JPH06297668A - Method and apparatus for producing thermal screen plate master - Google Patents

Abstract

PURPOSE:To produce a thermal screen plate master using a thermal screen plate manufacturing apparatus capable of obtaining a printing image free from character blur, solid filling-up inferiority, missing dots, fiber meshes, strike- through and printing durability deficiency. CONSTITUTION:A thermal head 14 equipped with a plurality of resistance heating elements 15 arranged in one row in a main scanning direction is brought into contact with a thermal screen plate master 11 and the thermal screen plate master 11 is relatively moved with respect to the thermal head 14 in the sub-scanning direction crossing the arrangement direction of the resistance heating elements 15 at a right angle and a perforated image is formed in a dot matrix system by selectively heating the resistance heating elements. By this method, the thermal screen plate master 11 is substantially composed only of a thermoplastic resin film and the width dimension of each of the connection parts not subjected to plate making formed between the perforations adjacent to each other in the main scanning direction formed on the thermal screen plate master 11 is set to 20% or more in pitch in the main scanning direction of the resistance heating elements.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive stencil plate making apparatus and a heat-sensitive stencil master for forming a perforated image in a dot-matrix type by using a thermal head for a heat-sensitive stencil master consisting essentially of a thermoplastic resin film. It relates to a plate making method.

[0002]

2. Description of the Related Art Conventionally, a heat-sensitive stencil master made of two layers by bonding a thermoplastic resin film layer having a thickness of about 2 μm and a porous support layer such as a Japanese paper base with an adhesive is A heat-sensitive plate making apparatus for perforating a plate in a dot matrix manner with a head is well known. As a thermal head used in this heat-sensitive plate making apparatus, JP-A-2-6713 is used.
Japanese Patent Laid-Open No. 3 (1993) introduces a resistance heating element having a dimension in the sub scanning direction shorter than a pitch in the main scanning direction. Further, Japanese Patent Laid-Open No. 4-45936 proposes a resistance heating element having a shape other than a rectangular shape.

In such a conventional heat-sensitive plate making apparatus, as shown in FIG. 9, a heat-sensitive stencil master 1 formed by laminating a thermoplastic resin film layer 1a and a porous support layer 1b is used. The heat-sensitive stencil master 1 is conveyed between the platen roller 3 and the thermal head 4, and the resistance heating element 5 provided on the thermal head 4 is in direct contact with the thermoplastic resin film layer 1a for punching.

[0004]

When a heat-sensitive stencil master composed of such a conventional thermoplastic resin film layer and a porous support layer is used for plate making, variations in the fibers of the porous support layer, that is, If the air gap between the fibers of the Washi paper base is too large, the thermoplastic resin film cannot be sufficiently brought into close contact with the resistance heating element of the thermal head, resulting in insufficient or unperforated holes. On the contrary, when the Washi paper-based fibers are dense, or when they are present as a lump, the heat is absorbed by the fibers and the holes are not sufficiently opened, or even if the holes are opened, the thermoplastic resin film Molten debris clings to the fibers. Further, when the thickness of the fibers of the Japanese paper base is thin, the thermoplastic resin film adheres too strongly to the resistance heating element, and the pores become too large. Therefore, as shown in FIG. 10, the holes 102 are not opened where they should be opened, the sizes of the holes 102 are varied, and the holes 102 are too large to be connected to the adjacent holes.

Therefore, problems such as blurring of characters, defective filling of solid images, white voids, fiber stitches, and show-through occur in printed images. In addition, there is a problem that, in the lumps of fibers of the Japanese paper base and in the portion where the adhesive is abundant, white spots in the solid portion, fiber stitches, and blurring of letters occur because the passage of ink is blocked.

[0006] Here, the white spots means a state where white dots where ink is not transferred are generated in a black solid printing portion, and the fiber stitches are a fiber pattern in which the white spots represent a fibrous lump state of a Japanese paper base. Character blurring is a phenomenon that some lines of fine characters are cut off.

In order to deal with the above problems, it was considered to remove the Japanese paper base which is the cause of the problem and use a heat-sensitive stencil master consisting essentially of a thermoplastic resin film. However, when a conventional heat-sensitive plate making apparatus is used to make a plate for a heat-sensitive stencil master that is essentially composed of a thermoplastic resin film, there is a problem that the heat-sensitive stencil master has insufficient printing durability. Here, the heat sensitive stencil master consisting essentially of a thermoplastic resin film,
In addition to those in which the heat-sensitive stencil master is made of only the thermoplastic resin film, those in which the thermoplastic resin film contains trace components such as an antistatic agent, and both main surfaces of the thermoplastic resin film, that is, at least the front surface and the back surface One includes one formed by forming one or a plurality of thin film layers such as an overcoat layer.

