JP4355258B2 - Paper feeding device, image forming apparatus, paper feeding method, and image forming method - Google Patents

Description

  The present invention is a paper feeding device for feeding a recording medium once loaded, and in particular, a paper feeding device that engages with the leading end of the recording medium to stop the recording medium, a printing device having the same, etc. The present invention relates to an image forming apparatus, a sheet feeding method using the sheet feeding apparatus, the sheet feeding method, or an image forming method using the image forming apparatus.

  Image forming apparatuses such as printing apparatuses, copiers, facsimiles, and printers form images on a recording medium such as plain paper, and thus a paper feeding apparatus that supplies the recording medium to a predetermined part in the image forming apparatus. Is conventionally used. As one type of such a paper feeding device, as described in [Patent Document 1], the recording medium is temporarily loaded by engaging the leading end of the recording medium and stopping the recording medium, and thereafter There is a type of paper feeding device that feeds paper.

  With regard to this type of paper feeding device, the applicant previously described that in Japanese Patent Application No. 2003-416903, a recording medium that is a problem in the paper feeding device described in [Patent Document 1] is loaded on the paper feeding device. When the recording medium tip is engaged, or when the recording medium is placed on the paper feeding device before this engagement, the recording medium is bent, scratched or broken. In order to prevent this, a technique for controlling the urging force applied to the recording medium when the recording medium is stacked on the sheet feeder main body has been proposed.

JP 2003-200355 A

  However, the technique described in the above Japanese Patent Application No. 2003-416903 has solved the problem, such as bending of the recording medium until the recording medium is stopped by engaging with the leading end of the recording medium. Even after the recording medium is stopped, it cannot be said that sufficient consideration is given. According to such a technique, even after the recording medium is stopped, if the recording medium has a strong stiffness of about 55K or more, which is high-quality paper, the recording medium is bent. However, such a problem can be prevented when a strong recording medium is used. When using a recording medium that is relatively weak such as paper, or when stopping such a recording medium that is particularly stiff and transporting in a direction perpendicular to the direction of its eyes, the recording medium It has been found that there may be problems such as sag in the shape of a scale insect.

  The present invention is a paper feeding device for engaging a leading end of a recording medium to stop the recording medium and feeding the recording medium once loaded, and the deflection of the recording medium after the stop is made. An image forming apparatus such as a printing apparatus having the same, a sheet feeding method using the sheet feeding apparatus, and a sheet feeding method or an image forming method using the image forming apparatus are provided. Objective.

In order to achieve the above object, the invention according to claim 1 is arranged on the upstream side of the locking member in the conveyance direction of the recording medium, and the locking member that engages and stops at the leading end of the recording medium for paper feeding. The recording medium is curved in a manner that forms a convex shape that protrudes from the planar shape that is in close contact with the recording medium conveyance surface and extends in the same conveyance direction on a cross section that is perpendicular to the conveyance direction. A urging member for urging the recording medium toward the recording medium conveying surface; a urging means for conveying the recording medium in the conveying direction until the recording medium engages with the locking member; possess the door, the waist with member, a between the locking member and the conveying means in the conveying direction, is disposed on an extension of said conveying means in the conveying direction, the recording medium transporting surface The height of the seating member of the recording medium from the recording medium conveyance surface In the sheet feeding apparatus than the height of the conveying means.

According to a second aspect of the present invention, in the paper feeding device according to the first aspect, the height of the seating member from the recording medium conveyance surface is equal to or less than the height of the locking member from the recording medium conveyance surface. It is characterized by.

According to a third aspect of the present invention, in the paper feeding device according to the first or second aspect, the locking member is disposed on an extension line of the conveying unit in the conveying direction .

According to a fourth aspect of the present invention, in the paper feeding device according to any one of the first to third aspects, the height of the conveying unit from the recording medium conveying surface is set to the locking member from the recording medium conveying surface. It is characterized by being below the height of .

According to a fifth aspect of the invention, the sheet feeding apparatus according to any one of claims 1 to 4, that the said conveying means and said waist attachment member, a plurality arranged in a direction perpendicular to the transport direction It is characterized by.

According to a sixth aspect of the invention, the sheet feeding apparatus according to any one of claims 1 to 5, characterized in that it has a control means for controlling driving of the conveying means.

According to a seventh aspect of the present invention, in the paper feeding device according to the sixth aspect , the control means is responsive to at least one recording condition among an image forming speed, a recording medium size, a recording medium type, and an environment. The conveyance speed of the recording medium by the conveyance means is changed .

According to an eighth aspect of the present invention, in the paper feeding device according to the sixth or seventh aspect , the control unit is responsive to at least one recording condition among an image forming speed, a recording medium size, a recording medium type, and an environment. The drive stop timing of the conveying means after the recording medium is locked to the locking member is changed .

According to a ninth aspect of the present invention, in the paper feeding device according to any one of the sixth to eighth aspects, the control unit includes: an image forming speed, a size of the recording medium, a type of the recording medium, and an environment. The driving time of the conveying means is changed according to at least one recording condition.

According to a tenth aspect of the present invention, in the paper feeding device according to any one of the sixth to ninth aspects, the control means includes at least one of an image forming speed, a recording medium size, a recording medium type, and an environment. The drive start timing of the transport unit is changed according to one recording condition.

According to an eleventh aspect of the present invention, in the paper feeding device according to any one of the sixth to eighth aspects, the control means passes a predetermined point upstream of the locking member in the recording medium conveyance direction. The time when a predetermined time has elapsed since the start is defined as a stop of the driving of the conveying means.

  A twelfth aspect of the present invention is the paper feeding device according to the eleventh aspect, further comprising recording medium detecting means for detecting a recording medium disposed at the predetermined point, wherein the control means is based on the recording medium detecting means. The drive stop time is determined based on the detection timing of the recording medium.

According to a thirteenth aspect of the present invention, there is provided an image forming apparatus comprising the paper feeding device according to any one of the first to twelfth aspects .

According to a fourteenth aspect of the present invention, in the image forming apparatus according to the thirteenth aspect, the printing apparatus performs recording on a recording medium using a plate cylinder .

According to a fifteenth aspect of the present invention, in the image forming apparatus according to the thirteenth or fourteenth aspect, an image can be formed on both sides of the recording medium, and the paper feeding device is a recording medium on which the image is formed on one side. Then, it is provided as a paper refeeding device on which a recording medium on which image formation is performed is placed on the other surface .

According to a sixteenth aspect of the present invention, there is provided a paper feeding method for feeding paper using the paper feeding device according to any one of the first to twelfth aspects.

A seventeenth aspect of the present invention is an image forming method for forming an image using the image forming apparatus according to any one of the thirteenth to fifteenth aspects or the paper feeding method according to the sixteenth aspect .

The present invention relates to a locking member that engages and stops at the leading end of a recording medium for paper feeding, and a cross section that is disposed on the upstream side of the locking member in the conveyance direction of the recording medium and is perpendicular to the conveyance direction. , and hips with member attached waist by bending the recording medium in a manner to form a convex portion extending in the same conveying direction a convex shape bulging shape from a planar shape portion in close contact with the recording medium transporting surface, recording and conveying means for conveying the transport direction until the medium is engaged with the locking member, have a biasing means for biasing the recording medium to the recording medium transportation surface, the waist with members, The height of the waist member from the recording medium conveying surface is recorded between the conveying means and the locking member in the conveying direction and on an extension line of the conveying means in the conveying direction. KyushiSo that was less than or equal to the height of the conveying means from the medium transporting surface Since the, in transporting until it engages the recording medium to the locking member by the conveying means, the recording medium floats that various programs from the recording medium transporting surface is due to such that it is locked by the waist with member While preventing the recording medium from being poorly transported, scratched, bent, and soiled , the recording medium urged against the recording medium conveying surface can be securely seated with the seating member, and the recording medium can be bent, buckled, It is possible to provide a paper feeding device that can satisfactorily and reliably lock the recording medium by the locking member without causing breakage or the like, and can perform good paper feeding.

  Assuming that a plurality of waisting members and transporting means are arranged in a direction perpendicular to the transporting direction, when the recording medium is transported by the transporting means until it engages with the locking member, the recording medium is transported by the seating member. The recording medium can be satisfactorily seated, and the recording medium can be satisfactorily and reliably locked by the locking member without causing the recording medium to bend, buckle, bend, etc. It is possible to provide a paper feeding device capable of performing

  If the height of the seating member from the recording medium conveyance surface is equal to or less than the height of the locking member from the recording medium conveyance surface, the recording medium is caused by the recording medium floating from the recording medium conveyance surface, etc. The recording medium can be seated with the seating member and the recording medium can be reliably engaged with the locking member, while preventing the conveyance failure, scratches, bending, and dirt of the recording medium. Since the recording medium can be satisfactorily and reliably locked by the locking member without causing the recording medium to be bent, buckled, bent, or the like. A paper feeding device capable of feeding paper can be provided.

  If the height of the conveying means from the recording medium conveying surface is set to be equal to or lower than the height of the locking member from the recording medium conveying surface, the recording medium floats from the recording medium conveying surface when being conveyed by the conveying means. While preventing the recording medium from being poorly transported, scratched, bent, or soiled due to this, the recording medium is seated with the back member, and the recording medium is transported until it is engaged with the locking member. Thus, the recording medium can be satisfactorily and reliably locked by the locking member without causing the recording medium to bend, buckle, bend, or the like. can do.

  If the control means for controlling the driving of the conveying means is provided, the recording medium is seated by the waist member, and the recording medium is conveyed by the conveying means to be engaged with the locking member. Can be controlled in such a manner, and the recording medium can be more reliably and reliably locked by the locking member without causing the recording medium to bend, buckle, bend, etc. It is possible to provide a paper feeding device capable of performing the above.

If the control means changes the conveyance speed of the recording medium by the conveyance means in accordance with at least one recording condition among the image forming speed, the size of the recording medium, the type of the recording medium, and the environment , While the recording medium is seated, the conveyance speed of the recording medium by the conveying means can be controlled to be performed in a good manner by using an appropriate condition for engaging the recording medium with the locking member, To provide a paper feeding device capable of further favorably and surely locking a recording medium by a locking member without causing bending, buckling, bending or the like of the recording medium, and capable of performing good paper feeding. Can do.

The drive stop timing of the conveying means after the control means locks the recording medium to the locking member according to at least one recording condition of the image forming speed, the size of the recording medium, the type of the recording medium, and the environment. If the recording medium is seated by the seating member and the recording medium is transported by the transporting means, it is preferable to use conditions suitable for engaging the recording medium with the locking member. And the recording medium can be controlled so as not to be unnecessarily conveyed by the conveying means after the recording medium is locked by the locking member, and the recording medium can be bent, buckled or bent. Thus, it is possible to provide a sheet feeding device that can more reliably and reliably latch the recording medium by the latching member without causing any problems, and that can perform a good sheet feeding.

  If the control means determines that the passage of a predetermined time from when it passes a predetermined point upstream of the locking member in the conveyance direction of the recording medium is the stop of driving of the conveyance means, The recording medium can be reliably controlled with a predetermined time delay so that the recording medium can be conveyed by the conveying means in a good mode for engaging the recording medium with the locking member. It is possible to provide a paper feeding device capable of better and surely locking a recording medium by a locking member without causing bending, buckling, bending, or the like of the medium, and capable of performing good paper feeding. it can.

  If there is a recording medium detecting means for detecting the recording medium disposed at a predetermined point, and the control means determines when to stop driving based on the detection timing of the recording medium by the recording medium detecting means, The recording medium detection timing by the recording medium detection means so that the recording medium is seated by the attaching member and the recording medium is conveyed by the conveying means in a good mode for engaging the recording medium with the locking member. Can be reliably controlled with a delay of a predetermined time, and the recording medium can be better and reliably locked by the locking member without causing the recording medium to bend, buckle, bend, etc. It is possible to provide a paper feeding device that can perform good paper feeding.

If the control means changes the driving time of the conveying means according to at least one of the recording conditions of the image forming speed, the size of the recording medium, the type of the recording medium, and the environment, the recording medium is moved by the seating member. In addition to being seated and without using the recording medium detection means, the conveying time of the recording medium by the conveying means is performed in a favorable manner by using conditions suitable for engaging the recording medium with the locking member. The recording medium can be more reliably and reliably locked by the locking member without causing the recording medium to be bent, buckled, bent, or the like, and can be fed satisfactorily. A paper feeding device can be provided.

If the control means changes the drive start timing of the conveying means according to at least one recording condition among the image forming speed, the size of the recording medium, the type of the recording medium, and the environment, The recording medium is conveyed by the conveying means in a favorable manner by using appropriate conditions for engaging the recording medium with the locking member without using the recording medium detecting means. The recording medium can be more reliably and reliably locked by the locking member without causing the recording medium to be bent, buckled, bent, or the like. It is possible to provide a paper feeding device capable of performing the above.

The present invention resides in an image forming apparatus having the paper feeding device according to any one of claims 1 to 12 , and has a paper feeding device that exhibits the above-described effects, and the recording medium is placed on the waist by a seating member. By attaching, the recording medium can be satisfactorily locked by the locking member without causing bending, buckling, bending, etc. of the recording medium, good feeding can be performed, and good image formation An image forming apparatus capable of performing the above can be provided.

  If it is a printing apparatus that performs recording on a recording medium using a plate cylinder, the recording medium is seated with a seating member so that the recording medium can be locked without causing bending, buckling, folding, or the like. It is possible to provide a printing apparatus that is an image forming apparatus that can satisfactorily lock a recording medium by a member, perform good paper feeding to a plate cylinder, and perform good printing. .

  An image can be formed on both sides of the recording medium, and the sheet feeding device is a recording medium on which the image is formed on one side, and then the recording medium on which the image is formed is placed on the other side. If the recording medium is provided as a paper feeding device, the recording medium is satisfactorily engaged by the locking member without causing the recording medium to bend, buckle or bend. Therefore, it is possible to provide an image forming apparatus that can stop feeding, perform good re-feeding, and perform good double-sided image formation.

Since the present invention is a paper feeding method for feeding paper using the paper feeding device according to any one of claims 1 to 12 , the paper feeding device having the above-described effects is used, and a seating member is used. By supporting the recording medium, the recording medium can be satisfactorily locked by the locking member without causing the recording medium to bend, buckle, bend, etc. A paper method can be provided.

Since the present invention is an image forming method for forming an image using the image forming apparatus according to any one of claims 13 to 15 or the paper feeding method according to claim 16, the image exhibiting the above-described effects. By using the forming device or the paper feeding method that exhibits the above-mentioned effects, the recording medium is seated with the seating member, so that the recording medium is satisfactorily secured by the locking member without causing the recording medium to bend, buckle, bend, or the like. Therefore, it is possible to provide an image forming method that can perform good paper feeding and perform good image formation.

  FIG. 1 shows an outline of a thermosensitive digital plate-making integrated duplex printing apparatus to which the present invention is applied. The duplex printing apparatus 1 includes a printing unit 2, a plate making unit 3, a paper feeding unit 4, a plate discharging unit 5, a paper discharging unit 6, an image reading unit 7, an operation panel 103 shown in FIG. The control means 129, the switching means 32, and the temperature detection means and humidity detection means (not shown) for detecting the ambient temperature and humidity inside the duplex printing apparatus 1 are included.

  As shown in FIG. 1, the printing unit 2 is disposed approximately at the center of the apparatus main body 11 that is the main body of the duplex printing apparatus 1. The printing unit 2 is a plate cylinder 12 as a printing drum, an ink supply unit 15, a home position sensor 134 as a photo interrupter, a press roller 13 as a pressing unit, and a refeed unit as a sheet feeding device. The re-feeding means 9, the plate cylinder driving means 121, the press roller contacting / separating mechanism 55 shown in FIG. 7, and a not-shown press roller driving means are provided.

