JP2008006658A - Perfect printing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make it possible to perform perfect printing by selecting a skip paper feeding mode and leaving an interval for the perfect printing for setting the number of times of skip paper feeding during the perfect printing for the purpose of drying and fixing of printed images of a perfect printed article in a perfect printing apparatus performing the perfect printing through turning reversely of a press roller, paper re-feeding or the like in a paper re-feeding means. <P>SOLUTION: A controlling means in the perfect printing apparatus controls respective driving means for a paper feeding part 4, a printing part 2, the paper re-feeding means 9, a paper discharging part 6 and a switching member 10 so that based on a signal related to setting the skip paper feeding mode from a selection setting key, a signal related to setting the number of times of the skip paper feeding from a ten key and an enter key, a drum rotating position signal from a home position sensor 134 and an encoder sensor being not shown in a figure, and a drum speed signal, the interval for the perfect printing corresponding to setting the number of times of skip paper feeding is placed, and respective driving means, and operations and timings of constitutional elements, members or the like are satisfied. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a duplex printing apparatus, and more particularly to a duplex printing apparatus including a stencil printing apparatus capable of printing on both sides of a sheet in one step.

As a simple printing method, a digital thermal type stencil printing apparatus is known. In this stencil printing apparatus, a thermal head in which a large number of fine heating elements are arranged in the main scanning direction is brought into contact with a thermal stencil master (hereinafter referred to as “master”), and each heating element is pulse-energized while performing main scanning. By conveying the master in the sub-scanning direction (master conveyance direction) orthogonal to the direction, the master is heated, melted and perforated according to image information, and the pre-made master is provided with a porous cylindrical plate cylinder on the outer periphery The plate cylinder is wound around the outer peripheral surface of the printing drum of the printing drum and then pressed on the outer peripheral surface of the printing drum by pressing means such as a press roller via a printing paper (hereinafter simply referred to as “paper”) as a printing medium. The ink supplied to the inner periphery of the cylinder is passed through the opening portion of the plate cylinder and the perforated portion of the master that has been made, and is transferred to the paper to obtain a printed image. Hereinafter, the printing drum is also simply referred to as “drum”.
In a conventional stencil printing machine that prints only on one side of a sheet of paper, an undried print image of printed paper (hereinafter also referred to as “printed matter”) that has been discharged and stacked on a paper discharge tray during printing. On top of this, when the next printed material is discharged / stacked, the undried ink of the printed material previously discharged / stacked on the paper discharge tray is transferred to the back side of the next printed material and becomes dirty. An operation program called “skip paper feed mode” is set in order to prevent “turn-off” and the like. That is, the skip paper feed mode is to temporarily stop paper feeding (passing) for the number of skip paper feed set times and to rotate the plate cylinder idly with the pressing means being separated from the plate cylinder. The operation is performed. By stopping the paper feed for the number of skip paper feeds, the printing interval is increased until the next printed material is ejected / stacked on the paper output tray. By providing the printing stop time, it is possible to secure the drying / fixing time of the printed matter that has been discharged to the paper discharge tray first, thereby preventing set-off.

  In stencil printing, in addition to the single-sided printing described above, in recent years, double-sided printing, in which printing is performed on both sides of paper, has been frequently performed for the purpose of reducing paper consumption and document storage space. ing. Accordingly, the applicant of the present application has proposed a novel double-sided printing apparatus in order to meet the demand for double-sided printing from users (see, for example, Patent Documents 1 and 2).

JP 2003-200355 A JP 2004-26373 A

In the double-sided printing apparatus described in Patent Documents 1 and 2, as described with reference to FIGS. 1 to 6 and the like, the backside plate-making image is printed after the front side plate-making image (65A) is printed on the front surface during the double-sided printing operation. (65B) is printed on the back surface, but the front surface printing and the back surface printing are not performed on the same paper during one rotation of the plate cylinder, but are shifted by one rotation. That is, only the surface printing of the first sheet is performed at the first rotation of the plate cylinder, the surface printing on the second sheet is performed at the second rotation of the next plate cylinder, and the refeeding means (9). The reverse side printing on the first sheet reversely fed again by the rotation / reversal action of the press roller (13) is performed simultaneously and continuously, and the front side printing and the back side printing are performed during one rotation of the plate cylinder. Is not done on the same paper.
In the double-sided printing apparatus configured as described above, setting of the skip sheet feeding mode and control thereof are not taken into consideration.

Accordingly, the present invention has been made in view of the above-described circumstances, and skip feeding is performed during double-sided printing for the purpose of drying and fixing a printed image of double-sided printed paper (hereinafter also referred to as “double-sided printed material”). A first problem is to provide a double-sided printing apparatus that can select a mode and perform double-sided printing with a double-sided printing interval corresponding to the skip paper feed number setting.
A double-sided printing device that can perform double-sided printing with a double-sided printing interval set for each of the front-side and back-sided printing, with separate skip paper feed settings for double-sided printing for the same purpose as above It is a second problem to provide the above.
In addition, another object of the present invention is to provide a double-sided printing apparatus that can exhibit the effects and advantages described below.

In order to solve the above-described problems and achieve the above-mentioned object, the invention according to each claim employs the following characteristic means / invention-specific matters (hereinafter referred to as “configuration”).
The invention described in claim 1 is the plate cylinder on which the divided plate-making master formed by arranging two first plate-making images and two second plate-making images side by side along the rotation direction of the plate cylinder, and the plate A printing unit having a pressing unit that can be moved toward and away from the cylinder; a paper feeding unit that feeds the paper toward the printing unit; and a paper discharge that discharges the printed paper printed by the printing unit. And a surface-printed paper having a printed image formed on the surface thereof corresponding to the first plate-making image or the second plate-making image by the printing means, and thereafter the surface-printed paper is Refeeding means that feeds out toward the pressing means, reverses by the pressing means and refeeds toward the printing means, and paper that has passed through the printing means to the refeeding means or the paper discharge means Switching means for guiding, and at the time of duplex printing, the paper feeding means The first sheet is fed to the printing means, and surface printing corresponding to either the first plate-making image or the second plate-making image is performed on the surface, and the printed first sheet has been printed. After the paper is guided to the re-feeding means by the switching means, the second paper is fed from the paper feeding means to the printing means, and the first plate-making image and the second plate-making image are formed on the surface thereof. Surface printing corresponding to either one is performed, and the first sheet printed on the first sheet is re-fed to the printing unit by the re-feeding unit, and the first plate-making image and the second plate-making image are printed on the back side. Double-sided printing that performs backside printing corresponding to one of the other and guides the first double-side printed paper to the paper discharge unit and the second front-side printed paper to the refeed unit by the switching unit In the apparatus, when using double-sided printing, And a skip paper feed mode setting means for setting a skip paper feed mode for idly rotating the plate cylinder, and a skip for setting the number of skip paper feeds when the skip paper feed mode is set. Based on signals from the paper feed frequency setting means, the skip paper feed mode setting means, and the skip paper feed frequency setting means, the paper feed is set so as to leave a duplex printing interval corresponding to the skip paper feed frequency setting. And a control means for controlling each drive means of the printing means, the paper discharge means, the refeed means, and the switching means.

  According to a second aspect of the present invention, there is provided the plate cylinder on which the divided plate-making master, in which the first plate-making image and the second plate-making image are formed side by side along the rotation direction of the plate cylinder, is wound, and the plate. A printing unit having a pressing unit that can be moved toward and away from the cylinder; a paper feeding unit that feeds the paper toward the printing unit; and a paper discharge that discharges the printed paper printed by the printing unit. And a surface-printed paper having a printed image formed on the surface thereof corresponding to the first plate-making image or the second plate-making image by the printing means, and thereafter the surface-printed paper is Refeeding means that feeds out toward the pressing means, reverses by the pressing means and refeeds toward the printing means, and paper that has passed through the printing means to the refeeding means or the paper discharge means Switching means for guiding, and at the time of duplex printing, the paper feeding means The first sheet is fed to the printing means, and surface printing corresponding to either the first plate-making image or the second plate-making image is performed on the surface, and the printed first sheet has been printed. After the paper is guided to the re-feeding means by the switching means, the second paper is fed from the paper feeding means to the printing means, and the first plate-making image and the second plate-making image are formed on the surface thereof. Surface printing corresponding to either one is performed, and the first sheet printed on the first sheet is re-fed to the printing unit by the re-feeding unit, and the first plate-making image and the second plate-making image are printed on the back side. Double-sided printing that performs backside printing corresponding to one of the other and guides the first double-side printed paper to the paper discharge unit and the second front-side printed paper to the refeed unit by the switching unit In the apparatus, when using double-sided printing, And a skip sheet feeding mode setting means for setting a skip sheet feeding mode for idly rotating the plate cylinder, and a surface skip corresponding to the front surface printing at the time of setting the skip sheet feeding mode. A front-side skip feed number setting means for setting the number of feed times, a reverse-side skip feed number setting means for setting the reverse-side skip feed number corresponding to the reverse side printing when the skip feed mode is set, and the skip feed Based on signals from the paper mode setting means and the front-side skip feed number setting means or the skip-feed mode setting means and the back-side skip feed number setting means, the front-side skip feed number setting amount or the back-side skip feed number is set. The paper feeding means, the printing means, the paper discharging means, and the refeeding means so as to leave a double-sided printing interval corresponding to the set number of papers. And control means for controlling each driving means of the switching means.

  According to a third aspect of the present invention, there is provided the double-sided printing apparatus according to the second aspect, wherein the two-sided printing apparatus is configured to perform various types of duplexing set by the skip sheet feeding number setting unit, the front surface skip sheet feeding number setting unit, or the rear surface skip sheet feeding number setting unit. The control unit includes a selection unit that selects any one of the skip paper feed printing modes, and the control unit executes the double-side skip paper feed printing mode selected by the selection unit based on a signal from the selection unit. As described above, the drive means of the paper feed means, the printing means, the paper discharge means, the refeed means, and the switching means are controlled.

  According to a fourth aspect of the present invention, in the double-sided printing apparatus according to the third aspect, the various double-sided skip paper feed printing modes are preset as an initial state of the double-sided printing apparatus, and the various double-sided skip paper feed printing is performed. A change unit that changes the mode to a double-side skip paper feed print mode that is always used, and the control unit changes the double-side skip paper feed print mode changed by the change unit based on a signal from the change unit Each of the drive means of the paper feed means, the printing means, the paper discharge means, the refeed means and the switching means is controlled so as to execute.

According to this invention, the said subject can be solved and a novel double-sided printing apparatus can be provided. The effects of the invention for each claim are as follows.
According to the first aspect of the present invention, in the double-sided printing for the purpose of drying / fixing the double-sided printed material, the skip paper feeding mode is selected and the double-sided printing is performed with the printing interval set for the skip paper feeding number. Can do.

  According to the second aspect of the present invention, when the skip sheet feeding mode is selected at the time of double-sided printing, the number of skip sheet feedings corresponding to the front side and the back side in double-sided printing is individually set according to the above configuration. can do.

According to the third aspect of the present invention, since the double-side skip paper feed printing mode selected by the selection unit is automatically executed by the above configuration, the user only needs to select the double-side skip paper feed printing mode. Can be printed on both sides.
According to the fourth aspect of the present invention, with the above configuration, the user can perform desired double-sided printing only by selecting the double-side skip paper feed printing mode that is always used by the changing unit.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention (hereinafter referred to as “embodiments”) including the best mode for carrying out the invention and examples will be described below with reference to the drawings. In each embodiment and the like, components (members and components) having the same function, shape, and the like will be omitted by giving the same reference numerals after being described once. When quoting and explaining constituent elements such as published patent gazettes, parentheses are given to the reference numerals including the background art described above to distinguish them from those of the embodiments and the like.

A double-sided printing apparatus 1 according to a first example to which the present invention is applied will be described with reference to FIGS. First, the overall configuration of the double-sided printing apparatus 1 will be described with reference to FIG. In FIG. 1, a duplex printing apparatus 1 includes a printing unit 2 as a printing unit, a plate making unit 3, a paper feeding unit 4 as a paper feeding unit, a plate discharging unit 5 as a plate discharging unit, a paper discharging unit 6 as a paper discharging unit, and an image. A refeeding means 9 having a reading unit 7, an auxiliary tray 8, a paper tray 40, and the like, a switching member 10 as a switching means, and the like are provided.
The components constituting each part and means of the double-sided printing apparatus 1 are different from those shown in FIGS. 1 to 9, 16 and 17 of Japanese Patent Application Laid-Open No. 2004-26373, for example. Other than the names of the drive mechanism and the multistage cam, etc., the others are almost the same as the constituent elements of the above publication. The present invention relates to the slow-up operation control of the printing speed at the start of double-sided printing. From this point of view, the description of the configuration of each of the above parts and means that are not related to the present invention is omitted as appropriate.

