JP2005297196A - Stencil printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stencil printer which prevents the waste of ink by surely suppressing a deterioration in the ink, and which enables the recovered ink to be automatically used for the next printing or later. <P>SOLUTION: This stencil printer is equipped with: a rotatable drum 26 which has the outer peripheral wall 52 formed of an ink-impermeable member, and which makes stencil base paper attached to a surface of the outer peripheral wall 53; an ink supply means 54 whose ink supply port 55 is provided on the outer peripheral wall 53 of the drum 26, and which supplies ink, guided from an ink tank 57, from the ink supply port 55 to the surface of the outer peripheral wall 53; an ink recovery means 73 whose ink recovery port 72 is provided on the outer peripheral wall 53 of the drum 26, and which recovers the surplus ink on the surface of the outer peripheral wall 53 from the ink recovery port 72; and a press roll 35 for pressing fed printing paper against the outer peripheral wall 53. The ink recovery means 73 returns the surplus ink, recovered from the ink recovery port 72, to the ink tank 57. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a stencil printing apparatus for transferring a printing medium while pressing the printing medium to a drum on which the stencil sheet is mounted, and transferring the ink that oozes out from the perforation of the stencil sheet to the printing medium.

  As a printing method of a conventional stencil printing apparatus, there are an inner press method (for example, see Patent Document 1) and an outer press method (for example, see Patent Document 2).

  The inner press method will be briefly described. As shown in FIG. 9, the drum 100 has a drum 100 and a paper cylinder 101, and the drum 100 and the paper cylinder 101 are rotatable in a state where a part of their outer peripheral surfaces are substantially close to each other. Is provided. A base paper clamp portion 100a for clamping the tip of the stencil base paper 104 is provided on the outer peripheral surface of the drum 100, and the outer peripheral wall other than the base paper clamp portion 100a is flexible and has an ink-permeable screen 102. Is formed.

  An ink supply mechanism 105 is provided inside the drum 100. As shown in FIG. 10, the ink supply mechanism 105 includes an intermediate push roll 106 that is an ink supply roll, and the intermediate push roll 106 is rotatably provided on a roll support member 107. The intermediate pressing roll 106 has a pressing position where the roll support member 107 is urged in the direction of arrow a in FIG. 10 to be pressed against the inner peripheral surface of the screen 102, and the roll support member 107 is rotated in the direction of arrow b in FIG. 10. Thus, it is configured to be able to change between a standby position separated from the inner peripheral surface of the screen 102. The intermediate pressing roll 106 is set to a pressing position when the printing paper 111 passes, and is set to a standby position otherwise. Further, the intermediate pressing roll 106 has a function of applying a printing pressure from the inner peripheral side of the screen 102.

  The roll support member 107 is supported so as to be rotatable about a support shaft 108, and the roll support member 107 is provided with a doctor roll 109 and a drive rod 110, respectively. The doctor roll 109 has a cylindrical shape, and is fixed to the roll support member 107 at a position close to the intermediate push roll 106. The drive rod 110 is rotatably supported by the roll support member 107, and is disposed in an upper space constituted by the outer peripheral surfaces of the intermediate push roll 106 and the doctor roll 109 on the sides close to each other. Ink 103 is supplied to the upper space from an ink supply unit (not shown).

  Next, the outline operation of printing will be described in order. A stencil sheet 104 on which a perforated image is formed is mounted on the outer peripheral surface of the screen 102. In the printing mode, the drum 100 and the paper cylinder 101 are rotated synchronously in the direction indicated by the arrow in FIG. 9, and the printing paper 111 is fed between the drum 100 and the paper cylinder 101.

  When the printing paper 111 is fed, the intermediate pressing roll 106 presses the screen 102, and the intermediate pressing roll 106 rotates following the drum 100 in this pressed state. The ink 103 that has passed through the gap with the doctor roll 109 adheres to the outer peripheral surface of the intermediate pressing roll 106, and the attached ink 103 is sequentially supplied to the inner surface of the screen 102 by the rotation of the intermediate pressing roll 106.

  When the intermediate pressing roll 106 presses the screen 102, the pressing force causes the screen 102 to bulge to the outer peripheral side, and the screen 102 is brought into pressure contact with the paper cylinder 101. Then, the printing paper 111 conveyed between the drum 100 and the paper cylinder 101 is conveyed between the intermediate pressing roll 106 and the paper cylinder 101 while being pressed against the screen 102 and the stencil sheet 104. The ink 103 on the screen 102 side is transferred to the printing paper 111 side from the perforation of the stencil sheet 104 by this pressure contact force, and an ink image is printed on the printing paper 111.

