 having a magnet (not shown) that can be magnetically attached to the stage is integrally attached to the clamper shaft 18a. The clamper 18 is opened and closed by opening and closing means (not shown) when the plate cylinder 12 occupies a predetermined position. The plate cylinder 12 is rotationally driven by a main motor 19 fixedly mounted on a printing unit side plate (not shown) so that the number of rotations thereof can be varied steplessly. The plate cylinder 12 is configured to be detachable from the stencil printing apparatus main body together with an ink pack (not shown).

Inside the plate cylinder 12, an ink supply means 13 is provided. The ink supply unit 13 includes a support shaft 16, an ink roller 20 as an ink supply member, a doctor roller 21, an ink supply member moving unit 22, and the like. The ink roller 20 is rotatably supported between a pair of ink roller side plates 23 rotatably supported by the support shaft 16 via a bearing (not shown), and rotates the driving force from the main motor 19 with a gear or a belt. Are transmitted by a driving force transmitting means (not shown) and are rotationally driven clockwise in the drawing. The outer peripheral surface of the ink roller 20 is disposed slightly apart from the inner peripheral surface of the porous support plate 12a, and the porous support plate 12a Are arranged so that the outer peripheral surface thereof and the inner peripheral surface of the porous support plate 12a can be brought into contact with each other. The doctor roller 21 rotatably supported between the ink roller side plates 23 receives the rotational driving force from the main motor 19 by a driving force transmitting means (not shown) such as a gear or a belt, and rotates in the counterclockwise direction in the figure. Is done. The doctor roller 21
The ink whose outer peripheral surface is slightly separated from the outer peripheral surface of the ink roller 20 and which is supplied from the support shaft 16 and forms the ink pool 24 in a wedge-shaped space between the rollers 20 and 21 is supplied to each roller. The ink roller 20 is formed into a thin film when passing through the gap between the ink rollers 20 and 21.
Is supplied uniformly on the outer peripheral surface of

Each ink roller side plate 23 has a distance between
Each of the reinforcing members 25 is integrated by being connected to each other, and a gear portion 23 a is formed on an upper portion of one of the ink roller side plates 23. An ink roller moving motor 26 fixed to a side plate (not shown) fixed to the support shaft 16 is provided near an upper portion of the one ink roller side plate 23.
The output shaft 26a has a gear portion 23a
A worm 27 that meshes with the worm 27 is attached. The operation of the ink roller moving motor 26 is controlled by control means (not shown). The ink roller moving motor 26 and the worm 27 constitute the ink supply member moving means 22. The ink roller 20 is moved between a printing position, which is a predetermined position indicated by a solid line in the drawing, and a separation position separated from the press roller 14 indicated by a two-dot chain line in the drawing, when the ink supply member moving means 22 operates. It is positioned steplessly.

A press roller 14 is provided below the plate cylinder 12. The press roller 14 composed of a rubber roller is rotatably supported between one end of a pair of press roller arms 28, and the other end of each press roller arm 28 is rotatably supported between side plates (not shown) of the printing unit 3. Each is attached to a press roller shaft 29. Further, one end of a pressure arm 30 is attached to the press roller shaft 29 so as to be substantially perpendicular to the press roller arm 28. The pressure arm 30 has a cam follower 31 that is rotatable approximately in the middle thereof, and one end of a tension spring 32 constituting the pressing force varying means 15 is attached to the other end. In the vicinity of the left side of the cam follower 31, a press roller cam 33 having a long diameter portion that can contact the cam follower 31 is provided. The press roller cam 33 is rotationally driven in synchronization with the plate cylinder 12 by a driving means (not shown), and its long diameter portion is a cam follower 31.
When the press roller 14 is separated from the outer peripheral surface of the plate cylinder 12 when the press roller 14 is rotated to a position corresponding to the cam follower 31, the press roller 14 is It is formed in such a shape that it comes into pressure contact with the outer peripheral surface and creates a gap with the cam follower 31. Further, near the right side of the press roller shaft 29, the press roller 14 is separated from the outer peripheral surface of the plate cylinder 12.
(Not shown) is mounted.

