JP2003025703A - Stencil printing equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide stencil printing equipment, with which curling is prevented from developing even at the printing of a plate-making image having a solid image and consequently a favorable printed matter is obtained. SOLUTION: The stencil printing equipment is equipped with an image reading part 7, a plate-making part 3, a plate cylinder 10, a paper feeding part 4, a pressing means 11 for pressing a printing paper P against the plate cylinder 10, a peeling-off means 89 for peeling the printing paper P with an air knife 94 off the plate cylinder 10, a solid image detecting means 136 for detecting whether a solid image is present or not in a copy image, a printing speed varying means 38 shown in Fig. 2 and a pressing force varying means 36 shown in Fig 3. When the solid image is detected with the solid image detecting means 136 in the copy image, the rotary peripheral speed of the plate cylinder 10 is set by the printing speed varying means 38 to the predetermined value and the amount of the ink transmitted from the plate cylinder 10 to the printing paper P is set by the pressing force varying means 36 to the predetermined value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stencil printing apparatus for printing by wrapping a pre-made master on the outer peripheral surface of a plate cylinder, and more specifically, from the outer peripheral surface of the plate cylinder at the time of printing a plate-making image having a solid image. Related to peeling of printing paper.

[0002]

2. Description of the Related Art A rotatable plate cylinder formed by winding a plurality of layers of mesh screens of resin or metal mesh on a peripheral surface of a porous support plate which is a porous support cylinder, and a thermoplastic resin film (thickness). A thermoplastic resin film of a master using a master having a laminated structure in which Washi fibers or synthetic fibers or a mixture of Washi fibers and synthetic fibers are pasted together. The surface is heated and perforated by a thermal head and then wrapped around the plate cylinder. While the ink is supplied by the ink supply means provided inside the plate cylinder, the printing paper is made on the outer peripheral surface of the plate cylinder by pressing means such as a press roller. Printing is performed by causing the ink to seep out from the plate cylinder opening and the master perforation and transfer it to the printing paper by continuously pressing the finished master. Thermal digital stencil printing apparatus is generally known.

Generally, in the above-mentioned stencil printing machine, the printed printing paper is peeled from the plate-making master on the outer peripheral surface of the plate cylinder by a peeling claw which is a peeling means, and is discharged onto a paper discharge tray. This peeling claw is placed near the plate cylinder with a slight gap between the tip and the master so as not to damage the master, and is forced between the printing paper and the master on the outer surface of the plate cylinder. Intervention with the peeling of the printing paper.

However, when there is a solid image portion in the plate-making image formed on the master, the adhesive force of the ink to the printing paper is extremely increased and the printing paper cannot be peeled by the peeling claw, and the printing is performed. If the paper remains stuck to the master or the printing paper is caught by the peeling claw, the peeling operation cannot be performed reliably, which causes a so-called "roll-up" problem. Therefore, a stencil printing machine equipped with a peeling unit that ejects air from the tip of the peeling claw to promote peeling between the master and the printing paper is practically 4-
Japanese Patent Laid-Open No. 62-142677 and Japanese Patent Laid-Open No. 62-142677 each disclose means for blowing air from the upper part of the discharged paper suction unit to the plate cylinder side by a fan.

[0005]

The stencil printing machine described above is generally constructed so that the printing speed can be changed. A plurality of printing speeds are set for each printing machine, and the operator can set these printing speeds. Any one of them can be set arbitrarily. With this printing speed, the contact time between the plate cylinder and the printing paper is shortened by increasing the speed, and the ink density transferred to the printing paper is reduced.By decreasing the speed, the contact time between the plate cylinder and the printing paper is reduced. The ink density that is extended and transferred to the printing paper increases. Therefore, when the ambient temperature is high, the fluidity of the ink is improved, so the printing speed is increased to suppress the amount of ink transfer to the printing paper, and when the ambient temperature is low, the ink solidifies, The printing speed is reduced to secure the amount of ink transfer to the printing paper. Further, even if the printing speed is set to the highest speed, normal image quality is ensured, and therefore in order to improve work efficiency, it is generally used at high speed during normal use.

In such a stencil printing machine, when a master on which a plate-making image having a solid image is formed is wound around a plate cylinder and printing is performed at a high printing speed, each of the above-mentioned peeling means is used as an example. Even if the technique described in the publication is adopted, "rolling up" may occur. This is because the printing speed is so fast that the plate cylinder rotates before the wind force from the air knife of the peeling means sufficiently acts between the printing paper and the master, and as a result, the printing paper and the master cannot be separated. This is because. To solve this, the printing speed should be reduced so that the wind force from the air knife works sufficiently between the printing paper and the master.
When the printing speed is reduced, the amount of ink transferred from the plate cylinder to the printing paper increases, as described above, so that the stickiness of the ink increases and "roll-up" easily occurs. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to provide a stencil printing apparatus capable of obtaining a good printed matter by preventing the occurrence of winding even when printing a plate-making image having a solid image. .

[0007]

The invention according to claim 1 is
An image reading unit that reads an original image, a plate making unit that makes a master based on the image read by the image reading unit,
A plate cylinder around which the master made by the plate making unit is wound,
A sheet feeding unit for feeding the printing sheet, a pressing unit for pushing the printing sheet fed from the sheet feeding unit against the plate cylinder, and a peeling unit for peeling the printing sheet from the plate cylinder with an air knife. In the stencil printing apparatus having, a solid image detecting means for detecting whether or not there is a solid image in the original image, a printing speed varying means for changing a rotational peripheral speed of the plate cylinder, and the pressing means for the plate cylinder. Pressing force varying means for changing the pressing force of the solid image detecting means, when a solid image is detected in the original image by the solid image detecting means,
The rotation speed of the plate cylinder is set to a predetermined value by the printing speed changing means, and the ink transfer amount from the plate cylinder to the printing paper is set to a predetermined value by the pressing force changing means.

According to a second aspect of the present invention, in the stencil printing apparatus according to the first aspect, when the solid image is detected in the original image by the solid image detecting means, the rotational peripheral speed of the plate cylinder is changed. In order to lower the amount of ink transferred from the plate cylinder to the printing paper at the same time, the control unit controls the printing speed varying unit and the pressing force varying unit.

According to a third aspect of the present invention, in the stencil printing apparatus according to the second aspect, there is further provided a solid image ratio detecting means for detecting a ratio of the solid image in the original image, and the detected ratio. The control means controls the printing speed varying means and the pressing force varying means in accordance with the above.

