JP2005153175A - Stencil printing equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide stencil printing equipment which is capable of printing printed matter suited for the characteristics of a copy image and a double-sided image that a user desires, by adopting a constitution which can arbitrarily change a subscanning direction feeding density between platemaking areas corresponding respectively to a front-side image and a back-side image on the occasion of forming the double-sided image. <P>SOLUTION: In the stencil printing equipment enabling double-sided printing, a thermal stencil master 64 having a thermoplastic resin film is moved in the subscanning direction F by a master carrying means 224, while the master is pressed by a platen roller 58 against a perforating means 59 having a large number of heating parts arranged in the main scanning direction S, and the thermoplastic resin film is melted and perforated selectively by making the heating parts heat in accordance with image signals, so as to form a perforated pattern according to the image signals. The master being wound on the outer peripheral surface of a printing drum 12, ink is supplied from inside the drum and an ink image is printed on printing paper P according to the image signals with the ink oozing out through the perforated pattern. The equipment is so constituted that the resolution in the subscanning direction F can be set by a subscanning direction resolution setting means 112 for each of a first copy corresponding to the front-side image and a second copy corresponding to a second copy on the occasion of the double-sided printing. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a stencil printing apparatus capable of duplex printing capable of arbitrarily changing the feed density in the sub-scanning direction between plate making areas corresponding to a front image and a back image.

  In the stencil printing apparatus, in recent years, due to environmental problems, double-sided printing that performs printing on both sides of the printing paper has been increasing for reasons such as saving printing paper and preventing an increase in files. In general, double-sided printing is obtained by turning over a printing paper that has been printed once and feeding it again, but there is a problem that the procedure for feeding paper again is troublesome. In addition, since the opposite side is printed after the single-sided printing is completed, double-sided printing requires two steps of making a plate and discharging each of the front and back sides, resulting in a problem of time loss and a lot of master used as a base paper, resulting in high costs. In view of this, a stencil printing apparatus capable of simultaneously printing both sides of a single apparatus without manual refeeding has been proposed in the following documents.

  The stencil printing apparatus described in Patent Document 1 is a type that performs two-sided printing with a two-pass one-drum, has a paper discharge tray that stocks single-sided printed paper, and reprints the single-sided printed paper from this paper discharge tray. Double-sided printing is performed by feeding and re-pressing the drum. In the case of the stencil printing apparatus described in Patent Document 1, since double-sided printing is performed in two passes, it is necessary to make the plate and eject the plate two times on the front and back sides.

  The stencil printing apparatus described in Patent Document 2 is a type that performs double-sided printing with two drums, and feeds printing paper between two drums facing each other, and makes a master plate-making image wound around each drum. Are printed on both sides of the printing paper. In the case of the stencil printing apparatus described in Patent Document 2, since there are two drums, a supply / discharge plate apparatus is required for each drum, so the mechanism is complicated, and the size of the machine is large and expensive.

  The stencil printing apparatus described in Patent Document 3 is a type capable of performing double-sided printing with one drum per pass, and prints an image of the front side area by dividing the printing area of one drum into two parts for the front side and the back side. Printing is directly performed on the front side of the paper, and the image on the back side is temporarily transferred to a press roller serving as a printing pressure member and printed on the back side of the printing paper. In the case of the stencil printing apparatus described in Patent Document 3, in order to transfer the image transferred to the press roller to the paper again, it is transferred to the printing paper for the second time via the front side image transferred directly from the master and the press roller. A density difference occurs in the back side image.

  The stencil printing apparatus described in Patent Document 4 is a type that performs two-sided printing with two passes and one drum, divides the printing area of one drum into two parts for the front side and the back side, and reverses the printing paper printed on one side. A reversing device is provided, and double-sided printing is performed by feeding a printing sheet printed on one side to the drum again by the reversing device. In the case of the stencil printing apparatus described in Patent Document 4, two ink supply devices per drum and press rollers facing each of them are required, and the mechanism is complicated and expensive.

  The stencil printing apparatus described in Patent Document 5 solves the problems of Patent Documents 1 to 4, and employs a one-drum split printing simultaneous reversal type duplex printing system. The stencil printing apparatus includes a printing unit having a drum and a press roller around which a master for dividing and making two images is arranged, an auxiliary tray for temporarily storing surface-printed paper, and a printing unit on the auxiliary tray. A sheet re-feeding unit that re-feeds the surface-printed sheet toward the sheet, and a switching member that guides the sheet that has passed through the printing unit to either the auxiliary tray or the sheet discharge unit. During double-sided printing, the first sheet is fed from the paper feeding unit to the printing unit, one image is printed on the surface of the paper, and the printed paper (surface printed paper) is guided to the auxiliary tray by the switching member. Then, the second sheet is fed from the sheet feeding unit to the printing unit to print one image on the surface of the sheet, and the first sheet that is printed on one side by the sheet refeeding unit is re-fed to the printing unit. The other image is printed on the back side of the paper, and the first sheet is guided to the paper discharge unit by the switching member, and the second sheet (surface printed paper) is guided to the auxiliary tray 8. For this reason, it is possible to perform single-sided printing without using a useless master, obtain a printed matter with good image quality during double-sided printing, and further suppress an increase in installation space.

  In Patent Document 6, the feed density in the sub-scanning direction at the time of plate making can be changed, the master punching is independent without being connected to the main scanning direction and the sub-scanning direction, and is optimal for the set resolution in the sub-scanning direction. There has been proposed a stencil printing apparatus capable of obtaining a perforated state.

Japanese Patent No. 02880052 Japanese Patent Laid-Open No. 10-86498 JP-A-8-332768 JP 9-95035 A JP 2003-200355 A Japanese Patent No. 0296863

  As described above, various stencil printing apparatuses capable of duplex printing have been proposed. However, in any case, attention is not paid to the case where the original image is different during duplex printing. For example, in the stencil printing apparatus described in Patent Document 6, the feed density in the sub-scanning direction at the time of plate making is made variable, but the density cannot be set for each of the front image and the back image. For this reason, even if one original is a photographic image and the other is a text image, and it is desired to improve the reproducibility (printing quality) of one original on the photographic image side, it corresponds to the other original. The plate making area must also be made in a state where the feed density in the sub-scanning direction is increased. In that case, the image of the finished printed matter is that each of the front image and the back image is more reproducible than usual, but the time required for plate making specific to the stencil printing apparatus is increased on both the front and back images. It will be.

  The present invention adopts a configuration in which when a double-sided image is created by a double-sided printing apparatus, a feed density in the sub-scanning direction can be arbitrarily varied between plate-making areas corresponding to the front-side image and the back-side image. It is an object of the present invention to provide a stencil printing apparatus capable of providing a printed material suitable for characteristics and a double-sided image desired by a user.

  According to the first aspect of the present invention, main scanning is performed in a state where a heat-sensitive stencil master having at least a thermoplastic resin film is pressed by a platen roller against punching means having a large number of heating portions arranged in the main scanning direction. While the thermosensitive stencil master is moved by the master conveying means in the sub-scanning direction perpendicular to the direction, the heat generating portion is heated according to the image signal, and the thermoplastic resin film is selectively melted and perforated according to the image signal. A perforation pattern is formed, this heat-sensitive stencil master is wound around the outer peripheral surface of the printing drum, ink is supplied from the inside of the printing drum, and an ink image corresponding to the image signal is generated by ink that has oozed through the perforation pattern. In a stencil printing apparatus capable of duplex printing that prints on a printing paper, the resolution in the sub-scanning direction corresponds to the first document corresponding to the front image and the back image corresponding to the front image during duplex printing. It is characterized by having a sub-scanning direction resolution setting means to be set in each document.

  According to a second aspect of the present invention, in the stencil printing apparatus according to the first aspect of the present invention, the stencil printing apparatus has a perforation energy adjusting means for adjusting the perforation energy supplied to the heat generating portion of the perforating means to a predetermined energy, The dimension is set to be equal to or less than the length of the feed pitch of the heat-sensitive stencil master by the master conveying means corresponding to the highest resolution that can be set by the sub-scanning direction resolution setting means.

  According to a third aspect of the present invention, in the stencil printing apparatus according to the second aspect, the perforation energy adjusting means adjusts the perforation energy so as to be continuously applied to one image signal a plurality of times. Yes.

  According to a fourth aspect of the present invention, in the stencil printing apparatus according to the second aspect of the present invention, the perforation energy is set to be adjusted by changing the energization pulse width, and the resolution in the sub-scanning direction is When a relatively low resolution is set among the resolutions that can be set by the scanning direction resolution setting means, the perforation energy adjusting means is set corresponding to a relatively high resolution for one image signal. It is characterized in that the perforating energy is adjusted so that an energization pulse having an energization pulse width longer than the energization pulse width is applied once.

  According to the first aspect of the present invention, during double-sided printing, the sub-scanning direction resolution of only one side of the printing paper is changed by the sub-scanning direction resolution setting means. As described above, it is possible to finish the plate-making of the area corresponding to the double-sided image without taking the plate-making time, and it is possible to achieve both the plate-making under the plate-making conditions according to the document image and the shortening of the plate-making time.

  According to the second aspect of the present invention, the signal of the sub-scanning direction resolution setting means in which the punching energy supplied to the individual heat generating portions of the punching means is set for the front and back images by the punching energy adjusting means. Accordingly, the size of the perforation in the sub-scanning direction of the heat-sensitive stencil master is controlled to an appropriate size by adjusting the predetermined energy in each plate-making area in accordance with the size in the sub-scanning direction of the heat generating portion. Is less than or equal to the length of the feed pitch corresponding to the highest resolution that can be set by the sub-scanning direction resolution setting means, so that each perforation is in the width scanning direction and the main scanning regardless of the set resolution in the sub-scanning direction. Since the independent perforation optimal for the resolution is performed without being connected in the scanning direction, an optimal printed image corresponding to the set resolution in the sub-scanning direction can be obtained.

  According to the third aspect of the present invention, in addition to the effect of the second aspect of the invention, the perforation energy adjusting means adjusts the perforation energy so that it is continuously applied to one image signal a plurality of times. As a result, the size of the perforation in the sub-scanning direction of the heat-sensitive stencil master is further controlled to an appropriate size, and it is possible to obtain an optimal print image that matches the set resolution in the sub-scanning direction. In addition, the perforation energy adjustment means adjusts the perforation energy so that it is continuously applied multiple times to one image signal, so that the heating element peak temperature of the perforation means is necessary for perforation of the heat-sensitive stencil master. The punching means can be punched to a desired size in the sub-scanning direction of the heat-sensitive stencil master without undue increase in temperature, that is, the threshold temperature of the heat-sensitive stencil master. The heat stress applied to the part can be reduced and reduced, and the life of the punching means can be improved.

  According to the invention described in claim 4, in addition to the effect of the invention described in claim 2, it is a case where the perforation energy is set to be adjusted by changing the energization pulse width, and the sub-scanning direction is set. When the resolution is set to a relatively low resolution among the resolutions that can be set by the sub-scanning direction resolution setting means, the perforation energy adjusting means supports a relatively high resolution for one image signal. By adjusting the perforation energy so as to apply an energization pulse having an energization pulse width longer than the energization pulse width set in this way, the size of the perforation in the sub-scanning direction of the heat-sensitive stencil master is more appropriate. The size of the image is controlled, and an optimal post-print image corresponding to the set resolution in the sub-scanning direction can be obtained. Further, the control method can be simplified as compared with the configuration of the second aspect.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a stencil printing apparatus capable of duplex printing to which the present invention is applied. In the drawing, the stencil printing apparatus 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 auxiliary tray 8, a refeed unit 9, a switching member 10, and the like. I have.

