JP2003136823A - Stencil printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of an image deflection in a stencil printer in which a printing sheet is separated from a plate cylinder by a separating pawl for injecting air in cooperation with the rotation of the cylinder. SOLUTION: The stencil printer comprises the plate cylinder 1 in which a stencil base sheet is wound and which is rotated, an ink supply means 7 in the cylinder, a pressing roller 11 under the cylinder, the separating pawl 20 for injecting the air from its distal end, an air supply means 25 for supplying the air to the pawl, and a control means 40. The air supply means 25 compresses the air in cooperation with the rotation of the cylinder, and can regulate a discharging pressure under the control of the control means. The control means controls the regulating means of the air supply means with preset table data as a reference in response to the rotating speed of the cylinder, the printing width, margin and printability of the distal end of the printing sheet as factors for affecting the adhering state of the sheet to the cylinder, and sets an injecting pressure from the pawl. Both the soaring of the sheet and the image deflection of the sheet can be suppressed irrespective of the rotating speed of the cylinder and the mage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION A stencil printing machine according to the present invention comprises a stencil sheet having an outer peripheral surface wound with a stencil sheet and an inner peripheral surface supplied with ink to rotate, and a pressing body disposed in the vicinity of the cylinder. The printing paper is sandwiched between the plate cylinder and the pressing body for printing, and the printing paper is separated from the plate cylinder by a separating claw that ejects air from the front end. And the present invention is
In such a stencil printing machine, regardless of the printing conditions such as the rotation speed of the plate cylinder, the printing rate and the printing width of the printing paper, the printed image of the printing paper separated from the printing cylinder does not have image defects (image blurring). It is the one.

[0002]

2. Description of the Related Art A typical stencil printing machine shown in FIG. 3 has a plate cylinder 100 which rotates about its own axis. An ink supply device is provided inside the ink-permeable plate cylinder 100 to supply ink to the inner surface. A clamp device 101 is provided on the outer surface of the plate cylinder 100 to hold the leading end of the stencil sheet 102 that has been made, and the stencil sheet 102 is wound around the outer peripheral surface of the plate cylinder 100. Below the plate cylinder 100, the pressure roll 10
3 is provided so as to be able to move up and down. In the vicinity of the plate cylinder 100, a separation claw 104 that swings in association with the rotation of the plate cylinder 100 by a mechanism such as a cam is provided. Air is ejected from the tip of the separation claw 104. This air is supplied by the reciprocating motion of the piston of the pump driven in association with the rotation of the plate cylinder 100.

The printing paper supplied at the time of printing is pressed against the plate cylinder 100 by the raised pressing roll 103, is sandwiched between the rotating plate cylinder 100 and the pressing roll 103, and is conveyed and printed. The printing paper that has been printed and adhered to the plate cylinder 100 with the printing ink is separated from the plate cylinder 100 by the separation claw 104 that ejects air from the leading edge, and is carried out by the transport mechanism 105 below the plate cylinder 100 that has a suction function. To be done.

[0004]

In the conventional stencil printing apparatus as described above, an image defect (image blur) occurs when a printed image (particularly a solid portion) is present at the leading end of the printing paper. was there. In order to solve this problem, the inventors of the present application investigated the cause of the image defect.

The inventor of the present application considered the print image, the print position, the air amount (air pressure) from the separation claw, etc. as factors that cause the image defect. What is known to the inventor of the present application as to what kind of state the printing paper is actually separated from the plate cylinder and how it is moving when an image defect occurs will be described below.

The separation claw 104 swings in synchronization with the rotation of the plate cylinder 100, avoids interference with the clamp device 101 of the plate cylinder 100, and then separates the printing paper from the plate cylinder 100. Approach. When the image defect occurs,
The present inventor has confirmed that the phenomenon described below occurs when the printing paper is separated from the plate cylinder 100 and passes near the separation claw 104.

In the normal case, as shown in FIG. 4, the printing paper 200 is guided from the plate cylinder 100 to the tip of the separation claw 104, and the tip thereof is directed toward the conveying mechanism 105 having a suction function located below. Is separated into

When an image defect occurs, as shown in FIG. 5, the leading edge of the printing paper 200 is below the transport mechanism 105.
Direction toward the bottom of the separation claw 104 above the printing paper 200 (the rising of the printing paper).

