JP2915776B2 - Thermal stencil printing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive stencil printing apparatus.

[0002]

2. Description of the Related Art A heat-sensitive stencil master having a perforated pattern corresponding to a print image is wound around an outer peripheral surface of a printing drum.
2. Description of the Related Art A stencil printing apparatus that supplies ink from the inner peripheral side of a printing drum and forms an ink image corresponding to a perforation pattern on printing paper using ink that has oozed through the perforation pattern is well known. In such a stencil printing machine,
Each heating portion arranged in a line in the main scanning direction of the thermal head is energized at a fixed heating operation time interval (hereinafter, sometimes referred to as a “line cycle”), and the electric energy is converted into heat energy. The heat-sensitive stencil master is perforated by generating Joule heat.

By the way, when printing is performed in such a stencil printing machine, and the printed paper is sequentially discharged and stacked on a paper discharge tray, the ink on the surface of the printed paper discharged first is discharged next. This causes a problem of so-called set-off, which is transferred to the back surface of the printed paper and stains the back surface of the printed paper. Therefore, in order to solve such a problem of set-off, for example, Japanese Patent Laid-Open No. 2-67133,
JP-A-4-71847 or JP-A-4-265
As in the technique described in JP-A-759-759, it has been proposed to suppress the amount of ink transfer by independently perforating each perforation in the main scanning direction and the sub-scanning direction orthogonal thereto.

[0004]

However, although the above techniques can solve the problem of set-off, if the resolution in the sub-scanning direction is increased while maintaining the fixed line cycle, the perforation of the heat-sensitive stencil master can be reduced. In the scanning direction, the resolution of the print image in the sub-scanning direction cannot be increased, and the print image quality is not sufficient in recent years when higher print image quality is required.

Accordingly, in order to solve such a problem, the present invention provides a method in which the perforations of the heat-sensitive stencil master are independent of each other in the main scanning direction and the sub-scanning direction, and are independent of the resolution in the set sub-scanning direction. It is an object of the present invention to provide a thermosensitive stencil printing apparatus capable of obtaining an optimum perforated state.

[0006]

In order to achieve the above-mentioned object, the invention according to claim 1 is directed to a thermal head having a large number of heating portions arranged in a line in the main scanning direction. In a state where the thermosensitive stencil master having at least the thermoplastic resin film is pressed by the platen roller, while moving the thermosensitive stencil master by the master transport unit in the sub-scanning direction orthogonal to the main scanning direction, according to the image signal. Heat-generating the heat-generating portion to position-selectively melt-perforate the thermoplastic resin film to obtain a perforation pattern corresponding to the image signal, and wind the heat-sensitive stencil master around the outer peripheral surface of a printing drum; A heat-sensitive stencil that supplies ink from the inner peripheral side of the printing drum and forms an ink image corresponding to the image signal on printing paper with ink oozing through the perforation pattern. An apparatus, comprising: a driving unit, a sub-scanning direction resolution setting unit, a driving control unit, and a heating operation time interval control unit, wherein the dimension of the heating unit in the sub-scanning direction is set to the sub-scanning direction resolution. The feed pitch is set to be equal to or less than the length of the feed pitch corresponding to the highest resolution that can be set by the setting means.

The driving means drives the master conveying means so as to move the heat-sensitive stencil master at a predetermined feed pitch. A specific example of the driving unit is a master feed motor connected to the master conveying unit via a rotation transmission member such as a timing belt, and for example, a stepping motor is used. Further, as a specific example of the master transport unit, a master transport roller pair or the like disposed downstream of the platen roller may be used instead of the platen roller.

The sub-scanning direction resolution setting means is provided for setting the resolution in the sub-scanning direction of an ink image as a print image, and is provided on, for example, an operation panel of a thermosensitive stencil printing apparatus. A sub-scanning direction resolution setting key for manually inputting a desired resolution of the ink image in the sub-scanning direction.

The drive control means controls the drive means based on a signal from the sub-scanning direction resolution setting means so as to change the feed pitch corresponding to the set resolution in the sub-scanning direction.

The heating operation time interval control means, based on a signal from the sub-scanning direction resolution setting means, increases the heating operation time interval of the heating section when the set resolution in the sub-scanning direction is high. Having. Specifically, a computer or a microprocessor can be used as the drive control means and the heat generation operation time interval control means. Here, the “heating operation time interval” refers to a heating operation time interval (Th) when energizing the heating elements of the same heat generating portion of the thermal head, and is also referred to as a line cycle (see FIG. 6).

The minute heating portions arranged in the main scanning direction in the thermal head may be of a so-called rectangular type or a heat concentration type.

The heat-sensitive stencil printing machine according to the first aspect can be configured to include an ink temperature detecting means and an energy adjusting means (the second aspect of the invention).

The ink temperature detecting means detects the ink temperature. As a specific example of the ink temperature detecting means, for example, a thermistor can be used. It is desirable that the ink temperature is detected at a portion close to the printing portion, for example, at an ink supply portion inside the printing drum.

The energy adjusting means adjusts the perforation energy supplied to each heat generating portion of the thermal head to a predetermined energy corresponding to the ink temperature detected by the ink temperature detecting means. As the energy adjusting means, specifically, a computer or a microprocessor can be used.

According to a second aspect of the present invention, there is provided a heat-sensitive stencil printing apparatus further comprising head temperature detecting means for detecting a temperature of the thermal head, and an energy adjusting means for controlling the temperature of the thermal head and the ink detected by the head temperature detecting means. The energy for perforation can be adjusted according to the ink temperature detected by the temperature detecting means (the invention according to claim 3). As a specific example of the head temperature detecting means, for example, a thermistor can be used. It is desirable that the temperature of the thermal head be detected at a surface of the heating portion, for example, a portion close to the surface of the center of the heating element layer surrounded by the lead electrodes. Since it is almost impossible, the temperature of the thermal head main body is detected on the thermal head substrate, which is the circuit substrate on which the thermal head is mounted (see FIG. 4).

In the heat-sensitive stencil printing machine according to the second or third aspect, the adjustment of the drilling energy supplied to the individual heat-generating portions of the thermal head may be performed by changing the width of an energizing pulse to the heat-generating portions of the thermal head. Alternatively, the adjustment may be performed by changing the current value flowing to each heat generating portion or the voltage value applied to the heat generating portion according to the image signal. According to a fourth aspect of the present invention, in the heat-sensitive stencil printing machine according to the first, second or third aspect, the heat-sensitive stencil master is substantially composed of only a thermoplastic resin film. That is, as a heat-sensitive stencil master used in the heat-sensitive stencil printing machine according to claim 1, a thermoplastic resin film on a conventionally known porous flexible support such as Japanese paper. Can be used, and a heat-sensitive stencil master "consisting essentially of a thermoplastic resin film" can also be used. Therefore, the heat-sensitive stencil master has at least a thermoplastic resin film. Here, the thermosensitive stencil master “consisting essentially of a thermoplastic resin film” is not only composed of a thermoplastic resin film but also a thermoplastic resin film containing a trace component such as an antistatic agent. Further, it includes one or more thin film layers such as an overcoat layer formed on both main surfaces of the thermoplastic resin film, that is, at least one of the front surface and the back surface.