  The printing unit 2 is disposed substantially at the center of the apparatus main body 11 of the stencil printing apparatus, and includes a plate cylinder 12 serving as a drum and a press roller 13 serving as a printing pressure member. The plate cylinder 12 includes a pair of flanges (not shown) that are rotatably supported by a support shaft 14 that also serves as an ink supply pipe, a porous support plate (not shown) wound around the outer peripheral surface of each flange, and a porosity (not shown). It is mainly composed of a mesh screen (not shown) wound around the outer peripheral surface of the support plate. The plate cylinder 12 is configured to be rotationally driven by a plate cylinder driving unit 121 (see FIG. 3) and to be detachable from the apparatus main body 11. In this embodiment, the plate cylinder 12 has a size of an outer peripheral surface that can obtain a printed product of A3 size at the maximum during single-sided printing.

  An ink supply means 15 is disposed inside the plate cylinder 12. The ink supply means 15 includes a support shaft 14, an ink roller 16, and a doctor roller 17. The ink supplied from the support shaft 14 has a wedge-shaped cross section formed in a proximity portion between the ink roller 16 and the doctor roller 17. Ink is supplied to the inner peripheral surface of the plate cylinder 12 from the ink reservoir 18 formed by collecting in the space. A stage portion is formed on the outer peripheral surface of the plate cylinder 12, and a clamper 19 for holding the tip of the master is disposed on the outer peripheral surface of the plate cylinder 12. The clamper 19 is opened and closed by an opening / closing means (not shown) when the plate cylinder 12 is rotated to a predetermined position.

  A press roller 13 is disposed below the plate cylinder 12. The press roller 13 is 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. As shown in FIG. 2, the press roller 13 is rotatably supported by a pair of arm members 20 serving as press roller support members at both ends of the core portion 13a. Each arm member 20 having a substantially L shape is integrated by a swing shaft 21 attached to a portion near the bent portion, and the swing shaft 21 is rotatably supported by the apparatus main body 11. Yes. Between each arm member 20, in addition to the press roller 13, a refeed guide member 22, a refeed resist roller 23 as a refeed resist member, a refeed positioning member 24, a refeed transport member 25, a cleaning A cleaning roller 26 and a guide plate 27 are provided as members.

  As shown in FIG. 2, the refeed guide member 22 disposed in the vicinity of the right side of the press roller 13 is integrally provided on each of the support shafts 28a, 29a, and 30a, and the respective peripheral surfaces thereof are pressed by the press roller. A plurality of roller rollers 28, 29, 30 pressed against the peripheral surface of the paper 13, and a paper guide plate 31 formed in a curved shape for causing the paper P as a printing paper to follow the peripheral surface of the press roller 13; have. Each support shaft 28a, 29a, 30a is rotatably supported at each end by each arm member 20, and is urged toward the core portion 13a by urging means (not shown). Each of the rollers 28, 29, and 30 is integrally attached to the corresponding support shaft 28 a, 29 a, 30 a with a predetermined interval over substantially the entire width of the press roller 13. 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, 30, and both ends thereof are fixed to the arm members 20. Has been. 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 are formed.

  A re-feeding registration roller 23 is disposed below the press roller 13. The roller-shaped refeed resist roller 23 is rotatably supported by a support shaft 23a, and the support shaft 23a is attached to one end of a swing arm 32 as a refeed resist support member. The swinging arm 32 having a substantially square shape is supported by a support shaft 32a fixed between the arm members 20 so that the bent portion can swing freely. It is determined so that it is located at the approximate center in the width direction of the press roller 13 and is located in the middle of the position where each roller 30 is disposed. At the other end of the swing arm 32, a plunger 33a of a solenoid 33 attached to one arm member 20 via a bracket (not shown) and one end are fixed to the one arm member 20 and supported with respect to the swing arm 32. The other end of the tension spring 34 is attached to the shaft 32a to give a rotational biasing force in the counterclockwise direction in FIG. With this configuration, the re-feeding registration roller 23 occupies the press contact position indicated by the solid line in FIG. 2, which presses the peripheral surface against the peripheral surface of the press roller 13 with a predetermined press contact force when the solenoid 33 is operated. When the operation is released, the peripheral surface of the tension spring 34 is separated from the peripheral surface of the press roller 13 by the urging force of the tension spring 34 and occupies a separation position indicated by a two-dot chain line in FIG. The re-feeding resist contact / separation mechanism 40 is constituted by the solenoid 33 and the tension spring 34.

  A refeed positioning member 24 is disposed near the upper portion of the refeed resist roller 23. The re-feeding positioning member 24 is made of a plate material having an L-shaped cross section, and is formed so that the width thereof is substantially the same as the width of the press roller 13, and the bent end portion 24a faces upward. The portion is fixed to each arm member 20. The refeed positioning member 24 has a notch (not shown) for preventing the refeed registration roller 23 from colliding with the swing.

  A refeed conveyance member 25 is disposed below the press roller 13 and to the left of the refeed positioning member 24. The refeed conveyance member 25 includes a conveyance member main body 35, a driving roller 36, a driven roller 37, an endless belt 38, a suction fan 39, and the like, and an auxiliary tray 8 is integrally formed on the upper surface thereof.

  The transport member body 35, which is a casing formed so that its upper surface is opened and its width is slightly smaller than the interval between the arm members 20, is provided with bearings (not shown) on both the upstream and downstream sides of the sheet transport direction. Each bearing (not shown) rotatably supports the drive shaft 36a and the driven shaft 37a. Both ends of the drive shaft 36a penetrate both side surfaces of the conveying member main body 35, and both the penetrated both end portions are rotatably supported by a bearing member (not shown) provided in the apparatus main body 11. A drive gear (not shown) is attached to one end of the drive shaft 36 a, and the drive shaft 36 a is rotationally driven by a conveying member drive motor 122 provided in the apparatus main body 11. The driven shaft 37a is configured such that both ends thereof do not penetrate both side surfaces of the conveying member main body 35. Bosses 35a are integrally provided on both outer sides of the upstream end of the conveying member body 35 in the sheet conveying direction, and each boss 35a is fitted in a long hole (not shown) formed in each arm member 20, respectively. Has been. With this configuration, the transport member main body 35 is centered on the drive shaft 36a as the arm members 20 swing when the press roller 13 is brought into and out of contact with the plate cylinder 12 by a press roller contact / separation mechanism 55 described later. Rocking is possible.

  The plurality of roller-shaped drive rollers 36 are integrally attached to the drive shaft 36a, and predetermined intervals are provided between the drive rollers 36, respectively. A plurality of driven rollers 37 having the same shape as the drive roller 36 are integrally attached to the driven shaft 37 a at the same interval as each drive roller 36. An endless belt 38 having a plurality of holes (not shown) is stretched between the drive rollers 36 and the corresponding driven rollers 37 corresponding thereto with a predetermined tension. The endless belt 38 made of a frictional resistance member is moved in the direction indicated by the arrow in FIG. 2 when the drive shaft 36a is rotationally driven by the conveying member drive motor 122.

  A suction fan 39 is integrally attached to the lower surface of the conveying member main body 35, and the auxiliary tray 8 is integrally attached to the upper surface of the conveying member main body 35. The auxiliary tray 8 is formed with a plurality of openings (not shown) for allowing the endless belts 38 to face the sheet conveying surface, and a fence for receiving the sheet P being conveyed at the downstream end in the sheet conveying direction. 8a is integrally formed. A hole (not shown) is provided in the lower surface of the conveying member main body 35, which is a mounting surface of the suction fan 39, and the suction fan 39 is activated thereby to apply a negative pressure to the inside of the conveying member main body 35, which is a casing. The sheet P is sucked onto the upper surface of each endless belt 38 that is generated and moved. The suction force of the suction fan 39 and the frictional resistance force of the endless belt 38 are determined between the paper P and each endless belt 38 when the leading edge of the paper P comes into contact with the bent end 24a of the refeed positioning member 24. The strength is set so that slipping occurs. The re-feeding guide member 22, the re-feed registration roller 23, the re-feed positioning member 24, and the re-feed conveying member 25 constitute a re-feed unit 9.

  A cleaning roller 26 that cleans the peripheral surface of the press roller 13 is disposed in the vicinity of the press roller 13 and above the refeed conveyance member 25. The cleaning roller 26 having substantially the same width as the press roller 13 has at least the surface thereof made of a highly hygroscopic material such as Japanese paper or sponge, and integrally has a core portion 26a at the center thereof. . The cleaning roller 26 is rotatably supported by fitting the core portion 26a into a long hole (not shown) formed in each arm member 20, and a pressing roller is provided by a biasing means (not shown) provided in the long hole. The peripheral surface is constantly pressed against the peripheral surface of the press roller 13 with a predetermined pressing force. The cleaning roller 26 is about one-tenth of the peripheral speed of the press roller 13 in the same direction as the press roller 13 when the press roller 13 rotates by a cleaning roller driving means (not shown) provided on one arm member 20. It is rotationally driven at a peripheral speed.

  A guide plate 27 is disposed on the upper left side of the cleaning roller 26. Both ends of the guide plate 27, which is a plate material, are fixed to each arm member 20, and the sheet P pressed against the plate cylinder 12 by the press roller 13 does not touch the cleaning roller 26 and is attached to the auxiliary tray 8. Guide you to head. The guide plate 27 is disposed at a position close to the peripheral surfaces of the press roller 13 and the cleaning roller 26.

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

  In the vicinity of the left side of each cam follower 41, a multistage cam 43 having three cam plates 43A, 43B, 43C is disposed. Each cam plate 43A, 43B, 43C is fixed to a cam shaft 44 supported at both ends by the apparatus main body 11 and movably in the paper surface direction of FIG. The plate 43B, the cam plate 43A, and the cam plate 43C are arranged in this order. Each of the cam plates 43A, 43B, and 43C has a base portion that is a disc concentric with the cam shaft 44 and a convex portion having the same protruding amount. As shown in FIG. 3, the multistage cam 43 is provided with plate cylinder driving means via a drive gear 45 attached to the cam shaft 44 and a transmission gear 47 attached to a support shaft 46 rotatably supported by the apparatus body 11. The rotational force from 121 is transmitted, and it is rotated in the clockwise direction in FIG.

  The press roller 13 occupies a separation position shown in FIG. 2 where the circumferential surface is separated from the circumferential surface of the plate cylinder 12 when any convex portion of each of the cam plates 43A, 43B, 43C comes into contact with the cam follower 41. When the contact between any of the convex portions and the cam follower 41 is released, the peripheral surface occupies the press contact position shown in FIG. 3 where the peripheral surface presses the peripheral surface of the plate cylinder 12 by the urging force of the printing pressure spring 42. Each of the cam plates 43A, 43B, and 43C is configured so that the base and the cam follower 41 do not come into contact when the press roller 13 occupies the press contact position. The shape of the convex portions of the cam plates 43A, 43B, and 43C is such that the contact range between the press roller 13 and the plate cylinder 12 is a range in which all of the front surface region, the intermediate region, and the back surface region shown in FIG. Thus, the cam plate 43B is formed so as to be in the same range as the surface region, and the cam plate 43C is formed so as to be in the combined range of the downstream portion of the surface region, the intermediate region, and the back surface region. Further, the interval between the cam plates 43A, 43B, 43C is set to be sufficiently larger than the plate thickness of the arm member 20.

  In FIG. 2, press roller locking means (not shown) that prohibits the swinging of each arm member 20 in a state where the press roller 13 occupies the separated position is disposed near the right side of each arm member 20. The press roller locking means (not shown) has a solenoid (not shown), and the state of holding each arm member 20 and the state of releasing the holding are selectively switched by switching on and off the solenoid (not shown). A solenoid (not shown) is operated in a state where the cam follower 41 is in contact with any one of the convex portions of the cam plates 43A, 43B, and 43C.

