JP4750438B2 - Printing device - Google Patents

Description

  The present invention is a printing apparatus such as a stencil printing machine having a plurality of plate cylinders, and in particular, transmits a driving force applied to one plate cylinder to the other plate cylinder to drive each plate cylinder. The present invention relates to a printing apparatus capable of adjusting a printing speed.

  Conventionally, printing apparatuses have been used for the purpose of printing a large number of sheets. As a printing apparatus, for example, a stencil printing apparatus is known. As a stencil printing apparatus, a rotatable plate cylinder having a structure in which a plurality of mesh screens made of resin or metal mesh are wound around a porous support cylinder and a thickness of about 1 to 3 μm is generally used. Using a plastic stencil and a stencil master with a laminated structure in which a commonly used porous support made of Japanese paper fiber, synthetic fiber, or a mixture of Japanese paper and synthetic fiber is used, the film surface of this master is thermally treated. It is heated and perforated with a head, wound around the plate cylinder, supplied with ink from an ink supply member provided inside the plate cylinder, and continuously pressed against the plate cylinder by pressing means such as a press roller. A heat-sensitive digital stencil printing apparatus that performs printing by allowing ink to ooze out from a plate cylinder opening part and a master punching part is well known.

  In recent years, in such a printing apparatus, as a method for performing multicolor printing for presentations or the like, a printing method has been adopted in which printing is performed while replacing a plurality of plate cylinders for each color ink. However, in such a printing method, in order to print for each color of ink, it is necessary to realign the stacked paper sheets and set them again in the paper feeding unit, and there is a problem that the printing work is troublesome. there were. In addition, there is also a problem that cleaning is necessary because the ink transferred to the printed paper adheres and accumulates on the paper transporting portion at the time of refeeding. In addition, when trying to prevent such contamination of the transport unit, there is a problem that time is required for drying the ink and efficiency is poor.

Therefore, as described in [Patent Document 1] and [Patent Document 2], a printing apparatus that includes a plurality of plate cylinders and is capable of performing multicolor printing with a single sheet is proposed. .
In such a printing apparatus, it is necessary to match the position for printing on the paper by each plate cylinder. Here, when the paper transport direction is the left-right direction and the direction perpendicular to the paper transport direction is the vertical direction, the vertical alignment can be performed by moving each plate cylinder itself in its axial direction. Direction alignment can be performed by adjusting the phase between the plate cylinders.

Further, in a printing apparatus having a plurality of plate cylinders, it is general that the driving force applied to one plate cylinder is transmitted to the other plate cylinder to drive each plate cylinder. .
On the other hand, as described in [Patent Document 3] and the like, a printing apparatus capable of adjusting the printing speed has been proposed. Note that the printing apparatus described in [Patent Document 3] is a single cylinder type printing apparatus having a single plate cylinder, and includes a mechanism for adjusting the phase of the plate cylinder when the printing speed is adjusted. Yes.

JP 2001-219635 A Japanese Patent Laid-Open No. 10-297074 JP-A-2-220880

However, in the printing apparatus in which the driving force applied to one plate cylinder is transmitted to the other plate cylinder to drive each plate cylinder and the printing speed can be adjusted, the printing speed is changed. Sometimes, there is a problem that displacement occurs in the left-right direction.
That is, for example, when the configuration in which the driving force applied to one plate cylinder is transmitted to the other plate cylinder is configured with a belt or gear, when the printing speed is changed, the load applied to the configuration is increased. The phase of the other plate cylinder is delayed due to fluctuation, deformation of the belt, deformation of the member such as a shaft, and the like. As a result, the printing position by the other printing cylinder becomes the printing position by the one printing cylinder. There is a problem of shifting to the upstream side in the paper transport direction.

In addition, when such a shift occurs, there arises a problem that a ghost image is generated.
That is, when printing is repeatedly performed on one and the other plate cylinders, the ink printed on the sheet by the upstream plate cylinder in the sheet conveyance direction is transferred to the downstream plate cylinder and accumulated. If the phase of these plate cylinders does not change, no ghost image is generated even if the ink transferred to the downstream plate cylinder adheres to the paper again. However, if the printing positions of the upstream and downstream plate cylinders are shifted due to the above-described causes, and the ink transferred to the downstream plate cylinder adheres to the paper again, the print image by the upstream plate cylinder is moved from the original printing position. A ghost image is also generated at a shifted position.

  Such a problem can be solved by moving to a mode for adjusting the print position when adjusting the printing speed and performing a test print while adjusting the print speed. Problems such as troublesome work, time-consuming work, and wasted paper for trial printing.

  The present invention is a printing apparatus, such as a stencil printing apparatus, having a plurality of plate cylinders, which transmits a driving force applied to one plate cylinder to the other plate cylinder to drive each plate cylinder and print speed Therefore, an object of the present invention is to provide a printing apparatus that can adjust the printing speed and that does not cause a deviation in printing position even when the printing speed is adjusted.

In order to achieve the above object, the invention according to claim 1 is directed to the first plate cylinder and the second plate cylinder, the drive means for driving the first plate cylinder, and the first plate cylinder by the drive means. Driving force transmitting means for driving the second printing cylinder by transmitting the applied driving force to the second printing cylinder, and driving speed adjusting means for adjusting the driving speed of the first printing cylinder and the second printing cylinder And a printing position adjusting means for adjusting a relative position between a first printing position that is a printing position on the sheet by the first plate cylinder and a second printing position that is a printing position on the sheet by the second plate cylinder; the have a control means for the driving speed by the driving speed adjusting means for adjusting the relative position by the printing position adjusting means when it is adjusted, the control means, when said driving speed is high, when the slow Compared to the paper transport direction, the second print position is on the downstream side. By shifting and / or the first printing position Las upstream, in the printing device for adjusting the relative position.