[0017]

According to the first aspect of the present invention, when the resolution in the sub-scanning direction is set by the sub-scanning direction resolution setting means, the signal is input to the drive control means, and the drive control means By controlling the driving means to change the feed pitch corresponding to the set resolution in the sub-scanning direction, the heat-sensitive stencil master is moved at the feed pitch corresponding to the set resolution in the sub-scan direction. On the other hand, when the resolution in the sub-scanning direction is set by the sub-scanning direction resolution setting unit, the signal is input to the heating operation time interval control unit,
The heat generation time interval control means controls the heat generation time interval of the heat generating portion of the thermal head so as to lengthen the heat generation time interval when the resolution in the sub-scanning direction is high. The size of the perforation in the sub-scanning direction is controlled to an appropriate size, and the size of the heating section in the sub-scanning direction is set to the length of the feed pitch corresponding to the highest resolution that can be set by the sub-scanning direction resolution setting means. Due to the following, independent perforations are performed without connecting the perforations.

According to the second aspect of the present invention, when the ink temperature is detected by the ink temperature detecting means, and the detected ink temperature is input to the energy adjusting means, the energy adjusting means controls the thermal head. The energy for perforation supplied to each heat generating portion is adjusted to a predetermined energy corresponding to the detected ink temperature, and independent perforation is performed without connecting each perforation.

According to the third aspect of the present invention, when the temperature of the thermal head is detected by the head temperature detecting means, and the detected temperature of the thermal head is input to the energy adjusting means, the energy adjusting means further increases the temperature of the thermal head. ,
The perforation energy is adjusted to a predetermined energy corresponding to the detected temperature of the thermal head and the detected ink temperature, and independent perforation is performed without connecting the perforations.

According to the fourth aspect of the present invention, it is possible to use a heat-sensitive stencil master substantially composed of only a thermoplastic resin film. An image is obtained.

[0021]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a thermosensitive stencil printing apparatus according to an embodiment of the present invention. First, the overall configuration of the thermal stencil printing apparatus and its stencil printing process will be briefly described with reference to FIG.

Reference numeral 50 denotes an apparatus main body cabinet. Reference numeral 80 at the upper part of the apparatus main body cabinet 50
The part indicated by the symbol constitutes a document reading unit, and the lower part 90
The part indicated by is the plate making and feeding part, the part indicated by the reference numeral 100 on the left side is the printing drum part on which the porous printing drum 101 is arranged, and the part indicated by the reference number 70 on the left is the plate discharging part and the plate making part 90 The lower part 110 indicates the paper feeding unit, the lower part 120 below the printing drum 101 indicates the printing pressure unit, and the lower left part 130 of the apparatus main body cabinet 50 indicates the paper discharging unit. I have.

Next, the operation of the thermosensitive stencil printing apparatus will be described below, including its detailed configuration.

First, a document 60 having an image to be printed is placed on a document table (not shown) arranged above the document reading section 80, and a plate making start key (not shown) is pressed.
With the press under the plate making start key, first plate discharging process is performed. That is, in this state, the drum unit 1
The used heat-sensitive stencil master 61b used in the previous printing remains attached to the outer peripheral surface of the print drum 101 of No. 00.

First, the printing drum 101 is rotated in the counterclockwise direction, and the rear end of the used heat-sensitive stencil master 61b on the outer peripheral surface of the printing drum 101 is contacted by the pair of plate-release rollers 71a, 71.
b, the pair of rollers 71a and 71b scoop up the rear end of the used heat-sensitive stencil master 61b with one of the stencil release rollers 71a while rotating.
a, 71b, a plate discharging roller pair 73a, 73 disposed to the left of
b is discharged into the plate discharge box 74 while being conveyed in the arrow Y1 direction by the plate discharge conveyance belt pairs 72a, 72b stretched between the plate discharge separation roller pairs 71a, 71b, and the used heat-sensitive stencil master 61b is printed. The plate 101 is peeled off from the outer peripheral surface, and the plate discharging process is completed. At this time, the printing drum 101 continues to rotate in the counterclockwise direction. The used heat-sensitive stencil master 61b which has been peeled and discharged is thereafter compressed inside the plate discharge box 74 by the compression plate 75.

In parallel with the plate discharging process, the original reading section 80 reads the original. That is, the original 60 placed on an original mounting table (not shown) is separated by a separation roller 81, a pair of front original transport rollers 82 a and 82 b, and a pair of rear original transport rollers 83.
Each of the rotations a and 83b is used for exposure reading while being conveyed in the directions of arrows Y2 to Y3. At this time,
When there are many originals 60, only the lowermost original is conveyed by the action of the separation blade 84. The rear document transport roller 83a is driven to rotate by a document transport roller motor 83A, and the front document transport roller 82a is driven via a timing belt (not shown) stretched between the transport rollers 83a and 82a. The roller 8 is driven to rotate.
2b and 83b are respectively driven and rotated. The image reading of the document 60 is performed while the document is conveyed on the contact glass 85.
The reflected light from the surface of the original 60 illuminated by the fluorescent lamp 86 is reflected by a mirror 87 and passed through a lens 88 to be transmitted to the CC
This is performed by causing the light to enter an image sensor 89 made of D (charge coupled device) or the like. That is, the reading of the document 60 is performed by a known “reduced document reading method”,
The original 60 from which the image has been read is discharged onto the original tray 80A. The electric 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 cabinet 50 and is converted into a digital image signal.

On the other hand, in parallel with this image reading operation,
A plate making and plate feeding process is performed based on the digitalized image information. That is, the heat-sensitive stencil master 61 set at a predetermined portion of the plate making and feeding unit 90 is pulled out of the rolled state and pressed against the thermal head 30 via the heat-sensitive stencil master 61. Platen roller 92 as conveying means and feed roller pair 9
Due to the rotation of 3a and 93b, the sheet is intermittently conveyed to the downstream side of the conveying path. Heat-sensitive stencil master 6 conveyed in this way
On the other hand, a large number of minute heat generating portions arranged in a line in the main scanning direction of the thermal head 30 selectively generate heat in accordance with digital image signals sent from the A / D conversion board, respectively. The thermoplastic resin film of the heat-sensitive stencil master 61 that is in contact with the heat-generating portion is melt-punched. As described above, the image information is written as a perforation pattern by the position-selective fusion perforation of the thermosensitive stencil master 61 according to the image information.

The leading end of the prepressed thermosensitive stencil master 61a on which the image information has been written is sent out toward the outer peripheral side of the printing drum 101 by the pair of plate feeding rollers 94a and 94b, and the traveling direction is lowered by a guide member (not shown). And the print drum 101 in the state of the plate feeding position shown in FIG. 1 hangs down toward the expanded master clamper 102 (shown by a virtual line). At this time, the used heat-sensitive stencil master 61b has already been removed from the printing drum 101 by the plate discharging process.