  As shown in FIG. 1, the plate cylinder 12 has a spindle 14 that also serves as an ink supply pipe, a planar stage portion 19a disposed on the outer peripheral surface of the plate cylinder 12, and the stage portion 19a. A clamper 19b for opening and closing and holding the tip of the master 64 on the outer peripheral surface of the plate cylinder 12, and an opening and closing (not shown) for opening and closing the clamper 19b with respect to the stage portion 19a when the plate cylinder 12 is rotated to a predetermined position Means, a pair of end plates (not shown) rotatably supported by the support shaft 14, a dog 133 as a phase timing detection plate attached to the outer surface of the end plate, and wound around the outer peripheral surface of each end plate A porous support plate (not shown) and a mesh screen (not shown) wound around the outer peripheral surface of the porous support plate (not shown) are included.

The plate cylinder driving means 121 has a main motor (not shown) and an encoder (not shown). The encoder generates a rotation pulse signal every time the main motor rotates by a certain angle. The main motor has a variable rotation speed of the plate cylinder 12.
The plate cylinder 12 is rotationally driven by the plate cylinder driving unit 121 under the control of the control unit 129. The plate cylinder 12 is configured to be detachable from the apparatus main body 11. The plate cylinder 12 has a size capable of obtaining a maximum A3 size printed material during single-sided printing.

The ink supply means 15 is disposed inside the plate cylinder 12. The ink supply unit 15 includes a support shaft 14, an ink roller 16, a doctor roller 17, and a driving unit (not shown).
The ink roller 16 is rotatably supported between side plates (not shown) provided in the plate cylinder 12, and its peripheral surface is disposed close to the inner peripheral surface of the plate cylinder 12, and the plate cylinder 12 is driven by driving means. And is rotated in the same direction. 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. The support shaft 14 has a plurality of small holes, and the ink supplied from the support shaft 14 accumulates in a cross-sectional wedge-shaped space formed in the vicinity of the ink roller 16 and the doctor roller 17. A reservoir 18 is formed.

  The home position sensor 134 is attached to the apparatus main body 11 in the vicinity of the periphery of the plate cylinder 12. 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 home position signal as a phase timing signal to the control means 129.

  The press roller 13 is disposed below the plate cylinder 12. The press roller 13 is configured by winding an elastic body such as rubber around a metal core 13 a and is provided so as to extend in the axial direction of the plate cylinder 12. The press roller 13 is composed of a member having ink repellency such as polytetrafluoroethylene resin at least on the peripheral surface thereof. The press roller driving means rotates the press roller 13 at the same peripheral speed as the peripheral speed of the plate cylinder 12.

  Although not shown, the press roller contact / separation mechanism 55 is rotatably supported by a pair of substantially L-shaped arm members that rotatably support both ends of the core portion 13a and the apparatus main body 11. In addition, it has a swing shaft that is attached to a portion in the vicinity of the bent portion of each arm member and integrates each arm member, and a drive means (not shown) that swings each arm member around the swing shaft. The press roller contact / separation mechanism 55 causes the press roller 13 to selectively occupy a separation position that is separated from the plate cylinder 12 and a pressure contact position that is in pressure contact with the plate cylinder 12 by the driving unit being driven by the control unit 129. .

The sheet refeeding means 9 includes a press roller 13, a sheet refeeding guide member 22, a sheet refeeding conveyance unit 25, a cleaning roller 26, a guide plate 27, a guide plate 56, and a cleaning roller driving unit (not shown). have.
As shown in FIG. 1, the refeed guide member 22 is disposed near the right side of the press roller 13. As shown in FIG. 1 or FIG. 2, the refeed guide member 22 includes a plurality of roller-shaped rollers 28, 29, and 30 each having a circumferential surface pressed against the circumferential surface of the press roller 13, and a surface printed. It has a sheet guide plate 31 that is a recording medium and is formed into a curved surface for feeding the sheet PA along the peripheral surface of the press roller 13 for sheet feeding, specifically, for sheet feeding again.

  Each of the rollers 28, 29, and 30 is rotatably supported on the arm member by a support shaft (not shown), and is urged toward the core portion 13a by an urging means (not shown). The rollers 28, 29, and 30 are mounted on the peripheral surface of the press roller 13 at a predetermined interval over almost the entire width of the press roller 13 in the direction perpendicular to the paper surface in FIG. 1.

  The paper guide plate 31 is disposed at a position away from the peripheral surface of the press roller 13 by a predetermined distance that is smaller than the radius of each of the rollers 28, 29, and 30, and both ends thereof are fixed to each arm member. ing. The paper guide plate 31 is formed to have a curved surface centered on the core portion 13 a, and the paper guide plate 31 is configured to bring the peripheral surfaces of the rollers 28, 29, and 30 into contact with the peripheral surface of the press roller 13. A plurality of openings (not shown) are formed.

  The re-feed conveyance unit 25 is disposed on the lower left side of the press roller 13. The refeed transport unit 25 includes a transport unit main body 35, an auxiliary tray 8 as a refeed tray, a refeed registration roller 23, a refeed positioning member 24, a transport unit 21, and an urging unit. 3 as shown in FIG. 3 to FIG. 5, the conveying unit drive motor 122 shown in FIG. 4 or FIG. 7, the solenoid 33 shown in FIG. 7, and the biasing means drive circuit. And a suction-type imparting drive circuit 44, which is a belt-type suction conveyance device.

  The refeed resist roller 23 is disposed below the press roller 13. The re-feeding registration roller 23 has a roller shape and is supported by a support shaft 23a shown in FIGS. The support shaft 23a is pivotally attached to one end of a swing arm 32 shown in FIGS. When the solenoid 33 is operated, the re-feeding registration roller 23 occupies a pressure contact position where the peripheral surface is pressed against the peripheral surface of the press roller 13 with a predetermined pressure contact force as shown in FIG. Then, as shown in FIG. 1, the peripheral surface occupies a separated position away from the peripheral surface of the press roller 13.

  The conveying means 21 has a driving roller 36, a driven roller 37, and an endless belt 38 as a conveying member. The drive roller 36 and the driven roller 37 have a roller shape. The conveying means 21 is arranged in the direction perpendicular to the paper surface in FIG. 1, the left-right direction in FIG. 3, ie, the width direction Y of the paper P, specifically, the paper P indicated by the symbol X in FIG. 1, FIG. In the present embodiment, a plurality, two in the present embodiment, are provided at a predetermined interval in the center in the direction perpendicular to the transport direction.

  As shown in FIG. 3, the drive roller 36 and the driven roller 37 are integral with the drive shaft 36a and the driven shaft 37a, respectively. The drive shaft 36a and the driven shaft 37a are rotatably supported by a bearing (not shown) disposed in the transport unit body 35. A drive gear (not shown) is attached to one end of the drive shaft 36a.

  The transport unit drive motor 122 is a stepping motor, and is provided in the apparatus main body 11. The drive roller 36 is driven to rotate by a drive gear via a drive shaft 36a. The conveyance unit drive motor 122 can change the rotation speed of the endless belt 38 by changing the rotation speed of the drive roller 36 under the control of the control unit 129 and change the conveyance speed of the paper P by the conveyance unit 21. It has become. The transport unit drive motor 122 is preferably a stepping motor, but it is suitable for controlling the rotation of a DC motor or the like with an encoder attached thereto instead of a stepping motor.

  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 is made of a friction resistance member. The endless belt 38 is moved in the transport direction X when the drive roller 36 is rotationally driven by the transport unit drive motor 122 controlled based on the control of the control means 129 so that the paper P is transported in this direction. It has become.

  The transport unit main body 35 is a housing formed so that its upper surface is opened and its width is slightly smaller than the interval between the arm members. The transport unit main body 35 can swing around the drive shaft 36a as each arm member swings when the press roller 13 is brought into and out of contact with the plate cylinder 12 by the press roller contact / separation mechanism 55. It has become.

  As shown in FIG. 2, the adsorption force applying means 39 is integrally attached to the lower surface of the transport unit body 35 with the transport unit body 35. As shown in FIG. 2, the suction force applying means 39 includes a plurality of stop position suction force applying means 41 and 41 as locking biasing means and a plurality of upstream suction force applying means 42 as upstream biasing means. , 42, 43, 43.

  The stop position suction force applying means 41, 41, the upstream suction force applying means 42, 42, and the upstream suction force applying means 43, 43 are in this order in the transport means 21, specifically in the transport direction X. From the downstream side toward the upstream side, it is arranged along the conveyance direction X in a manner including the arrangement position of the conveyance means 21 in the direction Y. The stop position suction force applying means 41, 41 occupy the same position in the transport direction X, and the upstream side suction force applying means 42, 42 and the upstream side suction force applying means 43, 43, respectively. The stop position attracting force applying means 41 and 41 are arranged side by side in the direction Y, that is, the direction perpendicular to the paper surface in FIG. 2 and the up and down direction in FIG. Located in the vicinity.

  As shown in FIG. 2, the stop position suction force applying means 41, 41 and the upstream side suction force applying means 42, 42, 43, 43 are suction fans 41a, 41a, 42a, 42a as biasing means driving means, respectively. 43a, 43a, and ducts 41b, ducts 41b, 42b, 42b, 43b, 43b provided therein with suction fans 41a, 41a, 42a, 42a, 43a, 43a, respectively. The duct 41b, the ducts 41b, 42b, 42b, 43b, 43b are arranged in an independent manner, and a discharge port (not shown) for discharging air is provided at the bottom of the suction fans 41a, 41a, 42a, 42a. , 43a, 43a are formed corresponding to the respective arrangement positions.

  As shown in FIG. 1, FIG. 2, or FIG. 3, the auxiliary tray 8 is integrally provided on the upper surface of the refeed conveyance unit 25. The auxiliary tray 8 temporarily places and stores the surface-printed paper PA. The auxiliary tray 8 has a sheet conveying surface whose upper surface is a recording medium conveying surface as a sheet P loading surface. As shown in FIG. 1 or FIG. 2, the auxiliary tray 8 integrally has two end fences 8a for receiving one end of the surface-printed paper PA at the upstream end in the transport direction X of the paper transport surface. Have.

  As will be described later, during double-sided printing, the surface-printed paper PA, while being guided by the guide plates 27 and 56, falls obliquely downward as shown in FIG. 10, FIG. 12, and FIG. Placed on the tray 8. The transport direction X is included in a direction in which the surface-printed paper PA placed on the auxiliary tray 8 falls and moves toward the auxiliary tray 8 and is parallel to the paper transport surface.

  The auxiliary tray 8 is integrally provided with refeed positioning members 24 and 24 as two locking members for receiving the other end of the front surface printed paper PA at the downstream end in the transport direction X of the paper transport surface. Have. The refeed positioning members 24 and 24 are placed on the auxiliary tray 8 and then engaged with the front end of the front surface printed paper PA which is refeeded toward the plate cylinder 12 to determine the front surface printed paper PA. It is a member for temporarily stopping at a position. The fixed position where the surface-printed paper PA placed on the auxiliary tray 8 engages with the refeed positioning member 24 and temporarily stops is such that the surface-printed paper PA is then directed toward the plate cylinder 12 from here. A refeed position is set for refeeding. The front surface printed sheets PA1 and PA2 shown in FIGS. 2, 4 and 15 respectively occupy the refeeding position.

  As shown in FIG. 3, four holes 23 b are formed in the paper transport surface of the auxiliary tray 8 corresponding to the arrangement positions of the re-feeding registration rollers 23. The respective circumferential surfaces of the rollers 23 are positioned above the sheet conveying surface of the auxiliary tray 8, that is, on the front side of the sheet surface in FIG. 3 by the holes 23 b, and are pressed against the circumferential surface of the press roller 13. Each peripheral surface of 23 is located below the paper transport surface of the auxiliary tray 8, that is, on the back side of the paper surface in FIG. 3, and can occupy a separation position separated from the peripheral surface of the press roller 13. . The re-feeding positioning members 24 and 24 are disposed one by one between the two on the left side in the direction Y and the two on the right side of the four holes 23b.

  Holes 36b, 36b, 37b, and 37b are formed in the paper transport surface of the auxiliary tray 8 corresponding to the positions of the rollers 36 and 37, and the holes 36b, 36b, 37b, and 37b A part of the peripheral surface of each of the rollers 36 and 37 faces, and as shown in FIG. 4, a part of each endless belt 38 is located above the sheet conveying surface.

  A plurality of holes 42c and 43c are formed on both sides of each endless belt 38 on the sheet conveying surface of the auxiliary tray 8 in correspondence with the arrangement positions of the ducts 42b, 42b, 43b and 43b. A plurality of holes 41c are formed in the paper transport surface of the auxiliary tray 8 in correspondence with the arrangement positions of the ducts 41b and 41b. Each of the plurality of holes 41 c is located in the vicinity of the upstream side of the refeed positioning member 24 in the conveyance direction X by the endless belt 38.

  The auxiliary tray 8 is a recording medium detection unit that detects that the front end of the surface-printed paper PA has approached the refeed positioning member 24 in the vicinity of the downstream end in the transport direction X on the paper transport surface. It has a sensor 8c as a printed paper detection member. When the sensor 8c detects the other end of the front-side printed paper PA, the sensor 8c outputs a signal to the control unit 129 described later.

  As shown in FIG. 3, the seating member 20 is a position upstream of the refeed positioning member 24 and downstream of the transport unit 21 in the transport direction X, and applies the sensor 8 c and the stop position adsorption force. As shown in FIG. 5, it is arranged at a position substantially the same as the arrangement position of the means 41 so as to protrude upward from the sheet conveying surface. As shown in FIG. 3 or FIG. 5, the seating member 20 is disposed on the extension line of each transport means 21 in the transport direction X in the direction Y. As shown in FIG. 5, the seating member 20 is seated by curving the paper P in a cross-sectional shape perpendicular to the transport direction X.

When the paper P is transported in the transport direction X until the paper P is engaged with the paper re-feeding positioning member 24 by the transport means 21, the seating member 20 is brought into contact with the paper re-feeding positioning member 24. In order to prevent the occurrence of deflection, the sheet P is mounted in a manner in which the sheet P is curved on a cross section perpendicular to the conveyance direction X. It is desirable that In this embodiment, as will be described later, the sheet P is conveyed by the conveying unit 21 while being adsorbed by the upstream conveying force applying units 42 and 43 and the stop position adsorbing force applying unit 41.

In view of this, in the direction Y, two seating members 20 are disposed on the extension lines of the respective transporting means 21 in the transport direction X, for a total of two, as shown in FIG. By the endless belt 38 and the waisting member 20 disposed, the planar shape portion that is in close contact with the paper conveyance surface on the paper P, and the shape that is engaged with the endless belt 38 and the waisting member 20 and rises in a convex shape from the planar shape portion. The sheet P is bent in a manner that forms a convex portion extending in the transport direction X, and the sheet P is regularly and reliably mounted.

  Note that the sheet P receives a biasing force toward the sheet conveyance surface by the stop position adsorption force applying units 41 and 41 before the sheet refeeding positioning member 24, but the sheet P is upstream in the conveyance direction X of the conveyance unit 21. The curved shape of the direction which protrudes from a paper conveyance surface is given at a comparatively long distance from a side edge part to the seating member 20, and the stop position adsorption force in the conveyance direction X is given to the seating member 20 By occupying the same position as the applying unit 41, the entire position of the sheet P in the direction Y does not stick to the sheet conveying surface before the refeed positioning member 24 by the stop position attracting force applying units 41 and 41. The sheet P has a curved shape as a whole in the transport direction X, and is bent, and even when the leading end abuts against the sheet refeeding positioning member 24, the deflection, buckling, or the like does not occur.

However, if the height of the seating member 20 from the sheet conveyance surface is too high, or if the height of the upper surface of the endless belt 38 from the sheet conveyance surface is too high, the sheet P is lifted and the stop position adsorption force is applied. The adsorbing force on the sheet conveying surface by the means 41, 41 and the upstream adsorbing force applying means 42, 43 is insufficient and the conveying force of the sheet P is insufficient, or the leading edge of the sheet P is rubbed or caught on the press roller 13. As a result, scratches, bends, stains, and conveyance failures occur in the sheet P. Therefore, the height of the seating member 20 from the sheet conveyance surface and the height of the upper surface of the endless belt 38 from the sheet conveyance surface are as follows. The height of the re-feeding positioning member 24 is less than or equal to the height.
Further, in order to prevent the seating member 20 from being caught on the paper P, scratching or bending of the paper P, as shown in FIG. 4, the height of the seating member 20 from the paper transport surface is from the paper transport surface. It is desirable that the height be equal to or less than the height of the upper surface of the endless belt 38. In this embodiment, the height is substantially the same.

