JPH11129601A - Stencil printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stencil printer for obtaining a smooth sheet deliverability after printing by conveying a sheet by electrostatically attracting it to an electro static attraction belt. SOLUTION: The stencil printer conveys a sheet 19 by electrostatically attracting it by an electrostatic attraction belt 14 provided through a printing unit 11 opposed with a plate cylinder 3 and a pressing means 10 releasably provided at the cylinder 3 toward a sheet delivering unit 12 disposed on the downstream side in a sheet conveying direction (a) from the unit 11. The printer comprises an accelerating conveying means 16 for accelerating the sheet 19 after printing faster than the conveying speed at the time of printing to deliver it to the unit 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a stencil printing machine in which the paper transport speed differs between during printing and after printing.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 9-24604 discloses a plate cylinder,
On the other hand, the paper, which has been printed in the printing section opposed to the press roller provided so as to be able to contact and separate, is separated and discharged from the plate cylinder by the electrostatic attraction of the electrostatic attraction belt charged by the charging means. 2. Description of the Related Art A stencil printing machine that conveys paper toward a paper unit has been proposed. In this stencil printing apparatus, the electrostatic attraction belt is driven to rotate at a constant transport speed, and the electrostatically attracted paper is sequentially discharged onto a paper discharge tray provided at a paper discharge unit.

[0003]

In such a stencil printing apparatus, the printed paper is discharged and sequentially stacked on the discharge tray from the leading end, so that the leading end of the paper is stacked on the discharge tray. The paper does not slip on the torn paper, leaving a problem in the paper discharge property. This problem is particularly remarkable in the case of weak paper. SUMMARY OF THE INVENTION It is an object of the present invention to provide a stencil printer capable of obtaining a smooth paper discharge property of a printed sheet sucked and conveyed by an electrostatic suction belt.

[0004]

According to a first aspect of the present invention, there is provided an electrostatic attraction device in which a plate cylinder and a pressing means provided to be able to contact and separate from the plate cylinder are provided through a printing section facing the plate cylinder. In a stencil printing machine that electrostatically attracts paper with a belt and conveys the paper toward a paper discharge unit located downstream of the printing unit in the paper conveyance direction, the speed of the printed paper is higher than the conveyance speed during printing. Since the sheet has an accelerated conveyance unit that discharges the sheet to the discharge unit at a high speed, the printed sheet is accelerated by the acceleration conveyance unit and discharged vigorously toward the discharge unit.

According to a second aspect of the present invention, in the stencil printing machine according to the first aspect, the accelerating conveying means includes a conveying belt disposed between the electrostatic attraction belt and the sheet discharging section, and the conveying belt being statically moved. Since it has a driving unit that moves at a speed higher than the conveyance speed of the electro attraction belt and a suction unit that generates a suction force on the conveyance surface of the conveyance belt, the printed paper is conveyed from the electrostatic adsorption belt to the conveyance belt. Then, the sheet is accelerated while being adsorbed on the conveyance belt by the suction force acting on the conveyance belt, and is discharged to the sheet discharge section with vigor.

According to a third aspect of the present invention, in the stencil printing machine according to the first aspect, the acceleration / conveying means includes a driving unit for driving the electrostatic attraction belt to rotate, and control for accelerating the driving unit after printing the paper. Means, the printed sheet is accelerated and discharged vigorously toward the discharge section.

According to a fourth aspect of the present invention, in the stencil printing machine according to the third aspect, the electrostatic attraction belt is formed to have an overall length longer than the outer peripheral length of the plate cylinder, and detects an initial position of the electrostatic attraction belt. A belt detecting unit, and a pressing detecting unit for detecting a contact time between the pressing unit and the plate cylinder, wherein the control unit reduces the conveying speed of the electrostatic attraction belt according to a detection signal from the belt detecting unit, and The conveyance speed of the electrostatic attraction belt is kept constant while the detection signal is output from the detection means, and the conveyance speed of the electrostatic attraction belt is increased when the detection signal is no longer output from the pressure detection means. Since the driving unit of the suction belt is controlled, during the contact time between the pressing means and the plate cylinder (during printing), the conveyance speed of the electrostatic suction belt is kept constant, stable printing is performed, and the contact time passes. Detection signal from the belt detection means In until it is output, the paper electrostatic adsorption belt has finished printing becomes accelerated state is conveyed toward the sheet discharge portion is accelerated.

According to a fifth aspect of the present invention, in the stencil printing apparatus according to any one of the first to fourth aspects, charging means for charging the electrostatic attraction belt on the upstream side of the printing unit in the sheet transport direction is provided. The static electricity removing means for removing electricity from the paper and the electrostatic attraction belt, which is disposed downstream of the printing unit in the paper transport direction with respect to the printing unit, is disposed. The paper and the electrostatic attraction belt that have been electrostatically attracted and conveyed to the printing unit and have passed through the printing unit are de-electrified by the static elimination means and deprived of the electrostatic attraction force.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A stencil printing apparatus according to the present invention
An ink supply device for a plate cylinder provided with an opening portion and a non-opening portion, on which a plate-made master is wound on the outer peripheral surface, and an ink supply device for supplying ink to the wound plate-made master. The pressing means is provided so as to be able to contact and separate at a position opposed to the printing section, and the interval between the plate cylinder and the pressing means is a printing section. Printing is performed on paper by pressing the paper. In this stencil printing apparatus, a paper is electrostatically attracted, and an electrostatic attraction belt, which is driven to rotate in synchronization with the rotation of the plate cylinder, is arranged so as to pass through a printing unit, and the printed paper is transported at the time of printing. Is also provided with an accelerated conveying means for increasing the speed and discharging the sheet to the sheet discharge section. For this reason,
The conveying force for the printed sheet is increased, and the sheet is accelerated and conveyed toward the sheet discharge section, and the sheet slides on the sheet stacked on the sheet discharge tray provided in the sheet discharge section.

When the electrostatic attraction belt is arranged so as to pass over the printing unit between the paper feeding unit and the paper discharging unit with the printing unit as a boundary, the electrostatic attraction belt causes the electrostatic attraction belt to move from the paper feeding unit to the printing unit. Then, a transport path for the paper that reaches the paper discharge section through the printer is formed. This is preferable because the paper fed from the paper feeding unit can be sufficiently electrostatically attracted to the electrostatic attraction belt before reaching the printing unit, and the transportability and ingress of the paper to the printing unit are stabilized. . When the paper is transported in the paper transport direction, the electrostatic attraction belt and the attraction surface of the paper expand with the transport, the electrostatic attraction between the paper and the electrostatic attraction belt increases, and the paper at the printing unit The separation between the plate cylinder and the plate cylinder is improved.

There are two types of electrostatic attraction belts, an insulator and a medium resistance. The insulator electrostatic adsorption belt has a volume resistance of 10 ¹³ Ωcm or more, and is made of a resin such as polyimide, polyethylene terephthalate, polyester, polyacetal, polypropylene, vinyl chloride, styrene, urethane, polyethylene, polycarbonate, polytetrafluoroethylene, or the like. Alternatively, a material formed by depositing a conductive metal on the surface of these resins or bonding them with an adhesive may be used. In an insulating electrostatic attraction belt, dielectric polarization occurs when one of the positive and negative charges is injected by applying a voltage, and the paper and the electrostatic attraction belt are charged to + and-, respectively, and are attracted. Is done. Alternatively, the non-uniform electric field is formed by alternately injecting + and-charges by changing the polarity of the applied voltage and forming an alternating electrostatic pattern of + and-charges on the insulating electrostatic attraction belt. The energy of the electric field may be reduced by bringing the sheet of insulating material closer to the electric field, and the sheet of insulating material may be attracted by the attracting force generated at this time.

