JP2005125702A - Thermosensitive stencil master and stencil process printing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermosensitive stencil master which can inhibit the clogging of perforations and can make the best use of the advantage of its high density build in whatever stencil manufacturing pattern, and a stencil process printing device using this thermosensitive stencil master. <P>SOLUTION: The thermosensitive stencil master meets the conditions of 20%>X<SB>v2</SB>when the two-dimensional average area voids of a porous support in a specific area observed through from the thermoplastic resin film side, are X<SB>v2</SB>, using this master, a stencil is manufactured with the assistance of a thermal head 91 with a large number of heating resistors 218 and a glaze layer 213 whose thickness g is not more than 40 μm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a heat-sensitive stencil master and a stencil printing apparatus as printing plates in stencil printing.

The stencil printing apparatus has a heat-sensitive stencil master (hereinafter also simply referred to as “master”) punched and made by a thermal head based on data read from an original or received data from an externally connected device, and has an ink supply means inside. A recording medium such as printing paper is pressed against the printing drum by a pressing member such as a press roller which is wound around the outer circumferential surface of a porous printing drum (plate cylinder) and is provided so as to be in contact with and away from the outer circumferential surface of the printing drum. And print it.
By the pressing (printing pressure) by the pressing member, the ink supplied to the inner peripheral surface of the drum 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.

The thermal head has a plurality of minute heating resistors arranged in a line in the main scanning direction, and the secondary head orthogonal to the line direction of the heating resistor is in a state where the film surface of the master is in contact with the thermal head. Plate making is performed while relatively moving the master in the scanning direction. A dot-shaped plate-making image is formed on the master by position-selective heating of the heating resistor based on the image data.
The porous support is formed at a relatively low density, and there is a large amount of ink transferred (discharge amount) at the porous support, so that the ink adheres to the back side of the next printing paper before drying. There were problems such as transfer.
In recent years, the density of porous supports has been increasing in order to suppress the amount of ink transferred to prevent set-off and improve image quality.

Japanese Patent Laid-Open No. 10-24667 JP 2002-254844 A Japanese Patent No. 3188599

By increasing the density of the porous support, it is possible to reduce the variation in ink discharge amount, reduce the ink consumption, and improve the perforation probability by improving the surface smoothness on the surface of the master thermoplastic resin film. Therefore, it is possible to reduce white spots in the printed image and improve solid filling), and it can be expected to prevent set-off and improve image quality (high definition).
However, since higher density has been achieved, new problems have arisen especially at high resolution. A phenomenon occurs in which the drilling once opened during the drilling of the master is blocked (hereinafter referred to as “piercing blocking”). FIG. 12 (photocopy) shows a state in which perforation blockage has occurred.
According to the study by the present inventors, this perforation blockage is considered to occur from the relationship between the state of the porous support and the state of perforation of the thermoplastic resin film. In the conventional low density structure, when a specific position of the thermoplastic resin film is perforated, the melted portion escapes toward the porous support so that the perforation is clearly formed.

On the other hand, in the high-density configuration, the melted portion is less likely to escape toward the porous support, and conversely, the amount of escape toward the surface of the thermoplastic resin film increases. When the melted amount exceeds a certain amount, the melted portion exhibits a behavior that fills the perforated site, thereby causing perforation blockage.
For this reason, if the conventional thermal head is used for perforating plate making using the heat-sensitive stencil master having the above-described high-density configuration, the perforation blockage occurs, and the result is despite the increase in the density to improve the solid filling. As a result, in the case of an image having many solid images, the inferior solid filling is remarkable.

  Therefore, the present invention provides a heat-sensitive stencil master that can suppress the occurrence of perforation blockage and that can utilize the advantages of a high-density configuration in any plate-making pattern, and a stencil printing apparatus using the heat-sensitive stencil master. Objective.

In order to achieve the above object, according to the first aspect of the present invention, there is provided a position selective by a thermal head having a structure in which a thermoplastic resin film and a porous support are bonded together and having a plurality of minute heating resistors. In a heat-sensitive stencil master in which a dot-shaped plate-making image corresponding to image data is formed by gentle heating, the two-dimensional average area gap of the porous support in a specific area that is observed through from the thermoplastic resin film side when the rate was _{X V2,} and satisfies the condition of _{20%> X V2.}

The invention according to claim 2 has a structure in which a thermoplastic resin film and a porous support are bonded to each other, and according to image data by position selective heating by a thermal head having a plurality of minute heating resistors. In the heat-sensitive stencil master on which a dot-shaped plate-making image is formed, the two-dimensional average area porosity of the porous support in a specific area observed through the thermoplastic resin film side is represented by X _V2 , When the two-dimensional average area porosity calculated based on the void area of one heating resistor or less of the porous support in the area is X _V2R , 1%> X _V2 −X _V2R It satisfies the conditions.