Further, the plate cylinder 100 rotates to rotate the printing paper 200.
When the paper is sent out, the leading edge of the printing paper 200 collides with the bottom of the separation claw 104 as shown in FIG. 6, and the printing paper 200 is blocked by the bottom of the separation claw 104 in the traveling direction as shown in FIG. Becomes loose and bends downward (convex downwards). At this time, as indicated by the arrow in FIG. 9, a force is drawn to the print sheet 200 toward the position where the separation claw 104 is located (in the illustrated example, the approximate center in the width direction of the print sheet 200), and the print image is printed. An image blur occurs due to being dragged on the stencil sheet 102 of the plate cylinder 100. After that, when the printing paper 200 is further pushed out from the plate cylinder 100, as shown in FIG. 8, the leading edge of the printing paper 200 is momentarily struck on the transport mechanism 105 as shown in FIG.

Such a phenomenon is remarkable when the pressure of the air jetted from the separation claw 104 is high even when the front end of the printing paper 200 does not collide with the bottom of the separation claw 104. In the mechanism in which the ejection timing of the air for separation and the rotation of the plate cylinder 100 are synchronized, the air ejection pressure is small when the printing speed (plate cylinder rotation speed) is low, and the printing speed (plate cylinder rotation speed) is high. In the case of, the air ejection pressure becomes large. In order to prevent the rising of the printing paper regardless of the printing speed, it is necessary to set the ejection pressure so that the printing paper can be normally separated at the low speed. Therefore, the air injection pressure becomes excessive at high speed. If the jet pressure is excessive, the image defect is likely to occur. However, even when the air pressure for separation is high, the margin of the leading edge of the printing paper is large, the image printing rate at the leading edge of the printing paper is small, or the width of the printing portion at the leading edge of the printing paper is wide. The inventor of the present application considered that the occurrence of image defects may be suppressed.

That is, depending on the types of parameters that affect the printing state, such as the rotation speed of the plate cylinder, the print width at the leading edge of the printing paper, the margin at the leading edge of the printing paper, the printing rate at the leading edge of the printing paper, etc. The inventor of the present application has considered that there is a possibility that it is possible to suppress the rise of the printing paper while suppressing the occurrence of image defects by adjusting the air injection pressure of the separation claw according to the above. It was

An object of the present invention is to prevent image blurring in a stencil printing machine which separates a printing sheet from a plate cylinder by a separation claw which sprays air in association with the rotation of the plate cylinder. From the idea to solve the problem,
We propose the following means for solving problems.

[0013]

A stencil printing apparatus according to a first aspect of the present invention has an ink-permeable peripheral wall around which a stencil sheet that has been plate-made is wound around an outer peripheral surface, and the stencil sheet is provided around the central axis of the stencil sheet. Between the rotating plate cylinder, an ink supply unit provided inside the plate cylinder to supply ink to the inner peripheral surface of the peripheral wall, and rotatably provided outside the plate cylinder, between the plate cylinder. A pressing body that prints on the printing paper by sandwiching the printing paper, a separation claw that has an air ejection port at its tip to separate the printing paper from the plate cylinder, and a rotation of the plate cylinder. In addition to supplying compressed air to the separation claws to eject the compressed air from the ejection port, air supply means having an adjustment means for adjusting the pressure of the air ejected from the separation claws, and at least the plate cylinder Rotation speed, print width of the leading edge of printing paper, for printing Of the ejection port of the separation claw by controlling the adjusting means of the air supply means according to one or more parameters selected from a parameter group that affects the image state including the margin of the tip of the sheet and the printing rate of the tip of the printing paper. It has a control means which adjusts the pressure of the air injected from.

A stencil printing apparatus according to a second aspect of the present invention is the stencil printing apparatus according to the first aspect, further comprising reading means for reading an image of an original, and the control means uses the data read by the reading means for the original. It is characterized in that the above parameters are determined.