The printing unit 2 disposed almost at the center of the apparatus main body 11 includes a printing drum 12 (hereinafter, also simply referred to as “plate cylinder 12” or “drum”) having a plate cylinder at the outer peripheral portion, and a plate cylinder 12. And a press roller 13 as a pressing means that can be freely contacted and separated.
The plate cylinder 12 includes a pair of end plates (not shown) rotatably supported by a support shaft 14 that also serves as an ink supply pipe, a porous support plate (not shown) wound around the outer peripheral surface of each end plate, and not shown. It is mainly composed of a mesh screen (not shown) wound around the outer peripheral surface of the porous support plate, and is rotationally driven by a main motor (not shown) constituting plate cylinder driving means 121 (see FIG. 9). In addition, it is configured to be detachable from the apparatus main body 11. In the first example, the plate cylinder 12 has a size capable of obtaining a maximum A3 size printed material during single-sided printing.

  The main motor (not shown) is composed of, for example, a DC motor, and is connected to the plate cylinder 12 via driving force transmission means such as gears and to the press roller 13 via driving force transmission means such as an endless belt and a pulley. The rotational speed of the plate cylinder 12, that is, the printing speed, is low as the main motor is controlled by the control means 129 shown in FIG. 9 through a motor drive circuit (not shown) as in the conventional apparatus. It is configured to be switched in 5 steps from 60 rpm to 15 rpm to 120 rpm.

An ink supply means 15 is disposed inside the plate cylinder 12. The ink supply means 15 includes a support shaft 14, an ink roller 16, a doctor roller 17, and the like.
The ink roller 16 is rotatably supported between side plates (not shown) provided in the plate cylinder 12, and the peripheral surface thereof is disposed close to the inner peripheral surface of the plate cylinder 12. It is rotationally driven in the same direction as the barrel 12. The doctor roller 17 is also rotatably supported between the side plates, and its peripheral surface is disposed close to the peripheral surface of the ink roller 16 and is driven to rotate in a direction opposite to the plate cylinder 12 by a driving means (not shown). . A plurality of small holes are formed in the support shaft 14, and the ink supplied from the support shaft 14 is collected in a wedge-shaped space formed in the vicinity of the ink roller 16 and the doctor roller 17. An ink reservoir 18 is formed.

  On the outer peripheral surface of the plate cylinder 12, a stage portion 19 a that forms a plane along one generatrix of the plate cylinder 12 is formed. On this, a clamper that holds the tip of the master on the outer peripheral surface of the plate cylinder 12. 19b is arranged to be openable and closable. The clamper 19b is opened and closed by an opening / closing means (not shown) provided on the apparatus main body 11 side when the plate cylinder 12 is rotated to a predetermined position.

A press roller 13 is disposed below the plate cylinder 12. The press roller 13 is formed by winding a metal core (shaft) 13 a with an oil-resistant elastic body, for example, nitrile rubber (NBR), in the axial direction of the support shaft 14 of the plate cylinder 12. It is extended and provided. As shown in FIG. 2, the press roller 13 is rotatably supported by a pair of arm members 20 at both ends of the core portion 13 a. Each arm member 20 having an approximately L-shape is integrated by a swing shaft 21 attached to a portion in the vicinity of the bent portion, and the swing shaft 21 is rotated within a predetermined angle range by the apparatus main body 11. It is supported so as to be movable, that is, swingable. In this example, the press roller 13 is constituted by a member having ink repellency such as polytetrafluoroethylene resin at least on the peripheral surface thereof.
The outer peripheral surface of the press roller 13 is uniformly coated or bonded with, for example, glass beads as vitreous fine particles, which are the same as those used for preventing smearing of printed matter, for example, in an offset printing machine, in addition to a member having ink repellency May be. Not only glassy fine particles but also ceramic fine particles may be used. As a result, when it comes into contact with the outer peripheral surface of the plate cylinder 12 or the divided plate-making master 65 or the plate-making master 66 on the plate cylinder 12, it comes into contact with the ink on the printed image surface side of the surface-printed paper as will be described later. Swelling and ink stains are minimized.

As described in part above, the press roller 13 is connected to the main motor via a driving force transmitting means such as a toothed endless belt and a pulley (not shown). It is rotationally driven at approximately the same peripheral speed. A toothed pulley (not shown) on the drive side that rotationally drives the press roller 13 is rotatably supported by the swing shaft 21. The rotational force from the plate cylinder 12 is the same as that of the plate cylinder driving means (80) shown in FIG. 2 of Japanese Patent Laid-Open No. 2001-191627 and driving force transmission means (not shown) such as a gear train or a pulley. (Combined with an endless belt) and transmitted to the drive pulley. The core portion 13a of the press roller 13 is provided with a toothed driven pulley that is rotatably provided so as to transmit a driving force only in a counterclockwise direction indicated by an arrow in the drawing via a one-way clutch (not shown). ing. A tensioned endless belt is stretched between the driving pulley and the driven pulley.
The drive mechanism of the press roller 13 is not limited to the above configuration, and may be driven and rotated by the same plate cylinder (12) as shown in FIG. 1 of Japanese Patent Application Laid-Open No. 2004-26373.

As shown in FIG. 2, between the arm members 20, in addition to the press roller 13, a refeed guide member 22, a refeed resist roller 23, a refeed positioning member 24, a refeed transport unit 25, a cleaning A roller 26, a guide plate 27, and the like are provided.
The refeed guide member 22 and the paper guide plate 31 are the same as those described in paragraphs “0026” to “0027” of Japanese Patent Application Laid-Open No. 2004-26373.

  Below the press roller 13, a refeed resist roller 23 is disposed as a refeed resist member. The roller-shaped refeeding registration roller 23 is rotatably supported by a support shaft 23 a, and the support shaft 23 a is attached to one end of a swing arm 32. The swing arm 32 is supported by a support shaft 32 a fixed between the arm members 20 so that the bent portion can swing freely. The repositioning registration roller 23 is arranged at the width of the press roller 13. It is determined so that it is located approximately in the center of the direction and is located in the middle of the position where each roller 30 is disposed.

  At the other end of the swing arm 32, a plunger 33a of a pull type solenoid 33 attached to one arm member 20 via a bracket (not shown) and one end are fixed to the one arm member 20 and attached to the swing arm 32. On the other hand, the other end of the tension spring 34 is attached, which applies a turning biasing force in the counterclockwise direction in FIG. With this configuration, when the solenoid 33 is turned on / operated (hereinafter simply referred to as “actuation or on”), the re-feeding registration roller 23 presses the peripheral surface thereof against the peripheral surface of the press roller 13 with a predetermined pressing force. 2 occupies the press contact position indicated by a solid line, and when the operation of the solenoid 33 is turned off / released (simply referred to as “release or off”), the peripheral surface is separated from the peripheral surface of the press roller 13 by the urging force of the tension spring 34. 2 occupies a separated position indicated by a two-dot chain line in FIG.

  A refeed conveyance unit 25 is disposed on the lower left side of the press roller 13. The refeed conveyance unit 25 includes a conveyance unit main body 35, a driving roller 36, a driven roller 37, an endless belt 38 as a sheet conveyance member, a suction fan 39, and the like. Have. The auxiliary tray 8 has a function as a refeed storage unit that temporarily stores the surface-printed paper printed by the printing unit 2.

  The transport unit main body 35, which is a housing whose upper surface is opened and whose width is slightly smaller than the interval between the arm members 20, is not shown on both side surfaces upstream and downstream in the paper transport direction. Each of the bearings (not shown) rotatably supports the drive shaft 36a and the driven shaft 37a. Both ends of the drive shaft 36 a penetrate both side surfaces of the transport member main body 35, and both the penetrated both ends are rotatably supported by bearing members (not shown) provided in the apparatus main body 11. A drive gear (not shown) is attached to one end of the drive shaft 36a, and the drive shaft 36a is rotationally driven by a transport unit drive motor 122 (see FIG. 9) provided in the apparatus main body 11. The driven shaft 37 a is configured such that both end portions thereof do not penetrate both side surfaces of the transport unit main body 35.

  Bosses 35a are integrally provided on both outer sides of the upstream end of the transport unit body 35 in the paper transport direction, and each boss 35a is inserted into a long hole (not shown) formed in each arm member 20, respectively. Loosely fitted. With this configuration, the transport unit main body 35 is centered on the drive shaft 36a along with the swing of each arm member 20 when the press roller 13 is brought into and out of contact with the plate cylinder 12 by a press roller contact / separation mechanism 55 described later. Can be swung.

  The plurality of roller-shaped drive rollers 36 are integrally attached to the drive shaft 36a, and a predetermined interval is provided between the drive rollers 36. A plurality of driven rollers 37 having the same shape as the driving roller 36 are integrally attached to the driven shaft 37 a at the same interval as each driving roller 36. An endless belt 38 is stretched between each driving roller 36 and each corresponding driven roller 37 corresponding thereto with a predetermined tension. The endless belt 38 made of a friction resistance member is moved in the direction indicated by the arrow in FIG. 2 when the drive shaft 36 a is rotationally driven by the transport unit drive motor 122.

  A suction fan 39 is integrally attached to the lower surface of the transport unit main body 35, and the auxiliary tray 8 is integrally attached to the upper surface of the transport unit main body 35. As shown in FIG. 3, the auxiliary tray 8 is configured such that a part of the circumferential surface of each of the rollers 36 and 37 faces the sheet conveying surface, and the auxiliary tray 8 is disposed on both sides of each endless belt 38 on the sheet conveying surface. A plurality of apertures 8b are formed, and two end fences 8a for receiving one end of the surface-printed paper PA sent from the printing unit 2 are integrally provided at the downstream end of the paper conveyance direction. It has been.

  At the upstream end of the auxiliary tray 8 in the paper conveyance direction, refeeding is performed to temporarily stop the other end of the front-side printed paper PA re-feeded to the printing unit 2 by the re-feed conveyance unit 25 at a fixed position. A paper positioning member 24 is provided. In this example, two re-feeding positioning members 24 are provided and are integrally attached to the auxiliary tray 8 respectively. Further, the auxiliary tray 8 is provided with a sensor 8c as a surface printed paper detection member that detects that the other end of the surface printed paper PA has approached the refeed positioning member 24. The sensor 8c outputs a signal to the control means 129 described later when the other end of the front surface printed paper PA is detected.

  A hole (not shown) is provided on the lower surface of the transport unit main body 35, which is a mounting surface of the suction fan 39, and the suction fan 39 is operated thereby to apply a negative pressure to the interior of the transport unit main body 35, which is a housing. The surface-printed paper PA is sucked onto the upper surface of each endless belt 38 that is generated and moved. The suction force of the suction fan 39 and the frictional resistance force of the endless belt 38 are determined between the surface-printed paper PA and each endless belt 38 when the other end of the surface-printed paper PA comes into contact with the refeed positioning member 24. Each is set to a strength that causes slippage between them.

  The auxiliary tray 8, the refeed guide member 22, the refeed registration roller 23, the refeed positioning member 24, and the refeed transport unit 25 constitute the refeed unit 9. The paper re-feeding means 9 has a paper tray 40 as a paper tray shown in FIGS. 1 and 3, and the paper tray 40 will be described later.

A cleaning roller 26 that cleans the peripheral surface of the press roller 13 is disposed in the vicinity of the press roller 13 and above the refeed conveyance unit 25. The cleaning roller 26 is the same as described in paragraphs “0038” to “0039” of Japanese Patent Application Laid-Open No. 2004-26373.
A guide plate 27 is disposed on the upper left side of the cleaning roller 26. Both ends of the guide plate 27 that is a plate material are fixed to the arm members 20, so that the surface-printed paper PA fed from the printing unit 2 does not touch the cleaning roller 26 and is directed to the auxiliary tray 8. To guide you. The guide plate 27 is disposed at a position close to each peripheral surface of the press roller 13 and the cleaning roller 26.

  On the other end side of each arm member 20 opposite to the one end side where the press roller 13 is supported, rotatable cam followers 41 are arranged so as to face each other. Further, the other end of the printing spring 42 having one end fixed to the apparatus main body 11 is attached in the vicinity of the position where the cam follower 41 of each arm member 20 is disposed. Thereby, each arm member 20 is given a rotation urging force in the clockwise direction in the drawing around the swing shaft 21.