  According to a second aspect of the present invention, in the printing apparatus according to the first aspect, the printing position adjusting means includes a phase adjusting means for adjusting a phase between the first plate cylinder and the second plate cylinder. Features.

  According to a third aspect of the present invention, in the printing apparatus according to the second aspect, the driving force transmitting means includes an endless belt that engages with the first plate cylinder and the second plate cylinder and rotates integrally therewith, The phase adjusting means has a phase adjusting member that adjusts the phase by changing the engagement position between the endless belt and the first plate cylinder and / or the second plate cylinder by being displaced by the control means. It is characterized by.

  According to a fourth aspect of the present invention, in the printing apparatus according to any one of the first to third aspects, the printing position adjusting means is a plate making position to the first master wound around the first plate cylinder. And a relative position of the plate making position to the second master wound around the second plate cylinder.

The present invention relates to a first plate cylinder, a second plate cylinder, a driving unit for driving the first plate cylinder, and a driving force applied to the first plate cylinder by the driving unit. A driving force transmitting means for driving the second printing cylinder to transmit to the printing plate, a driving speed adjusting means for adjusting the driving speed of the first printing cylinder and the second printing cylinder, and printing on the paper by the first printing cylinder. A printing position adjusting unit that adjusts a relative position between a first printing position that is a position and a second printing position that is a printing position for a sheet by the second plate cylinder; and the driving speed is adjusted by the driving speed adjusting unit. is to have a control means for adjusting the relative position by the printing position adjustment means when said control means, when said driving speed is high, than when slow, in the conveying direction of the sheet, the second And / or the first printing position is shifted to the downstream side. By shifting the flow side, since the printing apparatus for adjusting the relative position, a first printing position and a second printing position caused by a change in the driving load on the driving force transmission means when adjusting the printing speed By offsetting the relative position change in consideration of the direction of the relative position change that occurs in the driving force transmission means, it is possible to satisfactorily prevent the printing position from being shifted before and after adjusting the printing speed, and to prevent the occurrence of ghost images Thus, it is possible to provide a printing apparatus that can easily perform high-quality printing.

  If the printing position adjusting means has phase adjusting means for adjusting the phase between the first plate cylinder and the second plate cylinder, the drive applied to the driving force transmitting means when the printing speed is adjusted. By offsetting the change in the relative position between the first printing position and the second printing position caused by the change in the load by adjusting the phase between the first printing cylinder and the second printing cylinder, the printing speed Thus, it is possible to provide a printing apparatus that does not cause a shift in the printing position before and after the adjustment, and that can easily perform high-quality printing by preventing generation of a ghost image.

  The driving force transmission means has an endless belt that engages with the first plate cylinder and the second plate cylinder and rotates integrally, and the phase adjusting means is displaced by the control means, thereby the endless belt. And the first plate cylinder and / or the second plate cylinder change, and the phase adjusting member for adjusting the phase is provided, the driving force transmitting means is applied when the printing speed is adjusted. By adjusting the phase of the first plate cylinder and the second plate cylinder with a relatively simple configuration, the relative position change between the first printing position and the second printing position caused by the change in the driving load is adjusted. By canceling out, it is possible to provide a printing apparatus in which the printing position is not shifted before and after the adjustment of the printing speed, and a ghost image is prevented from being generated and high-quality printing can be easily performed.

  The printing position adjusting means is a relative position between a plate making position to the first master wound around the first plate cylinder and a plate making position to the second master wound around the second plate cylinder. If the printing speed is adjusted, the change in the relative position between the first printing position and the second printing position caused by the change in the driving load applied to the driving force transmitting means when the printing speed is adjusted is applied to each plate cylinder. By offsetting by adjusting the plate-making position on the master to be wound, there is no deviation of the printing position before and after adjusting the printing speed, and ghost images are prevented from occurring and high-quality printing is easily performed. A printing apparatus that can be provided can be provided.

  FIG. 1 shows an outline of a thermosensitive digital plate-making integrated stencil printing apparatus which is a multicolor stencil printing apparatus as a printing apparatus capable of forming a monochrome image or a color image to which the present invention is applied. The stencil printing apparatus 100 includes a plurality of plate cylinders for printing with inks of different colors, specifically, a first printing drum 1A as a first plate cylinder and a second plate cylinder as a first plate cylinder. It has a second printing drum 1B (hereinafter referred to as “printing drum 1A” and “printing drum 1B”, respectively). The printing drum 1A is upstream of the paper conveyance direction indicated by arrow Z (hereinafter referred to as “paper conveyance direction Z”), and the printing drum 1B is downstream of the printing drum 1A in the paper conveyance direction Z, that is, left in FIG. Are arranged side by side and arranged side by side.

  In the present embodiment, constituent members corresponding to the printing drum 1A are denoted by reference numeral A at the end of the numerical symbol, and constituent members corresponding to the printing drum 1B are denoted by reference character B at the end of the numerical symbol. Moreover, the same numerical code | symbol is attached | subjected to the structural member which has the same function and structure, and duplication description is abbreviate | omitted as much as possible.