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

  The roller 48 b is disposed between the discs 44 a and 44 b that are fixed to each other in the middle of the cam shaft 44, and the cam follower 48 c has its peripheral surface brought into contact with the peripheral surface of the step cam 49 by the biasing force of the tension spring 50. It is in contact. The interval between the discs 44a and 44b is set to be slightly larger than the diameter of the roller 48b.

  The step cam 49 has three cam portions 49 a, 49 b, 49 c on its peripheral surface, and is fixed to a support shaft 51 that is rotatably supported by the apparatus main body 11. A gear 54 that meshes with a gear 53 attached to an output shaft of a stepping motor 52 attached to the apparatus main body 11 is attached to the support shaft 51, and the step cam 49 is moved by an arrow in FIG. It is rotationally driven in the direction. With this configuration, when the stepping motor 52 is actuated to rotate the step cam 49, the moving arm 48 swings about the support shaft 48a, and the roller 48b pushes the disk 44a or the disk 44b so that the camshaft 44 is illustrated. 4 in the left-right direction.

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

  The above-described cam follower 41, the printing pressure spring 42, the multistage cam 43, the press roller locking means (not shown), the moving arm 48, and the step cam 49 constitute a press roller contact / separation mechanism 55. By the operation, the press roller 13 selectively occupies the separated position shown in FIG. 2 and the press contact position shown in FIG.

  As shown in FIG. 1, a switching member 10 that switches the transport path of the paper P is disposed on the transport 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 member 10 made of a plate material having substantially the same width as that of the plate cylinder 12 and the press roller 13 is rotatably supported on the downstream end thereof in the paper transport direction so as to be coaxial with the driven roller 88, and is shown in FIG. As a result of the operation of 123, the upstream end portion in the sheet conveying direction formed with an acute cross section is selectively positioned at a first position indicated by reference numeral 10a and a second position indicated by reference numeral 10b in FIG. When the switching member 10 occupies the first position 10a, the tip of the switching member 10 is located close to the peripheral surface of the press roller 13 and does not interfere with the clamper 19 on the plate cylinder 12, and occupies the second position 10b. The tip is placed at a position close to the peripheral surface of the plate cylinder 12. The paper P 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 10a, and the switching member 10 moves to the second position 10b. When occupied, it is guided to the auxiliary tray 8 through the space between the guide plate 27 and the guide plate 56 fixed to the apparatus main body 11.

  A plate making unit 3 is disposed in the upper right part of the apparatus main body 11. The plate making unit 3 includes a master holding member 57, a platen roller 58, a thermal head 59 as a punching unit, a cutting unit 60, a master stock unit 61, a tension roller pair 62, a reverse roller pair 63, and the like. The plate making unit 3 generates a plurality of heat generating elements which are heat generating portions of the thermal head 59 according to the image signal, and selectively melts and punches a thermoplastic resin film of the master 64 described later to form a punching pattern according to the image signal. The divided master-made master 65 having the first plate-making image 65A and the second plate-making image 65B as shown in FIG. 4, or the first plate-making image 65A and the second plate-making image 65B as shown in FIG. The master-making master 66 having the third plate-making image 66A having the image amount area for two sides is made. The first plate-making image 65A is formed at a position corresponding to the front surface region shown in FIG. 1 when the divided plate-making master 65 is wound on the outer peripheral surface of the plate cylinder 12, and the second plate-making image 65B is a back surface region. And corresponding positions.

  In the stencil printing, the master image such as the divided master plate 65 or the master plate master 66 is directly transferred and printed on the paper P, so that the image on the master is a mirror image as shown in FIGS. 4 and 5 are views in which the state wound around the plate cylinder 12 is developed and viewed from the film surface.

  The master holding members 57 are respectively provided on a pair of side plates (not shown) of the apparatus main body 11 and rotatably and detachably support both ends of a core portion 64b of a master roll 64a formed by winding the master 64 in a roll shape. ing. As the master 64, a thickness of 40 μm obtained by bonding a thermoplastic resin film having a thickness of 1.6 μm on a Japanese paper as a porous support is used.

  A platen roller 58 provided on the left side of the master holding member 57 is rotatably supported on a side plate (not shown) of the apparatus main body 11 and is rotationally driven by a stepping motor 124B serving as a master feed motor constituting the master transport unit 224. Is done.

As shown in FIG. 7, the master transport unit 224 has a master feed motor 124B and a master feed motor drive circuit 124A. The master feed motor 124B is connected to a master feed motor drive circuit 124A, and the master feed motor drive circuit 124A is connected to a microcomputer 160 serving as control means. The master feed motor 124B is driven when a drive command is issued from the microcomputer 160 to the master feed motor drive circuit 124A, and moves the master 64 in the sub-scanning direction orthogonal to the main scanning direction that is the paper width direction.
The master feed motor 124B is a stepping motor and is driven to rotate intermittently. Therefore, the heat-sensitive stencil master 64 is moved in the sub-scanning direction with a predetermined feed pitch by the master feed motor 124B via the platen roller 58.

  A thermal head 59 having a large number of minute heating elements arranged below the platen roller 58 and arranged in the main scanning direction is attached to a side plate (not shown) of the apparatus main body 11 and is attached with a biasing means (not shown). The surface of the heating element is pressed against the platen roller 58 by force. The thermal head 59 has a resolution of 300 DPI (dot / inch) in the main scanning direction, and a so-called rectangular heating element is used. Here, in order to explain the adjustment contents of the drilling energy supplied to the individual heat generating portions of the thermal head 59, the detailed configuration and operation of the heat generating portion in the thermal head 59 will be described first.

  In the stencil printing apparatus, the image density of the printed image is determined by the amount of ink that oozes from the master 64. The amount of ink that oozes from the master 64 is proportional to the opening area of the individual minute perforations that form the perforation pattern formed on the master 64, that is, the size of the perforations. The size of the perforations is proportional to the perforation energy corresponding to the temperature of each heat generating part of the thermal head. Therefore, the size of the perforation of the perforation pattern for obtaining an optimal printed image can be determined by adjusting the perforation energy corresponding to the temperature of each heat generating portion of the thermal head.

  Next, with reference to FIG. 9, a description will be given of the relation between the perforation energy supplied to each heat generating portion of the thermal head (temperature of each heat generating portion of the thermal head) and the size of the perforation of the perforation pattern. . Now, referring to FIGS. 9A-3 and 9B-3, these drawings show the structure of a minute heat generating portion in the thermal head 59 in a sectional view. A portion denoted by reference numeral 1A represents a heating element made of a thin layer of a high electrical resistance material, a portion denoted by reference numeral 1B represents a lead electrode, and a portion denoted by reference numeral 1C represents a protective film.

  The heating element 1A is formed on a substrate (a hatched portion). When a voltage is applied between the lead electrodes 1B, a current flows through the heating element 1A between the lead electrodes 1B, and the heating element 1A at the energized portion generates heat due to Joule heat. In the thermal head 59, such minute heat generating portions are arranged close to each other at a constant pitch in the direction orthogonal to the paper surface of FIGS. 9A-3 and 9B-3, that is, in the main scanning direction. The master 64 forms a perforation pattern by melt perforation while being conveyed in the left-right direction of FIGS. 9A-3 and 9B-3, that is, in the sub-scanning direction.

  As shown in FIG. 9B-4, the size of the heating element 1A of the thermal head 59 is 50 μm in the main scanning direction S and 40 μm in the sub-scanning direction F. The size of the thermal head 59 in the heating element 1A in the sub-scanning direction F is a length of a feed pitch of 63.5 μm / line (line) corresponding to 400 DPI which is the highest resolution that can be set with the density setting key 112 shown in FIG. It is set as follows.

  In addition to the above, the heat generating element of the thermal head is of a heat concentration type (the central portion of the heat generating element 1a is formed with a narrow width, the current density is increased in this portion, and heat generation is concentrated on this portion). In this case, as shown in FIG. 9 (a-5), the total length of the heating element portion in the sub-scanning direction F is 50 μm, the length of the heat generation concentrated portion in the same direction is 10 μm, and the heat generation in the main scanning direction S. The whole body part has a width of 50 μm, and the heat generation concentrated part in the same direction has a width of 15 μm.

  When drilling energy is supplied to the heat generating portion in the form of electrical energy, this energy is converted into heat energy by the heating element 1A, and the temperature of the master 64 in contact with the protective film 1C rises. The temperature distribution at this time is a mountain-shaped distribution such as a curve Tα shown in FIG. 9A-2 and a curve Tβ shown in FIG. 9B-2. As is easily understood, FIG. 9A-2 shows a case where the drilling energy supplied to the heat generating portion is relatively small, and FIG. 9B-2 shows that the drilling energy is relatively large. Is the case.

  A straight line indicated by a symbol D in the figure is a “threshold temperature” at which the thermoplastic resin film of the master 64 is melt-pierced, and the master 64 has a figure corresponding to the magnitude of the drilling energy supplied to the heat generating portion. Small perforations h as shown in FIG. 9 (a-1) or large perforations h as shown in FIG. 9 (b-1) are melted and perforated. In this way, the size of the perforation as one unit of the perforation pattern formed in the master 64 can be controlled by the perforation energy supplied to the individual heat generating portions of the thermal head 59, and perforation for obtaining an appropriate printed image. The energy value can be determined experimentally. This situation is the same whether the heat generating portion is rectangular or heat-concentrated.

  As described above, the perforating energy may be adjusted by changing the current value flowing to each heat generating portion or the voltage value applied to each heat generating portion in accordance with the image signal. This is performed by changing the energization pulse width to the heating element 1A of the head 59.

  As shown in FIG. 7, the thermal head 59 is connected to a thermal head drive circuit 124C. The thermal head drive circuit 124C is connected to the microcomputer 160, and the energization pulse width is set by the microcomputer 160. A composite circuit 140 and a power source 141 are connected to the thermal head drive circuit 124C. The composite circuit 140 changes the input digital image signal to an image data signal and outputs it to the thermal head drive circuit. The power source 141 is connected to the thermal head drive circuit 124C, and the thermal energy is supplied to the individual heat generation portions of the thermal head 59 through the thermal head drive circuit 124C. Supply. The thermal head drive circuit 124C selectively generates heat from the heating element of the thermal head 59 that comes into contact with the thermoplastic resin film surface of the master 64 in accordance with an image data signal that is an image signal, and heat fusion drilling is performed on the master 64. Perform plate making. In this embodiment, the plate making driving means 124 is constituted by the master conveying means 224 and the thermal head driving circuit 124C.

  As shown in FIG. 1, a known cutting means 60 for cutting the master 64 is disposed on the left side of the platen roller 58 and the thermal head 59. A master stock section 61 is disposed below the cutting means 60 on the downstream side in the master conveyance direction. The master stock section 61 that is a space for temporarily storing the divided master-making master 65 or the master-making master 66 is partitioned by a plurality of plate members, and a suction fan (not shown) is arranged at the innermost part. It is installed. When this suction fan is operated, a negative pressure is generated inside the master stock portion 61 which is a sealed space, and the divided master-making master 65 or the master-making master 66 which has been transported after plate-making is stored in the master stock portion 61. It is stored towards the innermost part. A tension roller pair 62 is disposed at a portion between the cutting means 60 and the master stock portion 61. A reverse roller pair 63 is disposed downstream of the master stock unit 61 in the master conveyance direction. The rollers on one side of the tension roller pair 62 and the reverse roller pair 63 are rotated by a drive motor (not shown) to feed the master in the master stock unit 61 toward the plate cylinder 12.

