JP2009034840A - Stencil printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printer capable of suppressing the cost of components, retaining the compact property of the periphery of a pressing mechanism and effectively preventing re-transferring from the pressing mechanism to paper. <P>SOLUTION: This stencil printer is provided with a print drum 10 loaded with stencil paper N, and the pressing mechanism 11 facing the print drum 10 to freely abut thereon, clamps printing paper P by a picture formation part A between the print drum 10 and the pressing mechanism 11 and transcribes the picture on the stencil paper N on the printing paper P. The pressing mechanism 11 has a plurality of rollers 21, 22 and 23, and a mesh belt 24 laid across the plurality of rollers 21, 22 and 23 and moving between the rollers, wherein one press roller 21 out of the plurality of rollers 21, 22 and 23 is configured to push the mesh belt 24 toward the print drum 10. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a stencil printing apparatus provided with a plate cylinder on which a stencil sheet is mounted, and a pressing mechanism which is opposed to the plate cylinder so as to come into contact therewith.

  In this type of stencil printing apparatus, printing is performed by sandwiching a printing paper in an image forming unit between a printing cylinder on which the stencil paper is mounted and a pressing mechanism, and transferring an image of the stencil paper to the printing paper. In normal printing and paper transport processes, there is almost no possibility of ink on the plate cylinder side adhering to the pressing mechanism, and there is almost no possibility of retransfer of ink from the pressing mechanism to the back surface of the printing paper.

  However, due to non-feeding of paper to the image forming unit, wrong feeding timing, broken printing paper, etc., the printing cylinder side ink may adhere directly to the surface of the pressing mechanism during printing. When printing the other side of the printing paper on which one side has been printed, the ink may adhere to the surface of the pressing mechanism even when the ink on the one side is not sufficiently dry. When printing is continued in a state where the ink is attached to the pressing mechanism, the ink attached to the pressing mechanism is retransferred to the back surface of the printing paper, and the back surface of the printing paper becomes dirty.

  Further, in a stencil duplex printing apparatus provided with two sets of printing units composed of a plate cylinder and a pressing mechanism, one side of printing paper printed by one printing unit is placed on the surface of the pressing mechanism in the other printing unit. As in the case described above, when the ink is not sufficiently dried, the ink of the pressing mechanism adheres to the back surface of the paper and is retransferred to the paper. The paper becomes dirty.

In order to eliminate such retransfer of ink from the pressing mechanism to the printing paper, conventionally, a cleaning device for removing ink has been provided in the pressing mechanism to remove the ink adhering to the surface of the pressing mechanism (Patent Document) 1) and the surface of the pressure roller (pressing mechanism) is affixed with a mesh cloth, and the contact surface of the pressing mechanism with respect to the plate cylinder or printing paper is reduced by the uneven shape of the surface of the mesh cloth, and the ink adheres to the pressure roller. Printing apparatuses (such as Patent Document 2) with reduced amounts have been developed.
Japanese Patent Laid-Open No. 11-105401 JP 2002-219849 A

  In a printing apparatus provided with a cleaning device that removes ink adhering to the pressing mechanism, it is necessary to provide a cleaning device separately from the pressing mechanism, so that the cost increases and the arrangement space of the cleaning device must be secured. Don't be.

  In the printing apparatus in which the mesh cloth is attached to the surface of the pressure roller, the cost can be reduced and the compactness in the vicinity of the pressure roller can be maintained, but the amount of ink adhering to the mesh cloth increases during continuous printing. The adhering ink swells outward from the mesh cloth in the radial direction, increasing the possibility of retransfer to the printing paper and reducing the retransfer prevention effect.

(Object of invention)
An object of the present invention is to provide a printing apparatus capable of effectively preventing re-transfer from a pressing mechanism to a sheet while suppressing component costs and maintaining compactness in the vicinity of the pressing mechanism.

  In order to solve the above-described problems, the present invention includes a plate cylinder on which a stencil sheet is mounted, and a pressing mechanism that faces the plate cylinder so as to be in contact with the plate cylinder, and forms an image between the plate cylinder and the pressing mechanism. In the stencil printing apparatus for sandwiching the printing paper at the section and transferring the image of the stencil paper to the printing paper, the pressing mechanism includes a plurality of rollers and a mesh belt that is stretched between the plurality of rollers and moves between the rollers. The printing paper is pressed against the plate cylinder via the mesh belt by one of the plurality of rollers.