A medium resistance electrostatic attraction belt has a volume resistance of 1
In 0 ⁷ ~10 ¹² Ωcm, the material may include those subjected to fluorine (polyvinylidene fluoride) coating or the like elastic material chloroprene rubber or ethylene propylene rubber (EPDM) and the like. The reason for applying a fluorine (polyvinylidene fluoride) coating is that the outer peripheral surface of the electrostatic attraction belt has a higher resistance than the elastic body, so that the resistance of the belt or paper is reduced at high temperature and high humidity, and the electrostatic attraction belt is applied. The transfer of the electric charge to the paper reduces the generation of adsorption force between the master and the paper on the outer peripheral surface of the plate cylinder where the resistance value changes little, and the paper wraps around the plate cylinder and separates from the plate cylinder. This is because it is effective in preventing a defect. Another reason is that the friction coefficient μ is reduced, so that the contact resistance between the member that comes into contact with the outer peripheral surface of the electrostatic attraction belt and the electrostatic attraction belt is reduced, and the load torque on the driving unit of the electrostatic attraction belt is reduced. To do that.

[0013] As the accelerated conveyance means, a conveyance belt, which is moved at a speed higher than the conveyance speed of the electrostatic attraction belt by the driving unit due to the suction force of the suction means, is moved between the electrostatic attraction belt and the paper discharge unit. When the paper is placed, the paper that has been electrostatically attracted to the electrostatic attraction belt and passed through the printing unit is delivered to the transport belt, and is then accelerated and transported toward the paper discharge unit. This is preferable because the paper is discharged with a high conveyance force.

[0014] Further, when the accelerating / conveying means is constituted by a driving section for rotatingly driving the electrostatic attraction belt and a control means for controlling the accelerating after the printing of the paper, the conveying belt, its driving section and the suction means are constituted. Even if not used, the paper after printing can be accelerated and conveyed toward the paper discharge unit, so that the size and cost of the stencil printing apparatus can be reduced, which is preferable.

The overall length of the electrostatic attraction belt is preferably longer than the outer peripheral length of the plate cylinder. The initial position of the electrostatic attraction belt is detected by belt detecting means, and the contact time between the pressing means and the plate cylinder is detected by pressing. Detect by means. The control means reduces the conveying speed of the electrostatic attraction belt when a detection signal is issued from the belt detecting means, and keeps the conveying speed of the electrostatic attraction belt constant while the detection signal is output from the pressing detecting means. When the output of the detection signal from the pressure detecting means is stopped, the driving unit is controlled to increase the conveyance speed of the electrostatic attraction belt. It is preferable because it can be conveyed toward.

As the pressure detecting means, there is a means comprising a photo interrupter and a shielding plate. The shielding plate is a member interlocked with the contact / separation operation of the plate cylinder, its rotating shaft, and pressing means so that the non-opening portion of the outer peripheral surface of the plate cylinder passes between the photo interrupters while passing through the printing unit. Or a shield plate is attached to an actuator such as an electromagnetic solenoid that performs the contact / separation operation of the pressing means, and only when this actuator is driven and the non-opening portion on the outer peripheral surface of the plate cylinder passes through the printing unit. , May be located between the photo interrupters.

As the belt detecting means, a reflection type or transmission type optical sensor can be used. It is desirable to provide an initial position detecting unit such as an opening or a bar code on the electrostatic attraction belt according to the sensor to be used in order to obtain the initial position of the electrostatic attraction belt.

When the printed paper is accelerated and conveyed by using the conveying belt, there is no problem if the driving unit of the electrostatic attraction belt and the driving unit of the plate cylinder of the electrostatic belt conveying device are shared. When controlling the driving unit of the electrostatic attraction belt to accelerate and discharge the printed paper, it is preferable that the driving units of the plate cylinder and the electrostatic attraction belt are individually controlled independently.

In the case where a plurality of plate cylinders for winding a pre-made master are provided, the plate cylinders are arranged in series between the sheet feeding section and the sheet discharging section along the sheet conveying direction, and different plate cylinders are provided. Supplying the color inks enables multicolor printing. In this case, after printing is completed in the printing section between the plate cylinder located at the most downstream side and the pressing means, the speed of the electrostatic suction belt is increased, or the speed between the discharge section and the electrostatic suction belt is increased. A conveyor belt that acts on the suction belt may be disposed in the printer, and the conveyor belt may be driven to rotate at a higher speed than the electrostatic attraction belt.

As a charging means for charging the electrostatic attraction belt, a non-contact type using a charger for performing corona discharge using a discharge wire as a discharge member represented by a corotron type or a scorotron type, a roller, There is a contact type using a roller or a brush as a discharging member such as a charging type or a conductive brush type.

The non-contact type charging means is preferable in that the discharge current flows to the casing supporting the discharge wire and the discharge efficiency is not so good, but the current density is high and stable charging can be obtained. Considering the discharge efficiency, it can be said that the contact type in which the electric charge is injected by contacting the electrostatic adsorption belt is preferable. The use of a contact-type charging means is preferable in terms of improving the office environment because the generation of ozone due to discharge in air is extremely small.

The supply of the electric charge to the discharge member is performed from a high voltage power supply such as a constant voltage power supply or a constant current power supply. The constant voltage power supply is
Since the discharge voltage is constant, it is preferable in that the withstand voltage of the power supply and the discharge member can be easily designed. The constant current power supply is preferable in terms of stabilizing the surface potential of the electrostatic attraction belt because the discharge current hardly changes even when there is a change in the discharge environment such as atmospheric pressure and humidity, unlike the constant voltage power supply. Further, when a non-contact type charging means is used, even if the current and voltage on the high voltage power supply side are controlled to be constant, the charging of the electrostatic attraction belt may become uneven. It is preferable to detect the charged state (surface potential) and perform feedback control to the high voltage power supply. When each of these charging units is provided on the paper feeding unit side of the printing unit to charge the electrostatic attraction belt, the paper fed from the paper feeding unit is sufficiently applied to the electrostatic attraction belt before reaching the printing unit. It is preferable because it can be electrostatically attracted.

In order to separate the printed paper from the electrostatic attraction belt, a discharging means for removing the charge (charge) between the printed paper and the electrostatic attraction belt is provided closer to the paper discharge unit than the printing unit. It is good to provide. As the static elimination means, a non-contact type in which charge is supplied from the high-voltage power supply described in the charging means to generate corona discharge, or a contact type using a charging roller may be used. This is preferable because there is no contact with the printing surface and there is no rubbing of the printed image. The charge removing means is configured to discharge the charge neutralizing the charge (charge) on the electrostatic attraction belt charged by the charging means.

As the pressing means, for example, JP-A-9-19-1
No. 04158, a well-known impression cylinder, and a press roller made of natural rubber, chloroprene rubber, nitrile rubber, ethylene propylene rubber, butadiene rubber, styrene butadiene rubber, silicon rubber, or the like. The hardness of the press roller is preferably in the range of rubber hardness of 20 to 70 degrees (according to JIS-A hardness meter).

The contact and separation operations of the press roller and the impression cylinder with respect to the plate cylinder are mechanically performed by using a cam that is rotationally driven in synchronization with the rotation of the plate cylinder, or an electromagnetic mechanism that is driven only during printing. It is preferable to use a contact / separation mechanism that is electrically controlled using an actuator represented by a solenoid.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. In each embodiment, components having the same functions and configurations will be denoted by the same reference numerals, and will not be described again. Omit as much as possible.