According to a fourth aspect of the present invention, in the stencil printing apparatus according to the third aspect, the wind force of the peeling unit is variable, and the control unit changes the wind force according to the ratio. To do.

According to a fifth aspect of the present invention, in the stencil printing apparatus according to any one of the first to fourth aspects, it is further determined whether or not any image by the solid image detecting means is a solid image. The determination is made based on the area of the image, and the threshold value for determining whether the image is a solid image changes according to the distance from the front end side of the printing paper.

According to a sixth aspect of the present invention, in the stencil printing apparatus according to the fifth aspect, the threshold value further increases as the distance from the front end side of the printing paper increases.

[0013]

FIG. 1 shows a stencil printer according to an embodiment of the present invention. In the figure, the stencil printer 1 is
The printing unit 2, the plate making unit 3, the paper feeding unit 4, the plate discharging unit 5, the paper discharging unit 6,
It has an image reading unit 7 and is placed on a dedicated table 8.

The printing section 2 arranged at the substantially center of the printing apparatus main body 9 has a plate cylinder 10 and a press roller 11 as a pressing means. As shown in FIGS. 1 and 2, the plate cylinder 10 includes a pair of flanges 13 rotatably supported by a support shaft 12 also serving as an ink supply pipe, and not shown in the drawing which are wound around the outer peripheral surface of each flange 13. It is mainly composed of a porous support plate, and a pair of brackets 14 is attached to the outside of each flange 13. An end portion of the support shaft 12 on the rear side of the device protrudes from the bracket 14, and each bracket 14 is integrally connected by a connecting bracket 15.
A drive gear 16 is integrally provided with the flange 13 between the flange 13 on the rear side of the device and the bracket 14.
The connecting bracket 15 is configured to be engageable with a rail member (not shown) provided in the printer body 9, and the support shaft 1
The rear end of the apparatus 2 is configured to be engageable with a bearing member (not shown) provided in the printing apparatus main body 9. The bracket 14 and the connecting bracket 15 on the front side of the apparatus are provided with a handle (not shown). By gripping the handle and pulling it out in the paper width direction orthogonal to the paper transport direction X shown by an arrow Y in FIG. The plate cylinder 10 is configured to be attachable to and detachable from the printing apparatus body 9 at the home position.

Inside the plate cylinder 10, an ink supply means 17 is arranged as shown in FIGS. The ink supply means 17 includes a support shaft 12, an ink supply pipe 18, an ink roller 19, a doctor roller 20, and the like.

A plurality of small holes are bored in the support shaft 12, and an ink supply pipe 18 having a plurality of ink discharge ports is connected to the holes. The ink roller 19 is rotatably supported between side plates (not shown) provided in the plate cylinder 10, and its peripheral surface is arranged close to the inner peripheral surface of the plate cylinder 10. It is rotationally driven in the same direction as 10. The doctor roller 20 is also rotatably supported between the side plates, the peripheral surface thereof is disposed close to the peripheral surface of the ink roller 19, and is rotationally driven in the opposite direction to the plate cylinder 10 by a driving means (not shown). . Ink supplied from the ink supply pipe 18 is collected in a space having a wedge-shaped cross section formed in the vicinity of the ink roller 19 and the doctor roller 20 to form an ink pool 21.

On the outer peripheral surface of the plate cylinder 10, there is formed a stage section 22 which is a plane along one generatrix of the plate cylinder 10. On the stage section 22, a master is arranged on the outer peripheral surface of the plate cylinder 10. A clamper 23 for holding is provided. The clamper 23 is opened and closed by an opening and closing means (not shown) when the plate cylinder 10 occupies a predetermined position. Plate cylinder 1 described above
0 is rotationally driven by a plate cylinder driving means 24, which will be described later, provided inside the printing apparatus main body 9.

A press roller 11 is arranged below the plate cylinder 10. The press roller 11 is formed by winding an elastic body such as rubber around the outside of a metal core, and is provided so as to extend parallel to the axial direction of the plate cylinder 10. Figure 3
As shown in FIG. 2, shaft portions 11 a are integrally provided at both ends of the core portion of the press roller 11, and the press roller 11 is swingably supported by the swing means 25.

The swinging means 25 has a horizontal shaft 26, arm members 27 and 28, an intermediate connecting stay 29, a transmission arm 30, an operating plate 31, a tension spring 32, a printing cam 33 and the like. The horizontal shaft 26 is provided substantially parallel to each shaft portion 11a, and both ends thereof are rotatably supported between a pair of side plates 34 provided in the printing apparatus main body 9. Each arm member 27, 28 has one end rotatably supporting the shaft 11a, and the other end rotatably supported by the horizontal shaft 26. The hollow prismatic intermediate connecting stay 29 has its both ends fixed to substantially the center of each arm member 27, 28.
8 are integrally connected. A transmission arm 30 having a substantially U-shaped tip portion has its base portion fixed to the horizontal shaft 26, and the tip portion holds the intermediate connecting stay 29 with a slight gap.

The actuating plate 31 having a substantially triangular shape has a first top portion attached to the end of the horizontal shaft 26 projecting from one side plate 34, and a cam follower 35 is rotatable on the second top portion thereof. Is attached to one end of the tension spring 32, the other end of which is attached to a pressing force varying means 36 described later. As a result, the actuating plate 31 is always provided with a biasing force for pressing the press roller 11 against the plate cylinder 10.

Below the operating plate 31, when the plate cylinder 10 and the press roller 11 come into contact with each other, they come into contact with the cam followers 35 and rotate the operating plate 31 about the horizontal shaft 26 in the clockwise direction in FIG. A printing pressure cam 33 having a large diameter portion and a small diameter portion that does not come into contact with the cam follower 35 at the time of contact is arranged. The printing pressure cam 33 is fixed to a cam shaft 37, and the cam shaft 37 is a plate cylinder driving means 2 described later.
It is rotationally driven by 4.