When the leading end of the prepressed thermosensitive stencil master 61a is clamped at a predetermined timing by the master clamper 102, the printing drum 101 rotates in the direction A (clockwise) in FIG. The heat-sensitive stencil master 61a is gradually wound. The rear end of the prepressed heat-sensitive stencil master 61a is moved to the cutter 95 after the prepress.
Is cut to a certain length.

When the plate-making completed thermosensitive stencil master 61a is wound around the outer peripheral surface of the printing drum 101, the plate making and plate feeding steps are completed, and the printing step is started. First, the paper feed table 51
The uppermost one of the printing papers 62 stacked on the upper side is moved by the feed roller 111 and the separation roller pairs 112a and 112b toward the feed roller pairs 113a and 113b with an arrow Y4.
In the direction, and further feed roller pair 113a,
The print data is sent to the printing pressure unit 120 at a predetermined timing synchronized with the rotation of the print drum 101 by the print 113b. The sent printing paper 62 is printed by the printing drum 101 and the press roller 10.
3, the press roller 103, which has been separated from the outer peripheral surface of the printing drum 101, is moved upward, so that the plate-made heat-sensitive stencil master 61a wound on the outer peripheral surface of the printing drum 101 is moved upward. Is pressed. Thus, the perforated portion of the printing drum 101 and the perforated heat-sensitive stencil master 61
Ink oozes out from the perforation pattern portion (a) (not shown), and the ooze out ink is transferred to the surface of the printing paper 62 to form an ink image as a printing image.

At this time, on the inner peripheral side of the printing drum 101, an ink reservoir 107 formed between the ink roller 105 and the doctor roller 106 from the ink supply pipe 104.
The ink is supplied to the inner surface of the printing drum 101 while rotating in the same direction as the rotation direction of the printing drum 101 and in synchronization with the rotation speed of the printing drum 101. It is supplied to the peripheral side. The ink is a W / O emulsion ink.

The printing paper 62 on which the print image has been formed in the printing pressure section 120 is peeled off from the printing drum 101 by the paper discharge peeling claw 114, and is sucked by the suction fan 118 while being sucked by the suction discharge inlet roller 115 and the suction discharge. Due to the counterclockwise rotation of the conveyance belt 117 stretched over the paper exit roller 116, the conveyance belt 117 is conveyed toward the paper discharge unit 130 as indicated by an arrow Y5, and is sequentially discharged and stacked on the paper discharge table 52. Thus, the so-called test printing is completed.

Next, the number of prints is set with a ten-key (not shown), and when a print start key (not shown) is depressed, the steps of feeding, printing, and discharging are repeated by the set number of prints in the same process as the test printing. And all the steps of the stencil printing are completed.

The heat-sensitive stencil master 61 has a thickness of 40 μm obtained by laminating a 1.6 μm-thick thermoplastic resin film on Japanese paper as a porous support. Next, a configuration for setting the resolution in the sub-scanning direction,
The thermal head 30, the platen roller 92 and their related control structures will be described in detail.

As shown in FIG. 1, an operation panel (not shown) above the apparatus main body cabinet 50 has a sub-scanning direction resolution setting means as a sub-scanning direction resolution setting means for setting the resolution in the sub-scanning direction of the ink image. Key 1
0 is provided. This sub-scanning direction resolution setting key 1
0 has the same function as a fine mode setting key in a copying machine or the like, and manually sets a resolution desired by a user to a desired resolution in order to set a resolution in a sub-scanning direction of an ink image on the printing paper 62. Can be entered and set. In this embodiment, each time the sub-scanning direction resolution setting key 10 is pressed once, the sub-scanning direction resolution is set to 30.
It can be set by switching between two stages of 0 DPI or 400 DPI (dot / inch).

The operation panel near the sub-scanning direction resolution setting key 10 has two LEDs (light emitting diodes) 11 for displaying the setting of the resolution in the sub-scanning direction of 300 DPI and 400 DPI in order from the left in the figure. Are located.

The platen roller 92 is connected to a master feed motor 40 as driving means via a timing belt (not shown). The master feed motor 40 is composed of a stepping motor and is driven to rotate intermittently. Therefore, the heat-sensitive stencil master 61 is
With a predetermined feed pitch via the platen roller 92, the sheet is moved in the sub-scanning direction orthogonal to the main scanning direction.

The thermal head 30 has a resolution of 300 DPI (dots / inch), and a so-called rectangular heating element is used as a minute heating element arranged in the main scanning direction. Next, in order to explain the details of the adjustment of the drilling energy supplied to the individual heat generating portions of the thermal head 30, the detailed configuration of the heat generating portion of the thermal head 30 and its operation will be described first.

In the stencil printing apparatus, the image density of the printed image is determined by the amount of ink oozing from the heat-sensitive stencil master 61. The amount of ink oozing out of the heat-sensitive stencil master 61 is proportional to the opening area of each minute perforation constituting the perforation pattern formed in the heat-sensitive stencil master 61, that is, the size of the perforations. It is proportional to sex. Therefore, when the ink is hard and has a low fluidity, the size of the individual perforations forming the perforation pattern is increased to reduce the amount of bleeding due to the low fluidity of the ink. A print image with good image density can be obtained by making up for the increase in area. Conversely, when the ink is soft and has high fluidity,
By reducing the size of the individual perforations forming the perforation pattern, an increase in the amount of bleeding due to the high fluidity of the ink can be suppressed by reducing the opening area of the perforations to obtain a printed image with good image density. be able to.

In other words, in order to obtain a good printed image irrespective of the fluidity of the ink, the perforation pattern should be formed with perforations of a size suitable for the fluidity of the ink. Since the fluidity of the ink is determined by the temperature of the ink, the energy for perforation corresponding to the temperature of each heat generating portion of the thermal head according to each of the ink temperatures, that is, the size of the perforation of the perforation pattern for obtaining an optimal printed image. Can be determined.

Next, referring to FIG. 3, the relation between the perforating energy (the temperature of each heat generating portion of the thermal head) supplied to each heat generating portion of the thermal head and the size of perforation of the perforation pattern. Will be described. Now, FIG.
Referring to (a-3) and (b-3), these figures show a cross-sectional view of the structure of a minute heat generating portion in the thermal head 30. 1A indicates a heating element made of a thin layer of a high electric resistance material, 1B indicates a lead electrode, and 1C indicates a protective film.

The heating element 1A is a substrate (hatched portion)
Is formed on. When a voltage is applied between the lead electrodes 1B, a current flows through the heating element 1A between the lead electrodes 1B, and the heating element 1A in the energized portion generates heat by Joule heat. In the thermal head, such a minute heating portion is formed as shown in FIG.
(A-3) and (b-3) are arranged at a constant pitch in the direction perpendicular to the paper surface, that is, in the main scanning direction.
The punching pattern is formed by the melt punching while being conveyed in the left and right directions of 3) and (b-3), that is, in the sub-scanning direction.