  The stencil printing apparatus 100 includes press rollers 2A and 2B, which are pressing means as printing pressure members, a first plate making means, and a second plate making, respectively, around the printing drum 1A and the printing drum 1B in the apparatus main body. Plate making and feeding apparatuses 3A and 3B as means, plate discharging apparatuses 88A and 88B shown in FIG. 3 for separating and discarding used masters from the printing drum 1A and printing drum 1B, and press rollers 2A and 2B are connected to the printing drums 1A and 1B. From holding means 5A and 5B as locking means for holding at positions separated from the respective outer peripheral surfaces (hereinafter referred to as “drum outer peripheral surface 1Aa” and “drum outer peripheral surface 1Ba”), the printing drum 1A, and the printing drum 1B A separation claw 7A as a first separation claw, a separation claw 7B as a second separation claw, and an airflow generating means 120A as a first separation fan for separating the printed paper 35. And a stream generation unit 120B as the second release fan.

  The stencil printing apparatus 100 is also disposed between the printing drum 1A and the printing drum 1B, and a sheet feeding device 4 serving as a sheet feeding means for loading the sheets 35 and supplying them to the printing drums 1A and 1B. As shown in FIG. 3, a transport device 21 serving as transport means for transporting 35 from the print drum 1A to the print drum 1B, a paper discharge tray 45 for stacking printed paper 35, and an upper portion of the apparatus main body are shown. It has an operation panel 51 and control means 90, and a document reading device (not shown) as a scanner unit.

  The printing drum 1A and the printing drum 1B are located below the plate making and feeding apparatuses 3A and 3B and the plate discharging apparatus. The printing drum 1A and the printing drum 1B include a plurality of porous support cylinders 1a and 1b having openings 1a1 and 1b1 and non-openings 1a2 and 1b2, and a plurality of unillustrated covers covering the outer peripheries of the porous support cylinders 1a and 1b. It is a well-known porous cylindrical structure having a mesh screen of layers. The mesh screen is made of a resin or a metal net.

  The printing drum 1A and the printing drum 1B are also formed of a magnetic material along one bus bar of the printing drums 1A and 1B on portions of the drum outer peripheral surfaces 1Aa and 1Ba corresponding to the non-opening portions 1a2 and 1b2. The first stage 41A and the second stage 41B, and the first clamper 42A and the second clamper 42B that are rotatably supported so as to be openable and closable with respect to each of the first stage 41A and the second stage 41B are provided. is doing.

  The first clamper 42A and the second clamper 42B are opened and closed at predetermined positions by an opening / closing device (not shown). The printing drum 1A and the printing drum 1B are rotatably supported by a drum shaft 25A as a first ink pipe and a drum shaft 25B as a second ink pipe via drum flanges 20A and 20B. Both ends of the drum shafts 25A and 25B are fixed to a pair of side plates (not shown) that are detachably attached to the apparatus main body. The printing drum 1A and the printing drum 1B are rotationally driven by a main body motor 81 as driving means shown in FIG. 2 so that the rotation speed V1 of the drum outer peripheral surfaces 1Aa and 1Ba is 1000 mm / s in the direction of the arrow shown in FIG. It has come to be.

  As shown in FIG. 1, inside the printing drums 1A and 1B, an ink roller 60A as a first ink roller, an ink roller 60B as a second ink roller, and an ink roller 60A constituting the ink reservoirs 62A and 62B, respectively. , 60B, a doctor roller 61A as a first doctor roller, and a doctor roller 61B as a second doctor roller, which are disposed with a slight gap, are respectively disposed. The ink reservoirs 62A and 62B are respectively formed in a wedge-shaped space formed by the ink roller 60A and the doctor roller 61A, and a wedge-shaped space formed by the ink roller 60B and the doctor roller 61B.

  The ink rollers 60A and 60B are rotatably supported at their shaft portions by side plate pairs to which the drum shafts 25A and 25B are fixed, respectively, and drive transmission means (not shown) having gears and belts (not shown), respectively. The main body motor 81 is driven to rotate in the direction of the arrow in synchronization with the printing drums 1A and 1B. The ink rollers 60A and 60B rotate to knead and extend the ink in the ink reservoirs 62A and 62B, and the ink in the ink reservoirs 62A and 62B is supplied to the drum inner peripheral surface through the outer surfaces of the ink rollers 60A and 60B. It has become so.

  Each of the drum shafts 25A and 25B has a function of an ink supply pipe. The drum shafts 25A and 25B are formed with a plurality of holes as supply holes (not shown) in the axial direction. One end of each of the drum shafts 25A and 25B is connected via an ink pump (not shown) to an ink pack (not shown) provided outside the printing drum 1A and the printing drum 1B in which different colors of ink are stored. Yes.

When it is detected that the amount of ink in the ink reservoirs 62A and 62B has been reduced by an ink sensor (not shown), the ink in the ink pack is sucked by the ink pump and from the plurality of holes formed in the drum shafts 25A and 25B. The ink is supplied to the ink reservoirs 62A and 62B. Black ink is supplied to the ink reservoir 62A, and red ink is supplied to the ink reservoir 62B.
The printing drum 1A and the printing drum 1B are detachable from the apparatus main body as a unit integrally with an ink supply unit including ink rollers 60A and 60B and doctor rollers 61A and 61B, respectively.