The plate cylinder driving means 24, as shown in FIG.
It has a main motor 38, a speed reduction means 39, a synchronization means 40, etc., and is arranged inside the printing apparatus main body 9.
A main motor 38, which is a variable speed type motor and functions as a printing speed changing means, is attached inside the printing apparatus main body 9 via a bracket (not shown), and its output shaft 38a has a slit formed of a well-known photo rotary encoder. A disc 41 is attached. In the vicinity of the slit disk 41 of the printer main body 9, a sensor 42 composed of a photo interrupter for sandwiching the slit disk 41 at a predetermined interval is arranged. Along with the operation of the main motor 38, the sensor 42 detects the predetermined number of pulses generated when the slit disk 41 rotates, so that the rotational peripheral speed of the main motor 38 is detected. The peripheral speed of the plate cylinder 10, that is, the printing speed is controlled.

The speed reducing means 39 has a drive pulley 43, a timing pulley 44, a timing belt 45, a small diameter gear 46, a large diameter gear 47 and the like. A drive pulley 43, which is a toothed pulley, is attached to the end of the output shaft 38a, and a timing pulley attached to a pulley shaft 48 rotatably supported by a frame (not shown) of the printing apparatus main body 9 in the vicinity thereof. 44 are provided. A timing belt 45 is wound around the drive pulley 43 and the timing pulley 44, and the rotational driving force of the main motor 38 is transmitted to the pulley shaft 48.

A small diameter gear 46 is attached to the pulley shaft 48 integrally with the timing pulley 44, and the small diameter gear 46 is meshed with a large diameter gear 47 attached to the cam shaft 37. As a result, the rotational driving force of the main motor 38 is transmitted to the printing pressure cam 33, and the printing pressure cam 33 is rotationally driven in synchronization with the main motor 38.

A synchronizing means 40 is arranged above the speed reducing means 39. The synchronizing means 40 has a lower pulley 49, an upper pulley 50, a main belt 51, a detachable gear 52 and the like. A lower pulley 49, which is a toothed pulley, is attached to the cam shaft 37 integrally with the large-diameter gear 47, and is rotatably supported by a frame (not shown) of the printer body 9 above the lower pulley 49. Upper pulley 5 consisting of a pulley with teeth attached to the pulley shaft 53
0 is set. Lower pulley 49 and upper pulley 50
Have a toothed outer peripheral portion of the same diameter, and are connected by a main belt 51 composed of a timing belt so that the respective rotation ratios are 1: 1.

The detachable gear 52 is attached to the end of the pulley shaft 53, and is arranged so as to mesh with the drive gear 16 when the plate cylinder 10 is mounted on the printing apparatus main body 9. With this configuration, the rotational driving force of the main motor 38 is transmitted to the plate cylinder 10 via the printing cam 33,
And the printing pressure cam 33 are synchronously driven to rotate. A tension roller 54 that contacts the back surface of the main belt 51 and applies tension to the main belt 51 is disposed at an intermediate position between the lower pulley 49 and the upper pulley 50. The tension roller 54 is rotatably supported by a support shaft 54 a movably provided on a bracket (not shown) of the printer body 9.

On the right side of the plate cylinder driving means 24, a pressing force varying means 36 is arranged as shown in FIG. The pressing force varying means 36 includes a printing pressure control motor 55, a movable shaft 56, a rotating shaft 57, a worm wheel 58, a slit disk 59,
It has a sensor 60 and the like. The printing pressure control motor 55 capable of normal rotation and reverse rotation is attached to the printing apparatus main body 9 via a bracket (not shown), and a worm 61 is attached to its output shaft.

The other end of the tension spring 32 is attached to a movable shaft 56 which is supported by a groove (not shown) formed in a side plate (not shown) of the printer body 9 and is movable only in the front-rear direction of the paper transport direction X. Is attached, and an internal thread is formed in the inside. A shield plate 62 is integrally attached to the side surface of the movable shaft 56, and a sensor 63 that detects the shield plate 62 is attached to the vicinity of the shield plate 62 via a bracket (not shown). Has been done. The sensor 63 detects the shielding plate 62 at the home position where the printing pressure is in the standard state.

The rotary shaft 57 is rotatably supported by a support member (not shown) provided in the printer main body 9, and an external thread formed on the outer periphery of one end of the rotary shaft 57 to be screwed with a female thread formed on the movable shaft 56. A worm wheel 58 that meshes with the worm 61 is integrally attached to the rear of the worm wheel 58. A slit disk 59 is integrally attached to the other end of the rotary shaft 57, and a sensor 60 for sandwiching the slit disk 59 at a predetermined interval is arranged in the vicinity of the slit disk 59. With the operation of the printing pressure control motor 55,
The position of the movable shaft 56 is detected by detecting a predetermined number of pulses generated when the slit disk 59 is rotated by the sensor 60, whereby the biasing force of the actuating plate 31 by the tension spring 32, that is, the plate cylinder 10 is detected. The pressing force of the press roller 11 with respect to is controlled.

A plate making section 3 is arranged at the upper right portion of the printing apparatus main body 9. The plate making unit 3 includes a master holding member 64, a platen roller 65, a thermal head 66, and a cutting means 6.
7, master transport roller pair 68, 69, image memory 13
It has 6 mag. The master holding members 64 are respectively provided on the pair of side plates (not shown) of the printer body 9, and the master holding member 64 is formed by winding a master 70 in which a thermoplastic resin film and a porous support are bonded together in a roll shape. Both ends of the core portion 70b are rotatably and detachably supported.

A platen roller 65 provided on the left side of the master holding member 64 is rotatably supported by a side plate (not shown) of the printing apparatus main body 9 and is rotationally driven by a stepping motor (not shown). Platen roller 6
5, a thermal head 66 having a large number of heat generating elements is attached to a side plate (not shown) of the printing apparatus main body 9, and its heat generating element surface is pressed against the platen roller 65 by the biasing force of a biasing means (not shown). ing. The thermal head 66 selectively heats the heating elements while contacting the surface of the thermoplastic resin film of the master 70.
0 is subjected to hot melt perforation plate making.

A cutting means 67 is disposed on the left side of the platen roller 65 and the thermal head 66. Fixed blade 67 fixed to a frame (not shown) of the printer body 9
The cutting means 67 having a and a movable blade 67b movably supported by the fixed blade 67a has a well-known configuration for cutting the master 70 by rotationally moving the movable blade 67b with respect to the fixed blade 67a. .

On the left side of the cutting means 67, a pair of master conveying rollers 68, 69 is arranged. Each master transfer roller pair 68, 69 has a drive roller and a driven roller that are rotatably supported by a side plate (not shown) of the printer body 9, and each drive roller is driven by a platen roller 65 by a drive means (not shown). The driven rollers are rotationally driven in synchronism with, and each driven roller is pressed against the corresponding driving roller by a biasing means (not shown).

