JP2006347152A - Stencil printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make image quality higher by reducing variations in reproducibility even in the case of a high-resolution image such as a photographic image. <P>SOLUTION: This stencil printer controls a recording device so that a relationship between the number of dots capable of being pierced within one inch square and the ratio of a value acquired by subtracting an area, where a surface K on the other side of a surface, facing the recording device, of a thermoplastic resin film 61a-1 is pierced by the recording device, from an area where the surface F, facing the recording device, of the film 61a-1 is pierced by the recording device, to a value of the latter area can satisfy the expressions: Sp=(Sf-Sk)/Sf; and Sp≤0.0143×X<SP>0.2780</SP>. In the expression, Sp represents an area ratio; Sf represents the area of the pierced part, wherein the film 61a-1 is pierced, of the surface facing the recording device; Sk represents the area of the pierced part, wherein the film 61a-1 is pierecd, of the surface on the other side of the surface facing the recording device; and X represents the number of the dots capable of being pierced within one inch square. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  In the present invention, a heat-sensitive stencil sheet (hereinafter also simply referred to as a “master”) made on a peripheral surface of a printing drum is wound, and printing is performed by pressing a recording medium with a pressing means such as a press roller or a printing pressure means. The present invention relates to a stencil printing apparatus.

In a stencil printing apparatus, a porous printing drum (plate cylinder) having ink supply means inside a master that has been perforated by a recording device such as a thermal head based on data read from an original or data received from an external connection device The recording medium such as a printing sheet is pressed against the printing drum by a pressing means such as a press roller which is wound around the outer circumferential surface of the printing drum and is provided so as to be able to contact with and separate from the outer circumferential surface of the printing drum. Yes.
By the pressing (printing pressure) by the pressing means, the ink supplied to the drum inner peripheral surface oozes out through the drum opening portion and the master punching portion, and is transferred to the printing paper to form a printed image.
In general, a master having a laminate structure in which a thermoplastic resin film and a porous support made of Japanese paper or the like are joined with an adhesive is used.

Perforations formed by melting a thermoplastic resin film may be connected depending on the amount of heat and the resolution of the heat generating part of the recording device. If adjacent perforations are connected, the resolution of each dot is hindered and the image quality deteriorates. To do.
As described in Patent Documents 1, 2, 3, and the like, conventionally, improvements have been made to improve the independence of perforations. That is, in the past, the recognition that “independent perforation = good printing state” has been established.
In the perforated state, the surface of the thermoplastic resin film 61 a-1 in FIG. 13 that represents the cross-sectional shape of the heat-sensitive stencil sheet (hereinafter referred to as “F surface”) is outlined from the recording device side. When observed in the direction, it is represented as shown in FIG. In FIG. 13, reference numeral 61a-2 denotes a porous support.
The perforation diameter sizes Lm and Ls are preferably 45% to 80% with respect to the respective dot pitches Pm and Ps, and the perforation area S is preferably 20% to 50% of the product of the scanning pitches Pm and Ps. Yes.

JP 2001-322228 A JP 2001-322229 A JP 2001-322230 A

As described above, various techniques for improving the drilling state have been proposed. However, most of the conventional techniques focus on the separation (independence) of the perforations, and the stability of the printed image quality, which is the final output of the stencil printing apparatus, has not been considered.
In many conventional stencil printing apparatuses, a character image or a solid image occupies a large ratio, and if the perforated state of the F surface is separated, that is, independently perforated, the amount of ink supplied from one perforated dot is small. Even if there is a variation, it is often covered by the transfer of ink supplied from other punched dots adjacent to the punched dot, so the variation in the transfer amount of ink supplied from one punched dot part is less important. There was no problem even if I did not.
Therefore, as described above, it is only necessary to define the perforation state by the size of the perforation diameter or the perforation area with respect to the dot pitch, and select the ink corresponding to the perforation diameter.

However, in recent years, there has been an increase in the number of images mixed with photographic images due to high definition and the spread of digital devices and the flow of color printing, and there is a need for expression in units of dots more than ever.
Nevertheless, without considering the variation in the transfer amount of the ink supplied from one perforated dot, perforation was performed on the heat-sensitive stencil sheet under the control conditions based on the above-described conventional knowledge (recognition), and the printing drum The ink is transferred to the printing paper and printing is performed.
For this reason, the image reproducibility of the solid image and the dot dense portion is not so much a problem for the above-described reason, but in the printed matter when the plate is made in the plate making mode corresponding to the photographic image and the portion corresponding to the photographic image, There is a problem that variation in reproducibility becomes large.

  The main object of the present invention is to provide a stencil printing apparatus in which high-definition images such as photographic images have little variation in reproducibility and high image quality can be obtained.

