JPH08310099A - Screen process printer - Google Patents

Abstract

PURPOSE: To form a good printed matter without set-off by providing a porous elastic layer for absorbing a part of ink blotting on a paper while recovering elasticity after a matter to be printed is passed through a nip section formed for a press component. CONSTITUTION: This screen process printer is provided with a plate cylinder 1, a thermal head 9 and a punch processing a master 8 composed of a thermoplastic resin film only, a feed and ejection section 10 for feeding the processed master 8 to the outer peripheral face of the plate cylinder 1 and ejecting the same, an ink feed means 41 for feeding ink on the inner peripheral face of the plate cylinder 1 and a press roller 12 as a press component for pressing a paper 20 to the master 8 and blotting ink on the paper 20. An elastic layer formed on the plate cylinder 1 is constituted of an undersize section and an oversize section as nets composed of a polyester or the like, and a part of ink blotting out is absorbed after passing through a nip section N formed for a press roller 12 while recording elasticity.

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 for perforating a master made of only a thermoplastic resin film, winding the master on a plate cylinder, and printing.

[0002]

2. Description of the Related Art In a stencil printing machine, a thermal head in which fine heating elements are arranged in a line is brought into contact with a master for heat-sensitive stencil, and image data corresponding to a document read by a scanner section of a reading device is provided. While energizing the heating element in a pulsed manner, the master is heated and perforated by transporting the master with a platen roller, and this master is wrapped around a porous support cylinder with multiple layers of resin or metal mesh screens. After being wound around the plate cylinder having the above configuration, the ink is supplied to the inner peripheral surface of the plate cylinder by the ink supply means, and the paper is pressed against the plate cylinder by the press roller through the master, and the holes of the plate cylinder and the master are pressed. Ink is exuded from the perforated part to perform printing.

The above-mentioned master is formed by sticking a thermoplastic resin film having a thickness of 1 to 2 μm and synthetic fibers or Japanese paper fibers or a mixture of Japanese paper fibers and synthetic fibers as a porous and flexible support. It has a laminated structure.

The ink used in the above stencil printer is
W that is hard to evaporate and quickly penetrates and dries when printed and transferred to paper, with water dispersed in oil
/ O type emulsion inks are generally used. This is because when the stencil printing machine is left unused for a long period of time and then printing is restarted, ink is evaporated on the support cylinder of the plate cylinder or mesh screen, or ink is absorbed by the master porous support. This is to prevent a large amount of waste paper from being generated due to the decrease in the amount of ink due to the fraying.

[0005]

When an emulsion ink is used, the transferred ink penetrates inside the printing paper,
It took some time for the transferred ink to become sufficiently dry. In the above apparatus, a master having a laminated structure is used for pressing with a press roller, and the press roller is deformed to press the plate cylinder against the ink roller so that the nip portion becomes a substantially pressing portion. Therefore, there is no area to suck back the ink that has transferred to the paper passing between the press roller and the plate cylinder, and the high ink pressure at the pressing part also works, and when the paper is peeled off from the master. The ink filled in the support was pulled out from the perforated portion of the film and transferred to the paper in large quantities. Therefore, when printing continuously, if the next printing paper is ejected and stacked before the ink on the previous printing paper dries, the ink on the previous printing paper will transfer to the back side of the next printing paper. , A problem called set-off occurs. This set-off is especially when printing a solid image with a large amount of ink transfer, low-speed printing when a large amount of ink is transferred and the image density is high, and the fluidity of the ink deteriorates and ink penetration slows down. It tends to occur in low temperature environment.

Therefore, the plate cylinder is composed of a supporting cylinder having a large number of small holes from the inside thereof, an intermediate screen layer, and an outer surface screen layer in contact with the master, and the outer surface of the supporting cylinder via the intermediate screen layer. Japanese Patent Publication No. 63-59393 discloses a technique in which the mesh value is gradually increased to reach the screen layer to improve the dispersion of ink and prevent a large amount of ink from being drawn out. There is.