  Each of the plate-making and feeding apparatuses 3A and 3B includes master rolls 32A and 32B each having a master 31A as a first master and a master 31B as a second master wound in a roll shape, and the masters 31A and 31B are punched by heat. The thermal head 33A as the first perforation member to be performed, the thermal head 33B as the second perforation member, the platen rollers 34A and 34B disposed facing the thermal heads 33A and 33B, and the master on which the perforation has been performed Cutting means 35A, 35B for cutting 31A, 31B, master transport roller pair 36A, 36B for transporting perforated master 31A, 31B, and master 31A, 31B transported by master transport roller pair 36A, 36B Guide plates 37A and 37B for guiding to the printing drums 1A and 1B are provided.

  The platen rollers 34A and 34B have an axial length substantially the same as the width of the masters 31A and 31B, and are rotatably supported between side plates (not shown) of the apparatus main body. The platen rollers 34A and 34B receive driving force from a stepping motor (not shown) and are driven to rotate in the clockwise direction in FIG.

  The thermal heads 33A and 33B are formed so that the width thereof is larger than the axial length of the platen rollers 34A and 34B, and a plurality of heating elements are disposed on the upper surfaces thereof. The thermal heads 33A and 33B are urged by urging means (not shown) so that their heating element surfaces are pressed against the platen rollers 34A and 34B, and the operation of each heating element is individually controlled by a thermal head driver (not shown). The

  The cutting means 35A and 35B are fixed to the apparatus main body (not shown), and the width of the lower blades 35Aa and 35Ba formed longer than the width of the masters 31A and 31B, and the width direction of the masters 31A and 31B on the lower blades 35Aa and 35Ba. This is a well-known configuration having upper blades 35Ab and 35Bb provided so as to be rotatable while moving.

  A pair of master transport rollers 36A and 36B includes a drive roller 36Aa and 36Ba that is rotatably supported between side plates (not shown) and is driven to rotate by a master transport drive unit (not shown), and a driven roller that is in pressure contact with the drive rollers 36Aa and 36Ba. 36Ab and 36Bb, and the masters 31A and 31B are sandwiched and conveyed by the driving rollers 36Aa and 36Ba and the driven rollers 36Ab and 36Bb.

  The guide plates 37A and 37B are fixed between side plates (not shown). The masters 31A and 31B are stencil masters having a laminate structure in which a thermoplastic resin film and a porous support are bonded together. As the thermoplastic resin film, a film having a thickness of about 1 to 3 μm is used. As the porous support, Japanese paper fiber, synthetic fiber, or a mixture of Japanese paper and synthetic fiber is used.

  The holding means 5A, 5B include arm members 40A as first press roller arms, arm members 40B as second press roller arms, and arm members 40B as second press roller arms that support the press rollers 2A, 2B so as to be able to come into contact with and separate from the drum outer peripheral surfaces 1Aa, 1Ba. The shafts 44A and 44B that support the members 40A and 40B are slidably supported, and only these are shown in FIG. 1, but they are also provided so as to be detachable from the support arm members 40A and 40B. As a stopper driving source for moving the stopper toward the disengagement position from the arm members 40A and 40B, the tension spring as an urging means for urging each stopper in the locking direction with the arm members 40A and 40B. An electromagnetic solenoid is provided.

  The arm members 40A and 40B are partially omitted in illustration, but are substantially L-shaped, and the bent portions thereof are supported by the shafts 44A and 44B so as to be swingable. The shafts 44A and 44B are rotatably supported by a main body frame as a casing (not shown). The press rollers 2A and 2B are rotatably supported at one ends of the arm members 40A and 40B, respectively.

  The press rollers 2A and 2B have a cored bar and nitrile rubber or chloroprene rubber as an elastic body formed in a cylindrical shape and mounted around the cored bar. On the other end side of the arm members 40A and 40B, one end of a press roller tension which gives the arm members 40A and 40B a turning behavior in the clockwise direction and also gives a printing pressure to the printing drums 1A and 1B. It is locked. The other end of the press roller tension is locked to the main body frame (not shown).

  A roller (not shown) is disposed on the other end of each of the arm members 40A and 40B. This roller is in pressure contact with the contour peripheral surface of a cam (not shown) that brings the outer peripheral surfaces of the press rollers 2A and 2B into contact with and away from the drum outer peripheral surfaces 1Aa and 1Ba, respectively. This cam is configured to rotate in synchronization with the rotation of the printing drum 1A and the printing drum 1B via a coupling mechanism (not shown).

  By these members, the press rollers 2A and 2B can move between a separated position away from the drum outer peripheral surfaces 1Aa and 1Ba and a pressing position where the press rollers 2A and 2Ba are pressed against the drum outer peripheral surfaces 1Aa and 1Ba. That is, the press rollers 2A and 2B can contact and separate from the printing drum 1A and the printing drum 1B. Also, with these members, the press rollers 2A and 2B pass through the printing portions 18A and 18B, which are areas where the first clamper 42A and the second clamper 42B are opposed to the press rollers 2A and 2B and the drum outer peripheral surfaces 1Aa and 1Ba. In this case, the drum outer peripheral surfaces 1Aa and 1Ba are separated from each other.

  The press rollers 2A and 2B continuously press the fed paper 35 against the drum outer peripheral surfaces 1Aa and 1Ba from the front edge portions of the openings 1a1 and 1b2, and transfer the ink image onto the paper 35 for printing. It has a function to perform. When the ink images are transferred onto the paper 35, the press rollers 2A and 2B contact the printing drums 1A and 1B slightly from the front edge of the openings 1a1 and 1b1 forming portions in the rotation direction of the printing drums 1A and 1B. It comes close to the printing drums 1A and 1B so as to come into contact.