  The digital image signal that is the source of the image on the master is formed by reading an original with the image reading unit 7 disposed on the upper part of the apparatus main body 11, and the stencil printing apparatus is connected to an external processing apparatus such as a personal computer. In some cases, it is formed by the output of a digital manuscript created on a computer.

  As shown in FIG. 1, the image reading unit 7 reads the documents 91A and 91B indicated by broken lines. That is, each document placed on the document placement table 92 is subjected to exposure reading while being conveyed in the direction of arrow Y1 by the rotation of the separation roller 93, the front document conveyance roller pair 94, and the rear document conveyance roller pair 95, respectively. . At this time, when there are a large number of originals, only the lowermost original is conveyed by the action of the separating blade 96. One roller of the rear document transport roller pair 95 is driven to rotate by a document transport roller motor 128. The front document transport roller pair 94 is rotationally driven in conjunction with the drive of the rear document transport roller pair 95. When reading the images of the originals 91A and 91B, the reflected light from the surface of the original illuminated by the fluorescent lamp 99 as the light source is reflected by the mirror 98 while being conveyed on the contact glass 97 as the image reading means, and passes through the lens 100. , By being incident on an image sensor 101 composed of a CCD (charge coupled device) or the like. The document from which the image has been read is discharged onto a document tray 80 (not shown). The electrical signal photoelectrically converted by the image sensor 101 is input to an analog / digital (A / D) conversion board (not shown) in the apparatus body cabinet 50 and converted into a digital image signal. The digital image signal is stored in the image memory 135 and transmitted to the composite circuit 140. As shown in FIG. 7, the document transport roller motor 128 is connected to a document transport roller motor drive circuit 129 and constitutes a document transport drive means 130.

  A sheet feeding unit 4 is disposed below the plate making unit 3. The paper feed unit 4 includes a paper feed tray 67, a paper feed roller 68, a separation roller 69, a separation pad 70, a registration roller pair 71, and the like. A paper feed tray 67 on which a large number of sheets P can be stacked is supported by the apparatus main body 11 so as to be movable up and down, and is moved up and down by a paper feed driving means 125 (see FIG. 6) including a lifting means. A pair of side fences 72 supported by a rail member (not shown) so as to be movable in the paper width direction perpendicular to the paper transport direction are provided on the upper surface of the paper feed tray 67 on which A3 size paper P can be placed vertically. . On the free end side of the paper feed tray 67, a plurality of paper size detection sensors 73 for detecting the size of the stacked paper P are provided. The paper P has a paper size adapted to the size of the first image area 4 and the second image area 5. That is, when the maximum print size at the time of single-sided printing is A3 size, the maximum print size at the time of double-sided printing is roughly A4 size, and the maximum sheet passing paper is also A4. The paper passing direction is the paper passing direction.

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

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

  A registration roller pair 71 is disposed on the left side of the separation roller 69 and the separation pad 70. The registration roller pair 71 including the driving roller 71a and the driven roller 71b transmits the rotational driving force from the plate cylinder driving unit 121 by a driving force transmitting unit (not shown) such as a gear or a cam, so that the driving roller 71a is connected to the plate cylinder. 12, the paper P is fed toward the printing unit 2 at a predetermined timing by a driven roller 71 b that rotates at a predetermined timing in synchronization with the driven roller 71 and is in pressure contact with the driving roller 71 a.

  A plate discharging unit 5 is disposed on the upper left side of the printing unit 2. 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, and the like. The upper plate removal member 74 has a drive roller 78, a driven roller 79, an endless belt 80, etc., and the endless belt is driven by the drive roller 78 being rotated in the clockwise direction in the drawing by the plate discharge drive means 126 (see FIG. 6). 80 moves in the direction of the arrow in FIG. The lower plate removing member 75 includes a driving roller 81, a driven roller 82, an endless belt 83, and the like, and transmits the driving force of the plate discharging driving means 126 that rotationally drives the driving roller 78 by a driving force transmitting means (not shown) such as a gear or a belt. As a result, the drive roller 81 is rotationally driven in the counterclockwise direction in the figure, whereby the endless belt 83 moves in the arrow direction in FIG. Further, the lower plate removing member 75 is movably provided by a moving means (not shown) included in the plate discharging driving means 126, and an endless belt 83 located on the outer peripheral surface of the driven roller 82 is located at the position shown in the figure. It selectively occupies a position in contact with the outer peripheral surface.

  A plate removal box 76 for storing a used master therein is detachably attached to the apparatus main body 11. A compression plate 77 for pushing the used master carried by the upper plate removal member 74 and the lower plate removal member 75 into the plate release box 76 is supported by the apparatus main body 11 so as to be movable up and down, and is included in the plate discharge drive means 126. It is moved up and down by the lifting means that does not.

  A paper discharge unit 6 is disposed below the plate discharge unit 5. The paper discharge unit 6 includes an air knife device 150, a peeling claw 84, a paper discharge conveying member 85, a paper discharge tray 86, and the like. A plurality of peeling claws 84 are arranged in the width direction of the plate cylinder 12, and are respectively integrally attached to a support shaft that is swingably supported by the apparatus main body 11. The plurality of peeling claws 84 are swung by a claw rocking means (not shown), and the tips of the peeling claws 84 are located close to the peripheral surface of the plate cylinder 12 and the tips of the plates are avoided in order to avoid obstacles such as the clamper 19. It selectively occupies a position away from the outer peripheral surface of the trunk 12. The claw swinging means (not shown) transmits the driving force from the plate cylinder driving means 121 shown in FIG. 6 by the driving force transmission means (not shown), and swings the peeling claw 84 in synchronization with the rotation of the plate cylinder 12. The air knife device 150 is for assisting the peeling of the paper P by the peeling claw 84, and is used to guide the blower fan 151 and the air emitted from the fan 151 to the plate cylinder 12 near the paper discharge claw 84 in a thin layer. And a duct 152.

A paper discharge conveying member 85 disposed below the peeling claw 84 and to the left of the switching member 10 includes a driving roller 87, a driven roller 88, an endless belt 89, a suction fan 90, and the like. A plurality of roller-shaped drive rollers 87 are attached to a support shaft (not shown) rotatably supported on a unit side plate (not shown) at a predetermined interval, and each is integrally driven to rotate by a paper discharge driving means 127 (see FIG. 6). Is done. A plurality of driven rollers 88 are also provided on a support shaft (not shown) rotatably supported on the same side plate at equal intervals with each drive roller 87, and each drive roller 87 and each corresponding driven roller 88 corresponding to this have a plurality of holes. The endless belts 89 having the above are stretched over each other. A suction fan 90 is disposed below the driving roller 87, the driven roller 88, and the endless belt 89. The paper discharge conveying member 85 sucks the paper P onto each endless belt 89 by the suction force of the suction fan 90, and transports the paper P in the direction of the arrow in FIG.
A paper discharge tray 86 on which the paper P conveyed by the paper discharge conveyance member 85 is stacked is provided with one end fence 91 movable in the paper conveyance direction and a pair of side fences 92 movable in the paper width direction. And have.

  As shown in FIG. 1, a dog 133 serving as a phase timing detection plate is attached to the outer surface of a flange (not shown) constituting the plate cylinder 12, and a photo attached to the apparatus main body 11 near the periphery of the plate cylinder 12. A home position sensor 134 composed of an interrupter is provided. The home position sensor 134 detects the dog 133 when the plate cylinder 12 occupies a position where the clamper 19 faces the press roller 13 and outputs a phase timing signal to the microcomputer 160.

  FIG. 8 shows the operation panel 103 of the duplex printing apparatus. In the figure, an operation panel 103 provided on the upper front surface of the apparatus main body 11 has a start key 104, a stop key 105, a ten key 106, a paper size setting key 109, a double-sided printing key 110, a single-sided printing key 111, a secondary key on its upper surface. It has a density setting key 112 as scanning direction resolution setting means, display units 113, 114, 115 composed of LEDs, a display device 116 composed of an LCD, and the like.

  The start key 104 is pressed when the duplex printing apparatus performs the plate making operation and the printing operation. When the start key 104 is pressed, the plate making operation is performed after the plate discharging operation and the document reading operation are performed. Operation and printing operation are performed, and the double-sided printing apparatus enters a print standby state. A stop key 104 is pressed to stop the operation of the duplex printing apparatus, and a numeric key 106 is pressed to input a numerical value such as the number of prints. The paper size setting key 109 is pressed when an arbitrary paper size is input, and the paper size input with the paper size setting key 109 has priority over the paper size detected by the paper size detection sensor 73. The double-sided printing key 110 is pressed before the start key 104 is pressed when the double-sided printing apparatus performs a double-sided printing operation. When the double-sided printing key 110 is pressed, the LED 113 disposed in the vicinity thereof is lit to prompt the operator. It is displayed that the printer is in the duplex printing mode. The single-sided printing key 111 is pressed before the start key 104 is pressed when the double-sided printing apparatus performs a single-sided printing operation, and when the single-sided printing key 111 is pressed, the LED 114 disposed in the vicinity thereof is lit to give the operator one-sided printing. The print mode is displayed. In the duplex printing apparatus, the LED 114 is lit in the initial state, and the single-sided printing mode is set.

  The density setting key 112 has the same function as the fine mode setting key in a copying machine or the like. In order to set the resolution in the sub-scanning direction of the ink image on the printing paper P, the density setting key 112 is manually set to a desired resolution. Can be entered and set arbitrarily. In this embodiment, the resolution in the sub-scanning direction is normally set to 300 DPI (dots / inch), and the density setting key 112 is operated to increase the resolution in the sub-scanning direction to 400 DPI (dots / inch). It can be set by switching to. The density setting key 112 is pressed before the start key 104 is pressed when changing the feed density in the sub-scanning direction of the master, and when the density setting key 112 is pressed, the LED 115 arranged in the vicinity thereof lights up. The operator is in the high density mode. When this key is operated, a sub-scanning direction resolution setting signal is transmitted to the microcomputer 160 as shown in FIG. The display device 116 functions as a display function and a touch panel switch. When the double-sided printing key 110 and the density setting key 112 are pressed, sub-scanning of the plate-making area corresponding to either the front side or the back side in the double-sided printing mode is performed. An indication of whether or not to change the direction feed density appears, and switches 117 and 118 for selecting the front surface or the back surface are displayed.

  FIG. 6 shows a block diagram of a control system used in the duplex printing apparatus. In the figure, a microcomputer 160 has a CPU 161, a ROM 162, and a RAM 163 inside, and is provided inside the apparatus main body 11.

  The CPU 161 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 162. The drive unit provided in the unit 5, the paper discharge unit 6 and the image reading unit 7, the refeed resist contact / separation mechanism 40 provided in the refeed unit 9, the conveying member drive motor 122, and the switching member 10 are operated. The operation of the solenoid 123 is controlled to control the operation of the entire duplex printing apparatus 1. The ROM 162 stores an operation program for the entire duplex printing apparatus, and this operation program is appropriately called by the CPU 161. The RAM 163 has a function of temporarily storing calculation results of the CPU 161, 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 microcomputer 160 uses the phase timing signal from the home position sensor 134 and the rotation pulse signal generated every time the plate cylinder driving unit 121 rotates by a certain angle to determine the rotational phase position (timing) of the plate cylinder 12 in real time. Detect and recognize. When the density setting key 112 is operated and the switch 117 or 118 is operated to select a high resolution image surface in the duplex printing mode, the microcomputer 160 selects the master feed motor drive circuit 124A and the thermal head. High-density signals are transmitted to the drive circuit 124C and the document transport roller motor drive circuit 129, respectively, and the amount of heat generated by the master feed motor 124B and the thermal head 59 and the drive of the document transport roller motor 128 are controlled.