However, the Japanese paper fibers serving as the support of the master have large voids, and the ink filled in this support is prevented from being undesirably transferred to the paper when the paper is peeled off from the master. It cannot be done or reduced, and it is inevitable that set-off will occur.

Therefore, the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a stencil printing apparatus which can obtain a good printed matter without set-off.

[0009]

According to the first aspect of the present invention,
Perforating a master consisting essentially of a thermoplastic resin film, winding it on the outer peripheral surface of the plate cylinder, supplying ink from the inner peripheral surface of the plate cylinder, pressing the paper with a pressing member to the master, In a stencil printing apparatus for printing by exuding ink from the master onto the paper, the plate cylinder is a porous support, and at the time of pressing the plate cylinder by the pressing member,
And a porous elastic layer that absorbs a part of the ink that has exuded to the paper while elastically deforming and elastically restoring after passing through the nip portion with the pressing member.

According to a second aspect of the present invention, in the stencil printing apparatus according to the first aspect, the elastic layer is made of a mesh screen, and the inner surface of the plate cylinder goes to the outer surface thereof.
It is characterized in that the mesh value is low.

According to a third aspect of the present invention, in the stencil printing apparatus according to the first aspect, the elastic layer has an opening diverging toward the outside from the support side.

[0012]

In the invention described in claim 1, the elastic layer of the plate cylinder is pressed by the pressing member and elastically deformed so that the ink oozes out onto the paper and is elastically restored after passing through the nip portion with the pressing member. At the same time, it absorbs part of the ink that oozes out onto the paper.

According to the second aspect of the present invention, the mesh screen configured such that the mesh value decreases from the inner peripheral surface of the plate cylinder toward the outer peripheral surface thereof is elastically deformed by being pressed by the pressing member and the ink. Is bleeded onto the paper, and after passing through the nip portion with the pressing member, part of the ink bleeding onto the paper is absorbed while elastically restoring.

According to the third aspect of the invention, the elastic layer having an opening diverging from the support side to the outside is elastically deformed by being pressed by the pressing member, causing the ink to seep out to the paper, and the nip with the pressing member. After passing through the section, it recovers elastically and absorbs a part of the ink that has exuded to the paper.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings. The stencil printing machine shown in FIG.
A thermal head 9 for perforating a master 8 substantially consisting of a thermoplastic resin film; and a plate feeding / discharging section 4 for sending the master 8 thus mastered to the outer peripheral surface of the plate cylinder 1 for discharging the plate.
0, an ink supply unit 41 that supplies ink to the inner peripheral surface of the plate cylinder 1, and a press roller 12 as a pressing member that presses the paper 20 against the master 8 and causes the ink to seep out to the paper 20.
Is provided.

As shown in FIG. 3, the plate cylinder 1 has a cylindrical porous support 1c and a porous elastic layer 42 wound around the outer peripheral surface thereof and elastically deformed when pressed by the press roller 12.
It is fixed to an end plate rotatably supported around an ink pipe 5 which will be described later, and is rotated in the arrow direction shown in FIG. 1 by an appropriate driving means.

The elastic layer 42 is composed of a screen lower portion 1a and a screen upper portion 1b which are made of a net made of resin such as tetron or polyester or metal fiber.
After passing through the nip portion N with the press roller 12, a part of the ink that has exuded while being elastically restored is absorbed. From the lower screen 1a to the upper screen 1b,
The lower screen 1a is set to have a mesh value of 350 mesh, and the upper screen 1b is set to have a mesh value of 300 mesh so that the mesh value becomes low. Note that the mesh values of the lower screen 1a and the upper screen 1b may be the same, and the wire diameter used on the upper screen 1b may be reduced to increase the aperture ratio. This helps reduce the ink transfer resistance on the master 8 side.

When the screen lower portion 1a is pressed by the press roller 12, it elastically deforms as shown in FIG. 5, and after passing through the nip portion N with the press roller 12, elastically restores as shown in FIG. The upper screen 1b also elastically deforms like the lower screen 1a.