  The suction force applying drive circuit 44 is placed on the auxiliary tray 8 with respect to each endless belt 38 by driving the suction fans 41a, 41a, 42a, 42a, 43a, 43a based on the control of the control means 129. A suction force for the applied paper P is applied. The suction force application drive circuit 44 always drives the suction fans 41a and 41a in the same state. However, the suction fans 41a, 42a and 43a can be driven independently.

  That is, the suction force application drive circuit 44 is in an on or stopped state in which each suction fan 41a is simultaneously activated independently of the other suction fans 42a and 43a based on the control of the control means 129. Turn off. Further, the suction force application drive circuit 44 turns on or off the suction fan 43a independently of the other suction fans 41a, 41a, and 42a based on the control of the control unit 129.

  Also, the suction force application drive circuit 44 can turn on or off the suction fan 42a independently of the other suction fans 41a, 41a, and 43a based on the control of the control means 129, and is in the on state. Also, the output can be changed and the suction force can be changed. The output can be selected from a rating of 24V and a lower voltage of 20V.

  When the suction force application drive circuit 44 drives the suction fans 41a, 41a, 42a, 42a, 43a, 43a, air is discharged from the discharge ports of the ducts 41b, ducts 41b, 42b, 42b, 43b, 43b, and the ducts 41b. , A negative pressure is generated inside the ducts 41b, 42b, 42b, 43b, 43b, and air is sucked from the holes 41c, 42c, 43c.

  Accordingly, the holes 42c and 43c cause the surface-printed paper PA to be sucked onto the upper surface of each moving endless belt 38 so that the surface-printed paper PA is sucked onto the endless belt 38 and conveyed. To do. The holes 42c and 43c are formed on the front surface printed paper PA shown in FIG. 10 and the front surface printed paper PA2 shown in FIG. 13 while the front surface printed paper PA is guided by the guide plates 27 and 56 at the time of duplex printing. As described above, the surface-printed paper PA and the auxiliary tray 8 are arranged so that the surface-printed paper PA smoothly falls toward the auxiliary tray 8 when it is dropped obliquely downward and placed on the auxiliary tray 8. By discharging the air in between, the front-side printed paper PA is urged toward the paper transport surface of the auxiliary tray 8.

  Further, each of the holes 41c urges and adsorbs the leading end portion of the surface printed paper PA to the paper conveyance surface of the auxiliary tray 8 when the air is sucked, and the surface printed paper PA is conveyed by the endless belt 38. In this case, the front end of the surface printed paper PA is prevented from getting over the refeed positioning member 24, and is securely engaged with the refeed positioning member 24, and the front surface printed paper PA is conveyed to the refeed position. Surely occupy the re-feeding position.

  Here, the conveyance path of the paper P in the duplex printing apparatus 1 will be described. The conveyance path of the paper P is roughly divided into a paper feed path and a paper discharge path. The paper feed path includes an initial paper feed path until the paper P is transported between the plate cylinder 12 and the press roller 13 from the paper feed tray 67 by the paper feed unit 3, and the paper P by the paper refeed means 9. There is a re-feed path for the (surface-printed paper PA) from between the plate cylinder 12 and the press roller 13 through the auxiliary tray 8 and again between the plate cylinder 12 and the press roller 13. is doing. In the paper discharge path, the paper discharge unit 6 causes the paper P (printed paper PB) to pass from between the plate cylinder 12 and the press roller 13 to a paper discharge tray 86 described later via a paper discharge conveyance unit 85 described later. It is a route conveyed to The initial paper feed path and the paper discharge path carry the paper P during single-sided printing and double-sided printing, while the re-feeding path carries the paper P only during double-sided printing.

Therefore, the paper re-feeding means 9 is a sheet P printed on one side by the plate cylinder 12 during double-sided printing, and then printed on the other side by the plate cylinder 12, that is, a surface-printed sheet PA. Is placed.
Then, the surface-printed paper PA placed on the auxiliary tray 8 is subjected to a reversing action, that is, a switchback action by the refeeding means 9, and is again conveyed between the plate cylinder 12 and the press roller 13 to be printed on both sides. Is done.

  Therefore, as shown in FIG. 8, in double-sided printing, when the first sheet P is fed and the plate cylinder 12 is in the first rotation, the surface of the first sheet P is pressed by the printing pressure of the press roller 13. When the second sheet P is fed and the plate cylinder 12 is rotated a second time, printing is performed on the surface of the second sheet P by the printing pressure of the press roller 13 and the first sheet Printing is performed on the back side of the paper P, whereby double-sided printing is performed on the first sheet. In this way, double-sided printing is performed by continuously printing twice on one sheet P while the plate cylinder 12 rotates twice. Note that the printing of the back surface is not performed at the first rotation of the plate cylinder 12, so the printing pressure of the press roller 13 is released.

  The cleaning roller 26 is located in the vicinity of the press roller 13 and above the refeed conveyance unit 25. The cleaning roller 26 has substantially the same width as the press roller 13. The cleaning roller 26 has at least a surface made of a highly hygroscopic material such as Japanese paper or sponge, and cleans the peripheral surface of the press roller 13.

  The cleaning roller 26 integrally has a core portion (not shown) at the center thereof. The cleaning roller 26 is rotatably supported by fitting a core portion into a slot (not shown) formed in each arm member, and the pressing roller 13 is urged by a biasing means (not shown) provided in the slot. The peripheral surface is always pressed against the peripheral surface of the press roller 13 with a predetermined pressing force.

  The cleaning roller driving means is provided on one arm member. The cleaning roller driving unit drives the cleaning roller 26 to rotate in the same direction as the press roller 13 when the press roller 13 rotates at a peripheral speed of about one-tenth of the peripheral speed of the press roller 13.

  The guide plate 27 is disposed on the left side of the press roller 13 and the cleaning roller 26 in FIG. 1 at a position close to the peripheral surface of the cleaning roller 26 so as to cover the cleaning roller 26. The guide plate 27 is a plate material, and both end portions thereof are fixed to the arm members. The guide plate 27 guides the surface-printed paper PA sent from the printing unit 2 so as not to touch the cleaning roller 26 and toward the auxiliary tray 8.

The guide plate 56 is disposed above the auxiliary tray 8. The guide plate 56 is fixed to the apparatus main body 11. The guide plate 56 guides the surface-printed paper PA to the auxiliary tray 8 while guiding it with the guide plate 27, and one end thereof occupies a position near the upper end of the end fence 8a.
The guide plates 27 and 56 guide the surface-printed paper PA during double-sided printing, and the surface-printed paper PA is guided obliquely downward as shown in FIGS. 10 and 13 while being guided by the guide plates 27 and 56. It falls and is placed on the auxiliary tray 8.

  The switching means 32 shown in FIG. 7 is disposed on the conveyance path of the paper P on the left side of the contact position between the plate cylinder 12 and the press roller 13. The switching unit 32 includes the switching member 10 illustrated in FIG. 1 that switches the conveyance path of the paper P and the solenoid 123 illustrated in FIG. The switching member 10 is made of a plate material having substantially the same width as the plate cylinder 12 and the press roller 13.

  The switching member 10 is fixed at its downstream end in the paper transport direction to a support shaft that is rotatably supported by the apparatus main body 11, and the paper transport direction formed into an acute cross section when the solenoid 123 is actuated. The upstream end is selectively positioned at a first position indicated by a solid line and a second position indicated by a one-dot chain line in FIG.

  When the switching member 10 occupies the first position, the tip of the switching member 10 is close to the peripheral surface of the press roller 13 and at the position where it does not interfere with the clamper 19b on the plate cylinder 12 and occupies the second 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 position, and the switching member 10 is in the second position. Is guided between the guide plate 27 and the guide plate 56 to the auxiliary tray 8.

  The plate making unit 3 is disposed in the upper right part of the apparatus main body 11 in FIG. 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 plate making drive shown in FIG. An urging means (not shown) arranged corresponding to each of the means 124, the tension roller pair 62, and the reverse roller pair 63, a movable master guide plate (not shown), and arranged corresponding to the movable master guide plate. A support member and a solenoid (not shown) and a thermal head driver (not shown) are included.

  The plate making unit 3 performs plate making on the master 64, and as shown in FIG. 9A, the plate making master 64 having a third plate making image 64c that occupies the whole image area as shown in FIG. 9A, or FIG. 9B. As shown in the figure, a divided master-made master 64 having a first plate-making image 64a and a second plate-making image 64b each having substantially the same area and occupying about half of the image area is created. Since printing is performed by directly transferring ink from the master 64 to the paper P, the image on the master 64 is a mirror image as shown in FIG.

  The first platemaking image 64a is formed at a position corresponding to the surface region shown in FIG. 1 when the divided platemaking master 64 is wound on the outer peripheral surface of the plate cylinder 12, and the second platemaking image 64b is divided. When the master 64 after plate making is wound on the outer peripheral surface of the plate cylinder 12, it is formed at a position corresponding to the back surface area shown in FIG. At the time of plate making of the first plate making image 64a and the second plate making image 64b, a predetermined blank portion S shown in FIG. 9B is provided between the first plate making image 64a and the second plate making image 64b. The blank portion S is provided at a position corresponding to the intermediate region shown in FIG. 1 when the master 64 that has been subjected to the plate making process is wound on the outer peripheral surface of the plate cylinder 12.

The master holding member 57 is provided on each pair of side plates (not shown) of the plate-making part 3, and a core of a master roll 64a formed by winding a master 64 in which a thermoplastic resin film and a porous support are bonded together into a roll shape. Both ends of the portion 64b are supported rotatably and detachably.
The plate making drive means 124 has a stepping motor (not shown).

The platen roller 58 is disposed on the left side of the master holding member 57 in FIG. The platen roller 58 is rotatably supported on a side plate (not shown) of the plate making unit 3 and is rotationally driven by the plate making drive unit 124.
The thermal head 59 is disposed below the platen roller 58. The thermal head 59 is attached to a side plate (not shown) of the plate-making unit 3, and its heating element surface is pressed against the platen roller 58 by a biasing force of a biasing means (not shown). The thermal head 59 has a large number of heating elements.
The thermal head driver selectively heats the heating elements of the thermal head 59 in a state where the thermal head 59 is in contact with the thermoplastic resin film surface of the master 64, whereby the thermal head 59 is thermally melted with respect to the master 64. Perform perforating plate making.

  The cutting means 60 is disposed on the left side of the platen roller 58 and the thermal head 59. The cutting means 60 has a fixed blade 60a fixed to a frame (not shown) of the plate making unit 3 and a movable blade 60b supported by the fixed blade 60a so as to be movable. The cutting means 60 has a well-known configuration for cutting the master 64 when the movable blade 60b rotates relative to the fixed blade 60a.

  The master stock unit 61 is disposed below the cutting means 60 on the downstream side in the master conveyance direction. The master stock unit 61 is a space for temporarily storing the divided master-making master 64 or the normal master-making master 64. The master stock portion 61 is a space in which the inside is partitioned by a plurality of plate members and the portion excluding the upper portion is hermetically sealed, and a suction fan (not shown) is disposed at the innermost portion. By operating the suction fan, a negative pressure is generated inside the master stock unit 61, and the master 64 that has been transported and made by plate making is stored toward the innermost part of the master stock unit 61.

  The tension roller pair 62 is disposed at a portion between the cutting means 60 and the master stock portion 61. The tension roller pair 62 includes a driving roller 62a and a driven roller 62b that are rotatably supported by a side plate (not shown) of the plate making unit 3, and a torque limiter (not shown) disposed inside the driving roller 62a. . The urging means urges the driven roller 62b toward the driving roller 62a, and presses the peripheral surface of the driven roller 62b against the peripheral surface of the driving roller 62a.

  The tension roller pair 62 conveys the master 64 while sandwiching the master 64 with the driven roller 62b when the driving roller 62a is rotationally driven by the plate-making driving means 124. The drive roller 62a is set to have a peripheral speed slightly higher than the peripheral speed of the platen roller 58, and a predetermined tension is applied to the master 64 between the platen roller 58 and the tension roller pair 62 by a torque limiter. It comes to grant.

  The reverse roller pair 63 is disposed downstream of the master stock unit 61 in the master conveyance direction. The reversing roller pair 63 includes a driving roller 63a and a driven roller 63b that are rotatably supported by a side plate (not shown) of the plate making unit 3, and a one-way clutch (not shown) disposed inside the driving roller 63a. . The urging means urges the driven roller 63b toward the driving roller 63a, and presses the peripheral surface of the driven roller 63b against the peripheral surface of the driving roller 63a. The reverse roller pair 63 conveys the master 64 while sandwiching the master 64 with the driven roller 63b when the driving roller 63a is rotationally driven by the plate-making driving means 124.

  The movable master guide plate is disposed at a portion between the tension roller pair 62 and the reverse roller pair 63. The movable master guide plate is swingably supported by the support member, and the upper surface of the movable master guide plate constitutes the conveying path of the master 64 by the solenoid, and the retracted position that does not prevent the master 64 from entering the master stock unit 61. Selectively positioned.

The paper feeding unit 4 is disposed below the plate making unit 3. The paper feed unit 4 includes a paper feed tray 67, a paper size detection sensor 73 as a paper size detection means, a paper feed roller 68, a separation roller 69, a separation pad 70, a timing belt 69a, and a registration roller pair 71. 7, paper feed guide plates 136, 137, paper feed drive means 125 shown in FIG. 7, biasing means (not shown) provided corresponding to separation pad 70, and resist roller pair 71. Driving force transmission means (not shown).
The paper feed driving means 125 includes lifting / lowering means. The driving force transmission means includes a gear, a cam and the like.

  The paper feed tray 67 is supported by the apparatus main body 11 so as to be movable up and down, and is moved up and down by the paper feed driving means 125. The paper feed tray 67 has a size that allows A3 size paper P to be placed vertically. The paper feed tray 67 has a pair of side fences 72 supported on a top surface thereof by a rail member (not shown) so as to be movable in a paper width direction perpendicular to the paper transport direction. Is possible.

A plurality of paper size detection sensors 73 are arranged on the free end side of the paper feed tray 67, detect the size of the stacked paper P, and send a signal related to the size of the paper P to the control means 129. ing.
The paper feed roller 68 is disposed above the paper feed tray 67. 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 tray 67 is lifted by the elevating means, the paper feed tray 68 is pressed with a predetermined pressure. The uppermost sheet P on 67 is pressed. The paper feed roller 68 is rotationally driven by the paper feed driving means 125. The paper feed roller 68 has a high frictional resistance member on the surface.

  The separation roller 69 and the separation pad 70 are disposed on the left side of the paper feed roller 68 in FIG. The separation roller 69 and the separation pad 70 each have a high friction resistance member on the surface. The timing belt 69 a connects the separation roller 69 to the paper feed roller 68, and the separation roller 69 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 the urging force of the urging means.

  The registration roller pair 71 is disposed on the left side of the separation roller 69 and the separation pad 70 in FIG. The registration roller pair 71 includes a driving roller 71a and a driven roller 71b, and the driving roller 71a is synchronized with the plate cylinder 12 by transmitting the rotational driving force from the plate cylinder driving unit 121 by the driving force transmitting unit. The paper P is fed to the printing unit 2 at a predetermined timing by the driven roller 71b that is rotated at the predetermined timing and is in pressure contact with the driving roller 71a.

  The paper feed guide plates 136 and 137 are disposed upstream and downstream of the registration roller pair 71 in the paper conveyance direction. The paper feed guide plates 136 and 137 are respectively fixed between side plates (not shown) of the apparatus main body 11. The paper feed guide plates 136 and 137 are members that guide the conveyance of the paper P fed from the paper feed unit 4 to the printing unit 2.

The plate discharging unit 5 is disposed on the upper left side of the printing unit 2 in FIG. The plate discharging unit 5 includes an upper plate discharging member 74, a lower plate discharging member 75, a plate discharging box 76, a compression plate 77, a plate discharging driving means 126 shown in FIG. 7, and a driving force transmitting means (not shown).
The plate removal driving means 126 has a moving means and an elevating means (not shown). The driving force transmission means includes a gear, a belt, and the like.