  According to the above configuration, since the uneven mesh belt is pressed against the plate cylinder side, the mesh belt makes point contact with the plate cylinder and the contact area becomes extremely small, so when the printing paper is not fed or the printing timing is shifted Alternatively, when the paper is folded, the amount (area) of ink adhering to the pressing mechanism can be greatly reduced, and thereby retransfer to the back side of the printing paper can be greatly reduced. In addition, since the mesh belt is temporarily separated from the surface of the roller by moving between a plurality of rollers, it is possible to prevent ink from accumulating at a specific portion of the mesh belt or the surface of the roller, thereby further re-transferring the ink. It can be effectively suppressed.

  According to the present invention, in the stencil printing apparatus having the above configuration, the mesh pitch of the mesh belt can be set in a range of 100 μm to 170 μm.

  When the mesh pitch is set in the above range, the contact area with the plate cylinder can be greatly reduced, while the pressing force during printing can be maintained uniformly, and printing can be performed without degrading the print quality.

  According to the present invention, in the stencil printing apparatus having the above configuration, the pressing mechanism is connected to a driving device, and the mesh belt is moved at a moving speed substantially the same as the peripheral speed of the outer peripheral surface of the plate cylinder by the rotation of the roller. Can be configured to.

  According to the above configuration, the rubbing phenomenon due to the difference between the peripheral speed of the plate cylinder and the moving speed of the mesh belt can be prevented, the printing surface can be prevented from being stained, and the printing quality can be improved.

  The present invention can be applied to a stencil duplex printing apparatus having a duplex printing mechanism.

  The stencil duplex printing apparatus includes, for example, two sets of printing units each composed of a plate cylinder and a pressing mechanism. One printing unit prints one side of the printing cylinder side of the printing paper, and the other printing unit prints the printed unit. Since one side abuts against the pressing mechanism, when using a slow-drying ink, there is a high possibility that ink will adhere to the pressing mechanism from the printed one side of the printing paper. In the present invention, if a pressing mechanism is provided that spans a mesh belt between a plurality of rollers as in the present invention, the function of preventing re-transfer of ink onto printing paper can be more effectively exhibited. .

  In the present invention, the circumference of the mesh belt can be set to a natural number times the circumference of the plate cylinder.

  According to the above configuration, since the total area of the mesh belt can be ensured, the density at which ink is attached to the pressing mechanism can be reduced, and in the case of a stencil duplex printing apparatus equipped with a double-sided printing mechanism, printing from the pressing mechanism is assumed. Even if retransfer to the paper occurs, the image retransferred from the pressing mechanism to the print paper matches the already printed image, and ghost does not occur.

  FIGS. 1 to 5 show an embodiment of the stencil printing apparatus according to the present invention. For convenience of explanation, as shown in FIG. The “side” and the downstream side of the paper feeding direction F are referred to as “front side”, and the paper width direction perpendicular to the paper transport direction is referred to as “left-right direction”.

[Overall structure of stencil printing machine]
FIG. 1 is a schematic side view of a stencil printing apparatus shown in perspective, and a printing apparatus main body 1 is provided with a paper feeding device 2 at the rear end and a paper tray 3 at the front end.

  In the printing apparatus main body 1, a printing unit 5 is arranged at an approximately middle part in the front-rear direction, a plate making apparatus 6 is arranged on the upper rear side of the printing unit 5, and a plate discharging apparatus 7 is arranged on the upper front side of the printing unit 5. An air suction type belt discharge device 8 is disposed in front of the image forming unit A of the printing unit 5.

  The plate making apparatus 6 makes a stencil sheet N with a thermal head 9 and attaches the stencil sheet N after the plate making to the plate cylinder 10 of the printing unit 5.

  The printing unit 5 includes the plate cylinder 10 that rotates in the R direction, and a pressing mechanism 11 that faces the lower end portion of the plate cylinder 10 so as to be able to come into contact with the lower side. The ink roller 12 is disposed on the image forming unit A formed between the lower end portion of the plate cylinder 10 and the upper end portion of the pressing mechanism 11, and the printing paper P is sandwiched between It is designed to print on the top surface.

  The plate discharging device 7 removes the used stencil sheet N mounted on the plate cylinder 10, takes it up by a take-up roller 13, and winds it up as a plate discharging roll 14.

  A pair of upper and lower timing rollers 15 are disposed in the vicinity of the rear portion of the printing unit 5, and rotate at an appropriate timing in synchronization with the driving of the plate cylinder 10, so that the printing paper P is fed to the image forming unit A of the printing unit 5. It comes to send.