As shown in FIG. 4, the plate feeding / discharging section 40 includes a support shaft 8a for rotatably supporting the roll-shaped master 8 and a platen roller for feeding the master 8 to the outer peripheral surface of the plate cylinder 1 while feeding the master 8. 7, a winding shaft 10 that winds the master 8 through the outer peripheral surface of the plate cylinder 1, and a pair of support arms 6 that rotatably support the support shaft 8a, the platen roller 7, and the winding shaft 10. Has been done.

A predetermined braking force is applied to the support shaft 8a so that the master 8 is not unnecessarily paid out during printing. A one-way clutch is connected to the winding shaft 10 to rotate the winding shaft 10 only in the counterclockwise direction in FIG. A drive gear 26 is fixed to the end of the winding shaft 10. An absorbing member 11 that absorbs ink that has exuded from the used master 8 is provided at a position where the widthwise end of the used master 8 wound around the winding shaft 10 is in contact. This absorbing member 11 can prevent ink from scattering. A drive gear 23 is fixed to the end of the shaft of the platen roller 7.

The pair of support arms 6 are formed so as to be detachable from the end plate of the plate cylinder 1, and are rotatably supported around the ink pipe 5. A pair of support arms 6
Is engaged with the plate cylinder 1 at the time of printing and rotates integrally with the plate cylinder 1, and is disengaged from the plate cylinder 1 at the time of plate feeding / discharging, allowing only the plate cylinder 1 to rotate. The pair of support arms 6 detachably supports the support shaft 8a and the winding shaft 10.

At a predetermined plate feeding / discharging position (positions shown in FIGS. 1 and 4), a stepping motor 24 and a plate discharging motor 27, which rotate and drive the above-mentioned driving gears 23 and 26, are arranged. At the time of plate feeding / discharging, both motors drive the drive gears 23, 26 and output shafts 24a of the two motors,
The output gears 25 and 28 fixed to 27a are moved to a position where the output gears 25 and 28 mesh with each other, while the output gears 25 and 28 are moved to a position separated from the drive gears 23 and 26 during printing.

The thermal head 9 is located near the outer peripheral surface of the plate cylinder 1 and at a predetermined plate feeding / discharging position.
It is located at a position opposite to. Thermal head 9
Are oscillated between a position where they are pressed against the platen roller 7 and a position where they are separated from the platen roller 7. The thermal head 9 has a known function of selectively melting and punching the master 8 based on a signal of an image to be printed.

The ink supply means 41 is disposed inside the plate cylinder 1 and is arranged in parallel with the ink roller 2 which supplies ink to the inner peripheral surface of the plate cylinder 1 and a small gap with the ink roller 2. A doctor roller 3 that forms an ink reservoir 4 between the ink roller 2 and an ink pipe 5 that also serves as a rotation center axis of the plate cylinder 1 and supplies ink to the ink reservoir 4.

The shaft of the ink roller 2 is rotatably supported by a side plate fixed to the ink pipe 5, and the plate cylinder is synchronized with the rotation of the plate cylinder 1 by a drive transmission means such as a gear or a belt. It is rotationally driven in the same direction as the rotational direction of 1. An elastic layer made of oil-resistant nitrile rubber, fluororubber, resin, or the like is formed on the surface of the ink roller 2. This elastic layer includes the press roller 12 and the plate cylinder 1.
This helps to reduce the impact noise when the ink roller 2 is brought into contact with the ink roller 2.

The ink is sucked by an ink supply device from an ink pack provided outside the plate cylinder 1 and is supplied from the ink pipe 5 to the ink reservoir 4. There is a gap between the outer peripheral surface of the ink roller 2 and the inner peripheral surface of the plate cylinder 1, and when the press roller 12 contacts the plate cylinder 1 as shown in FIG. Both abut.