The upper plate removal member 74 includes a driving roller 78, a driven roller 79, and an endless belt 80. The lower plate removal member 75 includes a driving roller 81, a driven roller 82, and an endless belt 83.
The plate discharge driving means 126 rotates the driving roller 78 in the clockwise direction in the drawing to move the endless belt 80 in the arrow direction in FIG. 1 and drives the driving force to the driving roller 78 via the driving force transmitting means. The drive roller 81 is driven to rotate in the counterclockwise direction in the figure, and the endless belt 83 is moved in the arrow direction in FIG.

The moving means selectively occupies the lower discharge plate member 75 at a position where the endless belt 83 is separated from the outer peripheral surface of the plate cylinder 12 and a position where the endless belt 83 contacts the outer peripheral surface of the plate cylinder 12 as shown in the figure. Let
The plate removal box 76 is a member that stores the used master 64 therein. The plate removal box 76 is detachably attached to the apparatus main body 11.
The compression plate 77 is a member that pushes the used master 64 carried by the upper plate removal member 74 and the lower plate removal member 75 into the plate release box 76. The compression plate 77 is supported by the apparatus main body 11 so as to be movable up and down, and is moved up and down by an elevating means.

  The paper discharge unit 6 is disposed below the plate discharge unit 5 in FIG. The paper discharge unit 6 includes a peeling claw 84, an air knife device 40, a paper discharge conveyance unit 85 as a paper discharge conveyance means, a paper discharge tray 86, a paper discharge drive means 127 shown in FIG. It has a swinging means and a driving force transmitting means (not shown).

  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 peeling claw 84 is swung by claw rocking means, and the tip thereof is located near the peripheral surface of the plate cylinder 12 and the tip thereof is the outer periphery of the plate cylinder 12 in order to avoid obstacles such as the clamper 19b. Selectively occupying a position away from the surface. The driving force transmitting means transmits the driving force from the plate cylinder driving means 121 to the claw swinging means, and swings the peeling claw 84 in synchronization with the rotation of the plate cylinder 12.

  The air knife device 40 is disposed in an integrated manner on the bottom surface of the plate discharging unit 5. The air knife device 40 drives the fan 40a by controlling the fan 40a, the duct 40b for blowing the air generated by the fan 40a toward the plate cylinder 1 in a thin layer, and the control means 129. FIG. Fan driving means 40c shown in FIG.

  The printed paper PB is stuck to the master 64 on the plate cylinder 12 due to the viscosity of the ink, and the printed paper PB on which a solid image is printed in particular causes jamming due to so-called roll-up. However, the printed paper PB can be peeled off from the master 64 by inserting the leading end of the paper discharge claw 84 between the master 64 on the plate cylinder 12 and the printed paper PB. Even when the viscosity is high and peeling by the paper discharge claw 84 alone is not good, the air knife device 40 inserts a thin layer of air between the master 64 and the printed paper PB, thereby discharging the paper. The peeling by the nail 84 is assisted and the peeling is performed well.

The paper discharge conveyance unit 85 is disposed below the peeling claw 84 and to the left of the switching member 10 in FIG. The paper discharge conveyance unit 85 includes a driving roller 87, a driven roller 88, an endless belt 89, a suction fan 90, and a unit side plate (not shown).
The drive roller 87 has a roller shape, and a plurality of drive rollers 87 are attached to a support shaft (not shown) rotatably supported by the unit side plate at a predetermined interval in a direction perpendicular to the paper surface of FIG. 1 or FIG. The driven roller 88 has a roller shape, and a plurality of driven rollers 88 are provided at equal intervals with each drive roller 87 on a support shaft (not shown) rotatably supported on the unit side plate. An endless belt 89 is wound around each driving roller 87 and each corresponding driven roller 88 corresponding thereto.

The paper discharge driving unit 127 integrally rotates each drive roller 87, rotates each endless belt 89, and rotates each driven roller 88.
The 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 printed paper PB on 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.
The paper discharge tray 86 is a member on which the printed paper PB conveyed by the paper discharge conveyance unit 85 is stacked. The paper discharge tray 86 has, on its upper surface, one end fence 91 that is movable in the transport direction of the stacked sheets and a pair of side fences 92 that are movable in the width direction of the stacked sheets.

  The 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, and reflection mirrors 95, 96, 97 for scanning and reading a document image. 98 and a fluorescent lamp 99, a lens 100 for focusing light from a scanned document image, an image sensor 101 such as a CCD for receiving the focused light, and a plurality of document size detection sensors 102 for detecting the size of the document. The image memory 135 for storing the read image data and the reading drive means 128 shown in FIG. 7 are provided. The reading drive unit 128 performs a document image reading operation. The image data recorded in the image memory 135 is digital data, and may be image data created by an external device such as a computer connected to a network in addition to image data relating to a document read by the image reading unit 7. .

  The operation panel 103 is disposed on the upper front surface of the apparatus main body 11. As shown in FIG. 6, the operation panel 103 has a plate making start key 104, a printing start key 105, a trial printing key 106, a continuous key 107, a clear / stop key 108, a numeric keypad 109, an enter on the upper surface thereof. A key 110, a program key 111, a mode clear key 112, a printing speed setting key 113, a four-direction key 114, a paper size setting key 115 as a paper size detecting means, and a paper thickness setting as a paper thickness detecting means. A key 116, a double-sided printing key 117, a single-sided printing key 118, a display device 119 composed of a 7-segment LED, and a display device 120 composed of an LCD are included.

A plate making start key 104 is pressed when the duplex printing apparatus 1 performs a plate making operation. When the plate making start key 104 is pressed, the plate making operation is performed after the plate discharging operation and the document reading operation are performed. Thereafter, the plate making operation is performed, and the duplex printing apparatus 1 enters the print standby state.
A print start key 105 is pressed when causing the duplex printing apparatus 1 to perform a printing operation. When the print start key 105 is pressed after the duplex printing apparatus 1 enters a print standby state and various printing conditions are set, a printing operation is performed.

  The trial printing key 106 is pressed when causing the duplex printing apparatus 1 to perform trial printing. When the trial printing key 106 is pressed after various conditions are set, only one sheet is printed. The continuous key 107 is pressed before pressing the plate making start key 104 when performing the plate making operation and the printing operation continuously. When the plate making start key 104 is pressed after the printing conditions are input after the continuous key 107 is pressed, the printing operation is performed following the plate discharging operation, the document reading operation, and the plate making operation.

  The clear / stop key 108 is pressed when the operation of the duplex printing apparatus 1 is stopped or when the number is cleared. The numeric keypad 109 is used for numerical input. The enter key 110 is pressed when setting numerical values or the like during various settings. The program key 111 is pressed when registering or calling a frequently performed operation. The mode clear key 112 is pressed to clear various modes and return to the initial state.

  The printing speed setting key 113 is pressed when setting the printing speed prior to the printing operation. The print speed setting key 113 sets a slower print speed when a darker image is desired or when the ambient temperature is low, and a faster print speed is desired when a thinner image is desired or when the ambient temperature is high. It is to set. The four-direction key 114 has an upper key 114a, a lower key 114b, a left key 114c, and a right key 114d. The four-way key 114 is pressed when adjusting the image position at the time of image editing or when selecting a numerical value or an item at various settings.

  A paper size setting key 115 is pressed when an arbitrary paper size is input. The paper size input with the paper size setting key 115 has priority over the paper size detected by the paper size detection sensor 73. The paper thickness setting key 116 is pressed when inputting the thickness of the paper P prior to duplex printing. The paper thickness setting key 116 is configured to select one of three types of “plain paper”, “thin paper”, and “thick paper”. Accordingly, the paper thickness setting key 116 serves as a paper thickness detecting means for detecting the thickness of the paper P used for printing. The paper thickness setting key 116 sends a signal regarding the thickness of the input paper P to the control means.

  The duplex printing key 117 is pressed before the press-making start key 104 is pressed when the duplex printing apparatus 1 performs the duplex printing operation. When the duplex printing key 117 is pressed, the LED 117a arranged in the vicinity of the key is turned on to indicate to the operator that the duplex printing mode is in effect. Further, when the duplex printing key 117 is pressed, the input of the plate making start key 104 is rejected only after the thickness of the paper P to be used is input by the paper thickness setting key 116.

  Similar to the double-sided printing key 117, the single-sided printing key 118 is pressed before the start key 104 is pressed when the double-sided printing apparatus 1 performs a single-sided printing operation. When the single-sided printing key 118 is pressed, the LED 118a arranged in the vicinity thereof is lit to indicate to the operator that the single-sided printing mode is in effect. In the duplex printing apparatus 1, the LED 118a is lit in the initial state, and the single-sided printing mode is set.

A display device 119 composed of a 7-segment LED mainly displays numbers such as the number of printed sheets.
The display device 120 is composed of an LCD. The display device 120 has a hierarchical display structure. By pressing selection setting keys 120a, 120b, 120c, and 120d provided below the display device 120, changes to various modes such as zooming and position adjustment, and various modes are possible. The mode can be set. Further, the display device 120 displays the state of the duplex printing apparatus 1 such as “can be made / printed” as shown in the figure, an alarm such as a plate making or discharge jam, a paper feed or paper discharge jam, and a printing paper. In addition, a supply instruction of a supply such as a master and ink is also displayed.

As shown in FIG. 7, the control means 129 is a known microcomputer having a CPU 130, a ROM 131, and a RAM 132. The control means 129 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 discharge plate. Drive unit provided in the image forming unit 5, the paper discharge unit 6, and the image reading unit 7, the display operation on the display devices 119 and 120, the operation of the press roller contact / separation mechanism 55 provided in the printing unit, and the refeed unit 9 The operation of the solenoid 33, the attracting force application drive circuit 44 and the conveying member drive motor 122 provided in the above, the operation of the solenoid 123 for operating the switching member 10, and the like are controlled, and the operation of the entire duplex printing apparatus 1 is controlled.

  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 the home position signal from the home position sensor 134 and the signal from the encoder. Specifically, the rotational phase position of the plate cylinder 12, in other words, the rotational phase timing is detected and recognized in real time using the rotational pulse signal from the encoder correlated with the rotation of the main motor. Thereby, the control means 129 can generate a phase timing signal at an arbitrary phase angle of the plate cylinder 12.

  The control unit 129 determines that a jam has occurred in the refeed unit 9 when the sensor 8c continues to detect the sheet P even after a predetermined time has passed since the sensor 8c started to detect the sheet P. If the paper P is not detected yet after a predetermined time from the timing when the sensor 8c should start detecting the paper P, the refeeding means 9 in the transport path of the paper P is displayed on the display device 120. It is determined that a jam has occurred on the upstream side of the sheet conveyance direction, and a message to that effect is displayed. In this respect, the sensor 8c has a function as jam detecting means.

  The control unit 129 controls the operation of the transport unit drive motor 122 and rotates the drive roller 36 to rotate the endless belt 38 and controls the suction force applying drive circuit 44 together with the suction fan 41a. , 41a, 42a, 43a are controlled so that the paper feed P placed on the auxiliary tray 8 by the refeeding means 9 is transported well.

  In other words, the control means 129 controls the suction force application driving circuit 44 so that the conveyance of the paper P placed on the auxiliary tray 8 and transported by the endless belt 38 is improved. The suction fans 41a, 41a, 42a, and 43a are driven to control the magnitude of the suction force of the endless belt 38 on the paper P placed on the auxiliary tray 8.

  Specifically, the suction force of the suction fans 41a, 42a, and 43a is set so that when the other end of the surface-printed paper PA comes into contact with the refeed positioning member 24, the surface-printed paper PA, each endless belt 38, Is set to a strength that does not cause buckling or deflection of the paper P. The transportability of the paper P by the endless belt 38 depends not only on the suction force of the suction fans 41a, 42a, and 43a but also on the frictional resistance force of the endless belt 38. This frictional force also causes the buckling and deflection of the paper P. It is said that it is strong enough not to occur. Therefore, the suction force of the suction fans 41a, 42a, and 43a and the frictional resistance force of the endless belt 38 are determined by the surface printed paper PA when the other end of the surface printed paper PA comes into contact with the refeed positioning member 24. Between the endless belts 38 and the endless belts 38, and the balance is set so as to prevent the sheet P from buckling or bending.

  However, depending on the recording conditions including at least one of the image forming speed, that is, the printing speed, the size, the type, and the environment of the paper P, the leading edge of the paper P may be re-feeding positioning member 24 depending on such a configuration. When the sheet abuts, the sheet P may be bent or buckled. That is, in the case where the paper P is, for example, high-quality 55K paper, which has a stiffness that is about the same as or larger than copy paper, such a configuration can prevent such a problem of the paper P. Such a problem can be prevented when a paper having a strong stiffness is used as the paper P. For example, a paper P having a relatively weak stiffness such as a medium-quality paper or an additional paper is used. In such a case, particularly when such a low-stiff sheet P is transported in a direction perpendicular to the direction of its eyes and stopped, such a problem may occur. Further, when the driving of the transport unit 21 is continued even after the leading edge of the paper P comes into contact with the refeed positioning member 24, the same problem occurs.

Therefore, the control unit 129 controls the conveyance unit drive motor 122 to control the conveyance unit 21 in accordance with printing conditions and the like, and controls the conveyance unit drive motor 122 to prevent such a problem. ing.
Specifically, among the printing conditions, regarding the printing speed, the control unit 129 changes the conveyance speed of the paper P by the conveyance unit 21 in accordance with the printing speed set by the printing speed setting key 113. . That is, as the printing speed increases, the conveying speed of the paper P by the conveying means 21 is increased, and as the printing speed decreases, the conveying speed of the paper P by the conveying means 21 is decreased.

  Among the printing conditions, the size of the paper P is detected by the paper size setting key 115 when the size of the paper P detected by the paper size detection sensor 73 or the size of the paper P is input by the paper size setting key 115. The control means 129 changes the transport speed of the paper P by the transport means 21 in accordance with the size of the paper P. That is, as the size of the paper P becomes larger, the stiffness becomes weaker and deflection or the like tends to occur. Therefore, the conveyance speed of the paper P by the conveying means 21 is slowed, and as the size of the paper P becomes smaller, the stiffness becomes stronger. Since it becomes difficult, the conveyance speed of the paper P by the conveyance means 21 is increased.

  Among the printing conditions, for the type of paper P, the control unit 129 changes the transport speed of the paper P by the transport unit 21 according to the type of the paper P set by the paper thickness setting key 116. That is, as the thickness of the paper P decreases, deflection or the like is likely to occur. For example, when “thin paper” is set by the paper thickness setting key 116, the transport speed of the paper P by the transport means 21 is decreased, and the thickness of the paper P is reduced. For example, when “plain paper” is set by the paper thickness setting key 116, the conveyance speed of the paper P by the conveyance means 21 is made faster than that of “thin paper”.

Among the printing conditions, regarding the environment, the control unit 129 changes the conveyance speed of the paper P by the conveyance unit 21 based on temperature and humidity.
Specifically, with respect to temperature, as the temperature increases, the viscosity of the ink decreases, the printing speed is increased to prevent the printing density from increasing, and as the temperature decreases, the ink increases. The printing speed tends to be slowed to prevent the printing density from becoming low and the printing density from becoming low. Therefore, as the temperature detected by the temperature detecting means increases, The conveyance speed is decreased, and the conveyance speed of the paper P by the conveyance means 21 is increased as the temperature detected by the temperature detection means increases.

  Regarding the humidity, as the humidity increases, the stiffness of the paper P becomes weaker and bending or the like is likely to occur. Therefore, the conveyance speed of the paper P by the conveyance means 21 is decreased as the humidity detected by the humidity degree detection means increases. Since the stiffness becomes stronger as the humidity is lowered, it becomes difficult to cause deflection and the like. Therefore, the conveyance speed of the paper P by the conveyance unit 21 is increased as the humidity detected by the humidity degree detection unit is lowered. When the humidity increases, the viscosity of the ink decreases and the printing density increases. When the humidity decreases, the viscosity of the ink increases and the printing density decreases. The conveyance speed of the paper P by the conveyance means 21 is controlled in the same manner as the control relating to the temperature.