  In the vicinity of the left side of each cam follower 41, a multistage cam 43 having three cam plates 43A, 43B, 43C is disposed. Each cam plate 43A, 43B, and 43C is fixed to a cam shaft 44 that is rotatably supported by the apparatus main body 11 at both ends and movably in the paper surface direction of FIG. The cam plate 43B, the cam plate 43A, and the cam plate 43C are arranged in this order. Each of the cam plates 43A, 43B, and 43C has a base portion that is a disc concentric with the cam shaft 44, and a convex portion (large diameter portion) having the same protruding amount. As shown in FIG. 4, the multistage cam 43 has plate cylinder driving means via a drive gear 45 attached to the camshaft 44 and a transmission gear 47 attached to a support shaft 46 rotatably supported by the apparatus body 11. The rotational force from 121 is transmitted, and it is rotated in the clockwise direction in FIG.

  The press roller 13 occupies a separation position shown in FIG. 2 in which the circumferential surface is separated from the circumferential surface of the plate cylinder 12 when any convex portion of each of the cam plates 43A, 43B, and 43C comes into contact with the cam follower 41. When the contact between any one of the convex portions and the cam follower 41 is released, the peripheral surface occupies the press contact position shown in FIG. 5 where the peripheral surface presses the peripheral surface of the plate cylinder 12 by the biasing force of the printing pressure spring 42. Each of the cam plates 43A, 43B, and 43C is configured so that the base and the cam follower 41 do not come into contact when the press roller 13 occupies the press contact position. The shape of the convex portions of the cam plates 43A, 43B, and 43C is such that the contact range between the press roller 13 and the plate cylinder 12 is a range in which all of the front surface region, the intermediate region, and the back surface region shown in FIG. Thus, the cam plate 43B is formed so as to be in the same range as the surface region, and the cam plate 43C is formed so as to be in the combined range of the downstream portion of the surface region, the intermediate region, and the back surface region. The intervals between the cam plates 43A, 43B, 43C are set to be sufficiently larger than the plate thickness of the arm member 20.

In FIG. 2, press roller locking means 180 that prohibits the swinging of each arm member 20 in a state where the press roller 13 occupies the separated position is disposed near the right side of each arm member 20.
One end of the press roller locking means 180 is fixed to a support shaft 182 that is supported by the apparatus main body 11 so as to be rotatable at a predetermined angle, and a pin is connected to the other end of the hook member 183 via a pin. A pull type printing pressure solenoid 181 having a connected plunger 181a, one end of which is locked to a hook member 183 between the support shaft 182 and the pin, and the other end locked to the apparatus main body 11 side. And a tension spring 184 as a biasing means. At the other end of the hook member 183, a hook portion 183a that selectively engages with a notch 20a formed at the other end of the arm member 20 is formed. The tension spring 184 swings and urges the hook portion 183a of the hook member 183 around the support shaft 182 in the clockwise direction, that is, always in the direction of engaging with the cutout portion 20a of the arm member 20.
The state of holding each arm member 20 and the state of releasing the holding are selectively switched by on / off switching control of the printing solenoid 181. As shown in FIG. 5, when the printing pressure solenoid 181 is energized and activated, the hook portion 183a swings counterclockwise and downward to disengage from the notched portion 20a of the arm member 20. Each arm member 20 swings clockwise and upward about the swing shaft 21, and a printing pressure is applied to the plate cylinder 12 via the press roller 13 by the urging force of each printing spring 42. The printing pressure solenoid 181 is operated in a state where the cam follower 41 is in contact with any one of the convex portions of the cam plates 43A, 43B, and 43C.

  As shown in FIG. 4, a moving arm 48 and a step cam 49 are disposed near the lower portion of the cam shaft 44. The moving arm 48 having a substantially L-shape has a bent portion attached to a support shaft 48a rotatably supported by the apparatus main body 11. A roller 48b is provided at one end of the moving arm 48, and the other end is provided at the other end. Each cam follower 48c is rotatably attached. Furthermore, the other end of the tension spring 50 having one end attached to the apparatus main body 11 is attached to a portion between the other end of the moving arm 48 and the bent portion, and the moving arm 48 is centered on the support shaft 48a. In the figure, a rotational biasing force in the clockwise direction is applied.

The roller 48 b is disposed between the discs 44 a and 44 b that are fixed to each other in the middle of the cam shaft 44, and the cam follower 48 c has its peripheral surface around the step cam 49 by the biasing force of the tension spring 50. It is in contact with the surface. The interval between the discs 44a and 44b is set to be slightly larger than the diameter of the roller 48b.
The step cam 49 has three cam portions 49 a, 49 b, and 49 c on its peripheral surface, and is fixed to a support shaft 51 that is rotatably supported by the apparatus body 11. A gear 54 that meshes with a gear 53 attached to an output shaft of a stepping motor 52 attached to the apparatus main body 11 is attached to the support shaft 51. It is rotationally driven in the direction. With this configuration, when the stepping motor 52 is actuated to rotate the step cam 49, the moving arm 48 swings about the support shaft 48a, and the roller 48b pushes the disk 44a or the disk 44b so that the camshaft 44 is illustrated. 4 in the left-right direction.

  Each cam portion 49a, 49b, 49c is in contact with the cam follower 48c and the cam portion 49b so that the cam plate 43B is in a position where the cam follower 41 can come into contact with the cam follower 41 when the cam follower 48c and the cam portion 49a contact each other. When the cam follower 48c and the cam portion 49c come into contact with each other so that the cam plate 43A comes into contact with the cam follower 41, the cam shaft 44C comes into contact with the cam follower 41. Each is formed in a shape to be moved.

  The above-described cam follower 41, the printing pressure spring 42, the multistage cam 43, the press roller locking means 180, the moving arm 48, the step cam 49, and the stepping motor 52 constitute a press roller contact / separation mechanism 55. By the operation of the mechanism 55, the press roller 13 selectively occupies the separated position shown in FIG. 2 and the press contact position shown in FIG. The printing pressure solenoid 181 of the press roller locking means 180 and the stepping motor 52 constitute a drive means for the press roller contact / separation mechanism 55.

  On the left side of the contact position (nip portion forming position) between the plate cylinder 12 and the press roller 13 and on the transport path of the paper P, a switching member 10 for switching the transport path of the paper P is disposed. The switching member 10 has a function as a switching unit that guides the paper that has passed through the printing unit 2 to the refeed unit 9 or the paper discharge unit 6. The switching member 10 made of a plate material having substantially the same width as the plate cylinder 12 and the press roller 13 is fixed to a support shaft supported at the apparatus main body 11 so as to be swingable at the downstream end in the sheet conveying direction, and is a solenoid. 123 (see FIG. 9) is activated, and the upstream end portion in the sheet conveying direction formed with an acute cross section is turned into a first displacement position indicated by a solid line and a second displacement position indicated by a two-dot chain line in FIG. Is selectively positioned.

  When the switching member 10 occupies the first displacement position, the tip of the switching member 10 is located close to the peripheral surface of the press roller 13 and does not interfere with the clamper 19b on the plate cylinder 12, and occupies the second displacement position. The tip of the plate cylinder 12 is placed close to the peripheral surface of the plate cylinder 12. The surface-printed paper PA that has passed between the plate cylinder 12 and the press roller 13 is guided to the paper discharge unit 6 when the switching member 10 occupies the first displacement position, and the switching member 10 is in the second position. When the displacement position is occupied, the guide plate 27 is guided to the auxiliary tray 8 through the space between the guide plate 27 and the guide plate 56 fixed to the apparatus main body 11.

  A plate making unit 3 is disposed in the upper right part of the apparatus main body 11. The plate making unit 3 includes a master holding member 57, a platen roller 58, a thermal head 59, a cutting means 60, a master stock unit 61, a tension roller pair 62, a reverse roller pair 63, and the like. The plate making unit 3 performs plate making on a master 64, which will be described later, and a divided plate making master 65 having a first plate making image 65A and a second plate making image 65B as shown in FIG. 6, or a first plate making as shown in FIG. A master-making master 66 having a third plate-making image 66A having an image amount area corresponding to two sides of the image 65A and the second plate-making image 65B is created. The first plate-making image 65A is formed at a position corresponding to the front surface area shown in FIG. 1 when the divided master-making master 65 is wound on the outer peripheral surface of the plate cylinder 12, and the second plate-making image 65B is a back surface area. It is formed at the corresponding position.

A master holding member 57, a platen roller 58, a thermal head 59 as a plate making means, a cutting blade 60a having a fixed blade 60a and a movable blade 60b movably supported by the fixed blade 60a, a master constituting the plate making unit 3. The detailed configuration contents of the stock unit 61, the tension roller pair 62 composed of the driving roller 62a and the driven roller 62b, the reversing roller pair 63 composed of the driving roller 63a and the driven roller 63b, and the like are disclosed in, for example, Japanese Patent Application Laid-Open No. 2004-26373. Since it is the same as that described in paragraphs “0052” to “0058”, description thereof is omitted.
Starting with a driving configuration including a stepping motor (not shown) that rotationally drives the platen roller 58, the tension roller pair 62, and the reversing roller pair 63, the driving configuration for driving the other components of the plate making unit 3 is generally made by plate making. Means 124 (see FIG. 9).

A sheet feeding unit 4 is disposed below the plate making unit 3. The sheet feeding unit 4 includes a sheet feeding table 67, a sheet size detection sensor 73 disposed on the sheet feeding table 67, a sheet feeding roller 68, a separation roller 69, a separation pad 70, a registration roller pair 71, and the like.
A paper feed table 67 on which a large number of sheets P can be stacked is supported by the apparatus main body 11 so as to be movable up and down, and is moved up and down by a paper feed driving means 125 (see FIG. 9) including an elevating means. A pair of side fences 72 supported by a rail member (not shown) so as to be movable in the paper width direction perpendicular to the paper transport direction are provided on the upper surface of the paper feed tray 67 on which A3 size paper P can be placed vertically. . A plurality of paper size detection sensors 73 that detect the size of the stacked paper P are provided on the free end side of the paper feed tray 67.

  Above the paper feed table 67, a paper feed roller 68 having a high frictional resistance member on the surface is disposed. The paper feed roller 68 is rotatably supported by a bracket (not shown) that is swingably supported by the apparatus main body 11. When the paper feed table 67 is lifted by a lifting means (not shown), paper is fed with a predetermined pressure contact force. The uppermost sheet P on the table 67 is pressed against. The paper feed roller 68 is rotationally driven by the paper feed driving means 125.

  On the left side of the paper feed roller 68, a separation roller 69 and a separation pad 70 each having a high friction resistance member on the surface are disposed. The separation roller 69 is drivingly connected to the paper feed roller 68 via a timing belt 69a, and is driven to rotate in the same direction in synchronization with the rotation of the paper feed roller 68. The separation pad 70 is pressed against the separation roller 69 by a biasing force of a biasing means (not shown).

A registration roller pair 71 is disposed on the left side of the separation roller 69 and the separation pad 70. The registration roller pair 71 including the driving roller 71a and the driven roller 71b transmits the rotational driving force from the plate cylinder driving unit 121 by a driving force transmitting unit (not shown) such as a gear or a cam, so that the driving roller 71a is connected to the plate cylinder. 12, the paper P is fed toward the printing unit 2 at a predetermined timing by a driven roller 71 b that rotates at a predetermined timing in synchronization with the driven roller 71 and is in pressure contact with the driving roller 71 a.
On the upstream side and the downstream side of the registration roller pair 71 in the sheet conveyance direction, sheet feeding guide plates 136 and 137 for guiding the conveyance of the sheet P fed from the sheet feeding unit 4 to the printing unit 2 are arranged, respectively. Has been. The paper feed guide plates 136 and 137 are respectively fixed between side plates (not shown) of the apparatus main body 11.

  At the upper left of the printing unit 2, a plate removal unit 5 is disposed. The plate discharging unit 5 includes an upper plate discharging member 74 including a driving roller 78, a driven roller 79, an endless belt 80, and the like, a lower plate discharging member 75 including a driving roller 81, a driven roller 82, an endless belt 83, and the like, and a plate discharging box 76. The compression plate 77 and the like have the same structure as those described in paragraphs “0064” to “0065” of Japanese Patent Application Laid-Open No. 2004-26373. Is omitted. The drive configuration for driving the components of the plate removal unit 5 is generally referred to as plate discharge drive means 126 (see FIG. 9).