  The outer press method will be briefly described. As shown in FIG. 11, the drum 120 has a drum 120, and a base paper clamp portion 120a for clamping the tip of the stencil base paper 104 is provided on the outer peripheral surface of the drum 120. The outer peripheral wall 120b other than the base paper clamp portion 120a is formed of a porous ink-permeable member (ink-permeable member).

  An ink supply mechanism 125 is provided inside the drum 120. The ink supply mechanism 125 includes a squeegee roll 126 that is rotatably supported and a doctor roll 127 that is disposed in the vicinity of the squeegee roll 126. The ink supply mechanism 125 is disposed in an outer peripheral space surrounded by the squeegee roll 126 and the doctor roll 127. Ink 128 is stored. As the ink 128 adhering to the outer periphery of the rotating squeegee roll 126 passes through the gap with the doctor roll 127, only the ink 128 having a predetermined thickness is attached to the squeegee roll 126. It is supplied to the inner surface of the outer peripheral wall 120b.

  Further, a press roll 130 is provided at a position facing the squeegee roll 126 and outside the drum 120. The press roll 130 presses the outer peripheral wall 120b of the drum 120 and the outer peripheral wall 120b of the drum 120. It is configured to be able to change between a standby position that is separated from the standby position. The squeegee roll 126 is fixed to a support portion that rotatably supports the outer peripheral wall 120b of the drum 120, and the outer periphery of the squeegee roll 126 is not pressed by the press roll 130. The surface and the inner peripheral surface of the outer peripheral wall 120b of the drum 120 are in a slightly spaced state. When the outer peripheral wall 120b of the drum 120 is pressed by the press roll 130, the outer peripheral wall 120b of the drum 120 is bent, so that the outer peripheral surface of the squeegee roll 126 and the inner peripheral surface of the outer peripheral wall 120b of the drum 120 come into contact with each other. To do.

  Next, the outline operation of printing will be described in order. The stencil sheet 104 on which the perforated image is formed is mounted on the outer peripheral surface of the outer peripheral wall 120b of the drum. In the printing mode, the outer peripheral wall 120 b of the drum 120 is rotated in the direction indicated by the arrow in FIG. 11, and the printing paper 111 is fed between the drum 120 and the press roll 130.

  When the printing paper 111 is fed, the press roll 130 presses the outer peripheral wall 120b of the drum 120, and the outer peripheral wall 120b is displaced to the inner peripheral side. Due to this displacement, the outer peripheral wall 120b is pressed against the squeegee roll 126, and the squeegee roll 126 rotates following the drum 120. The ink 128 that has passed through the gap with the doctor roll 127 adheres to the outer peripheral surface of the squeegee roll 126, and the attached ink 128 is sequentially supplied to the inner surface of the outer peripheral wall 120b by the rotation of the squeegee roll 126.

When the press roll 130 presses the outer peripheral wall 120 b of the drum 120, the printing paper 111 conveyed between the drum 120 and the press roll 130 is pressed against the stencil sheet 104 between the squeegee roll 126 and the press roll 130. It is conveyed while. By this pressure contact force, the ink 128 on the outer peripheral wall 120 b side is transferred to the printing paper 111 side from the perforation of the stencil sheet 104, and an ink image is printed on the printing paper 111.
JP-A-7-132675 JP 2001-246828 A

  However, in the conventional inner press type and outer press type stencil printing apparatuses, ink pools are respectively provided in the outer peripheral space of the intermediate pressing roll 106 and the doctor roll 109 and in the outer peripheral space of the squeegee roll 126 and the doctor roll 127. Then, the ink 103 and 128 in the ink reservoir is supplied to the screen 102 and the outer peripheral wall 120b of the drums 100 and 120 during printing. Here, the inks 103 and 128 attached to the ink reservoirs 103 and 128, the drums 100 and 120, etc. are held in that position even after the printing is completed, and are used for the next and subsequent printing. Therefore, when printing is not performed for a long time after the next time, the inks 103 and 128 accumulated in the ink reservoir, the inks 103 and 128 attached to the drums 100 and 120, etc. are left in contact with the atmosphere for a long time. As a result, the inks 103 and 128 are altered. When printing is performed with the altered inks 103 and 128, a desired image quality cannot be obtained. Therefore, it is necessary to discard the altered ink by performing discard printing or the like, and there is a problem that the ink is wasted.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a stencil printing apparatus that reliably suppresses ink deterioration, eliminates waste of ink, and can automatically use the collected ink for subsequent printing. .