  The control means 129 determines the drive stop timing of the transport unit drive motor 122, that is, when the drive is stopped. The front end of the paper P is a predetermined point upstream of the refeed positioning member 24 in the transport direction X, specifically, the sensor 8c. A predetermined time has passed since the passage. The time when the predetermined time elapses is immediately after the leading edge of the paper P comes into contact with the refeed positioning member 24. This is to prevent problems such as deflection of the paper P that may occur when the transport unit 21 continues to be driven even after the leading edge of the paper P contacts the re-feed positioning member 24.

  As described above, since the control unit 129 controls the conveyance speed of the paper P by the conveyance unit 21 according to the printing conditions, the refeeding positioning is performed from the time when the leading edge of the paper P passes the sensor 8c according to the printing conditions. The time required to contact the member 24 is also different. Therefore, the control unit 129 immediately after the leading edge of the paper P contacts the refeed positioning member 24 according to the transport speed of the paper P determined as described above according to the printing conditions. The time from when the sensor 8c detects the leading edge of the paper P until the driving of the transport unit driving motor 122 is stopped is determined so as to stop the driving. As described above, the control unit 129 determines when the driving of the transport unit 21 is stopped based on the detection timing of the paper P by the sensor 8c.

When the driving of the transport unit 21 is stopped, the timing is as early as possible after the leading edge of the paper P abuts against the refeed positioning member 24 so that the paper P is not bent.
The transport unit 21 is configured such that the rotation of the endless belt 38 is stopped simultaneously with the energization of the transport unit drive motor 122, and the sheet P is also attracted to the sheet transport surface by the adhesion applying unit 39. Therefore, after the drive stop control of the transport unit 21, the paper P does not move in the transport direction X due to the inertia of the endless belt 38 or the paper P, and an unintentional hit against the refeed positioning member 24 does not occur. Therefore, the deflection of the paper P is well prevented.

  The time for which the transport unit drive motor 122 should be rotated for one sheet P so that the sheet P hits the refeed positioning member 24 varies depending on the transport speed of the sheet P by the transport unit 21 and the size of the sheet P itself. If the transport speed of the paper P and the size of the paper P are the same, the time for which the transport unit drive motor 122 should be rotated may be constant. Therefore, as another control mode, the control unit 129 conveys the paper P toward the refeed positioning member 24 according to the operation timing of the plate cylinder driving unit 121 without using the sensor 8c. 21 drive can be controlled.

  Specifically, the control unit 129 determines the driving speed of the conveying unit 21 and the time for driving the conveying unit 21 using the same in the same manner as described above according to the printing conditions. In addition to the operation timing, the driving start timing of the transport unit 21 can be changed in consideration of the timing at which the paper P falls.

  In this case, since the drive time of the transport unit 21 is uniquely determined, changing the drive start timing of the transport unit 21 is equivalent to changing the drive stop timing of the transport unit 21, but as described above, The drive stop timing of the means 21 is to prevent problems such as deflection of the paper P that occur when the transport means 21 continues to be driven even after the leading edge of the paper P abuts against the refeed positioning member 24. Since the leading edge of the paper P is immediately after contacting the refeed positioning member 24, the drive start timing of the transport unit 21 is substantially determined based on the drive stop timing of the transport unit 21. It becomes.

  As will be described later, when the paper re-feeding registration roller 23 is swung from the separation position to the pressure contact position, the leading edge of the paper P that has been stopped in contact with the paper re-feeding positioning member 24 is pushed up. Thus, the engagement with the refeeding positioning member 24 is released and the refeeding is performed toward the plate cylinder 12 by contacting the circumferential surface of the press roller 13. It is not necessary to drive to feed out the paper P that has occupied the position.

  As described above, regardless of whether the sensor 8c is used or not, since the driving stop time of the conveying unit 21 is determined according to the printing conditions, the printing conditions are substantially set even when the driving of the conveying unit 21 is started. It may be said that it is determined accordingly. Since the time when the driving of the conveying unit 21 is stopped is set as early as possible so that the deflection of the sheet P does not occur, the deflection of the sheet P does not occur when the driving of the conveying unit 21 is started. It can be said that the timing is as late as possible.

  However, in determining the transport speed of the paper P by the transport means 21 in accordance with the printing conditions described above, the paper P does not interfere with the print cycle and the paper P reliably contacts the refeed positioning member 24. The conveyance speed of the paper P by the conveyance means 21 is made as slow as possible so that the deflection of the paper P does not occur within the range.

  Data relating to the driving speed of the conveying means 21, the driving start time, the driving continuation time, the driving stop time, the timing at which the paper P drops, and the like corresponding to various conditions for performing the above-described control in the control means 129 are stored in the ROM 131. When the sensor 8c is not used, the above-described control is performed in consideration of the operation timing of the plate cylinder driving means 121.

  The data recorded in the ROM 131 associates the various conditions described above with the number of energized pulses to the transport unit drive motor 122 after the sensor 8c detects the paper P, or the operation timing of the plate cylinder drive unit 121. However, instead of the number of energized pulses, other equivalent data may be recorded in a table.

  The control means 129 also controls the suction fan 41a to drive the suction fans 41a, 41a, 42a, 42a, 43a, 43a during double-sided printing, and guides the auxiliary tray 8 by the guide plates 27, 56. Control is performed so that the surface-printed paper PA is placed on the auxiliary tray 8 in an excellent manner.

  That is, the control unit 129 controls the suction force application drive circuit 44 so that the surface-printed paper P is placed on the auxiliary tray 8 in a favorable manner, so that the suction fans 41a, 41a, 42a, 42a, 43a, 43a are controlled. The driving is controlled, and the urging force of the surface printed paper PA to the auxiliary tray 8 by the suction fans 41a, 41a, 42a, 42a, 43a, 43a, that is, the magnitude of the suction force is controlled.

Specifically, the control means 129 is
Whether paper P (surface-printed paper PA) is already placed on the auxiliary tray 8;
The thickness of the paper P placed on the auxiliary tray 8,
The suction force application drive circuit 44 is driven according to a predetermined condition of the size of the paper P placed on the auxiliary tray 8, and the suction fan 41a, 41a, 42a, 42a, 43a, 43a is moved to the auxiliary tray 8 The urging force, that is, the magnitude of the suction force of the front surface printed paper PA is controlled. Each will be described below.

Control based on whether or not the paper P is already placed on the auxiliary tray 8 This control causes the leading edge of the paper P to be rounded and jammed when the paper P is placed on the auxiliary tray 8. This is done to prevent this.

  That is, even when the paper P is not placed on the auxiliary tray 8, the suction fans 41 a, 41 a, 42 a, 42 a, 43 a, 43 a are used under the same conditions as when the paper P is placed on the auxiliary tray 8. In this case, the action that the paper P receives, that is, the action that the suction fans 41a, 41a, 42a, 42a, 43a, and 43a urge the paper P toward the auxiliary tray 8 is greatly affected. When P falls quickly and is placed on the auxiliary tray 8, the leading edge of the paper P is rounded, causing jamming. These are particularly likely to occur with weakly crumpled paper. In order to prevent this, the control means 129 has the suction fans 41 a, 41 a, and 4 in the state where the paper P is not placed on the auxiliary tray 8 than in the state where the paper P is placed on the auxiliary tray 8. The suction force applying drive circuit 44 is controlled so that the biasing force of the surface-printed paper PA to the auxiliary tray 8 by 42a, 42a, 43a, 43a is reduced.

  Specifically, the control unit 129 detects whether or not the paper P has already been placed on the auxiliary tray 8 according to whether duplex printing is being performed or how many times the plate cylinder 12 is rotating. When double-sided printing is performed and the plate cylinder 12 has made one or more revolutions, it is detected that the paper P has already been stacked on the auxiliary tray 8, and when this is detected, the suction force applying drive circuit 44 is detected. Thus, the upstream fan 43a in the transport direction X is driven.

  However, at the time of duplex printing, when the plate cylinder 12 has not yet rotated once, it is detected that the paper P is not yet stacked on the auxiliary tray 8, and when this is detected, the suction force application drive circuit 44 is detected. Thus, the driving of the upstream fan 43a in the transport direction X is stopped. Thereby, the fall of the paper P becomes the same as the case where the paper P has already been placed on the auxiliary tray 8, and when the paper P is placed on the auxiliary tray 8, the leading edge of the paper P will not be rounded.

The condition that the fan 43a is stopped is obtained as a result of an experiment using the duplex printing apparatus 1. For example, when the fan 42a is stopped as well as the fan 43a, printing is performed at a rate of 120 sheets / minute. In this case, the falling speed of the trailing edge of the paper P is reduced, the trailing edge of the paper P is caught by the guide plate 27, and the placement on the auxiliary tray 8 may not be performed smoothly. Therefore, it is considered that the fan to be stopped is preferably disposed at an upstream portion in the conveyance direction P by the endless belt 38.
However, such conditions can be changed as appropriate so that the leading edge of the paper P is not rounded, etc., and the number and combination of fans to be stopped, the fan output can be changed, or the fan changing the output can be changed. The number, the combination can be changed, or these can be combined.

Control based on the thickness of the paper P placed on the auxiliary tray 8 This control is performed when the paper P is conveyed on the auxiliary tray 8 by the endless belt 38 and abuts against the refeed positioning member 24. This is to prevent the paper P from being damaged or broken due to a strong impact.

  That is, when the suction fans 41a, 41a, 42a, 42a, 43a, and 43a are driven under the same conditions regardless of the thickness of the paper P, when the paper P is thicker and thinner, it is thinner. However, since the sheet P is easily deformed along the shape of the endless belt 38 and the auxiliary tray 8 and easily adheres to the endless belt 38, the sheet P is assisted by the biasing action of the suction fans 41a, 41a, 42a, 42a, 43a, 43a. After being stacked on the tray 8, when the endless belt 38 is transported toward the refeed positioning member 24, the thin paper P is in a state of being in close contact with the endless belt 38, and is unlikely to slip and has a large transport force. When the sheet P is conveyed and is brought into contact with the sheet re-feeding positioning member 24, it receives a strong impact, and the sheet P is scratched or broken.

  For example, medium-quality paper and high-quality paper are more susceptible to the action of the adhesive force imparting means 39 because the medium-quality paper is weaker, and abuts against the re-feed positioning member 24 in a state of being in close contact with the endless belt 38. It is more likely to be damaged or broken than fine paper. In order to prevent this, the control means 129 uses the suction fan 41a, 41a, 42a, 42a, 43a, 43a on the surface of the endless belt 38 when the paper P is thin or thin. The suction force application drive circuit 44 is controlled so that the urging force of the printed paper PA is reduced.

  Specifically, the control unit 129 is a double-sided printing, and the paper P used for printing detected by the paper thickness setting key 116, that is, the paper P placed on the auxiliary tray 8 is thin. Occasionally, the energizing voltage applied to the downstream fan 42a in the transport direction X is set to 20V, which is lower than the rated 24V, and the output is reduced as shown in FIGS. Let As a result, the conveyance force of the paper P by the endless belt 38 becomes the same as that of plain paper and thick paper, and the paper P does not receive a strong impact when hitting the refeed positioning member 24, and the paper P is scratched or broken. There is no.

  The condition that the output of the fan 42a is reduced is obtained as a result of an experiment using the double-sided printing apparatus 1. According to this result, the energization voltage to the fan 42a is preferably 16V to 20V. I understood that. If it is greater than 20 V, the paper P may be scratched or broken. If it is less than 16 V, the conveyance force of the paper P by the endless belt 38 will be weak, or the speed at which the paper P will fall will be reduced to the auxiliary tray 8. This is because there was a case where the placement of was not performed smoothly. Since the energization voltage to the fan 42a is preferably 16V to 20V, it is not limited to 20V, and can be lowered in the range of 16V to 20V.

  Further, if the energization voltage of the fan 43a as well as the fan 42a is reduced, the conveyance force of the paper P by the endless belt 38 becomes weak, or the falling speed of the paper P becomes small and the paper P is placed on the auxiliary tray 8. May not go smoothly. Therefore, it is considered that the fan for reducing the output is preferably disposed in the downstream portion in the transport direction X.

  However, such conditions can be changed as appropriate so as not to damage the leading edge of the paper P. The number and combination of fans that lower the output can be changed, the fan output can be stopped, or the fan can be stopped. The number, combination, and combination of these can be changed.

-Control based on the size of the paper P placed on the auxiliary tray 8 This control is that when the paper P is placed on the auxiliary tray 8, it receives a strong impact and the paper P is scratched or broken. This is to prevent it.

  That is, when the suction fans 41a, 41a, 42a, and 43a are driven under the same conditions regardless of the size of the paper P, the endless belt 38 is used when the paper P is large and small. Since the transported distance becomes long and the biasing action of the suction fans 41a, 41a, 42a, 43a is received for a long time, the paper P is stacked on the auxiliary tray 8 after the paper P is stacked on the auxiliary tray 8. When transported toward the refeed positioning member 24 by the endless belt 38, the thin paper P is in a state of being in close contact with the endless belt 38, is less likely to slip, and is transported with a large transport force. When it comes into contact with the paper 24, it receives a strong impact and the paper P is scratched or broken.

  For example, the A4 size paper is 28 mm shorter than the B5 size paper, so the travel distance is 28 mm longer. The B5 size paper is re-supplied in a state of being in close contact with the endless belt 38 compared to the A4 size paper. When the paper is conveyed toward the paper positioning member 24 and the leading end abuts against the paper refeeding positioning member 24, it is likely to be damaged or broken. In order to prevent this, the control means 129 causes the suction fan 41a, 41a, 42a, 43a to apply the surface-printed paper PA to the endless belt 38 when the paper P is large or small. The suction force application drive circuit 44 is controlled so that the urging force is reduced.

  Specifically, the control unit 129 is the paper size setting key when the size of the paper P detected by the paper size detection sensor 73 and the size of the paper P is input by the paper size setting key 115 during duplex printing. When the size of the paper P input and detected by 115 is smaller than B5, the energizing voltage applied to the downstream fan 42a in the conveyance direction of the paper P by the endless belt 38 is rated by the suction force applying drive circuit 44. As shown in FIGS. 2 and 10 to 15, the output is lowered. As a result, the conveying force of the paper P by the endless belt 38 becomes the same as that of the paper P having a size larger than B5, and when it hits the refeed positioning member 24, it does not receive a strong impact, and the paper P is scratched or broken. Will not occur.

  The condition that the output of the fan 42a is reduced is obtained as a result of an experiment using the double-sided printing apparatus 1. According to this result, the energization voltage to the fan 42a is preferably 16V to 20V. I understood that. If it is greater than 20 V, the paper P may be scratched or broken. If it is less than 16 V, the conveyance force of the paper P by the endless belt 38 will be weak, or the speed at which the paper P will fall will be reduced to the auxiliary tray 8. This is because there was a case where the placement of was not performed smoothly. Since the energization voltage to the fan 42a is preferably 16V to 20V, it is not limited to 20V, and can be lowered in the range of 16V to 20V.

  Further, if the energization voltage of the fan 43a as well as the fan 42a is reduced, the conveyance force of the paper P by the endless belt 38 becomes weak, or the falling speed of the paper P becomes small and the paper P is placed on the auxiliary tray 8. May not go smoothly. Therefore, it is considered that the fan for reducing the output is preferably disposed in the downstream portion in the transport direction X. As for the size condition, it was found that if the output is lowered when the paper P of B5 size or less is placed on the auxiliary tray 8, no damage or the like will occur.

  However, such conditions can be changed as appropriate so as not to damage the leading edge of the paper P. The number and combination of fans that lower the output can be changed, the fan output can be stopped, or the fan can be stopped. The number, combination, and combination of these can be changed. In addition, the paper size for reducing the fan output may be other sizes, or the fan output may be set for each paper size.

  The control unit 129 also controls the suction force application drive circuit 44 to operate the suction fans 41a and 41a and is conveyed by the endless belt 38 during duplex printing, as shown in FIGS. The leading end of the sheet P to be urged and attracted to the sheet conveying surface of the auxiliary tray 8 to prevent the sheet P from getting over the sheet re-feeding positioning member 24 and to be surely engaged with the sheet re-feeding positioning member 24; The paper P is surely occupied at the refeed position.