Near the lower side of the outer peripheral surface of the plate cylinder 1, the paper 20
A press roller 12 that presses against the plate cylinder 1 to and from the plate cylinder 1, and a registration roller pair 18 that feeds the paper 20 between the plate cylinder 1 and the press roller 12 at a predetermined timing are arranged. . The press roller 12 is made of metal, or a core material such as metal, and hard rubber wound on the surface thereof, and when the paper 20 is pressed against the plate cylinder 1,
In order to widen the contact width between the plate cylinder 1 and the press roller 12, its diameter is set larger than that of the ink roller 2. In addition, the press roller 12 is replaced with the ink roller 2
Instead of directly below the plate cylinder 1, it may be arranged on the downstream side in the rotation direction of the plate cylinder 1.

Between the plate cylinder 1 and the registration roller pair 18, a paper detection sensor 19 which detects the feeding of the paper 20 from the registration roller pair 18 and commands the contact of the press roller 12 with the plate cylinder 1. Is provided.

In the vicinity of the left side of the press roller 12, a paper discharge claw 13 that guides the printed paper 20 in the vicinity of the press roller 12 and guides the peeling, and a paper 20 that is peeled and guided by the paper discharge claw 13 are conveyed. 14 before the roller, 15 after the transport roller
The conveyor belt 16 and the suction fan 31 stretched between
And a fan 17 that blows air between the plate cylinder 1 and the press roller 12 to assist the separation of the sheet 20 from the plate cylinder 1. Conveyor belt 16
Are set to be driven by a motor or the like at a conveying speed higher than the peripheral speed of the plate cylinder 1.

An antistatic agent is applied to the contact surface of the master 1 with the thermal head 9. Here, the master consisting essentially of a thermoplastic resin film, in addition to those in which the master consists of only a thermoplastic resin film, those containing a trace amount of components such as an antistatic agent in the thermoplastic resin film, further, The thermoplastic resin film includes one or more thin film layers such as an overcoat layer formed on both main surfaces, that is, at least one of the front surface and the back surface.

Next, the operation of this stencil printing machine will be described. At the time of feeding and discharging the plate, the plate cylinder 1 is stopped at the position shown in FIG.
The output gears 25 and 28 mesh with the drive gears 23 and 26, respectively, in the direction of the arrow indicated by. Further, the thermal head 9 is pressed against the platen roller 7 via the master 8. Simultaneously with these operations, the pair of support arms 6 causes the plate cylinder 1 to move.
The end plate is disengaged, and only the plate cylinder 1 is allowed to rotate, and the plate supply / ejection standby state is set.

Next, the stepping motor 24, the plate discharge motor 27, and the plate cylinder 1 start to rotate, respectively, and the master 8 is paid out from the support shaft 8a. The heating element of the thermal head 9, which is pressed against the platen roller 7 via the master 8, is selectively heated by the signal of the image to be printed, the master 8 is heat-punched, and a punched image is formed on the master 8. At the same time, the used master 8 is wound around the winding shaft 10. The ink that has exuded from the used master 8 is absorbed by the absorbing member 11.

When the master 8 is wound around a predetermined position on the outer peripheral surface of the plate cylinder 1 (determined by, for example, the number of steps of the stepping motor 24 and the rotation angle of the plate cylinder 1),
The plate feeding / discharging operation is completed, and the plate cylinder 1 stops at the position shown in FIG. The rotations of the stepping motor 24 and the plate discharge motor 27 are stopped, and the output gears 25 and 28 are moved to positions separated from the drive gears 23 and 26, respectively, as shown in FIG.
The end plate of the plate cylinder 1 and the pair of support arms 6 are engaged with each other to enter a print standby state.

When the printing process is started, the sheet 20 is sent toward the registration roller pair 18 by the sheet conveying means, and further, the registration roller pair 18 and the press roller 12 and the plate cylinder are synchronized with the rotation of the plate cylinder 1 at a predetermined timing. It is sent out between 1 and. At this time, the paper detection sensor 19 causes the paper 2
0 is detected, the press roller 12 rises as shown in FIGS. 2 and 3, and the paper 20 is continuously pressed by the master 8 wound around the outer peripheral surface of the plate cylinder 1 to cause elasticity. The layer 42 elastically deforms, the master 8 comes into close contact with the outer peripheral surface of the plate cylinder 1, and the ink is transferred from the perforated portion of the master 8 to the surface of the paper 20. At this time, the ink roller 2 also rotates in the same direction as the rotation direction of the plate cylinder 1 and supplies ink to the inner peripheral surface of the plate cylinder 1. It should be noted that the illustration of the sheet 20 is omitted in FIG. 3 for the sake of simplicity.