  The sheet feeding device 2 includes a sheet feeding table 16, a front end abutting plate 17 erected substantially vertically on the front side of the sheet feeding table 16, and a scooping plate formed so as to rise forward at the upper end of the front end abutting plate 17. 18 and a rubber paper feed roller 19 that is opposed to the web 18 from above, and the front end portion of the uppermost printing paper P is sandwiched between the paper feed roller 19 and the web 18 The sheet feeding roller 19 rotates to supply the printing paper P to the timing roller 15 one by one.

[Pressing mechanism]
2 is a longitudinal sectional view of the printing unit 5 of FIG. 1, and FIG. 3 is a perspective view of the printing unit 5 of FIG. In FIG. 2, the pressing mechanism 11 includes a pressing roller 21 at the upper end extending in the left-right direction, a rotating roller 22 at the lower end disposed in parallel with the pressing roller 21, and an intermediate disposed in parallel with the pressing roller 21. A tension roller 23 and a mesh belt 24 wound around the three rollers 21, 22, 23 are provided, and the mesh belt 24 moves in the direction of arrow M. The upper and lower rollers 21 and 22 have substantially the same diameter, but the intermediate tension roller 23 is smaller in diameter than the upper and lower rollers 21 and 22. A guide plate 29 for guiding the rear surface of the mesh belt 24 in the middle of moving to the rotating roller 22 is disposed.

  In FIG. 3, the three rollers 21, 22, and 23 integrally have shaft portions 21 a, 22 a, and 23 a, and the shaft portions 21 a, 22 a, and 23 a each include a pair of left and right brackets 25. Is supported rotatably. The guide plate 29 is also fixed to the left and right brackets 25. A swing shaft 26 is fixed to the rear upper ends of the brackets 25. The swing shaft 26 is supported by a suitable fixing member of the apparatus main body 1 so as to be rotatable about an axis while not being shown in the drawing, and is attached to the drive device. The entire pressing mechanism 11 is swung up and down as indicated by arrows B1 and B2 around the axis of the swinging shaft 26, and the mesh belt is moved by the upper end pressing roller 21 when the pressing mechanism 11 is raised. 24 is pressed against the lower end of the plate cylinder 10.

  The pressing roller 21 is made of rubber, and the rubber hardness range is set to 25 degrees or more and 50 degrees or less.

  The left and right width of the mesh belt 24 is a dimension that substantially corresponds to the left and right width of the plate cylinder 10. The total length of the mesh belt 24 in the moving direction, that is, the circumferential length, is preferably set to a natural number multiple (1 times, 2 times, 3 times,...) Of the circumferential length of the plate cylinder 10. The circumference of the belt 24 is set to be the same as the circumference of the plate cylinder 10.

  Although not shown, the pressing roller 21 or the lower roller 22 is connected to a driving device such as a motor, and the mesh belt 24 is moved at the same speed as the peripheral speed of the plate cylinder 10 by the rotation of the pressing roller 21 or the like. It is configured to drive in the direction of arrow M.

  4 is an enlarged plan view of the mesh belt 24, and FIG. 5 is a VV cross-sectional view of the mesh belt 24 of FIG. In FIG. 4, the mesh belt 24 of this embodiment employs a plain weave cloth, and the mesh pitch D1 is set between 100 μm and 170 μm. As the vertical and horizontal fibers 24a and 24b used in the mesh belt 24, both metal fibers and synthetic fibers can be used. However, when durability is considered, metal fibers are used, and the pressing force is uniform. When increasing, it is preferable to use a synthetic fiber. In order to bring the mesh belt 24 into point contact as much as possible, a single wire is preferably used as the fiber 24a, 24b rather than a twisted wire (stranded wire).

  Further, the surface of the fibers 24a and 24b of the mesh belt 24 is preferably subjected to a water-repellent or oil-repellent coating with a silicone compound such as dimethyl silicone, polytetrafluoroethylene or fluoroalkylsilane or a fluorine compound. Thus, the adhesion of ink to the mesh belt 24 can be suppressed.

  In FIG. 5, the minimum height difference h in the cross section of the mesh belt 24, that is, the difference h between the upper end of the upper fiber 24 a and the upper end of the lower fiber 24 b in the fiber intersection portion is preferably set to 20 μm or more and 100 μm or less. . Thereby, even if ink adheres to the mesh belt 24, the ink can be stored in the vicinity of the intersection between the vertical fibers 24a and the horizontal fibers 24b to the extent that the ink is not retransferred from the mesh belt 24 to the printing paper.