A stencil printing apparatus according to a third aspect of the present invention is the stencil printing apparatus according to the first aspect, wherein the rotational speed of the plate cylinder, the print width of the leading edge of the printing paper, the margin of the leading edge of the printing paper,
The four parameters of the printing rate of the leading edge of the printing paper are divided into a plurality of stages, and the pressure of the air ejected from the ejection port of the separation claw is determined for each of a plurality of states set by the combination of the respective stages of the parameters. The control means has table data.

A stencil printing machine according to a fourth aspect is the stencil printing machine according to the first aspect, wherein the air supply means is a pump provided with a piston that is interlocked with the rotation of the plate cylinder, and the adjusting means. Is either a device for adjusting the stroke of the piston or at least one of a control valve for air supplied from the pump.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION One example of an embodiment of the present invention is shown in FIG.
2 and FIG. 2. The structure of the main part of the stencil printing apparatus of this example will be described. Plate cylinder 1 is a stencil sheet 2
Has an ink-permeable peripheral wall 3 wound around the outer peripheral surface. The plate cylinder 1 rotates around its own central axis 4 by a driving means 5 such as a motor. The outer peripheral surface of the peripheral wall 3 is provided with a clamp means 6 for holding the front end of the stencil sheet 2. The stencil sheet 2 is wound around the outer peripheral surface of the peripheral wall 3 with its front end held by the clamp means 6.

Inside the plate cylinder 1, ink supply means 7 for supplying ink to the inner peripheral surface of the peripheral wall 3 is provided. The ink supply unit 7 is in contact with the inner peripheral surface of the peripheral wall 3 and rotates with the squeegee roller 8 and a squeegee roller 8 at a predetermined interval.
It has a doctor roller 9 provided in the vicinity of, and an ink supply pipe 10 for supplying ink between the squeegee roller 8 and the doctor roller 9.

A pressing roller 11 as a pressing body is provided outside the plate cylinder 1 in proximity to the plate cylinder 1. The pressing roller 11 can move up and down. The pressure roller 11 rotates in the opposite direction to the plate cylinder 1. The printing paper supplied by the supply roller 12 is sandwiched between the raised pressing roller 11 and the plate cylinder 1, and is conveyed as the plate cylinder 1 rotates. The ink inside the plate cylinder 1 is pushed by the squeegee roller 8 and passes through the peripheral wall 3 and the perforated portion of the stencil sheet 2, and is transferred to the printing paper to form an image.

Next to the plate cylinder 1, there is provided a separating claw 20 which is a peeling means for peeling the printing paper stuck to the stencil sheet 2 of the plate cylinder 1. The separation claw 20 is arranged on the opposite side of the plate cylinder 1 from the supply roller 12.
The separation claw 20 is provided in the approximate center of an operation shaft 23 provided in the vicinity of the plate cylinder 1 in parallel with the central axis 4 of the plate cylinder 1.
The operation shaft 23 is interlockingly connected to the central axis 4 of the plate cylinder 1 by a transmission mechanism such as a cam (not shown) as shown by an arrow line connecting to the central axis 4 in FIG. Therefore, the separation claw 20 is synchronized with and interlocked with the rotation of the plate cylinder 1 by the driving means 5.
Can be swung at a predetermined timing, and the stencil sheet peeling operation can be appropriately performed while the clamping means 6 is performing the avoiding operation.

The separation claw 20 is provided with an air supply means 25, and the spray port provided at the tip of the separation claw 20 can spray the air for peeling the printing paper. The air supply means 25 of this example is one in which a piston reciprocates in a cylinder to eject air of a predetermined pressure, and its driving force is as shown by an arrow line connected to the central axis 4 in FIG. It's got from one revolution. Therefore, when the rotation speed of the plate cylinder 1 is low, the pressure of the air injected from the separation claw 20 is low, and conversely, when the rotation speed of the plate cylinder 1 is high, the pressure of the air injected from the separation claw 20 is also low. Get higher The air jetted from the separation claw 20 is blown onto the surface of the front end of the printing paper stuck to the stencil sheet 2 of the plate cylinder 1 facing the stencil sheet. When the swingable separating claw 20 is in a position close to the plate cylinder 1, the air jet direction thereof substantially coincides with the tangential direction of the plate cylinder 1.