  The invention according to claim 1, which achieves the above object, comprises a drum having an outer peripheral wall that is rotatable and formed of an ink-impermeable member, and a stencil sheet is mounted on the surface of the outer peripheral wall, and the drum. And an ink supply unit for supplying ink guided from an ink tank to the surface of the outer peripheral wall from the ink supply unit, and an ink recovery unit on the outer peripheral wall of the drum. A stencil printing apparatus comprising: an ink collecting means for collecting excess ink on the surface of the outer peripheral wall from the ink collecting portion; and a press roll for pressing a fed printing medium against the outer peripheral wall. The collecting means is configured to return the excess ink collected from the ink collecting unit to the ink tank.

  In this stencil printing apparatus, excess ink that has not been used for printing on the outer peripheral wall of the drum is recovered by the ink recovery means, and the recovered excess ink is returned to the ink tank of the ink supply means.

  A second aspect of the invention is the stencil printing apparatus according to the first aspect, wherein a filter for trapping impurities in the ink is interposed in a path for returning the ink from the ink recovery section to the ink tank. .

  In this stencil printing apparatus, ink recovered from the outer peripheral wall of the drum passes through a filter, and impurities such as paper dust in the ink are trapped by the filter.

  A third aspect of the present invention is the stencil printing apparatus according to the first aspect, wherein the ink supply means and the ink recovery means are always driven in a printing mode.

  In this stencil printing apparatus, ink is continuously supplied to the outer peripheral wall from the ink supply port in the printing mode, and the ink that has entered the ink recovery port from the outer peripheral wall is always recovered. Further, an appropriate amount of ink is always held on the outer peripheral wall.

  According to a fourth aspect of the present invention, in the stencil printing apparatus according to the third aspect, at the end of the printing mode, the drive of the ink collecting means is stopped with a slight delay from the stop of the drive of the ink supply means. Features.

  In this stencil printing apparatus, it is possible to prevent excess ink from remaining in the substantially sealed space between the outer peripheral wall of the drum and the stencil sheet after the end of the printing mode.

  According to the first aspect of the present invention, excess ink that has not been used for printing on the outer peripheral wall of the drum is recovered by the ink recovery means, and the recovered excess ink is returned to the ink tank of the ink supply means. Therefore, it is possible to reliably suppress the situation in which the excess ink is deteriorated on the outer peripheral wall of the drum to eliminate the waste of the ink, and to automatically use the collected ink for the subsequent printing.

  According to the invention of claim 2, the ink collected from the outer peripheral wall of the drum passes through the filter, and impurities such as paper dust in the ink are trapped by the filter. Therefore, the quality of the recovered ink can be improved.

  According to the invention of claim 3, since the ink is continuously supplied from the ink supply port to the outer peripheral wall in the printing mode and the ink that has entered the ink recovery port from the outer peripheral wall is always recovered, the ink is supplied to the outer peripheral wall. It can prevent staying. In addition, since an appropriate amount of ink can be constantly held on the outer peripheral wall, a printed matter having a desired ink density can be obtained even during a large amount of continuous printing.

  According to the fourth aspect of the present invention, it is possible to prevent excess ink from remaining in the substantially sealed space between the outer peripheral wall of the drum and the stencil sheet after the end of the printing mode. Accordingly, it is possible to further suppress the situation where the excess ink is deteriorated on the outer peripheral wall of the drum, and it is possible to more effectively eliminate the waste of ink.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  1 to 5 show an embodiment of the present invention, FIG. 1 is a schematic configuration diagram of a stencil printing apparatus, FIG. 2 is a perspective view of a drum, and FIG. 3 is a sectional view taken along line AA in FIG. 4 is a cross-sectional view taken along line BB in FIG. 2, and FIG. 5 is a partial cross-sectional view illustrating the ink diffusion mechanism.

  As shown in FIG. 1, the stencil printing apparatus mainly includes a document reading unit 1, a plate making unit 2, a printing unit 3, a paper feeding unit 4, a paper discharging unit 5, and a plate discharging unit 6. .