  In order to achieve the above object, according to the first aspect of the present invention, a heat-sensitive stencil sheet having at least a thermoplastic resin film is perforated by a recording device, and the heat-sensitive stencil sheet thus made is formed on the outer peripheral surface of a printing drum. In a stencil printing apparatus which winds and supplies ink from the inside of the printing drum and performs printing by pressing a recording medium against the printing drum, the surface of the thermoplastic resin film facing the recording device is the recording device The area ratio occupied by the value obtained by subtracting the area perforated by the recording device from the surface opposite to the surface facing the recording device of the thermoplastic resin film from the area perforated by the resolution, And graphing the area ratio and printing variation ratio under each condition by changing the energy supply to the recording device Then, a value that can suppress the printing variation between the respective resolutions is extracted from the graph to obtain a relational approximate expression between the number of punchable dots of the recording device and the area ratio, and based on the area ratio and the relational approximate expression The recording device is controlled.

In the invention described in claim 2, a heat-sensitive stencil sheet having at least a thermoplastic resin film is perforated and made by a recording device, the plate-formed heat-sensitive stencil sheet is wound around the outer peripheral surface of the printing drum, In a stencil printing apparatus for supplying ink from the inside and pressing a recording medium against the printing drum for printing, the surface of the thermoplastic resin film facing the recording device is relative to the area perforated by the recording device. The ratio of the area obtained by subtracting the area perforated by the recording device from the surface opposite to the surface facing the recording device of the thermoplastic resin film, and the number of dots that can be perforated per square inch, The recording device is controlled such that the relationship satisfies the following expression.
Sp = (Sf−Sk) / Sf (Formula 1)
Sp ≦ 0.0143 × X ^0.2780 (Formula 2)
Sp: area ratio Sf: area of the punched portion where the thermoplastic resin film on the surface facing the recording device is punched Sk: punched portion where the thermoplastic resin film on the surface opposite to the surface facing the recording device is punched Area X: Number of dots that can be drilled in 1 square inch

  In the invention described in claim 3, a heat-sensitive stencil sheet having at least a thermoplastic resin film is perforated by a recording device, the plate-formed heat-sensitive stencil sheet is wound around the outer peripheral surface of the printing drum, In a stencil printing apparatus that supplies ink from the inside and presses a recording medium against the printing drum to perform printing, the surface of the thermoplastic resin film that faces the recording device is the main part of the perforated part that is perforated by the recording device. A value obtained by subtracting the diameter in the main scanning direction from the diameter in the main scanning direction from the diameter in the main scanning direction from the diameter of the thermoplastic resin film opposite to the surface facing the recording device. Is determined by changing the resolution and the amount of energy supplied to the recording device. A graph showing the ratio, and extracting a value that can suppress printing variation between the resolutions from the graph to obtain an approximate expression of the relationship between the number of piercable dots of the recording device and the main scanning ratio, and the main scanning ratio and The recording device is controlled based on the relational approximate expression.

In the invention according to claim 4, a heat-sensitive stencil sheet having at least a thermoplastic resin film is perforated and made by a recording device, the plate-formed heat-sensitive stencil sheet is wound around the outer peripheral surface of the printing drum, and In a stencil printing apparatus that supplies ink from the inside and presses a recording medium against the printing drum to perform printing, the surface of the thermoplastic resin film that faces the recording device is the main part of the perforated part that is perforated by the recording device. A value obtained by subtracting the diameter in the main scanning direction from the diameter in the main scanning direction from the diameter in the main scanning direction from the diameter of the thermoplastic resin film opposite to the surface facing the recording device. The recording device is controlled so that the relationship between the ratio occupied by and the number of dots that can be punched per square inch satisfies the following formula: To.
Lmp = (Lmf−Lkm) / Lmf (Formula 3)
^Lmp ≦ 0.0009 × X ^0.4565 (Formula 4)
Lmp: Perforation diameter ratio in the main scanning direction Lfm: Diameter in the main scanning direction of the perforated portion where the thermoplastic resin film on the surface facing the recording device is perforated Lkm: Thermoplastic resin on the surface opposite to the surface facing the recording device Diameter in the main scanning direction of the perforated portion where the film is perforated X: Number of dots that can be perforated in one square inch

  In the invention described in claim 5, a heat-sensitive stencil sheet having at least a thermoplastic resin film is perforated and made by a recording device, and the plate-formed heat-sensitive stencil sheet is wound around the outer peripheral surface of the printing drum, In a stencil printing apparatus that supplies ink from the inside and presses a recording medium against the printing drum to perform printing, a surface of the thermoplastic resin film that faces the recording device is a sub-portion of a punched portion that is punched by the recording device. A value obtained by subtracting the diameter in the sub-scanning direction of the punched portion in which the surface opposite to the surface facing the recording device of the thermoplastic resin film is punched by the recording device from the diameter in the sub-scanning direction with respect to the scanning direction diameter. Is determined by changing the resolution and the amount of energy supplied to the recording device. A ratio is graphed, and a value that can suppress printing variation between the resolutions is extracted from the graph to obtain an approximate expression of the number of punchable dots of the recording device and the sub-scanning ratio, and the sub-scanning ratio and The recording device is controlled based on the relational approximate expression.