  According to a third aspect of the invention, in the heat-sensitive stencil master of the first or second aspect, the thermoplastic resin film has a thickness of 1 μm or more.

  According to a fourth aspect of the present invention, in the heat-sensitive stencil master of the first or second aspect, the porous support has at least a porous resin film.

  In the invention according to claim 5, in the heat-sensitive stencil master according to claim 1 or 2, the porous support has at least Japanese paper made of chemical fibers or Japanese paper mixed with the above-mentioned chemical fibers and hemp. It is characterized by.

  In the invention according to claim 6, a thermal head is formed by forming a glaze layer on a thin film substrate bonded to a heat sink and forming a heating element on the glaze layer to form a plurality of minute heating resistors. In the stencil printing apparatus that performs the plate making according to the image data on the stencil master, winds the pre-made heat-sensitive stencil master around the outer peripheral surface of the printing drum, and supplies the ink from the inside of the printing drum to perform printing. The thickness of the glaze layer in the thermal head is 40 μm or less, and the heat-sensitive stencil master according to any one of claims 1 to 5 is used as the heat-sensitive stencil master.

  According to a seventh aspect of the present invention, in the stencil printing apparatus according to the sixth aspect, the bonding agent for bonding the thin film substrate to the heat radiating plate is a gel containing a material having a high thermal conductivity. And

  According to an eighth aspect of the present invention, in the stencil printing apparatus according to the seventh aspect, the material having a high thermal conductivity is a thermally conductive filler.

  According to a ninth aspect of the present invention, in the stencil printing apparatus according to the seventh or eighth aspect, the width of the gel agent in the sub-scanning direction is 3 mm or more.

  According to a tenth aspect of the present invention, in the stencil printing apparatus according to any one of the seventh to ninth aspects, the gel agent has a thickness of 120 μm or less.

  According to an eleventh aspect of the present invention, in the stencil printing apparatus according to any one of the sixth to tenth aspects, the thermal head temperature detecting means for detecting the temperature of the thermal head, and the thermal head temperature detecting means. It has a thermal head temperature perforation energy adjusting means for adjusting the perforation energy supplied to the heating resistor according to the detected value.

  According to a twelfth aspect of the present invention, in the stencil printing apparatus according to the eleventh aspect of the present invention, the stencil printing apparatus further comprises a calorific value correcting means for correcting the calorific value of the thermal head according to a detection value by the thermal head temperature detecting means, The heat generation amount correction control is performed at least once.

  According to a thirteenth aspect of the present invention, in the stencil printing apparatus according to any one of the sixth to tenth aspects, an energization number counting means for counting the number of energizations to the heating resistor, and the energization number counting means. There is provided a perforation energy adjusting means for each energization rate for adjusting the perforation energy supplied to the heating resistor in accordance with the number of energizations counted by the above.

  According to a fourteenth aspect of the present invention, in the stencil printing apparatus according to any one of the sixth to tenth aspects, an ink temperature detecting means for detecting an ink temperature, and a value detected by the ink temperature detecting means. And a punching energy adjusting means for each ink temperature for adjusting the punching energy supplied to the heating resistor.

  According to a fifteenth aspect of the present invention, in the stencil printing apparatus according to any one of the sixth to fourteenth aspects, the stencil printing apparatus further comprises an airflow forming means for forming an airflow in the vicinity of the thermal head. And

According to the first aspect of the present invention, image data is obtained by position-selective heating by a thermal head having a structure in which a thermoplastic resin film and a porous support are bonded together and having a plurality of minute heating resistors. in the heat-sensitive stencil master which is formed a dot-shaped perforated image corresponding to a two-dimensional average area porosity of the porous support in a particular area to be transmitted observed from the thermoplastic resin film side and X _V2 When
Since the condition of 20%> X _V2 is satisfied, excessive ink transfer can be suppressed, and thereby the set-off characteristic of stencil printing can be suppressed.
Further, since the surface smoothness on the surface of the thermoplastic resin film is improved, it is possible to suppress the occurrence of poor punching when melt punching with a thermal head, and it is possible to improve the quality of the printed image by reducing white spots.