For example, when a master 100 having many horizontal lines (see FIG. 11) is used for plate making, the plate-made master 101 is shown in FIG.
As shown in FIG. 2, when the horizontal line portion B in FIG. 12 is enlarged, regular holes 102 are formed as shown in FIG. As shown in FIG. 12, the plate-making master 101 is wrapped around the outer peripheral surface of the cylindrical plate cylinder 103, one end of the master is fixed to the master clamper 104, and the printing paper is continuously pressed and transferred onto the master clamper 104, Print. At this time, the printing pressure of the press roller causes the arrow X on the plate-making master 101.
A tensile force acts in the direction. As a result, as shown in FIG. 14, the holes 102 punched in the plate-making master 101 expand and the printed line becomes abnormally thick. Generally, this line thickening is particularly likely to occur at the horizontal line portion B and the central portion D in FIG.

Further, by continuing printing, in the closed curve portion C in FIG. 12, there is a problem that the periphery thereof is broken and the portion of the thermoplastic resin film inside is peeled off from the outer peripheral surface of the cylindrical plate cylinder 103. In addition, in FIG. 12, the cylindrical plate cylinder 103 is developed and shown in a plan view.

The present invention can solve the above problems and provide a heat-sensitive stencil master having a sufficient printing durability, and can produce a printed image free from blurring of letters, poor filling of solid characters, white spots, fibers, and show-through. An object of the present invention is to provide a heat-sensitive stencil plate making apparatus which can be obtained and a heat-sensitive stencil master plate making method using the heat-sensitive stencil plate making apparatus.

[0011]

A method of making a heat-sensitive stencil master according to the present invention is characterized in that a thermal head comprising a plurality of resistance heating elements arranged in a line in the main scanning direction is brought into contact with the heat-sensitive stencil master to generate resistance heat. In a plate making method for forming a dot-matrix punched image by selectively heating the resistance heating element by moving the heat sensitive stencil master relative to the thermal head in the sub-scanning direction orthogonal to the direction in which the elements are arranged, Is substantially composed of a thermoplastic resin film, the width dimension of the unpress plate connection portion formed between the holes adjacent to each other in the main scanning direction formed in the heat-sensitive stencil master is the main scanning direction pitch of the resistance heating element. It is characterized by being 20% or more.

According to a second aspect of the present invention, there is provided a heat-sensitive stencil plate making apparatus in which a thermal head having a plurality of resistance heating elements arranged in a line in the main scanning direction is brought into contact with the heat-sensitive stencil master and is orthogonal to the arrangement direction of the resistance heating elements. In a heat-sensitive plate making apparatus that moves a heat-sensitive stencil master relatively to the thermal head in the sub-scanning direction to form a dot-matrix punched image by selective heating of resistance heating elements, the heat-sensitive stencil master is substantially heated. A thermal head is used which is composed of only a plastic resin film and in which the non-heating portion formed between the resistance heating elements adjacent to each other in the main scanning direction has a dimension in the main scanning direction of 30% or more of the main scanning direction pitch of the resistance heating elements. It is a composition.

Here, the sub-scanning direction means the conveying direction of the heat-sensitive stencil master, and the main scanning direction means the direction orthogonal to the sub-scanning direction.

[0014]

According to the plate making method of the heat-sensitive stencil master of the present invention, the heat-sensitive stencil master is formed substantially only of the thermoplastic resin film, and the unmade plate connecting portion formed between the adjacent resistance heating elements in the main scanning direction is formed. Since the width dimension is set to 20% or more of the pitch in the main scanning direction of the resistance heating element, the plate-made heat-sensitive stencil master can have sufficient strength, and the perforations corresponding to the original document are located at appropriate positions of the heat-sensitive stencil master. It can be opened securely. Even if this heat-sensitive stencil master is used for printing, it has sufficient printing durability, the perforated holes do not extend, and independent hole rows are maintained in both the main scanning direction and the sub-scanning direction. Therefore, the printed line does not become abnormally thick.

In the heat-sensitive stencil plate making apparatus of the present invention, the heat-sensitive stencil master is formed substantially only from the thermoplastic resin film,
Since the dimension in the main scanning direction of the non-heat generating portion formed between the resistance heating elements adjacent to each other in the main scanning direction is set to 30% or more of the pitch in the main scanning direction of the resistance heating elements, the perforation corresponding to the document is the heat sensitive stencil master. It can be opened securely in the proper position. Therefore, the same operation as that of the plate making method of the heat-sensitive stencil master can be obtained.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. Thermal stencil master 11 shown in the following drawings
The thickness of the plate-finished master 11a is exaggerated with respect to other members.