The image memory 136, which functions as a solid image detecting unit and a solid image ratio detecting unit, is provided on a base (not shown) in the printer body 9. Image memory 13
6, a RAM 13 functioning as an image memory described later.
The image data signal for one page stored in 5 is sent line by line and stored.

Below the plate making section 3, a sheet feeding section 4 is arranged. The paper feed unit 4 includes a paper feed tray 71 and a paper feed roller 7.
2, a separation roller pair 73, a registration roller pair 74, guide plates 75, 76, 77, 78 and the like. A paper feed tray 71 on which a large number of printing papers P can be stacked is supported by the printing apparatus main body 9 so as to be vertically movable, and is vertically moved by an elevating means (not shown).

Above the paper feed tray 71, a paper feed roller 72 having a high friction resistance member on its surface is arranged.
The paper feed roller 72 is rotatably supported by a bracket (not shown) that is swingably supported by the printing apparatus main body 9, and has a predetermined pressing force when the paper feed tray 71 is lifted by the elevating means. The uppermost printing paper P on 71 is pressed. The paper feed roller 72 is rotationally driven by a paper feed drive means (not shown).

To the left of the paper feed roller 72, there is provided a separation roller pair 73 consisting of an upper roller 73a and a lower roller 73b each having a high friction resistance member on its surface. The upper roller 73a is drivingly connected to the sheet feeding roller 72 via a driving force transmitting unit such as a gear or a belt, and is rotationally driven in the same direction in synchronization with the rotational driving of the sheet feeding roller 72. The lower roller 73b is pressed against the upper roller 73a by the urging force of an urging means (not shown), and is rotatable only in the same direction as the upper roller 73a.

A registration roller pair 74 is arranged on the left side of the separation roller pair 73. Registration roller pair 74 including a driving roller 74a and a driven roller 74b
The driving roller 74a is rotated at a predetermined timing synchronized with the plate cylinder 10 by transmitting the rotational driving force from the plate cylinder driving means 24 by a driving force transmission means (not shown) such as a gear or a cam. The printing paper P is fed toward the printing unit 2 by the driven roller 74b pressed against the printing paper 74a.

Guide plates 75 and 76 are arranged between the separation roller pair 73 and the registration roller pair 74.
Each of the guide plates 75 and 76 is fixed to a side plate (not shown) of the printing apparatus main body 9, and each of the guide plates 75 and 76 constitutes the first half of the paper feed path for the printing paper P.
Guide plates 77 and 78 are disposed between the registration roller pair 74 and the printing unit 2. Each of the guide plates 77 and 78 is fixed to a side plate (not shown) of the printing apparatus main body 9, and each of the guide plates 77 and 78 constitutes the latter half of the paper feed path for the printing paper P.

A plate discharge unit 5 is arranged on the upper left side of the printing unit 2. The plate discharging unit 5 includes an upper plate discharging member 79 and a lower plate discharging member 8.
0, a plate discharge box 81, a compression plate 82, and the like. The upper plate discharging member 79 includes a driving roller 83 and a driven roller 8.
4. The endless belt 85 has the endless belt 85 and the like, and the drive roller 83 is rotationally driven in the clockwise direction in the drawing by the plate discharge driving means (not shown), so that the endless belt 85 moves in the arrow direction in the drawing. The lower plate discharge member 80 includes a drive roller 86, a driven roller 87, an endless belt 88, and the like, and the drive roller 8
The driving force of the plate discharge driving means (not shown) for rotating 3 is transmitted by the driving force transmitting means (not shown) such as a gear or a belt, so that the driving roller 86 is driven to rotate in the counterclockwise direction in the figure, thereby endlessly moving. The belt 88 moves in the direction of the arrow in the figure. Further, the lower plate discharging member 80 is movably provided by a moving unit (not shown), and a position shown in the drawing and a position where the endless belt 88 located on the outer peripheral surface of the driven roller 87 contacts the outer peripheral surface of the plate cylinder 10. Are selectively positioned.

The plate discharge box 81 for storing the used master is provided so as to be detachable from the printer body 9. A compression plate 82 for pushing the used master carried by the upper plate discharging member 79 and the lower plate discharging member 80 into the plate discharging box 81 is supported by the printing apparatus main body 9 so as to be vertically movable, and is vertically moved by an elevating means (not shown). To be done.

Below the plate discharge unit 5, a paper discharge unit 6 is arranged. The paper discharge unit 6 has a peeling member 89 as a peeling unit, a paper discharge guide plate 90, a paper discharge conveying member 91, a paper discharge tray 92, and the like. The peeling member 89 has a peeling claw 93, an air knife 94, and the like. The peeling claw 93 is swingably supported by the printing apparatus main body 9, and the tip thereof is close to the outer peripheral surface of the plate cylinder 10 by a claw swinging device (not shown) and an obstacle such as a clamper 23. In order to avoid the above, the front end is selectively positioned at a position separated from the outer peripheral surface of the plate cylinder 10. The claw swinging means (not shown) transmits the driving force from the plate cylinder driving means 24 by a driving force transmitting means (not shown), and swings the peeling claw 93 in synchronization with the plate cylinder 10.

As shown in FIG. 4, the air knife 94 has an air knife main body 95 and two fans 96.
The air knife main body 95 has a closed casing shape,
Two air outlets 95a are provided on one side thereof. Each air outlet 95a is divided into two parts at the center, and a notch 95b is formed in the center for preventing the peeling claw 93 from interfering with the air knife main body 95 when swinging. The fans 96, which can change the amount of blown air and function as wind force changing means, are arranged inside the air knife main body 95, respectively, and the blower openings 96a are arranged so as to face the air blowout openings 95a.

Below the peeling member 89, the printer body 9 is provided.
A paper discharge guide plate 90 fixed to the side plate of the paper is disposed. The discharge guide plate 90 is pressed against the outer peripheral surface of the plate cylinder 10 by the press roller 11 to transfer the ink, and
The printing paper P that has been peeled from the outer peripheral surface of the plate cylinder 10 by the peeling member 89 is received and guided toward the paper discharge conveyance member 91.