According to the second aspect of the present invention, image data is obtained by position-selective heating by a thermal head having a structure in which a thermoplastic resin film and a porous support are bonded to each other and having a plurality of minute heating resistors. In the heat-sensitive stencil master that forms a corresponding dot-shaped plate-making image, the two-dimensional average area porosity of the porous support in a specific area that is permeated and observed from the thermoplastic resin film side is X _V2 , When the two-dimensional average area porosity calculated based on the void area of the heating support or less of the one heating resistor of the porous support in a specific area is _XV2R ,
_Since the condition of 1%> X _V2 -X _V2R is satisfied, excessive ink transfer can be suppressed, and thereby the set-off characteristic of stencil printing can be suppressed.
Further, since the surface smoothness on the surface of the thermoplastic resin film is improved, it is possible to suppress the occurrence of poor punching when melt punching with a thermal head, and it is possible to improve the quality of the printed image by reducing white spots.

  According to the invention described in claim 3, in the heat-sensitive stencil master according to claim 1 or 2, since the thickness of the thermoplastic resin film is 1 μm or more, it is resistant to elongation of the master peculiar to stencil printing. The effect of Claim 1 or 2 can be acquired, ensuring printability.

  According to the invention of claim 4, in the heat-sensitive stencil master of claim 1 or 2, since the porous support has at least a porous resin film, on the porous support side. A finer void can be obtained, and the effect of claim 1 or 2 can be further improved.

  According to a fifth aspect of the present invention, in the heat-sensitive stencil master according to the first or second aspect, the porous support has at least a Japanese paper made of chemical fibers or a Japanese paper mixed with the chemical fibers and hemp. Therefore, the strength (rigidity) and durability of the master can be improved.

According to the sixth aspect of the present invention, there is provided a thermal head in which a glaze layer is formed on a thin film substrate bonded to a heat sink and a heating element is formed on the glaze layer to form a plurality of minute heating resistors. A stencil printing apparatus that performs plate-making according to image data on a heat-sensitive stencil master, winds the pre-made heat-sensitive stencil master around the outer peripheral surface of the printing drum, and supplies ink from the inside of the printing drum to perform printing The thickness of the glaze layer in the thermal head is 40 μm or less, and the heat-sensitive stencil master according to any one of claims 1 to 5 is used as the heat-sensitive stencil master. Also in the original image, the perforation phenomenon can be suppressed, and the quality of the printed image can be further improved.
In addition, a low heat storage effect of the thermal head can be obtained, and this can improve a reduction in image reproducibility due to sticking.

  According to the invention described in claim 7, in the stencil printing apparatus according to claim 6, the bonding agent for bonding the thin film substrate to the heat radiating plate is a gel containing a material having high thermal conductivity. Therefore, the heat generated and accumulated in the thin film substrate can be efficiently radiated, and the low heat storage effect of the thermal head can be improved.

  According to the eighth aspect of the present invention, in the stencil printing apparatus according to the seventh aspect, since the material having a high thermal conductivity is a thermally conductive filler, the heat generated in the thin film substrate is efficiently used. Heat can be radiated and the low heat storage effect of the thermal head can be improved.

  According to the ninth aspect of the present invention, in the stencil printing apparatus according to the seventh or eighth aspect, since the width of the gel agent in the sub-scanning direction is 3 mm or more, the heat generated and accumulated in the thin film substrate Can be radiated more efficiently.

  According to the tenth aspect of the present invention, in the stencil printing apparatus according to any one of the seventh to ninth aspects, the gel agent has a thickness of 120 μm or less. The accumulated heat can be dissipated more efficiently.

  According to an eleventh aspect of the present invention, in the stencil printing apparatus according to any one of the sixth to tenth aspects, the thermal head temperature detecting means for detecting the temperature of the thermal head, and the thermal head temperature detection Since there is a thermal head temperature perforating energy adjusting means for adjusting the perforating energy supplied to the heating resistor according to the detection value by the means, high accuracy even if there is a temperature change of the thermal head A perforated state (high quality) can be obtained.

