JP2001058457A - Stencil printing equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stencil printing equipment, in which the plate-making starting position for a master can be specified with respect to the phase of a plate cylinder. SOLUTION: This device is equipped with a plate cylinder 9 having a master engaging means 13, a master storing means 2 for storing a master 1, a plate- making means 3, a cutting means 7, a phase sensing means 14 for sensing the phase of the plate cylinder 9, a controlling means for actuating the plate-making means 3 on the basis of a sensing signal sent from the phase sensing means 14 and a constant torque rotating means 19 for rotating the plate cylinder under the predetermined torque at the winding of the master 1 around the plate cylinder 9. After the engagement of the master 1 with a master engaging means 13, the plate-making by the plate-making means 3 and the winding around the plate cylinder 9 are simultaneously performed.

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 performing printing by winding a master having a plate made on an outer peripheral surface of a printing drum, and more particularly to a plate making and plate feeding mechanism.

[0002]

2. Description of the Related Art A rotatable printing drum constructed by winding a plurality of layers of a resin or metal mesh mesh screen around a porous support cylinder, and a paper made of synthetic paper or a synthetic fiber or a Japanese paper fiber wound on a thermoplastic resin film. Using a master with a laminated structure in which a porous support made of a mixture of fibers and a laminate is attached, the surface of the thermoplastic resin film of the master is heated by a thermal head while making a plate, transported by a platen roller, and then wound around a print drum. The printing paper is supplied with an appropriate amount of ink to the inner peripheral surface of the printing drum by ink supply means having an ink pump, an ink sensor, and the like provided inside the printing drum, and the printing paper is pressed by a pressing member such as a press roller or an impression cylinder. Is pressed onto the print drum to transfer the ink oozing from the print drum opening and the master punch to the printing paper. Digital thermal stencil printing apparatus which performs printing are well known.

In this stencil printing machine, a master is conveyed while making a stencil by a thermal head and a platen roller.
The leading end of the master is locked by a clamper provided on the plate cylinder, and thereafter, the master is made by a thermal head while rotating the plate cylinder and transporting the master by a platen roller. In this case, the plate making start position on the master and the locking position of the clamper are both determined based on the number of steps of the stepping motor provided on the platen roller.

[0004]

In the above-described configuration, plate making is performed based on the number of steps from the leading end position of the master that has been initially set or cut by the cutting means. However, even when locked by the clamper, the locked state of the master has no reproducibility due to the state of the curl at the tip of the master, and the plate making start position with respect to the phase of the plate cylinder cannot be specified.

Japanese Patent Application Laid-Open No. Hei 6-270377 discloses a technique for starting plate making after locking the leading end of a master with a clamper. However, the locking state of the master by the clamper has no reproducibility. For this reason, if wrinkles occur in the master during locking, there is a problem that the plate making start position is shifted with respect to the phase of the plate cylinder.

The deviation of the plate making start position with respect to the phase of the plate cylinder becomes a deviation of the image position during normal printing and can be adjusted by test printing. However, multicolor printing in which a plurality of plate cylinders are passed at one time is performed. Or for full color printing,
A color shift occurs between the colors, which is a major problem.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a stencil printing machine which can solve the above-mentioned problems and can specify a master making start position for a master with respect to a printing drum cylinder phase.

[0008]

According to the first aspect of the present invention,
A porous cylindrical rotatable plate cylinder having a master locking means on an outer peripheral surface, a master storage means for storing a roll-wound master, and the master storage means disposed on a conveyance path of the master, Plate making means for making and transporting the master drawn out from the master storage means, and cutting means for cutting the master, which is disposed on the transport path downstream of the plate making means in the master transport direction, and A stencil printing machine for simultaneously performing plate making on the master by the plate making means and winding the master around the plate cylinder after the master is locked by master locking means, wherein the phase of the plate cylinder is Detecting means, a control means for operating the plate making means based on a detection signal from the phase detecting means, and rotating the plate cylinder with a predetermined torque when the master is wound around the plate cylinder. Constant torque And having a rotating means.