In the invention described in claim 6, a heat-sensitive stencil sheet having at least a thermoplastic resin film is perforated and made by a recording device, the plate-formed heat-sensitive stencil sheet is wound around an outer peripheral surface of the printing drum, In a stencil printing apparatus that supplies ink from the inside and presses a recording medium against the printing drum to perform printing, a surface of the thermoplastic resin film that faces the recording device is a sub-portion of a punched portion that is punched by the recording device. A value obtained by subtracting the diameter in the sub-scanning direction of the punched portion in which the surface opposite to the surface facing the recording device of the thermoplastic resin film is punched by the recording device from the diameter in the sub-scanning direction with respect to the scanning direction diameter. The recording device is controlled so that the relationship between the ratio occupied by and the number of dots that can be punched per square inch satisfies the following formula: To.
Lsp = (Lfs−Lks) / Lfs (Formula 5)
Lsp ≦ 0.0009 × X ^0.4565 (Formula 6)
Lsp: Perforation diameter ratio in the sub-scanning direction Lfs: Sub-scanning direction diameter of the perforated part in which the thermoplastic resin film on the surface facing the recording device is perforated Lks: Thermoplastic resin on the surface opposite to the surface facing the recording device Diameter in the sub-scanning direction of the perforated part where the film is perforated X: Number of dots that can be perforated in 1 square inch

  According to a seventh aspect of the present invention, in the stencil printing apparatus according to any one of the first to sixth aspects, the recording device is a thermal head including a plurality of heating elements arranged in a main scanning direction. It is characterized by that.

  According to an eighth aspect of the present invention, in the stencil printing apparatus according to any one of the first to sixth aspects, the heat-sensitive stencil sheet is substantially composed of only a thermoplastic resin film.

According to the first or second aspect of the present invention, it is possible to suppress a variation in the adhesion area of the ink transferred from the perforated portion to the printing paper, and thus it is possible to obtain a printed image with stable quality.
According to the invention described in claim 3 or 4, since it is possible to suppress a variation in the amount of the ink transferred from the perforated portion to the printing paper in the main scanning direction, it is possible to obtain a print image with stable quality. it can.
According to the invention described in claim 5 or 6, it is possible to suppress a variation in the amount of the ink transferred from the perforated portion to the printing paper in the sub-scanning direction, so that it is possible to obtain a print image with stable quality. it can.

According to the seventh aspect of the present invention, since the recording device is a thermal head, the cost of the recording device itself can be suppressed compared to a recording device such as a laser, and the control and mounting unit becomes relatively easy. The device cost can be reduced.
According to the eighth aspect of the present invention, since the heat-sensitive stencil sheet is substantially composed only of the thermoplastic resin film, when ink is transferred from the printing drum to the printing paper through the heat-sensitive stencil sheet. In addition, since it is not necessary to be affected by the support made of Japanese paper or Japanese paper and PET or PET alone, it is possible to further enhance the effect of suppressing variation in the amount of ink transferred to the printing paper.

A first embodiment of the present invention will be described below with reference to FIGS.
First, based on FIG. 1, the overall configuration of the stencil printing apparatus and the outline of the stencil printing process in this embodiment will be described.
A document reading unit 80 having an ADF function is provided in the upper part of the apparatus main body 50, and a printing drum unit 100 having a porous printing drum (plate cylinder) 101 is provided in the lower central part thereof. A plate making device 90 is provided on the upper right side of the printing drum unit 100, and a plate discharging device 70 is provided on the upper left side of the printing drum unit 100. In addition, a paper feeding device 110 is provided below the plate making device 90, a printing pressure unit 120 is provided below the printing drum unit 100, and a paper discharge unit 130 is provided below the plate discharging device 70.

Next, the printing operation of the stencil printing apparatus according to the above configuration will be described.
First, a document 60 having an image to be printed is placed on a document placing table (not shown) disposed at the top of the document reading unit 80, and a plate making start key on an operation panel (not shown) is pressed. Along with pressing of the plate making start key, a plate removing process is first executed. That is, in this state, the used master 61b used in the previous printing remains attached to the outer peripheral surface of the printing drum 101 of the printing drum unit 100.

