JPH08132723A - Heat-sensitive stencil printing device - Google Patents

Abstract

PURPOSE: To provide a heat-sensitive stencil printing device which can obtain an optimum and favorable printed image and eliminate an offset phenomenon characteristic of the heat-sensitive stencil printing machine without adjusting pressure-contacting force between a heat-sensitive stencil master and printing form, whatever kind of ink may be used in a printing drum. CONSTITUTION: In a heat-sensitive stencil printing device forming an ink image on a printing form, it possesses a hole element sensor group 20 constituting an ink kind detecting device within a printing drum detecting a kind of an ink within the printing drum and a microprocessor 5 as a boring energy- adjusting device adjusting the boring energy to be applied to individual heating unit part of a magnet and thermal head 91 in accordance with the kinds of the ink within the printing drum detected by the ink kind detecting device within the printing drum.

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, and more particularly to a heat-sensitive stencil printing apparatus capable of detecting the type of ink in a printing drum and obtaining an optimum and good printed image.

[0002]

2. Description of the Related Art A heat-sensitive stencil master on which a perforation pattern corresponding to a printed image is formed is wound around an outer peripheral surface of a printing drum,
A well-known stencil printing machine supplies ink from the inner peripheral side of a printing drum and forms an ink image according to the perforation pattern on a printing paper by the ink bleeding through the perforation pattern.

In such a stencil printing machine, in order to obtain an optimum printed image even when the kind of ink in the printing drum is changed, for example, Japanese Patent Laid-Open No. 2-151473,
JP-A-6-155881 or JP-A-6-1990
As disclosed in Japanese Patent No. 28, etc., various techniques for mechanically adjusting the pressure contact force between the heat-sensitive stencil master and the printing paper have been proposed, and these techniques can be used.

Further, as a technique for detecting the type of ink in the print drum, for example, those disclosed in JP-A-64-18682 and JP-A-64-18683 are disclosed in the print drum. As a technique for detecting the temperature of the ink and the temperature of the thermal head, for example, the techniques disclosed in Japanese Patent Application No. 5-109341 proposed by the same applicant can be used.

[0005]

However, the thermal head is brought into contact with at least a heat-sensitive stencil master having a thermoplastic resin film, and a minute heating element portion of the thermal head is caused to generate heat in accordance with an image signal. A thermoplastic resin film is melted and perforated in a position-selective manner to obtain a perforation pattern according to the image signal, and this heat-sensitive stencil master is wound around the outer peripheral surface of the printing drum, and ink is supplied from the inner peripheral side of the printing drum. Then, in a heat-sensitive stencil printing apparatus that forms an ink image corresponding to the image signal on a printing paper by the ink bleeding through the perforation pattern, the same heat-sensitive stencil printing is performed for different types of ink in the printing drum. When printing with the device, if the printing is not performed by taking into consideration the fluidity (viscosity) of the ink based on the difference in the type of ink, the heat-sensitive holes The printed image of the printing apparatus, it is impossible to get what optimal good. That is, as is well known, many printing inks include pigments, resins, solvents,
It is an emulsion ink in which a composition such as a surfactant and water is mixed in a predetermined ratio, and has a non-Newtonian pseudoplastic property even in a viscous fluid. Due to the difference in the blending components of the above composition, the difference in the blending ratio, and the difference in the type of pigment and the particle diameter for each color of the ink,
The fluidity of each ink is different, and each ink type has a unique fluidity value (or viscosity) under a specific ink temperature. The fluidity of the ink greatly differs among the types of ink, especially due to the difference in color. Therefore, according to each of the above-mentioned conventional techniques, in order to perform optimum and good printing in consideration of the fluidity (viscosity) of ink based on the difference in ink type, the pressure contact force is mechanically delicately adjusted. Is not always easy, so it is never desirable.

Therefore, in order to solve such a problem, the present invention is suitable for any type of ink in the printing drum without adjusting the pressure contact force between the heat-sensitive stencil master and the printing paper. An object of the present invention is to provide a heat-sensitive stencil printing apparatus which can obtain a good printed image and can eliminate the set-off phenomenon peculiar to a stencil printing machine.