  Therefore, even if curl or wave is generated on the paper P conveyed by the endless belt 38, the leading edge of the paper P is prevented from coming into contact with the refeed positioning member 24, and the paper P is moved to the refeed position. When the sheet is conveyed again between the plate cylinder 12 and the press roller 13, skew and resist are not deteriorated, and refeeding is performed well.

  As shown in FIG. 11 to FIG. 13, the controller 129 operates the solenoid 33 to operate the re-feeding registration roller 23 in the pressure contact position even during double-sided printing. Is controlled to stop the suction fans 41a and 41a. However, the control means 129 may be configured to always operate the suction fans 41a and 41a during duplex printing. The energization current to the fans 41a and 41a is constant at the rated 24V. However, it can be appropriately changed according to the type and size of the paper P.

  Of the above-described control modes of the driving of the suction fans 41a, 41a, 42a, 42a, 43a, 43a by the control means 129, which is controlled by the suction force application drive circuit 44, an example thereof will be described below. In conjunction with the description of the operation, the description will be made with reference to FIGS.

Based on the above configuration, the operation of the duplex printing apparatus 1 will be described below.
The operator loads 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 the printing mode, and the plate making start key 104 is pressed.
First, a description will be given of an operation when single-sided printing is performed by pressing the single-sided printing key 118, that is, an operation during single-sided printing.

  The operator confirms the single-sided printing mode by turning on the LED 118a, and then presses the plate making start key 104. The control means 129 does not drive the suction fans 41a, 41a, 42a, 42a, 43a, 43a by the suction force application drive circuit 44 under the single-sided printing mode. When the plate making start key 104 is pressed, a paper size detection signal is sent from the paper size detection sensor 73 and a document size detection signal is sent from the document size detection sensor 102 to the control means 129. Compare each signal. At this time, if the paper size and the document size are the same, the image reading operation is immediately performed. If the paper size and the document size are different, the control unit 129 displays the fact on the display device 120 and pays attention to the operator. Prompt. When the paper size and the document size are different, enlargement or reduction may be automatically performed by a command from the control unit 129 so that the document size and the image size are matched.

  When the plate making start key 104 is pressed, the image reading unit 7 performs a document image reading operation. Reading of the document image is performed by reflecting the reflected light exposed by the fluorescent lamp 99 by each of the reflection mirrors 95, 96, 97, and 98. The read document image is focused by the lens 100 and then image sensor 101. And is photoelectrically converted. The photoelectrically converted electrical signal is input to an A / D converter (not shown) in the apparatus main body 11 and then stored as digital image data in the image memory 135.

  In parallel with the image reading operation in the image reading unit 7, the plate discharging unit 5 performs a plate discharging operation for peeling the used master 64 from the outer peripheral surface of the plate cylinder 12. When the plate making start key 104 is pressed, the plate cylinder 12 starts rotating. When the plate cylinder 12 reaches the home position shown in FIG. 1, the dog 133 is detected by the home position sensor 134, and the home position sensor 134 controls the control means 129. A home position signal is sent to. Receiving the home position signal, the control means 129 measures the number of pulses generated by the encoder with the home position as a base point, and the tip of the used master 64 wound on the outer peripheral surface of the plate cylinder 12 is connected to the driven roller 82. When it is determined that the predetermined plate discharging position corresponding to the endless belt 83 located on the outer peripheral surface has been reached, the operation of the plate cylinder driving unit 121 is stopped.

  When the plate cylinder driving unit 121 is stopped and the plate cylinder 12 is stopped at a predetermined plate discharging position, the plate cylinder driving unit 121 and the plate discharging driving unit 126 are operated to rotate and drive the respective driving rollers 78 and 81 and the lower plate discharging member. 75 moves to the plate cylinder 12 side, and the endless belt 83 located on the outer peripheral surface of the driven roller 82 contacts the used master 64 on the plate cylinder 12. Then, the used master 64 scooped up from the outer peripheral surface of the plate cylinder 12 by the rotation of the plate cylinder 12 and the movement of the endless belt 83 is nipped and conveyed by the lower plate discharge member 75 and the upper plate discharge member 74 and is transferred to the plate cylinder 12. It peels from the outer peripheral surface. The used master 64 that has been peeled off is discarded into the discharge box 76 and then compressed by the compression plate 77.

  The plate cylinder 12 continues to rotate even after all the used masters 64 are peeled from the outer peripheral surface, and the clamper 19b rotates to a predetermined plate feed standby position located at the upper right and stops. When the plate cylinder 12 stops at the plate feeding standby position, the opening / closing means is operated to open the clamper 19b, and the duplex printing apparatus 1 enters the plate feeding standby state.

  In parallel with the plate removal operation, the plate making unit 3 performs the plate making operation. When the plate making start key 104 is pressed, the platen roller 58, the tension roller pair 62, and the reverse roller pair 63 are driven to rotate, and the master 64 is pulled out from the master roll 64a. At this time, the movable master guide plate is positioned at the transport position. When the master 64 is pulled out and the image forming area reaches a position corresponding to the heating element of the thermal head 59, the image data signal stored in the image memory 135 is called after image processing is performed, and the thermal head The driver selectively causes each heating element of the thermal head 59 to generate heat, whereby a third plate-making image 64 c is formed on the thermoplastic resin film surface of the master 64. When the master 64 is transported while making a plate and its tip is sandwiched between the reverse roller pair 63, the movable master guide plate is moved to the retracted position and the rotation of the reverse roller pair 63 is stopped.

  The platen roller 58 and the tension roller pair 62 continue to rotate even after the rotation of the reversing roller pair 63 is stopped, and the master 64 that has been made by the thermal head 59 is stored in the master stock unit 61. When the reversing roller pair 63 is stopped, the suction fan is operated, and the master 64 that has been subjected to plate making is sucked by the suction fan and stored well in the master stock section 61.

  During the above-described plate making operation, when the plate discharging operation is completed and the duplex printing apparatus 1 enters the plate feed standby state, the reverse roller pair 63 starts to rotate, and the pre-made master 64 stored in the master stock unit 61 is stored. Is conveyed toward the stage portion 19a and the opened clamper 19b. When the leading end of the master 64 that has been made is transported to a predetermined position that can be clamped by the clamper 19b, the opening / closing means is actuated to close the clamper 19b. It is held on the outer peripheral surface of the plate cylinder 12 by the clamper 19b.

  Thereafter, the plate cylinder 12 is intermittently rotated in the clockwise direction in FIG. 1, and the winding operation of the pre-made master 64 around the plate cylinder 12 is performed. At this time, the reversing roller pair 63 stops rotating, and the driving roller 63a is rotated along with the normal drawing-out master 64 being pulled out by a one-way clutch provided therein.

  When the digital image data signal from the image memory 135 is interrupted, the operation of the thermal head 59 stops, and when a normal plate-making master 64 for one plate is conveyed, the platen roller 58, the tension roller pair 62, and the reverse roller pair. The rotation of 63 is stopped, and the cutting means 60 is operated to cut the master 64 that has been made. The master 64 that has been subjected to the plate making is pulled out of the plate making unit 3 by the rotation of the plate cylinder 12, and the plate cylinder 12 rotates to the home position and stops, whereby the plate making operation and the plate feeding operation are completed.

The printing operation is performed following the plate feeding operation. When the plate cylinder 12 stops at the home position, the solenoid 123 is actuated to position the switching member 10 at the first position.
Thereafter, the paper feed roller 68, the separation roller 69, the drive roller 87, and the suction fan 90 are driven, and the plate cylinder 12 is driven to rotate in the clockwise direction in FIG. The uppermost sheet of the paper P is pulled out and the leading end is sandwiched between the registration roller pair 71. The drive roller at a predetermined timing when the image area leading end of the third plate-making image 64c in the plate-cylinder rotation direction of the master-printed master 64 wound on the plate cylinder 12 reaches a position corresponding to the press roller 13. 71 a is driven to rotate, and the drawn paper P is fed between the plate cylinder 12 and the press roller 13.

  In synchronization with the rotation of the plate cylinder 12, the press roller 13 is pressed against the outer peripheral surface of the plate cylinder 12 by the press roller contact / separation mechanism 55, and the paper P fed by the resist roller pair 71 is transferred to the plate cylinder. 12 is pressed by the master 64 that has been pre-rolled around the plate 12. By this pressing operation, the press roller 13, the paper P, the master master 64 and the plate cylinder 12 are pressed against each other, and the ink supplied to the inner peripheral surface of the plate cylinder 12 by the ink roller 16 oozes out from the opening of the plate cylinder 12. Then, after being filled in a porous support plate and mesh screen, and the porous support body of the master plate master 64 wound around the plate cylinder 12, it is transferred to the paper P through the perforated portion of the master plate master plate 64. So-called printing is performed.

  The sheet P on which an image corresponding to the third plate-making image 64c is printed by printing is guided to the paper discharge conveyance unit 85 by the switching member 10 that has become the printed sheet PB and occupies the first position. Then, the peeling claw 84 and the fan 40a are actuated to peel from the normal master-made master 64 on the outer peripheral surface of the plate cylinder from the leading ends thereof, and are conveyed by the paper discharge conveyance unit 85 as shown in FIGS. In this state, there is no front-side printed paper PA2 shown in FIG. 14 and front-side printed paper PA1 shown in FIG.

The printed paper PB that has been peeled off from the normal plate-making master 64 on the outer periphery of the plate cylinder by the operation of the peeling claw 84 and the fan 40a falls downward and is sent to the paper discharge transport unit 85. As shown in FIG. 15, while being attracted to the upper surface of the endless belt 89 by the suction force of the suction fan 90, it is conveyed leftward and discharged onto the paper discharge tray 86. In this state, there is no front printed paper PA2 shown in FIG. When the printed paper PB is printed with an image corresponding to the third plate-making image 64c, the press roller 13 occupies the separated position.
Thereafter, the plate cylinder 12 is rotated again to the home position and stopped, and the plate printing operation is finished, and the duplex printing apparatus 1 enters a print standby state.

  After the duplex printing apparatus 1 is in a print standby state, a test print is performed when the test print key 106 is pressed after inputting print conditions using the print speed setting key 113 and various keys on the operation panel 103. During this time, the control means 129 does not drive the suction fans 41a, 41a, 42a, 42a, 43a, 43a by the suction force application drive circuit 44 under the single-sided printing mode.

  When the trial printing key 106 is pressed, the plate cylinder 12 is driven to rotate at the set printing speed and one sheet P is fed from the sheet feeding unit 4. The fed paper P is temporarily stopped by the registration roller pair 71 and then fed at the same timing as that at the time of printing. The press roller 13 is pressed against the master 64 on the outer periphery of the plate cylinder.

The printed paper PB on which the image is printed is guided to the paper discharge unit 6 by the switching member 10, and then peeled off from the normal pre-made master 64 on the outer periphery of the plate cylinder by the operation of the peeling claw 84 and the fan 40a. Then, as shown in FIGS. 14, 2, and 15, the paper is transported by the paper discharge transport unit 85 and discharged onto the paper discharge tray 86. It is transported by the paper discharge transport unit 85. In this state, there is no front surface printed paper PA2 shown in FIGS. 14 and 15 and front surface printed paper PA1 shown in FIG.
When the printed paper PB is printed with an image corresponding to the third plate-making image 64c, the press roller 13 occupies the separated position.
Thereafter, the plate cylinder 12 is rotated again to the home position and stopped, and the plate printing operation is finished, and the duplex printing apparatus 1 enters a print standby state.

  When the position or density of the image is confirmed by the trial printing and the print start key 105 is pressed after the number of prints is input by the ten key 109, the paper P is continuously fed from the paper feeding unit 4 and the trial printing is performed. The printing operation is performed under the same conditions. During this time, the control means 129 does not drive the suction fans 41a, 41a, 42a, 42a, 43a, 43a by the suction force application drive circuit 44 under the single-sided printing mode. When the set number of prints is consumed, the plate cylinder 12 stops at the home position, and the duplex printing apparatus 1 enters the print standby state again.

Next, a case where double-sided printing is performed by pressing the double-sided printing key 117, that is, an operation during double-sided printing will be described.
The operator confirms that the duplex printing mode is in effect by turning on the LED 117a, and then presses the paper thickness setting key 116 to set the thickness of the paper P to be used. The control unit 129 drives the suction fans 41a, 41a, 42a, 42a, 43a, 43a as appropriate by the suction force application drive circuit 44 in the double-sided printing mode. In the duplex printing mode, if the sheet thickness setting key 116 is not pressed, the input of the plate making start key 104 is rejected. If the plate making start key 104 is pressed without pressing the sheet thickness setting key 116, the control means A display 129 displays on the display device 120 that the sheet thickness should be set.

  In this embodiment, when the thickness of the paper P set by the paper thickness setting key 116 is “plain paper” or “thin paper”, the input of the plate making start key 104 is permitted and “thick paper” is set. In order to prevent the paper P from being jammed, the input of the plate making start key 104 is rejected, and the control means 129 displays a warning to the effect that the correct paper should be set on the display device 120.

  When the sheet P, which is “plain paper” or “thin paper”, is set on the sheet feed tray 67 and the sheet thickness based on the sheet P is set by the sheet thickness setting key 116, the plate making start key 104 is pressed. As in the case of single-sided printing, a paper 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 the present embodiment, since the maximum paper size that can be printed by the plate cylinder 12 is A3 size, the paper size that can be used in 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 operator. When the paper size and the document size are different, a configuration in which enlargement or reduction is automatically performed according to a command from the control unit 129 to match the document size and the image size, and the display device 120 is configured to reduce or reduce the size of the image data. It is good also as a structure which displays the procedure, such as rotation, and assists an operator's operation. When the paper size exceeds A4 landscape, the control unit 129 may display on the display device 120 a message that prohibits double-sided printing and prompts single-sided printing. In the following description, it is assumed that B5-size plain paper is used as the paper P.

  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 original is completed and the digital image data is stored in the image memory 135, the control means 129 displays that the second original should be set on the display device 120. Make it.

  The operator opens the pressure plate 94 in accordance with this display, 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 the second digital image data.

  In this embodiment, the document reading operation in the single-sided printing mode and the double-sided printing mode is configured such that the operator sets the document to be read on the contact glass 93 by opening and closing the pressure plate 94, but using the ADF. A configuration in which an original is automatically conveyed onto the contact glass 93 or a configuration in which digital image data is taken in from an external device (not shown) may be employed. The same applies to the single-sided printing mode. 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 64 has been peeled off from the outer peripheral surface stops at the plate feed standby position, and the clamper 19b is opened by the opening / closing means. 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 64a and the second plate making image 64b are formed on the surface of the thermoplastic resin film in the master 64.

  The divided master-making master 64 is stored in the master stock unit 61, and when the plate-removing operation is completed and the duplex printing apparatus 1 enters the plate-feed standby state, the clamper opened from the stage unit 19a by the operation of the reversing roller pair 63. It is conveyed toward 19b. Thereafter, the plate cylinder 12 is intermittently rotated in the same manner as in the single-sided printing mode, and the master 64 that has been subjected to divided plate making is wound around the plate cylinder 12.

  When all two pieces of digital image data have been sent from the image memory 135, the cutting means 60 is operated to cut the master 64 that has been subjected to divided plate making. The cut master plate 64 that has been divided is drawn 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.

  The printing operation is performed following the plate feeding operation. When the plate cylinder 12 stops at the home position, the paper feed roller 68, the separation roller 69, the drive rollers 36 and 87, and the suction fan 90 are driven, and the plate cylinder 12 is rotated at a low speed in the clockwise direction in FIG. Then, the first sheet P is pulled out from the sheet feed tray 67 and the leading end thereof is sandwiched between the registration roller pair 71.

  At this time, the control unit 129 drives the suction fans 41a, 41a, 42a, and 42a by the suction force application drive circuit 44, but the sheet P is not yet placed on the auxiliary tray 8; The suction fans 43a and 43a are not driven. Since the size of the paper P is B5, the suction fan 42a is driven at 20V, which is lower than the rated 24V.