[Action]
(1) In FIG. 1, a plurality of print sheets P stacked on a sheet feed table 16 of the sheet feeder 2 are sandwiched between a sheet feed roller 19 and a separating plate 18, and are fed at a predetermined sheet feed timing. As the sheet feeding roller 19 rotates, the sheet is supplied to the timing roller 15 one by one from the top.

(2) The timing roller 15 sends the printing paper P to the image forming unit A of the first printing unit 5 in accordance with the rotation angle (printing start position) of the plate cylinder 10.

(3) In the image forming unit A of the printing unit 5, the printing paper P and the mesh belt 24 are sandwiched from above and below between the plate cylinder 10 and the pressing roller 21 of the pressing mechanism 11, and the printing paper P is conveyed forward. While printing on the upper surface. The printed paper P is discharged from the belt discharge device 8 to the paper receiving tray 3.

[Effect of the embodiment]
(1) In FIG. 2, even when the printing paper P is not fed, the paper is folded, or the paper feeding timing is shifted during the printing operation, and the mesh belt 24 is in direct contact with the plate cylinder 10 (stencil paper N), Since the mesh belt 24 makes point contact with the lower end portion of the plate cylinder 10, the contact area is extremely small, and ink adhesion to the mesh belt 24 can be greatly reduced, whereby the mesh belt 24 is transferred to the printing paper P. Can significantly reduce re-transfer. In addition, the mesh belt 24 is temporarily separated from the surface of the pressing roller 21 by moving between the plurality of rollers 21, 22, and 23, so that ink is accumulated at a specific portion of the mesh belt 24 or the surface of the pressing roller 21. And the retransfer of the ink to the printing paper P can be more effectively suppressed.

(2) Even when printing on the other side of the printing paper P on which one side has already been printed, the adhesion of ink to the mesh belt 24 can be greatly reduced, and in this embodiment, the movement of the mesh belt 24 Since the speed is matched with the circumferential speed of the plate cylinder 10 and the circumferential length of the mesh belt 24 is matched with the circumferential length (all circumferences) of the plate cylinder 10, even if one side of the printing paper P is placed on the mesh belt 24, When the next printing paper is printed even if the next image is transferred, the image on one side of the next printing paper and the image transferred to the mesh belt 24 match, and a ghost is generated on the back surface of the printing paper. Can be prevented.

(3) Since the mesh pitch D1 of the mesh belt 24 is set in the range of 100 μm to 170 μm, the contact area with the plate cylinder 10 can be greatly reduced, while the pressing force during printing can be maintained uniformly and printing can be performed. You can print without losing quality.

(4) Since the rubber hardness range of the pressing roller 21 is set to 25 degrees or more and 50 degrees or less, the surface of the pressing roller 21 is meshed while maintaining the uniformity of the pressing force against the plate cylinder 10. It is possible to prevent ink from sticking out from the gap of the belt 24. That is, if the rubber hardness exceeds 50 degrees, it becomes too hard, the pressing force against the plate cylinder 10 may become uneven, and the print quality may be reduced. There is a possibility that the surface of the pressing roller 21 protrudes from the gap (rectangular space) of the mesh belt 24, the protruding portion contacts the ink, and the ink adheres to the surface of the pressing roller 21.

[Other embodiments]
(1) FIG. 6 shows an example in which the present invention is applied to a stencil duplex printing apparatus having a duplex printing function. The stencil duplex printing apparatus moves the first printing unit 35 and the second printing unit 36 in the front-rear direction. And a switchback type reversing path 37 composed of a plurality of air suction type belt conveying mechanisms is arranged in the conveying path between the printing units 35 and 36. Except for the structure in which the pair of printing units 35 and 36 and the reversing path 37 are provided, the configuration is the same as that of the first embodiment, and the same components are denoted by the same reference numerals.

The operation will be described.
1) The printing paper P of the paper feeding device 2 is sandwiched between the paper feeding roller 19 and the separating plate 18 and supplied one by one to the timing roller 15 from the top, and the timing roller 15 is a first printing unit. The printing paper P is sent to the image forming unit A1 of the first printing unit 35 in accordance with the rotation angle (printing start position) of the 35 plate cylinder 10.

  2) In the image forming unit A1 of the first printing unit 35, the printing paper P and the mesh belt 24 are sandwiched from above and below between the plate cylinder 10 and the pressing roller 21 of the pressing mechanism 11, and are placed on one side of the printing paper P. Printing is performed and discharged to the reversing path 37.