  The separation claws 7A and 7B and the airflow generation means 120A and 120B are arranged on the left side of the printing drums 1A and 1B in FIG. 1, and are for separating and peeling the paper 35 from the drum outer peripheral surfaces 1Aa and 1Ba, respectively. It is. The separation claws 7A and 7B are arranged so as to approach the drum outer peripheral surfaces 1Aa and 1Ba from the downstream side of the printing portions 18A and 18B in the rotation direction of the printing drums 1A and 1B, respectively. The airflow generation means 120A and 120B include fan drive motors 66A and 66B serving as an airflow generation source, and ejection units 6A and 6B that blow the airflow generated by the fan drive motors 66A and 66B toward the printing units 18A and 18B. Yes. A plurality of separation claws 7A and 7B are arranged in a comb shape in the width direction of the paper 35 so that the airflow supplied from the ejection portions 6A and 6B can be passed near the printing portions 18 and 19. It is configured.

  The paper feeding device 4 is disposed on the right side of the apparatus main body, in other words, on the right side of the printing drum 1A. The sheet feeding device 4 includes a sheet feeding tray 10 on which a sheet 35 can be stacked, a sheet feeding tray 10 that can be moved up and down, a sheet feeding roller 11 that feeds from the top of the sheets 35 loaded on the sheet feeding tray 10, and a sheet feeding roller. 11, a separation roller 12 as a separation roller and a separation plate 14 as a separation member, and a single sheet 35 fed by the separation roller 12 and the separation plate 14. , A registration roller pair 17 that is sent to the printing unit 18A at a predetermined timing, and a sheet length detection unit that is disposed in the sheet feeding tray 10 and detects the length of the sheet 35 stacked on the sheet feeding tray 10. And a plurality of sensors 15. A detection signal from the sensor 15 is sent to the control means 90.

  The calling roller 11 and the separation roller 12 are rotated by appropriately controlling the driving of the driving unit described later by the control means 90 at the time of printing, printing, and trial printing, and after the masters 31A and 31B are wound. One sheet 35 is fed at the time of printing, and the sheet 35 is fed until printing for the set number of sheets is completed at the time of printing or trial printing.

  The registration roller pair 17 includes a driving roller 17a and a driven roller 17b that is in pressure contact with the driving roller 17a. The driving roller 17a is rotationally driven by a stepping motor (not shown). The driving roller 17a and the driven roller 17b are rotatably supported on a side plate (not shown). The registration roller pair 17 can adjust the feeding timing of the paper 35 by changing the driving timing of the stepping motor. The feeding of the paper 35 from the registration roller pair 17 is detected by a paper insertion sensor (not shown).

The transport device 21 constitutes a paper transport path between the printing drum 1A and the printing drum 1B. The conveying device 21 is wound around a driving roller 26 as a right conveying roller and a driven roller 27 as a left conveying roller, and a driving roller 26 and a driven roller 27 that are rotatably supported by a casing side plate (not shown). In addition, a transport belt 28 having a large number of openings and a suction fan 29 disposed inside the transport belt 28 are provided.
A suction force generated by the rotation of the suction fan 29 acts on the transport surface of the transport belt 28. The number of rotations of the suction fan 29 is controlled by the control means 90 changing the current, voltage, energization waveform, and the like.

  Since the transport device 21 has such a configuration, the paper 35 that has passed through the printing unit 18A and has been separated and peeled from the drum outer peripheral surfaces 1Aa and 1Ba by the separation claws 7A and 7B and the airflow generation means 120A and 120B is transported by the transport belt 28. It is configured to be attracted upward and conveyed toward the downstream side in the sheet conveyance direction Z, that is, toward the printing unit 18B or the discharge tray 45.

  The paper discharge tray 45 is disposed on the downstream side of the printing unit 18B in the paper transport direction Z. The paper discharge tray 45 can stack a large number of printed sheets 35. Between the printing unit 18B and the paper discharge tray 45, a paper discharge check sensor (not shown) for detecting the passage of the printed paper 35 is disposed, and the printed paper 35 is discharged to the paper discharge tray 45. It comes to detect that.

  The operation panel 51 includes a plate making key (not shown) for starting a series of operations from reading an image of a document to plate making, plate feeding, and plate making, a test printing key (not shown) for starting trial printing, a numeric keypad 52, A printing key (not shown) for starting a printing operation for a set number of sheets input by the ten key 52, a single mode key (not shown) for setting a single printing mode using one printing drum, and a tandem printing mode using two printing drums A tandem mode key (not shown) for setting a print drum, a first drum selection key and a second drum selection key (not shown) used when a printing drum is arbitrarily selected, a speed adjustment key 53 for adjusting a printing speed, and an image position adjustment operation are started. Phase adjustment key 54 as an image position adjustment key for printing, the number of prints and the number of prints remaining, selected Display unit or the like (not shown) which is a liquid crystal display device (not shown) for displaying the printing drum information, printing mode, etc. are arranged.

  The document reading apparatus has an image sensor composed of photoelectric conversion elements such as ADF and CCD, an analog / digital conversion board, and the like, photoelectrically converts the read image by the image sensor, and the photoelectrically converted electric signal is not shown in the analog / digital signal. This is a well-known configuration for converting to a digital image signal by transmitting to a digital conversion board. The digital image signal generated by the document reading device is sent to the control unit 90.