A paper discharge unit 6 is disposed below the plate discharge unit 5. The paper discharge unit 6 includes a paper discharge conveyance unit 85 including a peeling claw 84, a driving roller 87, a driven roller 88, an endless belt 89, a suction fan 90, and the like, a paper discharge tray 86, and the like.
A plurality of peeling claws 84 are arranged in the width direction of the plate cylinder 12, and are respectively integrally attached to a support shaft that is swingably supported by the apparatus main body 11. The plurality of peeling claws 84 are swung by a claw rocking means (not shown), and the tips thereof are positioned close to the peripheral surface of the plate cylinder 12 and the tips of the claws 84 to avoid obstacles such as the clamper 19b. It selectively occupies a position away from the outer peripheral surface of the plate cylinder 12. The claw swinging means (not shown) transmits the driving force from the plate cylinder driving means 121 by the driving force transmission means (not shown), and swings the peeling claw 84 in synchronization with the rotation of the plate cylinder 12.

  A paper discharge conveyance unit 85 disposed below the peeling claw 84 and to the left of the switching member 10 includes a driving roller 87, a driven roller 88, an endless belt 89, a suction fan 90, and the like. A plurality of roller-like drive rollers 87 are attached to a support shaft (not shown) rotatably supported by a unit side plate (not shown) at a predetermined interval, and by a paper discharge driving means 127 (see FIG. 9) including a paper discharge motor and the like. Each is integrally rotated. A plurality of driven rollers 88 are also provided on a support shaft (not shown) rotatably supported on the same side plate at equal intervals with each drive roller 87, and an endless belt 89 is provided for each drive roller 87 and each corresponding driven roller 88 corresponding thereto. Each is over. A suction fan 90 is disposed below the driving roller 87, the driven roller 88, and the endless belt 89. The paper discharge transport unit 85 sucks the paper P onto each endless belt 89 by the suction force of the suction fan 90, and transports the printed paper PB in the direction of the arrow in FIG.

  A paper discharge tray 86 on which the printed paper PB conveyed by the paper discharge conveyance unit 85 is stacked is provided with one end fence 91 movable in the paper conveyance direction and a pair of side fences movable in the paper width direction. 92.

  An image reading unit 7 is disposed on the upper part of the apparatus main body 11. The image reading unit 7 includes a contact glass 93 on which a document is placed, a pressure plate 94 provided so as to be able to come in contact with and away from the contact glass 93, reflection mirrors 95, 96, 97, 98 for scanning and reading a document image, and a fluorescent lamp. 99, a lens 100 for focusing a scanned document image, an image sensor 101 such as a CCD for processing the focused image, a plurality of document size detection sensors 102 for detecting the size of the document, and an image for storing the read image data The document image reading operation is performed by the operation of the reading drive unit 128 (see FIG. 9).

  As shown in FIG. 1, a dog 133 is attached to the outer surface of an end plate (not shown) constituting the plate cylinder 12, and a home position sensor 134 attached to the apparatus main body 11 near the periphery of the plate cylinder 12. Is arranged. The home position sensor 134 detects the dog 133 when the plate cylinder 12 occupies a position where the clamper 19 b faces the press roller 13, and outputs a signal to the control means 129 described later.

FIG. 8 shows an operation panel of the duplex printing apparatus 1. In the figure, an operation panel 103 provided on the upper front surface of the apparatus main body 11 has a plate making start key 104, a printing start key 105, a test printing key 106, a continuous key 107, a clear / stop key 108, a numeric key 109, an enter on the upper surface. Key 110, program key 111, mode clear key 112, printing speed setting key 113, four-direction key 114, paper size setting key 115, paper thickness setting key 116, duplex printing key 117, simplex printing key 118, 7 segment LED A display device 119, a display device 120 including an LCD, and the like are included.
Detailed functions and configurations of these various keys and the display device 119 are the same as those described in, for example, paragraphs “0072” to “0076” of Japanese Patent Application Laid-Open No. 2004-26373, and thus description thereof is omitted.

  FIG. 9 shows a block diagram of control means used in the duplex printing apparatus 1. In the figure, the control means 129 includes a microcomputer having a CPU 130, ROM 131, and RAM 132 therein, and is provided inside the apparatus main body 11.

The CPU 130 is based on various signals from the operation panel 103, detection signals from various sensors provided in the apparatus main body 11, and an operation program called from the ROM 131, the printing unit 2, the plate making unit 3, the paper feeding unit 4, and the plate ejection. Driving means provided in the image forming unit 5, the paper discharge unit 6, and the image reading unit 7, the driving unit (stepping motor 52, the printing pressure solenoid 181) of the press roller contact / separation mechanism 55 provided in the printing unit 2, and refeeding The operation of the solenoid 33, the suction fan 39, the transport unit drive motor 122, the solenoid 123 that operates the switching member 10 and the like provided in the means 9 are controlled to control the operation of the entire duplex printing apparatus 1.
The ROM 131 stores an operation program for the entire duplex printing apparatus 1, and this operation program is appropriately called by the CPU 130. The RAM 132 has a function of temporarily storing calculation results of the CPU 130, a function of storing data signals and on / off signals set and input from various keys and various sensors on the operation panel 103 as needed. The control unit 129 also grasps the position of the plate cylinder 12 based on a home position signal from the home position sensor 134 and a signal from an encoder sensor (not shown) provided in the plate cylinder driving unit 121.

Based on the above-described configuration, the operation of the duplex printing apparatus 1 in a state where the paper receiving tray 40 is not provided will be described below.
The user stacks the paper P to be used for printing on the paper feed tray 67, opens the pressure plate 94 and places a document to be printed on the contact glass 93, and then closes the pressure plate 94 again. Thereafter, after setting the plate making conditions with various keys on the operation panel 103, the duplex printing key 117 or the simplex printing key 118 is pressed to set one of the print modes, and the plate making start key 104 is pressed. First, the case where single-sided printing is performed by pressing the single-sided printing key 118 is the same as that described in paragraphs “0080” to “0094” of Japanese Patent Application Laid-Open No. 2004-26373, and thus the description thereof is omitted. To do.

  When the user sets plain paper or thin paper P on the paper feed tray 67 and confirms that the user is in the double-sided printing mode by turning on the LED 117a, when the plate making start key 104 is pressed, the single-sided printing is performed. Similarly to the time, a sheet size detection signal and a document size detection signal are sent from the sensors 73 and 102 to the control unit 129, and the control unit 129 compares the input signals. In this example, since the maximum paper size that can be printed by the plate cylinder 12 is A3 size, the paper size that can be used during duplex printing is up to A4 landscape orientation. As a result of comparing the document size and the paper size, if both sizes are the same, the image reading operation is immediately performed. If the two sizes are different, the control unit 129 displays a message to that effect on the display device 120 as a warning. Call attention to the user.

  When the plate making start key 104 is pressed, the image reading unit 7 reads the first original image as in the case of single-sided printing. The read original image is stored in the image memory 135 as the first image data signal. When the reading operation of the first document is completed and the image data signal is stored in the image memory 135, the control means 129 displays a message “Please set the second document” on the display device 120. To do. In accordance with this display, the user opens the pressure plate 94, removes the first original from the contact glass 93, places the second original, and closes the pressure plate 94 again. When a sensor (not shown) detects that the pressure plate 94 is closed and another sensor (not shown) detects that there is a document on the contact glass 93, the reading operation of the second document is performed in the same manner as the first sheet. Is called. The read document image is stored in the image memory 135 as a second image data signal.

  In this example, the document reading operation is performed by the user when the single-sided printing mode is set (hereinafter also referred to as “single-sided printing mode”) and the double-sided printing mode is set (hereinafter also referred to as “double-sided printing mode”). The document that is read on the contact glass 93 is set by opening and closing 94, but the document is automatically conveyed onto the contact glass 93 by using an ADF, or an image from an external device (for example, a computer) (not shown). It is good also as a structure which takes in data. Further, in the duplex printing mode, one original may be reversed and conveyed, and image data for two sheets may be acquired from the front and back surfaces.

  In parallel with the image reading operation in the image reading unit 7, the plate discharging unit 5 performs the plate discharging operation in the same manner as in single-sided printing. The plate cylinder 12 from which the used master 64c has been peeled off from the outer peripheral surface is stopped at the plate feed standby position, and the clamper 19b is opened by an opening / closing means (not shown). In parallel with this plate removal operation, the plate making unit 3 performs a plate making operation. The plate making operation is performed in the same procedure as in the single-sided printing mode, but the first plate making image 65A and the second plate making image 65B are formed on the surface of the thermoplastic resin film of the master 64. At this time, the images 65A and 65B are made so that a predetermined blank portion S is provided between the first plate-making image 65A and the second plate-making image 65B as shown in FIG. The predetermined blank portion S is located at a position corresponding to the intermediate region shown in FIG. 1 when the divided plate-making master 65 is wound on the outer peripheral surface of the plate cylinder 12.

The divided prepress master 65 on which the prepress images 65A and 65B are formed is stored in the master stock unit 61, and when the duplex operation is completed and the duplex printing apparatus 1 is in the plate feed standby state, the reverse roller pair 63 is operated. The divided master-making master 65 is transported between the stage portion 19a and the open clamper 19b. Thereafter, the plate cylinder 12 is intermittently rotated in the same manner as in the single-sided printing mode, so that the divided plate-making master 65 is wound around the plate cylinder 12. When all the two pieces of image data are sent from the image memory 135, the cutting means 60 is activated and the divided master-making master 65 is cut. The cut divided plate-making master 65 is pulled out from the plate-making unit 3 by the rotation of the plate cylinder 12, and the plate cylinder 12 is stopped at the home position to complete the plate-making operation and the plate-feeding operation.
Subsequent to the plate feeding operation, printing operation and trial printing are performed. The printing operation is the same as that described in paragraphs “0101” to “0114” of JP-A-2004-26373, and the test printing operation is described in paragraphs “0115” to “0120” of the same publication. Since they are the same as those described above, their descriptions are omitted.

When the position or density of the image is confirmed by trial printing, and the print start key 105 is pressed after the number of prints is input by the ten key 109, a normal printing operation is performed. In this example, a case where N sheets are input as the number of printed sheets will be described.
When the printing start key 105 is pressed, as in the case of printing and trial printing, when the plate cylinder 12 stops at the home position, the stepping motor 52 is actuated to rotate the step cam 49 and the printing pressure solenoid 181 is turned on. Actuated to bring the cam portion 49a into contact with the cam follower 48c. As a result, the movable arm 48 is swung around the support shaft 48a and the cam shaft 44 is moved to a position where the cam plate 43B can be brought into contact with the cam follower 41, and then the operation of the printing pressure solenoid 181 is released. The

  Thereafter, the sheet feed roller 68, the separation roller 69, the drive rollers 36 and 87, and the suction fans 39 and 90 are respectively driven and the plate cylinder 12 is set at a set printing speed (hereinafter referred to as “set speed”). 1 is rotated in the clockwise direction, and the first sheet P is pulled out from the sheet feed table 67, and the leading end thereof is at the nip portion of the registration roller pair 71 (hereinafter also simply referred to as “registration roller pair 71”). It is applied and temporarily retained. When the clamper 19b passes the position corresponding to the switching member 10, the solenoid 123 is actuated to position the switching member 10 at the second displacement position, and then the divided plate-making master 65 wound on the plate cylinder 12 is used. The drive roller 71a is rotationally driven at a predetermined timing when the leading edge of the image area of the first plate-making image 65A in the plate cylinder rotation direction reaches the position corresponding to the press roller 13, so that the first sheet pulled out P is fed between the plate cylinder 12 and the press roller 13.

  The cam plate 43B moved to a position where it can come into contact with the cam follower 41 at the predetermined timing disengages its convex portion from the cam follower 41, and the press roller 13 presses the peripheral surface by the biasing force of the printing spring 42. Press contact with the outer peripheral surface of the body 12. The first sheet P thus fed is pressed against the first plate making image 65A of the divided plate making master 65 by the press roller 13, thereby printing an image corresponding to the first plate making image 65A on the surface thereof. Thus, the first surface-printed paper PA is obtained.

  The first surface-printed paper PA is re-supplied by the switching member 10 occupying the second displacement position while being peeled from one end of the switching member 10 from the divided plate-making master 65 on the outer periphery of the plate cylinder. Guided to paper means 9. The surface-printed paper PA guided downward by the switching member 10 passes between the guide plates 27 and 56, has one end abutting against the end fence 8 a, and is placed on the auxiliary tray 8. The surface-printed paper PA conveyed on the auxiliary tray 8 is conveyed in the direction of the arrow in FIG. 1 while being held by the endless belt 38 by the suction force of the suction fan 39, and the other end (when the first plate-making image 65A is printed). The rear end is brought into contact with the refeed positioning member 24. At this time, the sensor 8c detects the other end of the surface-printed paper PA, and a detection signal from the sensor 8c is output to the control unit 129, so that a command is sent from the control unit 129 and the drive roller 36 and the suction unit are sucked. The operation of the fan 39 is stopped.