The paper discharge / conveyance member 91 includes a driving roller 97,
Driven roller 98, endless belt 99, suction fan 100
And so on. The drive roller 97 is rotatably supported by a unit side plate (not shown), and is rotationally driven by a paper discharge drive means (not shown). The driven roller 98 is also rotatably supported by the same side plate, and a plurality of endless belts 99 having a plurality of openings are stretched around the drive roller 97 and the driven roller 98. The suction fan 1 is provided below the drive roller 97, the driven roller 98, and the endless belt 99.
00 is provided. The paper discharge conveyance member 91 sucks the print paper P onto the endless belt 99 by the suction force of the suction fan 100, and conveys the print paper P in the direction of the arrow in the figure by the rotation of the drive roller 97. The paper discharge tray 92 for stacking the print paper P conveyed by the paper discharge conveyance member 91 on the upper surface thereof is one end fence 101 movable in the paper conveyance direction and a pair of side fences 102 movable in the paper width direction. And have.

An image reading section 7 is arranged above the printer body 9. The image reading unit 7 includes an original receiving tray 103 on which an original is placed and a contact glass 10 on which an original is placed.
4, a pair of document transport rollers 105 for transporting a document, a document transport roller 106, guide plates 107, 108 for guiding the document to be transported, a plurality of document transport belts 109 for transporting the document along the contact glass 104, read A switching plate 110 for switching the direction in which the original is ejected, and a pressure plate 11 that supports the above-mentioned members except the contact glass 104 and is provided so as to be able to come into contact with and separate from the contact glass 104
1. Reflecting mirrors 112, 1 for scanning and reading an original image
13 and a fluorescent lamp 114, a lens 115 that focuses the scanned image, an image sensor 116 such as a CCD that processes the focused image, and the like.

FIG. 5 shows the operation panel of the stencil printing apparatus 1. An operation panel 117 provided on the upper front surface of the printing apparatus main body 9 has a plate making start key 118, a print start key 119, a test printing key 120, a continuous key 121, a clear / stop key 122, and a numeric keypad 12 on its upper surface.
3, a display key 12 including an enter key 124, a program key 125, a mode clear key 126, a print speed setting key 127, a four-direction key 128, and a 7-segment LED.
9, a display device 130 including an LCD, a press contact force switching key 131 for changing the press contact force of the press roller 11 with respect to the plate cylinder 10, and the like.

The plate-making start key 118 is the stencil printing machine 1.
When the plate making operation is performed on the plate making operation, and when the plate making start key 118 is pressed, the plate making operation is performed after the plate discharging operation and the document reading operation, and then the plate making operation is performed and the stencil printing apparatus 1 Is in the print standby state. The print start key 119 is pressed to cause the stencil printing apparatus 1 to perform a printing operation, and the stencil printing apparatus 1 enters a print standby state and various printing conditions are set, and then the print start key 119 is pressed to perform the printing operation. Done. The test printing key 120 is pressed when the stencil printing apparatus 1 performs test printing, and the test printing key 120 is pressed after various conditions are set, so that only one sheet is printed. The continuous key 121 is pressed before pressing the plate making start key 118 when the plate making operation and the printing operation are continuously performed.
When the plate making start key 118 is pressed after the printing conditions are input after pressing 21, the plate discharge operation, the document reading operation,
The printing operation is performed subsequent to the plate making operation.

The clear / stop key 122 is pressed when stopping the operation of the stencil printing apparatus 1 or when clearing the number of characters, and the ten key 123 is used for inputting a numerical value. The enter key 124 is pressed when deciding a numerical value or the like at the time of various settings, the program key 125 is pressed when registering or calling a frequently-used operation, and the mode clear key 126
Is pressed to clear various modes and return to the initial state. The print speed setting key 127 is pressed when setting the print speed prior to the printing operation, and when the dark image is desired or when the ambient temperature is low, the print speed is slow and the thin image is desired. If the ambient temperature is high, the printing speed is set high. 4 direction key 128 is up key 1
28a, down key 128b, left key 128c, right key 12
8d, and is pressed when adjusting the image position at the time of editing the image or when selecting numerical values or items at the time of various settings.

Display device 12 comprising 7-segment LED
9 mainly displays numbers such as the number of printed sheets. In the initial state, the display device 130 composed of an LCD displays an original type setting display 130a and a scaling setting display 130 as shown in FIG.
b, paper type setting display 130c, position adjustment setting display 13
0d is displayed, and corresponding selection / setting keys 130A, 130B, 130C, 130 are provided below each display.
D is provided. The display device 130 has a hierarchical display structure, and the selection setting key 13 is selected from the state shown in FIG.
When 0A is pressed, a document type setting mode for selecting and setting a character mode, a photo mode or the like as a document image mode, and a scaling setting for selecting and setting automatic scaling or independent scaling when the selection setting key 130B is pressed Mode, select setting key 13
When 0C is pressed, the mode is set to the paper type setting mode in which standard paper or thick paper is set as the printing paper to be used, and in the position adjustment setting mode in which the image forming position is adjusted when the selection setting key 130D is pressed. , Display device 13
The display of 0 changes corresponding to each mode.

The pressure contact force switching key 126 is pressed when the printing density for the printing paper P is switched in combination with the printing speed setting key 127. When the press contact force of the press roller 11 with respect to the plate cylinder 10 is increased, a dark image is transferred to the printing paper P, and when the press contact force of the press roller 11 with respect to the plate cylinder 8 is weakened, a thin image is transferred to the print paper P.

FIG. 6 is a block diagram of the control means used in the stencil printing machine 1. This control means 132
Has a CPU 133, a ROM 134, and a RAM 135 inside.
It is a well-known microcomputer having a printer, and is provided inside the printer main body 9. The control means 132
Whether or not the image read by the image reading unit 7 has a solid image, and if it has a solid image, the image ratio thereof is detected, and it is set in advance according to the detected solid image ratio. It has a function of selecting a predetermined printing speed, a pressing force of the press roller 11 and a wind force of the peeling member 89 from the control pattern table, and controlling the operation of each driving means.

The CPU 133, based on various signals from the operation panel 117, detection signals from various sensors provided in the printing apparatus main body 9 and the operation program called from the ROM 134, the printing unit 2, the plate making unit 3, and the paper feeding unit. Part 4,
The operation of each drive unit provided in the plate discharge unit 5, the sheet discharge unit 6, and the image reading unit 7 is controlled to control the overall operation of the stencil printing apparatus 1. Further, when the original image is read by the image reading unit 7, it is determined whether the read image is a solid image based on the image data signal sent from the image memory 136.

