JPH08337039A - Plate cylinder for stencil printing apparatus - Google Patents

Abstract

PURPOSE: To provide a plate cylinder capable of producing clear printed images without unevenness in density for a stencil printing apparatus. CONSTITUTION: In a plate cylinder 1, rotating in the fixed direction with a stencil original sheet 8 wound around the outer circumferential surface and ink supplied from the inner circumferential surface, for a stencile printing apparatus, a support body 21 for forming the inner circumferential surface with a plurality of openings 21a formed thereto is provided, and grooves 21b, each leading from each of the openings 21a opened to the outer circumferential surface of the support body 21 to the upstream side in the direction or rotation, are formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate cylinder of a stencil printing machine.

[0002]

2. Description of the Related Art A stencil printing machine performs perforation making on a stencil sheet by a heating element of a thermal head, conveys the stencil sheet and winds it around the outer peripheral surface of the plate cylinder, and an ink supply means is provided to inner peripheral surface of the plate cylinder. The ink is supplied from the surface, and the paper is continuously pressed against the stencil sheet by a pressing means such as a press roller, and the ink is exuded from the inner peripheral surface of the plate cylinder to the outer peripheral surface and the perforated portion of the stencil sheet for printing. Is going.

The plate cylinder of such a stencil printing machine has a metallic cylindrical support such as stainless steel, and a mesh screen wound around the outer peripheral surface of the support. A large number of openings are formed in the support by etching or the like so that ink can be supplied from the inner peripheral surface to the outer peripheral surface.

Generally, in order to improve the unevenness of the printed image, it is sufficient to reduce the diameter and pitch of the openings and evenly supply the ink to the outer peripheral surface of the plate cylinder. In order to reduce the pitch and the pitch, the thickness of the support must be reduced, and the strength of the plate cylinder becomes weak. For this reason, as disclosed in Japanese Patent Publication No. 63-59393, a plurality of screens are wound around a support to uniformly distribute the ink on the outer peripheral surface of the plate cylinder. Further, as disclosed in JP-A-3-67682, a convex portion higher than the outer peripheral surface of the plate cylinder is provided around the opening of the outer peripheral surface of the plate cylinder, or a groove is formed so as to surround the opening. Was. Further, a technique has been proposed in which a porous body is provided on the outer peripheral surface of the support to uniformly supply the ink to the outer peripheral surface of the plate cylinder.

[0005]

The technique of providing a plurality of screens described above has a problem in that the ink flow is obstructed by the lines of the screen, the ink cannot be supplied uniformly, and uneven density occurs. In the case where the convex portion is provided, the stencil sheet comes into contact with the convex portion and is worn by frictional force when pressing the paper at the time of printing to open a hole, and the image is stained.
The problem that the position of the stencil sheet shifts is that there is a problem that in the case where the groove portion is formed, excessive ink is stored in the groove and uneven density occurs. In the technology that provides a porous material, it is necessary to use an ink with a very low viscosity, which causes image bleeding and adds an ink diffusion layer, so it takes time to start printing. There is a problem.

Therefore, the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a plate cylinder of a stencil printing apparatus which can obtain a clear printed image without density unevenness. .

[0007]

According to the first aspect of the present invention,
In the plate cylinder of the stencil printing machine, which is wrapped with a stencil sheet on the outer peripheral surface, is supplied with ink from the inner peripheral surface, and rotates in a fixed direction,
It has a support body in which a plurality of openings forming the inner peripheral surface are formed, and from each opening of the outer peripheral surface of the support body, a continuous groove is formed toward the upstream side in the direction of rotation. To do.

According to a second aspect of the present invention, the inner peripheral surface is formed in a plate cylinder of a stencil printing machine in which a stencil sheet is wound around the outer peripheral surface, ink is supplied from the inner peripheral surface, and rotates in a fixed direction. It is characterized in that it has a support body in which a plurality of openings are formed, and a continuous groove is formed from each opening on the inner peripheral surface of the support body toward the downstream side in the direction of rotation.