  According to a twelfth aspect of the present invention, in the stencil printing apparatus according to the eleventh aspect, the stencil printing apparatus further comprises a calorific value correcting means for correcting the calorific value of the thermal head in accordance with a value detected by the thermal head temperature detecting means. Since the heat generation amount correction control is performed at least once during the operation, a highly accurate punching state (high image quality) can be obtained over the entire printing operation even if the temperature of the thermal head changes. .

  According to a thirteenth aspect of the present invention, in the stencil printing apparatus according to any one of the sixth to tenth aspects, an energization number counting means for counting the number of energizations to the heating resistor, and the energization number In the case where the printing rate varies depending on the document image, since the punching energy adjusting unit for each energization rate is adjusted to adjust the punching energy supplied to the heating resistor according to the energization number counted by the counting unit. In addition, a highly accurate drilling state (high image quality) can be obtained.

  According to a fourteenth aspect of the invention, in the stencil printing apparatus according to any one of the sixth to tenth aspects, an ink temperature detecting means for detecting the temperature of the ink, and a detected value by the ink temperature detecting means. In response to the ink temperature, the perforating energy adjustment means for adjusting the perforating energy supplied to the heating resistor is provided, so that the ink temperature that affects the ink discharge amount (transfer amount) changes. However, the influence on the printed image can be suppressed, and the image quality can be improved.

  According to a fifteenth aspect of the present invention, in the stencil printing apparatus according to any one of the sixth to fourteenth aspects, the stencil printing apparatus further comprises an air flow forming means for forming an air flow in the vicinity of the thermal head. As a result, it is possible to suppress an increase in the ambient temperature in the plate-making part, to improve the heat dissipation of the thermal head, to prevent adverse effects due to heat storage, and to obtain a highly accurate drilling state (high image quality). .

Hereinafter, a first embodiment of the present invention will be described 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 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 heat-sensitive stencil master (hereinafter referred to as “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. Yes.

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 an ADF (not shown) is read for exposure while being transported in the directions of arrows Y2 to Y3 by 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. Provided. 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, non-plate-type heat-sensitive stencil master (hereinafter simply referred to as “master”) 61 set at a predetermined portion of the plate-making apparatus 90 is pulled out of the roll state and pressed by the thermal head 91 via the master 61. The platen roller 92 and the tension roller pair 93a and 93b rotate to be conveyed downstream of the conveying path.
A plurality of minute heating resistors (to be described later) arranged in a line on the thermal head 91 with respect to the master 61 conveyed in this manner are used as digital image signals sent from an A / D conversion board (not shown). In response, the thermoplastic resin film (described later) 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.
A fan 226 is provided as an air flow forming means for forming an air flow in the vicinity of the thermal head 91 obliquely above the thermal head 91. The heat stagnation generated in the thermal head 91 due to the air flow formation of the fan 226 is suppressed, and instability of drilling energy control due to heat storage is prevented. In the present embodiment, the fan 226 is provided as the air flow forming means. However, for example, an air flow of a suction fan 118 described later as existing equipment may be guided by a pipe and discharged to the thermal head 91.

  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 leading end of the master-making master 61a is clamped by the master clamper 102 at a fixed timing, the printing drum 101 gradually winds the master-making master 61a around the outer peripheral surface while rotating in the direction A (clockwise direction) in the figure. 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 papers 62 as recording media stacked on the paper feed tray 51 is sent out in the direction of the arrow Y4 by the paper feed roller 140 toward the registration roller pair 142, and further the registration rollers. The 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, the press roller 103 that has been separated below the outer peripheral surface of the printing drum 101 is moved upward, whereby the printing drum 101. The prepress master 61a wound around the outer circumferential surface is pressed. In this way, ink oozes out from the opening portion of the printing drum 101 and the perforation pattern portion (both not shown) of the pre-printed master 61a, and the oozing ink is transferred to the surface of the printing paper 62 to form a printed image. Is done. 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 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.

As shown in FIG. 2, the master 61 in the present embodiment has a thermoplastic resin film 204 and a porous support 205 attached to one surface side of the thermoplastic resin film 204. The porous support 205 has a porous resin film 206 made of a thermoplastic resin that is directly attached to the thermoplastic resin film 204 and a porous fiber film 208 that is attached to the porous resin film 206. doing. The porous fiber membrane 208 has at least a Japanese paper made of a chemical fiber such as PET (polyethylene terephthalate) or a Japanese paper made by mixing the chemical fiber and hemp.
The porous resin film 206 includes a resin film component 206a and a gap 206b. The porous resin film 206 is formed by precipitating and condensing a resin dissolved in a solvent, and has a structure having a large number of voids 206b inside and on the surface of the film. The thermoplastic resin film 204 has a thickness of 1 μm or more. The thickness of the thermoplastic resin film 204 is desirably 5 μm or less.