[0007]

In the heat-sensitive stencil printing apparatus of the present invention, a thermal head is brought into contact with a heat-sensitive stencil master having at least a thermoplastic resin film, and a minute heating element portion of the thermal head is set in accordance with an image signal. Heat is generated to melt and punch the thermoplastic resin film in a position-selective manner to obtain a perforation pattern according to the image signal. Is a heat-sensitive stencil printing apparatus for forming an ink image corresponding to an image signal on a printing paper by ink bleeding through a perforation pattern, the ink type detecting means in a printing drum, and a perforating energy adjusting means. (The invention according to claim 1).

The ink type detecting means in the printing drum automatically detects and identifies the type of ink in the printing drum regardless of whether the user or the like knows the type of ink in the printing drum in advance. Is provided for
For example, as described in JP-A-64-18682, a sensor including a small magnet and a Hall element sensor is used.

The perforation energy adjusting means adjusts the perforation energy supplied to each heating element of the thermal head to a predetermined energy according to the ink type in the printing drum detected by the ink type detecting means in the printing drum. . As the drilling energy adjusting means, specifically, a microcomputer, a microprocessor or the like can be used.

Further, in the heat-sensitive stencil printing apparatus according to the present invention, a thermal head temperature detecting means for detecting the temperature of the thermal head is provided, and the perforation energy adjusting means detects the thermal head temperature detecting means. The perforation energy can be adjusted according to the temperature and the type of ink in the printing drum detected by the type of ink in the printing drum (the invention according to claim 2).

A specific example of the thermal head temperature detecting means is a thermistor. It is desirable that the temperature detection point of the thermal head is a surface portion of the heating element portion, for example, a portion near the central surface portion of the heating element portion surrounded by the lead electrodes. Since the temperature detection 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).

Further, in the heat-sensitive stencil printing apparatus according to the first aspect, the ink temperature detecting means for detecting the temperature of the ink in the printing drum is provided, and the perforation energy adjusting means detects the ink temperature detecting means. The perforation energy can be adjusted according to the ink temperature and the type of ink in the printing drum detected by the type of ink in the printing drum (the invention of claim 3).

As a specific example of the ink temperature detecting means, a thermistor is used as proposed in Japanese Patent Application No. 5-109341. It is desirable that the location where the temperature of the ink is detected is a location close to the printed portion, for example, an ink supply unit inside the printing drum.

In the heat-sensitive stencil printing machine according to the second aspect of the invention, an ink temperature detecting means for detecting the temperature of the ink in the printing drum is provided, and the perforation energy adjusting means detects the thermal head temperature detecting means. The perforation energy can be adjusted according to the thermal head temperature, the ink temperature detected by the ink temperature detecting means, and the ink type in the printing drum detected by the ink type detecting means in the printing drum. Invention described).

Further, in the heat-sensitive stencil printing apparatus of the present invention, a thermal head is brought into contact with at least a heat-sensitive stencil master having a thermoplastic resin film, and a minute heating element portion of the thermal head is heated according to an image signal to generate heat. A thermoplastic resin film is position-selectively melt-punched to obtain a punching pattern according to an image signal, the heat-sensitive stencil master is wound around the outer peripheral surface of the printing drum, and ink is supplied from the inner peripheral side of the printing drum, A heat-sensitive stencil printing apparatus for forming an ink image according to an image signal on a printing paper by ink bleeding through a perforation pattern, comprising an ink type setting means in a printing drum and a perforation energy adjusting means (claim (Invention according to item 5).

The ink type setting means in the printing drum is for the user or the like to set the type of ink in advance because the user knows the type of ink in the printing drum in advance. The provided ink type setting key or the like is used.

The perforation energy adjusting means adjusts the perforation energy supplied to the individual heating elements of the thermal head to a predetermined energy according to the ink type in the printing drum set by the ink type setting means in the printing drum. . As the drilling energy adjusting means, specifically, a microcomputer, a microprocessor or the like can be used.