According to a third aspect of the present invention, the inner peripheral surface is formed in a plate cylinder of a stencil printing machine in which stencil sheet is wound around the outer peripheral surface, ink is supplied from the inner peripheral surface, and rotates in a fixed direction. A support having a plurality of openings formed therein, from each opening on the outer peripheral surface of the support, to the upstream side in the direction of rotation, and from each opening on the inner peripheral surface of the support to the downstream side in the direction of rotation. It is characterized in that continuous grooves are formed in and.

According to a fourth aspect of the present invention, in the plate cylinder of the stencil printing apparatus according to the first or third aspect, the groove continuous toward the downstream side in the rotation direction is branched into a plurality of grooves. Is characterized by.

According to a fifth aspect of the present invention, in the plate cylinder of the stencil printing apparatus according to the first or third aspect, the groove continuous toward the upstream side in the rotation direction forms a wide portion on the upstream side. It is characterized by

According to a sixth aspect of the present invention, the inner peripheral surface is formed in a plate cylinder of a stencil printing machine in which stencil sheet is wound around the outer peripheral surface, ink is supplied from the inner peripheral surface, and rotates in a fixed direction. It has a support body in which a plurality of openings were formed, and the opening is characterized in that the diameter of the support body on the inner peripheral surface side is larger than the diameter of the support body on the outer peripheral surface side.

[0013]

According to the first aspect of the present invention, since the continuous groove is formed from each opening on the outer peripheral surface of the support toward the upstream side in the rotation direction, the ink is uniformly dispersed from the opening of the support.

According to the second aspect of the present invention, since a continuous groove is formed from each opening on the inner peripheral surface of the support member toward the downstream side in the direction of rotation, a large amount of ink seeps out from the opening of the support member. .

According to the third aspect of the present invention, a groove is formed continuously from each opening on the outer peripheral surface of the support member toward the upstream side in the direction of rotation, and each groove is formed from each opening on the inner peripheral surface of the support member. Since a continuous groove is formed toward the downstream side in the direction, a large amount of ink oozes out from the opening of the support, and the diffusion of ink is promoted.

According to the fourth aspect of the invention, since the continuous groove is branched into a plurality of grooves, the ink is uniformly dispersed from the openings of the support.

According to the fifth aspect of the invention, since the wide width portion is formed on the upstream side of the groove, the ink is stored in the wide width portion, the ink supply source is formed between the openings, and the ink is formed on the outer peripheral surface of the support. Are evenly dispersed.

According to the sixth aspect of the invention, since the diameter of the support on the inner peripheral surface side is larger than the diameter of the support on the outer peripheral surface side, the thickness of the support can be increased and the opening The diameter and the pitch can be reduced, and the rigidity of the support increases even if the density of the openings is increased.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 represents a plate cylinder. As shown in FIGS. 1 and 2, the plate cylinder 1 includes a cylindrical support body 21 forming an inner peripheral surface, a screen 22 wound around the outer peripheral surface of the support body 21, and an outer peripheral surface of the plate cylinder 1. And a screen 23 that forms The plate cylinder 1 is rotatably supported around a rotation center shaft 5 that also serves as an ink pipe, which will be described later, and is rotated in a fixed direction by a motor.

The support 21 is formed of a metal such as stainless steel in a cylindrical shape, and has a clamp means 31 for clamping the front end of the stencil sheet 8 on its outer peripheral surface. The support 21 is provided with a plurality of openings 21a for allowing ink to pass through in a portion excluding the clamp means 31 and its peripheral portion and both side edge portions.

In each opening 21a on the outer peripheral surface of the support 21,
A continuous groove 21b is formed from each opening 21a toward the upstream side in the rotation direction of the plate cylinder 1, and each opening 21 on the inner peripheral surface of the support body 21 is provided on the downstream side in the rotation direction of the plate cylinder 1. A continuous groove 21c is formed toward it. The groove 21b is shown in FIG.
As shown in FIG. 3, the plate cylinder 1 is formed parallel to the rotation direction (indicated by an arrow in the figure).