(First Embodiment) Plate making to which the present invention is applied,
The basic operation of the digital stencil printing apparatus integrated with printing will be described, and then the configuration and operation of each unit will be described in detail. When the stencil printing start key 73 provided on the operation panel 70 serving as the operation unit shown in FIG. 6 is pressed, the stencil printing machine peels the used master previously used from the outer peripheral surface 3a of the plate cylinder 3 shown in FIG. The plate discharging process and the plate making and feeding process are performed in parallel.

In the plate making and plate feeding step, a master is made by the plate making and plate feeding device 2 in accordance with a document image read by the document reading device 1 provided at the upper portion of the apparatus, and the plate is fed toward the plate cylinder 3, and the plate-made master is fed. 5 is clamped by a clamper 4 disposed on the outer peripheral surface 3a of the plate cylinder 3, and the plate cylinder 3 is driven to rotate clockwise to be wound on the outer peripheral surface 3a of the plate cylinder 3.

In the plate discharging process, a plate discharging peeling / conveying unit (not shown) is driven, and the plate cylinder 3 is rotated counterclockwise, and the rear end of a used master (not shown) wound around the rotating plate cylinder 3 is discharged. The film is gradually scooped up in the peeling and transporting section and peeled off from the outer peripheral surface 3a of the plate cylinder 3, and the clamper 4 is removed at a predetermined timing.
Is opened and stored in the plate discharging device 18 for compression.

The stencil printing apparatus includes a paper feeding unit 6 and a paper feeding device 8.
Paper 19 is electrostatically attracted to the electrostatic attraction belt 14 of the electrostatic belt conveying device 9 charged by the charging means 13 so that the paper 19 can be brought into contact with and separated from the outer peripheral surface 3a of the plate cylinder 3. The paper is conveyed toward the paper discharge unit 12 through a printing unit 11 facing a press roller 10 serving as a pressing unit provided in the printer. The stencil printing apparatus includes an electrostatic attraction belt 14 at the printing unit 11.
The paper 19 conveyed by the press roller 10 and the plate cylinder 3
And a master 5 with a plate made of ink from the inside of the plate cylinder 3
And transferred to the sheet 19 to print an image. The stencil printing apparatus conveys the printed sheet 19 toward the paper discharge unit 12 while electrostatically attracting the printed paper 19 with the electrostatic attraction belt 14, and releases the electrostatic attraction by the static elimination means 15 in the middle thereof to release the electrostatic attraction. The sheet 19 is separated from the belt 14. The stencil printing apparatus discharges the paper 19 separated from the electrostatic attraction belt 14 to the paper discharge tray 17 by using the acceleration transport means 16 provided on the paper discharge unit 12 side.

The document reading apparatus 1 is a so-called reduction optical system for reading an image from a document, and is a well-known method that reflects light emitted from a light source (not shown) to the document by a plurality of mirror groups and converts the light into an image signal. It has a configuration.

The plate making and feeding apparatus 2 forms a perforated image on an unprinted master by a thermal head (not shown) based on an image signal from the document reading apparatus 1, and uses a cutter (not shown) to form the master on which the perforated image is formed. Cut to length,
It has a well-known configuration in which a master is supplied to the clamper 4 as a master for which one plate has been made.

The plate discharging device 18 scoops up the rear end of a used master (not shown) wound around the plate cylinder 3 with a plate discharging peeling / conveying unit (not shown), peels it off from the outer peripheral surface 3a of the plate cylinder 3, and stores it in the device. A known configuration is employed in which the stored used master is compressed using a compression plate (not shown).

The plate cylinder 3 is for winding the master 5 having the plate made thereon on its outer peripheral surface 3a. As shown in FIG. 2, the plate cylinder 3 is formed of a stainless steel plate in a cylindrical shape. A support is composed of a porous thin plate provided with an opening 3b and a non-opening 3c, and a porous elastic layer made of a mesh screen woven with chemical fibers (not shown) is wound around the porous thin plate. doing. As shown in FIG. 1, the plate cylinder 3 is rotatably supported around an ink supply shaft 43 and is arranged at the center of the stencil printing apparatus. The plate cylinder 3 is rotatable in both forward and reverse directions by a plate cylinder driving unit 94 described later. As shown in FIG. 5, the total length L of the outer peripheral surface 3a of the plate cylinder 3
1 is provided slightly longer than the total usable length of the sheet 19, and printing on one sheet 19 can be completed when the plate cylinder 3 makes one rotation.

Inside the plate cylinder 3, an ink roller 41 for supplying ink to the inner peripheral surface of the plate cylinder 3, and an ink pool 44 arranged in parallel with a slight gap between the ink roller 41 and the ink roller 44 are provided. And an ink supply device 40 having a doctor roller 42 for forming the ink. The ink reservoir 44 is supplied with ink for printing. The ink in the ink reservoir 44 flows along the outer peripheral surface of the ink roller 41 and is supplied to the inner peripheral surface of the plate cylinder 3 in an optimal amount. The amount of the ink supplied to the ink reservoir 44 is measured by an ink amount measuring means (not shown), and the amount of ink fed is controlled by an ink pump (not shown). Emulsion inks are used as the inks used in the examples. The ink roller 41 is formed of a metal such as aluminum,
It is configured to rotate clockwise with the plate cylinder 3 by a gear train (not shown). The ratio of the peripheral speed between the ink roller 41 and the plate cylinder 3 is set to a predetermined value.

Outer peripheral surface 3 located at non-opening portion 3c of plate cylinder 3
As shown in FIG. 2, a clamper 4 for clamping the leading end of the master 5 is provided. Clamper 4
Is provided on the outer peripheral surface 3a of the plate cylinder 3 by a mechanism (not shown) around the clamper shaft 39 so as to be freely opened and closed. The clamper 4 occupies the closed position when the plate cylinder 3 rotates, and opens and closes during plate discharging and when the plate-making master 5 is wound. When the leading end of the master 5 is held by the clamper 4, the plate cylinder 3 is driven to rotate clockwise to rotate the master 5.
Is wound around the outer peripheral surface 3 a of the plate cylinder 3.

As shown in FIG. 1, the paper feeder 8 is closer to the paper feed tray 7 than the printing unit 11, that is, the paper transport direction at the time of the forward rotation indicated by arrow a (hereinafter referred to as "paper transport direction a"). ) Is located upstream. The sheet feeding device 8 sends out the sheets 19 stacked on the sheet feeding tray 7 to the printing unit 11, and includes a call roller 50, a sheet feeding roller pair 51, a sabaki plate 52, and a registration roller pair 53. The call roller 50 and the upper feed roller 51a of the feed roller pair 51 are:
When a numerical value of a desired number of prints is input by a ten key 71 provided on the operation panel 70 and a print start key 72 is pressed, the paper is rotated clockwise at a predetermined timing by a paper feed system driving unit 98 to be described later. In cooperation with the upper roller 51a, the lower feed roller 51b, and the sabaki plate 52, the uppermost sheet 19 stacked on the sheet feed tray 7 is separated and sent toward the registration roller pair 53. The registration roller pair 53 is composed of a registration roller upper 53a that is connected to the plate cylinder driving unit 94 via a mechanism (not shown) and is driven to rotate, and a registration roller lower 53b that is in contact with and opposed to the registration roller. . The registration roller pair 53 is driven to rotate at a timing at which the leading end of the area of the perforated image formed on the plate-making master 5 and the leading end of the sheet 19 coincide with each other in the printing unit 11.