According to a second aspect of the present invention, in the stencil printing apparatus according to the first aspect, the constant torque rotating means further includes a DC motor and a current detecting means.

According to a third aspect of the present invention, in the stencil printing apparatus of the first aspect, the constant torque rotating means further includes a torque limiter.

[0011]

FIG. 1 is a front view of a main part of a stencil printing apparatus employing an embodiment of the present invention. In FIG.
A master roll 1a in which a master 1 formed by attaching a thin Japanese paper of about 40 μm to a thin thermoplastic resin (polyethylene terephthalate) film of 2 μm and wound in a roll shape is formed.
The core 1b is rotatably and detachably supported by master storage means 2 provided in a casing (not shown) of the stencil printing apparatus.

A plate making means 3 is provided on the left side of the master roll 1a. The plate making means 3 comprises a thermal head 4 for making a hot melt perforated plate making of the thermoplastic resin film of the master 1.
And a platen roller 5 for transporting the master 1. The thermal head 4 is urged toward the platen roller 5 by urging means (not shown), and the platen roller 5 is driven to rotate by a stepping motor 6. The operations of the thermal head 4 and the stepping motor 6 are controlled by control means 21 described later.

A cutting means 7 is provided on the left side of the plate making means 3. The cutting means 7 includes an upper blade 7a as a moving blade and a lower blade 7b as a fixed blade. The upper blade 7a rotates on the lower blade 7b in the master width direction (the direction of the paper in the drawing). Master 1 is disconnected. A master transport roller pair 8 is provided on the left side of the cutting means 7. In the master transport roller pair 8 including the driving roller 8a and the driven roller 8b, the driving roller 8a is rotationally driven by a driving unit (not shown), and the driven roller 8b pressed against the driving roller 8a by the urging unit (not shown) is connected to the driving roller 8a. And go around. The driving roller 8a is provided with an electromagnetic clutch (not shown). When the electromagnetic clutch is turned on, the driving force from a driving unit (not shown) is cut off, and the master roller 1a is held between the driving roller 8a and the driven roller 8b. When the master 1 is pulled out with a predetermined force, the master 1 rotates.

On the left side of the master transport roller pair 8, a plate cylinder 9 is provided.
Are arranged. A plate cylinder 9 having ink supply means (not shown) inside and having flanges at both ends rotatably supported by a support shaft 9a also serving as an ink supply pipe has a drive gear 9b and a shielding plate 10 on the outer surface of one of the flanges. And The drive gear 9b meshes with a transmission gear 11 rotatably supported by a housing side plate (not shown), and the shield plate 10 passes between detection units of a sensor 12 which is a photo interrupter fixed to the housing side plate (not shown). It is provided as possible. On the outer peripheral surface of the plate cylinder 9, a clamper 13 as a master locking means for locking the leading end of the master 1 is arranged. The clamper 13 is opened and closed by opening and closing means (not shown).

In the above configuration, the phase detecting means 14 is constituted by the shielding plate 10 and the sensor 12. When the clamper 13 is located right above as shown in FIG.
Is set to be located. The detection signal from the phase detection unit 14 is sent to the control unit 21 described below.

Below the plate cylinder 9, a first motor 15 for low-speed rotation and a second motor 16 for high-speed rotation are arranged. The first motor 15 composed of a DC motor is provided with a current detector 18 as current detecting means for measuring a current flowing in the motor, and the output shaft of each of the first motor 15 and the second motor 16 has a tooth. The attached pulleys 15a and 16a are attached. A toothed pulley 11a is mounted concentrically with the transmission gear 11, and a toothed belt 17 is stretched between the toothed pulleys 11a, 15a, and 16a. Thus, the rotation driving force of the first motor 15 and the second motor 16 is transmitted to the driving gear 9b via the transmission gear 11, and the plate cylinder 9 is rotated. Each toothed pulley 15
Electromagnetic clutches (not shown) are provided for the motors a and 16a, respectively, so that when one of the first motor 15 and the second motor 16 is operating, the other stops, and no load is applied to the other output shaft. Is configured. In the above-described configuration, the first motor 15 and the current detector 18 constitute a constant torque rotation unit 19. The operations of the second motor 16 and the constant torque rotation unit 19 are controlled by a control unit 21 described later.