These openings 21a and grooves 21 are formed in the support 21.
To form b and 21c, as shown in FIG. 3a, a mask 52 is placed on the back and front of the stainless steel thin plate 21 ', and the mask 52 shown in FIG.
As shown in FIG. 5, the grooves 21b and 21c may be formed by etching, and then the opening 21a may be etched. Further, the grooves 21b and 21c are formed by etching, and at the same time, the opening 21 is formed.
You may form a. Thereby, the opening 21a smaller than the conventional one can be formed.

The screen 22 is formed of a metal mesh screen or a foamed resin, and holds and allows ink to pass through. In this example, the screen 22
Although only one layer is provided, a plurality of layers may be provided.

The screen 23 is also formed similarly to the screen 22. The screens 22 and 23 are not limited to the above-mentioned ones, and mesh screens of a synthetic resin net,
It may be formed of a sintered sheet made by sintering metal fibers, a porous elastic sheet such as a porous rubber sheet, or a nonwoven fabric made of natural fibers or synthetic resin fibers. Further, although the screens 22 and 23 may be omitted and the plate cylinder may be configured only by the support 21, it is preferable to provide the plate cylinder for holding and diffusing ink.

The clamp means 31 is a stage 6 made of a magnetic material and provided along the generatrix of the outer peripheral surface of the support 21.
The clamper 7 is disposed at a portion facing the stage 6, is rotatably supported by the clamper shaft 7a, and has a magnet attached to the surface facing the stage 6.

Inside the plate cylinder 1, an ink roller 2 for supplying ink to the inner peripheral surface of the support 21 is arranged in parallel with the ink roller 2 with a slight gap between the ink roller 2 and the ink roller 2. A doctor roller 3 that forms an ink pool 4 and a rotation center shaft 5 that supplies ink to the ink pool 4 are arranged. The ink roller 2 and the doctor roller 3 are rotatably supported by side plates (not shown) in the plate cylinder 1 fixed to the rotation center shaft 5.

The ink is pressure-fed by an ink pump from an ink pack arranged at an appropriate position, and the rotation center shaft 5
The ink is supplied to the ink reservoir 4 through the supply hole 5a.

A press roller 16 for pressing the paper 15 against the plate cylinder 1 is provided below the outer peripheral surface of the plate cylinder 1 facing the ink roller 2, and a predetermined distance is provided between the press roller 16 and the outer peripheral surface of the plate cylinder 1. A pair of registration rollers 14 for feeding the sheet 15 at a timing is arranged.

The operation of the stencil printing machine configured as described above will be described. In FIG. 1, the plate-making stencil sheet 8 that has been plate-made is clamped at its leading end between the stage 6 and the clamper 7, and is wound around the outer peripheral surface of the plate cylinder 1. In this state, the plate cylinder 1 is rotated in a fixed direction, and one sheet of paper 1
5 is fed to the registration roller pair 14 and is wound around the outer peripheral surface of the screen 23 by the registration roller pair 14 at a predetermined timing synchronized with the rotation of the plate cylinder 1.
The paper 15 is inserted between the press roller 16 and the press roller 16.

At this time, the ink roller 2 also rotates in the same direction as the plate cylinder 1 rotates. The ink in the ink reservoir 4 is
The ink is attached to the surface of the ink roller 2 by the rotation of the ink roller 2, the amount of which is regulated when passing through the gap between the ink roller 2 and the doctor roller 3, and is supplied to the inner peripheral surface of the support 21.

The ink supplied to the inner peripheral surface of the support 21 is supplied from the groove 21c to the opening 21a by further rotation of the ink roller 2, as shown in FIG. Aperture 21
As shown by the arrow in the figure, the ink supplied to a is inclined and supplied to the upstream side in the direction of rotation of the plate cylinder 1 with respect to the opening 21a, and is supplied to the outer peripheral surface of the support 21 along the groove 21b. Spread. In addition, the ink is screen 22, screen 2
After being passed through the sheet 3, the stencil sheet 8 and the screen 23 are evenly supplied to the contact surface.

The press roller 16 separated from the outer peripheral surface of the plate cylinder 1 moves upward, and the paper 15 is pressed against the stencil sheet 8 wound around the outer peripheral surface of the screen 23 of the rotating plate cylinder 1. Thus, the ink is transferred from the perforations of the stencil sheet 8 to the surface of the sheet 15 and printed.