The electrostatic belt conveying device 9 includes a driving roller 59 provided on the paper discharge unit 12 side with respect to the printing unit 11, a driven roller 60 disposed near the registration roller pair 53, a tension roller 28 and a driven roller. 29, and the tension is wound around the electrostatic attraction belt 14 so as to pass through the printing unit 11. The electrostatic attraction belt 14 is an endless belt in which both ends of a single film material having a medium resistance (volume resistance of 10 ⁷ to 10 ¹² Ωcm) are welded to each other.
The charging unit 13 and the charge removing unit 15 easily charge and remove the charge.

Tension roller 28, driven roller 29
Are composed of drum-shaped roller members having the same diameter, and prevent the electrostatic attraction belt 14 from being displaced. The tension roller 28 is disposed below the driving roller 59, and the driven roller 29 is disposed below the driven roller 60. The driving roller 59 and the driven roller 29, and the tension roller 28 and the driven roller 60 are respectively arranged diagonally, and wind the electrostatic attraction belt 14 in a square shape. The driving roller 59 and the driven roller 60 are arranged such that the tangents of the outer peripheral surfaces thereof in the horizontal direction are on the same tangent G.

The driving roller 59 is connected to a plate cylinder driving unit 94 via a well-known power transmission mechanism including a pulley and a belt. The electrostatic attraction belt 14 is driven by the power transmission mechanism and the plate cylinder driving unit 94 such that the peripheral speed V of the outer peripheral surface 14a, which is the conveying speed thereof, is equal to the peripheral speed of the outer peripheral surface 3a of the plate cylinder 3. It has become so. The peripheral speed V is
Print speed.

As shown in FIG. 3, the press roller 10 is rotatably supported by a center shaft 10a on one swing end 56a of a press roller arm 56 provided swingably about a shaft 55. It is provided on the outer peripheral surface 3 a of the body 3 so as to be able to come and go. The press roller 10 has a press roller arm 56.
Is urged toward the outer peripheral surface 3a of the plate cylinder 3 by a tension spring 58 provided on the other swing end side 56b. A cam follower 57 is provided at the swing end 56b of the press roller arm 56. The cam follower 57 presses against the peripheral surface of the fan-shaped press roller cam 54 which rotates in synchronization with the plate cylinder 3 by the action of a tension spring 58.

The press roller cam 54 is rotated in synchronization with the timing of feeding the sheet 19 from the registration roller pair 53 and the rotation of the plate cylinder 3. When the paper 19 is not fed from the pair of registration rollers 53, the press roller cam 54 has a large diameter portion formed by a cam follower 57.
The press roller 10 is separated from the plate cylinder 3. The press roller cam 54 is rotated when the sheet 19 is fed from the pair of registration rollers 53, and the small diameter portion thereof is opposed to the cam follower 57, and the press roller 10 is swung clockwise in FIG. , And is lowered at the timing when the rear end of the sheet 19 passes through the printing unit 11.

With such a configuration, the electrostatic attraction belt 14
In the printing unit 11, the outer peripheral surface of the press roller 10 is constantly pressed against the inner peripheral surface 14 b of the printing unit 11 to form a convex shape toward the outer peripheral surface 3 a of the plate cylinder 3 so that the driving roller 59 and the driven roller 60
And the outer peripheral surface 1 located on the printing unit 11 side
4a constitutes a transport path for the sheet 19.

As shown in FIG. 1, the charging means 13 mainly comprises a charger 65, a high-voltage power supply 66 for charging, and a counter roller 106 forming a counter electrode. As described above, the sheet 19 is disposed on the upstream side in the sheet conveying direction a with respect to the suction section A where the sheet 19 is suctioned by the electrostatic suction belt 14. The charger 65 is provided on the outer peripheral surface 1 of the electrostatic attraction belt 14.
4a. As the charger 65, a non-contact type corotron type that performs corona discharge is employed. As the high-voltage power supply 66, a DC power supply that supplies a charging bias to the charger 65 is used. The opposing roller 106 is rotatable at a position facing the charger 65, and its outer peripheral surface 106a is
In contact with the inner peripheral surface 14b.

As shown in FIG. 1, the static eliminator 15 mainly comprises a static eliminator 67 and a high-voltage power supply 68 for static elimination. The static eliminator 67 is located near the outer peripheral surface of the drive roller 59, and is upstream of the separation unit B where the sheet 19 is separated from the electrostatic attraction belt 14 by the curvature of the drive roller 59 and its own stiffness in the sheet conveyance direction a. Located on the side. As the static eliminator 67, a corotron type that performs corona discharge is employed. As the high-voltage power supply 68, a DC power supply that supplies a neutralization bias having a polarity opposite to that of the charging bias to the neutralizer 67 is used. Alternatively, a bipolar AC power supply may be used as the high-voltage power supply 68.

As shown in FIG. 1, the acceleration transport means 16
The printed paper 19 that is attracted to and conveyed by the electrostatic suction belt 14 is discharged to the paper discharge tray 17, and is disposed between the paper discharge tray 17 and the electrostatic suction belt 14. The accelerating conveyance means 16 includes a porous conveyance belt 84 stretched between a driving roller 82 provided on the sheet discharge tray 17 side and a driven roller 83 provided on the separation section B side, and a suction means as suction means. It mainly comprises a fan 85 and a belt drive motor 62 serving as a drive unit for driving the transport belt 84. The pulley 61 is fixed to the shaft 82a of the driving roller 82. A drive belt 64 is wound around the pulley 61 and a drive pulley 63 fixed to an output shaft 62a of a belt drive motor 62.

The transport belt 84 is rotated by a belt drive motor 62 so that the peripheral speed V1 of the transport surface 84a is higher than the peripheral speed V of the outer peripheral surface 14a of the electrostatic attraction belt 14. It is driven to rotate clockwise. In this embodiment, the outer peripheral surface 14 of the electrostatic attraction belt 14 is
When the peripheral speed V of a is set to 1, the transport surface 8 of the transport belt 84 is
The speed is set by controlling the rotation of the belt drive motor 62 so that the peripheral speed V1 of 4a becomes 1.2 times. Instead of controlling the rotation of the belt drive motor 62, the transport surface 8 of the transport belt 84 is determined by the ratio between the pulley 61 and the pulley 63.
The peripheral speed V1 of 4a may be adjusted. Suction fan 85
Is rotationally driven by a fan driving unit 100, which will be described later, in synchronization with the acceleration transport unit 16 to apply a suction force to the transport surface 84a of the transport belt 84.

A separating claw 86 is provided between the driven roller 83 and the driving roller 59 in proximity to the electrostatic attraction belt 14. As shown in FIG. 2, the separation claw 86 is disposed with a slight gap with respect to the outer peripheral surface 14 a of the electrostatic attraction belt 14, and assists separation of the sheet 19 in the separation unit B, and is conveyed. The wrapping of the incoming paper 19 is prevented.

The conveyor belt 8 located on the paper discharge tray 17 side
A jump platform 87 is disposed above the transport belt 84 in proximity to the transport surface 84a of the transport belt 84, as shown in FIG. The jump table 87 guides the printed paper 19 adsorbed on the transport belt 84 while giving a stiffness above the paper discharge tray 17. The jump table 87 is adjusted by a height adjusting mechanism (not shown) according to the thickness of the paper 19. The distance to the transport surface 84a can be adjusted.

As shown in FIG. 6, the operation panel 70
Numeric keys 71 for setting the number of prints and a print start key 7 for setting activation of each operation leading to a printing process
2, a plate making start key 73 for activating each operation from reading of an image of a document to plate making, plate feeding, and printing as test printing, and a stop for stopping each operation up to a printing process and the like. A key 74, a display device 75 composed of LEDs for displaying the number of prints and the like set by the numeric keypad 71, a display device 76 composed of an LCD for displaying the master of the stencil printing apparatus, a jam of the paper 19, and the like, A clear key 77 for canceling the number of prints and the like set by the ten keys 71 and a reset key 78 for starting a printing operation from the beginning are provided.