In the vicinity of the lower portion of the plate cylinder 9, there is provided a press roller 20 as pressing means for pressing the printing paper fed from a paper feeding means (not shown) against the outer peripheral surface of the plate cylinder 9. The press roller 20 is rotatably supported at both ends by a pair of arm members (not shown), and the arm member (not shown) is swingably supported by swing means (not shown). The press roller 20 is selectively positioned at a solid line position in which the outer peripheral surface is separated from the outer peripheral surface of the plate cylinder 9 and a two-dot chain line position in which the outer peripheral surface is pressed against the outer peripheral surface of the plate cylinder 9. You.

FIG. 2 is a block diagram of the control means 21 used in one embodiment of the present invention. As shown in the figure, a control means 21 composed of a known microcomputer having a CPU, a ROM, a RAM and the like is provided with a step number signal from a stepping motor 6 constituting the plate making means 3 and a sensor 12 constituting a phase detecting means 14. , The platen roller 5 (stepping motor) based on a plate cylinder position signal from the printer, a first motor current signal from a current detector 18 constituting the constant torque rotating means 19, and an operation command from an operation panel (not shown). 6),
The operation of the first motor 15 and the second motor 16 is controlled.

The operation of the stencil printing apparatus used in the present embodiment based on the above configuration will be described below. In the initial state, the leading end of the master 1 has been cut by the cutting means 7 during the previous plate-making process, and has been conveyed by the platen roller 5 to a position about 10 mm downstream from the clamping position of the master conveying roller pair 8. . When the operator presses a plate making start key on an operation panel (not shown), a plate discharging means (not shown) is activated, and the plate cylinder 9 is rotated clockwise in FIG. Is peeled off.

When the plate discharging operation is completed, an operation command is sent from the control means 21 to the first motor 15, and the plate cylinder 9 is rotated at a low speed in the counterclockwise direction in the figure. And the plate cylinder 9
When the rotation position of the sensor reaches a predetermined position, and the shielding plate 10 enters between the detection parts of the sensor 12 and interrupts the optical path of the sensor 12, a signal is sent from the sensor 12 to the control means 21 and the operation of the first motor 15 is started. The plate cylinder 9 is stopped, and stops at a predetermined position. At this time, the rotation of the plate cylinder 9 is performed at a very low speed, and the variation of the stop position due to the inertial force and the load fluctuation is suppressed to a small value.
2, another sensor is provided on the upstream side in the plate cylinder rotation direction relative to 2, and when the shield plate 10 crosses the other sensor, the rotational peripheral speed of the plate cylinder 9 is slowed down, or the first motor 15 is provided with a rotary encoder, By controlling the stop by counting the pulses, the variation in the stop position of the plate cylinder 9 may be further reduced. The stop position accuracy here may be converged to about ± 1 mm. When the plate cylinder 9 stops at a predetermined position, an opening / closing means (not shown) operates to open the clamper 13.

When the clamper 13 is released, an operation signal is sent from the control means 21 to the plate making means 3, and the stepping motor 6 starts operating. Stepping motor 6
The platen roller 5 rotates in the counterclockwise direction in the figure by the operation of, and the leading end of the master 1 is conveyed toward the clamper 13. From the number of steps of the stepping motor 6,
When the control means 21 determines that the leading end of the master 1 has reached a predetermined position on the clamper 13, the control means 21 sends a command to the stepping motor 6 to stop the operation of the stepping motor 6. In this embodiment, the position of the tip of the master 1 with respect to the clamper 13 is specified by the number of steps of the stepping motor 6. However, a sensor for detecting the tip of the master 1 is provided on the transport path of the master 1, and Master 1 based on output signal
It may be configured to specify the position of the leading end.