The size of the heating element 1A of the thermal head 30 is 45 in the main scanning direction S as shown in FIG.
and a size of 48 μm in the sub-scanning direction F is used. The dimension of the heating element 1A of the thermal head 30 in the sub-scanning direction F is equal to or less than the length of a feed pitch of 63.5 μm / line (line) corresponding to 400 DPI, which is the highest resolution that can be set by the sub-scanning direction resolution setting key 10. Is set to

The heating element of the thermal head is of the heat-concentrating type (the central portion of the heating element 1a is formed to have a narrow width, the current density is increased in this portion, and heat is concentrated in this portion). In this case, FIG.
As shown in -5), for example, the total length of the heating element portion in the sub-scanning direction F is 50 μm, the length of the heat generation concentrated portion in the same direction is 10 μm, the entire width of the heating element portion in the main scanning direction S is 50 μm, and the heat generation concentration in the same direction. Part width is 15μ
m.

When energy for drilling is supplied to the heat generating portion in the form of electric energy, the energy is supplied to the heat generating element 1.
A converts the heat energy into heat energy, and the temperature of the heat-sensitive stencil master 61 in contact with the protective film 1C rises. The temperature distribution at this time is represented by a curve Tα shown in FIG.
A mountain-shaped distribution like a curve Tβ shown in (b-2) is obtained.
As can be easily understood, FIG. 3A-2 shows a case where the energy for perforation supplied to the heat generating portion is relatively small, and FIG. 3B-2 shows a case where the energy for perforation is relatively large. Is the case.

The straight line indicated by the symbol D in the figure is the “threshold temperature” at which the thermoplastic resin film of the thermosensitive stencil master 61 is melted and pierced. FIG. 3 (a)
-1) or a small perforation h as shown in FIG.
A large perforation h as shown in 1) is melt perforated. In this way, the size of the perforations as one unit of the perforation pattern formed on the heat-sensitive stencil master 61 can be controlled by the perforation energy supplied to the individual heat generating portions of the thermal head 30. This situation is the same whether the heat-generating portion is rectangular or heat-concentrated. As described above, the size of the perforations in the perforation pattern is determined according to each of the ink temperatures, while the size of the perforations is determined by the energy for perforation.
There is a correspondence between the ink temperature and the perforation energy for obtaining an appropriate printed image, and this correspondence can be experimentally determined. Further, most of the heat generated in the heat generating portion of the thermal head 30 is consumed for melting and perforating the heat-sensitive stencil master 61, but a part of the generated heat is transferred to the thermal head 30 main body to be transferred. 30 Increase the temperature of the body. Thermal head 30
Although the temperature rise of the main body is generally not so large, when the thermal head 30 operates continuously for a long time, a certain temperature rise is inevitable. In such a case, heat generated by the heat storage effect of the main body of the thermal head 30 is added to the heat generated by the perforation energy, so that a perforation larger than actually required may be formed.

Therefore, in consideration of such points, the drilling energy is set to a predetermined energy according to the temperature of the thermal head 30 and the ink temperature so that the drilling pattern of the optimal size is formed. Correct and adjust. Further, as described above, the adjustment of the energy for perforation may be performed by changing the current value flowing to each heat generating portion or the voltage value applied to the heat generating portion according to the image signal, but in this embodiment, This is performed by changing the pulse width of the power supply to the heating element 1A of the thermal head 30.

As the ink temperature detecting means for detecting the ink temperature, a thermistor 42 is used as shown in FIG. 2, and detects the ink temperature in the ink pool 107. As the head temperature detecting means for detecting the temperature of the thermal head 30, a thermistor 35 is used as shown in FIGS. In FIG.
The thermistor 35 is disposed on a thermal head substrate 30S, which is a circuit substrate on which the thermal head 30 is mounted, and detects the temperature of the thermal head 30 main body. Reference numeral 30A denotes a heating element housing portion of the thermal head 30, and reference numeral 30H denotes an aluminum radiator. These thermistors 42 and 35 are connected to the microcomputer 20 described later.

Next, a control configuration for changing the resolution in the sub-scanning direction and a configuration for driving and controlling the thermal head 30, the master feed motor 40, and the original conveying roller motor 83A will be described with reference to FIG.

In the figure, reference numeral 20 denotes a microcomputer. The microcomputer 20 includes a thermal head drive circuit 27, a master feed motor drive circuit 41, and a document drive roller motor drive circuit 83, as described later.
B, a command signal and a data signal are transmitted and received between the sub-scanning direction resolution setting key 10, the thermistor 35, and the thermistor 42 to control the entire system of the thermal stencil printing apparatus. The microcomputer 20 includes a CPU (central processing unit), an I / O (input / output) port, a ROM (read-only storage device), a RAM (read / write storage device), and the like, and is connected to a well-known signal bus. Having a configuration. The microcomputer 20 controls the master feed motor 40 to change the feed pitch corresponding to the set resolution in the sub-scanning direction based on the output signal of the sub-scanning direction resolution setting key 10 as described later. When the resolution in the sub-scanning direction is high based on the output signal of the sub-scanning direction resolution setting key 10, the heating operation time interval (line cycle) of the individual heating portions of the thermal head 30 is extended. Control means,
A second drive control means for controlling the document feed roller motor 83A based on the output signal of the sub-scanning direction resolution setting key 10 so as to change the feed pitch corresponding to the set resolution in the sub-scanning direction, and the thermal head 30 Of the thermal head detected by the thermistor 35 and the temperature of the thermistor 42.
Has various functions of an energy adjusting means for adjusting the energy to a predetermined value according to the ink temperature detected by the control unit.

The ROM of the microcomputer 20 includes:
And set the resolution in the sub-scanning direction in relation data for setting the feeding pitch corresponding, the line period to lengthen the line period of each of the heat generating portion of the thermal head 30 when high set the resolution in the sub-scanning direction Setting data, energy adjustment program, ink temperature and thermal head temperature related data for obtaining a proper print image, and forming perforations of optimal size according to these temperatures Is related to the perforation energy and is experimentally determined and stored in advance.

The outputs of the sub-scanning direction resolution setting key 10, the thermistor 35 and the thermistor 42 are input to the I / O port of the microcomputer 20.

In FIG. 2, reference numeral 25 denotes a decoding circuit, reference numeral 26 denotes a power supply, reference numeral 27 denotes a thermal head driving circuit, reference numeral 41 denotes a master feed motor driving circuit, and reference numeral 83B denotes a motor driving circuit for a document conveying roller.

The decoding circuit 25 has a function of decoding an image signal digitally encoded by the analog / digital (A / D) conversion board into an image data signal. Output.
The decoding circuit 25 is connected to the master feed motor drive circuit 41 via a signal line (not shown).

The master feed motor drive circuit 41 comprises: 1-2
The output of the 1-2 phase excitation circuit that generates the phase excitation pulse is supplied to the master feed motor 40. The master feed motor drive circuit 41 is connected to the master feed motor 40 and drives the master feed motor 40.