In FIG. 1, reference numeral 11 indicates a heat-sensitive stencil master. The heat-sensitive stencil master 11 is substantially made of a thermoplastic resin film having a thickness of 3 to 8 μm, and is made of polyester or the like. The heat-sensitive stencil master 11 passes between the platen roller 13 and the thermal head 14,
It is sent to the pair of transport rollers 12. This pair of transport rollers 12
Thus, the thermal stencil master 11 is pulled by the platen roller 13 while being pulled by a predetermined tension.
While being pressed against the resistance heating element 15, the platen roller 13 is conveyed by rotation in the arrow direction. The resistance heating element 15 of the thermal head 14 is brought into direct contact with the heat-sensitive stencil master 11, and the resistance heating element 15 selectively generates heat to perform hot-melt perforation.

As shown in FIG. 2, the thermal head 14 has a plurality of rectangular resistance heating elements 15 arranged in a line in the main scanning direction S at a constant pitch Pa. Electrodes 16 and 17 are connected to both ends of each resistance heating element 15 in the sub-scanning direction.

The main scanning direction pitch Pa of the mesh holes 18 formed in the heat sensitive stencil master 11 by the thermal head 14 is the same as the main scanning direction pitch Pa of the resistance heating elements 15 as shown in FIG. Pitch P in the sub-scanning direction
b is the feed pitch of the heat-sensitive stencil master 11 in the sub-scanning direction. In this embodiment, the main scanning direction pitch Pa and the sub scanning direction pitch Pb are set to be equal.

Main plate scanning direction unfinished plate connecting portion 19 formed between holes 18 adjacent in the main scanning direction S of the heat-sensitive stencil master 11.
If the width dimension c of the heat sensitive stencil master 11 is short (see FIG. 3),
The strength against the tensile force in the sub-scanning direction F decreases, and the printing durability of the heat-sensitive stencil master 11 becomes insufficient. On the contrary, width dimension c
If it is too long, there will be many areas where ink does not pass during printing, resulting in a decrease in density and white spots. Therefore, it is desirable to set the width dimension c to 20% or more and 50% or less, and more preferably 20% or more and 40% or less of the main scanning direction pitch Pa.

A sub-scanning direction unmade plate connecting portion 20 formed between holes 18 adjacent to each other in the sub-scanning direction F of the heat-sensitive stencil master 11.
For the above reason, the width e of the width e is preferably set to 20% or more and 50% or less, more preferably 20% or more and 40% or less of the sub-scanning direction pitch Pb.

In order to keep the width dimension c of the main scanning direction unengraved connecting portion 19 formed between each hole 18 in the main scanning direction S of the heat sensitive stencil master 11 to a certain length or more, It is desirable to set the width dimension d of each non-heating element portion 21 between the resistance heating elements 15 adjacent to each other in the scanning direction S to 30% or more and 65% or less of the main scanning direction pitch Pa, and more preferably 45. % To 65%.

As shown in FIG. 4, in the heat-sensitive stencil master 11,
The width dimensions c and e are applied to the above-mentioned range to form a hole 18
Was formed. When the cross section is enlarged, as shown in FIG.
Since the thickness t1 of the main scanning direction unprinted plate connecting portion 19 becomes thicker than the initial thickness t of the heat sensitive stencil master 11, the strength of the main scanning direction unprinted plate connecting portion 19 and the sub-scanning direction unprinted plate connecting portion 20 is , Becomes stronger than it looks. The thickness t1 of the main scanning direction unprinted plate connecting portion 19 and the sub-scanning direction unprinted plate connecting portion 20 in which the holes 18 are formed is about 2 to about 2 of the initial thickness t due to the heat melting shrinkage effect of the heat-sensitive stencil master 11. It triples. Therefore, the strength of the main scanning direction unmade plate connecting portion 19 and the sub-scanning direction unmade plate connecting portion 20 becomes strong, and the heat-sensitive stencil master 11
Printing durability is improved.

In the heat-sensitive stencil master 11, when the holes 18 are formed by heat-melting, the resin in the holes 18 is not vaporized but is attracted to the periphery of the holes 18 and rises. Occur. As described above, the thickness t1 of the main scanning direction unmade plate connecting portion 19 and the sub-scanning direction unmade plate connecting portion 20 of the heat-sensitive stencil master 11 is increased,
Sufficient printing durability can be obtained even with the heat-sensitive stencil master 11 that is substantially composed of a thermoplastic resin film.