When the printing drum 101 rotates counterclockwise and the rear end portion of the used master 61b on the outer peripheral surface of the printing drum 101 approaches the plate release peeling roller pair 71a, 71b, the plate release peeling roller pair 71a, 71b is rotating. One discharge plate peeling roller pair 71a scoops up the rear end portion of the used master 61b.
The used master 61b is a pair of discharge plate conveying belts 72a and 72b wound around a pair of discharge plate rollers 73a and 73b disposed on the left side of the pair of discharge plate peeling rollers 71a and 71b and the pair of discharge plate peeling rollers 71a and 71b. While being transported in the direction of the arrow Y1, it is discharged into the discharge plate box 74 and is peeled off from the outer peripheral surface of the printing drum 101 to complete the discharge plate process. At this time, the printing drum 101 continues to rotate counterclockwise. The used master 61 b that has been peeled and discharged is then compressed inside the plate discharging box 74 by the compression plate 75.

In parallel with the plate removal process, the document reading unit 80 reads the document. A document 60 placed on a document table (not shown) is exposed and read while being conveyed in the directions of arrows Y2 to Y3 by the rotation of the separation roller 81, the pair of front document transport rollers 82a and 82b, and the pair of rear document transport rollers 83a and 83b. To be served. At this time, when there are a plurality of documents 60, the separation blade 84 feeds them one by one from the lowest document. In reading the image of the original 60, the reflected light from the surface of the original 60 illuminated by the fluorescent lamp 86 is reflected by the mirror 87 while being conveyed on the contact glass 85, and is constituted by a CCD (charge coupled device) through the lens 88. This is performed by being incident on the image sensor 89.
The original 60 is read by a well-known reduction-type original reading method, and the original 60 from which the image has been read is discharged onto the original tray 80A. The electrical signal photoelectrically converted by the image sensor 89 is input to an analog / digital (A / D) conversion board (not shown) in the apparatus main body 50 and converted into a digital image signal.

In parallel with this image reading operation, plate making and plate feeding processes are performed based on the image information converted into digital signals. A roll-shaped masterless master 61 set at a predetermined portion of the plate-making apparatus 90 is pulled out of a roll state and is pressed against a thermal head 91 as a recording device via the master 61, and a tension roller The pair 93a, 93b is transported to the downstream side of the transport path.
A plurality of minute heating resistors arranged in a line on the thermal head 91 with respect to the master 61 transported in this way are each in response to a digital image signal sent from an A / D conversion board (not shown). The thermoplastic resin film of the master 61 that selectively generates heat and is in contact with the generated heating resistor is melt-pierced.
In this way, image information is written as a drilling pattern by position-selective melt drilling of the master 61 according to the image information.

  The leading end of the master-making master 61a on which image information has been written is fed toward the outer peripheral side of the printing drum 101 by a pair of feed rollers 94a and 94b, and the traveling direction is changed downward by a guide member (not shown). The printing drum 101 in the plate feeding position state hangs down toward the expanded master clamper 102 (indicated by a virtual line). At this time, the used master 61b has already been removed from the printing drum 101 by the plate discharging process.

  When the front end of the master-making master 61a is clamped by the master clamper 102 at a fixed timing, the printing drum 101 is gradually wound around the outer peripheral surface while the printing drum 101 rotates in the direction A (clockwise direction). Go. The rear end portion of the master-making master 61a is cut into a fixed length by a cutter 95.

When one plate-made master 61a is wound around the outer peripheral surface of the printing drum 101, the plate-making and plate-feeding steps are finished, and the printing step is started. First, the uppermost one of the printing sheets 62 as the sheet-like recording medium stacked on the sheet feeding table 51 is sent out in the direction of arrow Y4 by the sheet feeding roller 140 toward the registration roller pair 142, and The registration roller pair 142 is sent to the printing pressure portion (image transfer portion) 120 at a predetermined timing synchronized with the rotation of the drum portion 100. When the fed printing paper 62 comes between the printing drum 101 and the press roller 103 as a pressing member, the press roller 103 that is spaced below the outer peripheral surface of the printing drum 101 is moved upward by a printing pressure applying mechanism (not shown). Is moved by the pre-made master 61 a wound around the outer peripheral surface of the printing drum 101.
Thus, ink oozes out from the opening portion of the printing drum 101 and the perforation pattern portion (both not shown) of the master-making master 61a, and the oozing ink is transferred to the surface of the printing paper 62 to form a printed image. The The first printing after the plate feeding process may be referred to as printing.

On the inner peripheral side of the printing drum 101, ink is supplied from an ink supply pipe 104 to an ink reservoir 107 formed between the ink roller 105 and the doctor roller 106, in the same direction as the rotation direction of the printing drum 101, and Ink is supplied to the inner peripheral side of the printing drum 101 by an ink roller 105 that rolls in contact with the inner peripheral surface while rotating in synchronization with the rotation speed of the printing drum 101.
The press roller 103 is disposed outside the printing drum 101 at a position facing the ink roller 105.