The thermal head driving circuit 27 receives the image data signal output from the decoding circuit 25, the signal indicating one sub-scanning, and the command and data signal for setting the energizing pulse width and line cycle output from the microcomputer 20. It mainly comprises a drive circuit for receiving and outputting a thermal head drive signal. Also, the thermal head 30
A shift register for sequentially shifting image data signals for the main scan, a latch circuit for latching the output of each stage of the shift register, and a thermal head 3 corresponding to a black pixel
An AND circuit for driving only the heat-generating portion of 0, a transistor for driving the heat-generating portion of the thermal head 30, a diode for preventing reverse current, and the like are provided. The power supply 26 is connected to the thermal head drive circuit 27 and, through the thermal head drive circuit 27, responds to the energy for perforating the heat-sensitive stencil master 61 to melt and perforate the individual heat generating portions of the thermal head 30. Provides electrical energy.

Document drive roller motor drive circuit 83B
Has a configuration similar to that of the master feed motor drive circuit 41, and supplies the output of the 1-2-phase excitation circuit that generates the 1-2-phase excitation pulse to the motor 83A for the document conveying roller.

Next, with reference to FIGS. 2, 5, 6, and 7, an example of changing the resolution in the sub-scanning direction and an operation process thereof will be described.

First, before pressing the above-described plate making start key to execute the plate making process, the sub-scanning direction resolution setting key 1 is set.
Pressing 0 sets the resolution in the sub-scanning direction desired as a print image. When the resolution setting signal in the sub-scanning direction is output to the microcomputer 20, the microcomputer 20 sends a signal for driving and controlling the master feed motor 40 at a predetermined feed pitch corresponding to the resolution in the sub-scanning direction. While sending it to the drive circuit 41,
A signal for controlling the driving of the original conveying roller motor 83A at a predetermined feed pitch corresponding to the resolution in the sub-scanning direction is sent to the original conveying roller motor driving circuit 83B. At the same time, the microcomputer 20 sets an appropriate line cycle according to the resolution in the sub-scanning direction, that is, sets a long line cycle when the resolution in the sub-scanning direction is high, and sends the signal to the thermal head drive circuit 27. . And
The master feed motor 40 is driven via a master feed motor drive circuit 41 based on a signal of a predetermined feed pitch setting corresponding to the sub-scanning direction resolution set by the microcomputer 20, and furthermore, the platen roller 92 is driven by the master feed motor 40. Is driven to rotate, and the heat-sensitive stencil master 61 is conveyed at a predetermined feed pitch and speed.

Further, based on a signal of a predetermined feed pitch setting corresponding to the resolution in the sub-scanning direction set by the microcomputer 20, the motor 83A for the original conveying roller is driven via the motor driving circuit 83B for the original conveying roller, and Further, the front and rear document transport roller pairs 82a, 82b, 83a, 83b are rotated by the document transport roller motor 83A, and the document 60 is transported at a predetermined feed pitch and speed.

At the same time, when a resolution setting signal in the sub-scanning direction is output to the microcomputer 20, the microcomputer 20 determines the temperature of the thermal head 30 detected by the thermistor 35 and the ink temperature detected by the thermistor 42. In accordance with, set an appropriate energizing pulse width such that a drilling pattern of drilling of the optimal size is formed,
The signal is sent to the thermal head drive circuit 27. In the thermal head drive circuit 27, a thermal head drive signal is generated by receiving power supply from the power supply 26 based on the signal of the line cycle and the energizing pulse width, and is output to each heat generating portion of the thermal head 30, and the black pixel The heat-generating portion corresponding to (1) generates Joule heat, and the heat-sensitive stencil master 61 is melt-punched.

Next, the resolution in the sub-scanning direction is set to 300 DPI.
And the relationship between the line cycle and the perforated state of the heat-sensitive stencil master 61 when changing to 400 DPI.

FIGS. 7A and 7B show a resolution of 300 DP.
I in the sub-scanning direction using the thermal head 30 having
Is set to 300 DPI, that is, the feed pitch Pf of the heat-sensitive stencil master 61 is set to 84.7 μm /
The perforated state of the heat-sensitive stencil master 61 when the line cycle is set to 2 msec / line (FIG. 7A) and 5 msec / line (FIG. 7B) is shown. In both cases, the thermal head 3
The drilling energy supplied to each of the 0 heating elements, that is, the energization pulse width as electric energy is the same.

As shown in FIGS. 7A and 7B, the perforation state changes by changing the line cycle. In other words, the line period shorter (fast as shown in FIG. 7 (a)
By Ku) for, drilling h in the sub-scanning direction F in heat-sensitive stencil master 61 is increased, conversely, and FIG. 7 (b)
By making the line cycle longer (slower) as shown in (1) , the perforation h in the sub-scanning direction F in the heat-sensitive stencil master 61 becomes smaller.

FIGS. 8A and 8B show a resolution of 300 DP.
I in the sub-scanning direction using the thermal head 30 having
5 shows the perforated state of the heat-sensitive stencil master 61 when the resolution of is set to 300 DPI and 400 DPI, respectively. FIG. 8A shows the feed pitch Pf of the thermosensitive stencil master 61 in the perforated state of the thermosensitive stencil master 61 under the same conditions as in FIG. 7A, that is, when the resolution in the sub-scanning direction F is set to 300 DPI. To 84.7 μm / li
Ne represents the perforated state of the thermosensitive stencil master 61 when the line cycle is set to 2 msec / line. FIG. 8B shows that the resolution in the sub-scanning direction F is 400 DP.
When it is set to I, that is, when the feed pitch Pf of the heat-sensitive stencil master 61 is 63.5 μm / line and the line cycle is set to 5 msec / line, the perforated state of the heat-sensitive stencil master 61 is shown. Note that in the same manner as described above, in both states, the widths of the energizing pulses supplied to the individual heating portions of the thermal head 30 are the same.

As shown in FIGS. 8A and 8B, the perforation state is changed by changing the line cycle. FIG.
By shortening (fastening) the line cycle as shown in (a), the perforation h in the sub-scanning direction F in the heat-sensitive stencil master 61 becomes large, and conversely, as shown in FIG. By making the cycle longer (slower) , the perforation h in the sub-scanning direction F in the heat-sensitive stencil master 61 becomes smaller. As shown in FIG. 8B, the sub-scanning direction F
In the case where the resolution is increased from 300 DPI to 400 DPI, independent perforations corresponding to the resolution in the sub-scanning direction F can be obtained without connecting the perforations h in the main scanning direction S and the sub-scanning direction F. An optimal image quality corresponding to the resolution in the direction F can be obtained.

[0068] Here, as shown in FIG. 8 (b), when the line period to increase the resolution in the sub-scanning direction F to 400DPI long as 5 msec / line, the 8
The resolution shown in (a) is 300 DPI, and the line cycle is 2 ms.
As in the case of ec / line, the perforations are formed at appropriate intervals in the sub-scanning direction F, and an ink image without unevenness due to ink bleeding on printing paper can be formed. On the other hand, when the resolution in the sub-scanning direction F is kept at 300 DPI and only the line cycle is increased to 5 msec / line as shown in FIG.
The resolution shown in (a) is 300 DPI, and the line cycle is 2 ms.
The perforations may be too far apart in the sub-scanning direction F than in the case of ec / line, causing insufficient ink bleeding on the printing paper to generate white stripes.