In more detail, the master 61 in the present embodiment, when the porous 2-dimensional average area porosity of the support 205 in a particular area to be transmitted observed from a thermoplastic resin film 204 side and the X _V2, 20 %> X _V2 is satisfied. Strictly speaking, the condition is 20%> X _V2 > 0%.
This is a state of the porous support 205, and the area S _K point that is the two-dimensional voids, the ratio of the area S _T of area to which the area S _K has been observed there in X _V2 , Indicating that the value is less than 20%. _XV2 is _{calculated |} required by following Formula.
X _V2 = S _K / S _T × 100 [%]
A specific measurement method will be described below. FIG. 3 is a copy of a photograph showing the flow of image analysis. In FIG. 3, master A shows a master having a porous resin film 206, and master B shows a master having only a porous fiber film 208.
With a two-dimensional image analyzer (Mitani Corporation: WinROOF), (1) The state of the porous support 205 is captured [FIG. 3 (a)], (2) The image is grayed [FIG. 3 (b) ], (3) Binarization is performed using a single threshold [FIG. 3 (c)]. (4) Since the voids may not be binarized with a small area due to the influence of pigments contained in the thermoplastic resin film 204 or the like, a hole filling process is performed [FIG. 3 (d)]. (5) Finally, the area ratio of the binarized portion in the arbitrary shape measurement is calculated. The contents were measured at several points and measured.

Further, the master 61 in the present embodiment has a two-dimensional average area porosity of the porous support 205 in a specific area that is permeated and observed from the thermoplastic resin film 204 side as X _V2 , and the porous support in the specific area. When the two-dimensional average area porosity calculated based on the void area below the heating area of one heating resistor 218 of the body 205 is _XV2R ,
It is formed so as to satisfy the condition of 1%> X _V2 -X _V2R . Strictly speaking, the condition is 1%> X _V2 −X _V2R ≧ 0%.
X _V2R represents an average void area ratio equal to or less than the area of the heating resistor 218 of the thermal head 91 (400 μm ² when the area of the heating resistor 218 is 20 × 20 μm), and X _V2 −X _V2R is The average void area ratio is calculated by subtracting the average void area ratio below the heating resistor area from the average void area ratio and calculating the average void area ratio above the heating resistor area.
A specific measurement method will be described below. With a two-dimensional image analyzer (Mitani Corporation: WinROOF), (1) The state of the porous support 205 is captured [FIG. 3 (a)], (2) The image is grayed [FIG. 3 (b) ], (3) Binarization is performed using a single threshold [FIG. 3 (c)]. (4) Since the voids may not be binarized with a small area due to the influence of pigments contained in the thermoplastic resin film 204 or the like, a hole filling process is performed [FIG. 3 (d)]. (5) The binarized place below the heating resistor area is deleted [FIG. 3 (e)]. (6) Finally, the void area ratio of the portion left after binarization by the arbitrary shape measurement is calculated. The contents were measured at several points and measured.

  FIG. 4 (photograph copy) shows the generation of voids when the porous support 205 has a porous resin film 206, and FIG. 5 (photocopy) shows that the porous support 205 contains only chemical fibers. The state of occurrence of voids in the case of comprising is shown.

The thermal head 91 is a type called the most general thin film line type thermal head. As shown in FIG. 6, an aluminum heat sink 210 as a heat sink, a ceramic substrate (may be an alumina substrate) 212 as a thin film substrate bonded to the aluminum heat sink 210 with a bonding agent 211, and the ceramic substrate A glaze layer 213 as a heat insulating layer formed on 212, a heating resistance layer 214 formed on the glaze layer 213, and a common electrode (common electrode) 215 provided on the heating resistance layer 214 And an individual electrode (lead electrode) 216 and a protective film 217 covering the upper surfaces thereof. Each heating resistor 218 is formed by the heating resistor layer 214 exposed between the common electrode 215 and the individual electrode 216.
The type of the glaze layer 213 is a full glaze type printed on almost the entire surface of the ceramic substrate 212. As the glaze material, glass, epoxy resin or the like can be considered, but in this embodiment, glass is used.