According to this example, since the groove 21b is provided, the ink is diffused from the opening 21a along the groove 21b, and the groove 21b is formed.
Due to the surface tension of the ink in b, the ink can be diffused to a portion apart from the opening 21a of the support 21 and the uneven density can be reduced. The degree of ink diffusion is measured by a microdensitometer (PDM5 type manufactured by Konica Corp.)
It was judged by measuring at.

Although this example is a combination of claim 1 and claim 2, in actuality, an effect that cannot be obtained by each element alone can be obtained. That is, by forming the grooves 21b and 21c in the opening 21a as in this example, an ink passage that obliquely communicates from the inside of the support 21 to the outside of the support 21 is generated or enlarged, and the ink roller 2 is formed. A part of the ink pressed by the support 21 is slanted with respect to the support 21.
Since the ink is moved to the outer peripheral surface of the ink and the diffusion of the ink to the outer peripheral surface of the support 21 is accelerated, the uneven density can be reduced.

Next, the inventor has found that the groove 2 continuous with the opening 21a.
A solid image is printed by using the support 21 having the 1c formed therein and a support having only openings having the same pitch and the same diameter as the support 21, and the pressure of the press roller 16 and the paper 15 at the time of solid printing are applied. The relationship with the ink supply amount was investigated. The result is shown in FIG. The curve X indicates the support 2 having the groove 21c formed therein.
In the case of 1, the curve Y represents the case of a support having only openings. As is clear from the figure, when the pressure of the press roller 16 is the same, the support 21 having the groove 21c can supply more ink than the support having only the opening.

When the pressing force of the press roller 16 can be reduced, the amount of deformation of the support 21 can be reduced and the thickness of the support 21 can be reduced. The fact that the thickness of the support 21 can be made thin means that the diameter and pitch of the openings 21a can be made small, and the variation in the ink supply amount depending on the location can be made small. Further, since the pressing force of the press roller 16 can be reduced, noise due to the collision of the press roller 16 can be reduced. Furthermore, since the amount of deformation of the support 21 becomes smaller,
The uneven density due to the bending of the support 21 does not occur.

FIG. 6 shows another support 41. Support 41
An opening 41a on the outer peripheral surface of the plate is provided with a groove 41b which is continuous to the upstream side in the direction of rotation of the plate cylinder 1 and which is branched into a plurality of grooves. According to this example, the ink is applied to the opening 41 of the support 41.
It is possible to diffuse from a along the groove 41b and reduce uneven density.

Further, another support 51 is shown in FIG. The opening 51a on the outer peripheral surface of the support 51 is provided with a continuous groove 51b on the upstream side in the direction of rotation of the plate cylinder 1, and the groove 51b is provided with a wide portion 51d for storing ink. . As described above, when the wide width portion 51d is provided, the ink supply source is auxiliary formed between the openings 51a, the ink can be diffused on the outer peripheral surface of the support 51, and the uneven density can be further reduced. In addition, a plurality of wide width portions 51d may be provided.

FIG. 8 shows a second embodiment of the present invention. An opening 61a is formed in the support 61 shown in this embodiment. The opening 61a has a diameter D1 on the inner peripheral surface side of the support 61.
Is formed to be larger than the diameter D2 on the outer peripheral surface side of the support body 61. Hereinafter, the diameter D1 portion of the opening 61a is referred to as a large diameter portion, and the diameter D2 portion is referred to as a small diameter portion. Opening 6
To form 1a, first, a mask is provided on the inner peripheral surface side of the support 61 to form a large diameter portion by half etching, and then another mask is used to form a small diameter portion. In addition,
To increase the rigidity of the support 61, the thickness t of the support 61 may be increased.

According to this example, the diameter D2 and the pitch of the openings 61a can be reduced while maintaining the rigidity of the support 61, and the ink can be evenly diffused on the outer peripheral surface of the support 61.