A combination of the ink type detecting means in the printing drum and the perforation energy adjusting means in the thermal stencil printing apparatus according to any one of claims 1 to 4, or the ink type detecting means in the printing drum and the thermal head temperature detecting means and / or the ink temperature. Similar to the configuration of the combination of the detecting means and the perforation energy adjusting means, in the invention according to the fifth aspect, the combination of the ink type setting means in the printing drum and the energy adjusting means for perforation or the ink type setting in the printing drum is set. There is one having the following configuration by a combination of the means and the thermal head temperature detecting means and / or the ink temperature detecting means and the perforation energy adjusting means.

According to a sixth aspect of the present invention, in the heat-sensitive stencil printing apparatus according to the fifth aspect, the thermal head temperature detecting means for detecting the temperature of the thermal head is provided, and the perforation energy adjusting means is the thermal head temperature detecting means. The feature is that the perforation energy is adjusted according to the detected thermal head temperature and the ink type in the print drum set by the ink type in-print drum setting means.

According to a seventh aspect of the present invention, in the heat-sensitive stencil printing apparatus according to the fifth aspect, there is provided ink temperature detecting means for detecting the temperature of the ink inside the printing drum, and the perforation energy adjusting means is the ink temperature detecting means. It is characterized in that the perforation energy is adjusted according to the ink temperature detected by the means and the ink type in the printing drum set by the ink type in the printing drum setting means.

According to an eighth aspect of the present invention, in the heat-sensitive stencil printing apparatus according to the sixth aspect, there is provided ink temperature detecting means for detecting the temperature of the ink in the printing drum, and the perforation energy adjusting means is the thermal head temperature. It is possible to adjust the perforation energy according to the thermal head temperature detected by the detection means, the ink temperature detected by the ink temperature detection means, and the ink type in the printing drum set by the ink type setting means in the printing drum. It has a feature.

Here, the type of ink in the printing drum refers to a type mainly based on a difference in fluidity (or viscosity characteristic) of the ink supplied to the ink supplying means or the like in the printing drum.

In the heat-sensitive stencil printing apparatus according to any one of claims 1 to 8, the perforation energy adjusted to a predetermined energy is supplied by changing the energizing pulse width to the heating element of the thermal head. It may be performed, or may be performed by changing the value of the current flowing through each heating element or the value of the voltage applied to the heating element in accordance with the image signal.

Further, the minute heating elements arranged in the main scanning direction in the thermal head may be of a rectangular type or a heat concentration type.

The heat-sensitive stencil master used in the heat-sensitive stencil printing apparatus according to any one of claims 1 to 8 is a thermoplastic resin film on a porous support such as conventionally known Japanese paper. It is also possible to use a laminate of the above and to integrate them, or to use a heat-sensitive stencil master "consisting essentially of the thermoplastic resin film" (invention according to claim 9). Therefore, the heat-sensitive stencil master has at least the thermoplastic resin film.

In the invention according to claim 9, the thermosensitive stencil master "consisting essentially of the thermoplastic resin film" includes not only the thermoplastic resin film but also the thermoplastic resin film and the antistatic agent. Those containing trace amounts of such components, and further, 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. Including.

[0027]

The operation of the present invention will be described with reference to FIGS. 6 and 7.

In the stencil printing apparatus, the image density of the printed image (ink image) and the degree of the set-off phenomenon, which is a characteristic stain on the back surface of the printing paper, depend on the amount of ink oozing out from the heat-sensitive stencil master. Is determined. The amount of ink that oozes out from the heat-sensitive stencil master is proportional to the opening area of each minute perforation forming the perforation pattern formed in the heat-sensitive stencil master, that is, the size of the perforation.