A pressing force varying means 15 is provided near the press roller 14. The pressing force variable means 15 includes a tension spring 32, a moving piece 34, a moving screw base 35, a pressing force variable motor 36, and the like. The other end of the tension spring 32 having one end attached to the other end of the pressure arm 30 is attached to a block-shaped moving piece 34 having a screw portion at substantially the center. A moving screw table 35 having a sliding plate 35a having a smooth sliding surface, a screw shaft 35b, and two bearing members 35c rotatably supporting the screw shaft 35b is attached to the main body of the stencil printing machine. A moving piece 34 is slidably disposed on the plate 35a in a state where the screw portion is screwed to the screw shaft 35b. One end of the screw shaft 35b extends outside one of the bearing members 35c, and the end of the screw shaft 35b is connected to the output shaft 3 of the pressing force variable motor 36 via a coupling 37.
6a is connected. With the above-described configuration, the pressing force variable motor 36 operates to rotate the screw shaft 35b, and the moving piece 34 is moved in the left-right direction in the drawing, so that the tension of the tension spring 32 changes and the plate of the press roller 14 The pressing force on the body 12 is varied.

A registration roller pair 4 is disposed on the right side of the press contact portion between the plate cylinder 12 and the press roller 14.
Driving roller 4a and driven roller 4b pressed against it
The registration roller pair 4 consisting of
9 is transmitted by a driving force transmitting member (not shown) to rotate at a predetermined timing synchronized with the plate cylinder 12, and the leading end of the printing paper P sent from a paper feeding unit (not shown) is driven by a driving roller. After temporarily stopping at the nip portion between the roller 4a and the driven roller 4b, the paper is fed between the plate cylinder 12 and the press roller 14.

Based on the above configuration, the first aspect of the present invention will be described below.
An example will be described. In the first embodiment, since the pressing force varying means 15 and the ink supply member moving means 22 are not used, a stencil printing machine without these may be used. When a plate making start key on an operation panel (not shown) of the stencil printing apparatus 1 is pressed, a document image is read by an image reading unit (not shown), and the plate cylinder 12 rotates counterclockwise in the figure at a low speed, and the outer peripheral surface is rotated. The used master wound around is peeled and discarded by a plate discharging means (not shown). After the plate discharging operation is completed, the platen roller 7 is rotated clockwise in the drawing, and the master 5 is fed out from the master roll 5a. The fed master 5 forms a plate making image corresponding to the read document image on the surface of the thermoplastic resin film by the thermal head 6,
The platen roller 7, master transport roller pair 8, and reversing roller pair 9 are fed to the printing unit 3 by rotation, and are transported to the plate cylinder 12 stopped at the plate feeding position and the clamper 18 opened.

When it is determined from the number of steps of a stepping motor (not shown) that drives the platen roller 7 that the leading end of the master 5 has been transported to a predetermined position between the stage section 17 and the clamper 18, the clamper 18 is closed and The plate cylinder 12 is rotated clockwise in the drawing at the same peripheral speed as the master transport speed. When it is determined from the number of steps of the stepping motor that the master for one plate has been transported, the rotation of the platen roller 7, the master transport roller pair 8, and the reversing roller pair 9 is stopped,
The cutting means 10 operates to cut the master 5. The cut master 5 is pulled out of the plate making and conveying unit 2 by the rotation of the plate cylinder 12, and is wound on the plate cylinder 12.

When the plate making and plate feeding operations are completed, the main motor 19 operates to start the plate cylinder 12 rotating at a low speed in the clockwise direction in the figure, and one sheet of printing paper P is fed from a sheet feeding unit (not shown). Separated and fed. After the printing paper P separated and fed is temporarily stopped at the nip portion of the registration roller pair 4, the registration roller pair 4 is driven to rotate at the above-described predetermined timing, so that the plate cylinder 12 and the press roller 14 is fed.
Slightly after the feeding of the printing paper P, the holding of the press roller 14 by the holding mechanism (not shown) is released, and the large-diameter portion of the press roller cam 33 comes off the cam follower 31.
The outer peripheral surface is pressed against the outer peripheral surface of the plate cylinder 12 by the urging force of 2. By this pressing, the printing paper P, the master 5, the mesh screen (not shown), and the porous support plate 12a
The press roller 14 and the ink roller 20 are pressed into contact with each other via the
After the ink supplied to the inside of the master a passes through the opening 12b, the ink is filled in the porous support of the master 5 and transferred to the printing paper P through the perforation formed in the thermoplastic resin film of the master 5. As a result, a so-called printing operation is performed.