The high-voltage power supply 66 for charging and the high-voltage power supply 68 for static elimination are electrically connected to a CPU (Central Processing Unit) 91 constituting control means 89 via a power supply control section 69. The control means 89 includes a CP connected to the power supply 90.
U91, I / O (input / output) port and ROM not shown
It comprises a well-known microcomputer having a (read-only storage device) 92, a RAM (readable and writable storage device) 93, etc., which are connected by a signal bus (not shown). Various keys of the operation panel 70 and each display device are electrically connected to the CPU 91, and a command signal and / or an on / off signal and a data signal are transmitted and received to and from the CPU 91. In the control means 89, the CPU 9
The result of the operation at 1 is temporarily stored in the RAM 93,
The information is read out in a timely manner.

The CPU 91 includes a plate cylinder driving unit 94 including a motor for driving the plate cylinder 3 to rotate, a plate making system driving unit 95 for driving the plate making unit 2, and a plate discharging system driving unit 96 for driving the plate discharging unit 18. Paper feed system drive unit 9 for driving paper feed device 8
8. a fan driving unit 100 that drives the suction fan 85;
And a belt drive motor 62 is electrically connected via a drive circuit 102. The CPU 91 transmits and receives a command signal and / or an on / off signal and a data signal to and from the CPU 91, and controls the entire operation of the stencil printing apparatus, such as the activation, stop, and timing of each unit and the driving unit. doing.

The ROM 92 stores in advance data necessary for operations such as starting, stopping, and timing of the apparatus and each driving unit. Specifically, the plate making start key 73
Is pressed, plate making and plate discharging processes and plate making are performed. When the number of prints is set using the numeric keypad 71 and the print start key 72 is pressed, paper feeding,
A series of printing operation programs in which printing and separation / discharge processes are repeatedly performed for the set number of prints are stored. In this printing operation program, when the plate making start key 73 and the printing start key 72 are pressed down to rotate the plate cylinder 3, the high voltage power supply 66, the high voltage power supply 68 and the belt drive motor 62 are driven.

The operation of the first embodiment will be described, but the plate making operation and the plate discharging operation have been described at the beginning and will not be described here. Will be described.

When the print start key 72 is depressed, each drive unit is driven. Specifically, the plate cylinder driving unit 94 is driven to rotate the plate cylinder 3 clockwise, and the electrostatic attraction belt 14 rotates counterclockwise at the same peripheral speed as the peripheral speed of the plate cylinder 3. Moving. When the plate cylinder 3 rotates, the power supply control unit 69 is driven and the charging device 65 sends the electrostatic attraction belt 1.
4 is supplied with a charging bias to charge the electrostatic attraction belt 14. Since the opposing roller 106 serving as the opposing electrode is disposed opposite to the charger 65, the charging bias from the charger 65 is applied to the electrostatic attraction belt 1 by the action of the opposing electrode.
The belt is attracted to the side 4 and stable belt charging is performed.
When the plate cylinder 3 rotates, the belt drive motor 62 is driven to rotate the conveyor belt 84 in the counterclockwise direction about 1.2 times faster than the electrostatic attraction belt 14, and the fan drive unit 100 is driven. The suction fan 85 rotates,
A suction force is generated on the transport surface 84a of the transport belt 84.

In the sheet feeding device 8, the feeding roller 50 and the sheet feeding roller upper 51a are rotated clockwise in the drawing by the sheet feeding system driving section 98 in synchronization with the rotation of the plate cylinder 3, and the sheet feeding roller pair 51 is rotated. The paper 19 loaded on the paper feed tray 7 is separated one by one by the cooperation of the paper feed tray 7 and the sabaki plate 52, and is sent out to the registration roller pair 53 which is stopped rotating. In the registration roller pair 53, the leading end of the sheet 19 and the outer peripheral surface 3a of the plate cylinder 3
The paper 19 is fed toward the printing unit 11 at a predetermined timing at which the leading end of the perforated image formed on the plate-making master 5 wound on the printing unit 11 matches.

As shown in FIG. 2, when the fed sheet 19 is conveyed to the vicinity of the suction section A, the sheet 19 is attracted by the electrostatic force due to the charge on the electrostatic suction belt 14 already charged by the charger 65. Outer peripheral surface 14a of electrostatic attraction belt 14
It is electrostatically attracted to the upper side and transported toward the printing unit 11.
The electrostatically attracted paper 19 is conveyed toward the printing unit 11 by the movement of the electrostatic attraction belt 14, and the adsorbing area adsorbed on the outer peripheral surface 14 a of the electrostatic attraction belt 14 with this conveyance gradually increases. Expand. Therefore, as the conveyance of the paper 19 to the printing unit 11 progresses, the paper 19 and the electrostatic attraction belt 1
4, the electrostatic attraction force of the sheet 19 increases, and the adsorption state of the sheet 19 is stabilized.

As shown in FIG. 3, when the leading end of the sheet 19 is conveyed to a position near the printing section 11, the press roller 1 placed at a position shown by a two-dot chain line from the outer peripheral surface 3a of the plate cylinder 3
0 is a press roller cam 54 that rotates in synchronization with the plate cylinder 3
The outer peripheral surface 3 of the plate cylinder 3
a, and occupies the pressing position shown by the solid line. Since the paper 19 is sufficiently electrostatically attracted to the electrostatic attraction belt 14 arranged so as to pass through the printing unit 11, the paper 19 smoothly enters the printing unit 11.

The press roller 10 is provided on the outer peripheral surface 3 a of the plate cylinder 3.
Even when the electrostatic attraction belt 14 starts rotating, it is always at the same peripheral velocity in the same direction even when the electrostatic attraction belt 14 starts to rotate, even at the separated position apart from Rotate. For this reason, even if the press roller 10 moves up, the peripheral speeds of the press roller 10 and the electrostatic attraction belt 14 do not change, and the loosening and vibration of the electrostatic attraction belt 14 are prevented.

When the paper 19 enters the printing unit 11, the printing operation is performed as shown in FIG.
As shown in FIG. 5, the ink supplied to the inner peripheral surface of the plate cylinder 3 by the ink roller 41 is diffused by the mesh screen (not shown) through the opening 3b of the plate cylinder 3 by the pressing of the press roller 10, and the plate-making master is formed. 5 is uniformly dispersed by the porous support 5 and transferred to the printing surface 19 a of the paper 19 from the opening of the master film of the plate-making master 5. As a result, an image corresponding to the perforated image of the plate-making master 5 is printed on the sheet 19. Printed paper 19
Is further conveyed toward the downstream side in the sheet conveying direction a. At this time, the sheet 19 is pressed by the press roller 10 against the inner peripheral surface 14b at all times to reduce the slack and vibration. It is sufficiently electrostatically attracted to the attraction belt 14.
The electrostatic attraction belt 14 that has passed through the printing unit 11 is inclined away from the printing unit 11 due to the positional relationship between the press roller 10 and the driving roller 59. For this reason, the paper 19 that has passed through the printing unit 11 is firmly stuck on the electrostatic adsorption belt 14 without being wound around the master 5 on the outer peripheral surface 3 a of the plate cylinder 3 even if there is no separation claw near the plate cylinder 3. The sheet is electroadsorbed and conveyed to the downstream side in the sheet conveying direction a, and good printing without claw marks or the like by the separation claw is performed.