The inventor has found that a support 61 having an opening 61a having a large diameter portion and a small diameter portion, and a support having an opening having the same diameter on the inner peripheral surface and the diameter on the outer peripheral surface are formed. A solid image was printed by using, and the relationship between the ink supply amount per unit area and the position on the paper 15 and the relationship between the solid image density and the ink supply amount per unit area were examined. The results are shown in FIGS. 9 and 10. The solid image density is measured by the above-mentioned microdensitometer (PDM).
It was performed using a 5 type Konica Corporation.

A curved line X1 shown in FIG. 9 shows the case of the support 61 having an opening 61a having a large diameter portion and a small diameter portion.
The density unevenness at this time was 20%. On the other hand, the curve Y1 represents the case of a support body in which the diameter of the opening on the inner peripheral surface and the diameter of the opening on the outer peripheral surface are the same, and the density unevenness at this time was 40%.

In FIG. 10, the point A-A 'represents the distribution of the ink supply amount in the case of a support in which the diameter of the opening on the inner peripheral surface and the diameter of the opening on the outer peripheral surface are the same, and point B represents the distribution. −
Between B ′, the distribution of the ink supply amount in the case of the support 61 having the opening 61a having the large diameter portion and the small diameter portion is shown, and the point C shows the average ink supply amount of both. Points A1-A1 '
The interval B represents the density unevenness width in the case of a support in which the diameter of the opening on the inner peripheral surface and the diameter of the opening on the outer peripheral surface are the same.
Between 1 and B1 ′, the width of the uneven density in the case of the support 61 having the opening 61a having the large diameter portion and the small diameter portion, the point B1 is
The average density in the case of a support body in which the diameter of the opening on the inner peripheral surface is the same as the diameter of the opening on the outer peripheral surface, the point C1 is the support body 61 in which an opening 61a having a large diameter portion and a small diameter portion is formed. Represents the average concentration in the case of.

According to the present example, as is clear from FIGS. 9 and 10, a small amount of ink can be supplied from the densely arranged openings, the density difference of image unevenness is reduced, and at the same time, the pitch of unevenness of space is reduced. Since it shifts to the high frequency region, this unevenness is felt in the low sensitivity region of human spatial resolution,
A very calm image is obtained.

The stencil sheet 8 is a laminate type in which a porous support such as Japanese paper or a mixed paper of Japanese paper fibers and synthetic fibers is laminated with a thermoplastic resin film, or substantially only a thermoplastic resin film. It is also possible to use a base paper consisting of. A base paper consisting essentially of a thermoplastic resin film refers to a base paper consisting only of a thermoplastic resin film, a thermoplastic resin film containing a trace amount of components such as an antistatic agent, and a thermoplastic resin. The film includes one or more thin film layers such as an overcoat layer formed on both main surfaces of the film, that is, at least one of the front surface and the back surface.

In the case of a laminated type stencil sheet, since the porous support holds and diffuses the ink that has exuded from the opening of the support of the plate cylinder 1, the screens 22, 2 are
3 may be omitted. In the case of a stencil sheet containing only a thermoplastic resin film, the aperture ratio of the openings of the support is
The screens 22 and 23 may be omitted if they are large enough to diffuse the ink.

[0047]

According to the first aspect of the invention, since the continuous groove is formed from each opening on the outer peripheral surface of the support toward the upstream side in the rotation direction, the ink diffuses from the opening of the support, An image with less uneven density can be obtained.

According to the second aspect of the present invention, since a continuous groove is formed from each opening on the inner peripheral surface of the support toward the downstream side in the rotation direction, a large amount of ink seeps out from the opening of the support. The number of openings in the support can be reduced, and the rigidity of the support can be increased. Further, sufficient ink can be supplied even if the pressure of the press roller is lowered.

According to the third aspect of the invention, a groove is formed continuously from each opening on the outer peripheral surface of the support member toward the upstream side in the direction of rotation, and the groove is rotated from each opening on the inner peripheral surface of the support member. Since a continuous groove is formed toward the downstream side in the direction, a large amount of ink oozes out from the openings of the support, diffusion of the ink is promoted, and an image with less uneven density can be obtained.