  The document reading unit 1 includes a document setting table 10 on which a document to be printed is placed, reflection-type document sensors 11 and 12 that detect the presence of documents on the document setting table 10, and documents on the document setting table 10. The document transport rolls 13 and 14 to be transported, the stepping motor 15 that rotationally drives the document transport rolls 13 and 14, and the image data of the document transported by the document transport rolls 13 and 14 are optically read and converted into electrical signals. A contact type image sensor 16 for conversion and a document discharge tray 17 for placing a document discharged from the document setting table 10 are provided. Then, the document placed on the document setting table 10 is transported by the document transport rollers 13 and 14, and the image sensor 16 reads the image data of the transported document.

  The plate making unit 2 includes a base paper storage unit 19 that stores the rolled long stencil base paper 18, a thermal head 20 that is disposed downstream of the base paper storage unit 19, and a position opposite to the thermal head 20. A platen roll 21, a pair of base paper feed rolls 22, 22 arranged downstream of the transport of the platen roll 21 and the thermal head 20, a light pulse motor 23 that rotationally drives the platen roll 21 and the base paper feed roll 22, And a base paper cutter 24 disposed downstream of the pair of base paper feed rolls 22 and 22.

  Then, the long stencil sheet 18 is transported by the rotation of the platen roll 21 and the base paper feed roll 22, and each point-like heating element of the thermal head 20 selectively generates heat based on the image data read by the image sensor 16. Thus, the stencil sheet 18 is made by heat-sensitive perforation, and the stencil sheet 18 thus made is cut by a stencil sheet cutter 24 to produce a stencil sheet 18 having a predetermined length.

  The printing unit 3 includes a drum 26 that rotates in the direction of arrow A in FIG. 1 by the driving force of the main motor 25, a base paper clamp unit 27 that is provided on the outer peripheral surface of the drum 26 and clamps the leading end of the stencil base paper 18, and a drum Ink supply means 54 for supplying ink to the surface of the drum 26 and ink recovery means 73 for collecting excess ink on the surface of the drum 26 are provided.

  The printing unit 3 includes a base paper confirmation sensor 28 that detects whether or not the stencil paper 18 is wound around the outer peripheral surface of the drum 26, a reference position detection sensor 30 that detects the reference position of the drum 26, and a main motor. And a rotary encoder 31 for detecting 25 rotations. The rotational position of the drum 26 can be detected by detecting the output pulse of the rotary encoder 31 based on the detection output of the reference position detection sensor 30.

  Further, the printing unit 3 includes a press roll 35 disposed at a position below the drum 26. The press roll 35 is pressed against the outer peripheral surface of the drum 26 by the driving force of the solenoid device 36. It is configured to be able to change between a standby position separated from the outer peripheral surface. The press roll 35 is always positioned at the pressing position during the printing mode period (including trial printing), and is positioned at the standby position during the period other than the printing mode.

  Then, the leading end of the stencil sheet 18 conveyed from the plate making unit 2 is clamped by the stencil sheet clamp unit 27, and the drum 26 is rotated in this clamped state so that the stencil sheet 18 is wound around the outer peripheral surface of the drum 26. The printing paper (printing medium) 37 fed from the paper feeding unit 4 in synchronism with the rotation of the paper is pressed against the stencil paper 18 wound around the drum 26 by the press roll 35, whereby the stencil paper 18 is applied to the printing paper 37. The ink 56 is transferred from the perforations, and an image is printed.

  The paper feed unit 4 includes a paper feed tray 38 on which the print paper 37 is stacked, primary paper feed rolls 39 and 40 that transport only the uppermost print paper 37 from the paper feed base 38, and the primary paper feed. A pair of secondary paper feed rolls 41 and 41 for conveying the printing paper 37 conveyed by the rolls 39 and 40 between the drum 26 and the press roll 35 in synchronization with the rotation of the drum 26, and the pair of secondary paper feed rolls A paper feed sensor 42 that detects whether or not the printing paper 37 has been conveyed between 41 and 41. The primary feed rolls 39 and 40 are configured to selectively transmit the rotation of the main motor 25 via the feed clutch 43.

  The paper discharge unit 5 includes a paper separation claw 44 that separates the printed printing paper 37 from the drum 26, a conveyance path 45 through which the printing paper 37 separated from the drum 26 by the paper separation claw 44 is conveyed, And a paper discharge tray 46 on which the printing paper 37 discharged from the conveyance path 45 is placed.