The thickness g of the glaze layer 213 is set to 40 μm or less. The thickness g of the glaze layer 213 is desirably 5 μm or more. The bonding agent 211 is a gel containing a silicon-based resin and a thermally conductive filler, and the width W of the bonding agent 211 applied to the lower surface of the ceramic substrate 212 in the sub-scanning direction (direction perpendicular to the main scanning direction) is It is set to 3 mm or more. Further, the thickness t of the bonding agent 211 is set to 120 μm or less. Strictly speaking, 0 <t ≦ 120 μm.
FIG. 7 shows a control configuration of the thermal head 91. A thermistor 219 serving as a thermal head temperature detecting means for detecting the temperature of the thermal head 91 is provided. The microcomputer 220 serving as a thermal head temperature perforating energy adjusting means detects the thermal head temperature (detection value) detected by the thermistor 219. ) Perforating energy supplied to each heating resistor 218 is adjusted. The microcomputer 220 has a known configuration including a CPU, a ROM, a RAM, an I / O interface, and the like.
In FIG. 7, reference numeral 221 denotes a power source, and the power source 221 supplies electric energy corresponding to the perforating energy for melting and perforating the thermoplastic resin film 204 of the master 61 to the thermal head 91 via a thermal head drive circuit (not shown). Supply.

In the ROM of the microcomputer 220, there is a relational data table of the stepwise thermal head temperature and the energization pulse width corresponding to the drilling energy for forming the drilling of the optimum size according to the change of the thermal head temperature. It is obtained and stored in advance by experiments or the like (including computer simulation). A voltage may be used instead of the energization pulse width (hereinafter the same).
The microcomputer 220 selects and sets the energization pulse width corresponding to the temperature information from the thermistor 219 from the data table.
As shown in FIG. 8, the thermistor 219 is disposed on a thermal head substrate 222 that is a circuit board on which the thermal head 91 is mounted, and detects the temperature of the main body of the thermal head 91. In FIG. 8, reference numeral 223 denotes a housing portion for the heating resistor 218.
The microcomputer 220 also functions as a heat generation amount correction unit that corrects the heat generation amount of the thermal head 91 according to the detection value of the thermistor 219, and performs heat generation amount correction control at least once during the plate making operation. The calorific value correction control is performed in the same manner as the drilling energy adjustment using the data table.

Below, the experimental result which confirmed the generation | occurrence | production probability of perforation | boring block | closed at the time of using the master 61 which satisfy | fills the conditions mentioned above and using the thermal head 91 in this embodiment (this invention) is shown.
[Experimental conditions]
Environment: 10 ° C, 20% Rh; 23 ° C, 65% Rh; 30 ° C 90% Rh
Line cycle: 2.083ms / L
Thermal head: (Conventional) Resolution: 600dpi
Heating resistor: aiming at 20 × 20μm
Glaze layer thickness: about 48μm
Gel thickness: aiming at 125μm
Gel agent bonding width: about 2mm
(Invention) Resolution: 600dpi
Heating resistor: aiming at 20 × 20μm
Glaze layer thickness: approx. 26μm
Gel thickness: 50μm
Gel bonding width: 7.3mm Target power: (Conventional) 0.0525W / dot
(Invention) 0.0550 W / dot
Energizing pulse width: (Conventional) 0.90 / 0.67ms; 0.77 / 0.60ms; 0.70 / 0 / 56ms
(Invention) 0/90/0 / 67ms; 0.75 / 0.57ms; 0.67 / 0.52ms
* Adjusting the thermal head structure and single unit variation based on the energization pulse width. Adjusting the power with plate power Pattern making: All dots ON x 420mm length Master: Thermoplastic resin film thickness: 2.0μm
Porous support: Japanese paper and porous resin made of chemical fiber (about 25μm)
Membrane (about 13μm)
_{X V2 = 19%, X V2} -X V2R = 0.2%
The results are shown in FIG.