The printing paper 62 on which a printing image is formed in the printing pressure unit 120 is peeled off from the printing drum 101 by the paper discharge peeling claw 114 and sucked by the suction fan 118, while the suction paper discharge inlet roller 115 and the suction paper discharge outlet roller. 116, the conveyance belt 117 wound around 116 rotates in the counterclockwise direction, is brought into close contact with the conveyance belt 117 and conveyed toward the sheet discharge unit 130 as indicated by an arrow Y5, and is sequentially discharged and stacked on the sheet discharge table 52. Is done. In this way, so-called trial printing is completed.
Next, when the number of prints is set with a numeric keypad (not shown) and a print start key (not shown) is pressed, the steps of paper feeding, printing and paper discharge are repeated for the set number of prints in the same process as the trial printing. All the processes of stencil printing are completed.

Next, the process of realizing the present invention by focusing on the drilled state of the master 61 will be described.
Conventionally, it has been considered that the perforated state of the pre-mastered master 61a is as shown in FIG. 14, but the actual perforated state is as shown in FIG. 2 when the F surface is observed from above. It has become.
As shown in FIG. 2B, which is a cross-sectional view taken along the line DD in FIG. 2A, the perforated (melted) area of the F-surface thermoplastic resin film 61a-1 is defined as the maximum area (Sf). The perforated area gradually decreases as it approaches the K plane, and has a mortar shape in which the perforated area of the thermoplastic resin film 61a-1 is the minimum area (Sk) on the K plane. In FIG. 2, reference numeral 61a-2 denotes a support.
Therefore, the cause of the variation in the image quality of the printed matter is that the transfer amount of the ink supplied from the printing drum 101 to the printing paper 62 varies, and the cause thereof is the transfer of ink from each punched dot. The investigation was carried out considering that the situation was uneven.

As a result, it was found that the difference was caused by the difference in the perforated state described later.
When plate making was performed under various conditions and the perforated state was confirmed, as shown in FIG. 3, the areas of Sf and Sf ′ which are the perforated areas of the thermoplastic resin film 61a-1 on the F surface in FIG. Are the same, but it has been found that there is a state where the areas of Sk and Sk ′, which are perforated areas of the thermoplastic resin film 61a-1 on the K surface, are different.
In other words, there is a difference in the ratio of the area S of the part indicated by the oblique lines (not the cross-sectional display) in FIG.
Further, in the drilling diameter, as in the drilling area, a difference is caused in the ratio of Lm and Lm ′ and Ls and Ls ′ to Lfm and Lfs.
Depending on the type of the heat-sensitive stencil sheet, as shown in FIG. 4 (FIG. 2 equivalent view) and FIG. 5 (FIG. 3 equivalent view), the thermoplastic resin film 61a-1 also has a mortar shape in the opposite direction on the support side. There are some that are. However, there is almost no influence, and it has been confirmed by experiments by the present inventors that there is no difference in the variation in the amount of ink transfer due to the difference in the perforated state (whether or not it is also a mortar on the support side). Has been.

Hereinafter, based on FIG. 2, the contents verified by experiments that the difference in the print image quality is caused by the difference in the punching state described above will be shown.
With respect to the perforated area Sf of the thermoplastic resin film 61a-1 on the F surface, the perforated area Sk of the thermoplastic resin film 61a-1 on the K surface is calculated from the perforated area Sf of the thermoplastic resin film 61a-1 on the F surface. The ratio occupied by the area S of the subtracted portion is Sp, and the verification of the influence on the printed matter due to the difference in Sp, and the perforated diameters Lfm and Lfs of the thermoplastic resin film 61a-1 on the F surface in each scanning direction The degree of influence due to the difference between Lmp and Lsp when the ratio of each value obtained by subtracting the perforated diameters Lkm and Lks of the K-surface thermoplastic resin film 61a-1 from the perforated diameters Lfm and Lfs is Lmp and Lsp. Verification was performed.
In this verification test, different perforation states are created by varying the energization pulse width (energy supply time) to the thermal head 91, and the perforation area Sf of the F-side thermoplastic resin film 61a-1 is the same state. Thus, the relationship between the energization pulse width and the applied power was obtained in a prior experiment, and the experiment was conducted.