  The plate discharging unit 6 guides the leading end of the stencil sheet 18 unclamped from the outer peripheral surface of the drum 26 and transports the guided used stencil sheet 18 while being peeled off from the drum 26, and this plate discharging transport. A stencil box 48 for storing the stencil sheet 18 conveyed by the means 47 and a stencil compression member 49 for pushing the stencil sheet 18 conveyed into the stencil box 48 by the stencil conveying means 47 into the stencil box 48 are provided. Have.

  Next, the configuration of the drum 26, the base paper clamp unit 27, the ink supply unit 54, and the ink collection unit 73 will be described.

  As shown in FIGS. 2 to 4, the drum 26 includes a pair of support shafts 50 fixed to the apparatus main body H (shown in FIG. 1) and a pair of shafts 50 rotatably supported by the support shafts 50 through respective bearings 51. Side discs 52 and 52, and a cylindrical outer peripheral wall 53 fixed between the pair of side discs 52 and 52. The outer peripheral wall 53 is integrally driven with the pair of side disks 52 and 52 by the rotational force of the main motor 25. The outer peripheral wall 53 is formed of an ink impermeable member that has rigidity and does not allow the ink 56 to pass therethrough. Note that, depending on the type of the ink impermeable member, for the purpose of forming the outer peripheral surface of the outer peripheral wall 53 into a cylindrical surface without unevenness, etc., fluororesin processing such as Teflon (registered trademark) processing, nickel plating, nickel chrome Various known surface treatments such as plating, hot dip galvanizing, and anodizing may be performed.

  The base paper clamp portion 27 is provided by using a clamp recess 53 a formed along the axial direction of the support shaft 50 of the outer peripheral wall 53. One end of the base paper clamp portion 27 is rotatably supported by the outer peripheral wall 53 and protrudes from the outer peripheral wall 53 in the clamp release state indicated by the phantom line in FIG. 4, but in the clamped state indicated by the solid line in FIG. 53 so as not to protrude from 53. Therefore, the stencil paper clamping unit 27 can clamp the stencil paper 18 without protruding onto the outer peripheral wall 53.

  The outer peripheral wall 53 is rotated in the direction of arrow A in FIGS. 2 and 4, and the position where the outer peripheral wall 53 is slightly rotated from the base paper clamp portion 27 is the printing start point. Therefore, the rotation direction A becomes the printing direction M, and the area below the printing start point is the printing area. In the first embodiment, the maximum print area is set to an area capable of A3 size printing. An ink supply port 55 of the ink supply means 54 is provided upstream of the maximum print area of the outer peripheral wall 53 in the printing direction M.

  As shown in FIGS. 2 to 4, the ink supply means 54 includes an ink tank 57 in which ink is stored, an ink pump 58 that sucks ink in the ink tank 57, and ink sucked by the ink pump 58. A first pipe 59 for supplying the liquid, a support shaft 50 in which the other end of the first pipe 59 is connected, an ink passage 60 is formed therein, and a hole 61 is formed at a position opposed to 180 degrees; A rotary joint 63 that is rotatably supported on the outer peripheral side of the shaft 50 and has a communication hole 62 that can communicate with the hole 61, one end connected to the rotary joint 63, and the other end led to the outer peripheral wall 53. The second pipe 64 and the other end side of the second pipe 64 are connected and an ink supply port 55 which is an ink supply part opened on the surface of the outer peripheral wall 53 is configured.

  The ink supply port 55 is formed using an ink supply recess formed continuously along the printing orthogonal direction N of the outer peripheral wall 53 and an ink distribution member 68 disposed inside the recess.

  As shown in FIGS. 2 to 4, the ink collection unit 73 includes an ink collection port 72 that is an ink collection unit that is opened downstream of the maximum printing area of the outer peripheral wall 53, and one end of the ink collection port 72. The connected third pipe 74 is connected to the other end of the third pipe 74 and a communication hole 75 is formed. The rotary joint 63 is rotatably supported and the communication hole 75 can be connected. A support shaft 50 having an inner hole 76a and an ink passage 76b formed therein, a fourth pipe 77 having one end connected to the support shaft 50, and a middle portion of the fourth pipe 77. An ink pump (for example, a trochoid pump) 78 that sucks the ink 56 is provided, and the other end of the fourth pipe 77 is connected to the ink tank 57 of the ink supply means 54.