  Based on the output signal of the density setting key 112, the microcomputer 160 controls the master feed motor 124B to change the feed pitch corresponding to the set resolution in the sub-scanning direction, and the output signal of the density setting key 112. And the second drive control means for controlling the document conveying roller motor 128 so as to change the feed pitch corresponding to the set resolution in the sub-scanning direction, and the thermal head according to the output signal of the density setting key 112 It has various functions of drilling energy adjusting means for adjusting the drilling energy supplied to 59 individual heat generating parts to predetermined energy.

  In the ROM 162 of the microcomputer 160, relational data for setting a feed pitch corresponding to the set resolution in the sub-scanning direction, a program for energy adjustment, and an optimum according to the set resolution in the sub-scanning direction The relation data of the energization pulse width corresponding to the drilling energy for forming a drill having a large size is experimentally determined and stored in advance.

  The operation of the stencil printing apparatus having such a configuration will be described. In this embodiment, two originals 91A and 91B are set on the mounting table 92, and the original 91A is a front side original that is a first original, and the original 91B is a back side original that is a second original. When the operator inputs the number of prints using the numeric keypad 106 and presses the duplex printing key 110, the plate making process for duplex printing in FIG. 10 starts. In step S1, it is determined whether or not the duplex printing mode is set. If the operator depresses the duplex printing key 110, the duplex printing mode is set, the LED 113 is turned on, and the process proceeds to step S2. In step S2, it is determined whether or not the descending density in the sub-scanning direction is high. If the density setting key 112 is not operated, it is determined that the printing density is normal, and the process proceeds to step S7. In step S7, it is determined that the start key 104 has been pressed. When the start key is pressed, the front plate making and the back plate making are executed in steps S8 and S9, and this process ends.

  When the plate making in steps S8 and S9 is a plate making with a normal density, the image reading unit 7 drives the original conveying roller motor 128 at a normal speed so that the original image of the first sheet (first original 91A) is normal. Read at speed. The read document image is stored in the image memory 135 as a digital image signal of the surface image. When the reading operation of the first document 91A is completed and the digital image signal is stored in the image memory 135, the reading operation of the second document (second document 91B) is continuously performed. Done at a similar speed. The read document image is stored in the image memory 135 as a digital image signal of the back image.

  In parallel with the image reading operation for the first document 91A, the plate discharging unit 5 performs the plate discharging operation. The plate cylinder 12 from which the used master has been peeled off from the outer peripheral surface stops at the plate feeding standby position, and the clamper 19 is opened by an opening / closing means (not shown).

  In the plate making unit 3, the digital image signal stored in the memory 135 is imaged via a decoding circuit in order to form the first plate making image 65 </ b> A and the second plate making image 65 </ b> B on the thermoplastic resin film surface of the master 64. The data signal is transmitted to the thermal head driving circuit 124C. At the same time, the microcomputer 160 sends to the thermal head drive circuit 124C a signal for setting an energization pulse width for forming a hole having an optimum size according to the set resolution in the sub-scanning direction. In parallel with this, the microcomputer 160 sends a feed pitch setting signal to the master feed motor drive circuit 124A based on a preset sub-scanning direction feed density setting signal corresponding to the surface image, and the master feed motor. 124B is driven. As a result, the platen roller 58 is rotated and the heat-sensitive stencil master 64 is conveyed at a predetermined feed pitch and speed. Therefore, the first plate making image 65A and the second plate making image 65B are made at a normal density.

  If the density setting key 112 is operated, the high density mode is set in step S2, and the process proceeds to step S3. When the density setting key 112 is pressed while the duplex printing key 110 is pressed, the feed density in the sub-scanning direction of the plate making area corresponding to either the first document 91A or the second document 91B is displayed on the display device 116. Switches 117 and 118 for selecting whether or not to change are displayed. Then, when the switch 117 is operated to increase the density of the plate-making area corresponding to the surface image, that is, when the front-side feed density change is selected, in step S4, the density is higher than the normal density. A sub-scanning direction resolution setting signal is transmitted to the microcomputer 160 so as to obtain a density, and the master feed pitch and speed on the front side are changed. In step S5, the document feed pitch and speed for the first document 91A that is the front side document are changed from normal to high density, and in step S6, the energization pulse width setting for the thermal head drive circuit 124C is changed. The When the start key 104 is pressed in this state, the plate making unit 3 drives the master feed motor 124B and rotates the platen roller 58 to make a plate making image corresponding to the first document 91A at a high density, and heat sensitive. The stencil master 64 is conveyed at a predetermined feed pitch and speed for high density. In the thermal head drive circuit 124C, on the basis of the energization pulse width setting signal corresponding to each sub-scanning direction resolution setting signal, the energization pulse (thermal head drive signal) is generated by receiving power supply from the power source 141, and the thermal head. 59, the heat generating portions corresponding to the black pixels generate Joule heat, and the heat-sensitive stencil master 64 is melt punched. As a result, the first platemaking image 65A is made with high density. The second plate making image 65B is made at a normal density.

  If the switch 117 is operated and the front-side feed density change is not selected, the process proceeds to step S10 to determine whether or not the switch 118 is operated, that is, whether the back-side feed density change is selected. Is done. If the switch 118 is operated and the change of the feed density on the back side is selected, the process proceeds to step S11, and if not selected, the process returns to step S3. In step S11, a sub-scanning direction resolution setting signal is transmitted to the microcomputer 160 so as to obtain the highest settable resolution, and the master feed pitch and speed on the front side are changed. In step S12, the document feed pitch and speed for the second document 91B, which is the document on the back side, are changed from normal to high density. In step S13, the energization pulse width setting for the thermal head drive circuit 124C is changed. The

  When the start key 104 is pressed in this state, the plate making unit 3 drives the master feed motor 124B and rotates the platen roller 58 to make a plate making image corresponding to the second original 91B at a high density, and the heat sensitive. The stencil master 64 is transported at a predetermined feed pitch and speed for high density, and only the second plate-making image 65B is made at high density, and the second plate-making image 65B becomes the original on the back side that is made at normal density. The document feed pitch and speed for the second document 91B are changed from normal to high density, and in step S12, the energization pulse width setting for the thermal head drive circuit 124C is changed. When the start key is pressed in this state, in the plate making unit 3, the master feed motor 124B is driven to rotate the platen roller 58 so as to correspond to the normal density, and the plate making corresponding to the first original 91A has the normal density. The first plate-making image 65A having a normal density is made. After the first plate making image 65A is made, in order to make a plate making image corresponding to the second original 91B at a high density, the master feed motor 124B is driven to rotate the platen roller 58 and the heat sensitive stencil master 64 is used for high density. Are conveyed at a predetermined feed pitch and speed. In the thermal head drive circuit 124C, on the basis of the energization pulse width setting signal corresponding to each sub-scanning direction resolution setting signal, the energization pulse (thermal head drive signal) is generated by receiving power supply from the power source 141, and the thermal head. 59, the heat generating portions corresponding to the black pixels generate Joule heat, and the heat-sensitive stencil master 64 is melt punched. As a result, the second plate-making image 65B is made with high density, and the high-density second plate-making image 65B is made.

  In this embodiment, as shown in FIG. 4, plate making is performed such that a predetermined blank portion S is provided between the first plate making image 65A and the second plate making image 65B. The speed change of 128 is changed in the plate making time occurring between the blank portions S. The predetermined blank portion S is provided at a position corresponding to the intermediate region shown in FIG. 1 when the divided plate-making master 65 is wound on the outer peripheral surface of the plate cylinder 12.

  According to the stencil printing apparatus 1 of the present embodiment, during double-sided printing, the sub-scanning direction resolution of only one side of the printing paper is changed by the operation of the sub-scanning direction resolution setting means 117 and 118, so that only one side has high resolution. It is possible to finish plate making of areas corresponding to double-sided images without taking plate making time more than necessary, and to achieve both plate making under plate making conditions according to the original image and shortening of plate making time. it can.

  In this embodiment, the image reading unit 7 is of a type that conveys each document on the contact glass 97, but each document is placed on the contact glass 97 and the fluorescent lamp 99 and the mirror 98 are moved together. A scanning type may be used. In this case, the configuration of the document conveyance driving means 130 and the document conveyance rollers 94 and 95 shown in FIG. 7 is not necessary, and a drive motor and a drive circuit for moving the fluorescent lamp 99 and the mirror 98 are provided. Then, the microcomputer 160 may change the scanning pitch (scanning speed) corresponding to the feed pitch between the normal density and the high density that are density information.

  In this embodiment, each original is read by the image reading unit 7, and the plate making unit 3 performs the plate making operation on the heat-sensitive stencil master 64 based on the read digital image signal. If the digital image signal is input from the personal computer, the configuration of the document transport driving means 130 and the document transport rollers 94 and 95 shown in FIG. 7 may be omitted.

  The divided prepress master 65 on which the prepress images 65A and 65B are formed is stored in the master stock unit 61. When the plate discharging operation is completed and the duplex printing apparatus 1 is in the plate feed standby state, the reverse roller pair 63 is operated. It is conveyed toward the open clamper 19. Thereafter, the plate cylinder 12 is intermittently rotated, and the divided plate-making master 65 is wound around the plate cylinder 12. When all the two pieces of image data are sent from the image memory 135, the cutting means 60 is activated and the divided master-making master 65 is cut. The cut master plate 65 is pulled out of 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 stepping motor 52 shown in FIG. 3 operates to rotate the step cam 49 and press roller locking means (not shown) to bring the cam portion 49a into contact with the cam follower 48c. As a result, the moving arm 48 is swung around the support shaft 48a, and the cam shaft 44 is moved to a position where the cam plate 43B can be brought into contact with the cam follower 41. Is released.

  Thereafter, the paper feed roller 68, the separation roller 69, the drive rollers 36 and 87, and the suction fans 39 and 90 are respectively driven, and the plate cylinder 12 is driven at a low speed by the drive of the plate cylinder drive means 121. The first sheet P1 is pulled out from the sheet feed tray 67 and the leading end thereof is sandwiched between the registration roller pair 71. When the clamper 19 passes the position corresponding to the switching member 10, the solenoid 123 is actuated to position the switching member 10 at the second position, and then the divided plate-making master 65 wound on the plate cylinder 12 is moved. The drive roller 71a is rotationally driven at a predetermined timing when the leading end of the image area of the first plate-making image 65A in the direction of rotation of the plate cylinder reaches a position corresponding to the press roller 13, whereby the drawn paper P1 is extracted from the plate cylinder 12. And the press roller 13.

  The cam plate 43B moved to a position where it can come into contact with the cam follower 41 at the predetermined timing disengages its convex portion from the cam follower 41, and the press roller 13 presses the peripheral surface by the biasing force of the printing spring 42. Press contact with the outer peripheral surface of the body 12. As a result, the press roller 13, the paper P1, the first plate-making image 65A forming portion of the divided plate-making master 65, and the plate cylinder 12 are brought into pressure contact with each other, and the ink supplied to the inner peripheral surface of the plate cylinder 12 by the ink roller 16 The first plate-making image 65A is exuded after being filled in the porous support plate (not shown) and mesh screen (not shown) wound around the plate cylinder 12 and the porous support body of the divided plate-making master 65. The portion of the divided master-making master 65 where the first plate-making image 65A is formed is printed on the paper P1 through the punching portion.