  The plate cylinder 12 continues to rotate while the first surface-printed paper PA is being guided on the auxiliary tray 8, and the cam plate comes into contact when the press roller 13 finishes contacting the surface area of the plate cylinder 12. The convex portion 43B abuts the cam follower 41 to occupy the separated position. Due to the function of the cam plate 43B, the back surface region of the plate cylinder 12 and the press roller 13 are not in pressure contact with each other in the absence of the paper P, and ink transfer to the peripheral surface of the press roller 13 can be prevented. At this time, after the printing pressure solenoid 181 is actuated to hold the press roller 13 at the separated position, the stepping motor 52 is actuated to rotate the step cam 49 and bring the cam portion 49b into contact with the cam follower 48c. As a result, the moving arm 48 is swung around the support shaft 48a, and the cam shaft 44 is moved to a position where the cam plate 43A can be brought into contact with the cam follower 41.

  Further, the paper feed roller 68 and the separation roller 69 are driven almost simultaneously with the above-described operation, and the second paper P is drawn from the paper feed table 67 and the leading end of the paper P is applied to the registration roller pair 71. Then, the driving roller 71a is rotationally driven at the same predetermined timing as described above, and the drawn second sheet P is fed between the plate cylinder 12 and the press roller 13.

  On the other hand, in the press roller contact / separation mechanism 55, when the cam shaft 44 rotates to a position where the convex portion of the moved cam plate 43A can come into contact with the cam follower 41, the operation of the printing pressure solenoid 181 is released. At this time, the plate cylinder 12 rotating in synchronization with the cam shaft 44 occupies a position where the non-opening portion which is a portion other than the front surface region, the back surface region, and the intermediate region faces the press roller 13. Further, the solenoid 123 is operated until the surface region of the plate cylinder 12 passes through the portion facing the press roller 13 and the clamper 19b again occupies the position corresponding to the switching member 10, and the switching member 10 is moved to the second state. It is displaced from the displacement position to the first displacement position.

  Also, almost simultaneously with this operation, the second sheet P is fed from the sheet feeding unit 4 and the second sheet P is temporarily stopped by the registration roller pair 71 and then at the same timing as the first sheet P. It is fed toward the printing unit 2. The switching member 10 is positioned at the first displacement position so as to avoid a collision with the clamper 19b, and is then positioned again at the second displacement position after passing through the clamper 19b.

  The fed second sheet P is pressed against the first plate-making image 65A of the divided plate-making master 65 by the press roller 13, and an image corresponding to the first plate-making image 65A is printed on the front surface. After the printed paper PA is obtained, it is guided to be peeled off by the switching member 10 occupying the second displacement position and conveyed onto the auxiliary tray 8. At this time, the solenoid 33 is operated at the same timing as the trial printing, and the swing arm 32 is swung in the clockwise direction in FIG. 2 about the support shaft 32a. As a result, the re-feeding registration roller 23 is swung from the separation position to the press-contact position, and the first front-side printed paper PA that is stopped with the other end in contact with the re-feeding positioning member 24 is By being brought into contact with the peripheral surface of the press roller 13 rotating at a substantially same peripheral speed as the peripheral speed of the plate cylinder 12, the paper is fed again and conveyed to the printing unit 2 while being reversed. In the first surface-printed paper PA, after the rear end of the second surface-printed paper PA has passed through the contact portion between the plate cylinder 12 and the press roller 13, the intermediate area of the plate cylinder 12 is the press roller. 13 is sent to the abutting portion between the plate cylinder 12 and the press roller 13 at a timing when the back surface region faces the press roller 13 through a position opposite to the press roller 13, and the press plate 13 causes the second plate-making image of the divided plate-making master 65. By being in pressure contact with 65B, an image corresponding to the second plate-making image 65B is printed on the back surface of the printed paper PB.

  During the above-described operation, the solenoid 123 is actuated immediately before the intermediate region of the plate cylinder 12 occupies a position facing the press roller 13, and the switching member 10 is displaced from the second displacement position to the first displacement position. As a result, the rear end (the other end) of the second front surface printed paper PA guided by the switching member 10 passes through a slight gap between the lower surface 10 a of the switching member 10 and the peripheral surface of the press roller 13. Then, the leading end (one end) of the first printed sheet PB that has been guided onto the auxiliary tray 8 and subsequently conveyed is guided along the upper surface 10 b of the switching member 10 to the paper discharge conveying unit 85. . The first printed paper PB is peeled off from the divided plate-making master 65 by the peeling claw 84, then transported by the paper discharge transport unit 85, and discharged onto the paper discharge tray 86.

  After that, the third sheet P is fed from the sheet feeding unit 4, and the third sheet P is temporarily stopped by the registration roller pair 71 and then printed at the same timing as the first and second sheets P. It is fed toward part 2. The switching member 10 is positioned at the first displacement position to avoid a collision with the clamper 19b, and is positioned again at the second displacement position after passing through the clamper 19b. The fed third sheet P is printed on the front surface with an image corresponding to the first plate-making image 65 </ b> A to become a surface-printed sheet PA, and is then guided onto the auxiliary tray 8 by the switching member 10. Then, the solenoid 33 is actuated at a predetermined timing, and the second surface-printed paper PA stopped on the auxiliary tray 8 is conveyed to the printing unit 2.

  The second front-side printed paper PA is sent to the contact portion between the plate cylinder 12 and the press roller 13 at the same timing as the first front-side printed paper PA, and corresponds to the second plate-making image 65B on the back side. The printed image is printed and becomes the second printed paper PB. The switching member 10 is displaced from the second displacement position to the first displacement position at the same timing as described above, and the rear end (the other end) of the third front surface printed paper PA is pressed with the lower surface 10a of the switching member 10 and the press. It is guided onto the auxiliary tray 8 through a slight gap with the peripheral surface of the roller 13. Following this, the leading end (one end) of the second printed sheet PB conveyed from the auxiliary tray 8 is guided along the upper surface 10b of the switching member 10 to the paper discharge conveying unit 85. The printed paper PB of the eyes is peeled off from the divided plate-making master 65 by the peeling claw 84, transported by the paper discharge transport unit 85, and discharged onto the paper discharge tray 86.

  Thereafter, the same printing operation as described above is performed up to the (N-1) th sheet. Then, the Nth sheet P is fed from the sheet feeding unit 4, and an image corresponding to the first plate-making image 65A is printed on the surface thereof, and is guided onto the auxiliary tray 8 as the Nth surface printed sheet PA. After that, the (N−1) th front-side printed paper PA is printed with an image corresponding to the second plate-making image on the back side thereof as the (N−1) th printed paper PB on the discharge tray 86. Is discharged, the printing pressure solenoid 181 is actuated to hold the press roller 13 in the separated position, and the cam shaft 44 is moved to a position where the cam plate 43C can be brought into contact with the cam follower 41. The operation of the pressure solenoid 181 is released. At this time, the switching member 10 maintains the state of occupying the first displacement position.

  Then, the cam follower 41 can be brought into contact with the cam follower 41 at the first timing earlier than the leading end of the image area of the second plate-making image 65B in the plate cylinder rotation direction of the divided plate-making master 65 reaches the position corresponding to the press roller 13. The cam plate 43 </ b> C moved to the position disengages the convex portion from the cam follower 41, and the press roller 13 presses the peripheral surface thereof against the outer peripheral surface of the plate cylinder 12 by the biasing force of the printing pressure spring 42. Thereafter, the solenoid 33 is actuated at a second timing slightly earlier than the leading edge of the image area of the second plate-making image 65B in the plate cylinder rotation direction of the divided plate-making master 65 arrives at the position corresponding to the press roller 13, and the oscillation is changed. The moving arm 32 is swung clockwise around the support shaft 32a in FIG. As a result, the re-feed registration roller 23 is swung from the separation position to the press-contact position, and the N-th surface printed paper PA that has been stopped with the other end in contact with the re-feed positioning member 24 is The paper is re-fed to the printing unit 2 while being reversed by being brought into contact with the peripheral surface of the press roller 13 rotating at the same peripheral speed as the peripheral speed of the plate cylinder 12.

  The N-th surface printed paper PA is sent to the contact portion between the plate cylinder 12 and the press roller 13 at the same timing as the first surface-printed paper PA, and corresponds to the second plate-making image 65B on the back surface thereof. The printed image is printed and becomes the Nth printed paper PB. The Nth printed paper PB is guided to the paper discharge conveyance unit 85 along the upper surface 10 b of the switching member 10, and is peeled off from the divided plate-making master 65 by the peeling claw 84 and then conveyed by the paper discharge conveyance unit 85. The paper is discharged onto a paper discharge tray 86. Thereafter, when the press roller 13 finishes contact with the back surface region of the plate cylinder 12, the convex portion of the cam plate 43C comes into contact with the cam follower 41 to occupy the separated position. Due to the function of the cam plate 43C, the surface region of the plate cylinder 12 and the press roller 13 are not pressed against each other in the absence of the paper P, and ink transfer to the peripheral surface of the press roller 13 can be prevented. At this time, the printing pressure solenoid 181 is actuated to hold the press roller 13 in the separated position, and then the plate cylinder 12 stops at the home position, and the duplex printing apparatus 1 finishes the printing operation and again enters the print standby state.

  According to this double-sided printing apparatus 1, for example, the same advantages and effects as described in paragraphs “0131” to “0133” of JP-A-2004-26373 are obtained.

However, the above-described double-sided printing apparatus 1 has the following problems during continuous printing.
During the above-described printing operation, when the second sheet P passes through the nip portion between the plate cylinder 12 and the press roller 13 and is sent to the auxiliary tray 8 as the second surface-printed sheet PA2, The first surface-printed paper PA 1 is fed toward the nip portion between the plate cylinder 12 and the press roller 13. At this time, as shown in FIG. 10, one end of the front surface-printed paper PA2 comes into contact with one end side of the front surface-printed paper PA1, thereby rubbing and smearing at one end and the back surface of the front surface-printed paper PA2. In addition, there is a problem that the one end side of the surface-printed paper PA1 is also rubbed and smeared.

  At this time, one end of the surface printed paper PA2 must be conveyed toward the left in the figure, but one end of the paper contacts the one end of the surface printed paper PA1 conveyed toward the right in the figure. In addition, due to the adhesive force of the ink on the surface-printed paper PA1 and the conveyance force to the right in the figure, the conveyance force to the left in the figure of the paper P is canceled, and the surface-printed paper PA2 stops on the spot and is conveyed There is a problem that jam occurs.

  Further, FIG. 11 shows a state in which the plate cylinder 12 is slightly rotated from the state shown in FIG. 10, but the surface-printed paper PA2 sent is the state where the surface-printed paper PA1 is sent and there is no paper. It is dropped on the auxiliary tray 8 and is attracted onto the auxiliary tray 8 by the suction force of the operating suction fan 39, and the conveying force to the left in the figure is canceled out by the frictional force of the endless belt 38. There is a problem that conveyance of the printed paper PA2 is hindered and a conveyance jam occurs.

  In order to solve the above-described problems, the paper tray 40 shown in FIG. 1 is provided on the auxiliary tray 8 in this example. Hereinafter, the paper tray 40 used in the first example will be described. The paper receiving tray 40 has a function as a paper receiving means for receiving the leading edge of the front surface printed paper PA 2 guided toward the auxiliary tray 8 by the switching member 10.

  As shown in FIG. 3, the paper tray 40 having a U-shaped cross section has protrusions 40a, 40b, 40c, and 40d on both sides thereof, and the protrusions 40a, 40b, 40c, and 40d are formed on the transport unit main body 35. Are fitted in long holes (not shown) formed in both side plates. In addition, a notch 40e as a fitting portion into which each end fence 8a can be fitted is formed at one end portion of the paper tray 40, and both sides of the paper tray 40 extend to the other end side. Each rack portion 40f is formed. The paper tray 40 is disposed at a position spaced above the endless belts 38. The distance between the lower surface of the paper trays 40 and the endless belts 38 allows the surface-printed paper PA to be transported well on the endless belts 38. The predetermined interval is set to be possible.

A stepping motor 138 having two pinions 139 on an output shaft 138 a is attached to the outside of one side plate of the transport unit main body 35. The front end of the output shaft 138a is rotatably supported by the other side plate of the transport unit main body 35, and each pinion 139 is a position in the vicinity of the both side plates of the transport unit main body 35 and a position that meshes with each rack portion 40f. It is arranged.
In the vicinity of the stepping motor 138, a home position sensor 140 for detecting the home position of the paper tray 40 is disposed. The home position sensor 140 is disposed at a position where the protruding portion of the protrusion 40 d can be detected, and a signal from the home position sensor 140 is output to the control means 129.