After passing through the nip portion N with the press roller 12, the elastic layer 42 has an area Δ as shown in FIGS.
While recovering elastically at A, the excess ink that has exuded is absorbed. In this way, the printed paper 20 is separated from the plate cylinder 1 by the fan 17 and the paper ejection claw 13, is conveyed by the suction conveyance device and is ejected onto the paper ejection tray, and the printing is performed. The press roller 12 separates from the plate cylinder 1 and returns to the initial state, and enters the print standby state.

Next, printing is performed by repeating the steps of printing, feeding and discharging as described above until the set number of prints is reached.

FIG. 7 shows another embodiment. This embodiment differs from the embodiment shown in FIG. 1 only in that an impression cylinder 21 is used instead of the press roller 12. In the figure,
The same members as those in the above-described embodiment are designated by the same reference numerals, and the description thereof will be omitted and only different points will be described.

The impression cylinder 21 is formed so that its diameter is substantially equal to the diameter of the plate cylinder 1 and is arranged around the eccentric shaft 21a in the arrow direction.
It is rotated at the same peripheral speed as the peripheral speed of. A recess 21 b is formed on a part of the outer peripheral surface of the impression cylinder 21 in order to avoid interference with the plate supply / discharge unit 40. The impression cylinder 21 of this recess 21b
A muller claw 22 that holds the leading end of the sheet 20 is provided at the downstream end in the rotation direction of the sheet. The mullet claw 22 is fixed to the shaft 22a and is constantly urged by a spring in the closing direction. The impression cylinder 21 is brought into contact with and separated from the plate cylinder 1 by swinging the eccentric shaft 21a by a swinging means (not shown).

Hereinafter, an operation different from the operation of the above-mentioned embodiment,
That is, only the printing process will be described. When the printing process is started, the sheet 20 is sent toward the registration roller pair 18 by the sheet conveying means, and the registration roller pair 18 causes the sheet 20 to be held between the squatting claws 22 of the impression cylinder 21 at a predetermined timing synchronized with the rotation of the plate cylinder 1. Is inserted. The front end of the paper 20 is held by the muller claw 22, so that the paper 20 is held on the outer peripheral surface of the plate cylinder 1 and the impression cylinder 2.
1 is conveyed to the outer peripheral surface. At this time, the conveyance of the sheet 20 is detected by the sheet detection sensor 19, so that the impression cylinder 2
The eccentric shaft 21a of No. 1 rotates counterclockwise and the impression cylinder 21
Rises and the paper 20 is continuously pressed against the master 8 wound around the outer peripheral surface of the plate cylinder 1 to elastically deform the elastic layer 42,
The master 8 comes into close contact with the outer peripheral surface of the plate cylinder 1 and the master 8
Ink is transferred to the surface of the paper 20 from the perforated portion of the sheet.

At this time, the ink roller 2 also rotates in the same direction as the rotation direction of the plate cylinder 1 to supply ink to the inner peripheral surface of the plate cylinder 1. The printed paper 20 has a mullet nail 22 at a predetermined position.
It is further opened, separated from the plate cylinder 1 by the fan 17 and the paper ejection pawl 13, conveyed by the suction conveyance device, and ejected and stacked on a paper ejection stand (not shown).

FIG. 8 shows another elastic layer 30. Elastic layer 30
Is, for example, soft polyester, polyethylene, vinyl chloride, urethane, silicon, etc., and has a thickness of several tens to several tens.
A sheet having a thickness of 0 μm is used. The elastic layer 30 is formed with an opening 30a that widens toward the outside from the support 1c side by molding or laser.