The air supply means 25 of this embodiment is a piston type pump as described above, and is provided with an adjusting means capable of arbitrarily controlling the jet pressure of air by freely adjusting the piston stroke. However, the air supply means that can be adopted in the present invention is not limited to such a configuration. That is, regardless of the mechanism as the air supply means (and therefore the mechanism as the pump), the rotation of the plate cylinder 1 is interlocked.
It is a device that compresses or supplies air in synchronism, and may have means for adjusting the discharge pressure or the discharge air amount. For example, a pump may be provided with a valve that is a pressure adjusting means on its discharge side.

Below the separating claw 20, a belt type conveying mechanism 15 having a suction function is provided. The printing paper peeled off from the plate cylinder 1 is sucked by the carrying mechanism 15 and carried to a paper delivery tray (not shown).

The stencil printing apparatus of this embodiment has a document reading section 3
Has 0. The reading unit 30 can read an image of a document placed here and output it as image data. Although not shown, the stencil printing machine of this example has a plate making section. The plate making section can punch an image on the stencil sheet based on the image data obtained by the reading section 30. The stencil sheet prepared here is mounted on the plate cylinder 1 as described above.

The stencil printing machine of this example has a control means 40. The control means 40 is basically for integrally controlling the basic operations of the entire apparatus, such as reading of originals, plate making, and printing, as shown in FIG.
Some of the control operations that are particularly relevant to the features of this example are indicated by arrows. That is, the control unit 40 can obtain the data of the original image from the reading unit 30, and can control the driving unit 5 of the plate cylinder 1 and the adjusting unit of the discharge air pressure of the air supply unit 25. Then, the control unit 40 of the present example, according to the rotation speed of the plate cylinder, the print width of the leading end of the printing paper, the margin of the leading end of the printing paper, and the printing rate of the leading end of the printing paper, which are parameters that affect the printed image, The adjusting means of the air supply means 25 is controlled to control the pressure of the air jetted from the jet port of the separation claw 20.

Specifically, the control means 40 determines the four parameters of the document from the data read by the reading section 30, and the separating claw 20 ejects the ink according to the four parameters causing the image defect. Adjust the optimum air pressure of the air to be used.

In order to control the adjustment of the air pressure in accordance with the state of the parameters, the control means 40 previously stores table data as shown in FIG. As shown in FIG. 2, this table data has four parameters, large and small, for each of four parameters, that is, the rotation speed of the plate cylinder, the printing width at the leading edge of the printing paper, the margin at the leading edge of the printing paper, and the printing rate at the leading edge of the printing paper. The pressure of the air jetted from the jet port of the separation claw 20 is divided into five stages, from 1 being weak to 5 being strong, for each of the states of 16 in total set by the combination of each stage of each parameter. There is a crab.

In this example, the ejection pressure level 5 is set as the ejection pressure at which the image defect and the sheet rising are not generated, and the ejection pressures of other lower levels are set on the basis of the ejection pressure.

Next, the operation of the above configuration will be described. According to this example, the document is read by the reading unit 30 and the image data of the document is sent to the control unit 40 before the plate making / printing. Then, the control means 40 respectively determines the level of each of the four parameters indicating the state when printing this original document, and compares the result with the table data shown in FIG. Determines the strength of the injected air pressure.

At the time of printing, the separating claw 20 approaches the plate cylinder 1 after the clamp means 6 is passed, and the tip of the separating claw 20 is inserted between the plate cylinder 1 and the front end of the printing paper not attached to the plate cylinder 1. To do. The separation claw 20 blows the tip of the printing paper downward so that the printing paper is guided downward.

The pressure of the air jetted from the separating claw 20 is
The rotation speed of the plate cylinder 1 at that time, the print width of the leading edge of the printing paper,
Since the optimum value is set according to the margin / printing ratio, the leading edge of the printing paper is directed toward the lower transport mechanism 15,
It does not collide with the bottom of the separation claw 20. Therefore, since the separation claw 20 can peel off the printing paper attached to the stencil sheet with ink without dragging on the stencil sheet, image defects such as image blurring do not occur in the printed image.