On the other hand, when the type of ink in the printing drum is different, the amount of ink that oozes out from the perforation pattern formed on the heat-sensitive stencil master is different due to the influence of the fluidity of the ink. In FIG. 6, the vertical axis shows the fluidity of the ink,
Ink temperatures are plotted on the horizontal axis, and characteristic diagrams are shown for three types of inks Ak, Bk, and Ck used in examples described later, with the type of ink in the printing drum as a parameter. . As is clear from the figure, each of the inks Ak, Bk, and Ck has its own ink fluidity value (flow value described later). The degree of fluidity of the ink is as follows: ink Ck> ink Ak> ink Bk
In that order. Therefore, it can be said that the amount of ink that oozes out from the heat-sensitive stencil master is approximately proportional to the size of perforations and the fluidity of the ink for each type of ink (substantially inversely proportional to the viscosity of the ink).

In the present invention, printing is performed by detecting the type of ink in the printing drum by the ink type detecting means in the printing drum or inputting the type of ink in the printing drum by the ink type input means in the printing drum. In order to obtain a uniform and optimal printed image and eliminate the set-off phenomenon for any type of ink in the drum, the perforation pattern is defined according to the unique characteristics such as the fluidity of the ink for each type of ink. The diameter of the perforations to be melted and perforated in the heat-sensitive stencil master is controlled according to the ease with which the ink that oozes out from the printing drum via the. Now, in FIG. 7A, the vertical axis represents the energization pulse width to be applied to each heating element of the thermal head, and the horizontal axis represents the temperature of the ink. As a parameter,
A characteristic diagram for each of the inks Ak, Bk, Ck is shown. In FIGS. 7B and 7C, the inks Ak and B are shown.
Of the inks k and Ck, for example, pay attention to the ink Ak, and the length of the energizing pulse width to be applied corresponding to the case where the fluidity of the ink is small and the case where it is large, the heat-sensitive stencil master 6
The size of the perforation h formed in 1 is shown as a model.

Control of the diameter of the perforation, that is, the perforation h
The size of the ink is set so that the ink has a greater fluidity, that is, the softer it is, the easier it is for the ink to come out of the perforation pattern through the printing drum. By controlling so as to reduce the perforation diameter of the stencil master 61 and reduce the perforation energy applied to the heating element portion of the thermal head, the ink from the heat-sensitive stencil master 61 that has been melt-perforated and made into the printing paper is printed. It suppresses excessive adhesion of the ink, eliminates the set-off phenomenon, and obtains an optimum printed image. On the contrary, the ink has a low fluidity, that is, the harder it is,
Since it becomes difficult for the perforation pattern to come out through the printing drum, if the ink does not come out like this, the perforation diameter of the heat-sensitive stencil master 61 should be increased, that is, for the perforation to be added to the heating element portion of the thermal head. By controlling so as to increase the energy, the adhesion of the ink from the heat-sensitive stencil master 61, which has been perforated and plate-made, to the printing paper is increased, and the blurring of the printed image is eliminated and the optimum printed image is obtained ( (See FIG. 5). This will be specifically described with reference to FIGS. 7A, 7B, and 7C. In the order of ink Ck> ink Ak> ink Bk, which has a large fluidity of ink, the individual heating elements of the thermal head are arranged in order. This means that the energizing pulse width to be applied should be shortened to control the perforation diameter of the heat-sensitive stencil master 61 to be small.

In other words, regardless of the type of ink in the print drum, the punching energy, that is, the optimum print image, depending on the temperature of the thermal head, the temperature of the ink, and the type of ink in the print drum. It is possible to determine the size of perforations in the perforation pattern of the heat-sensitive stencil master that can obtain the set-off phenomenon and eliminate the set-off phenomenon.

As described above, the optimum perforation size of the perforation pattern is determined according to the type of ink in the printing drum, and on the other hand, the size of the perforation is determined by the energy for perforation. Therefore, the type of ink in the printing drum is determined. There is a correspondence relationship between the size of the perforation having the optimum perforation pattern and the energy for perforation, and this correspondence can be experimentally determined.