The leading end of the sheet 19 passing through the printing unit 11
As shown in FIG. 7, when the electrostatic attraction belt 14 rotates and reaches just below the static eliminator 67, the electrostatic attraction between the electrostatic attraction belt 14 and the sheet 19 is canceled by the static elimination action. For this reason, the paper 19 and the electrostatic attraction belt 14 sequentially pass under the static eliminator 67, so that the entire surface of the paper 19 and the entire surface of the electrostatic attraction belt 14 have a charge eliminating action.

The paper 19 whose charge has been eliminated by the static eliminator 67
Reaches the separation section B, the electrostatic attraction belt 14 is bent along the curvature due to the diameter of the driving roller 59, so that the paper 19 on the outer peripheral surface 14a of the electrostatic attraction belt 14 has strong stiffness. Of the electrostatic attraction belt 1
Peel from the belt against the bending of No. 4. Further, the leading end of the peeled sheet 19 is guided by the separation claw 86 and the accelerating and conveying means 16 on the downstream side in the sheet conveying direction a.
On the conveyor belt 84.

The paper 19 delivered on the conveyor belt 84
Is conveyed by being attracted to the conveying surface 84a by the suction force acting on the conveying surface 84a of the conveying belt 84 rotating counterclockwise and the frictional force between the sheet 19 and the conveying belt 84. The transport belt 84 rotates counterclockwise at a peripheral speed V1 higher than the peripheral speed V of the outer peripheral surface 14a of the electrostatic attraction belt 14. Therefore, when the trailing edge 19b of the paper 19 passes through the printing unit 11, the transport belt 84
Is increased to the peripheral speed V1 of the transfer surface 84a of the discharge tray 1
7 is conveyed. Therefore, the paper 19 that has been printed and separated from the electrostatic suction belt 14 is suction-conveyed on the conveyance surface 84a of the conveyance belt 84 on which the suction force of the suction fan 85 acts, and is guided to the jump table 87, The paper is separated from the transport belt 84 by the jump table 87 and is discharged onto the discharge tray 17 with vigor. The discharged paper 19 collides with the end plate 17a of the paper discharge tray 17 as shown by a two-dot chain line in FIG. 1, stops its progress, falls freely, and is sequentially stacked on the paper discharge tray 17. .

As described above, the outer peripheral surface 14 a of the electrostatic attraction belt 14 is located between the electrostatic attraction belt 14 and the paper discharge tray 17.
By providing the accelerated conveyance means 16 having the conveyance belt 84 that moves at a peripheral speed V1 higher than the peripheral speed V, the paper 19 after printing can be accelerated and discharged toward the paper output tray 17, Even a sheet having a weak waist is guided to the jump table 87 at a sufficient conveyance speed and is crimped, so that the sheet discharging property is improved. When the paper 19 after printing is accelerated and discharged, the discharge time is shortened, so that the printing time can be reduced.

(Second Embodiment) In the second embodiment, the outer peripheral surface 14a of the electrostatic attraction belt 14 is printed faster than at the time of printing without using the accelerated conveying means 16 of the first embodiment. The paper 19 is accelerated and conveyed toward the paper discharge tray 17.

As shown in FIG.
Has wound the electrostatic attraction belt 14 between the driving roller 59 and the driven rollers 29 and 60 and the tension roller 28. The drive roller 59 is connected to a forward / reverse rotatable belt drive motor 162 serving as a drive source of the electrostatic attraction belt 14, and is rotatable independently of the plate cylinder 3. A pulley 161 is fixed to the shaft 59a of the drive roller 59, as shown in FIG. A drive belt 164 is wound around the pulley 161 and a drive pulley 163 fixed to an output shaft 162 a of a belt drive motor 162. The belt drive motor 162 is normally driven in synchronization with the rotation of the plate cylinder 3 at the sheet feeding timing of the paper 19, so that the peripheral speed V of the outer peripheral surface 14 a of the electrostatic attraction belt 14 is reduced. The electrostatic attraction belt 14 is driven to rotate at a speed (printing speed) that is the same as the speed, and one sheet 19
Every time printing is completed, the outer peripheral surface 14a of the electrostatic attraction belt 14 is increased to a peripheral speed V2 which is about 1.2 times faster than the peripheral speed V at the time of printing. In this example, the discharge tray 17 is disposed immediately after the separation claw 86. An opening 105 is formed in the electrostatic attraction belt 14 at one end in the width direction.

An electrostatic attraction belt 1 is provided below the charger 65.
Belt H serving as belt detecting means for detecting the initial position of belt H
A P sensor 103 is provided. Belt HP sensor 1
Reference numeral 03 denotes a light transmission type sensor,
When the opening 105 provided in the device is detected, a detection signal is output.

In the vicinity of the press roller 10, as shown in FIG. 10, a printing pressure detecting sensor 107 composed of a photo interrupter serving as a press detecting means for detecting a contact time between the press roller 10 and the plate cylinder 3 is provided. Are fixedly arranged on a base (not shown). In the vicinity of the printing pressure detection sensor 107, a shaft 109 that rotates in conjunction with the contact / separation operation of the press roller 10 is rotatably supported by a bracket (not shown). The shaft 109 has a printing pressure detection sensor 107
The shielding plate 108 that enters the slit 107a is fixed.

The shaft 109 has a press roller 10 as shown in FIG.
When the shield plate 108 is located in the slit 107a as shown by the solid line in FIG. 10 when it is at the separated position shown by the dashed line, and when the press roller 10 moves toward the pressing position shown by the solid line in FIG. As shown by a two-dot chain line, the shield plate 108 rotates in conjunction with the contact / separation operation of the press roller 10 so as to retract from the inside of the slit 107a. In the printing pressure detection sensor 107, the slit 107
When the shielding plate 108 retreats from the position a, a printing pressure detection signal is output.

As shown in FIG. 9, the belt drive motor 16
The slit plate 111 is fixed to the second output shaft 162a. In the vicinity of the belt drive motor 162, a belt speed detection sensor 110 that detects the number of rotations of the drive motor 162 from the rotation of the slit plate 111 is arranged. The belt speed detection sensor 110 is constituted by a known rotary encoder.

The belt HP sensor 103, the printing pressure detection sensor 107, and the belt speed detection sensor 110 are electrically connected to a CPU 191 which is a main part of the control means 189 shown in FIG. The CPU 191 has a ROM 192
, A RAM 193, and a belt drive motor 162 via a power supply 90 and a drive circuit 102. In addition, similarly to the first embodiment, the CPU 191 includes an operation panel 70, a plate cylinder driving unit 94, a plate making and feeding system driving unit 95, a plate discharging system driving unit 96, a sheet feeding system driving unit 98, and a power control unit 69. Are connected to various high-voltage power supplies 66 and 68, respectively. The CPU 191 sends a command signal and / or
Alternatively, an on / off signal and a data signal are transmitted / received to control the entire operation of the stencil printing apparatus, such as the start, stop, and timing of the devices and the drive unit. In particular, here, a detection signal from the belt speed detection sensor 110,
That is, the peripheral speed of the outer peripheral surface 14a of the electrostatic attraction belt 14 is measured from the rotation speed of the belt drive motor 162.