The ROM 134 stores the operation program of the stencil printing apparatus 1 as a whole, and it is preliminarily stored according to the solid image ratio (the ratio of the solid image area to the effective printing area) detected as described above. A plurality of set control pattern tables are stored. The stored control pattern table is the print speed control pattern table shown in FIG. 7, the air volume control pattern table shown in FIG.
9 is a printing pressure control pattern table shown in FIG. 9. In this example, the thresholds of the solid image ratio are set at two positions, 15% and 45%, and the printing speed is set when the solid image ratio exceeds each threshold value. And the air volume and the printing pressure are controlled to be changed.

The printing speed control pattern table reduces the printing speed as the solid image rate increases, and the air volume control pattern table increases the air volume as the solid image rate increases. The pattern tables are set so as to decrease the printing pressure as the solid image ratio increases. This is because when the solid image ratio increases and "rolling up" is likely to occur, the printing speed is decreased and the air volume is increased to blow strong wind force on the printing paper P for a long time to promote peeling, This is because an increase in the amount of ink seeping out from the plate cylinder 10 due to a decrease in printing speed is suppressed by reducing the printing pressure.

The RAM 135 has a function of temporarily storing the calculation result of the CPU 133, a function of storing data signals and ON / OFF signals set and input from various keys and various sensors on the operation panel 117, and an image. When the reading unit 7 reads a document image, it also functions as an image memory for storing the read image data signal. This function will be described later.

The operation of the stencil printing machine 1 will be described below based on the above configuration. The operator opens the pressure plate 111, places the document to be printed on the contact glass 104, and then closes the pressure plate 111 again. Then, after setting the plate making conditions with various keys on the operation panel 117, the plate making start key 118 is pressed.

When the plate making start key 118 is pressed,
The image reading unit 7 performs a reading operation of a document image. The reading of the original image is performed by reflecting the reflected light exposed by the fluorescent lamp 114 by the reflection mirrors 112 and 113, and the read original image is focused by the lens 115 and then incident on the image sensor 116 to be photoelectrically converted. To be converted. The photoelectrically converted electric signal is input to an A / D converter (not shown) in the printer body 9, and then stored as an image data signal in the RAM 135 functioning as an image memory. One page of the original ((1
An image data signal of a plate is stored.

When the original is automatically conveyed without opening the pressure plate 111, the plate-making start key 118 is depressed with the original placed on the original tray 103. Then, the document transport roller pair 105 starts rotating, and the topmost one of the documents (not shown) is transported onto the contact glass 104, and the image is read in the same manner as described above. The document from which the image has been read is discharged by a document transport belt 109 and a document transport roller 106 to a document tray (not shown) arranged above the document transport belt 109.

In parallel with the image reading operation in the image reading section 7, the plate discharging section 5 performs a plate discharging operation for peeling the used master from the outer peripheral surface of the plate cylinder 10. Plate-making start key 11
When 8 is pressed, the plate cylinder 10 starts to rotate, and when the tip of the used master on the outer peripheral surface reaches a predetermined plate discharge position corresponding to the endless belt 88 on the outer peripheral surface of the driven roller 87, The rotation of 10 is stopped. After that, the plate discharge driving means and the moving means are actuated, the respective drive rollers 83, 86 rotate, and the lower plate discharge member 80 moves to the plate cylinder 10 side. When the endless belt 88 located on the outer peripheral surface of the driven roller 87 comes into contact with the used master, the plate cylinder 10 rotates again, and the used master picked up by coming into contact with the endless belt 88 has the lower plate discharging member 80 and the upper plate discharged. It is sandwiched by the member 79 and separated from the outer peripheral surface of the plate cylinder 10. The separated used master is conveyed by the lower plate discharge member 80 and the upper plate discharge member 79 and is discarded in the plate discharge box 81, and then the compression plate 82.
Compressed by.

Even after all the used masters have been peeled off from the outer peripheral surface, the plate cylinder 10 continues to rotate and rotates to a predetermined plate feed standby position and stops. When the plate cylinder 10 stops at the plate supply standby position, the opening / closing means (not shown) is activated to open the clamper 23, and the stencil printing apparatus 1 enters the plate supply standby state.

When the stencil printing machine 1 is in the plate supply standby state after the plate discharge operation is completed, the platen roller 65 and the respective master transport roller pairs 68, 69 are rotationally driven to pull out the master 70 from the master roll 70a. Then, when the image forming area of the master 70 reaches the position corresponding to the heating element of the thermal head 66, after the image data signal stored in the RAM 135 is subjected to image processing (magnification processing, cutting processing, etc.). It is temporarily stored in the image memory 136 for each line address. During this storage, it is determined whether the image data signal stored in the image memory 136 is a solid image, which will be described later. Next, the image data signals stored in the image memory 136 are sequentially called, and a thermal head driver (not shown) selectively causes each heating element of the thermal head 66 to generate heat based on the called image data signal,
As a result, a plate-making image is formed on the thermoplastic resin film surface of the master 70. The master 70 is sent to the clamper 23 while forming a plate-making image, and when the leading end of the master 70 reaches a predetermined position where it can be held by the clamper 23, the opening / closing means (not shown) is actuated to close the clamper 23, and the master 70 has its tip The part is held on the plate cylinder 10.

Thereafter, the plate cylinder 10 is rotationally driven in the clockwise direction in FIG. 1 at the same peripheral speed as the conveying speed of the master 70, and the winding operation of the master 70 on the plate cylinder 10 is performed. Then, when the image data signal from the image memory 136 is cut off, the operation of the thermal head 66 is stopped, and when the master 70 for one plate is conveyed by plate making, the rotation of the platen roller 65 and the master conveying roller pairs 68, 69 is stopped. At the same time, the movable blade 67b rotationally moves to cut the master 70. The cut master 70 is pulled out from the plate making unit 3 by the rotation of the plate cylinder 10, and the plate cylinder 10 is rotated to the home position and stopped to complete the plate making operation and the plate feeding operation.

A method of determining whether the image data signal stored in the image memory 136 is a solid image will be described. When the image data signal is stored in the image memory 136 for each line address, if the black data 137 exists at the same address value of the next line as shown in FIG. When the area of the integrated black data 137 reaches the specified area, the control unit 132 recognizes this image as a solid image.