  The lengths of the drum outer peripheral surfaces 1Aa and 1Ba are approximately 3/4 of the span between the separation and separation positions of the paper 35 from the drum outer peripheral surfaces 1Aa and 1Ba. Further, the conveyance speed of the paper 35 by the conveyance device 21 is substantially equal to the rotation speed V1 of the printing drum 1A. From such a relationship between the length and speed, the phase of the printing drum 1B is greater than the phase of the printing drum 1A so that the printing image by the printing drum 1A and the printing image by the printing drum 1B occupy the same position on the paper 35. The relationship is delayed by approximately 1/3, that is, shifted by approximately 120 ° later.

  The phase relationship between the printing drum 1A and the printing drum 1B, in other words, the positional relationship can be set by the top and bottom moving device 80 which is the top and bottom moving means shown in FIG. The top and bottom moving device 80 is of a belt type that connects the printing drum 1A and the printing drum 1B to each other.

  The top and bottom moving device 80 includes a main body motor 81, a pulley 82A serving as a first plate cylinder pulley and a pulley 82B serving as a second plate cylinder pulley that are provided in the printing drums 1A and 1B, respectively, and rotate integrally with the printing drums 1A and 1B. A slider 83 disposed between the printing drums 1A and 1B, movable pulleys 84 and 84 rotatably supported at both ends of the slider 83, and a toothed belt as an endless belt wound around the pulleys 82A and 82B. FIG. 3 shows a certain connecting belt 85, tension rollers 86 as a plurality of fixed pulleys positioned on both sides of the slider 83 and pressing the connecting belt 85, and the slider 83. And a vertical movement motor 87 shown in FIG.

  The main body motor 81 is connected to the pulley 82 </ b> A and is driven by the control means 90. Each tension roller 86 is rotatably supported by a main body frame (not shown). The slider 83 extends in the vertical direction indicated by arrows a and b in FIG. 2 (hereinafter referred to as “vertical direction a and b”), and is supported by a body frame (not shown) so as to be movable in the vertical directions a and b. Has been. The slider 83 is selectively displaced in the vertical directions a and b by the top and bottom moving motor 87. Since the printing drum 1 </ b> A is directly connected to the main body motor 81, the main body motor 81 becomes a load and becomes a fixed side during image adjustment in which the top and bottom movement motor 87 is driven.

  Since the top / bottom movement device 80 has such a configuration, the printing drum 1B rotates in the clockwise direction when the slider 83 moves in the direction of arrow a by driving the top / bottom movement motor 87, so that the printing position is in the paper transport direction Z. When the slider 83 moves in the direction of the arrow b, the print position is moved upstream in the paper transport direction Z. When the main body motor 81 is driven, the printing drums 1A and 1B are driven to rotate in the same direction, that is, in the clockwise direction.

  The rotation speed and direction of the printing drum 1A and the printing drum 1B are controlled by controlling the driving of the main body motor 81 by the control means 90. The rotation speed is controlled based on the operation of the speed adjustment key 53. The rotation speed is adjusted in accordance with, for example, a change in ambient temperature. In this embodiment, one of extremely low speed, low speed, medium speed, and high speed is selected by operating the speed adjustment key 53. It has become.

  Therefore, the moving pulleys 84, 84, the connecting belt 85, and the tension roller 86 transmit the driving force applied to the printing drum 1A by the main body motor 81 to the printing drum 1B to drive the driving drum 1B. It functions as a means. The driving unit 90 and the speed adjustment key 53 function as a driving speed adjusting unit that adjusts the driving speed of the printing drum 1A and the printing drum 1B.

  As shown in FIG. 3, the control means 90 includes a CPU 91, a ROM 92, a RAM 93, etc., and is mainly composed of a known microcomputer connected by a signal bus (not shown). The CPU 91 is connected to the main body motor 81, the top and bottom moving motor 87, the plate making and feeding apparatuses 3 </ b> A and 3 </ b> B, the plate discharging apparatuses 88 </ b> A and 88 </ b> B, the paper feeding apparatus 4, various keys and display units of the operation panel 51, and the original reading Devices and the like are electrically connected to each other. The ROM 92 stores a table and the like which will be described later.

  With respect to the sensor 15, the control unit 90 determines the size of the paper 35 according to the detection signal from the sensor 15, and also determines the presence or absence of the paper 35. Regarding the plate making and feeding apparatus 3A, 3B, the control means 90 performs drive control of the thermal heads 33A, 33B, the platen rollers 34A, 34B, the cutting means 35A, 35B, and the master transport roller pairs 36A, 36B. Is called. With respect to the sheet feeding device 4, the control unit 90 performs drive control of the calling roller 11, the separation roller 12, and the registration roller pair 17, control related to raising and lowering of the sheet feeding tray 10, and the like.

  Further, in the control means 90, drive control of the main body motor 81, controls in the plate discharge devices 88A and 88B, controls in the document reading device, output control to the display unit, drive control of the top and bottom moving motor 87 described later, and the like are performed. . These controls are performed by the CPU 91 while appropriately using the RAM 92 based on various data recorded in the ROM 93 and based on input from the operation panel.

  Here, when the speed adjustment key 53 is pressed and the control unit 90 changes the rotation speed of the main body motor 81 to change the printing speed, there is a problem that a printing position shift occurs in the paper transport direction Z. That is, when the printing speed is changed, as shown in FIG. 4A, the print image 55A by the print drum 1A and the print image 55B by the print drum 1B have been formed at appropriate positions on the paper 35 until then. Regardless of this, the load applied to the connecting belt 85 and the like fluctuates due to the change in the printing speed, the connecting belt 85 bends and extends, and other moving pulleys 82A, 82B and 84, the tension roller 86, other members such as shafts, etc. When the phase of the printing drum 1B is changed due to the deformation or the like, and this change occurs on the delay side, as a result, as shown in FIG. 4B, the printing position of the printing image 55B is changed to the printing image. There is a problem that the printing position of 55A is shifted to the upstream side in the paper transport direction Z.