According to the fourth aspect of the invention, since the continuous groove is branched into a plurality of grooves, the ink diffuses from the openings of the support, and an image with less uneven density can be obtained.

According to the fifth aspect of the present invention, since the wide portion is formed on the upstream side of the groove, the ink is stored in the wide portion and the ink supply source is formed between the openings, and the ink is formed on the outer peripheral surface of the support. Are uniformly dispersed, and an image with less uneven density can be obtained.

According to the sixth aspect of the present invention, since the opening having the diameter on the inner peripheral surface side of the support is larger than the diameter on the outer peripheral surface side of the support, the thickness of the support can be increased and the opening The diameter and pitch can be reduced, the rigidity of the support increases even if the density of the openings is increased, and an image with less uneven density can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of a stencil printer to which a plate cylinder according to a first embodiment of the present invention is applied.

FIG. 2 is a partially enlarged sectional view of a plate cylinder of the stencil printing apparatus shown in FIG.

FIG. 3 is a diagram illustrating a method of forming an opening of the support body shown in FIG.

FIG. 4 is a plan view showing an example of a groove continuous with an opening of a support.

FIG. 5 is a graph showing a relationship between an ink supply amount and a press roller pressure.

FIG. 6 is a plan view showing another support body.

FIG. 7 is a plan view showing still another support.

FIG. 8 is a sectional view of a support for a plate cylinder showing a second embodiment of the present invention.

FIG. 9 is a graph showing a relationship between an ink supply amount per unit area and a position on a sheet.

FIG. 10 is a graph showing a relationship between a solid image density and an ink supply amount per unit area.

[Explanation of symbols]

 1 plate cylinder 2 ink roller 3 doctor roller 5 rotation center shaft 6 stage 7 clamper 8 stencil base paper 14 registration roller pair 15 paper 16 press roller 21, 41, 51, 61 support 22 screen 23 screen 31 clamping means 21a, 41a, 51a, 61a opening 21b, 21c, 41b, 51b, 61b groove

Claims (6)

[Claims] 1. A plate cylinder of a stencil printing apparatus having an outer peripheral surface wound with a stencil sheet, supplied with ink from the inner peripheral surface, and rotating in a fixed direction, wherein a plurality of openings forming the inner peripheral surface are formed. A plate cylinder of a stencil printing machine, comprising a support, and a continuous groove is formed from each opening on the outer peripheral surface of the support toward the upstream side in the direction of rotation. 2. In a plate cylinder of a stencil printing machine in which an outer stencil sheet is wrapped around, stencil paper is supplied with ink from an inner peripheral surface and rotates in a fixed direction, a plurality of openings forming the inner peripheral surface are formed. A plate cylinder of a stencil printing apparatus, comprising a support, and a continuous groove is formed from each opening on the inner peripheral surface of the support toward the downstream side in the direction of rotation. 3. A plate cylinder of a stencil printing machine having an outer peripheral surface wound with a stencil sheet, supplied with ink from the inner peripheral surface, and rotating in a fixed direction, wherein a plurality of openings forming the inner peripheral surface are formed. A groove that is continuous from each opening on the outer peripheral surface of the support to the upstream side in the direction of rotation and from each opening on the inner peripheral surface of the support to the downstream side in the direction of rotation. A plate cylinder of a stencil printing machine characterized by being formed respectively. 4. The stencil printing machine according to claim 1 or 3, wherein the groove continuous toward the upstream side in the direction of rotation is branched into a plurality of grooves. Plate cylinder of the device. 5. The plate cylinder of the stencil printing apparatus according to claim 1 or 3, wherein the groove continuous toward the upstream side in the rotation direction forms a wide portion on the upstream side. Plate cylinder of stencil printer. 6. A plate cylinder of a stencil printing machine in which stencil sheet is wrapped around an outer peripheral surface, ink is supplied from the inner peripheral surface, and rotates in a fixed direction, a plurality of openings forming the inner peripheral surface are formed. A plate cylinder of a stencil printing apparatus, wherein the opening has a support, and the opening has a diameter on an inner peripheral surface side of the support that is larger than a diameter on an outer peripheral surface side of the support.