  The sheet P1 on which the image corresponding to the first plate-making image 65A is printed on the surface by printing is peeled off from the divided plate-making master 65 on the outer peripheral surface of the plate cylinder by the tip of the switching member 10, The re-feeding means 9 is guided by the switching member 10 occupying the position 2. The sheet P 1 guided downward by the switching member 10 passes between the guide plates 27 and 56, has its tip abutted against the fence 8 a, and is placed on the auxiliary tray 8. The sheet P1 transported on the auxiliary tray 8 is transported in the direction of the arrow in FIG. 1 while being held on the endless belt 38 that rotates by the transport of the transport member drive motor 122 by the suction force generated by the drive of the suction fan 39. The front end (the rear end when the first plate-making image 65A is printed) is brought into contact with the bent end portion 24a. At this time, since slip occurs between the paper P1 and the endless belt 38, the paper P1 is stopped in a state where the leading end thereof is in contact with the bent end portion 24a. A sensor (not shown) is provided for detecting when the leading edge of the paper P1 comes into contact with the bent end 24a. When the sensor (not shown) detects the leading edge of the paper P1, the drive roller 36 and the suction fan 39 are operated. It is good also as a structure which stops.

  The plate cylinder 12 continues to rotate while the paper P1 is being guided on the auxiliary tray 8, and when the press roller 13 finishes contact with the surface area of the plate cylinder 12, the convex portion of the cam plate 43B becomes the cam follower 41. It occupies the separated position by contacting the Due to the function of the cam plate 43B, the back surface region of the plate cylinder 12 and the press roller 13 are not in pressure contact with each other in the absence of the paper P, and ink transfer to the peripheral surface of the press roller 13 can be prevented. At this time, a press roller locking means (not shown) is operated to hold the press roller 13 at the separated position, and then the stepping motor 52 is operated to rotate the step cam 49 to bring the cam portion 49b into contact with the cam follower 48c. As a result, the moving arm 48 is swung around the support shaft 48a, and the cam shaft 44 is moved to a position where the cam plate 43A can be brought into contact with the cam follower 41.

  Almost simultaneously with the above-described operation, the paper feed roller 68 and the separation roller 69 are driven, the second sheet P2 is drawn from the paper feed tray 67, and the leading end thereof is sandwiched between the registration roller pair 71. Then, the drive roller 71a is rotationally driven at a predetermined timing similar to that described above, and the drawn paper P2 is fed toward the space between the plate cylinder 12 and the press roller 13.

  In the press roller contact / separation mechanism 55, when the cam shaft 44 rotates to a position where the convex portion of the moved cam plate 43A can come into contact with the cam follower 41, the operation of the press roller locking means (not shown) is released. At this time, the plate cylinder 12 rotating in synchronization with the camshaft 44 occupies a position where the non-opening portion, which is a portion other than the front surface region, the back surface region, and the intermediate region, faces the press roller 13. Further, the solenoid 123 is operated until the surface region of the plate cylinder 12 passes through the portion facing the press roller 13 and the clamper 19 occupies the position corresponding to the switching member 10 again. It is displaced from the position to the first position.

  At a predetermined timing when the sheet P2 is fed by the registration roller pair 71, the cam plate 43A disengages the convex portion from the cam follower 41, so that the press roller 13 causes the printing cylinder to move its peripheral surface by the urging force of the printing spring 42. 12 is pressed against the outer peripheral surface. As a result, the press roller 13, the paper P2, the first plate-making image 65A forming portion of the divided plate-making master 65, 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 is the plate cylinder. The image is transferred to the paper P2 through the 12 openings, a porous support plate (not shown), a mesh screen (not shown), and a perforated portion of the first platemaking image 65A.

  The paper P2 on which an image corresponding to the first plate-making image 65A is printed is guided to the paper discharge conveyance member 85 by the switching member 10 occupying the first position, and from the front end portion thereof by the peeling claw 84. It is peeled off from the divided plate-making master 65 on the outer peripheral surface. The peeled paper P2 falls downward and is sent to the paper discharge conveying member 85 and then discharged onto the paper discharge tray 86.

  After the sheet P2 is fed by the registration roller pair 71, it is slightly earlier than the leading end of the image area of the second plate-making image 65B in the plate cylinder rotation direction of the divided plate-making master 65 reaches the position corresponding to the press roller 13. The solenoid 33 is actuated at a predetermined timing, which is the timing, and the swing arm 32 is swung in the clockwise direction in FIG. 2 about the support shaft 32a. As a result, the re-feeding registration roller 23 is swung from the separation position to the press-contact position, and the sheet P1 stopped with the leading end abutting against the bent end 24a abuts on the plate cylinder 12 and is driven to rotate. The press roller 13 is in contact with the peripheral surface.

  The paper P1 brought into contact with the peripheral surface of the press roller 13 by the re-feeding registration roller 23 is conveyed to the downstream side in the rotational direction by the rotational force of the press roller 13, and the paper guide plate 31 and the rollers 28, 29, The sheet 30 is conveyed toward the contact portion with the plate cylinder 12 while being in close contact with the peripheral surface of the press roller 13. At this time, an image corresponding to the first plate-making image 65A is printed on the surface of the paper P1, but since the paper P1 is in close contact with the peripheral surface of the press roller 13 by the action of the refeed guide member 22, once. The sheet P1 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. Then, after the rear end and the intermediate region of the paper P2 pass through the position corresponding to the press roller 13, the paper P1 is moved to the plate cylinder 12 and the press roller at the timing when the leading end of the back surface region reaches the position corresponding to the press roller 13. 13 is sent to the abutting part.

  As a result, the press roller 13, the paper P1, the second plate-making image 65B forming portion of the divided plate-making master 65, 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 is supplied to the plate cylinder. The second plate-making image 65B of the divided plate-making master 65 is formed by being transferred to the paper P1 through the 12 openings, the porous support plate (not shown) and the mesh screen (not shown), and the perforated portion of the second plate-making image 65B. The part is printed.

  The paper P1 on which the image corresponding to the first plate-making image 65A is printed on the front surface and the image corresponding to the second plate-making image 65B is printed on the back surface is transferred to the paper discharge conveyance member 85 by the switching member 10 occupying the first position. And the air sprayed from the air knife 152 and the action of the peeling claw 84 are peeled off from the divided master plate 65 on the outer peripheral surface of the plate cylinder by the action of the peeling claw 84. The peeled sheet P1 drops downward and is sent to the paper discharge conveying member 85 and then discharged onto the paper discharge tray 86. Thereby, the plate-making operation of the divided master-making master 65 is completed, and the printing operation is completed. Move on.

  At the time of printing, a predetermined blank portion S is provided between the first plate-making image 65A and the second plate-making image 65B of the divided plate-making master 65, and the divided plate-making master 65 is wound on the outer peripheral surface of the plate cylinder 12. Since the intermediate area is formed when the paper is loaded, it is possible to prevent the rear end of the paper P2 sent from the paper supply unit 4 and the front end of the paper P1 sent from the refeed means 9 from being overlapped. Can be used for easy printing. Further, when the paper P1 is fed again from the refeeding means 9, the ink from the paper P1 is retransferred to the surface of the press roller 13 by coming into contact with the printing surface of the paper P1. Since the surface has ink repellency and the cleaning roller 26 cleans the peripheral surface of the press roller 13, the amount of re-transferred ink from the paper P1 to the peripheral surface of the press roller 13 is reduced and from the peripheral surface of the press roller 13. The removal of the retransfer ink is promoted, and the retransfer of the ink from the press roller 13 to the back surface of the paper P can be prevented during the following printing.

  In the printing operation, the plate cylinder 12 is rotationally driven at the printing speed after the cam shaft 44 is moved to a position where the cam plate 43B can come into contact with the cam follower 41 as in the case of printing, and the switching member 10 is moved to the first position. 2 is positioned. After rotation of the plate cylinder 12 is started, the first sheet P1 is fed from the sheet feeding unit 4, and the fed sheet P1 is temporarily stopped by the registration roller pair 71 and then fed at the same timing as the trial printing. The The sheet P1 is pressed against the first plate-making image 65A of the divided plate-making master 65 by the press roller 13, whereby an image corresponding to the first plate-making image 65A is printed on the surface. The sheet P1 on which the image is printed is peeled and guided by the switching member 10 occupying the second position, conveyed onto the auxiliary tray 8, and stopped in a state where the leading end is in contact with the bent end 24a. .

  Thereafter, the press roller locking means (not shown) is operated to hold the press roller 13 at the separated position, and the cam shaft 44 is moved to a position where the cam plate 43A can come into contact with the cam follower 41. The operation of the press roller locking means is released. Almost simultaneously with this operation, the second sheet P2 is fed from the sheet feeding unit 4, and the sheet P2 is temporarily stopped by the registration roller pair 71 and then fed toward the printing unit 2 at the same timing as the sheet P1. Is done. The switching member 10 is positioned at the first position so as to avoid a collision with the clamper 19, and then is positioned again at the second position after passing the clamper 19.

  The fed paper P2 is pressed against the first plate-making image 65A of the divided plate-making master 65 by the press roller 13, and after the image corresponding to the first plate-making image 65A is printed on the surface, it occupies the second position. Stripping is guided by the switching member 10 and conveyed onto the auxiliary tray 8. At this time, the solenoid 33 is actuated at the same timing as the trial printing, and the paper P1 retained on the auxiliary tray 8 is conveyed to the printing unit 2 by the rotational force of the press roller 13. After the rear end of the sheet P2 passes through the contact portion between the plate cylinder 12 and the press roller 13, the sheet P1 passes through a position where the intermediate area of the plate cylinder 12 faces the press roller 13, and the back area is the press roller. 13 is sent to the abutting portion between the plate cylinder 12 and the press roller 13 at a timing facing the plate 13, and is pressed against the second plate-making image 65B of the divided plate-making master 65 by the press roller 13. An image corresponding to 65B is printed.

  During the above-described operation, the solenoid 123 is actuated immediately before the intermediate region of the plate cylinder 12 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, the rear end of the sheet P2 guided by the switching member 10 is guided onto the auxiliary tray 8 through a slight gap between the lower surface 10a of the switching member 10 and the peripheral surface of the press roller 13. Subsequently, the leading edge of the conveyed paper P <b> 1 is guided to the paper discharge conveying member 85 along the upper surface 10 b of the switching member 10. The paper P1 is peeled off from the divided master-making master 65 by the peeling claw 84, then transported by the paper discharge transport member 85, and discharged onto the paper discharge tray 86.

  The third sheet P3 is fed from the sheet feeding unit 4, and the sheet P3 is temporarily stopped by the registration roller pair 71 and then fed toward the printing unit 2 at the same timing as the sheet P1. The switching member 10 is positioned at the first position to avoid a collision with the clamper 19, and is positioned again at the second position after passing the clamper 19. The fed paper P3 is guided on the auxiliary tray 8 by the switching member 10 after an image corresponding to the first plate-making image 65A is printed on the surface. Then, the solenoid 33 is actuated at a predetermined timing, and the paper P2 stopped on the auxiliary tray 8 is conveyed to the printing unit 2. The sheet P2 is sent to the contact portion between the plate cylinder 12 and the press roller 13 at the same timing as the above-described sheet P1, and an image corresponding to the second plate-making image 65B is printed on the back surface thereof. The switching member 10 is displaced from the second position to the first position at the same timing as described above, and the rear end of the sheet P3 has a slight gap between the lower surface 10a of the switching member 10 and the peripheral surface of the press roller 13. It is guided on the auxiliary tray 8 through. Following this, the leading edge of the paper P2 conveyed from the auxiliary tray 8 is guided to the paper discharge conveying member 85 along the upper surface 10b of the switching member 10, and the paper P2 is divided by the plate-making master 65 by the peeling claw 84. After being further peeled off, the sheet is conveyed by the sheet discharge conveying member 85 and discharged onto the sheet discharge tray 86.