The printing paper P on which the printing has been performed is transferred to the printing drum 12.
After being peeled off from the plate cylinder 12 by a peeling claw (not shown) provided in the vicinity of the outer peripheral surface of the printer, the paper is conveyed out of the apparatus by a paper discharge conveying means (not shown) and discharged onto a paper discharge tray (not shown). This series of operations completes the printing operation,
The stencil printing machine 1 is in a printing standby state. Stencil printing machine 1
Is in a print standby state, the printing start key is pressed after the operator sets printing conditions such as the number of prints and the printing speed using keys on an operation panel (not shown), and the main motor 19 is operated. Plate cylinder 1
2 is rotated clockwise in the drawing at a set printing speed which is higher than that at the time of printing, and the printing paper P is continuously fed from a paper feeding unit (not shown) to perform a printing operation. When the set number of prints is exhausted, the stencil printing machine 1 stops operating and returns to the printing standby state.

In the above-described printing, if "winding up" occurs for the reason already described, the stencil printing machine 1 detects a paper jam and automatically stops. This is determined because the print paper P fed from the paper feed unit is not detected within a predetermined time by a sensor provided in a paper discharge unit (not shown). The operator resumes printing by pressing the print start key after removing the printing paper P wrapped around the plate cylinder. At this time, a control means (not shown) provided inside the stencil printing apparatus 1 is a main motor 19.
Is controlled, and the plate cylinder 12 is rotated at a peripheral speed (for example, 100 rotations / minute) higher than the peripheral speed (for example, 90 rotations / minute) corresponding to the set printing speed. This allows
The contact time at the time of printing between the plate-making master 5 wound on the outer peripheral surface of the plate cylinder 12 and the printing paper P is shortened,
The amount of ink transferred from the master 5 on which a large amount of ink has adhered to the printing paper P due to the "roll-up" is optimized, and the sticking force between the master 5 and the printing paper P is reduced. Good printed matter can be obtained even from The control means (not shown) includes the main motor 19
Is rotated at a high speed by a predetermined number (about 10 rotations), and then returned to the set printing speed. FIG. 2 shows the transition of the printing speed (plate cylinder rotation speed) in this example. In the above-described embodiment, when the set printing speed is the highest, the rotational peripheral speed after the occurrence of “winding up” is faster than that, so that the main motor 19 sets the maximum printing speed. What can rotate the plate cylinder 12 at a peripheral speed faster than a high speed is used.

As a modification of the first embodiment, when the printing operation is restarted after the occurrence of "winding", the printing drum 12 is rotated at a peripheral speed (for example, 90 revolutions / minute) corresponding to the set printing speed. After rotating at a high peripheral speed (for example, 100 rotations / minute), the peripheral speed is gradually reduced to a peripheral speed corresponding to the set printing speed (for example, 100 rotations / minute for the first sheet and 98 rotations for the second sheet). / Min, third rotation at 95 rotations / minute, fourth rotation at 92 rotations / minute, and fifth rotation at 90 rotations / minute). According to this configuration, the contact time between the plate cylinder 12 and the printing paper P is gradually increased while gradually decreasing the ink spread on the surface of the master 5 by transferring it to the printing paper P for each printing. Thereby, printing can be performed while making the ink transfer amount and the contact time inversely proportional to each other, and a printed matter having an averaged density and a good density can be obtained even after the occurrence of “roll-up”. FIG. 3 shows the transition of the printing speed in this example.

Next, a second embodiment of the present invention will be described.
In the second embodiment, since the ink supply member moving means 22 is not used, a stencil printing machine having no ink supply member moving means may be used. Also, as the main motor 19,
Plate cylinder 1 with a peripheral speed faster than the highest printing speed set
There is no need to be able to rotationally drive 2. When "winding up" occurs and printing is resumed after the operator performs jam processing, a control means (not shown) provided inside the stencil printing apparatus 1 controls the pressing force variable motor 36.
After moving the moving piece 34 to the right in FIG. 1, the plate cylinder 12 is rotated at a peripheral speed corresponding to the set printing speed. Accordingly, the urging force of the tension spring 32 is reduced, so that the pressing force of the press roller 14 against the plate cylinder 12 is reduced, and the amount of ink that exudes from the plate cylinder 12 when the press roller 14 is pressed against the plate cylinder 12 is reduced. As a result, the amount of ink transferred from the master 5 to the printing paper P is optimized, the sticking force between the master 5 and the printing paper P is reduced, and a good printed matter can be obtained even from the first sheet after printing is resumed. Obtainable. The control means (not shown) rotates the plate cylinder 12 a predetermined number of times with the moving piece 34 positioned at the above-described position, and then returns the moving piece 34 to the initial position to continue printing.