In this way, the opening 3 that spreads toward the end of the elastic layer 30 is formed.
Forming 0a helps reduce the ink transfer resistance on the master 8 side. The elastic layer 30 is also the elastic layer 42 described above.
Similarly, after passing through the nip portion N with the press roller 12, the excess ink that has exuded is absorbed while elastically restoring in the area ΔA.

[0043]

According to the first aspect of the present invention, the elastic layer of the plate cylinder is pressed by the pressing member and elastically deformed to allow the ink to seep out to the paper and elastically after passing through the nip portion with the pressing member. Since part of the ink that oozes out onto the paper while being restored is absorbed, it is possible to suppress the amount of ink transferred to the paper and prevent deterioration of set-off. Also, in a master consisting essentially of a thermoplastic resin film, since there is no area where ink is accumulated, the movement of the sucking ink at the time of restoration of the elastic layer is fast, and the ink is quickly sucked back and the set-off is greatly done. Will be reduced.

According to the second aspect of the invention, the mesh screen is constructed such that the mesh value decreases from the inner peripheral surface of the plate cylinder toward the outer peripheral surface thereof, and the mesh screen is elastically deformed by being pressed by the pressing member. Bleeds out onto the paper, absorbs part of the ink that bleeds out onto the paper while elastically restoring after passing through the nip part with the pressing member, so that the master side can satisfactorily absorb the ink by restoring the screen etc. Therefore, the amount of ink transferred to the paper can be suppressed, and the set-off can be reduced.

According to the third aspect of the invention, the elastic layer having an opening diverging toward the outside from the support side is elastically deformed by being pressed by the pressing member, causing the ink to seep out to the paper, and the nip with the pressing member. It absorbs part of the ink that oozes out onto the paper while recovering elastically after passing through the section, so that the master side can satisfactorily absorb the ink and the amount of ink transfer to the paper is suppressed, and the set-off is prevented. It can be reduced.

[Brief description of drawings]

FIG. 1 is a side view of a stencil printing machine showing an embodiment of the present invention.

FIG. 2 is a side view of the stencil printing apparatus for explaining a printing operation.

3 is an enlarged side sectional view of a plate cylinder 1 of the stencil printing apparatus shown in FIG.

FIG. 4 is a side sectional view of a main part showing a plate feeding / discharging part of the stencil printing machine shown in FIG.

5 is a conceptual diagram of elastic deformation under the screen of the plate cylinder shown in FIG.

FIG. 6 is a conceptual diagram of restoration under the screen shown in FIG.

FIG. 7 is a side view of a stencil printing machine showing another embodiment of the present invention.

FIG. 8 is a side sectional view showing another elastic layer.

[Explanation of symbols]

 1 plate cylinder 1a screen lower 1b screen 8 master 12 press roller 20 as a pressing member 20 paper 21 pressure cylinder 40 as a pressing member 40 plate feeding / discharging part 41 ink supplying means 42, 30 elastic layer 30a opening N nip part

Claims (3)

[Claims] 1. A master, which is substantially composed of a thermoplastic resin film, is perforated for plate making, is wound on the outer peripheral surface of a plate cylinder, and is supplied with ink from the inner peripheral surface of the plate cylinder by a pressing member. In a stencil printing apparatus that presses a sheet of paper to cause the ink to bleed from the master to the sheet of paper and print, the plate cylinder is elastically deformed when the plate cylinder is pressed by a porous support and the pressing member, A stencil printing apparatus comprising: a porous elastic layer that absorbs a part of the ink that has exuded on the paper while elastically restoring after passing through a nip portion with the pressing member. 2. The stencil according to claim 1, wherein the elastic layer is composed of a mesh screen, and the mesh value becomes lower from the inner peripheral surface to the outer peripheral surface of the plate cylinder. Printing device. 3. The stencil printing apparatus according to claim 1, wherein the elastic layer has an opening that widens toward the outside from the support side.