As for the area for determining whether or not the image is a solid image, in the present embodiment, as shown in FIG. 11, the image exists at a position up to 5 cm from the leading edge of the paper (if a part thereof exists). Is set to 20 cm ² or more, and when the image exists at a position exceeding 5 cm from the leading edge of the paper, it is set to 25 cm ² or more. This is because if a continuous image of black data 137 is present in a portion near the leading edge of the sheet during paper ejection, "rolling up" is likely to occur, so the criteria for recognizing a solid image in the portion near the leading edge of the sheet is strict. There is. The distance from the leading edge of the paper and the judgment reference area shown in this embodiment differ depending on the mechanism of the stencil printing apparatus, the type of ink used, the paper size, and the like, and thus these numerical values are set arbitrarily. Further control means 1
At 32, the CPU 133 calculates the total area of the detected solid image, and based on this, the CPU 133 calculates the solid image ratio which is the ratio of the solid image in the total image area. The calculated solid image ratio is stored in the RAM 135.

After the plate feeding operation, the printing operation is performed. When the plate cylinder 10 stops at the home position, the paper feed roller 72, the upper roller 73a, the drive roller 97, and the suction fan 100 are driven, respectively, and the plate cylinder 10 is rotationally driven at a low speed in the clockwise direction in FIG. The uppermost one sheet of the printing paper P stacked on the paper tray 71 is pulled out, and the leading end thereof is nipped by the pair of registration rollers 74. The leading end of the image area of the master 70 wound on the plate cylinder 10 in the plate cylinder rotation direction is the press roller 11.
The drive roller 74a is rotationally driven at a predetermined timing to reach the position corresponding to, and the pulled-out printing paper P is fed between the plate cylinder 10 and the press roller 11. Almost at the same time as the rotation of the driving roller 74a, the contact state between the large diameter portion and the cam follower 35 is released by the rotation of the printing pressure cam 33, and the press roller 11 presses the outer peripheral surface of the printing drum 11 with a press contact force that provides a standard printing pressure. The outer peripheral surface of 10 is pressed.

The printing paper P fed by the pair of registration rollers 74 is transferred by the press roller 11 to the plate cylinder 10.
The master 70 wound around is pressed. By this pressing operation, the press roller 11, the printing paper P, the master 70, and the plate cylinder 10 are brought into pressure contact with each other, and the ink supplied from the ink roller 19 to the inner peripheral surface of the plate cylinder 10 oozes out from the openings of the plate cylinder 10. , The porous support plate (not shown) and the mesh screen (not shown) of the plate cylinder 10, and the printing paper P through the perforated portion of the master 70 after being filled in the porous support of the master 70.
Is transferred to, and so-called printing is performed.

Printing paper P on which an image has been transferred by printing
Is peeled off from the outer peripheral surface of the plate cylinder 10 by the tip of the peeling claw 93 and the wind force of the air knife 94, falls downward, is guided by the paper discharge guide plate 90, and is sent to the paper discharge conveying member 91. The printing paper P sent to the paper discharge conveyance member 91 is conveyed to the left while being attracted to the upper surface of the endless belt 99 by the suction force of the suction fan 100, and is discharged to the paper discharge tray 92.
Discharged on top. After that, the plate cylinder 10 is again rotated to the home position and stopped, and the stencil printing apparatus 1 is in a printing standby state after the plate-making operation is completed.

After the stencil printing apparatus 1 is in the print standby state, the test printing key 120 is pressed after various printing conditions such as the number of printed sheets, the type of paper, the printing speed, and the printing pressure are input, and the trial printing is performed. Be seen. When the test print key 120 is pressed, the CPU 133 determines whether or not a solid image is detected during image reading, that is, whether or not the solid image ratio is stored in the RAM 135.

When a solid image is not detected, the plate cylinder 10 is rotationally driven at the set printing speed, and one printing sheet P is fed from the sheet feeding section 4. The fed printing paper P is temporarily retained by the pair of registration rollers 74, and then fed at the same timing as that at the time of plate making, and is pressed against the outer peripheral surface of the plate cylinder 10 with the printing pressure set by the press roller 11. It The printing paper P on which the image is transferred has a tip of the peeling claw 93 and an air knife 94 set to a standard air volume.
Is separated from the outer peripheral surface of the plate cylinder 10 and is conveyed by the sheet discharge conveying member 91 to be discharged onto the sheet discharge tray 92.

If a solid image is detected, CP
U133 calls the solid image ratio stored in the RAM 135 and also calls the printing speed control pattern table, the printing pressure control pattern table, and the air volume control pattern table stored in the ROM 134, respectively, and the main motor 3
8, the printing pressure control motor 55, and the operation of the fan 96 are respectively controlled to rotate the peripheral speed (printing speed) of the plate cylinder 10 and the movable shaft 5 according to each pattern table based on the solid image ratio.
The position of 6 (printing pressure) and the number of rotations of the fan 96 (air volume) are determined. After that, when the printing pressure control motor 55 rotates and the movable shaft 56 is positioned at a predetermined position, the main motor 38 is rotationally driven at a predetermined rotation speed, and at the same time, one sheet of printing paper P is fed from the paper feeding unit 4. Will be sent. Printed paper P fed
Is temporarily stopped by the pair of registration rollers 74 and then fed at the same timing as that for plate making.
Is pressed against the outer peripheral surface of the plate cylinder 10 with a predetermined printing pressure.
The printing paper P to which the image has been transferred is printed by the tip of the peeling claw 93 and the air knife 94 set to a predetermined air volume to the plate cylinder 1.
The sheet is separated from the outer peripheral surface of No. 0, is conveyed by the sheet discharge conveying member 91, and is discharged onto the sheet discharge tray 92.

When the position or density of the image is confirmed by test printing, and the print start key 119 is pressed after the number of prints is displayed on the display device 129 by the ten keys 123, the print paper P is fed from the paper feed unit 4. The sheets are continuously fed and the printing operation is performed under the same conditions as in the test printing.

With the above-described structure, the control unit 132 controls the printing speed and printing pressure and the wind force of the air knife 94 based on the presence or absence of a solid image detected during image reading and the solid image ratio. The peeling of the paper can be performed under the optimum condition according to the image, and the occurrence of "roll-up" can be effectively prevented, so that a large amount of good printed matter can be obtained. Further, it is possible to accelerate drying of the transferred ink at the same time as peeling by the wind force, and it is possible to prevent the occurrence of set-off on the next printing paper.