The results of these perforations can be explained with reference to FIGS. 2 and 6 for the following reasons. That the line cycle Ru to <br/> long is that the rotational speed of the platen roller 92 for transporting the heat-sensitive stencil master 61, i.e. that slows the rotational speed of the master feed motor 40. FIG.
In the case of (b), the feed pitch Pf = 84.7 μm / l
5ms to transport heat sensitive stencil master 61 for ine
ec / line is required, and the feed speed is about 16.9 μm / msec. Similarly, FIG.
, The feed pitch Pf = 63.5 μm / line
5msec / to transport the heat-sensitive stencil master 61
line, and the feed rate is about 1
2.7 μm / msec. Further, under the setting conditions of FIGS. 7A and 8A, the feed pitch Pf = 8
It takes 2 msec / line to transport the 4.7 mm / line heat-sensitive stencil master 61, and the feed speed is about 42.4 m / msec.

As described above, when the line cycle is lengthened and the feed speed of the heat-sensitive stencil master 61 is reduced, FIG.
As shown in (a) and (b), the energizing pulse width tp
Are the same value, the heat-sensitive stencil master 61 moves the thermal head 3 within the time corresponding to the energizing pulse width tp.
Since the portion that is conveyed and moved in the sub-scanning direction F by contacting the heat-generating portion 0 becomes shorter, the diameter of the perforation h in the sub-scanning direction F becomes smaller. In general, the longer the line cycle Th, the smaller the amount of heat stored in the heat-generating portion of the thermal head due to heat dissipation and the like. Therefore, the perforation h in the sub-scanning direction F is further reduced in addition to the above operation. The size of the perforations h in the main scanning direction S becomes slightly larger when the line cycle Th is made faster, but is not so affected as shown in FIGS.
In the perforated state in, this is neglected to clarify the features of the present embodiment.

As described above, in consideration of the above-mentioned items, when only the line cycle is changed based on the setting of the resolution in the sub-scanning direction, the results of the perforated diameters formed on the thermosensitive stencil master are listed. It looks like this:

Resolution in the sub-scanning direction 300 DPI 400 DPI Line period (msec / line) 25 Drilling diameter (μm) in the sub-scanning direction 68.1 55.3 As the plate making conditions, the thermal head has a resolution of 300 DPI and a heating element. The size used is 45 μm in the main scanning direction × 48 μm in the sub-scanning direction, the temperature of the thermal head is 20 ° C., and the energizing pulse width is 400 μsec (0.4 μm).
msec).

In the case of a line cycle of 2 msec / line and a resolution of 300 DPI in the sub-scanning direction, that is, FIG.
During this 2 msec, the heat-sensitive stencil master was 84.7 μm
It moves, but during tp = 0.4 msec, (84.
7 μm / line) ÷ (2 msec / line) × 0.
Move by 4 msecｓｅ17 μm. On the other hand, line cycle 5m
8B, the thermosensitive stencil master moves 63.5 μm during this 5 msec, but tp = 0.4 m
During (sec), (63.5 μm / line) ÷ (5 m
(sec / line) × 0.4 msec ≒ 5 μm. This joined by shrinkage action of the action and the thermoplastic resin film of heat accumulated in the heat generating portion of the thermal head, are I Do to 68.1Myuemu, perforation diameter, such as 55.3μm above embodiments.

As described above, the perforations h are not connected in the main scanning direction S and the sub-scanning direction F, so that an optimal perforation corresponding to the resolution in the sub-scanning direction can be obtained, and the print image quality is also optimal. Things were obtained.

The dimension in the sub-scanning direction of the heating element of the heat generating portion of the thermal head is set to a size within 80% of the length of the feed pitch corresponding to the highest resolution that can be set by the sub-scanning direction resolution setting means. It is desirable to do. That is, in the case of this embodiment, the sub-scanning direction resolution setting key 1
The maximum resolution in the sub-scanning direction that can be set at 0 is 400 DP
I, and the feed pitch is 63.5 μm / line, so the dimension of the heating element in the sub-scanning direction is 5
1 μm or less is desirable. Thereby, even when the resolution in the sub-scanning direction is increased, it is more ensured that the perforations are made independently without being connected in the sub-scanning direction.

The dimension of the heating element of the thermal head in the sub-scanning direction in the sub-scanning direction is set to a size in the range of 40% or more of the length of the feed pitch corresponding to the highest resolution that can be set by the sub-scanning direction resolution setting means. It is desirable to do. That is, in the case of this embodiment, the sub-scanning direction resolution setting key 1
The maximum resolution in the sub-scanning direction that can be set at 0 is 400 DP
I, and the feed pitch is 63.5 μm / line, so the dimension of the heating element in the sub-scanning direction is 2
5 μm or more is desirable. In this way, by setting the size in the range of 40% or more of the length of the feed pitch, it is possible to reliably perform perforation. This is because if the heating element is too small, the life of the heating element is shortened due to repetition of heat generation.

In many cases of experiments repeated many times, the line period was set to 3 msec by using a thermal head having a resolution of 400 DPI and a heating section having a size of 30 μm in the main scanning direction × 40 μm in the sub-scanning direction. / L
In an experiment performed with the temperature of the thermal head constant, the temperature of the thermal head did not change. In such a case, the energizing pulse width was set based on only the ink temperature. .

As described above, as an example of setting the energy for perforation based on only the ink temperature, the energizing pulse width and the ink viscosity (flow value: JIS) when the ink temperature is 10 ° C., 20 ° C., and 30 ° C. -K5701), the diameter of the perforation formed by melting and perforation, and the print image density measured as the reflection density by a Macbeth densitometer are listed below. At this time, a thermosensitive stencil master having a thickness of 40 μm obtained by laminating a thermoplastic resin film having a thickness of 2 μm on Japanese paper as a porous support was used.

Ink temperature 10 degrees C 20 degrees C 30 degrees C Energizing pulse width (μS) 600 530 460 Ink viscosity (mm) 27.8 29.5 32.2 Perforation diameter (μm) 55 52 48 Print image density 0.95 0.95 0.95 Thus, a good printed image having a constant image density could be obtained regardless of the change in the ink temperature.

As described above, according to this embodiment, a novel thermosensitive stencil printing apparatus can be provided. Since this apparatus is configured as described above, a good printed image can always be realized irrespective of a change in ink fluidity due to a change in ink temperature. In this embodiment, according to the ink temperature or the ink temperature and the thermal head temperature, the size of the perforation of the perforation pattern formed on the thermosensitive stencil master is adjusted by the perforation energy set on the thermal head. Unlike the method of mechanically adjusting the pressing force between the heat-sensitive stencil master and the printing paper in the printing pressure section, and the method of adjusting the printing speed, there is no need to change the mechanical conditions or sequence conditions of the device, and it is easy. In addition, the density of the printed image can be reliably stabilized.