  Thereafter, the same printing operation as described above is performed up to the (N-1) th sheet. Then, after the Nth sheet PN is fed from the sheet feeding unit 4 and an image corresponding to the first plate-making image 65A is printed on the surface and guided onto the auxiliary tray 8, the (N-1) th sheet When an image corresponding to the second plate-making image is printed on the back surface of the sheet P (N-1) and discharged onto the sheet discharge tray 86, a press roller locking means (not shown) is activated to cause the press roller 13 to move. After the cam shaft 44 is moved to a position where the cam plate 43C can be brought into contact with the cam follower 41 while being held at the separated position, the operation of the press roller locking means (not shown) is released. At this time, the switching member 10 maintains the state of occupying the first position.

  Then, the cam follower 41 can be brought into contact with the cam follower 41 at the first timing earlier than the leading end of the image area of the second plate-making image 65B in the plate cylinder rotation direction of the divided plate-making master 65 reaches the position corresponding to the press roller 13. The cam plate 43 </ b> C moved to the position disengages the convex portion from the cam follower 41, and the press roller 13 presses the peripheral surface thereof against the outer peripheral surface of the plate cylinder 12 by the biasing force of the printing pressure spring 42. Thereafter, the solenoid 33 is actuated at a second timing slightly earlier than the leading edge of the image area of the second plate-making image 65B in the direction of rotation of the plate cylinder of the divided plate-making master 65 reaches the position corresponding to the press roller 13, and the oscillation is changed. The moving arm 32 is swung clockwise around the support shaft 32a in FIG. As a result, the re-feeding registration roller 23 is swung from the separation position to the press-contact position, and the sheet PN stopped with the leading end abutting against the bent end portion 24a abuts on the plate cylinder 12 and is driven to rotate. The press roller 13 is in contact with the peripheral surface.

  The sheet PN is sent to the contact portion between the plate cylinder 12 and the press roller 13 at the same timing as the sheet P1, and an image corresponding to the second plate-making image 65B is printed on the back surface thereof. The paper PN on which the image is printed is guided to the paper discharge conveyance member 85 along the upper surface 10b of the switching member 10, and is peeled off from the divided plate-making master 65 by the peeling claw 84 and then conveyed by the paper discharge conveyance member 85. The paper is discharged onto the paper discharge tray 86. Thereafter, the press roller 13 occupies the separated position by the convex portion of the cam plate 43 </ b> C coming into contact with the cam follower 41 when the contact with the back surface region of the plate cylinder 12 is finished. Due to the function of the cam plate 43C, the surface region of the plate cylinder 12 and the press roller 13 are not pressed against each other in the absence of the paper P, and ink transfer to the peripheral surface of the press roller 13 can be prevented. At this time, the press roller locking means (not shown) is actuated to hold the press roller 13 in the separated position, and then the plate cylinder 12 stops at the home position, and the duplex printing apparatus 1 finishes the printing operation and enters the print standby state again. Become.

  During the printing described above, a predetermined blank portion S is provided between the first plate-making image 65A and the second plate-making image 65B of the divided plate-making master 65, and the divided plate-making master 65 is placed on the outer peripheral surface of the plate cylinder 12. Since the intermediate region is formed when the paper is wound, it is possible to prevent the trailing edge of the paper P sent from the paper feeding unit 4 and the leading edge of the paper P sent from the refeeding means 9 from being overlapped, By switching the switching member 10, the paper P from the paper feeding unit 4 can be reliably conveyed to the auxiliary tray 8, and the paper P from the refeeding means 9 can be reliably conveyed to the paper discharge tray 86. Further, when the paper P is re-feeded from the re-feeding means 9, the ink from the paper P and the outer periphery of the plate cylinder are brought into contact with the printing surface of the paper P and the outer peripheral surface of the plate cylinder 12. Although the ink from the surface retransfers, 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 transfer ink is reduced and 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 can be prevented during the following printing.

  According to this double-sided printing apparatus 1, during single-sided printing, the platemaking unit 3 creates a platemaking master 66, winds it around the plate cylinder 12, feeds the paper P from the paper feed unit 4, and presses it. Since the roller 13 is pressed against the plate cylinder 12, single-sided printing can be performed in the same manner as in a normal stencil printing apparatus without wasting the master 64. At the time of duplex printing, the plate making unit 3 creates a divided plate-made master 65 and winds it on the plate cylinder 12, feeds the first sheet P 1 from the paper feed unit 4, and the surface is pressed by the press roller 13. After being brought into pressure contact with the cylinder 12, the sheet is discharged onto the auxiliary tray 8, and the second sheet P 2 is fed from the paper feeding unit 4, and this surface is pressed against the plate cylinder 12 with the press roller 13, and then the auxiliary tray 8. Since the first sheet P1 is reversely fed by the refeeding means 9 and the back surface is pressed against the plate cylinder 12 by the press roller 13 and then discharged onto the discharge tray 86. Both the front image and the back image printed on the paper P are formed by the ink transferred from the plate cylinder 12 by the press roller 13, and a good double-sided printed product can be obtained.

  Next, regarding the relationship between the energization pulse width setting method and the drilling state of the master 64 when the resolution in the sub-scanning direction is changed to 300 DPI and 400 DPI using the thermal head 59 having a resolution of 300 DPI in the main scanning direction, This will be described with reference to FIGS. 11 to 14, 15 and 16. The line cycle Th of the thermal head 59 is the same in each setting method.

  First, a case where the resolution in the sub-scanning direction F is set to 400 DPI in FIGS. 11 and 12 will be described. As shown in FIG. 12, the feed pitch Pf of the master 64 is 63.5 μm / line corresponding to the resolution 400 DPI in the sub-scanning direction F. As shown in FIG. 11A, when one energization pulse corresponding to the energization pulse width tp1 is applied to the heating element of the thermal head 59, the temperature rise characteristic of the heating element is as shown in FIG. Draw an approximately sawtooth wave-like curve to increase the temperature and decrease the temperature. As a result, the punching state of the master 64 is optimally adapted to a resolution of 400 DPI in the sub-scanning direction F without the perforations h being connected and punching in the sub-scanning direction F and the main scanning direction S, as shown in FIG. The perforation h is obtained.

  Next, a case where the resolution in the sub-scanning direction F is set to 300 DPI in FIGS. 13 and 14 will be described. As shown in FIG. 14, the feed pitch Pf of the master 64 is 84.7 μm / line corresponding to the resolution 300 DPI in the sub-scanning direction F. As shown in FIG. 13A, two continuous energization pulses corresponding to the energization pulse widths tp2 and tp4 are applied to the heating element of the thermal head 59 for one image signal. When two continuous energization pulses are applied in this way, the temperature rise characteristic of the heating element is increased in temperature by drawing two continuous sawtooth-like curves as shown in FIG. . Thereby, as shown in FIG. 14, the punching state of the master 64 is such that each punching h is punched largely only in the sub-scanning direction F, and the sub-scanning is not performed in the sub-scanning direction F and the main scanning direction S. A perforation h having an optimal size adapted to a resolution of 300 DPI in the direction F is obtained. Further, by applying two continuous energization pulses corresponding to the energization pulse widths tp2 and tp4, the temperature at which the heating element peak temperature of the thermal head 59 is required for drilling of the master 64, that is, the threshold temperature of the master 64 Since the size of the perforation h in the sub-scanning direction F of the master 64 can be set to a desired size without increasing it more unnecessarily, this reduces the thermal stress applied to the heating element of the thermal head 59, And it can be made small. Therefore, according to this embodiment, there is an advantage that the life of the thermal head 59 can be improved. Reference tp3 indicates the energization off time between the energization pulse widths tp2 and tp4. Note that the size of the perforation h in the main scanning direction S has no influence as shown in the figure, and is ignored in the perforated state in FIG. 14 in order to clarify the feature.

  By the way, in the above embodiment, when the resolution in the sub-scanning direction F is set to 300 DPI, two energization pulses corresponding to energization pulse widths tp2 and tp4 continuous to the heating element of the thermal head 59 are applied to one image signal. Although the method of forming the perforation h having the optimum size in the sub-scanning direction F of the master 64 by applying is described, the life of the heating element of the thermal head 59 due to thermal stress is at a level where there is no problem in actual use. For example, as shown in FIG. 15, the energization pulse corresponding to one energization pulse width tp5 is applied to one image signal to the heating element of the thermal head 59, as shown in FIG. You may adjust. Here, the energization pulse width tp5 is set longer (larger) than the energization pulse width tp1 applied to the heating element of the thermal head 59 when the resolution in the sub-scanning direction F is set to 400 DPI.

  In FIG. 15A, when the energization pulse width (energization time) applied to the heating element of the thermal head 59 is tp1, the heating temperature of the heating element of the thermal head 59 is partially shown in FIG. The temperature rise / fall curve is as shown by the broken line. Accordingly, the master 64 at this time is formed with a perforation h ′ having a size as shown by a broken line in FIG. In this case, the size of the perforation h ′ formed in the master 64 is optimal when the resolution in the sub-scanning direction F is set to 400 DPI, but when the resolution in the sub-scanning direction F is set to 300 DPI. too small. Therefore, one energization pulse corresponding to the energization pulse width tp5 set longer than the energization pulse width tp1 may be applied to the heating element of the thermal head 59. As a result, the peak temperature of the heating element of the thermal head 59 becomes higher than the peak temperature indicated by the broken line in FIG. 15B, as indicated by the solid line in FIG. At the same time, as shown in FIGS. 16 (a) and 16 (b), the temperature distribution at the point ca of the central portion of the heating element 1A of the thermal head 59 in the sub-scanning direction F (indicated by the alternate long and short dash line in FIG. 16 (a)). As shown by the solid line in FIG. 5B, when a current pulse having a length tp1 in the sub-scanning direction F that is equal to or higher than the threshold temperature D is applied in the master 64 (in FIG. Longer than that shown by the broken line). Thereby, when the energization pulse applied to the heating element of the thermal head 59 has the energization pulse width tp5, the master 64 is formed with a perforation h having a size as shown in FIG. A perforation h having an optimum size adapted to the case where the resolution in the sub-scanning direction F is set to 300 DPI can be obtained. When the energization pulse applied to the heating element of the thermal head 59 has the energization pulse width tp5, the master 64 applies to the master 64 more than when the energization pulse applied to the heating element of the thermal head 59 has the energization pulse width tp1. Although the size of the formed perforation h in the main scanning direction S is increased, the influence of the spread of the size is less than the size of the perforation h in the sub-scanning direction F, and therefore there is no problem in practical use. Therefore, according to this embodiment, when the resolution in the sub-scanning direction F is set to 300 DPI as in the above embodiment, two energization pulse widths continuous to the heating element of the thermal head 59 for one image signal. By applying energization pulses corresponding to tp2 and tp4, there is an advantage that the control method can be simplified as compared with the method of forming the perforation h having the optimum size in the sub-scanning direction F of the master 64.

  Thus, taking into account the above-described matters, Table 1 shows an example of setting the energization pulse width based on the setting of the resolution in the sub-scanning direction.

  As the plate making conditions, the thermal head 59 has a resolution of 300 DPI in the main scanning direction, and the resolution in the sub-scanning direction can be selected from 300 DPI and 400 DPI. The size of the heating element of the thermal head 59 is 50 μm in the main scanning direction and 40 μm in the sub-scanning direction, and its line cycle Th is 3 msec / line. The plate making environment was performed at room temperature at 20 ° C. In Table 1, tp1 to tp4 are the same as those shown in FIGS. 11 and 13, and tp5 is the same energization pulse width (time: μsec) as shown in FIGS.