Most of the heat generated in the heating element of the thermal head is consumed by the melting and perforation of the heat-sensitive stencil master, but a part of the generated heat is also transferred to the thermal head main body and is transferred to the thermal head. Increase the temperature of the main unit. The above-mentioned temperature rise of the thermal head main body is generally not so large, but when the thermal head is continuously operated for a long time, some temperature rise is inevitable. In such a case, the heat generated by the thermal energy of the thermal head body is added to the heat generated by the energy for perforation, so that a perforation larger than the size of the perforation corresponding to the image density of the printed image may be formed. Therefore, when the influence of the temperature rise of the thermal head on the image density is regarded as important, it is necessary to automatically compensate for it.

Further, the ink has a peculiar value of fluidity of ink under the temperature of a specific ink for each ink Ak, Bk, Ck, as shown in FIG. 6, for example. The fluidity changes depending on the temperature. That is, generally, when the temperature of the ink is low, the ink is hard and its fluidity is low (low fluidity), and as the temperature of the ink is high, the ink becomes softer and its fluidity increases (fluidity). Big). In stencil printing, the front side of the heat-sensitive stencil master is brought into contact with the printing paper, ink is supplied from the back side of the heat-sensitive stencil master, and the ink that oozes out from the perforated part of the heat-sensitive stencil master is transferred / attached to the printing paper. Although the printed image is formed by making the ink low in temperature, hard and less fluid, it does not easily pass through the perforated part of the heat-sensitive stencil master, and printing with such ink causes insufficient density of the printed image. Are likely to occur. On the other hand, if you print with an ink that is high in temperature, soft, and highly fluid, the image density becomes unnecessarily high, the resolution of the printed image decreases, and the set-off phenomenon peculiar to the stencil printing machine increases. I will invite you. Therefore, when the influence of the change in the ink temperature on the image density is regarded as important, it is necessary to automatically compensate for it.

Therefore, in consideration of the above points, according to the invention of claim 1, the perforation energy supplied to the individual heating elements of the thermal head by the perforation energy adjusting means is such that the ink type in the printing drum is different. Depending on the type of ink in the printing drum detected by the detection means, an optimal printed image can be obtained for any type of ink in the printing drum, and the size of the perforations that can eliminate the set-off phenomenon can be realized. So that the perforation pattern is formed
It is corrected and adjusted to a predetermined energy.

According to the second aspect of the present invention, the perforation energy adjusting means determines the thermal head temperature detected by the thermal head temperature detecting means and the ink type in the printing drum detected by the ink type in the printing drum. ,
A perforation pattern with a perforation size is formed that provides an optimum print image at any type of ink in the print drum, at any temperature of the thermal head, and at any ambient temperature, and that can eliminate the set-off phenomenon. Thus, the drilling energy is corrected and adjusted to a predetermined energy.

According to the third aspect of the invention, printing is performed by the perforation energy adjusting means according to the ink temperature detected by the ink temperature detecting means and the ink type in the printing drum detected by the ink type detecting means in the printing drum. A perforation pattern with a perforation size that can obtain an optimum printed image regardless of the type of ink in the drum, the temperature of any ink in the drum, and any ambient temperature and that can eliminate the set-off phenomenon As described above, the drilling energy is corrected and adjusted to a predetermined energy.

According to the fourth aspect of the invention, the perforation energy adjusting means detects the thermal head temperature detected by the thermal head temperature detecting means, the ink temperature detected by the ink temperature detecting means, and the ink type detecting means in the printing drum. Depending on the type of ink in the printing drum, the optimum print image can be obtained at any type of ink in the printing drum, any temperature of the thermal head, any temperature of the ink in the drum, and any ambient temperature, as well as set-off. The perforation energy is corrected and adjusted to a predetermined energy so that a perforation pattern having a size of perforations that can eliminate the phenomenon is formed.

According to the fifth aspect of the invention, the perforation energy supplied to the individual heating elements of the thermal head by the perforation energy adjusting means is set in the printing drum ink type setting means by the printing drum ink type setting means. Depending on the type, a predetermined perforation pattern is formed so that an optimal printed image can be obtained with any type of ink in the printing drum, and the perforation size can be eliminated so that the set-off phenomenon can be eliminated. The energy is corrected and adjusted.