If the temperature inside the thermosensitive stencil printing machine is stable, the ink temperature is substantially equal to the inside temperature of the machine. Therefore, instead of detecting the ink temperature, the inside temperature of the machine is detected and the perforation pattern is determined. Even if the size of the perforation is adjusted, the same effect as described above can be obtained.However, in general, the temperature in the printing apparatus changes according to the use condition, and there is a difference between the ink temperature and the temperature in the apparatus. It is difficult to achieve the concentration stabilization as in the embodiment.

Further, the heat-sensitive stencil printing apparatus can use a heat-sensitive stencil master substantially composed of only a thermoplastic resin film.
When the perforation was performed under the same conditions as in the above-described embodiment, independent perforation was performed without connecting the perforations as in the above-described embodiment, and the desired perforation corresponding to the resolution in the sub-scanning direction was performed. Print image quality, and
The stain on the printing paper due to set-off was minimized.

Further, according to the above-described embodiment, there is an advantage that the above-described configuration can be used properly as follows. That is, when it is important to shorten the plate making time, if the resolution in the sub-scanning direction is set to a low resolution, the line cycle is shortened , so that the plate making time can be reduced. Conversely, when printing image quality is important, setting the resolution in the sub-scanning direction to a high resolution will lengthen the line cycle. Although the time is long, a high-quality print image can be obtained.

The master conveying means is not limited to a system in which the platen roller 92 is driven by the master feed motor 40 as in the above embodiment, but may be a driving system as shown in FIG. The plate making and feeding unit shown in FIG. 9 is different from the plate making and feeding unit 90 in FIG. 1 in that a pair of master transport rollers 91a and 91b as master transport means are disposed downstream of a platen roller 92. A master feed motor 91A as a driving means is connected to a pair of master transport rollers 91a and 91a via a timing belt (not shown).
The only difference is that the platen roller 92 is driven to rotate by eliminating the master feed motor 40 connected to the platen roller 92 via a timing belt (not shown). According to the driving method shown in the figure, the master transport rollers 91a and 91b transport and move the heat-sensitive stencil master 61 by rotating the master feed motor 91A, and the platen roller 92 is driven while pressing the heat-sensitive stencil master 61. Rotated.

The resolution in the sub-scanning direction is, for example, stepwise switched between 300 DPI and 400 DPI as in this embodiment, or from 300 DPI to 400 DPI.
May be changed continuously. As means for changing the feed pitch corresponding to the resolution in the sub-scanning direction, for example, an apparatus described in Japanese Utility Model Laid-Open No. 59-161765, that is, page 4, line 9 to page 5, of the same specification is used. A mechanism similar to that described in line 10 may be used.

The feed operation for transporting the heat-sensitive stencil master in the sub-scanning direction is not limited to the intermittent movement at a predetermined feed pitch as in the above embodiment, but may be a continuous feed. Needless to say.

In the above-described embodiment, when reading the original, the original is read while the original 60 is being conveyed by rotating the original conveying roller pair by the motor 83A for the original conveying roller, and the original 60 is conveyed. The original 60 may be mounted and fixed on a contact glass, and the original may be read while moving an optical system including a fluorescent lamp and a mirror by a drive motor. In this case, the drive motor may be controlled to change the moving speed of the optical system to a predetermined feed pitch corresponding to the resolution in the sub-scanning direction.

The place where the thermistor 35 is disposed is not limited to the position on the thermal head substrate 30S, but the aluminum radiator 30H.
May be provided inside.

The embodiment of the present invention is not limited to the above-described embodiment. In the embodiment shown in FIGS. 1 to 8, the thermistor 35 and the thermistor 42 are deleted from the configuration shown in FIGS. A heat-sensitive stencil printing apparatus having a configuration in which the function of the energy adjusting means (the function of setting the energizing pulse width) from the microcomputer 20 is deleted may be used. That is, in a state where at least a heat-sensitive stencil master having a thermoplastic resin film is pressed by a platen roller against a thermal head having a large number of heating portions arranged in a line in the main scanning direction, the main scanning is performed. While moving the heat-sensitive stencil master by the master transport means in the sub-scanning direction orthogonal to the direction, the heat-generating portion is heated according to an image signal to melt-perforate the thermoplastic resin film in a position-selective manner, thereby forming the image. A perforation pattern corresponding to the signal is obtained, the heat-sensitive stencil master is wound around the outer peripheral surface of the printing drum, ink is supplied from the inner peripheral side of the printing drum, and the ink exuded through the perforation pattern is used as the ink. A heat-sensitive stencil printing apparatus for forming an ink image according to an image signal on printing paper, wherein said heat-sensitive stencil master is moved at a predetermined feed pitch. Driving means for driving the master transport means, sub-scanning direction resolution setting means for setting the resolution in the sub-scanning direction, and a resolution in the sub-scanning direction set based on a signal from the sub-scanning direction resolution setting means. A drive control unit that controls the drive unit to change the feed pitch to a feed pitch corresponding to the sub-scanning direction resolution setting unit, based on a signal from the sub-scanning direction resolution setting unit, when the resolution in the sub-scanning direction is high, and a heating operation time interval control means for extending the operating time interval, the sub-scanning direction dimension of the heating unit, the length of the feed pitch corresponding to the highest resolution that can be set in the sub-scanning direction resolution setting means The following may be adopted (the invention according to claim 1). The embodiment to which the present invention is applied will be described with reference to, for example, FIG. 2. The thermal head driving circuit 27 is shown in FIG. 1 of Japanese Utility Model Laid-Open Publication No. 2-65560 and the specification, page 6, line 2 to page 9. It may have a configuration and a function similar to those described in the first row.

That is, the thermal head driving circuit outputs the image data signal output from the decoding circuit 25,
A drive circuit for receiving a signal indicating the sub-scanning, a line cycle setting command and a data signal output from the microcomputer 20, and outputting a thermal head driving signal; and a driving circuit provided in the driving circuit for improving the resolution in the sub-scanning direction. It mainly comprises a plurality of pulse width generating circuits for generating a thermal head drive signal having a predetermined energizing pulse width, and a selector for switching the output of these pulse width generating circuits.

Further, the embodiment of the present invention is not limited to the above-described embodiment, and a thermosensitive stencil printing machine having a configuration in which the thermistor 42 is omitted from the configuration of FIG. 2 in the embodiment shown in FIGS. It may be. That is, in a state where at least a heat-sensitive stencil master having a thermoplastic resin film is pressed by a platen roller against a thermal head having a large number of heating portions arranged in a line in the main scanning direction, the main scanning is performed. While moving the heat-sensitive stencil master by the master transport means in the sub-scanning direction orthogonal to the direction, the heat-generating portion is heated according to an image signal to melt-perforate the thermoplastic resin film in a position-selective manner, thereby forming the image. A perforation pattern corresponding to the signal is obtained, the heat-sensitive stencil master is wound around the outer peripheral surface of the printing drum, ink is supplied from the inner peripheral side of the printing drum, and the ink exuded through the perforation pattern is used as the ink. A heat-sensitive stencil printing apparatus for forming an ink image according to an image signal on printing paper, wherein said heat-sensitive stencil master is moved at a predetermined feed pitch. Driving means for driving the master transport means, sub-scanning direction resolution setting means for setting the resolution in the sub-scanning direction, and a resolution in the sub-scanning direction set based on a signal from the sub-scanning direction resolution setting means. A drive control unit that controls the drive unit to change the feed pitch to a feed pitch corresponding to the sub-scanning direction resolution setting unit, based on a signal from the sub-scanning direction resolution setting unit, when the resolution in the sub-scanning direction is high, a heating operation time interval control means for extending the operating time interval, and the head temperature detecting means for detecting the temperature of the thermal head, the drilling energy supplied to each heat generating portion of the thermal head, detected by the head temperature detecting means Energy adjusting means for adjusting to a predetermined drilling energy according to the temperature of the thermal head, Serial scanning direction dimension may be obtained by the following length of the feed pitch corresponding to the highest resolution that can be set in the sub-scanning direction resolution setting means.