In FIG. 9, the probability of occurrence of perforation blockage is calculated from the total number of dots made in a certain area and the number of dots where perforation blockage occurs.
Perforation blocking occurrence probability = number of perforation blocking dots / total number of dots × 100%
In the case of the above experimental example,
Perforation block occurrence probability = number of perforation block dots / 2400 × 100%
The above-described perforation occurrence probability is assigned to the Y-axis, and the X-axis is assigned to each environment (temperature, humidity) and plate making length.
From the results shown in FIG. 9, when the above-described master 61 is melted and perforated by the heat generated by the heating resistor of the thermal head, the thermal head 91 in this embodiment is used to close the perforation (in the final printed image). It turns out that there is no ink discharge and it falls out white), which is considerably reduced. Moreover, it turns out that the same effect is acquired also in each use environment.
In the master with the conditions of 20% ≦ X _{V2 ≈25} %, 1% ≦ X _V2 −X _{V2R ≈15} %, there is a difference in the perforation state of the thermoplastic resin film, but the perforation _blockage which becomes a problem is conventionally known. It did not occur in any of the thermal heads of the present invention and the thermal head of the present invention.

In the above embodiment, the master 61 that satisfies _{20%> X V2} and _1%> X _{V2 -X V2R} conditions, the perforated closing probability even using the master 61 that satisfy either of the conditions It was confirmed by experiments that it can be reduced compared to the prior art.

A second embodiment is shown based on FIG. In addition, the same part as the said embodiment is shown with the same code | symbol, and unless it was especially required, the description on the structure and function which were already performed is abbreviate | omitted, and only the principal part is demonstrated.
The present embodiment is characterized in that an energization number counter 224 is provided as energization number counting means for counting the number of energizations to the heating resistor 218. The microcomputer 220 functions as a perforation energy adjusting means for adjusting the perforation energy supplied to the heating resistor 218 in accordance with the number of energizations counted by the energization number counter 224.
The microcomputer 220 temporarily stores the energization number counted by the energization number counter 224 in the memory unit, and calculates the energization rate of each heating resistor 218. In the ROM, an energization pulse and a relational data table of energization pulse widths corresponding to perforation energy for forming a perforation having an optimum size corresponding to a change in the energization rate are previously tested (including computer simulation). Is stored in the memory.
The microcomputer 220 selects and sets the energization pulse width corresponding to the calculated energization rate value from the data table.

A third embodiment will be described with reference to FIG.
The present embodiment is characterized in that an ink temperature sensor 225 is provided as ink temperature detection means for detecting the temperature of ink in the printing drum 101.
The ink temperature sensor 225 is disposed in contact with the ink in the ink reservoir 107 in the printing drum 101.
The microcomputer 220 functions as a perforation energy adjusting unit for each ink temperature that adjusts perforation energy supplied to the heating resistor 218 in accordance with the detection value by the ink temperature sensor 225. The temperature of the ink is related to the viscosity and discharge amount of the ink, and as a result, is related to the ink density and the image quality.
In the ROM, a relational data table of the energization pulse width corresponding to the perforation energy for forming the perforation of the optimum size corresponding to the change of the ink temperature and the ink temperature is previously tested (including computer simulation). Is stored in the memory.
Based on the ink temperature information from the ink temperature sensor 225, the microcomputer 220 selects and sets a corresponding energization pulse width from the data table.

1 is a schematic front view of a stencil printing apparatus according to a first embodiment of the present invention. It is an outline sectional view of a master. It is a figure which shows the flow of an image analysis. It is a figure which shows the space | gap part of the master which has a porous resin film. It is a figure which shows the space | gap part of the master which has only a porous fiber membrane. 2A and 2B are diagrams illustrating a thermal head, in which FIG. 1A is a plan view of a main part, and FIG. It is a figure which shows a control system. It is a principal part side view of the thermal head which shows the attachment position of a thermistor. It is a graph which shows perforation blockage incidence. It is a figure which shows the control system in 2nd Embodiment. It is a figure which shows the control system in 3rd Embodiment. It is a figure which shows the generation | occurrence | production state of a piercing blockade.