With the above-described configuration, the paper tray 40 receives the one end of the surface-printed paper PA2 conveyed from the printing unit 2 closest to the press roller 13 by the stepping motor 138, and is the first position as the home position shown in FIG. And the other end of the surface-printed paper PA2 that is furthest from the press roller 13 and placed on the upper surface thereof is reciprocated to selectively occupy the second position shown in FIG. The
As described above, the stepping motor 138, each pinion 139, and each rack portion 40f have a function as a moving unit that reciprocates the paper tray 40 between the first position and the second position.

  The length of the paper tray 40 in the paper transport direction is such that the paper tray 40 occupies the second position, and the other end of the surface-printed paper PA2 on the paper tray 40 is endless from the paper tray 40. When the surface-printed paper PA2 falls on the belt 38 and is transported by the refeed transport unit 25 and the other end contacts the refeed positioning member 24, one end of the front-printed paper PA2 is a paper cradle. 40 is set to fall from above.

  The function of the paper tray 40 can prevent contact between the surface-printed paper PA1 and the surface-printed paper PA2 during continuous printing. One end and the back of the surface-printed paper PA2 and the surface-printed paper The occurrence of rubbing dirt on one end side of PA1 can be prevented, and the occurrence of conveyance jam can be prevented by conveying the surface-printed paper PA2 well.

Further, the operation of the stepping motor 138 for reciprocating the paper tray 40 is controlled by the control means 129 based on the signal from the sensor 8c, and the paper tray is detected when the front end of the surface printed paper PA1 is detected by the sensor 8c. It can also be set as the structure which moves 40 from a 2nd position to a 1st position. As a result, the surface-printed paper PA2 is reliably sucked and conveyed to the refeed conveyance unit 25, the other end abuts against the refeed positioning member 24, and one end of the sheet PA2 falls from the paper pedestal 40 and then the paper cradle. 40 is moved from the second position to the first position, so that the interference between the paper receiving tray 40 and the surface-printed paper PA2 can be surely prevented, and the occurrence of a paper transport jam can be surely prevented. can do.
Furthermore, since the paper tray 40 has a notch 40e that can be fitted to each end fence 8a at one end thereof, one end of the surface-printed paper PA1 is located between the end fence 8a and the paper tray 40. Therefore, it is possible to prevent the sheet conveyance jam from occurring.

  14 and 15 show a paper receiving tray 140 as a paper receiving means used in the second example. Compared with the paper tray 40 shown in the first example, the paper tray 140 does not have a notch as a fitting portion, and the projections 140a, 40b, 40c, 40d are the same as the projections 40a, 40b, 40c, 40d. 140b, 140c, 140d and the rack part 140f similar to the rack part 40f, the difference is that it has a pair of side fences 140e and two end fences 140g, and other configurations are the same. . In the second embodiment, the auxiliary tray 8 does not have the end fence 8a.

  Also in the paper tray 140, the length in the paper transport direction is that the paper tray 140 occupies the second position, and the other end of the front surface printed paper PA on the paper tray 40 is the paper tray 140. One end of the surface-printed paper PA is dropped onto the endless belt 38 from above, and when the surface-printed paper PA is transported by the re-feed transport unit 25 and the other end contacts the re-feed positioning member 24. Is set to a length that drops from the paper tray 140.

That is, in FIG. 14, the distance L2 from the end of the sheet placement surface of the sheet receiving base 140 that occupies the second position with respect to the sheet conveying direction length L1 of the front surface printed sheet PA to the refeed positioning member 24. It is set to be large. The difference between L1 and L2 is suitably about 10 to 20 mm.
With this configuration, the surface-printed paper PA is transported while the position in the width direction is determined by each side fence 140e and the position in the transport direction is determined by the end fence 140g. The occurrence of skew and misalignment of the surface-printed paper PA when dropped onto the tray 8 can be effectively prevented, and the occurrence of paper conveyance jam can be prevented.

FIG. 16 shows a sheet receiving table 141 as a sheet receiving means used in the third example. The sheet receiving table 141 has protrusions 141a, 141b, 141c, and 141d similar to the protrusions 140a, 140b, 140c, and 140d as compared with the sheet receiving table 140 shown in the second example, and a pair of side fences 140e. Are different in that they have two end fences 141f similar to a pair of side fences 141e and two end fences 140g, and the other configurations are the same. In the third embodiment, the auxiliary tray 8 does not have the end fence 8a, and the drive mechanism of the sheet receiving base 141 is also different. Further, the arrangement position of the cleaning roller 26 is also different, and the guide plate 27 is not provided.
Each protrusion 140a, 140b, 140c, 140d is fitted in a long hole 35c formed in both side plates 35b (see FIG. 17) of the transport unit body 35. The long hole 35b is formed so as to be inclined as much as possible along the dropping path of the surface-printed paper PA that falls from the printing unit 2 onto the auxiliary tray 8.

FIG. 17 shows the drive mechanism of the paper tray 141 in the third example. A first pulley 142 and a second pulley 143 are rotatably supported near the position where the elongated hole 35c is formed between the side plates 35b, and an endless belt 144 is stretched between the pulleys 142 and 143. Yes. A guide roller 145 that is rotatably supported between both side plates 35b is disposed inside the endless belt 144, and the endless belt 144 has substantially the same shape as the long hole 35c below the long hole 35c. It is arranged to be. Further, the endless belt 144 is fixed with a mounting portion 141g formed integrally with the paper tray 141.
A driving gear 146 is attached to a support shaft (not shown) of the first pulley 142, and this driving gear 146 is a pinion 148 attached to an output shaft 147a of a stepping motor 147 that can be rotated forward and backward attached to one side plate 35b. Is engaged.

With the above-described configuration, the sheet receiving base 141 receives the one end of the surface-printed paper PA indicated by a solid line in FIG. 16 by the forward / reverse operation of the stepping motor 147, and the upper surface indicated by a two-dot chain line in FIG. The top surface printed paper PA reciprocates so as to selectively occupy the second position where the other end of the paper PA contacts the endless belt 38. In addition, a home position sensor 149 is provided in the vicinity of the second pulley 143 for detecting when the paper tray 141 occupies the first position, which is the home position.
As described above, the paper tray 141 receives the front end of the surface-printed paper PA2 guided to the auxiliary tray 8 by the switching member 10 at the first position near the printing unit 2, and re-feeds the paper from the first position. It has a function as a paper receiving means for opening the front end of the surface-printed paper PA2 at the second position near the upstream side of the means 9. Further, the stepping motor 147, the drive gear 146, the pinion 148, the first pulley 142, the second pulley 143, the endless belt 144, and the guide roller 145 move the paper tray 141 between the first position and the second position. It has a function as a moving means to reciprocate.

  According to the third example, since the reciprocating path of the paper receiving base 141 is inclined as much as the dropping path of the surface-printed paper PA to the auxiliary tray 8, printing is performed in the printing unit 2. The surface-printed paper PA is transported while being received by the paper cradle 141 in a state close to its moving path, so that the surface-printed paper PA can be smoothly received on the upper surface of the paper cradle 141. Even if there are variations in image conditions, environmental conditions, etc., it is possible to suppress the occurrence of conveyance jams.

  The sheet receiving means and the moving means are not limited to those described above. For example, as shown in FIGS. 1 to 9 of Japanese Patent Application Laid-Open No. 2005-262730, a movement guide as a sheet holding means instead of the sheet receiving means. (81) and moving means (87). According to the double-sided printing apparatus described in the above publication, even with a weak paper, the leading edge of the sheet can be inserted without resistance, and the leading edge of the surface-printed sheet can be clamped reliably and satisfactorily, and the installation space can be increased. The conventional one-plate cylinder 1-pressing means capable of suppressing the double-sided printing apparatus that is more simplified than the one-step double-sided printing apparatus of the double-sided printing method, that is, the refeed storage means in the conventional double-sided printing apparatus is unnecessary. A new double-sided printing device can be provided, and the surface-printed paper fed from the printing unit can be prevented from contacting the surface-printed paper in the paper refeeding unit, and the surface-printed paper can be rubbed and stained. Can be prevented from being jammed, and the surface-printed paper can be prevented from meandering or skewing. Can be favorably transported in a stable state, thereby tilting the printed image during printing, an effect that such inclination can be prevented that would resist is deteriorated under.

(First embodiment)
With reference to FIG. 18 and FIG. 19, the skip sheet feeding operation at the time of duplex printing according to the first embodiment will be described.
Hereinafter, a first embodiment applied to the double-sided printing apparatus 1 provided with the paper tray 141 of the third example will be described. In FIG. 18 and FIG. 19 and the printing states and simplified timing charts shown in FIGS. 20 to 21 according to embodiments described later, “drum rotation” refers to the rotation of the plate cylinder 12 and the drum speed. Represents the rotational speed of the plate cylinder 12, that is, the printing speed. As for the drum speed (printing speed), in order to facilitate understanding of the present invention, the description will be made at a first speed of 60 rpm which does not perform a slow-up (acceleration) operation at the start of printing. In addition, a double-headed arrow of “paper feed (paper feed tray)” indicates a feeding period of the paper P from the paper feed tray 67, and a double-headed arrow of “paper tray” indicates the front-side printed paper PA on the paper tray 141. The conveyance period, the double-headed arrow for “re-feeding registration member” indicates the operation period of the re-feeding registration roller 23, and the “printing solenoid state” indicates ON / OFF (operation / non-operation) of the printing pressure solenoid 181. To express.
In the following simplified timing charts shown in FIGS. 18 to 21, only the operation timings of main components, members, and driving means are illustrated, but the present invention is not limited to this, and the double-sided printing apparatus 1 described above is used. It goes without saying that other components and driving means are included. Further, in the embodiment shown in FIGS. 18 to 21 below, the skip paper feed mode is set at the time of double-sided printing. For simplicity of explanation, the number of double-sided printed sheets will be limited to a small number. Of course, this is not the case.

The function of the operation panel 103 in this embodiment will be supplementarily described. The display device 120 includes an LCD (liquid crystal display device) and has a hierarchical display structure. That is, by appropriately selecting and pressing the selection setting keys 120a, 120b, 120c, and 120d provided below the display device 120, various modes such as zooming and position adjustment, or a skip sheet feeding mode described later are entered. Change and various settings in each mode are possible. The display device 120 functions as a setting unit for various modes displayed by pressing one of the selection setting keys 120a, 120b, 120c, and 120d, in addition to a function as a reporting unit or a display unit for reporting or displaying information. Also have.
Here, for example, the selection setting key 120a of the selection setting keys 120a, 120b, 120c, and 120d temporarily stops the feeding of the paper P from the paper supply unit 4 during duplex printing (when the duplex printing mode is set). And has a function as a skip sheet feeding mode setting means for setting a skip sheet feeding mode in which the printing pressure solenoid 181 of the press roller contact / separation mechanism 55 is turned on to idle the plate cylinder 12. The numeric keypad 109 and the enter key 110 are used for skip feeding for setting the number of times (or the number of sheets fed) for temporarily stopping the feeding of the paper P from the paper feeding unit 4 or the number of idling times for idly rotating the plate cylinder 12. It has a function as a paper number setting means.

The skip sheet feeding operation in the known single-sided printing mode is performed as follows. In the single-sided printing mode setting state, that is, in the lighting state of the LED 118a, for example, the “skip paper feeding mode” is displayed on the display device 120 corresponding to the selection setting key 120a. When the mode display is reversed in black and white, a skip paper feed mode signal for single-sided printing is generated. When this signal is input to the control means 129 shown in FIG. 9, the single-sided printing skip paper feed mode is set.
Next, the number of skip feeds is set with the numeric keypad 109, the skip feed number is displayed on the display device 120, and then the enter key 110 is pressed to set the skip feed number (skip feed number) desired by the user. Is completed. The skip paper feed operation is performed by temporarily stopping the paper feed from the paper feed unit 4 and turning on the printing pressure solenoid 181 of the press roller contact / separation mechanism 55 corresponding to the number of skip paper feed settings during printing. This is done by holding the roller 13 in the separated position and rotating the plate cylinder 12 idly. Similarly to single-sided printing, the double-sided printing allows skipped paper feeding to be used for drying and fixing printed matter.