According to the sixth aspect of the present invention, the perforation energy adjusting means sets the thermal head temperature detected by the thermal head temperature detecting means and the ink type in the printing drum set by the ink type in the printing drum setting means. Depending on the type of ink in the printing drum, at any temperature of the thermal head and at any ambient temperature, an optimal printed image can be obtained and a perforation pattern with a perforation size that can eliminate the set-off phenomenon. The energy for drilling is corrected and adjusted to a predetermined energy so that a hole is formed.

According to the seventh aspect of the present invention, the perforation energy adjusting means determines the ink temperature detected by the ink temperature detecting means and the ink type in the print drum set by the ink type in the print drum. A perforation pattern having a perforation size that can obtain an optimum printed image regardless of the type of ink in the printing drum, the temperature of any ink in the drum, and any ambient temperature, and that can eliminate the set-off phenomenon. The energy for drilling is corrected and adjusted to a predetermined energy so that a hole is formed.

According to the eighth aspect of the present invention, the perforation energy adjusting means allows the thermal head temperature detected by the thermal head temperature detecting means, the ink temperature detected by the ink temperature detecting means, and the ink type setting means in the printing drum. Depending on the type of ink in the printing drum set in, the optimum print image can be obtained regardless of the type of ink in the printing drum, the temperature of the thermal head, the temperature of any ink in the drum, and any ambient temperature. The perforation energy is corrected and adjusted to a predetermined energy so that a perforation pattern having the size of the perforation that can eliminate the set-off phenomenon is formed.

[0044]

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

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

In the figure, reference numeral 50 indicates an apparatus main body cabinet. The upper portion of the apparatus main body cabinet 50 has a portion indicated by reference numeral 80 which constitutes a document reading portion, the portion indicated by reference numeral 90 therebelow is a plate making plate feeding portion, and the portion indicated by reference numeral 100 on the left side thereof is a porous printing drum. A print drum unit 101 is disposed, a portion 70 on the left side thereof is a plate discharge unit, a portion 110 below the plate making and feeding unit 90 is a paper feed unit, and a portion 120 below the print drum 101 is a portion. Is a printing pressure portion, reference numeral 1 at the lower left of the apparatus main body cabinet 50.
The portions indicated by 30 are the paper discharge portions, respectively.

This heat-sensitive stencil printer is capable of multicolor overprinting of black, red, blue, yellow, etc., and the color of each color can be easily changed by replacing the drum unit. For simplification of description, it is assumed that the three types of ink described in the operation: inks Ak (red), Bk (blue), and Ck (black) are color-changed to perform multicolor printing. Ink Ak (red), Bk (blue),
As described above, Ck (black) has different fluidity depending on the composition and amount of the pigment, which is a component contained in the ink.
Three types of ink Ak (red) in these printing drums,
Measuring the fluidity of Bk (blue) and Ck (black) inks directly with various viscometers or by making use of various ink fluidity measuring methods means that the measuring device is the current technology. It is large and not practical. Therefore, in this embodiment, the indirect measuring means by the ink type detecting means in the printing drum as described below is used.

The ink type detecting means in the printing drum will be described with reference to FIG.

Printing with the black ink Ck is performed by using the drum unit 140. That is, the drum unit 140 includes a print drum 101 in which an ink supply unit (described later) for supplying black ink Ck is arranged, and an ink supply pipe 104 (described later) that rotatably supports the print drum 101. And a rear frame 101A and a front frame 101B, which are hung on both ends of a long plate-shaped gripping frame 101H and rotatably support the print drum 101 via an ink supply tube 104, and a predetermined outside of the rear frame 101A. A small magnet 30 constituting the ink type detecting means in the printing drum, which is attached at a position, and an ink pump device (not shown) fixed to the outside of the front frame 101B and sending the black ink Ck to the ink supply pipe 104. Have.