When the stepping motor 6 stops, the opening means (not shown) is operated to close the clamper 13 and the leading end of the master 1 is locked on the plate cylinder 9 as shown in FIG. Thereafter, the control means 21 sends the constant torque rotation means 1
9, the first motor 15 is operated, the electromagnetic clutch provided on the drive roller 8a is turned on, and the plate cylinder 9 is driven to rotate by a small amount in the counterclockwise direction in FIG. The generated torque of the first motor 15 is
The predetermined torque is set to be sufficiently small with respect to the tensile strength of the master 1. The tension applied to the master 1 by the predetermined torque is such that the master 1 does not elongate and the master 1 Is set to a value that does not cause detachment from the clamper 13 or the holding portion of the plate making means 3, and is set to a minimum tension at which the deflection generated in the master having no waist disappears. When the first motor 15 rotates at a constant torque, the rotation of the platen roller 5 is stopped, so that a tension is applied to the master 1 by a predetermined torque, and as shown in FIG. The deflection of the master 1 between the two is absorbed.

The predetermined torque by the constant torque rotating means 19 is maintained at a constant value by detecting the current flowing in the first motor 15 which is a DC motor by the current detector 18. When the detected current value is larger than the current value (threshold value) corresponding to the predetermined torque,
By lowering the voltage applied to the motor 15 and increasing the voltage applied to the first motor 15 when the voltage is small, the motor current value is kept constant and a predetermined torque is maintained.

When the control means 21 determines that the deflection of the master 1 has been extended by the output from the current detector 18,
An operation command is sent to the stepping motor 6, and the platen roller 5 is driven to rotate counterclockwise in FIG.
The rotation peripheral speed of the platen roller 5 is controlled by the first motor 15
The rotation peripheral speed of the plate cylinder 9 is set to be lower than
In addition, since the rotation of the plate cylinder 9 by the constant torque rotating means 19 is continued, the plate cylinder 9 starts to rotate counterclockwise in FIG. 1 at a low speed.

When the shield plate 10 moves due to the rotation of the plate cylinder 9 and separates from the detecting portion of the sensor 12 as shown in FIG. 5, a signal is outputted from the sensor 12 to the control means 21. Upon receiving the signal, the control means 21 outputs an operation command to the thermal head 4 to cause the heating elements of the thermal head 4 to generate heat and start a plate making operation on the master 1. Since the position at which the shielding plate 10 is separated from between the detection units of the sensor 12 and the position of the heating element of the thermal head 4 are in an absolute positional relationship determined by the layout, the plate making start position on the master 1 with respect to the phase of the plate cylinder 9 is obtained. Is specified. The timing for operating the thermal head 4 may be after a predetermined number of pulses or a time delay is provided.

Therefore, even if the cutting position of the master 1 by the cutting means 7 or the locking position by the clamper 13 varies, the plate making start position on the master 1 is locked on the plate cylinder 9 and the deflection is prevented. Since the position of the extended master 1 is specified on the basis of the extended position, the variation in the image position on the plate cylinder 9 is greatly reduced as compared with the conventional one. Thereby, even when multi-color printing or full-color printing is performed, color misregistration between each color is suppressed, and a good printed matter can be obtained. Also, during the plate making operation, the constant torque rotation of the plate cylinder 9 by the constant torque rotating means 19 is performed, so that the master 1 is always given an appropriate tension,
The master 1 is beautifully wound on the outer peripheral surface of the plate cylinder 9 while preventing wrinkles from occurring.