The main test conditions and verification procedures are as follows.
Printing cycle: 10ms / l
Thermosensitive stencil paper: Satelio master Thermal head: A3-600dpi, A3-400dpi, B4-300dpi
Pulse width: Variable in 5 steps Applied power: Adjust to a value corresponding to each pulse width (Sf is adjusted to be equal)
Ink: Satelio ink Type 400
Printing paper: Inkjet printer paper Verification procedure: A heat-sensitive stencil sheet made under the above conditions is wound around a printing drum, printed on a Satelio A-400, and the resulting printed image sample is observed with an optical microscope. The image data was loaded into a PC as image data, and the image data was analyzed with image analysis software WinROOF manufactured by Mitani Corporation.
The test results are shown in Table 1. Each variation ratio is a value when the variation ratio in condition 1 is 1.
Although the value changes somewhat depending on the ink used, the variation ratio tends to remain the same. In this experiment, the ink used was selected to be optimal for the current system.
In addition, as the printing paper, since we wanted to focus only on the degree of influence of perforation, a paper with less ink bleeding was selected.

FIG. 6 shows the relationship between the area ratio and the printing variation ratio at each resolution. As can be seen from FIG. 6, when the area ratio Sp exceeds 300 dpi = 34%, 400 dpi = 40%, and 600 dpi = 50%, the increase amount of the print variation ratio increases (result 1).
FIG. 7 shows the relationship between the main scanning diameter ratio and the printing variation ratio at each resolution, and FIG. 8 shows the relationship between the sub-scanning diameter ratio and the printing variation ratio at each resolution.
As can be seen from FIG. 7 and FIG. 8, the relationship between the perforation diameter ratios shows the same tendency in both the main scanning direction and the sub scanning direction, and the perforation diameter ratio Lmp in the main scanning direction and the perforation diameter ratio Lsp in the sub scanning direction are respectively When 300 dpi = 16%, 400 dpi = 21%, and 600 dpi = 30% are exceeded, the amount of increase in the print variation ratio increases (Result 2).

Based on the above results 1 and 2, the relationship between the area ratio and the perforation diameter ratio that can suppress the printing variation between the respective resolutions was arranged, and the relationship as shown in FIG. 9 was obtained. That is, in the relationship between the number of piercable dots and the area ratio, an approximate expression (relational expression) of y = 0.0143 × X ^0.2780 is obtained, and in the relationship between the number of ^puncturable dots and the hole diameter ratio, y = 0. An approximate expression (relational expression) of .0009 × X ^0.4565 was obtained.
In FIG. 9, the number of dots that can be punched per square inch is, for example, when the resolution in the main scanning and sub-scanning directions is main scanning = 600 dpi and sub scanning = 600 dpi, 600 × 600 = 360000 [pieces].

A comparison was made between printing states when the resolution in the main scanning and sub-scanning directions was 400 dpi and the area ratio Sp was 22.6% and 43.5%. The results are shown in FIGS. As shown in FIG. 11, when the area ratio is 43.5%, the difference in printing state between dots is large.
Therefore, in the case of the above resolution, in order to obtain a printing state with little variation, the area ratio is preferably 40% or less in consideration of the relational expression obtained in FIG.
In condition 1 and condition 4 in Table 1, perforation is performed in the form of the combined area Sf of the perforated part in which the thermoplastic resin film on the surface that receives heat from the recording device is perforated, and printing of the printed matter for the same number of perforated dots As a result of comparing the areas, there was no difference in the average values of the two.
However, if the value of the area ratio Sp exceeds the value of the relational expression obtained in FIG. 9 as described above, that is, if the above (Expression 2) is not satisfied, the variation in the printing state becomes large.
Similarly, if the value of the perforation diameter ratio Lmp in the main scanning direction does not satisfy the above (Equation 4), the variation in the printing state increases. If the value of the perforation diameter ratio Lsp in the sub-scanning direction does not satisfy the above (Formula 6), the variation in the printing state becomes large.
Therefore, so as to satisfy the above (formula 1) and (formula 2), so as to satisfy (formula 3) and (formula 4), or so as to satisfy (formula 5) and (formula 6). The amount of energy supplied to the thermal head 91 is controlled.

The purpose of the present invention is to suppress variations in fixing the ink that has passed through the heat-sensitive stencil sheet, perforated from the printing drum, to the printing paper, and therefore does not define the size of the perforation itself.
The size of the perforation itself may be adjusted according to the conditions according to the characteristics of the use environment and printing paper.
Further, in the present invention, a verification experiment is performed and explained along an example using a thermal head. When the relationship between the energization pulse and the applied power for obtaining the same perforation state was investigated during the verification experiment, the relationship shown in FIG. 12 was obtained.
As can be seen from FIG. 12, since the applied power value increases exponentially as the pulse width is shortened, shortening the energization pulse is not very desirable from the viewpoint of the power resistance of the thermal head.

In the verification experiment, the energization pulse width is varied to cause a difference in the drilling state. Among them, the pulse width of Condition 1 where the variation ratio was the smallest was quite short, but the area ratio did not become zero.
Although the condition 1 was attempted to further reduce the pulse width under condition 1 to bring the area ratio closer to zero, it could not be realized within the operable range including the product life of the used thermal head.
From the above, in the stencil printing apparatus using the thermal head, it is considered impossible to make the hatched portion S shown in FIGS. 2 (a) and 3 (a) zero. .
In laser drilling, drilling can be performed so that the hatched portion S becomes almost zero, but there is a problem from the viewpoint of handling and an increase in apparatus cost.