As described above, in the setting state of the duplex printing mode in which the LED 117a is lit, for example, the “skip paper feed mode” is displayed on the display device 120 corresponding to the selection setting key 120a. When the skip paper feed mode display is reversed in black and white, a skip paper feed mode signal is generated. When this signal is input to the control unit 129 shown in FIG. 9, the skip paper feed mode setting state for duplex printing is set. .
Next, when the number of skip feeds is set with the numeric keypad 109 and displayed on the display device 120, when the enter key 110 is pressed, the setting of the skip feed number (skip feed number) for duplex printing desired by the user is completed. .
In the double-sided printing mode, after double-sided printing on one sheet of paper P, paper feeding from the paper feeding unit 4 is temporarily stopped for the number of skip paper feeding setting times, and the printing pressure solenoid 181 of the press roller contact / separation mechanism 55 is turned on. When the press roller 13 is held at the separation position and the idle rotation of the plate cylinder 12 is completed for the number of skip sheet feeding settings, one sheet P is fed from the sheet feeding unit 4 and duplex printing is performed on the sheet P. By repeating the operation, the skip paper feed printing for double-sided printing is completed.

As shown in FIGS. 18 and 19, during double-sided printing, the first sheet of surface printing paper P in double-sided printing is fed from the paper feed table 67 at the first rotation of drum rotation (plate cylinder 12). At the same time, the plate cylinder 12 is moved to the cam plate 43B in the second rotation, and the front surface is printed on the first fed sheet, which is conveyed to the refeed conveyance unit 25 by the sheet tray 141, The leading edge of the printed paper PA stops at the position of the refeed positioning member 24.
In this embodiment, as described in the third rotation of the drum rotation in FIG. 19, the movement from the cam plate 43B used only for front surface printing to the cam plate 43C used only for back surface printing, and from the cam plate 43C to the cam plate 43B. The mechanism cannot be directly moved and cannot be switched unless it passes through the cam plate 43A for double-sided printing. For this reason, the third rotation of the drum is idle.

In the fourth rotation of the drum, the front-side printed paper PA of the first double-sided printing that has moved to the cam plate 43C and stopped at the position of the refeed positioning member 24 is the refeed registration roller 23. , The front end of the surface-printed paper PA is pressed against the peripheral surface of the press roller 13 rotating at substantially the same peripheral speed as the peripheral speed of the plate cylinder 12, while being reversed along the peripheral surface of the press roller 13. By being fed again to the printing unit 2, the back side of the first sheet of duplex printing is printed, and further guided to the paper discharge transport unit 85 by the switching member 10, and transported by the paper discharge transport unit 85 and discharged to the paper discharge tray 86. Discharged and loaded.
In this embodiment, the number of skip paper feed settings is set to four. However, in the present invention, the setting range of the skip paper feed settings is four or more. This is a setting of four or more because of the mechanism, since four rotations of the plate cylinder 12 are required to print one sheet of duplex printing. FIG. 19 shows a printing operation including skip sheet feeding for one duplex printing, and shows that the number of skip sheet feeding is set to four, that is, four sheet feeding intervals are provided as a duplex printing interval.

  As described above, in the present embodiment, the control unit 129 includes a signal related to the skip paper feed mode setting from the selection setting key 120a, a signal related to the skip paper feed number setting from the ten key 109 and the enter key 110, and the home position sensor 134. Based on a drum rotation position signal and a drum speed signal from an encoder sensor (not shown), a double-sided printing interval corresponding to the skip paper feed number setting is provided, in other words, each driving means shown in FIGS. It has a function of controlling the drive means of the paper feed unit 4, the printing unit 2, the refeed unit 9, the paper discharge unit 6 and the switching member 10 so as to satisfy the operation and timing of the members.

(Second Embodiment)
With reference to FIG. 20 and FIG. 21, a skip sheet feeding operation during duplex printing according to the second embodiment will be described.
As compared with the first embodiment, the second embodiment is a surface skip sheet feeding number setting unit that sets the surface skip sheet feeding number corresponding to the front surface printing when setting the skip sheet feeding mode in duplex printing. For example, when the selection setting key 120b, the numeric keypad 109, the enter key 110, and the skip sheet feeding mode at the time of duplex printing are set, the back skip sheet feeding number setting unit for setting the number of back surface skip sheet feeding corresponding to the back surface printing is used. Signals from the selection setting key 120c, ten key 109 and enter key 110, selection setting key 120a and selection setting key 120b, ten key 109 and enter key 110, selection setting key 120a and selection setting key 120c, ten key 109 and enter key 110 Based on the front skip feed number setting Alternatively, the sheet feeding is performed so that the duplex printing interval corresponding to the setting of the number of skipped sheet feeding on the back surface is provided, in other words, the operation / timing of each driving means, component, member, etc. shown in FIGS. The main difference is that the control unit 129 that controls the drive unit of the unit 4, the printing unit 2, the refeed unit 9, the paper discharge unit 6, and the switching member 10 is mainly used.

As described above, in the display device 120 that is in the skip paper feed mode setting state by pressing the selection setting key 120a in the double-sided printing mode setting state in which the LED 117a is lit, corresponding to the selection setting key 120b. Since the message “Please set the front skip sheet feeding number setting” is displayed, the selection setting key 120b is pressed, and then the front key skip sheet feeding number is set with the numeric key 109 and displayed on the display device 120. Then, when the enter key 110 is pressed, the setting of the number of front side skip feeds (front side skip feed number) for duplex printing desired by the user is completed.
Similarly, in the setting state of the duplex printing mode in which the LED 117a is lit, the display device 120 that is in the skip paper feed mode setting state by pressing the selection setting key 120a corresponds to the selection setting key 120c. The message “Please set the reverse side skip feed number setting” is displayed, so the selection setting key 120c is pressed, and then the reverse side skip feed number is set with the numeric key 109 and displayed on the display device 120. After that, when the enter key 110 is pressed, the setting of the number of back side skip feeds (back side skip feed number) for duplex printing desired by the user is completed. As described above, the present embodiment is greatly different from the first embodiment in that the number of front-side skip feeds and the number of back-side skip feeds are set individually and independently.

  In the first embodiment, the skip paper feed printing in the double-sided printing is performed by repeating the operation of printing one sheet of double-sided printing. Therefore, the interval between the front surface printing and the back surface printing in the double-sided printing is constant and the drum rotation is performed twice. It was minutes. The two rotations of the plate cylinder 12 are constant because they are caused by a unique mechanism of the duplex printing apparatus 1. This suggests that at least three or more sheet feeding intervals are required when setting the skip sheet feeding frequency for each of the front surface printing and the back surface printing in the duplex printing.

As shown in FIG. 20, during double-sided printing, the same operation as in the first embodiment is executed from the first to the third rotation of the drum rotation. That is, the first sheet P for front side printing in double-sided printing is fed from the sheet feed table 67 and moved to the cam plate 43B at the second rotation of the plate cylinder 12 to be fed to the first sheet fed. The front surface is printed, and this is transported to the paper refeeding transport unit 25 by the paper tray 141, and the front end of the surface printed paper PA stops at the position of the paper refeed positioning member 24.
As described above, the third rotation of the drum rotation is a mechanism in which the movement from the cam plate 43B used only for the front surface printing to the cam plate 43C used only for the back surface printing and the movement from the cam plate 43C to the cam plate 43B cannot be performed directly. Since the switching cannot be performed without passing through the cam plate 43A for double-sided printing, the third rotation of the drum is idle. In other words, the third rotation of the drum is switched to the cam plate 43A in preparation for backside printing after switching to the cam plate 43C. The fourth drum rotation is an idling rotation for skip feeding.

At the fifth rotation of the drum rotation, the first surface-printed paper PA that has been moved to the cam plate 43C and stopped at the position of the paper refeeding positioning member 24 is the paper reprinting registration roller 23. , The front end of the surface-printed paper PA is pressed against the peripheral surface of the press roller 13 rotating at substantially the same peripheral speed as the peripheral speed of the plate cylinder 12, while being reversed along the peripheral surface of the press roller 13. By being fed again to the printing unit 2, the back side of the first sheet of duplex printing is printed, and further guided to the paper discharge transport unit 85 by the switching member 10, and transported by the paper discharge transport unit 85 and discharged to the paper discharge tray 86. Discharged and loaded.
After that, at the sixth rotation of the drum rotation, in order to repeat the feeding operation of the paper P for the front side printing of the second double-sided printing, the cam plate passes from the cam plate 43C via the double-sided printing cam plate 43A. Move to 43B. Next, in the seventh rotation of the drum, surface printing of the second double-sided printing is performed in the same manner as described above, and this is conveyed to the paper refeeding conveyance unit 25 by the paper receiving base 141, and the surface of the second sheet is printed. The leading edge of the printed paper PA stops at the position of the refeed positioning member 24. Next, at the eighth and ninth rotations of the drum rotation, the plate cylinder 12 is prepared for idle rotation for skip sheet feeding and preparation for movement to the cam plate 43C, similarly to the first surface-printed sheet PA. , And the second surface-printed paper for double-sided printing in which the leading edge of the second surface-printed paper PA was stopped at the position of the refeed positioning member 24 at the 10th rotation of the drum rotation. As PA is raised, the leading edge of the surface-printed paper PA is pressed against the peripheral surface of the press roller 13 rotating at the same peripheral speed as the peripheral speed of the plate cylinder 12 as the re-feeding registration roller 23 moves up. Is reversed along the peripheral surface of the paper, and is fed again to the printing unit 2, whereby the second side of the double-sided printing is printed, and is further guided to the paper discharge transport unit 85 by the switching member 10, and the paper discharge transport unit Conveyed by 85 It is released and stacked on the paper discharge tray 86 Te. By repeating the above operation, skip paper feed printing in duplex printing is continuously executed.

When the number of front-surface skips set for front-surface printing is 5 by the operation described above, the front-surface-printed paper PA in double-sided printing is the front surface at the position of the re-feed positioning member 24 of the re-feed transport unit 25. The plate cylinder 12 corresponding to the skip count setting (5 times) is stopped for the amount of idle rotation. The printing pressure solenoid 181 shown in FIGS. 20 and 21 is in the second and seventh rotations of the drum rotation, and the printing cam is moved and switched to the cam plate 43B at this time. Only the surface of the paper P is printed.
Further, in the case of the operation of the back side skip count set for 3 times set for the back side printing, the plate cylinder 12 is stopped at the position of the refeed positioning member 24 corresponding to the front side skip count setting (5 times). The front-side printed paper PA that has been printed on the peripheral surface of the press roller 13 that rotates at the same peripheral speed as the peripheral speed of the plate cylinder 12 by the re-feeding registration roller 23 is raised. Is pressed and re-fed along the peripheral surface of the press roller 13 to be fed again to the printing unit 2, whereby the second side of the double-sided printing is printed. The paper is guided, transported by the paper discharge transport unit 85, and discharged / stacked on the paper discharge tray 86. Thereby, back surface printing is performed every 3 times of back surface skips. The printing pressure solenoid 181 shown in FIGS. 20 and 21 is on at the fifth and tenth rotations of the drum rotation, and the printing cam is moved and switched to the cam plate 43C at this time. The printing is performed only on the back surface of the front-side printed paper PA.

As described above, according to the present embodiment, as can be seen in FIGS. 20 and 21, the front surface printing and the back surface printing are individually set with the skip sheet feeding times in the double-sided printing, thereby drying the front surface printing. Since the time setting and the drying time setting for the back side printing can be individually set, the back side printing on the paper discharge tray (discharge tray) 86 can be performed when it is desired to increase the drying of the front side printing in the duplex printing apparatus 1. This makes it possible to make settings such as double-sided printing when you want to shorten the drying time.
Also, by setting the skip feed count for front side printing and back side printing separately for duplex printing, the drying time setting for front side printing and the drying time setting for back side printing can be set individually. When it is desired to shorten the drying of the front surface printing in the printing apparatus 1, it is possible to set the duplex printing when it is desired to increase the drying time of the back surface printing on the paper discharge tray 86. This is very effective when a sorting device such as a sorter is connected to the paper discharge port in place of the paper discharge tray 86.

As described in the first and second embodiments with reference to FIGS. 18 to 21, there are types of skip sheet feeding operations for double-sided printing, each of which has a characteristic. It is troublesome for the user to select the feature and set it when starting double-sided printing.
In view of this, on the display device 120 of the operation panel 103, the double-sided skip feed printing mode selection display corresponding to the type of skip feed operation is displayed on the display device 120 of what kind of double-sided printing the user wants to perform. By selecting with the selection setting keys 120a to 120d, the skip sheet feeding operation for double-sided printing is automatically executed at the start of printing.
At this time, the display device 120 and the selection setting keys 120a to 120d function as a selection unit that selects the double-side skip sheet feeding printing mode corresponding to the type of the skip sheet feeding operation in the first and second embodiments. The control unit 129 shown in FIG. 6 functions as a control unit that performs a skip sheet feeding operation corresponding to the selected double-side skip sheet feeding printing mode based on signals from the selection setting keys 120a to 120d.