The ROM 192 stores in advance data necessary for operations such as starting, stopping, and timing of the device and each drive unit. Specifically, when the plate making start 73 key is pressed, a plate making and plate discharging process and plate making are performed, and when the number of prints is set with the ten keys 71 and the printing start key 72 is pressed, the same as the plate making is performed. In the process, a series of printing operation programs in which each process of paper feeding, printing, and separation and discharge is repeatedly performed for the set number of prints is stored. In this printing operation program, the plate making start key 73 and the printing start key 72 are depressed and the plate cylinder 3 is pressed.
Is driven to rotate, the high-voltage power supply 66 and the high-voltage power supply 68 are driven, and the belt driving motor 16 is moved so that the outer peripheral surface 14a of the electrostatic attraction belt 14 moves in the counterclockwise direction at the peripheral speed V.
2 is rotationally driven. When a printing pressure detection signal is output from the printing pressure detection sensor 107 during driving of the belt drive motor 162, the outer peripheral surface 14a of the electrostatic suction belt 14 is in the meantime.
The rotation speed of the belt drive motor 162 is kept constant so that the belt moves at the peripheral speed V, and when the printing pressure detection signal is no longer output from the printing pressure detection sensor 107, the outer peripheral surface 14a of the electrostatic suction belt 14 is moved to the peripheral speed V2. When the detection signal is output from the belt HP sensor 103, the peripheral speed V2 of the outer peripheral surface 14a of the electrostatic attraction belt 14 becomes equal to the peripheral speed V. The rotation speed of the belt drive motor 162 is reduced until the speed is reduced, and the deceleration control is performed.

As described above, since the acceleration and deceleration control of the electrostatic attraction belt 14 is performed between the printing process and the next printing process, the total length L of the electrostatic attraction belt 14 is as shown in FIG.
It is necessary to make the outer circumferential surface 3a of the plate cylinder 3 longer than the total length L1.

The operation of the second embodiment will be described. However, the plate making operation and the plate discharging operation are omitted since they are described in the first embodiment. The operation up to paper discharge will be described.

When the print start key 72 is pressed, the plate cylinder drive unit 94 and the belt drive motor 162 are driven,
The plate cylinder 3 rotates clockwise and the electrostatic attraction belt 14 rotates counterclockwise at a peripheral speed V. When the plate cylinder 3 rotates, the power supply control unit 69 is driven to drive the charger 65.
Then, a charging bias is supplied to the electrostatic attraction belt 14 to charge the electrostatic attraction belt 14.

The sheet feeding device 8 is driven by the sheet feeding system driving section 98 in the same manner as in the first embodiment, and separates the sheets 19 stacked on the sheet feeding tray 7 one by one to form a pair of registration rollers 53.
Send to In the registration roller pair 53, the printing unit 11 prints the sheet 19 at a predetermined timing when the leading end of the sheet 19 and the leading end of the perforated image of the plate-making master 5 wound on the outer peripheral surface 3a of the plate cylinder 3 match. Paper is fed toward 11.

As shown in FIG. 9, when the fed paper 19 is transported to the vicinity of the suction section A, the paper 19 is attracted by the electrostatic force of the charge on the electrostatic suction belt 14 already charged by the charger 65. Outer peripheral surface 14a of electrostatic attraction belt 14
It is electrostatically attracted to the upper side and transported toward the printing unit 11.
The electrostatically attracted paper 19 is conveyed toward the printing unit 11 by the movement of the electrostatic attraction belt 14, and the adsorbing area adsorbed on the outer peripheral surface 14 a of the electrostatic attraction belt 14 with this conveyance gradually increases. Expand. Therefore, as the conveyance of the paper 19 to the printing unit 11 progresses, the paper 19 and the electrostatic attraction belt 1
4, the electrostatic attraction force of the sheet 19 increases, and the state of adsorption of the paper 19 is stabilized.

As shown in FIG. 3, when the leading end of the sheet 19 is conveyed to the vicinity of the printing unit 11, the press roller 1 placed at a position shown by a two-dot chain line from the outer peripheral surface 3a of the plate cylinder 3
0 is a press roller cam 54 that rotates in synchronization with the plate cylinder 3
The outer peripheral surface 3 of the plate cylinder 3
a, and occupies the pressing position shown by the solid line. Then, the shaft 109 shown in FIG. 10 is rotated clockwise, the shielding plate 108 is retracted from the slit 107a, and the printing pressure detection signal is output. Since the paper 19 is sufficiently electrostatically attracted to the electrostatic attraction belt 14 arranged so as to pass through the printing unit 11, the paper 19 smoothly enters the printing unit 11.

When the printing pressure detection signal is output, the rotation of the belt drive motor 162 is kept as it is, and the outer peripheral surface 14a of the electrostatic attraction belt 14 is maintained at the peripheral speed V, which is the printing speed, in the paper transport direction a. Go to When the paper 19 enters the printing unit 11, as shown in FIG. 4, the ink supplied to the inner peripheral surface of the plate cylinder 3 is pressed by the press roller 10 to open the hole 3 b of the plate cylinder 3, a mesh screen (not shown). Is transferred to the printing surface 19a of the sheet 19 from the opening of the master film of the plate-making master 5. As a result, an image corresponding to the perforated image of the plate-making master 5 is printed on the sheet 19. The printed sheet 19 is further transported downstream in the sheet transport direction a.

The electrostatic attraction belt 14 that has passed through the printing unit 11
Is inclined away from the printing unit 11 due to the positional relationship between the press roller 10 and the drive roller 59. For this reason, the paper 19 that has passed through the printing unit 11 is firmly attached to the electrostatic attraction belt 14 without being wound around the plate-making master 5 on the outer peripheral surface 3 a of the plate cylinder 3 even if there is no separation claw near the plate cylinder 3. Is electrostatically attracted and conveyed to the downstream side in the paper conveying direction a,
Good printing without claw marks due to the separation claw is performed.

When printing proceeds and the clamp 4 of the plate cylinder 3 approaches the printing section 11, the press roller 10 descends from the pressing position shown by the solid line to the separation position shown by the two-dot chain line. The shielding plate 108 shown in FIG.
07a. Then, the printing pressure detection sensor 107
As shown in FIG. 12, the CPU 191 increases the rotation speed of the belt drive motor 162 and controls the acceleration until the outer peripheral surface 14a of the electrostatic attraction belt 14 reaches the peripheral speed V2 as shown in FIG. You. Electrostatic suction belt 14
When the outer peripheral surface 14a of the belt 11 reaches the peripheral speed V2, the speed is adjusted by the belt HP sensor 103 to the opening 10 of the electrostatic attraction belt 14.
5 is held until a 5 is detected. That is, one sheet 19
When the rear end 19b of the paper 19 passes through the printing unit 11 as shown in FIG. 13 after the printing on the paper 11 is completed, the printed paper 11 is accelerated by the accelerated electrostatic attraction belt 14 while being transported in the paper transport direction a. Is transported toward the downstream side.

When a detection signal is output from the belt HP sensor 103 as shown in FIG. 12, the rotation speed of the belt drive motor 162 is reduced, and the belt drive motor 162 moves at a peripheral speed V2 (in FIG. 12, represented as a paper discharge speed). Electrostatic suction belt 1
The deceleration control is performed until the outer peripheral surface 14a of the No. 4 reaches the peripheral speed V (print speed).

That is, during the printing time when the press roller 10 and the plate cylinder 3 are in contact, the outer peripheral surface 14a of the electrostatic attraction belt 14 is moved at a constant peripheral speed V to perform stable printing. , The outer peripheral surface 14a of the electrostatic attraction belt 14 is accelerated to the peripheral speed V2 to apply a strong transporting force to the printed paper 19 electrostatically attracted and accelerated in the paper transport direction a. I do.