  The ink recovery port 72 is formed using an ink recovery recess formed continuously along the printing orthogonal direction N of the outer peripheral wall 53 and a pipe fixing member 82 disposed inside the recess.

  The rotary joint 63 is also used as the ink supply means 54. Further, since the support shaft 50 is also used in the ink passage of the ink supply means 54, it has a double pipe structure.

  Next, the operation of the stencil printing apparatus having the above configuration will be briefly described.

  First, when the plate making mode is selected, the plate making unit 2 transports the stencil sheet 18 by the rotation of the platen roll 21 and the base paper feed roll 22, and a number of thermal heads 20 are based on the image data read by the document reading unit 1. When the heating element selectively generates heat, the stencil sheet 18 is thermally perforated to make a plate, and a predetermined portion of the stencil sheet 18 is cut with a stencil cutter 24 to make a stencil sheet 18 having a desired size.

  In the printing unit 3, the tip of the stencil sheet 18 made by the plate making unit 2 is clamped by the stencil sheet clamping unit 27 of the drum 26, and in this clamped state, the drum 26 is rotated to place the stencil sheet 18 on the outer peripheral surface of the drum 26. Wrap and plate.

  Next, when the printing mode is selected, the drum 26 is rotated in the printing unit 3 and the ink supply unit 54 and the ink collection unit 73 are started to be driven. Then, the ink 56 is supplied to the outer peripheral wall 53 from the ink supply port 55, and the supplied ink 56 is held between the outer peripheral wall 53 and the stencil sheet 18, and the press roll 35 is displaced from the standby position to the pressing position. Is done.

  In synchronization with the rotation of the drum 26, the paper feeding unit 4 feeds the printing paper 37 between the drum 26 and the press roll 35. The fed printing paper 37 is pressed against the outer peripheral wall 53 of the drum 26 by the press roll 35 and is conveyed by the rotation of the outer peripheral wall 53 of the drum 26. That is, the printing paper 37 is conveyed while being in close contact with the stencil sheet 18.

  In parallel with the conveyance of the printing paper 37, as shown in FIG. 5, the ink 56 held between the outer peripheral wall 53 of the drum 26 and the stencil sheet 18 is squeezed by the pressing force of the press roll 35. While being diffused downstream in the printing direction M, the diffused ink 56 oozes out from the perforation of the stencil sheet 18 and is transferred to the printing paper 37 side. Thereby, an ink image is printed on the printing paper 37 in the process of passing between the outer peripheral wall 53 of the drum 26 and the press roll 35. The printing paper 37 that has passed through between the outer peripheral wall 53 of the drum 26 and the press roll 35 is peeled off from the drum 26 by the paper separation claw 44, and the printing paper 37 that is separated from the drum 26 passes through the conveyance path 45. Then, the paper is discharged onto a paper discharge tray 46 and stacked there.

  During the printing operation, surplus ink that has flowed out downstream of the maximum printing area of the outer peripheral wall 53 flows into the ink collection port 72 of the ink collection unit 73 and is collected.

  When printing of the set number of prints is completed, the rotation of the outer peripheral wall 53 of the drum 26 is stopped and the drive of the ink supply means 54 is stopped. Thereby, the supply of the ink 56 to the outer peripheral wall 53 is stopped. The drive of the ink recovery means 73 is stopped slightly later than the stop of the ink supply means 54, and excess ink remaining on the outer peripheral wall 53 is recovered from the ink recovery port 72. Further, the press roll 35 is returned from the pressing position to the standby position and enters the standby mode.

  When the plate discharging process is started by starting a new plate making or the like, the base paper clamp portion 27 of the drum 26 is displaced to the clamp release position, and the leading end side of the stencil paper 18 that has been released from the clamp is conveyed as the drum 26 rotates. It is guided by the means 47 and is stored in the discharge box 48.