Explanation of symbols

61 Master as a heat-sensitive stencil master 91 Thermal head 204 Thermoplastic resin film 205 Porous support 206 Porous resin film 210 Aluminum heat sink as heat sink 211 Bonding agent 212 Ceramic substrate 212 as thin film substrate
213 Glaze layer 218 Heat generating resistor 219 Thermistor as thermal head temperature detecting means 220 Microcomputer as thermal head temperature perforating energy adjusting means 220 Microcomputer as heat generation amount correcting means 220 Microcomputer as perforating current adjusting means perforating energy adjusting means 220 Microcomputer as perforating energy adjusting means for each ink temperature 224 Energizing number counter as energizing number counting means 225 Ink temperature sensor as ink temperature detecting means 226 Fan as airflow forming means

Claims (15)

It has a structure in which a thermoplastic resin film and a porous support are bonded together, and a dot-shaped plate-making image corresponding to the image data is formed by position-selective heating with a thermal head equipped with a plurality of minute heating resistors. In the heat-sensitive stencil master,
When a two-dimensional average area porosity of the porous support in a particular area to be transmitted observed from the thermoplastic resin film side was X _V2,
20%> X _V2
A heat-sensitive stencil master satisfying the following conditions: It has a structure in which a thermoplastic resin film and a porous support are bonded together, and a dot-shaped plate-making image corresponding to the image data is formed by position-selective heating with a thermal head equipped with a plurality of minute heating resistors. In the heat-sensitive stencil master,
X _V2 is the two-dimensional average area porosity of the porous support in a specific area that is permeated and observed from the thermoplastic resin film side, and one heating resistor of the porous support in the specific area. When the two-dimensional average area porosity calculated based on the void area below the heating area is _XV2R ,
1%> X _V2 -X _V2R
A heat-sensitive stencil master satisfying the following conditions: In the heat-sensitive stencil master according to claim 1 or 2,
A thermosensitive stencil master, wherein the thermoplastic resin film has a thickness of 1 µm or more. In the heat-sensitive stencil master according to claim 1 or 2,
A heat-sensitive stencil master having at least a porous resin film as the porous support. In the heat-sensitive stencil master according to claim 1 or 2,
A heat-sensitive stencil master characterized in that the porous support comprises at least Japanese paper made of chemical fibers or Japanese paper mixed with the above-mentioned chemical fibers and hemp. A thermal head in which a glaze layer is formed on a thin film substrate bonded to a heat sink, and a heating element is formed on the glaze layer to form a plurality of minute heating resistors. In the stencil printing apparatus, in which the pre-printed thermosensitive stencil master is wound around the outer peripheral surface of the printing drum, and printing is performed by supplying ink from the inside of the printing drum,
6. A stencil printing apparatus, wherein the thickness of the glaze layer in the thermal head is 40 [mu] m or less, and the heat-sensitive stencil master according to any one of claims 1 to 5 is used as the heat-sensitive stencil master. . In the stencil printing apparatus according to claim 6,
A stencil printing apparatus, wherein the bonding agent for bonding the thin film substrate to the heat radiating plate is a gel containing a material having high thermal conductivity. In the stencil printing apparatus according to claim 7,
A stencil printing apparatus, wherein the material having a high thermal conductivity is a thermally conductive filler. In the stencil printing apparatus according to claim 7 or 8,
A stencil printing apparatus, wherein the gel agent has a width in the sub-scanning direction of 3 mm or more. In the stencil printing apparatus according to any one of claims 7 to 9,
The stencil printing apparatus, wherein the gel agent has a thickness of 120 μm or less. In the stencil printing apparatus according to any one of claims 6 to 10,
There is provided a thermal head temperature detecting means for detecting the temperature of the thermal head, and a punching energy adjusting means for each thermal head temperature for adjusting the punching energy supplied to the heating resistor according to the detection value by the thermal head temperature detecting means. A stencil printing apparatus characterized by that. The stencil printing apparatus according to claim 11, wherein
It has heat generation amount correction means for correcting the heat generation amount of the thermal head according to the detection value by the thermal head temperature detection means, and performs heat generation amount correction control at least once during the plate making operation. Stencil printing device. In the stencil printing apparatus according to any one of claims 6 to 10,
The energization number counting means for counting the number of energizations to the heating resistor, and the perforation energy adjustment for each energization rate for adjusting the drilling energy supplied to the heating resistor according to the energization number counted by the energization number counting means A stencil printing apparatus comprising means. In the stencil printing apparatus according to any one of claims 6 to 10,
Ink temperature detection means for detecting the temperature of the ink, and perforation energy adjustment means for each ink temperature for adjusting the perforation energy supplied to the heating resistor in accordance with the value detected by the ink temperature detection means A stencil printing machine. In the stencil printing apparatus according to any one of claims 6 to 14,
A stencil printing apparatus comprising air flow forming means for forming an air flow in the vicinity of the thermal head.

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