In FIG. 12, after the acceleration / deceleration control is performed until the outer peripheral surface 14a of the electrostatic attraction belt 14 reaches the peripheral speed V2 which is the paper discharging speed, a constant speed region of the peripheral speed V2 is provided. Although shown, the acceleration / deceleration control may be performed so that the peripheral speed becomes just V2 until the belt HP sensor 103 is detected, and the paper 19 may be discharged while being accelerated.

The leading end of the sheet 19 passing through the printing unit 11
As shown in FIG. 13, when the electrostatic attraction belt 14 moves and immediately below the static eliminator 67, the electrostatic attraction between the electrostatic attraction belt 14 and the sheet 19 is canceled by the static elimination action. For this reason, the paper 19 and the electrostatic attraction belt 14 sequentially pass under the static eliminator 67, so that the entire surface of the paper 19 and the entire surface of the electrostatic attraction belt 14 have a charge eliminating action. When the paper 19 discharged by the static eliminator 67 reaches the separation portion B, the electrostatic attraction belt 14 is bent along the curvature according to the diameter of the drive roller 59, and therefore, the paper 19 has its own waist strength (printing). The sheet is separated from the electrostatic attraction belt 14 by the elasticity of the belt due to its elasticity. The leading end of the peeled paper 19 is
The sheet is guided above the discharge tray 17 by the separation claw 86. Therefore, the discharged paper 19 on the outer peripheral surface 14a of the electrostatic attraction belt 14 is discharged to the discharge tray 17 in an accelerated state.

The discharged paper 19 collides with the end plate 17a of the paper discharge tray 17 as shown by a two-dot chain line in FIG. Be loaded.

As described above, by controlling the acceleration of the belt drive motor 162 as a driving unit of the electrostatic attraction belt 14 after printing, the peripheral speed of the outer peripheral surface 14a of the electrostatic attraction belt 14 can be made faster than at the time of printing. The paper 19 after printing can be accelerated and discharged toward the paper discharge tray 17, so that the paper discharge performance is improved. Further, even a sheet having a weak stiffness is discharged while being sufficiently accelerated while being adsorbed to the electrostatic attraction belt 14 just below the static eliminator 67, so that the leading edge of the sheet falls down and is turned over, and the sheet is aligned. Nothing goes wrong.

When the paper 19 after printing is accelerated and discharged, the discharge time is shortened, so that the printing time can be reduced. Further, since the transport belt 84, the belt drive motor 62 serving as a drive source thereof, and the suction fan 85 do not need to be provided between the electrostatic suction belt 14 and the paper discharge tray 17 as in the first embodiment, stencil printing is performed. The device is reduced in size and cost.

[0089]

According to the first and second aspects of the present invention, the printed paper is accelerated by the accelerating / conveying means and discharged vigorously toward the paper discharge section. Smooth paper discharge property of printed paper is obtained.

According to the third aspect of the present invention, there is no need to provide a transport belt, a drive unit for the transport belt, and a suction means. Smooth paper discharge property can be obtained.

According to the fourth aspect of the invention, during the contact time between the pressing means and the plate cylinder, the conveying speed of the electrostatic attraction belt is kept constant, and after the contact time, the detection signal is outputted from the belt detecting means. During the period until output, the electrostatic attraction belt is in an accelerating state, and the paper after printing is accelerated and conveyed toward the paper discharge section, so that the electrostatic attraction belt adsorbs while reducing the size and cost. Stable printing can be performed while maintaining the smooth paper discharge property of the conveyed printed paper.

According to the fifth aspect of the present invention, the sheet is sufficiently electrostatically attracted to the electrostatic attraction belt charged by the charging means, conveyed to the printing unit, and the paper passing through the printing unit and the electrostatic attraction belt. Is removed by the static elimination means and deprived of the electrostatic attraction force, so that the paper transporting property and the separability from the plate cylinder as well as the separability from the electrostatic attraction belt are improved. As a result, it is possible to obtain smoother paper discharge while performing stable printing.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a stencil printing apparatus showing a first embodiment of the present invention.

FIG. 2 is an enlarged view showing a schematic configuration of a peripheral portion of the electrostatic belt conveyance device.

FIG. 3 is an enlarged view showing a contact / separation mechanism of a press roller and its operation, and a state before a sheet enters a printing unit.

FIG. 4 is an enlarged view showing a state of a sheet when passing through a printing unit.

FIG. 5 is a diagram showing the relationship between the outer peripheral length of the plate cylinder and the entire length of the electrostatic attraction belt.

FIG. 6 is a block diagram illustrating a configuration of a control unit according to the first embodiment.

FIG. 7 is an enlarged view showing the configuration and operation of the acceleration transport means in the first embodiment.

FIG. 8 is a schematic configuration diagram of a stencil printing apparatus showing a second embodiment of the present invention.

FIG. 9 is an enlarged view showing a configuration of an acceleration transport unit in the second embodiment.

FIG. 10 is an enlarged view showing the configuration and operation of the pressure detecting means.

FIG. 11 is a block diagram illustrating a configuration of a control unit according to a second embodiment.

FIG. 12 is a timing chart showing acceleration and deceleration of a sheet by the control unit of the second embodiment.

FIG. 13 is an enlarged view showing the operation of the acceleration control means of the second embodiment.

[Explanation of symbols]

 3 Plate Cylinder 10 Pressing Unit 11 Printing Unit 12 Discharge Unit 13 Charging Unit 14 Electrostatic Attachment Belt 15 Static Elimination Unit 16, 190 Acceleration Conveying Unit 19 Paper 62, 162 Driving Unit 84 Conveying Belt 84a Conveying Surface of Conveying Belt 85 Suction Unit 89 , 189 Control means 103 Belt detection means 107 Press detection means a Paper transport direction L Total length of electrostatic attraction belt L1 Perimeter of plate cylinder

Claims (5)

[Claims] An image forming apparatus includes: a plate cylinder; and a pressing unit provided so as to be capable of coming in contact with and separating from the plate cylinder. A stencil printing apparatus that conveys the paper toward a paper discharge unit disposed downstream in the paper conveyance direction, and accelerates the paper after printing to a speed higher than the conveyance speed at the time of printing and discharges the paper to the paper discharge unit. Stencil printing machine having 2. The stencil printing apparatus according to claim 1, wherein said acceleration transport means includes a transport belt disposed between said electrostatic attraction belt and said paper discharge section, and said electrostatic attraction to said transport belt. A stencil printing machine, comprising: a driving unit that moves at a speed higher than a belt conveying speed; and a suction unit that generates a suction force on a conveying surface of the conveying belt. 3. A stencil printing apparatus according to claim 1, wherein said acceleration transport means comprises a drive section for rotating and driving said electrostatic attraction belt, and a control means for controlling said drive section to accelerate after printing the paper. Stencil printing apparatus having. 4. A stencil printing apparatus according to claim 3, wherein said electrostatic attraction belt is formed to have an overall length longer than the outer peripheral length of said plate cylinder, and belt detecting means for detecting an initial position of said upper electrostatic attraction belt. And a pressure detecting means for detecting a contact time between the pressing means and the plate cylinder, wherein the control means reduces a transport speed of the electrostatic attraction belt according to a detection signal from the belt detecting means. The conveyance speed of the electrostatic attraction belt is kept constant while the detection signal is output from the pressing detection means, and when the detection signal is no longer output from the pressing detection means, the conveyance speed of the electrostatic attraction belt is increased. A stencil printing machine that controls the driving section so as to speed up. 5. A stencil printing apparatus according to claim 1, wherein said charging means is arranged upstream of said printing section in the paper transport direction and charges said electrostatic attraction belt. A stencil printing machine, comprising: a sheet disposed downstream of a printing unit in a sheet conveying direction;