  When the clamper 19b passes through a position corresponding to the switching member 10, the solenoid 123 is activated to position the switching member 10 at the second position. The master 64 wound on the plate cylinder 12 is driven at a predetermined timing when the leading end of the image area 64a of the first plate making image 64a in the rotation direction of the plate cylinder reaches the position corresponding to the press roller 13. When the roller 71 a is driven to rotate, the drawn first sheet P is fed between the plate cylinder 12 and the press roller 13.

  In synchronization with the rotation of the plate cylinder 12, the press roller 13 is pressed against the outer peripheral surface of the plate cylinder 12 by the press roller contact / separation mechanism 55. As a result, the first sheet P fed by the press roller 13, the registration roller pair 71, the first plate-making image 64a forming portion of the master 64 that has been divided and plate-making, and the plate cylinder 12 are pressed against each other. After the ink supplied to the inner peripheral surface of the plate cylinder 12 oozes out from the opening of the plate cylinder 12 and is filled into the porous support plate and mesh screen, and the porous support body of the master 64 that has been divided and made, the first The portion of the master 64 that has been transferred to the first sheet P through the perforated portion of the plate-making image 64a and has the first plate-making image 64a formed in the divided plate-making master 64 is printed.

  An image corresponding to the first plate-making image 64a is printed on the surface of the first sheet P, and the first sheet P, which is a surface-printed sheet PA, is divided on the outer peripheral surface of the plate cylinder from one end by the tip of the switching member 10. While being peeled from the master 64 that has been subjected to plate making, it is guided to the paper re-feeding means 9 by the switching member 10 occupying the second position.

  The plate cylinder 12 continues to rotate while the first sheet P is being guided to the re-feeding means 9, and the press roller 13 is moved by the press roller contact / separation mechanism 55 of the master 64 that has been subjected to divided plate making. When the contact with the first plate-making image 64a forming portion is finished, it occupies a separated position. Therefore, the press roller contact / separation mechanism 55 prevents the back surface area of the plate cylinder 12 and the press roller 13 from being in pressure contact with each other in the absence of the paper P, thereby preventing ink transfer to the peripheral surface of the press roller 13. Is done.

  As shown in FIG. 10, the surface-printed paper PA guided downward by the switching member 10 passes between the guide plates 27 and 56, and thereafter, one end thereof is brought into contact with the end fence 8 a to complete the divided plate-making. 13 and 14 while the blank portion S of the master 64 passes through the area facing the press roller 13 and the second plate-making image 64b forming portion passes through the area facing the press roller 13. Like the printed paper PA, it is placed on the auxiliary tray 8. In this state, there is no printed paper PB shown in FIGS.

At this time, the controller 129 does not drive the suction fan 43a by the suction force application drive circuit 44, so that the front-side printed paper PA is placed on the auxiliary tray 8 without being rounded.
When the size of the paper P is larger than B5 and is plain paper, the suction fan 42a is driven at the rated value.
The controller 129 causes the suction fan 43a to start driving the suction fan 43a at the timing when the front surface printed paper PA is placed on the auxiliary tray 8.

  The surface-printed paper PA conveyed on the auxiliary tray 8 is rotated at a speed determined by the printing conditions as described above by the suction force of the suction fan 42a having a low output and the suction fan 43a having a rated output. As shown in FIG. 2, the other end, that is, the rear end when the first plate-making image 64a is printed, in other words, the front end after being transported by the transport means 21, is re-feeded. At the same time as the contact with the positioning member 24, a command is sent from the control means 129, and the operation of the drive roller 36 is stopped. In this state, there is no printed paper PB shown in FIG.

At this time, since the suction fan 41a is driven by the suction force application driving circuit 44, the control unit 129 reliably contacts the leading edge of the surface printed paper PA with the refeed positioning member 24 and has the surface printed. The paper PA stops in a state where the paper re-feed position is occupied.
The stop and start of the conveyance of the front surface printed paper PA, particularly the stop, is endless as described above after the sensor 8c detects the front surface printed paper PA or according to the operation timing of the plate cylinder driving means 121 or the like. The surface-printed paper PA is buckled because it is performed according to the rotational speed of the belt 38, and the outputs of the suction fans 42a and 43a and the frictional resistance of the endless belt 38 are set as described above. Occupies the refeeding position without causing any deflection.

  The paper feed roller 68 and the separation roller 69 are driven almost simultaneously with the operation of bringing the front surface printed paper PA into contact with the refeed positioning member 24, and the second paper P is pulled out from the paper feed tray 67 and its leading edge. Is held between 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.

  At this time, in the plate cylinder 12, the non-opening portion which is a portion other than the first plate making image 64 a forming portion, the second plate making image 64 b forming portion, and the blank portion S of the divided plate making master 64 is opposed to the press roller 13. Occupies a position to do. In addition, the solenoid 123 is operated until the first plate-making image 64a forming portion of the master 64 that has been divided and plate-making passes the portion facing the press roller 13 and the clamper 19b again occupies the position corresponding to the switching member 10. The switching member 10 is displaced from the second position to the first position.

  At a predetermined timing when the second sheet P is fed by the registration roller pair 71, the press roller contact / separation mechanism 55 presses the peripheral surface of the press roller 13 against the outer peripheral surface of the plate cylinder 12. As a result, the press roller 13, the second sheet P, the first plate-making image 64 a forming portion of the master 64 that has been divided and plate-making, and the plate cylinder 12 are pressed against each other, and are supplied to the inner peripheral surface of the plate cylinder 12 by the ink roller 16. The transferred ink is transferred onto the second sheet P through the opening of the plate cylinder 12, the porous support plate and the mesh screen, and the perforated portion of the first plate-making image 64a.

  The second sheet P, which has been printed with an image corresponding to the first plate-making image 64a and has become a printed sheet PB, is guided to the sheet discharge conveyance unit 85 by the switching member 10 occupying the first position, and The peeling claw 84 and the fan 40a are actuated to peel off from one end of the master 64, which has already been divided and made on the outer periphery of the plate cylinder. The peeled printed paper PB is dropped downward and sent to the paper discharge transport unit 85, and then transported by the paper discharge transport unit 85 as shown in FIG.

  After the second sheet P is fed by the registration roller pair 71, the position of the front end of the image area of the second plate-making image 64b in the plate cylinder rotation direction of the master plate 64 that has been subjected to divided plate-making corresponds to the press roller 13. The solenoid 33 is actuated and the swing arm 32 is swung at a predetermined timing which is slightly earlier than reaching the position. As a result, the re-feed registration roller 23 is swung from the separation position to the press-contact position, and the front-side printed paper PA that has been stopped with the other end in contact with the re-feed positioning member 24 contacts the plate cylinder 12. It is in contact with the peripheral surface of the press roller 13 that is in contact with and is rotated. The control unit 129 operates the solenoid 33 and at the same time stops the operation of the suction fan 41 a by the suction force application drive circuit 44.

  The surface-printed paper PA abutted on the peripheral surface of the press roller 13 by the re-feeding registration roller 23 is rotated by the rotational force of the press roller 13 like the surface-printed paper PA1 shown in FIGS. It is conveyed toward the downstream side in the direction, and conveyed toward the contact portion with the plate cylinder 12 while being in close contact with the peripheral surface of the press roller 13 by the paper guide plate 31 and the rollers 28, 29, and 30. In this state, there is no front printed paper PA2 shown in FIGS.

  At this time, an image corresponding to the first plate-making image 64a is printed on the surface of the surface-printed paper PA, but the surface-printed paper PA is brought into close contact with the peripheral surface of the press roller 13 by the action of the refeed guide member. Therefore, the surface-printed paper PA once in contact with the peripheral surface of the press roller 13 is not displaced, and the occurrence of problems such as rubbing dirt or thickening of the image line is prevented.

On the other hand, the printed paper PB is transported leftward by the paper discharge transport unit 85 and discharged onto the paper discharge tray 86. When the printed paper PB is printed with an image corresponding to the first plate-making image 64a, the press roller 13 occupies the separated position.
In the front-side printed paper PA, after the first plate-making image 64a forming portion and the blank portion S of the divided master-making master 64 pass through the position corresponding to the press roller 13, the front end portion of the back surface region corresponds to the press roller 13. It is fed into the contact portion between the plate cylinder 12 and the press roller 13 at the timing of reaching the position.

  As a result, the press roller 13, the surface-printed paper PA, the second plate-making image 64 b forming part of the master 64 that has been subjected to divided plate-making, and the plate cylinder 12 are pressed against each other and supplied to the inner peripheral surface of the plate cylinder 12 by the ink roller 16. The ink is transferred to the back surface of the surface-printed paper PA through the opening of the plate cylinder 12, the porous support plate and the mesh screen, and the perforated portion of the second plate-making image 64b. The portion where the plate-making image 64b is formed is printed.

  An image corresponding to the first plate-making image 64a is printed on the front surface, and an image corresponding to the second plate-making image 64b is printed on the back surface. While being brought into contact with the circumferential surface of the press roller 13 and being transported by the rotational force of the press roller 13, the switching member 10 occupying the first position is guided to the paper discharge transport unit 85, and the separation claw 84 and the fan By the operation of 40a, it is peeled off from one end of the master 64 which has been divided and made on the outer peripheral surface of the plate cylinder. The peeled printed paper PB falls downward and is sent to the paper discharge transport unit 85 as shown in FIG. In this state, there is no front printed paper PA2 shown in FIG.

  As shown in FIG. 13, when the rear end of the printed paper PB passes the position where the sensor 8c is disposed, the solenoid 33 is stopped and the re-feeding registration roller 23 is moved from the press contact position as shown in FIG. It is displaced to the separated position. In this state, there is no surface printed paper PA2 shown in FIGS.

As shown in FIG. 15, the printed paper PB sent to the paper discharge transport unit 85 is further transported and transported to the left while being attracted to the upper surface of the endless belt 89 by the suction force of the suction fan 90. . In this state, there is no front printed paper PA2 shown in FIG.
When the printed paper PB is printed with an image corresponding to the second plate-making image 64b, the press roller 13 occupies the separated position.
The printed paper PB is further conveyed and discharged onto the paper discharge tray 86.

  The control means 129 continues the operation of the double-sided printing apparatus 1, and the plate cylinder 12 rotates again to the home position and stops. As a result, the printing operation of the master 64 that has been divided and made is completed, and the double-sided printing apparatus 1 enters a print standby state. The control means 129 stops the suction fans 42 a and 43 a by the suction force application drive circuit 44.

  At the time of the above-mentioned plate-making, a blank portion S is provided between the first plate-making image 64a and the second plate-making image 64b of the master 64 that has been divided and made, and the master 64 that has been divided and made is on the outer peripheral surface of the plate cylinder 12. Since the intermediate area is formed when the paper is wound on the paper, the rear end of the second paper P sent from the paper supply unit 4 and the front end of the front surface printed paper PA sent from the refeed means 9 Is prevented from being polymerized and good printing is performed.

  When re-feeding the surface-printed paper PA from the re-feed means 9, the ink from the surface-printed paper PA is transferred again to the surface of the press roller 13 by contacting the printing surface of the surface-printed paper PA. However, since the peripheral surface of the press roller 13 has ink repellency and the cleaning roller 26 cleans the peripheral surface of the press roller 13, the amount of retransfer ink from the surface-printed paper PA to the peripheral surface of the press roller 13 is reduced. At the same time, the removal of the retransfer ink from the peripheral surface of the press roller 13 is promoted, and the retransfer of the ink from the press roller 13 to the back surface of the paper P is prevented during the following printing.

  After the duplex printing apparatus 1 is in a print standby state, after entering predetermined printing conditions such as the printing speed, the size and type of the paper P using the printing speed setting key 113 and various keys on the operation panel 103, the trial printing key 106 When is pressed, trial printing is performed. Even when the trial printing key 106 is pressed, the control means 129 displays a message to the effect that the paper thickness should be set on the display device 120. When “thick paper” is set, the input of the trial printing key 106 is performed. And a warning that the correct paper should be set is displayed on the display device 120.

  When the trial printing key 106 is pressed, the plate cylinder 12 is rotationally driven as in the case of plate printing, and the switching member 10 is positioned at the second position as in the case of plate printing. After that, the test printing is performed in the same manner as the plate printing, and the printed paper PB which has been printed on both sides is peeled off from the divided master-making master 64 by the operation of the peeling claw 84 and the fan 40a, and is transported by the paper discharge transport unit 85. The test printing is completed by being discharged onto the paper discharge tray 86.

  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 printing operation is performed. Even when the print start key 105 is pressed, the control means 129 displays a message to the effect that the paper thickness should be set on the display device 120. If “thick paper” is set, the print start key 105 is input. And a warning that the correct paper should be set is displayed on the display device 120.

Hereinafter, a case where N sheets are input as the number of printed sheets will be described.
When the print start key 105 is pressed, the plate cylinder 12 is driven to rotate, and the switching member 10 is positioned at the second position as in the case of printing and test printing. After the plate cylinder 12 starts rotating, the first sheet P is fed from the sheet feeding unit 4, and the fed first sheet P is temporarily stopped by the registration roller pair 71 and then at the same timing as the trial printing. It is sent by.

  At this time, the controller 129 causes the suction fan 41a to drive the suction fans 41a, 41a, and 42a. However, since the sheet P is not yet placed on the auxiliary tray 8, the suction fan 41a is driven. 43a is not driven. Since the size of the paper P is B5, the suction fan 42a is driven at 20V, which is lower than the rated 24V.

The first sheet P is pressed against the first plate-making image 64a of the master 64 that has been divided and made by the press roller 13, so that an image corresponding to the first plate-making image 64a is printed on the surface, and FIG. As shown in the figure, the first surface-printed paper PA is peeled and guided by the switching member 10 occupying the second position, and the first plate-making image 64a forming portion and the blank portion S of the master 64 that has been subjected to the plate-making are divided. In the middle of passing the area facing the press roller 13 and the second plate-making image 64b forming area passing the area facing the press roller 13, like the surface-printed paper PA2 shown in FIGS. It is conveyed onto the auxiliary tray 8.
In this state, the printed paper PB shown in FIGS. 13, 14, and 2 is not present. The press roller 13 is held at the separated position by the operation of the press roller contacting / separating mechanism 55.

At this time, the controller 129 does not drive the suction fan 43a by the suction force application drive circuit 44, so that the front-side printed paper PA is placed on the auxiliary tray 8 without being rounded.
When the size of the paper P is larger than B5 and is plain paper, the suction fan 42a is driven at the rated value.
The controller 129 causes the suction fan 43a to start driving the suction fan 43a at the timing when the front surface printed paper PA is placed on the auxiliary tray 8.

  The surface-printed paper PA conveyed on the auxiliary tray 8 is rotated at a speed determined by the printing conditions as described above by the suction force of the suction fan 42a having a low output and the suction fan 43a having a rated output. As shown in FIG. 2, the other end, that is, the rear end at the time of printing the first plate-making image 64a is brought into contact with the re-feeding positioning member 24, and is controlled almost simultaneously with this. A command is sent from the means 129 and the operation of the drive roller 36 is stopped. In this state, there is no printed paper PB shown in FIG.

At this time, since the suction fan 41a is driven by the suction force application driving circuit 44, the control unit 129 reliably contacts the leading edge of the surface printed paper PA with the refeed positioning member 24 and has the surface printed. The paper PA stops in a state where the paper refeeding position is occupied.
The stop and start of the conveyance of the front surface printed paper PA, particularly the stop, is endless as described above after the sensor 8c detects the front surface printed paper PA or according to the operation timing of the plate cylinder driving means 121 or the like. The surface-printed paper PA is buckled because it is performed according to the rotational speed of the belt 38, and the outputs of the suction fans 42a and 43a and the frictional resistance of the endless belt 38 are set as described above. Occupies the refeeding position without causing any deflection.

  Thereafter, 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 directed to the printing unit 2 at the same timing as the first sheet P. Are sent. The switching member 10 is positioned at the first position so as to avoid a collision with the clamper 19b, and is then positioned again at the second position after passing through the clamper 19b.

  The fed second sheet P is pressed against the first plate making image 64a of the master 64 which has been divided and made by the press roller 13, and an image corresponding to the first plate making image 64a is printed on the front surface. After the surface-printed paper PA is obtained, as shown in FIG. 11, it is guided to be peeled off by the switching member 10 occupying the second position, and falls toward the auxiliary tray 8.