  3) In the reversing path 37, the printing paper P is turned upside down (front and back) and sent to the image forming unit A2 of the second printing unit 36.

  4) In the image forming unit A2 of the second printing unit 36, the printing paper P and the mesh belt 24 are sandwiched from above and below between the plate cylinder 10 and the pressing roller 21 of the pressing mechanism 11, and above the printing paper P. Printing is performed on the other side that faces, and it is sent to the belt discharge device 8.

  5) In the second printing unit 36, one side of the printing paper P printed by the first printing unit 35 contacts the mesh belt 24, but the mesh belt 24 makes point contact with the printed one side of the printing paper P. Therefore, the adhesion of ink to the mesh belt 24 can be greatly reduced. Further, by causing the moving speed of the mesh belt 24 to coincide with the circumferential speed of the plate cylinder 10 and the circumferential length of the mesh belt 24 to coincide with the entire circumference of the plate cylinder 10, even if the mesh belt 24 has the printing paper P Even if the one side image is transferred, when printing the next printing paper, the printed one side image of the next printing paper matches the image transferred to the mesh belt 24, so the back side of the printing paper There is no ghosting.

(2) In the embodiment described above, a plain weave mesh belt is used in order to make the contact area between the mesh belt and the plate cylinder as small as possible. However, as shown in FIG. A flat bottom woven mesh belt 24 can also be used as shown in FIG. When the flat bottom woven mesh belt 24 as shown in FIG. 8 is wound around the pressing roller 21, the flat bottom surface is pressed against the printing cylinder 10 or the printing paper so that the top surface protruding in an arc shape contacts the pressing roller. 21 is brought into contact with the surface.

(3) In the above embodiment, the driving device (not shown) for driving the pressing roller 21 and the mesh belt 24 of the pressing mechanism 11 is provided, but the present invention is also applied to a printing device that does not include the driving device. Can be applied. That is, the mesh belt 24 can be structured to follow the plate cylinder 10 rotating in the direction of the arrow R.

  The present invention is not limited to the above embodiments, and includes various modifications without departing from the scope of the claims.

1 is a schematic side view showing a stencil printing apparatus according to a first embodiment of the present invention in a see-through state. It is a longitudinal cross-sectional view of the printing unit 5 of FIG. It is a perspective view of the printing unit 5 of FIG. It is an enlarged partial top view of the mesh belt of the press mechanism of FIG. It is VV sectional drawing of FIG. It is a schematic side view which shows 2nd Embodiment of the stencil printing apparatus by this invention in a see-through state. It is a cross-sectional enlarged view which shows the modification of a mesh belt. It is a cross-sectional enlarged view which shows another modification of a mesh belt.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Printing apparatus body 5 Printing unit 10 Plate cylinder 11 Pressing mechanism 21 Pressing roller 22 Rotating roller 23 Intermediate tension roller 24 Mesh belt 26 Oscillating shaft 35, 36 1st, 2nd printing unit A, A1, A2 Image formation part P Printing paper

Claims (5)

A printing cylinder provided with a stencil sheet, and a pressing mechanism facing the printing cylinder so as to be in contact with the printing cylinder, and sandwiching the printing paper at an image forming portion between the printing cylinder and the pressing mechanism; In a stencil printing device that transfers images to printing paper,
The pressing mechanism includes a plurality of rollers and a mesh belt that is stretched between the plurality of rollers and moves between the rollers, and one of the plurality of rollers causes the mesh belt to pass through the mesh belt. A stencil printing apparatus characterized in that printing paper is pressed against the plate cylinder. In the stencil printing apparatus according to claim 1,
The stencil printing apparatus, wherein a mesh pitch of the mesh belt is set in a range of 100 μm to 170 μm. In the stencil printing apparatus according to claim 1 or 2,
A stencil printing apparatus, wherein the pressing mechanism is connected to a driving device, and the mesh belt is moved at a movement speed substantially the same as the circumferential speed of the outer peripheral surface of the plate cylinder by the rotation of the roller. In the stencil printing apparatus according to any one of claims 1 to 3,
A stencil printing apparatus having a duplex printing mechanism. In the stencil printing apparatus according to any one of claims 1 to 4,
The stencil printing apparatus according to claim 1, wherein the circumference of the mesh belt is set to a natural number times the circumference of the plate cylinder.

Images