[0092]

As described above, according to the first aspect of the present invention, when the resolution in the sub-scanning direction set by the sub-scanning direction resolution setting means is high, the heating operation time interval By controlling the heat-generating operation time interval to be long by the control means, the size of the perforations in the sub-scanning direction of the heat-sensitive stencil master is controlled to an appropriate size, and the sub-scanning direction in the heat-generating portion is controlled. Is set to be equal to or less than the length of the feed pitch corresponding to the highest resolution that can be set by the sub-scanning direction resolution setting means, so that independent perforations are performed without connecting the perforations. It is possible to obtain a print image quality commensurate with the resolution and to minimize the stain on the printing paper due to set-off.

According to the second aspect of the present invention, when the ink temperature is detected by the ink temperature detecting means, and the detected ink temperature is input to the energy adjusting means, the energy adjusting means controls the operation of the thermal head. The perforation energy supplied to each heat generating portion is adjusted to a predetermined energy according to the detected ink temperature, and independent perforation is performed without connecting each perforation, so that it is adapted to the resolution in the sub-scanning direction. Appropriate print image quality can be obtained, and soiling of the printing paper due to set-off can be prevented.

According to the third aspect of the present invention, the temperature of the thermal head is further detected by the head temperature detecting means, and when the detected temperature of the thermal head is input to the energy adjusting means, the energy adjusting means detects the temperature of the thermal head. ,
The perforation energy is adjusted to a predetermined energy according to the detected temperature of the thermal head and the detected ink temperature, and independent perforation is performed without connecting each perforation, so it is adapted to the resolution in the sub-scanning direction. In addition, it is possible to obtain the appropriate print image quality, and to prevent the printing paper from being stained by set-off.

According to the fourth aspect of the present invention, since a heat-sensitive stencil master substantially composed of only a thermoplastic resin film is used, in addition to the above-described effects, a good printed image without a so-called fibrous grain is obtained. be able to.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a thermosensitive stencil printing apparatus to which an embodiment of the present invention is applied.

FIG. 2 is a block diagram illustrating a control configuration of the thermosensitive stencil printing apparatus.

FIG. 3 is a diagram for explaining a configuration of a thermal head and a punching action.

FIG. 4 is a side view showing the location of a thermistor for detecting the temperature of the thermal head.

FIG. 5 is a flowchart illustrating a control operation when a resolution in the sub-scanning direction is set.

FIGS. 6A and 6B are diagrams for explaining a relationship between a line cycle as a heating operation time interval and an energizing pulse width.

FIG. 7A shows a resolution in the sub-scanning direction of 300 DP.
I, the line cycle is 2 msec / line, and FIG. 7B shows a resolution in the sub-scanning direction of 300 DPI and
It is a top view explaining the perforation state of the thermosensitive stencil master when a line period is set to 5 msec / line.

FIG. 8A shows a resolution in the sub-scanning direction of 300 DP.
I, and the line cycle is 2 msec / line, FIG. 8B shows a resolution in the sub-scanning direction of 400 DPI, and
It is a top view explaining the perforation state of the thermosensitive stencil master when a line period is set to 5 msec / line.

FIG. 9 is a configuration diagram of a plate making and feeding unit showing a modified example of the master transport unit.

[Explanation of symbols]

1A Heating Element in Heating Section of Thermal Head 10 Subscanning Direction Resolution Setting Key as Subscanning Direction Resolution Setting Means 20 Microcomputer as Drive Control Means, Heating Operation Time Interval Control Means, and Energy Adjusting Means 30 Thermal Head 35 Head Temperature Detection Thermistor 40 as a means 40 Master feed motor as a driving means 42 Thermistor as an ink temperature detecting means 61 Thermosensitive stencil master 92 Platen roller 101 as a master transport means 101 Printing drum 107 Ink pool F Sub scanning direction S Main scanning direction

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-265759 (JP, A) JP-A-4-334485 (JP, A) JP-A-2-51464 (JP, U) (58) Field (Int.Cl. ⁶ , DB name) B41C 1/00-1/18 B41L 13/04 B41J 2/32-2/37

Claims (4)

(57) [Claims] 1. A heat-sensitive stencil master having at least a thermoplastic resin film is pressed by a platen roller against a thermal head having a large number of heating portions arranged in a line in the main scanning direction. While moving the heat-sensitive stencil master by the master conveying means in the sub-scanning direction orthogonal to the main scanning direction, the heat-generating portion is heated according to an image signal to selectively melt-punch the thermoplastic resin film. To obtain a perforation pattern corresponding to the image signal,
This heat-sensitive stencil master is wound around the outer peripheral surface of the printing drum,
A heat-sensitive stencil printing machine that supplies ink from the inner peripheral side of the printing drum and forms an ink image corresponding to the image signal on printing paper by ink oozed through the perforation pattern; A driving means for driving the master transport means so as to move at a predetermined feed pitch, a sub-scanning direction resolution setting means for setting the resolution in the sub-scanning direction, and a signal from the sub-scanning direction resolution setting means. Drive control means for controlling the drive means to change the feed pitch corresponding to the set resolution in the sub-scanning direction; and resolution set in the sub-scanning direction based on a signal from the sub-scanning direction resolution setting means. when high, and a heating operation time interval control means for lengthening the heating operation time interval of the heating unit, the sub-scanning direction in the heat generating unit Dimensions, thermal stencil printing apparatus being characterized in that the following length of the feed pitch corresponding to the highest resolution that can be set in the sub-scanning direction resolution setting means. 2. A thermal stencil printing machine according to claim 1, wherein said ink temperature detecting means detects an ink temperature, and said perforating energy supplied to each heat generating portion of said thermal head is detected by said ink temperature detecting means. And an energy adjusting means for adjusting the energy to a predetermined energy corresponding to the ink temperature. 3. The heat-sensitive stencil printing apparatus according to claim 2, further comprising head temperature detecting means for detecting a temperature of the thermal head, wherein said energy adjusting means has a function of detecting the temperature of said thermal head. A heat-sensitive stencil printing machine wherein the energy for perforation is adjusted according to the temperature and the ink temperature detected by said ink temperature detecting means. 4. The heat-sensitive stencil printing apparatus according to claim 1, wherein the heat-sensitive stencil master is substantially composed of only a thermoplastic resin film.