Similarly, printing with the red ink Ak is performed using the drum unit 141, and printing with the blue ink Bk is performed using the drum unit 142.

That is, the drum unit 141 has a printing drum 101m in which an ink supply unit (described later) for supplying the red ink Ak is arranged, and a printing unit mounted at a predetermined position outside the rear frame 101A. It has a small magnet 31 constituting an ink type detecting means in the drum, an ink pump device (not shown) fixed to the outside of the front frame 101B and sending the red ink Ak to the ink supply pipe 104, and the other drum units. It has the same structure as 140.

The drum unit 142 uses the blue ink B.
an ink supply unit (described later) for supplying k, and a print drum 101n provided therein, and a rear frame 101A.
A small magnet 32, which is attached to a predetermined position on the outer side of the front frame 101B and constitutes the ink type detecting means in the printing drum, and an ink supply pipe 104 fixedly mounted on the outer side of the front frame 101B.
A blue ink Bk to the drum unit 14
It has the same configuration as 0. The details of the drum unit attaching / detaching mechanism are the same as the configuration described in, for example, Japanese Patent Application Laid-Open No. 5-229243, and thus the description thereof is omitted.

On the body side of the heat-sensitive stencil printing machine, the machine body 14
5 are provided. The machine body portion 145 is provided with a bearing support portion 146 that detachably supports the ink supply tube 104 and a holding unit (not shown) that detachably holds the grip frame 101H of each drum unit 140, 141, 142. Each drum unit 140, 141, 142 is provided on the inner wall of the body portion 145.
When attached to 5, each magnet 30, 31, 32
A Hall element sensor group 20 composed of three Hall element sensors 21, 22, and 23, which are attached respectively at positions facing each other, is arranged. The three Hall element sensors 21, 22, 23 are connected to a hole energy adjusting means described later via an electronic circuit (not shown). The Hall element sensor group 20 including the three Hall element sensors 21, 22, and 23 constitutes ink type detection means in the printing drum.

By including the ink type detecting means in the printing drum as described above, for example, when the drum unit 140 of the black ink Ck is attached to the body portion 145, the magnet 30 faces the Hall element sensor 23 of the body portion 145. Then, the Hall element sensor 23 is turned on, whereby it is detected that the drum unit 140 of the black ink Ck is mounted. Similarly, when the drum unit 141 of the red ink Ak is attached to the machine body part 145, the magnet 31 faces the hall element sensor 21 of the machine body part 145, and the hall element sensor 21 is turned on. The drum unit 142 is the body part 1
When attached to the magnet 45, the magnet 32 is attached to the body 1
When the hall element sensor 22 is turned on in opposition to the hall element sensor 22 of 45, it is detected that the drum unit 141 of the red ink Ak and the drum unit 142 of the blue ink Bk are mounted, respectively. As described above, at the time of color change printing, the positions and the number of magnets are arranged so as to be different depending on the number of types of ink (the number of colors of ink in this embodiment) arranged in the drum unit, and By appropriately arranging the Hall element sensor at a predetermined position of the machine body portion 145 facing each other, it is possible to detect a larger number of types of ink in the drum.
The above inks are W / O type emulsion inks.

Next, the operation of this heat-sensitive stencil printing machine will be described below, including its detailed configuration.

First, a document 60 having an image to be printed is set on a document receiving stand (not shown) arranged above the document reading section 80, and a plate-making start key (not shown) is turned on. To be executed. That is, the drum unit 1
No. 00 printing drum 101 rotates in the direction opposite to the arrow A in the figure, and the rear end of the used heat-sensitive stencil master 61b mounted on the outer peripheral surface of the printing drum 101 has a trailing edge of the plate ejection peeling roller pair 71a of the plate ejection unit 70. When approaching 71b, the roller pair 71
While a and 71b are rotating, one of the plate discharge peeling rollers 71b scoops up the rear end of the used heat-sensitive stencil master 61b.
Plate discharge roller pair 73a, 73b and plate discharge peel roller pair 71a, 7 arranged on the left side of the plate discharge roller pair 71a, 71b
1b, a pair of plate discharge conveyor belts 72a, 7 suspended between
The used heat-sensitive stencil master 61b is gradually peeled from the outer peripheral surface of the printing drum 101 by the plate discharge peeling / conveying unit constituted by 2b and the plate discharging box 7 while being conveyed in the direction of arrow Y1.
Then, the so-called plate discharge is completed. At this time, the print drum 101 continues to rotate in the counterclockwise direction. The discharged used heat-sensitive stencil master 61b is then compressed inside the plate discharge box 74 by the compression plate 75.