As shown in FIG. 6, in the heat-sensitive stencil master 11,
Holes 1 are punched so that the width dimensions c and e are out of the above range.
8 was formed. When the cross section is enlarged, as shown in FIG. 7, the central portion f of the four holes 18 rises, but the thickness t2 of the central portion f itself is not sufficient in the width dimensions c and e. It does not affect the tensile strength of the heat-sensitive stencil master 11.

The resistance heating element 15 configured as described above.
As shown in FIG. 8, the plate-making master 11a made by using the thermal head 14 having the above is wound around the outer peripheral surface of the porous cylindrical plate cylinder 22 with its tip fixed by the master clamper 23. The plate cylinder 22 is inside the plate cylinder 22.
An ink roller 24 for supplying ink to the inner peripheral surface of the sheet and a doctor roller 26 which is arranged in parallel with the ink roller 24 with a slight gap therebetween and forms an ink reservoir 25 with the ink roller 24 are arranged. There is.

After the plate-making master 11a is wound around the outer peripheral surface of the plate cylinder 22, the printing process is started. First, one sheet of printing paper 27 is fed to a registration roller (not shown) by a paper feeding device (not shown), and the registration drum (not shown) and the press roller 28 move at a predetermined timing in synchronization with the rotation of the plate cylinder 22. The printing paper 27 is inserted between the two. Then, the press roller 28 separated from the outer peripheral surface of the plate cylinder 22 moves upward, and the printing paper 27 is pressed by the plate-made master 11a wound around the outer peripheral surface of the plate cylinder 22 rotating in the arrow Y direction. By doing, plate-making master 11
Ink is transferred from the perforated portion of a to the surface of the printing paper 27 and printed. At this time, the ink roller 24 also rotates in the same direction as the rotation direction of the plate cylinder 22, and the ink is transferred to the plate cylinder 2.
Supply to the inner peripheral surface of 2. And the printed printing paper 2
7 is peeled from the outer peripheral surface of the plate cylinder 22 by a peeling claw (not shown), and is discharged to a paper discharge tray (not shown). The so-called plate making is completed by printing the first sheet. Next, by the same operation as the above operation, a predetermined number of prints are sequentially and continuously performed.

At the time of printing, the plate cylinder 22 is driven to rotate at a high speed in the direction of the arrow Y, so that the plate-made master 11a is pulled in the direction of coming out of the master clamper 23. However, as described above, the width dimension c of the plate-made master 11a is changed. 20% or more and 50% or less of the main scanning direction pitch Pa, and 20% or more and 50% or less of the width dimension e of the sub scanning direction pitch Pb. The portions 19 and 20 do not extend and the holes 18 do not continue.

The present invention will be described below based on Examples and Comparative Examples. (Example 1) A thermosensitive stencil-type digital plate-making printing device (trade name, manufactured by Ricoh Preport Co., Ltd.) to which a thermal head of 400 dots / inch was applied was punched using a document with many horizontal lines under the following conditions. After plate making, continuous printing was performed at a speed of 120 sheets / min. Main scanning direction width dimension of non-heat generating element portion d = 33.5 μm Main scanning direction dimension of resistance heating element a = 30 μm Sub scanning direction dimension of resistance heating element b = 40 μm Main scanning direction pitch Pa = 63. 5 μm Pitch of resistance heating element in the sub-scanning direction Pb = 63.5 μm Thickness of heat-sensitive stencil master 2 μm (polyester film only) Applied power 0.09 W In this case, the perforations formed in the heat-sensitive stencil master are completely independent, The width dimension c between the adjacent holes in the main scanning direction is 15 to 20 μm, and the pitch Pa in the main scanning direction is 24 to 24 μm.
It became 31%. The width e between adjacent holes in the sub-scanning direction was also 24 to 31 μm. When this plate-made master was wound around a plate cylinder and printed, it was confirmed that even after printing 3000 sheets, almost no line thickening was found in the printed matter, and the master printing durability was sufficient. It was also found that when the width dimension c exceeds 50% of the pitch Pa in the main scanning direction, even if ink bleeding is used, the solid is not entirely black and the density is insufficient.

(Comparative Example) In order to compare with Example 1 described above, a thermal stencil type digital plate-making printing apparatus (trade name, manufactured by Ricoh Preport Co., Ltd.) to which the same 400-dot / inch thermal head as described above was applied was used. Under the conditions described above, perforation plate making was performed using a document having many horizontal lines, and then continuous printing was performed at a speed of 120 sheets / min. Width dimension d in the main scanning direction of the non-heat generating element portion d = 13.5 μm Main scanning direction dimension of the resistance heating element a = 50 μm Sub scanning direction dimension b of the resistance heating element b = 60 μm Main scanning direction pitch Pa = 63. 5 μm Pitch of resistance heating element in the sub-scanning direction Pb = 63.5 μm Thickness of heat-sensitive stencil master 2 μm (polyester film only) Applied power 0.16 W In this case, the holes formed in the heat-sensitive stencil master are completely independent. The width dimension c between the perforations adjacent to each other in the main scanning direction is 5 to 10 μm, and the dot pitch Pa in the main scanning direction is
Fell below 16%.