  In the present embodiment, as the heat-sensitive stencil sheet, the one composed of the thermoplastic resin film 61a-1 and the support 61a-2 is exemplified, but the heat-sensitive stencil sheet substantially composed of only the thermoplastic resin film having no support. The same variation suppressing effect can be obtained even when using.

1 is a schematic front view of a stencil printing apparatus according to an embodiment of the present invention. It is a figure which shows the perforated part of a thermoplastic resin film, (a) is a top view from the side which faces a recording device, (b) is sectional drawing in the DD line in (a). It is a figure which shows the perforated part from which the conditions of a thermoplastic resin film differ, (a) is a top view from the side which faces a recording device, (b) is sectional drawing in the DD line in (a). It is a figure which shows the perforated part from which the conditions of a thermoplastic resin film differ, (a) is a top view from the side which faces a recording device, (b) is sectional drawing in the DD line in (a). It is a figure which shows the perforated part from which the conditions of a thermoplastic resin film differ, (a) is a top view from the side which faces a recording device, (b) is sectional drawing in the DD line in (a). It is a graph which shows the relationship between the area ratio in each resolution, and a printing variation ratio. It is a graph which shows the relationship between the main scanning diameter ratio and printing variation ratio in each resolution. 6 is a graph showing a relationship between a sub-scanning diameter ratio and a printing variation ratio at each resolution. It is a graph which shows the relationship between the number of dots which can be pierced, area ratio, and piercing diameter ratio. It is a figure which shows the printing state in the conditions 1, (a) is the elements on larger scale of (b). It is a figure which shows the printing state in the conditions 4, (a) is the elements on larger scale of (b). It is a graph which shows the relationship between the electricity supply pulse and applied electric power for obtaining the same perforation area. It is sectional drawing of a heat sensitive stencil paper. It is the top view seen from the side which faces a recording device of the perforated part made into the ideal in the past.

Explanation of symbols

61 Heat-sensitive stencil paper (master)
61a-1 Thermoplastic resin film 62 Printing paper as recording medium 91 Thermal head as recording device 101 Printing drum

Claims (8)