In the above-described embodiment, the wind speed of the air knife 94 is controlled together with the printing speed and the printing pressure at the time of trial printing and printing. However, when fine control is not desired, the wind force of the air knife 94 is kept constant. It is possible to prevent the occurrence of "roll-up" only by controlling the printing speed and printing pressure. Further, in the above-described embodiment, the printing speed and the printing pressure selected by the control unit and the wind force of the air knife 94 are used during printing in the same manner as during trial printing, but "roll-up" may occur during trial printing. When the printing density is different, the printing speed setting key 127 and the press contact force switching key 131 are used to change the printing density at the time of printing, and the printing speed and printing pressure at the time of test printing are further increased or decreased. May be.

In the above embodiment, the presence or absence of a solid image and the solid image ratio are detected at the time of image reading, and the printing speed, the printing pressure, and the wind force of the air knife 94 are controlled based on the detected solid images. A mode setting key for setting whether or not to detect a solid image and a solid image ratio is provided. When this mode is set, the same control as above is performed, and when this mode is not set, It may be configured to perform the same control as a normal stencil printer. Further, in the above-described embodiment, the printing speed, the printing pressure, and the wind force of the air knife 94 are controlled stepwise according to the solid image ratio, but the solid image ratio is not detected and only the presence or absence of the solid image is detected. You may employ | adopt the structure which controls printing speed, printing pressure, and the wind force of the air knife 94 in two steps, respectively.

In the above embodiment, the image reading unit 7 reads the image and detects the presence or absence of the solid image and the solid image ratio of the read image. However, the image sent from the personal computer and the scanner are read. It may be configured to detect the presence / absence of a solid image and the solid image ratio of an image transmitted from an external device, such as a mixed image. In this case, the external device functions as the image reading unit. Further, although the air knife 94 is exemplified as the air knife in the present embodiment, the air knife is not limited to this, and any form can be used as long as it blows air between the outer peripheral surface of the plate cylinder and the printing paper to be peeled off. You may use the thing of.

[0077]

According to the present invention, the printing speed and the printing pressure are controlled on the basis of the presence or absence of a solid image detected during image reading or the solid image ratio. Therefore, the printing paper is separated from the plate cylinder. Can be performed under optimum conditions according to the image, and it is possible to effectively prevent the occurrence of "rolling up", and it is possible to obtain a large amount of good printed matter. Further, by controlling the wind speed of the peeling means having an air knife in addition to the printing speed and printing pressure, finer control can be performed, and the occurrence of "rolling up" can be prevented more effectively. . Further, whether or not the image is a solid image is determined based on the area of the image, and the threshold value for determining whether or not the image is a solid image is changed according to the distance from the leading edge side of the printing paper. Since the standard is tightened near the side, the occurrence of "rolling up" can be prevented more effectively.

[Brief description of drawings]

FIG. 1 is a schematic front view of a stencil printing machine adopting an embodiment of the present invention.

FIG. 2 is a perspective view illustrating plate cylinder driving means used in an embodiment of the present invention.

FIG. 3 is a perspective view illustrating a swinging unit and a pressing force varying unit used in an embodiment of the present invention.

FIG. 4 is a perspective view illustrating an air knife used in an embodiment of the present invention.

FIG. 5 is a schematic view of an operation panel used in an embodiment of the present invention.

FIG. 6 is a block diagram of control means used in an embodiment of the present invention.

FIG. 7 is a diagram showing a printing speed control pattern table used in an embodiment of the present invention.

FIG. 8 is a diagram showing an air volume control pattern table used in an embodiment of the present invention.

FIG. 9 is a diagram showing a printing pressure control pattern table used in an embodiment of the present invention.

FIG. 10 is a schematic diagram for explaining whether or not a solid image is detected by a solid image detection unit used in an embodiment of the present invention.

FIG. 11 is a schematic diagram for explaining whether or not a solid image is detected by a solid image detection unit used in an embodiment of the present invention.

[Explanation of symbols]

1 Stencil printing device 3 Plate making section 4 Paper feeding section 7 Image reading section 10 Plate cylinder 11 Pressing means (press roller) 36 Pressing force varying means 38 Printing speed varying means (main motor) 70 Master 89 Peeling means (peeling member) 94 Air knife 132 control means 134 solid image detection means, solid image ratio detection means (image memory) P printing paper

Claims (6)

[Claims] 1. An image reading unit for reading an original image, a plate making unit for making a master on the basis of the image read by the image reading unit, and a plate cylinder for winding the master made by the plate making unit. A paper feeding unit for feeding the printing paper, a pressing unit for pressing the printing paper fed from the paper feeding unit against the plate cylinder, and a peeling unit for peeling the printing paper from the plate cylinder with an air knife. In a stencil printing apparatus having a solid image detecting means for detecting whether or not there is a solid image in the original image, a printing speed varying means for changing the rotational peripheral speed of the plate cylinder, and the pressing against the plate cylinder. Pressing force varying means for changing the pressing force of the means, and when the solid image is detected by the solid image detecting means, the rotation speed of the plate cylinder is changed by the printing speed changing means. Predetermined value Stencil printing machine, characterized by said pressing force varying means sets the setting the ink transfer amount to the printing paper from the plate cylinder to a predetermined value. 2. When the solid image is detected in the original image by the solid image detecting means, the peripheral speed of rotation of the plate cylinder is reduced and the amount of ink transfer from the plate cylinder to the printing paper is reduced. The stencil printing machine according to claim 1, further comprising control means for controlling the printing speed varying means and the pressing force varying means. 3. A solid image ratio detecting means for detecting a proportion of the solid image in the original image, wherein the control means varies the printing speed varying means and the pressing force varying in accordance with the detected proportion. The stencil printing machine according to claim 2, wherein the means is controlled. 4. The stencil printing apparatus according to claim 3, wherein the wind force of the peeling means is variable, and the control means changes the wind force according to the ratio. 5. The solid image detecting means determines whether or not an arbitrary image is a solid image based on the area of the image, and the threshold value for determining whether or not the image is a solid image is the printing. 5. The change according to the distance from the leading edge side of the sheet, according to claim 1.
The stencil printing machine described in 1. 6. The stencil printing apparatus according to claim 5, wherein the threshold value increases as the distance from the front end side of the printing paper increases.