When this plate-making master is wound around the plate cylinder and printed, the horizontal line printed at the time of printing about 500 sheets becomes thick near the center of the leading part, and the master printing durability is insufficient. confirmed.

The results of Example 1 and Comparative Example 1 described above are shown in Table 1.

[0033]

[Table 1]

[0034]

As described above, in the plate making method of the heat-sensitive stencil master of the present invention, the width dimension of the unmade plate connecting portion formed between the holes adjacent to each other in the main scanning direction formed in the heat-sensitive stencil master is adjusted. Since the resistance heating element is set to 20% or more of the main scanning direction pitch, it is possible to provide a heat sensitive stencil master having a sufficient printing durability, and it is possible to obtain a printed image with no blurring of letters, poor filling of solid characters, white spots, fiber marks, or show-through. can get.

Further, in the heat-sensitive stencil plate making apparatus of the present invention, the dimension of the non-heating portion formed between the resistance heating elements adjacent in the main scanning direction in the main scanning direction is 3 in the main scanning direction pitch of the resistance heating elements.
Since the thermal head of 0% or more is used, the same effect as the above method can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of a heat-sensitive stencil plate making apparatus showing an embodiment of the present invention.

FIG. 2 is a plan view of a main part of a thermal head.

3 is a plan view of an essential part of a plate-making master punched by the thermal head shown in FIG.

FIG. 4 is a plan view of an essential part of another plate-making master.

5 is a sectional view taken along line VV of FIG.

FIG. 6 is a plan view of a main part of another plate-making master.

7 is a sectional view taken along line VII-VII in FIG.

FIG. 8 is a cross-sectional view of essential parts of a stencil printing machine to which an embodiment of the present invention is applied.

FIG. 9 is a sectional view of an essential part of a conventional heat-sensitive plate making apparatus.

FIG. 10 is an enlarged plan view of an essential part of a plate-made master that is plate-formed by applying a conventional heat-sensitive plate-making device.

FIG. 11 is a diagram showing a document.

FIG. 12 is a plan view of a plate-making master.

FIG. 13 is an enlarged plan view of an essential part of FIG.

FIG. 14 is an enlarged plan view of an essential part of the plate-made master after printing using the plate-made master that has been plate-formed by the conventional thermal plate-making device.

[Explanation of symbols]

 11 Heat Sensitive Stencil Master 11a Plate-Made Master 12 Conveying Roller 13 Platen Roller 14 Thermal Head 15 Resistance Heating Element 16, 17 Electrode 18 Holes 19 and 20 Plate Making Connection S Main Scanning Direction F Sub-scanning Direction

Claims (2)

[Claims] 1. A thermal head comprising a plurality of resistance heating elements arranged in a line in the main scanning direction is brought into contact with a heat-sensitive stencil master, and the heat-sensitive stencil is arranged in a sub-scanning direction orthogonal to the arrangement direction of the resistance heating elements. In a plate making method in which a master is moved relative to the thermal head and a perforated image is formed in a dot matrix manner by selective heating of the resistance heating element, the heat-sensitive stencil master consists essentially of a thermoplastic resin film. A heat sensitive stencil master, wherein the width dimension of an unmade plate connecting portion formed between holes adjacent to each other in the main scanning direction formed in the heat sensitive stencil master is 20% or more of the main scanning direction pitch of the resistance heating elements. How to make a stencil master. 2. A thermal head comprising a plurality of resistance heating elements arranged in a line in the main scanning direction is brought into contact with a heat-sensitive stencil master, and the heat-sensitive stencil is arranged in a sub-scanning direction orthogonal to the arrangement direction of the resistance heating elements. In a heat-sensitive plate making apparatus that moves a master relative to the thermal head and selectively forms a perforated image in a dot matrix manner by selectively heating the resistance heating element, the heat-sensitive stencil master is substantially a thermoplastic resin film only. And a heat-sensitive stencil plate making apparatus using a thermal head in which a non-heating portion formed between adjacent resistance heating elements in the main scanning direction has a dimension in the main scanning direction which is 30% or more of the main scanning direction pitch of the resistance heating elements. .