In this example, four items are listed as parameters indicating a state where an image defect occurs when a document is printed, and the combination of these parameters controls the air injection pressure from the separating claw 20 stepwise. , 4 as parameters
It is also possible to arbitrarily select and use one or more of the two. Further, although the degree of each parameter is divided into large and small levels, it may be divided into three or more levels. Further, the parameters are not limited to the above four parameters, but other parameters can be adopted as the parameters as long as they can influence the sticking state of the leading edge of the printing paper to the plate cylinder 1. For example, the paper width can be used instead of the print width in the parameters. In that case, the paper width can be replaced by the size of the printing paper.
It is possible to obtain the data of the paper size from the data from the reading unit 30, the data from the paper feeding unit or the data of the printing condition set in the control unit 40, and use the data for the control.

[0033]

According to the present invention, in the stencil printing apparatus for separating the printing paper from the plate cylinder by the separating claws which inject air in association with the rotation of the plate cylinder, the front end of the printing paper is attached to the plate cylinder. Since the adjusting means of the air supply means is controlled according to the parameter that influences the state to adjust the pressure of the air jetted from the separating claw, printing is performed regardless of the rotation speed of the plate cylinder or the printing rate of the image. Both the rising of the paper and the blurring of the image can be suppressed.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an example of an embodiment of the present invention.

FIG. 2 is a diagram showing contents of control table data included in a control unit in an example of an embodiment of the present invention.

FIG. 3 is a diagram showing a stripping operation of printing paper in a conventional stencil printing apparatus.

FIG. 4 is a diagram showing a stripping operation of printing paper in a conventional stencil printing machine.

FIG. 5 is a diagram showing a stripping operation of printing paper in a conventional stencil printing machine.

FIG. 6 is a diagram showing a stripping operation of printing paper in a conventional stencil printing machine.

FIG. 7 is a diagram showing a stripping operation of printing paper in a conventional stencil printing machine.

FIG. 8 is a diagram showing a stripping operation of printing paper in a conventional stencil printing machine.

FIG. 9 is a diagram showing a stripping operation of a printing sheet and its problems in a conventional stencil printing apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Plate cylinder, 2 ... Stencil sheet, 5 ... Motor as a drive means of a plate cylinder, 7 ... Ink supply means, 20 ... Separation nail, 15 ... Conveying mechanism, 25 ... Air supply means, 30 ... Reading part, 40
… Control means.

Claims (4)

[Claims] 1. A plate cylinder that has an ink-permeable peripheral wall wound around the outer peripheral surface of a stencil sheet, and that rotates around its own central axis; and a plate cylinder that is provided inside the plate cylinder. Ink supply means for supplying ink to the inner peripheral surface of the peripheral wall and rotatably provided outside the plate cylinder, and prints on the printing paper by nipping and conveying the printing paper between the plate cylinder A pressing body, a separation claw having an air ejection port at its tip end for separating the printing paper from the plate cylinder, and the above-mentioned means for ejecting compressed air from the ejection port in association with the rotation of the plate cylinder. An air supply means having an adjusting means for supplying pressure to the separation claw and adjusting the pressure of the air jetted from the separation claw, and at least the rotation speed of the plate cylinder, the printing width of the leading edge of the printing paper, and the leading edge of the printing paper. An image that includes the margins and the print ratio of the leading edge of printing paper Stencil having control means for controlling the adjusting means of the air supply means to adjust the pressure of the air jetted from the jet port of the separation claw according to one or more parameters selected from the parameter group affecting the state Printing device. 2. The stencil printing apparatus according to claim 1, further comprising a reading unit for reading an image of a document, wherein the control unit determines the parameter of the document from data read by the reading unit. 3. The four parameters of the rotation speed of the plate cylinder, the print width of the front end of the printing paper, the margin of the front end of the printing paper, and the printing rate of the front end of the printing paper are divided into a plurality of steps, and each step of each parameter is divided. 2. The stencil printing apparatus according to claim 1, wherein the control unit has table data that defines the pressure of the air ejected from the ejection port of the separation claw for each of a plurality of states set by the combination of. 4. The air supply means is a pump provided with a piston that interlocks with the rotation of the plate cylinder, and the adjusting means controls the stroke of the piston and the air supplied from the pump. The stencil printing apparatus according to claim 1, wherein at least one selected from valves is used.