Options for the double-side skip paper feed printing mode corresponding to the type of skip paper feed operation include, for example, the following two types of double-side skip paper feed printing mode with the skip paper feed mode set.
In the “Discharge priority double-sided skip paper feed printing mode”, the paper discharge timing during skip paper feed printing in double-sided printing becomes constant regardless of the setting of the number of skip paper feeds. This is an effective printing operation when the paper PB that has been printed is taken out of the paper discharge tray 87 for post-processing. When this is selected, double-sided printing is performed by the double-sided skip feed operation in the first embodiment shown in FIGS.
“Fixed priority double-side skip paper feed printing mode” is the time for drying due to idle rotation of the plate cylinder 12 for the number of times of front-side and back-side skip paper feeding set together with front-side printing and back-side printing during skip-feeding printing in double-sided printing. Therefore, the double-sided printed paper PB discharged and discharged onto the paper discharge tray 87 can be in the same dry / fixed state on both the front and back surfaces. In particular, this is an effective printing operation when double-sided printing is performed on printing paper with poor fixability. When this is selected, skip-feeding of double-sided printing in the second embodiment shown in FIGS. 20 and 21 is performed. Double-sided printing by operation.

  These options “Discharge priority double-side skip paper feed printing mode” and “Fixing priority double-side skip paper feed printing mode” are displayed on the display device 120 of the operation panel 103, and the user uses the selection setting keys 120a to 120d. select. Accordingly, based on the signals from the selected selection setting keys 120a to 120d, the control unit 129 shown in FIG. 9 performs the skip sheet feeding operation selected from the two types of two-sided skip sheet feeding printing modes. By controlling the drive means of the paper feed unit 4, the printing unit 2, the refeed unit 9, the paper discharge unit 6, and the switching member 10, skip feeding corresponding to the double-sided skip paper feed printing mode desired by the user is performed. Automatically changed to paper motion. Thereby, the double-sided printing desired by the user can be automatically performed.

As described above, two types of “discharge priority duplex skip paper feed printing mode” and “fixing priority duplex skip paper feed printing mode” are displayed on the display device 120 of the operation panel 103, and the user selects the selection setting keys 120a to 120a. By selecting at 120d, it is possible to automatically execute the skip feeding operation for duplex printing at the start of printing, but it is troublesome for the user to select and set the printing mode each time.
Therefore, for example, there is provided a changing means for changing the above-described two types of double-side skip paper feed printing mode set in advance as an initial state at the time of installation of the double-side printing apparatus to the always-use double-side skip paper feed print mode. It is possible to make it possible to decide what kind of double-sided printing is desired from now on.

For example, the above-described two types of duplex printing modes are displayed on the display device 120 only as the “fixed priority duplex skip sheet feeding printing mode” as the always-used duplex skip sheet feeding printing mode. Selection is made by the operation of 120d.
At this time, the selection setting keys 120a to 120d function as changing means for changing to the always-used print mode corresponding to the type of the double-side skip paper feed print mode. Based on the output signals from the selection setting keys 120a to 120d, the control unit 129 shown in FIG. 9 performs a skip sheet feeding operation corresponding to the “fixing priority duplex skip sheet feeding printing mode” as the always-used duplex skip printing mode. Thus, it functions as a control means for controlling the respective drive means of the paper feed section 4, the printing section 2, the paper discharge section 6, the refeed means 9, and the switching member 10. Thereby, the skip sheet feeding operation corresponding to the double-side skip sheet feeding printing mode desired by the user is automatically executed.
Of course, the selection setting keys 120a to 120d may be selected again when pressed so that the selection item can be changed.

  The present invention is not limited to the double-sided printing apparatus 1 described above, and can also be applied to, for example, a double-sided printing apparatus having the configuration shown in FIG. 1 of JP-A-2005-262730.

1 is a schematic front view of a duplex printing apparatus showing a first example to which the present invention is applied. It is a schematic front view explaining the press roller spaced apart from the press roller contacting / separating mechanism and the plate cylinder outer peripheral surface used in the first example. FIG. 5 is a schematic plan view for explaining a refeed conveyance unit and a paper tray used in the first example. It is a schematic side view explaining the press roller contact / separation mechanism used for the 1st example. It is a schematic front view explaining the press roller which contacted the press roller contacting / separating mechanism and plate cylinder outer peripheral surface used for the 1st example. It is the schematic explaining the division | segmentation prepress master used for a 1st example. It is the schematic explaining the plate-making completed master used for a 1st example. It is the schematic which shows the operation panel used for a 1st example. It is a block diagram which shows the control structure used for the 1st example thru | or 3rd example, 1st and 2nd embodiment, etc. FIG. It is a schematic front view of the principal part of a printing part for demonstrating the malfunction at the time of continuous printing of the double-sided printing apparatus used for a 1st example. It is a schematic front view of the principal part of a printing part for demonstrating the malfunction at the time of continuous printing of the double-sided printing apparatus used for a 1st example. It is a schematic front view of the principal part of a printing part for demonstrating the continuous printing operation | movement in a 1st example. It is a schematic front view of the principal part of a printing part for demonstrating the continuous printing operation | movement in a 1st example. It is a schematic plan view explaining the paper tray used in the second example. It is a schematic front view of the principal part of a printing part for demonstrating the paper stand used for a 2nd example. It is a schematic front view of the principal part of a printing part for demonstrating the paper stand used for a 2nd example. It is the schematic explaining the drive mechanism of the paper stand used for the 3rd example. It is a figure including the timing chart explaining the operation | movement at the time of 4 sheets of skip sheet feeding frequency of double-sided printing in the 1st Embodiment of this invention. It is a figure including the timing chart explaining the operation | movement at the time of the skip sheet feeding frequency | count of 4 sheets (times) of 1 double-sided printing in the 1st Embodiment of this invention. It is a figure including the timing chart explaining the operation | movement of the number of front surface skip sheet feeding 5 sheets (times) and the back surface skip sheet feeding frequency 3 sheets (times) of the double-sided printing in the 2nd Embodiment of this invention. FIG. 21 is a diagram including a timing chart for explaining the continuation of the operation in FIG. 20.

Explanation of symbols

1 Double-sided printing device 2 Printing section (printing means)
4 Paper feed unit (paper feed means)
6 Paper discharge unit (paper output means)
8 Auxiliary tray (re-feed storage means)
8c Surface-printed paper detection member (sensor)
9 Refeeding means 10 Switching member (switching means)
12 Plate cylinder 13 Press roller (pressing means)
23 Re-feeding registration roller (Re-feeding registration member)
24 Re-feed positioning member 25 Re-feed transport unit 38 Paper transport member (endless belt)
40, 140, 141 Paper receiving tray (paper receiving means)
40e Fitting part (notch part)
65 Master for split plate making 65A First plate making image 65B Second plate making image 103 Operation panel 109 Numeric keypad (skip feed number setting means, front / back side feed number setting means)
110 Enter key (skip feed number setting means, front / back side feed number setting means)
129 Control means 120 Display device (Skip paper feed mode setting means, Front / back side paper feed number setting means, Change means, Notification means, Display means)
120a to 120d selection setting keys (skip feed mode setting means, front / back side feed count setting means, change means)
138, 147 Stepping motor (moving means)
P paper PA front-side printed paper PB printed paper

Claims (4)

Relative to the plate cylinder and the plate cylinder around which the divided plate-making master, in which the first plate-making image and the second plate-making image are formed side by side along the rotation direction of the plate cylinder, is wound. A printing unit having a detachable pressing unit, a paper feeding unit for feeding paper toward the printing unit, a paper discharge unit for discharging printed paper printed by the printing unit, and a printing unit Temporarily holding the surface-printed paper on which the printed image is formed on the surface corresponding to the first plate-making image or the second plate-making image, and then feeding the surface-printed paper toward the pressing means; A refeeding unit that is reversed by the pressing unit and refeeds toward the printing unit; and a switching unit that guides the paper that has passed through the printing unit to the refeeding unit or the discharge unit. ,
During double-sided printing, the first sheet is fed from the sheet feeding unit to the printing unit, and surface printing corresponding to one of the first plate-making image and the second plate-making image is performed on the surface, After the first printed sheet with the front surface printed thereon is guided to the refeeding unit by the switching unit, the second sheet is fed from the sheet feeding unit to the printing unit and the first sheet is printed on the surface. Surface printing corresponding to one of the plate-making image and the second plate-making image is performed, and the first surface-printed paper is re-fed to the printing unit by the re-feeding unit, and the first surface is printed on the back side. Back side printing corresponding to the other one of the plate-making image and the second plate-making image is performed, and the switching unit makes the first double-sided printed paper the above-mentioned paper discharge unit and the second front-side printed paper the above-mentioned paper again. In the double-sided printing device that guides each of the paper feeding means,
A skip paper feed mode setting means for temporarily stopping feeding of the paper from the paper feed means during duplex printing and setting a skip paper feed mode for idly rotating the plate cylinder;
Skip paper feed number setting means for setting the skip paper feed number when setting the skip paper feed mode;
Based on signals from the skip paper feed mode setting means and the skip paper feed frequency setting means, the paper feed means, the printing means, Control means for controlling each of the drive means of the paper discharge means, the refeed means and the switching means;
A double-sided printing apparatus comprising: Relative to the plate cylinder and the plate cylinder around which the divided plate-making master, in which the first plate-making image and the second plate-making image are formed side by side along the rotation direction of the plate cylinder, is wound. A printing unit having a detachable pressing unit, a paper feeding unit for feeding paper toward the printing unit, a paper discharge unit for discharging printed paper printed by the printing unit, and a printing unit Temporarily holding the surface-printed paper on which the printed image is formed on the surface corresponding to the first plate-making image or the second plate-making image, and then feeding the surface-printed paper toward the pressing means; A refeeding unit that is reversed by the pressing unit and refeeds toward the printing unit; and a switching unit that guides the paper that has passed through the printing unit to the refeeding unit or the discharge unit. ,
During double-sided printing, the first sheet is fed from the sheet feeding unit to the printing unit, and surface printing corresponding to one of the first plate-making image and the second plate-making image is performed on the surface, After the first printed sheet with the front surface printed thereon is guided to the refeeding unit by the switching unit, the second sheet is fed from the sheet feeding unit to the printing unit and the first sheet is printed on the surface. Surface printing corresponding to one of the plate-making image and the second plate-making image is performed, and the first surface-printed paper is re-fed to the printing unit by the re-feeding unit, and the first surface is printed on the back side. Back side printing corresponding to the other one of the plate-making image and the second plate-making image is performed, and the switching unit makes the first double-sided printed paper the above-mentioned paper discharge unit and the second front-side printed paper the above-mentioned paper again. In the double-sided printing device that guides each of the paper feeding means,
A skip paper feed mode setting means for temporarily stopping feeding of the paper from the paper feed means during duplex printing and setting a skip paper feed mode for idly rotating the plate cylinder;
Front skip feed number setting means for setting the number of front skip feeds corresponding to the front side printing when the skip feed mode is set;
Back side skip feed number setting means for setting the back side skip feed number corresponding to the back side printing when the skip feed mode is set;
Based on the signals from the skip feed mode setting means and the front skip feed number setting means or the skip feed mode setting means and the back skip feed number setting means, Control means for controlling the respective drive means of the paper feed means, the printing means, the paper discharge means, the refeed means and the switching means so as to leave a double-sided printing interval corresponding to the setting of the number of times of reverse side skip paper feed When,
A double-sided printing apparatus comprising: Selecting means for selecting any one of various skip-feeding printing modes set by the skip-feeding number setting unit, the front-side skip feeding number setting unit, or the back-side skip feeding number setting unit; ,
The control means, based on a signal from the selection means, executes the double-side skip paper feed printing mode selected by the selection means, the paper feed means, the printing means, the paper discharge means, 3. The double-sided printing apparatus according to claim 2, wherein each of the driving means of the refeeding means and the switching means is controlled. The various double-side skip paper feed printing modes are preset as an initial state of the double-sided printing apparatus,
Changing means for changing the various double-side skip paper feed printing modes to a double-side skip paper feed print mode that is always used;
The control means, based on a signal from the changing means, executes the double-side skip paper feed printing mode changed by the changing means, the paper feeding means, the printing means, the paper discharging means, 4. The double-sided printing apparatus according to claim 3, wherein each of the driving means of the refeeding means and the switching means is controlled.

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