  In addition, when such a shift occurs, there arises a problem that a ghost image is generated. That is, when printing is repeatedly performed on the printing drums 1A and 1B, the ink printed on the paper 35 by the upstream printing drum 1A in the paper transport direction Z is transferred onto the downstream printing drum 1B in the paper transport direction Z. It is transferred to and stored in the wound master 31B. If the phases of the printing drums 1A and 1B do not fluctuate, even if the ink transferred to the master 31B adheres to the paper 35 again, only the image shown in FIG. 4A is formed and no ghost image is generated. However, when the relative printing positions of the printing drums 1A and 1B are shifted due to the above-described causes and the ink transferred to the master 31B adheres to the paper 35 again, the printed image 55A of the printing drum 1A is shifted from the original printing position. As shown in FIG. 4B, a ghost image 55A ′ is generated.

  Such a problem can be solved by moving to a mode for adjusting the print position when adjusting the printing speed and performing a test print while adjusting the print speed. Problems such as troublesome work, time-consuming work, and wasted paper for trial printing.

  Therefore, in the stencil printing apparatus 100 of the present embodiment, when the printing speed is adjusted, the control unit 90 uses the top and bottom moving device 80 to connect the printing drum 1A to the printing speed before adjustment and the printing speed after adjustment. By shifting the relative phase with the printing drum 1B, the printing images 55A and 55B are printed at the original printing positions.

  Specifically, the control means 90 reads the displacement amount of the slider 83 recorded in the ROM 93 by a table corresponding to the printing speed before adjustment and the printing speed after adjustment, and drives the top and bottom movement motor 87 based on this. . As a result, the relative position between the printing drum 1A and the printing drum 1B is adjusted based on the phase of the printing drum 1A, and the printing position of the printing drum 1A with respect to the paper 35 and the printing position of the printing drum 1B with respect to the paper 35 are adjusted. The relative positions are adjusted, and the print images 55A and 55B are printed at the original print positions before and after the change in the print speed, as shown in FIG.

  For example, referring to the example shown in FIG. 4, when adjustment is made in the direction of increasing the printing speed, the load applied to the connecting belt 85 and the like increases, and the phase of the printing drum 1 </ b> B is delayed due to the extension of the connecting belt 85. Change to the side. In this case, if this is left unattended, as a result, as shown in FIG. 4B, the print position of the print image 55B may be shifted upstream in the paper transport direction Z, and a ghost image 55A 'may be generated. Therefore, the control means 90 reads the displacement amount of the slider 83 recorded in the ROM 93 determined from the speed before and after the change, displaces the slider 83 upward by a predetermined amount, and rotationally drives the printing drum 1B in the clockwise direction. The phase is advanced so that the print position of the print image 55B matches the print position of the print image 55A.

  The amount of displacement of the slider 83 is, for example, about 0.3 mm when shifting from a very low speed to a low speed, about 0.5 mm when shifting from a low speed to a medium speed, and about 0.7 mm when shifting from a medium speed to a high speed. The print position of the print image 55B is determined so as to be shifted upstream in the paper transport direction Z, and these are recorded in the table of the ROM 93.

  The top and bottom moving motor 87, the slider 83, and the control unit 90 function as a phase adjusting unit that adjusts the phase between the printing drum 1A and the printing drum 1B, thereby printing the print position of the print image 55A and the print image 55B. It functions as a printing position adjusting means for adjusting the relative position to the position. Further, the slider 83 is displaced by the control means 90 to change the engagement position between the connecting belt 85 and the printing drum 1B, and as a phase adjusting member that adjusts the phase between the printing drum 1A and the printing drum 1B. Function. The control unit 90 adjusts the relative position by the print position adjusting unit, and relatively matches the print position.

  Since the stencil printing apparatus 100 has the above-described configuration, when the operator sets a document on the document reading apparatus, performs predetermined settings on the operation panel 51, and presses the plate-making key, the controller 90 discharges the plate. Accordingly, the printing drums 1A and 1B are rotated, and are discharged by the plate discharging devices 88A and 88B. When this is completed, the plate making and plate feeding devices 3A and 3B perform plate making and plate feeding. The edition is complete.

  Subsequently, the control unit 90 drives the paper feeding device 4 to start feeding, and when the paper insertion sensor detects that the paper 35 has been sent out from the registration roller pair 17, the control means 90 leaves the drum outer peripheral surfaces 1Aa and 1Ba. The holding of the press rollers 2A and 2B at the separated position is released, and the press rollers 2A and 2B are moved to a pressing position where the press rollers 2A and 2B are pressed against the drum outer peripheral surfaces 1Aa and 1Ba in accordance with the passage timing of the paper 35. Print. When the passage of the printed paper 35 is detected by the paper discharge check sensor, the printing is completed. Thereafter, if necessary, the operator adjusts the printing position by the printing drums 1A and 1B with the position adjustment key 54, for example, to obtain an image as shown in FIG. A test print can be performed by pressing.

  When the operator inputs the number of prints with the numeric keypad 52 and presses the print key, the control unit 90 starts printing, counts the number of prints, repeats printing until the input number of prints is reached, and is input When printing of the number of sheets is completed, printing is stopped. When the printing speed is adjusted by the speed adjustment key 53 in the process of printing, trial printing, and printing, the phase of the printing drum 1B is adjusted as described above to prevent the occurrence of printing position shift and ghost image. And good printing is performed. At this time, the operation of the position adjustment key 54 is not necessary.