As a modification of the second embodiment, when the printing operation is restarted after the occurrence of "winding", the moving piece 34
After the plate cylinder 12 is rotated while the plate is positioned at the above-described position, the moving piece 34 may be gradually moved to the initial position. According to this configuration, by gradually transferring the ink spread on the surface of the master 5 to the printing paper P for each printing, and gradually decreasing the amount of ink exuding from the plate cylinder 12, the ink is gradually increased. Printing can be performed while making the amount of ink transfer and the amount of ink bleeding inversely proportional, so that a printed matter having an averaged density and a good density can be obtained even after the occurrence of “roll-up”.

Next, a third embodiment of the present invention will be described.
In the third embodiment, since the pressing force varying means 15 is not used, a stencil printing machine which does not have this may be used. The main motor 19 does not need to be capable of driving the plate cylinder 12 to rotate at a peripheral speed higher than the highest printing speed set. When "winding up" occurs and printing is resumed after the operator performs a jam clearing operation, a control means (not shown) provided inside the stencil printing apparatus 1 controls the ink roller moving motor 26.
Is operated to move the ink roller 20 from the solid line position in FIG. 1 to the two-dot chain line position, and then the plate cylinder 12 is rotated at a peripheral speed corresponding to the set printing speed. As a result, the position of the nip between the inner peripheral surface of the plate cylinder 12 and the ink roller 20 deviates from the pressure contact position between the plate cylinder 12 and the press roller 14, and the ink roller 20 is backed up when the press roller 14 presses the plate cylinder 12. By reducing the amount of ink oozing from the plate cylinder 12 due to the displacement, the amount of ink transferred from the master 5 to the printing paper P is optimized, and the sticking force between the master 5 and the printing paper P is reduced. As a result, a good printed matter can be obtained even from the first sheet after printing is resumed. The control means (not shown) rotates the plate cylinder 12 a predetermined number of times with the ink roller 20 positioned at the two-dot chain line position, and then returns the ink roller 20 to the solid line position to continue printing.

As a modification of the third embodiment, when the printing operation is restarted after the occurrence of "winding", the ink roller 20 is positioned at the position indicated by the two-dot chain line in FIG.
After rotating 2, the position of the ink roller 20 may be gradually moved to the solid line position in FIG. According to this configuration, it is possible to perform printing while making the ink transfer amount and the ink bleed amount inversely proportional to each other, as in the second embodiment. Can be obtained.

In each of the above-described embodiments, by controlling the plate cylinder peripheral speed, the plate cylinder pressing force by the press roller, and the ink roller position independently, it is possible to obtain a good printed matter even after "winding up" occurs. Although the configuration which can perform the above is shown, a configuration in which these are combined and controlled may be adopted.

[0032]

According to the first aspect of the present invention, the printing time between the plate-making master wound on the outer peripheral surface of the plate cylinder and the printing paper is shortened, and the ink is rolled up. The amount of ink transferred from the master with a large amount of adhered ink to the printing paper is optimized, the sticking force between the master and the printing paper is reduced, and a good printed matter can be obtained even from the first sheet after printing is resumed. .

According to the second aspect of the present invention, the contact time between the plate cylinder and the printing paper is gradually reduced by transferring the ink spread on the surface of the master to the printing paper for each printing. By gradually increasing, it is possible to print while making the ink transfer amount and the contact time inversely proportional,
Even after the occurrence of "roll-up", it is possible to obtain a printed matter having a good average density.

According to the third aspect of the present invention, the amount of ink oozing out of the plate cylinder when the pressing means and the plate cylinder are pressed against each other is reduced, so that the amount of ink transferred from the master to the printing paper is optimized. At the same time, the sticking force between the master and the printing paper is reduced, and a good printed matter can be obtained even from the first sheet after printing is resumed.