The master making operation by the thermal head 4 is completed, and the master 1 is determined by the number of steps of the stepping motor 6.
When the control means 21 determines that the transfer of one plate has been completed, the operation of the stepping motor 6 is stopped, and then the cutting means 7 is operated to cut the master 1. Master 1
After the cutting, the control means 21 drives the first motor 15 to rotate at an appropriate peripheral speed faster than that at the time of plate making. Thus, the plate cylinder 9 is driven to rotate counterclockwise in FIG. 1, and the rear end of the cut master 1 is wound around the plate cylinder 9. At this time,
When an electromagnetic clutch (not shown) provided on the drive roller 8a is turned on and an appropriate tension is applied to the master 1 pulled out from the master transport roller pair 8, wrinkling of the master 1 is prevented.

After the operation of winding the master 1 around the plate cylinder 9 is completed, the control means 21 sends an operation command to the stepping motor 6 to rotate the platen roller 5. This allows
The cut end of the master 1 is transported to the same position as the initial state. Thereafter, when the operator presses a print start key on an operation panel (not shown), an operation command is sent from the control means 21 to the second motor 16 and the plate cylinder 9
Is rotated at a high speed, and printing paper is continuously fed from a paper feeding unit (not shown). The fed sheet is pressed onto the outer peripheral surface of the plate cylinder 9 by a press roller 20 which is rocked by a rocking means (not shown) to transfer a print image, and then discharged out of the apparatus by a paper transport means (not shown). You. When the set number of prints is exhausted, the second motor 16 stops, and the stencil printing machine enters a standby state.

In the above embodiment, the DC motor and the current detector are used as the constant torque rotating means. However, as the constant torque rotating means, a motor and a torque limiter comprising a friction disk or the like are used. The configuration may be such that the motor idles when it becomes high. Further, in the above embodiment, the plate cylinder is rotationally driven by different motors during the plate making operation and the printing operation. However, the plate cylinder is rotationally driven by controlling one motor at a high level. Is also good. In the above embodiment, the plate cylinder 9 is rotatable clockwise and counterclockwise, and the toothed pulleys 15a and 16a are provided with an electromagnetic clutch (not shown). In this case, a one-way clutch may be used instead of the electromagnetic clutch as the clutch provided on each toothed pulley 15a, 16a.

[0030]

According to the present invention, the plate making start position on the master with respect to the plate cylinder phase is specified, so that even if multicolor printing or full-color printing is performed, color misregistration between the colors is suppressed. And a good printed matter can be obtained.

[Brief description of the drawings]

FIG. 1 is a front view of a main part of a stencil printing apparatus employing an embodiment of the present invention.

FIG. 2 is a block diagram of control means used in one embodiment of the present invention.

FIG. 3 is a diagram illustrating a locked state of a master according to an embodiment of the present invention.

FIG. 4 is a diagram illustrating a master winding operation according to an embodiment of the present invention.

FIG. 5 is a diagram illustrating a plate making start position in one embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 master 2 master storage means 3 plate making means 7 cutting means 9 plate cylinder 13 master locking means (clamper) 14 phase detecting means 15 DC motor (first motor) 18 current detecting means (current detector) 19 constant torque rotating means 21 Control means

Claims (3)

[Claims] A porous cylindrical rotatable plate cylinder having a master locking means on an outer peripheral surface; a master storage means for storing a roll-wound master; and a master storage means disposed on a transport path of the master. Provided, plate making means for making and transferring the master drawn out from the master storage means, and cutting means for cutting the master, which is disposed downstream of the plate making means on the transfer path in the master transfer direction. A stencil printing apparatus, comprising: after the master is locked by the master locking means, simultaneously performing plate making on the master by the plate making means and winding the master around the plate cylinder, Phase detection means for detecting the phase of the plate cylinder; control means for activating the plate making means based on a detection signal from the phase detection means; and With the torque of A stencil printing machine comprising: a constant torque rotating means for rotating the stencil printing machine. 2. The stencil printing apparatus according to claim 1, wherein said constant torque rotating means has a DC motor and a current detecting means. 3. The stencil printing apparatus according to claim 1, wherein said constant torque rotating means has a torque limiter.