  At this time, since the surface-printed paper PA1 is already placed on the auxiliary tray 8, the control unit 129 does not stop the suction fan 43a from being driven by the suction force application drive circuit 44, but the surface-printed paper has been printed. Since the surface-printed paper PA1 is already placed on the auxiliary tray 8, the paper PA2 is not excessively affected by the suction fan 43a, and thus the front-printed paper PA2 is not rounded at the front end. 8 will be placed.

  Thereafter, the solenoid 33 is operated at the same timing as the trial printing, the re-feeding registration roller 23 is displaced from the separation position to the press-contact position, and the first front-side printed paper PA1 that has been stopped on the auxiliary tray 8 is removed. It is conveyed toward the plate cylinder 12 by the rotational force of the press roller 13. The control unit 129 operates the solenoid 33 and at the same time stops the operation of the suction fan 41 a by the suction force application drive circuit 44.

  As shown in FIG. 12, the rear end of the second surface-printed paper PA 2 passes through the contact portion between the plate cylinder 12 and the press roller 13, and is between the lower surface of the switching member 10 and the peripheral surface of the press roller 13. After passing through a slight gap, it is guided toward the auxiliary tray 8 through the guide plates 27 and 56. In the middle of this, the solenoid 123 is actuated immediately before the blank portion S of the master 64 that has undergone divided plate making occupies the position facing the press roller 13, and the switching member 10 is displaced from the second position to the first position.

  As a result, in the first surface-printed paper PA, the blank portion S of the master plate 64 that has been subjected to the plate making process passes through the region facing the press roller 13, and the second plate making image 64 b forming portion faces the press roller 13. It is sent to the contact portion between the plate cylinder 12 and the press roller 13 at timing, and is pressed against the second plate making image 64b of the master 64 that has been divided and made by the press roller 13, so that the second plate making image 64b is formed on the back surface thereof. Corresponding images are printed to become printed paper PB. At this time, as shown in FIG. 13, the second surface-printed paper PA continues to fall with one end in contact with the end fence 8a.

  An image corresponding to the first plate-making image 64a is printed on the front surface, and an image corresponding to the second plate-making image 64b is printed on the back surface, and the first sheet P, which has become a printed sheet PB, occupies the first position. The switching member 10 guides the sheet to the paper discharge / conveyance unit 85, and the operation of the peeling claw 84 and the fan 40a peels from one end of the master plate 64 on the outer periphery of the plate cylinder, and falls downward. The paper is conveyed to the paper discharge conveyance unit 85.

  When the trailing edge of the first printed sheet PB passes the position where the sensor 8c is disposed, the solenoid 33 is stopped and the re-feeding registration roller 23 is moved from the press contact position to the separation position as shown in FIG. Is displaced. The control unit 129 stops the solenoid 33 and simultaneously starts the operation of the suction fan 41a by the suction force application drive circuit 44. Subsequently, the second surface-printed paper PA is stacked on the auxiliary tray 8.

At this time, as shown in FIG. 14, the first printed sheet PB sent to the paper discharge transport unit 85 is shown in FIG. 15 while being attracted to the upper surface of the endless belt 89 by the suction force of the suction fan 90. Is further conveyed to the left.
When the printed paper PB is printed with an image corresponding to the second plate-making image 64b, the press roller 13 occupies the separated position.

  The surface-printed paper PA that has fallen on the auxiliary tray 8 is rotated at a speed determined by the printing conditions as described above by the suction force of the suction fan 42a having a low output and the suction fan 43a having a rated output. 1 and conveyed in the direction of the arrow in FIG. 1, and as shown in FIG. 2, the rear end at the time of printing the other end, that is, the first plate-making image 64a, in other words, transported by the transport means 21, and the subsequent leading end is re-feeded. It abuts on the positioning member 24. At substantially the same time, a command is sent from the control means 129 and the operation of the drive roller 36 is stopped.

At this time, since the suction fan 41a is driven by the suction force application driving circuit 44, the control unit 129 reliably contacts the leading edge of the surface printed paper PA with the refeed positioning member 24 and has the surface printed. The paper PA stops in a state where the paper re-feed position is occupied.
The stop and start of the conveyance of the front surface printed paper PA, particularly the stop, is endless as described above after the sensor 8c detects the front surface printed paper PA or according to the operation timing of the plate cylinder driving means 121 or the like. The surface-printed paper PA is buckled because it is performed according to the rotational speed of the belt 38, and the outputs of the suction fans 42a and 43a and the frictional resistance of the endless belt 38 are set as described above. Occupies the refeeding position without causing any deflection.
The control unit 129 continues the operation of the duplex printing apparatus 1, and the first printed sheet PB is further conveyed and discharged onto the discharge tray 86 as shown in FIG.

  Thereafter, 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 position to avoid a collision with the clamper 19b, and is positioned again at the second position after passing through the clamper 19b. The fed third paper P is printed on the front surface with an image corresponding to the first plate-making image 64 a to be a front-printed paper PA, and then is 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 toward the plate cylinder 12. At this time, an appropriate gap is formed between the rear end of the first surface-printed paper PA and the front end of the second surface-printed paper PA, thereby preventing double feed.

Thereafter, the same printing operation is repeated, the Nth printed sheet PB is discharged onto the discharge tray 86, and the printing of N sheets is completed. The paper PA stops in a state where it occupies the refeeding position.
In the process of printing N sheets, the stop and start of the conveyance of the surface-printed paper PA, in particular the stop, is determined after the sensor 8c detects the surface-printed paper PA or according to the operation timing of the plate cylinder driving unit 121, etc. Thus, since it is performed according to the rotational speed of the endless belt 38 as described above, and the output of the suction fans 42a and 43a and the frictional resistance force of the endless belt 38 are set as described above, Since the surface-printed paper PA occupies the refeeding position without causing buckling or deflection, it is particularly difficult to use a recording medium that is relatively weak, such as medium-size paper or renewed paper. Even when a weak recording medium is transported in a direction perpendicular to the eye direction and printing is performed, re-feeding is always performed favorably and duplex printing is performed favorably.

  Even if the operation of the solenoid 33 is stopped after the Nth surface-printed paper PA, which has been stopped on the auxiliary tray 8, is sent out toward the plate cylinder 12, the control means 129 does not apply the suction force. The drive circuit 44 does not start the operation of the suction fan 41a. The plate cylinder 12 is stopped at the home position, and the double-sided printing apparatus 1 finishes the printing operation and enters the print standby state again. The control means 129 stops the suction fans 42 a and 43 a by the suction force application drive circuit 44.

  During the above-described printing, a blank portion S is provided between the first plate-making image 64 a and the second plate-making image 64 b of the master 64 that has been subjected to divided plate making, and the master 64 that has undergone divided plate making is provided on the outer peripheral surface of the plate cylinder 12. Since the intermediate region is formed when the paper is wound, the trailing edge of the paper P sent from the paper feeding unit 4 and the front edge of the front surface printed paper PA sent from the refeeding means 9 may overlap. Thus, the paper P from the paper feeding unit 4 can be reliably conveyed to the auxiliary tray 8 and the surface-printed paper PA from the refeeding means 9 can be reliably conveyed to the paper discharge tray 86 by switching the switching member 10. .

  Further, when re-feeding the surface-printed paper PA from the re-feeding means 9, the surface of the press roller 13 is printed on the surface by contacting the printing surface of the surface-printed paper PA and the outer peripheral surface of the plate cylinder 12. Although the ink from the paper PA and the ink from the outer peripheral surface of the plate cylinder can be transferred again, the peripheral surface of the press roller 13 has ink repellency and the cleaning roller 26 cleans the peripheral surface of the press roller 13. The re-transfer ink from the used paper PA to the peripheral surface of the press roller 13 is reduced and the removal of the re-transfer ink from the peripheral surface of the press roller 13 is promoted. It is possible to prevent retransfer of ink to the ink.

  According to the double-sided printing apparatus 1, not only can single-sided printing be performed in the same way as a normal stencil printing apparatus during single-sided printing, but also the master-making unit 3 can create a divided master-made master 64 during double-sided printing. The paper is wound around the plate cylinder 12, the first sheet P is fed from the paper feeding unit 4, the surface is pressed against the plate cylinder 12 by the press roller 13, and then discharged onto the auxiliary tray 8. 4, the second sheet P is fed, the surface is pressed against the plate cylinder 12 by the press roller 13, and then discharged onto the auxiliary tray 8, and the first sheet is printed by the refeed unit 9. Since the paper PA is reversed and fed, and the back surface is pressed against the plate cylinder 12 by the press roller 13, the printed paper PB is discharged onto the paper discharge tray 86. Therefore, the front image and the back image printed on the paper P can be obtained. Both press rollers 13 Formed by the ink is transferred from a more plate cylinder 12, it is possible to obtain a good double-sided printed material. Further, the apparatus can be configured without significantly increasing the size as compared with a normal stencil printing apparatus for single-sided printing, and an increase in installation space can be suppressed.

  As described above, the sheet feeding device, the image forming apparatus, the sheet feeding method, and the image forming method to which the present invention is applied have been described as modes for carrying out the present invention. Any device that feeds paper after it has been stopped can be used as a paper feeding device other than the device for performing refeeding. Therefore, even when such a paper feeding device is used for a printing device, the printing device is not limited to a duplex printing device.

  The image forming apparatus is not limited to a printing apparatus, and may be a copying machine, a facsimile machine, a printer, or a complex machine of these. In this case, even if this forms an image on both sides, an image is formed on one side. It may be what performs. A color image may be formed. In the case of forming a color image, for example, it may be a printing apparatus provided with a plurality of plate cylinders for the purpose of performing color printing or the like.

A plurality of paper feeding devices may be provided in the image forming apparatus. In this case, the paper feeding device can be used for each of those that perform paper refeeding and those that do not.
The recording condition can be controlled by using an element for preventing the deflection of the recording medium in addition to the image forming speed, the size, type, and environment of the recording medium.

The driving start, stop, and driving time of the conveying means can be controlled independently of the conveying speed by the conveying means. That is, even when the transport speed is not controlled by the transport means, the drive start, stop, and drive time of the transport means can be controlled according to the recording conditions.
The application of the present invention is not limited to the above-described embodiment unless specifically limited in the above description.

1 is a schematic front view of a double-sided printing apparatus which is a printing apparatus as an image forming apparatus to which the present invention is applied. FIG. 2 is a schematic front view showing an enlargement of a paper feeding device and a paper delivery conveying unit shown in FIG. 1. FIG. 3 is a schematic plan view of a main part of the paper feeding device shown in FIG. 2. FIG. 3 is a schematic front view of a main part of the paper feeding device shown in FIG. 2. FIG. 3 is a schematic sectional side view of a main part of the paper feeding device shown in FIG. 2. It is the schematic of the operation panel with which the double-sided printing apparatus shown in FIG. 1 was equipped. It is a block diagram of the control means with which the double-sided printing apparatus shown in FIG. 1 was equipped. FIG. 2 is a conceptual diagram illustrating a relationship between paper feeding and printing operation during duplex printing of the duplex printing apparatus illustrated in FIG. 1. It is a top view which shows the platemaking aspect of the master used in the double-sided printing apparatus shown in FIG. It is a schematic front view for demonstrating the operation | movement at the time of duplex printing of the duplex printing apparatus shown in FIG. It is a schematic front view for demonstrating the operation | movement in the time different from the time shown in FIG. 10 at the time of double-sided printing of the double-sided printing apparatus shown in FIG. FIG. 12 is a schematic front view for explaining the next operation of the operation shown in FIG. 11 at the time of duplex printing of the duplex printing apparatus shown in FIG. 1. FIG. 13 is a schematic front view for explaining the next operation of the operation illustrated in FIG. 12 during duplex printing of the duplex printing apparatus illustrated in FIG. 1. It is a schematic front view for demonstrating the operation | movement following the operation | movement shown in FIG. 13 at the time of duplex printing of the duplex printing apparatus shown in FIG. FIG. 15 is a schematic front view for explaining the next operation of the operation illustrated in FIG. 14 during duplex printing of the duplex printing apparatus illustrated in FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus, printing apparatus 8c Recording medium detection means 9 Refeed tray, paper feeding apparatus 12 Plate cylinder 20 Seating member 21 Conveying means 24 Locking members 41, 42, 43 Energizing means 129 Control means P, PA, PA1, PA2, PB Recording medium PA, PA1, PA2 Recording medium on which image formation has been performed on one side X Recording medium transport direction Y Direction perpendicular to recording medium transport direction

Claims (17)

A locking member that engages and stops at the leading end of the recording medium for paper feed, and a recording medium transport on a cross section that is disposed upstream of the locking member in the recording medium transport direction and is perpendicular to the transport direction and hips with member forms a convex shape bulging shape from a planar shape portion in close contact with the surface by curving the recording medium in a manner to form a convex portion extending in the same conveying direction with the waist, the recording medium is the engagement and conveying means for conveying the transport direction until it engages the stop member, have a biasing means for biasing the recording medium to the recording medium transportation surface, the waist with member, in the transport direction It is between the said conveyance means and the said latching member, Comprising: It arrange | positions on the extension line | wire of the said conveyance means in the said conveyance direction, The height of the said seating member from a recording medium conveyance surface is set from a recording medium conveyance surface. A sheet feeding device having a height equal to or less than the height of the conveying means . 2. The paper feeding device according to claim 1 , wherein a height of the seating member from the recording medium conveyance surface is equal to or less than a height of the locking member from the recording medium conveyance surface . 3. The paper feeding device according to claim 1 , wherein the locking member is disposed on an extension line of the transporting means in the transport direction . 4. The sheet feeding device according to claim 1 , wherein a height of the conveying unit from the recording medium conveying surface is set to be equal to or lower than a height of the locking member from the recording medium conveying surface. Characteristic paper feeder. 5. The paper feeding device according to claim 1 , wherein a plurality of the seating members and the transporting unit are arranged in a direction perpendicular to the transporting direction . 6. 6. The paper feeding device according to claim 1 , further comprising a control unit that controls driving of the conveying unit . 7. The sheet feeding apparatus according to claim 6 , wherein the control unit transports the recording medium by the transport unit according to at least one recording condition among an image forming speed, a size of the recording medium, a type of the recording medium, and an environment. A paper feeder characterized by changing the speed . 8. The sheet feeding device according to claim 6 , wherein the control unit locks the recording medium according to at least one recording condition among an image forming speed, a size of the recording medium, a type of the recording medium, and an environment. A sheet feeding device characterized in that the drive stop timing of the conveying means after being engaged with a member is changed . The sheet feeding device according to any one of claims 6 to 8 , wherein the control unit is configured according to at least one recording condition of an image forming speed, a size of the recording medium, a type of the recording medium, and an environment . A sheet feeding device characterized in that the driving time of the conveying means is changed. The sheet feeding device according to any one of claims 6 to 9 , wherein the control unit is responsive to at least one recording condition of an image forming speed, a recording medium size, a recording medium type, and an environment . A sheet feeding device that changes a driving start timing of the conveying unit . 9. The sheet feeding device according to claim 6 , wherein the control unit is configured to detect a lapse of a predetermined time from when the control unit passes a predetermined point on the upstream side of the locking member in the recording medium conveyance direction. A sheet feeding device characterized in that the driving of the conveying means is stopped.   12. The paper feeding device according to claim 11, further comprising recording medium detection means for detecting a recording medium disposed at the predetermined point, wherein the control means is based on the detection timing of the recording medium by the recording medium detection means. A paper feeding device that determines when the drive is stopped. An image forming apparatus comprising the sheet feeding device according to claim 1 . The image forming apparatus according to claim 13, an image forming apparatus which is a printing apparatus for recording on a recording medium by using a plate cylinder. 15. The image forming apparatus according to claim 13 , wherein an image can be formed on both sides of a recording medium, and the paper feeding device is a recording medium on which an image is formed on one side, and thereafter the other side. an image forming apparatus comprising the recording medium on which an image formation is performed is provided as re-feeding device to be mounted. Paper for feeding paper using the paper feeding apparatus according to any one of claims 1 to 12. An image forming method for forming an image using the image forming apparatus according to claim 13 or the paper feeding method according to claim 16 .

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