  As described above, the stencil printing apparatus 100 has been described as an embodiment for carrying out the present invention. However, the reference for the adjustment of the printing position is the plate cylinder on the upstream side in the paper conveyance direction like the stencil printing apparatus 100 described above. In this case, when an endless belt is used as the driving force transmitting means, the engagement position between the endless belt and the downstream plate cylinder is changed. Also, the printing positions of both plate cylinders may be adjusted. In this case, when an endless belt is used as the driving force transmission means, the engagement positions of the endless belt and the upstream and downstream plate cylinders are changed. It will be.

The printing position adjusting means does not adjust the phase of the plate cylinder, but may adjust the plate making position relative to the master wound around each plate cylinder. This can be realized by adjusting the relative operation timing between the heads 33A and 33B.
In the above-described embodiment, when the driving speed is high, the printing position is adjusted by shifting the second printing position to the downstream side in the paper conveyance direction as compared to when the driving speed is low. In addition, the printing position may be adjusted by shifting the first printing position to the upstream side in the paper transport direction.

  The driving unit may drive the plate cylinder on the downstream side in the paper conveyance direction, and the driving force transmission unit may transmit the driving force applied to the plate cylinder on the downstream side in the paper conveyance direction to the upstream plate cylinder. The driving force transmission means may be constituted by a gear without using an endless belt, or may be constituted by a combination of an endless belt and a gear.

  In the above-described embodiment, the paper is continuously pressed against each plate cylinder so as to print an image of two colors with one sheet passing. The printing may be stopped and printing may be performed only with the other plate cylinder to perform printing with only one color, and then printing with one plate cylinder may be started to perform two-color printing. At this time, if one of the plate cylinders is a downstream plate cylinder, a ghost image does not occur during printing with only one color even if ink is transferred to the downstream plate cylinder during position adjustment. When printing is performed using only one of the plate cylinders, the fan drive motor 66 provided for the plate cylinder can be inactivated.

  As described above, since the printing speed is adjusted according to the ambient temperature or the like, for example, a temperature detecting means such as a thermistor is provided in the stencil printing apparatus 100, and the control means 90 automatically operates according to the detected temperature. In this case, the print position can be adjusted as described above in accordance with the adjustment of the print speed. Further, if the control unit 90 is provided with a nonvolatile memory that stores the value adjusted by the operator using the position adjustment key 54 as a correction value for the displacement amount of the slider 83, the convenience is further improved and the printing position is more accurately detected. Deviations and ghost images can be prevented.

The present invention can be applied not only to stencil printing apparatuses but also to other types of printing apparatuses. The number of plate cylinders is not limited to two as in the stencil printing apparatus 100, and full color printing may be performed, for example, as four.
The application of the present invention is not limited to the above-described embodiment unless particularly limited in the above description.

1 is a front view showing an outline of a printing apparatus to which the present invention is applied. FIG. 2 is a front view illustrating a driving force transmission unit, a driving speed adjustment unit, a printing position adjustment unit, and a phase adjustment unit that are mounted on the printing apparatus illustrated in FIG. 1. FIG. 2 is a block diagram of a configuration of a control unit mounted on the printing apparatus illustrated in FIG. 1 and each unit connected thereto. It is a schematic diagram for demonstrating adjustment of the relative position of a 1st printing position and a 2nd printing position.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1A 1st printing cylinder 1B 2nd printing cylinder 31A 1st master 31B 2nd master 35 Paper 53, 90 Driving speed adjustment means 81 Driving means 83 Phase adjustment member 83, 87, 90 Printing position adjustment means, Phase adjustment Means 84, 85, 86 Driving force transmission means 85 Endless belt 90 Control means 100 Printing device Z Paper transport direction

Claims (4)

A first plate cylinder and a second plate cylinder;
Drive means for driving the first plate cylinder;
Driving force transmitting means for driving the second plate cylinder by transmitting the driving force applied to the first plate cylinder by the driving means;
Drive speed adjusting means for adjusting the drive speed of the first plate cylinder and the second plate cylinder;
A printing position adjusting means for adjusting a relative position between a first printing position, which is a printing position on the paper by the first plate cylinder, and a second printing position, which is a printing position on the paper by the second plate cylinder;
Have a control means for adjusting the relative position by the printing position adjusting means when the driving speed is adjusted by the driving speed adjusting means,
When the driving speed is high, the control means shifts the second printing position to the downstream side and / or shifts the first printing position to the upstream side in the paper transport direction compared to when the driving speed is low. A printing apparatus that adjusts the relative position .   2. The printing apparatus according to claim 1, wherein the printing position adjusting means includes phase adjusting means for adjusting a phase between the first plate cylinder and the second plate cylinder.   3. The printing apparatus according to claim 2, wherein the driving force transmitting means includes an endless belt that engages with the first plate cylinder and the second plate cylinder and rotates integrally, and the phase adjusting means is the control means. And a phase adjusting member that adjusts the phase by changing the engagement position between the endless belt and the first plate cylinder and / or the second plate cylinder.   4. The printing apparatus according to claim 1, wherein the printing position adjusting unit winds the plate making position on the first master wound around the first plate cylinder and the second plate cylinder. A printing apparatus characterized by adjusting a relative position with a plate making position to a second master to be mounted.

Images