According to the fourth aspect of the present invention, while the ink spread on the surface of the master is transferred to the printing paper every printing, the ink is gradually reduced, and the plate cylinder pressing force by the pressing means is gradually reduced. By gradually increasing the amount of ink exuding from the plate cylinder by increasing it, printing can be performed while making the amount of ink transfer and the amount of ink exuding inversely proportional,
Even after the occurrence of "roll-up", it is possible to obtain a printed matter having a good average density.

According to the fifth aspect of the present invention, the position of the nip between the inner peripheral surface of the plate cylinder and the ink supply member is deviated from the pressure contact position between the plate cylinder and the pressing means, and the ink is supplied when the pressing means presses the plate cylinder. The amount of ink that exudes from the plate cylinder due to the shift of the backup position of the member is reduced, so that the amount of ink transferred from the master to the printing paper is optimized and the sticking force between the master and the printing paper is reduced. Good prints can be obtained even from the first sheet after printing is resumed.

According to the sixth aspect of the present invention, while the ink spread on the surface of the master is transferred to the printing paper for each printing, the ink is gradually reduced, and the inner circumferential surface of the plate cylinder and the ink supply member are reduced. By gradually approaching the nip position to the pressure contact position between the plate cylinder and the pressing means to gradually increase the amount of ink exuding from the plate cylinder, printing can be performed while making the amount of ink transfer and the amount of ink exuding inversely proportional. Thus, it is possible to obtain a printed matter having a good average density even after the occurrence of "roll-up".

[Brief description of the drawings]

FIG. 1 is a schematic view of a main part of a stencil printing apparatus used in an embodiment of the present invention.

FIG. 2 is a diagram illustrating a transition of a printing speed according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating a transition of a printing speed in a modification of the first embodiment of the present invention.

FIG. 4 is a diagram illustrating a state of ink transfer from a master to printing paper after occurrence of “winding”.

FIG. 5 is a diagram illustrating a state of ink transfer from a master to printing paper in a normal state.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stencil printer 5 Master 12 Plate cylinder 14 Pressing means (press roller) 15 Pressing force variable means 20 Ink supply member (ink roller) 22 Ink supply member moving means P Printing paper

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) B41F 33/08 B41L 13/16 B B41L 13/16 13/18 N 13/18 Q B41F 31/02 C B

Claims (6)

[Claims] 1. A stencil printing apparatus for performing printing by winding a master on an outer peripheral surface of a plate cylinder, wherein printing paper is wound around the plate cylinder to interrupt a printing operation.
A stencil printing apparatus, wherein when the printing operation is resumed after the printing paper is removed, the rotational peripheral speed of the plate cylinder is set higher than a predetermined rotational peripheral speed during printing. 2. The stencil printing machine according to claim 1, wherein the increased rotational peripheral speed is gradually returned to the predetermined rotational peripheral speed for each printing. 3. A stencil printing apparatus in which a master is wound on an outer peripheral surface of a plate cylinder and printing is performed by pressing a printing sheet against said master by a pressing means, wherein a pressing force variable for changing a pressing force of said pressing means is provided. Means for printing, when the printing paper is wound around the plate cylinder, the printing operation is interrupted, and when the printing operation is resumed after removing the printing paper, the pressing force of the pressing means is printed by the pressing force variable means. A stencil printing apparatus characterized in that the pressing force is reduced below a predetermined pressing force. 4. The stencil printing apparatus according to claim 3, wherein the reduced pressing force is gradually returned to the predetermined pressing force every time printing is performed. 5. A stencil printing machine in which a master is wound on an outer peripheral surface of a plate cylinder having an ink supply member therein and printing is performed by pressing printing paper against said master by a pressing means. An ink supply member moving means for moving, the printing operation is interrupted by winding the printing paper around the plate cylinder, and when the printing operation is resumed after removing the printing paper, A stencil printing apparatus characterized in that an ink supply member is moved to a position more distant from the pressing means than a predetermined position during printing. 6. The stencil printing apparatus according to claim 5, wherein the moved ink supply member is gradually returned to the predetermined position for each printing.