  As described above, in this stencil printing apparatus, the ink 56 is supplied to the outer peripheral wall 53 of the drum 26, and the ink 56 is diffused on the outer peripheral wall 53 by being squeezed by the pressing force of the press roll 35. The ink 56 is transferred to the printing paper 37 from the perforation of the stencil sheet 18 by the pressing force of the press roll 35. Then, excess ink that has not been used for printing on the outer peripheral wall 53 of the drum 26 is recovered by the ink recovery means 73, and the recovered excess ink is returned to the ink tank 57 of the ink supply means 54. Accordingly, it is possible to reliably suppress the situation where the excess ink is deteriorated on the outer peripheral wall 53 of the drum 26 to eliminate the waste of the ink 56 and to automatically use the collected ink 56 for the next printing. .

  In the above embodiment, since the ink supply means 54 and the ink recovery means 73 are always driven during the print mode, the ink 56 is continuously supplied from the ink supply port 55 to the outer peripheral wall 53 during the print mode. Since the ink 56 that has entered the ink recovery port 72 from the wall 53 is always recovered, it is possible to prevent the ink 56 from staying on the outer peripheral wall 56. In addition, since an appropriate amount of ink 56 can be always held on the outer peripheral wall 53, a printed matter having a desired ink density can be obtained even during a large amount of continuous printing.

  Further, at the end of the printing mode, the drive of the ink recovery means 73 is stopped slightly after the stop of the drive of the ink supply means 54, so that a substantially sealed space between the outer peripheral wall 53 of the drum 26 and the stencil sheet 18 is provided. It is possible to prevent excess ink from remaining. Even if surplus ink remains, the surplus ink 56 is held in a substantially sealed space between the outer peripheral wall 53 of the drum 26 and the stencil sheet 18, and contact with the atmosphere is minimized. Thereby, even if printing is not performed for a long time, the alteration of the surplus ink 56 can be reliably suppressed. Therefore, it is possible to further suppress the situation where the excess ink is deteriorated on the outer peripheral wall 53 of the drum 26, and it is possible to more effectively eliminate the waste of the ink 56.

  In the embodiment, the ink supply port 55 as an ink supply unit is provided at a print upstream position from the maximum print area of the outer peripheral wall 53, but may be provided at a print upstream position within the maximum print area of the outer peripheral wall 53. good. The print upstream position in the maximum print area where the ink supply port 55 is provided is literally the boundary between the maximum print area and the upstream non-print area, in addition to the print upstream position inside the maximum print area. It is a concept that includes the position. The print upstream position in the maximum print area where the ink supply unit is formed specifically means that the ink 56 supplied to the surface of the outer peripheral wall 53 has a maximum print area and a non-print area further upstream. It is the range which can be diffused at least on the partition line.

  In the above-described embodiment, the ink collection port 72 that is an ink collection unit is provided only at a position downstream of the maximum print area of the outer peripheral wall 53, but the ink collection is performed at the left and right outer positions in the printing orthogonal direction N of the maximum print area. A groove may be provided, and the ink collection groove may be continuous with the ink collection port 72. If comprised in this way, the ink which leaks from the side of the largest printing area can be collect | recovered, and the ink leakage from the side can be prevented. Further, an ink collection groove may be provided at a printing upstream position from the maximum printing area and at a printing downstream position from the base paper clamp unit 27, and the ink collection groove may be continued to the ink collection port 72. With this configuration, ink leaking from the top of the maximum printing area can be collected, and ink leakage from the top can be prevented.

  FIG. 6 shows a first modification of the ink recovery means of the embodiment, and is a schematic configuration diagram of the ink supply means and the ink recovery means.

  In FIG. 6, the ink recovery means 73A of the first modification has a vacuum (in which the other end of the fourth pipe 77 is connected to the ink tank 57 of the ink supply means 54 and the ink tank 57 is decompressed as an ink pump. A decompression pump 82 is used.

  In addition, since the other structure is the same as that of the said embodiment, the same code | symbol is attached | subjected to the same component and the detailed description is abbreviate | omitted.

  Even when the ink recovery means 73A of the first modified example is used, as in the above-described embodiment, it is possible to reliably suppress the situation where the excess ink is deteriorated on the outer peripheral wall 53 of the drum 26 and to waste the ink 56. In addition, the recovered ink 56 can be automatically used for the next and subsequent printing.

  FIG. 7 shows a second modification of the ink recovery means of the embodiment, and is a schematic configuration diagram of the ink supply means and the ink recovery means.

  In FIG. 7, the difference between the ink recovery means 73 </ b> B of the second modified example and that of the above embodiment is that the filter 80 for trapping paper dust and the like is interposed in the middle of the fourth pipe 77. To do.