A thermosensitive stencil sheet having at least a thermoplastic resin film is perforated and made by a recording device, the engraved thermosensitive stencil sheet is wound around an outer peripheral surface of a printing drum, ink is supplied from the inside of the printing drum and a recording medium In a stencil printing apparatus that performs printing by pressing against the printing drum,
The surface opposite to the surface facing the recording device of the thermoplastic resin film from the area with respect to the area where the surface facing the recording device of the thermoplastic resin film is perforated by the recording device The area ratio occupied by the value obtained by subtracting the area perforated by the device is obtained by changing the resolution and the amount of energy supplied to the recording device, and the area ratio and the printing variation ratio under each condition are graphed. A value that can suppress printing variation between the respective resolutions is extracted to obtain a relational approximate expression between the number of piercable dots of the recording device and the area ratio, and the recording device is determined based on the area ratio and the relational approximate expression. A stencil printing apparatus characterized by controlling. A thermosensitive stencil sheet having at least a thermoplastic resin film is perforated and made by a recording device, the engraved thermosensitive stencil sheet is wound around an outer peripheral surface of a printing drum, ink is supplied from the inside of the printing drum and a recording medium In a stencil printing apparatus that performs printing by pressing against the printing drum,
The surface opposite to the surface facing the recording device of the thermoplastic resin film from the area with respect to the area where the surface facing the recording device of the thermoplastic resin film is perforated by the recording device The percentage of the value minus the area drilled by the device,
The relationship with the number of dots that can be punched in 1 square inch is
A stencil printing apparatus that controls the recording device so as to satisfy the following expression.
Sp = (Sf−Sk) / Sf (Formula 1)
Sp ≦ 0.0143 × X ^0.2780 (Formula 2)
Sp: area ratio Sf: area of the punched portion where the thermoplastic resin film on the surface facing the recording device is punched Sk: punched portion where the thermoplastic resin film on the surface opposite to the surface facing the recording device is punched Area X: Number of dots that can be drilled in 1 square inch A thermosensitive stencil sheet having at least a thermoplastic resin film is perforated and made by a recording device, the engraved thermosensitive stencil sheet is wound around an outer peripheral surface of a printing drum, ink is supplied from the inside of the printing drum and a recording medium In a stencil printing apparatus that performs printing by pressing against the printing drum,
The surface of the thermoplastic resin film that faces the recording device faces the recording device of the thermoplastic resin film from the diameter in the main scanning direction with respect to the diameter in the main scanning direction of a punched portion that is punched by the recording device. The main scanning ratio occupied by the value obtained by subtracting the diameter in the main scanning direction of the punched portion in which the surface opposite to the surface is perforated by the recording device is obtained by changing the resolution and the amount of energy supplied to the recording device. And graphing the main scanning ratio and the printing variation ratio thereof, extracting a value capable of suppressing the printing variation between the resolutions from the graph, and calculating an approximate relationship between the number of punchable dots of the recording device and the main scanning ratio And the recording device is controlled based on the main scanning ratio and the relational approximate expression. A thermosensitive stencil sheet having at least a thermoplastic resin film is perforated and made by a recording device, the engraved thermosensitive stencil sheet is wound around an outer peripheral surface of a printing drum, ink is supplied from the inside of the printing drum and a recording medium In a stencil printing apparatus that performs printing by pressing against the printing drum,
The surface of the thermoplastic resin film that faces the recording device faces the recording device of the thermoplastic resin film from the diameter in the main scanning direction with respect to the diameter in the main scanning direction of a punched portion that is punched by the recording device. The ratio of the surface opposite to the surface occupied by the value obtained by subtracting the main scanning direction diameter of the perforated part perforated by the recording device;
The relationship with the number of dots that can be punched in 1 square inch is
A stencil printing apparatus that controls the recording device so as to satisfy the following expression.
Lmp = (Lmf−Lkm) / Lmf (Formula 3)
^Lmp ≦ 0.0009 × X ^0.4565 (Formula 4)
Lmp: Perforation diameter ratio in the main scanning direction Lfm: Diameter in the main scanning direction of the perforated portion where the thermoplastic resin film on the surface facing the recording device is perforated Lkm: Thermoplastic resin on the surface opposite to the surface facing the recording device Diameter in the main scanning direction of the perforated portion where the film is perforated X: Number of dots that can be perforated in one square inch A thermosensitive stencil sheet having at least a thermoplastic resin film is perforated and made by a recording device, the engraved thermosensitive stencil sheet is wound around an outer peripheral surface of a printing drum, ink is supplied from the inside of the printing drum and a recording medium In a stencil printing apparatus that performs printing by pressing against the printing drum,
The surface of the thermoplastic resin film that faces the recording device faces the recording device of the thermoplastic resin film from the diameter in the sub-scanning direction relative to the diameter in the sub-scanning direction of a punched portion that is perforated by the recording device. The sub-scanning ratio occupied by the value obtained by subtracting the diameter in the sub-scanning direction of the perforated portion formed by the recording device on the surface opposite to the surface is obtained by changing the resolution and the amount of energy supplied to the recording device. A graph of the sub-scanning ratio and its printing variation ratio in the graph, and extracting a value capable of suppressing printing variation between the respective resolutions from the graph, and calculating an approximate relationship between the number of dots that can be punched in the recording device and the sub-scanning ratio And the recording device is controlled based on the sub-scanning ratio and the relational approximation formula. A thermosensitive stencil sheet having at least a thermoplastic resin film is perforated and made by a recording device, the engraved thermosensitive stencil sheet is wound around an outer peripheral surface of a printing drum, ink is supplied from the inside of the printing drum and a recording medium In a stencil printing apparatus that performs printing by pressing against the printing drum,
The surface of the thermoplastic resin film that faces the recording device faces the recording device of the thermoplastic resin film from the diameter in the sub-scanning direction relative to the diameter in the sub-scanning direction of a punched portion that is perforated by the recording device. The ratio of the surface opposite to the surface occupied by the value obtained by subtracting the sub-scanning direction diameter of the perforated part perforated by the recording device;
The relationship with the number of dots that can be punched in 1 square inch is
A stencil printing apparatus that controls the recording device so as to satisfy the following expression.
Lsp = (Lfs−Lks) / Lfs (Formula 5)
Lsp ≦ 0.0009 × X ^0.4565 (Formula 6)
Lsp: Perforation diameter ratio in the sub-scanning direction Lfs: Sub-scanning direction diameter of the perforated part in which the thermoplastic resin film on the surface facing the recording device is perforated Lks: Thermoplastic resin on the surface opposite to the surface facing the recording device Diameter in the sub-scanning direction of the perforated part where the film is perforated X: Number of dots that can be perforated in 1 square inch In the stencil printing apparatus according to any one of claims 1 to 6,
The stencil printing apparatus, wherein the recording device is a thermal head including a plurality of heating elements arranged in a main scanning direction. In the stencil printing apparatus according to any one of claims 1 to 6,
The stencil printing apparatus, wherein the heat-sensitive stencil sheet is substantially composed only of a thermoplastic resin film.

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