  Thus, by providing the energization pulse width as shown in Table 1, the optimum size adapted to the resolution in the sub-scanning direction is obtained without connecting and punching in the main scanning direction S and the sub-scanning direction F under the same use conditions. Perforations were obtained, and the optimum printed image quality was obtained.

  The size in the sub-scanning direction of the heating element of the heat generating portion of the thermal head 59 is preferably set to a size in the range of 80% or less of the length of the feed pitch corresponding to the highest resolution that can be set by the sub-scanning direction resolution setting means. desirable. In the case of this embodiment, the maximum resolution in the sub-scanning direction that can be set with the density setting key 112 is 400 DPI, and the feed pitch is 63.5 μm / line, so the dimension in the sub-scanning direction of the heating element is 51 μm or less. Is more desirable. Thereby, even when the resolution in the sub-scanning direction is increased, it is possible to more reliably perform the perforation independently without being connected in the sub-scanning direction.

  Further, it is desirable that the dimension in the sub-scanning direction of the heating element of the heating part of the thermal head 59 is a size in the range of 40% or more of the length of the feed pitch corresponding to the highest resolution that can be set with the density setting key 112. . In the case of this embodiment, the maximum resolution in the sub-scanning direction that can be set with the density setting key 112 is 400 DPI, and the feed pitch is 63.5 μm / line. Therefore, the dimension of the heating element in the sub-scanning direction is 25 μm or more. Is desirable. As described above, by making the size in a range of 40% or more of the length of the feed pitch, it is possible to surely perforate. This is because if the heating element is too small, the life of the heating element is reduced by repeated heating.

  As described in the above embodiment, the dimension in the sub-scanning direction of the heating element of the heat generating part of the thermal head 59 has a certain value corresponding to the feed pitch corresponding to the resolution in the sub-scanning direction indicating the resolution of the stencil printing apparatus. Have. For example, as shown in FIG. 17A, in the case of a stencil printing apparatus having a resolution of 300 DPI (dots / inch) in both the main scanning direction S and the sub-scanning direction F, the heating element of the heat generating part of the thermal head used therefor The size is 50 μm in the main scanning direction and 60 μm in the sub scanning direction. The master 64 is punched by the thermal head as shown in FIG. Further, it is considered that the print image quality is improved by increasing the resolution in the sub-scanning direction F. For example, as shown in FIG. 17B, a resolution of 300 DPI in the main scanning direction S and a sub-scanning direction F When the resolution is 400 DPI, the heating element size of the heating part of the thermal head is 50 μm in the main scanning direction and 40 μm in the sub-scanning direction. The perforated state of the master 64 is as shown in FIG.

  By the way, the plate-making time required for plate-making from the same document differs depending on the resolution in the sub-scanning direction when the line cycle of one line is the same, and becomes longer as the resolution is higher. That is, as described above, when printing is performed by a stencil printing apparatus having a resolution of 300 DPI in both the main scanning direction and the sub-scanning direction, the printing image quality is lowered, but the plate making time is shortened. Conversely, when printing is performed with a stencil printing apparatus having a resolution of 300 DPI in the main scanning direction and 400 DPI in the sub-scanning direction, the printing image quality is improved although the plate making time is increased.

  Further, in the case of considering changing the resolution in the sub-scanning direction with the stencil printing apparatus using the same thermal head, for example, as shown in FIG. 18A, the main scanning direction S and the sub-scanning direction F When both thermal heads having a resolution of 300 DPI are used, an optimum perforation diameter that gives good print image quality is obtained when the resolution in the sub-scanning direction F is 300 DPI (see FIG. 18B). When the resolution in the scanning direction F is changed to 400 DPI, each perforation becomes a connected perforation connected in the sub-scanning direction F (see FIG. 18C), and the amount of ink transferred to the printing paper increases. There arises a problem of so-called back-off in which the ink on the surface of the printed paper that has been ejected is transferred to the back surface of the printed paper that has been ejected next and the back surface of the printed paper is soiled.

  On the other hand, as shown in FIG. 19A, when a thermal head having resolutions for the main scanning direction of 300 DPI and the sub scanning direction of 400 DPI is used, good print image quality is obtained when the resolution of the sub scanning direction F is 400 DPI. However, when the resolution in the sub-scanning direction F is changed to 300 DPI, each perforation is too far away in the sub-scanning direction F and the ink bleeds on the printing paper. May not follow and white streaks may occur (see FIG. 19B).

In addition, according to the form shown in FIG.11 and FIG.12, there exists an advantage which can be selectively used as follows. That is, in the case of setting the resolution of 300 DPI in the sub-scanning direction where the plate making time is short, even if the white streaks described in FIG. 19B occur, the plate making time is short without worrying about it. In the case where it is good, or when it is intended to reduce the amount of ink transferred to the printing paper, that is, the amount of ink consumption, etc., two continuous energization pulse widths tp2, as shown in FIG. 13 and FIG. It is not necessary to set tp4 or to set a single energization pulse width tp5 longer than the energization pulse width tp1 as in the embodiments shown in FIGS. That is,
In this embodiment, as shown in FIG. 13 and FIG. 14, the embodiment is not limited to a mode in which two continuous energization pulse widths are set, and the punching energy adjusting means applies at least the punching energy to one image signal. You may adjust so that it may apply twice or more, ie, it may apply continuously several times.

  The stencil printing apparatus can use a heat-sensitive stencil master consisting essentially of only a thermoplastic resin film. For example, a stencil printing machine having a thickness of 1.6 μm is used under the same conditions as in the above embodiment. When perforation is performed, independent perforation is performed without connecting each perforation in the main scanning direction and the sub-scanning direction as in the above embodiment, and a desired print image corresponding to the resolution in the sub-scanning direction can be obtained. It was possible to obtain a good print image free from soiling of the printing paper due to set-off and so-called fiber texture.

  For example, the resolution in the sub-scanning direction may be changed continuously from 300 DPI to 400 DPI in addition to the resolution gradually changing from 300 DPI to 400 DPI as in the present embodiment. As means for changing to the feed pitch corresponding to the resolution in the sub-scanning direction, there is a device described in Japanese Utility Model Laid-Open No. 59-161765, that is, page 4, line 9 to page 5, page 10 of the same specification. A mechanism similar to that described in the row may be used. Needless to say, the feeding operation for transporting the master 64 in the sub-scanning direction is not limited to the intermittent movement of the master 64 at a predetermined feeding pitch as in the above embodiment.

1 is a configuration diagram showing a stencil printing apparatus to which an embodiment of the present invention is applied. FIG. 4 is an enlarged view showing a configuration in the vicinity of a refeed unit. It is the schematic explaining the contacting / separating mechanism of a printing pressure member. It is the schematic explaining the division | segmentation prepress master. It is the schematic explaining a pre-printed master. It is a block diagram which shows one structure of the control part of a stencil printing apparatus. It is a block diagram which shows one structure of the control part concerning plate making. It is the elements on larger scale which show one form of an operation panel. (A) is a case where the resolution in the main scanning direction and the sub-scanning direction is both set to 300 DPI, and (b) is a heat sensitivity when the resolution in the main scanning direction is set to 300 DPI and the resolution in the sub-scanning direction is set to 400 DPI. The perforation state of the stencil master is shown respectively. It is a flowchart which shows one form of the switching process of platemaking density. (A) shows the setting state of the energization pulse width applied to the same heating element when the resolution in the sub-scanning direction is set to 400 DPI, and (b) shows the heating element of the thermal head in the setting state of the same energization pulse width. The exothermic temperature transition state of is shown. 11 shows the punched state of the heat-sensitive stencil master in the states of FIGS. (A) shows the setting state of energization pulse width applied to the same heating element when the resolution in the sub-scanning direction is set to 300 DPI, and (b) shows the heating element of the thermal head in the setting state of the same energization pulse width. The exothermic temperature transition state of is shown. 13 shows the punching state of the heat-sensitive stencil master in the states of FIGS. 13 (a) and (b). (A) shows the setting state of energization pulse width applied to the same heating element when the resolution in the sub-scanning direction is set to 300 DPI, and (b) shows the heating element of the thermal head in the setting state of the same energization pulse width. The exothermic temperature transition state of is shown. (A) is a top view which shows the arrangement | sequence state of the heat generating body of a thermal head, (b) shows the difference in the temperature distribution state of a heat generating body based on the difference in the setting of an energization pulse width, (c) is an energization pulse width. The difference in the drilling state of the heat-sensitive stencil master based on the difference in the setting is shown. (A) is a case where the resolution in the main scanning direction and the sub-scanning direction is both set to 300 DPI, and (b) is a heat sensitivity when the resolution in the main scanning direction is set to 300 DPI and the resolution in the sub-scanning direction is set to 400 DPI. The perforation state of the stencil master is shown respectively. (A) shows the heat generating element dimensions of the thermal head whose resolution in the main scanning direction and the sub-scanning direction is 300 DPI, (b) shows the case where the resolution in the sub-scanning direction is set to 300 DPI, and (c) shows the sub-scanning direction. The perforation state of the heat-sensitive stencil master when the resolution is set to 400 DPI is shown. (A) shows the heating element dimensions of the thermal head with a resolution in the main scanning direction of 300 DPI and a resolution in the sub-scanning direction of 400 DPI, and (b) shows a case where the resolution in the sub-scanning direction is set to 300 DPI ( c) shows the punching state of the heat-sensitive stencil master when the resolution in the sub-scanning direction is set to 400 DPI.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1A Many heat generating parts 12 Printing drum 58 Punching means 59 Platen roller 64 Thermosensitive stencil master 91A First original 91B Second original 112 Sub-scanning direction resolution setting means 160 Punching energy adjusting means 224 Master transport means P Printing paper S Main scanning direction F Sub-scanning direction tp1 to tp2, tp4 to tp5 Energization pulse width (energization time)

Claims (4)

Sub-scanning orthogonal to the main scanning direction in a state where a heat-sensitive stencil master having at least a thermoplastic resin film is pressed by a platen roller against punching means having a large number of heat generating portions arranged in the main scanning direction. While moving the thermosensitive stencil master in the direction by the master conveying means, the heat generating portion is heated according to the image signal to selectively melt and perforate the thermoplastic resin film to form a perforation pattern according to the image signal. The heat-sensitive stencil master is wound around the outer peripheral surface of the printing drum, ink is supplied from the inside of the printing drum, and an ink image corresponding to the image signal is formed by ink that has oozed through the perforation pattern. In a stencil printing machine capable of duplex printing that prints on printing paper,
Stencil printing comprising sub-scanning direction resolution setting means for setting the resolution in the sub-scanning direction for each of the first document corresponding to the front image and the second document corresponding to the back image during duplex printing apparatus. In the stencil printing apparatus according to claim 1,
Drilling energy adjusting means for adjusting the drilling energy supplied to the heat generating portion of the punching means to a predetermined energy;
The dimension in the sub-scanning direction of the heat generating portion is made equal to or less than the length of the feed pitch of the heat-sensitive stencil master by the master conveying unit corresponding to the highest resolution that can be set by the sub-scanning direction resolution setting unit. A stencil printing device. In the stencil printing apparatus according to claim 2,
The stencil printing apparatus, wherein the piercing energy adjusting means adjusts the piercing energy so as to be continuously applied a plurality of times to one image signal. In the stencil printing apparatus according to claim 2,
The perforation energy is set to be adjusted by changing the energization pulse width, and the resolution in the sub-scanning direction is relative to the resolution that can be set by the sub-scanning direction resolution setting means. When the energizing pulse width is longer than the energizing pulse width set corresponding to a relatively high resolution for one image signal when the perforation energy adjusting means is set to a low resolution. The stencil printing apparatus is characterized in that the perforating energy is adjusted so as to be applied once.

Images