  In addition, since the other structure is the same as that of the said embodiment, the same code | symbol is attached | subjected to the same component and the detailed description is abbreviate | omitted.

  Even when the ink recovery means 73B of the second modification is used, as in the case of the above-described embodiment, it is possible to reliably suppress the situation where the excess ink is deteriorated on the outer peripheral wall 53 of the drum 26 and to waste the ink 56. In addition, the recovered ink 56 can be automatically used for the next and subsequent printing.

  Ink collected from the outer peripheral wall 53 of the drum 26 passes through the filter 80, and impurities such as paper dust in the ink are trapped by the filter 80. Therefore, the quality of the recovered ink can be improved.

  FIG. 8 shows a third modification of the ink recovery means of the embodiment, and is a schematic configuration diagram of the ink supply means and the ink recovery means.

  In FIG. 8, in order to compare the ink collecting means 73 </ b> C of the third modified example with that of the first modified example, only a filter 80 that traps paper dust or the like is interposed in the middle of the fourth pipe 77. Is different.

  In addition, since the other structure is the same as that of the said embodiment, the same code | symbol is attached | subjected to the same component and the detailed description is abbreviate | omitted.

  Even in the case of using the ink collecting means 73C of the third modification, as in the above-described embodiment, it is possible to reliably suppress the situation in which the excess ink is deteriorated on the outer peripheral wall 53 of the drum 26 and to waste the ink 56. In addition, the recovered ink 56 can be automatically used for the next and subsequent printing.

  Ink collected from the outer peripheral wall 53 of the drum 26 passes through the filter 80, and impurities such as paper dust in the ink are trapped by the filter 80. Therefore, the quality of the recovered ink can be improved.

1 is a schematic configuration diagram of a stencil printing apparatus according to an embodiment of the present invention. 1 is a perspective view of a drum according to an embodiment of the present invention. FIG. 3 shows an embodiment of the present invention and is a cross-sectional view taken along line AA in FIG. 2. FIG. 3 shows an embodiment of the present invention and is a cross-sectional view taken along line BB in FIG. 2. FIG. 3 is a partial cross-sectional view illustrating an ink diffusion mechanism according to an embodiment of the present invention. FIG. 5 is a schematic configuration diagram of an ink supply unit and an ink recovery unit according to a first modification of the ink recovery unit of an embodiment of the present invention. FIG. 9 is a schematic configuration diagram of an ink supply unit and an ink recovery unit according to a second modification of the ink recovery unit of the embodiment of the present invention. FIG. 9 is a schematic configuration diagram of an ink supply unit and an ink recovery unit according to a third modification of the ink recovery unit of the embodiment of the present invention. It is the schematic of the principal printing part of the inner press system of a prior art example. It is the schematic of the ink supply means of the inner press system of a prior art example. It is the schematic of the printing principal part of the outer press system of a prior art example.

Explanation of symbols

18 Stencil Paper 26 Drum 35 Press Roll 37 Printing Paper (Printing Medium)
53 Outer peripheral wall 54 Ink supply means 55 Ink supply port (ink supply unit)
57 Ink tank 72 Ink collection port (ink collection unit)
73, 73A, 73B, 73C Ink recovery means

Claims (4)

A drum that is rotatable and has an outer peripheral wall formed of an ink impermeable member, a drum on which a stencil sheet is mounted, and an ink supply section on the outer peripheral wall of the drum; Ink supply means for supplying ink guided from an ink tank from the ink supply unit to the surface of the outer peripheral wall, and an ink recovery unit on the outer peripheral wall of the drum, and the surface of the outer peripheral wall from the ink recovery unit A stencil printing apparatus comprising ink collecting means for collecting surplus ink and a press roll for pressing a fed printing medium against the outer peripheral wall,
The stencil printing apparatus, wherein the ink collecting means is configured to return excess ink collected from the ink collecting section to the ink tank. The stencil printing apparatus according to claim 1,
A stencil printing apparatus, wherein a filter for trapping impurities in the ink is interposed in a path for returning ink from the ink recovery section to the ink tank. The stencil printing apparatus according to claim 1,
A stencil printing apparatus, wherein the ink supply means and the ink recovery means are always driven in a printing mode. The stencil printing apparatus according to claim 3,
The stencil printing apparatus, wherein at the end of the printing mode, the driving of the ink collecting unit is stopped slightly after the stop of driving of the ink supply unit.

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