In parallel with the plate discharging process, the document reading section 80 reads the document. That is, the document 60 set on the document receiving table has a separation roller 81, a pair of front document conveying rollers 82a and 82b, and a pair of rear document conveying rollers 83a and 8a.
Each rotation of 3b is carried in the direction of the arrow Y2 to Y3 and is used for exposure reading. At this time, the original 6
When there are a large number of 0's, only the lowermost original is conveyed by the action of the separating blade 84. When reading the image of the original 60, the reflected light from the surface of the original 60 illuminated by the fluorescent lamp 86 is conveyed while being conveyed on the contact glass 85.
The reflection is performed by the mirror 87, and the light is incident on the image sensor 89 including a CCD (photoelectric conversion element) through the lens 88. That is, when reading the original 60,
The document is read by a known “reduced document reading method”, and the document 60 whose image has been read is discharged onto a document tray 80A. The electric signal photoelectrically converted by the image sensor 89 is set on an analog / digital (A / D) conversion board (not shown) in the apparatus main body cabinet 50 and converted into a digital image signal.

The original reading section 80 has a structure having various functions for color separation necessary for multicolor overprinting, for example, a plurality of color filters described in Japanese Patent Laid-Open No. 64-18682 can be switched. A mirror 87 and a lens 8 have the same functions and configurations as the controllable filter unit.
It is arranged on the optical path between the plate 8 and 8 and carries out operations such as automatic plate making and plate feeding similar to those described in the publication, and detailed description thereof will be omitted.

On the other hand, in parallel with this image reading operation,
A plate making process and a plate supplying process are performed based on the image information converted into a digital signal. The core tube 61s of the master roll 61R, which is wound around the core tube 61s in a roll shape, is rotatably supported by a rotation support member (not shown) arranged at a predetermined portion of the plate making plate feeding section 90, and is heat-sensitive. The stencil master 61 is pulled out from the master roll 61R and is transported to the downstream side of the master transport path by the rotation of the platen roller 92 and the feed roller pair 93a, 93b which are pressed against the thermal head 91 via the heat-sensitive stencil master 61. It With respect to the heat-sensitive stencil master 61 conveyed in this way, a large number of minute heating elements arranged in a line in the main scanning direction of the thermal head 91 are used for the above A / D conversion substrate and subsequent plate-making control (not shown). The thermoplastic resin film of the heat-sensitive stencil master 61, which is selectively heated in accordance with a digital image signal sent after being subjected to various kinds of processing on the substrate, and which is in contact with the heated heating element, is melt-punched. . In this way, the image information is written as a perforation pattern by the position-selective fusion perforation of the heat-sensitive stencil master 61 according to the image information.

The leading end of the plate-making heat-sensitive stencil master 61a in which the image information is written is sent toward the outer peripheral side of the printing drum 101 by the plate feeding roller pair 94a and 94b, and is moved downward by a guide member (not shown). And is drooped toward the expanded master clamper 102 (shown in phantom) of the printing drum 101 in the illustrated plate feeding position. 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 front end of the plate-making heat-sensitive stencil master 61a is clamped by the master clamper 102 at a constant timing, the printing drum 101 is moved to the arrow A in the figure.
The plate-prepared heat-sensitive stencil master 61a is gradually wound around the outer peripheral surface while rotating in the direction (clockwise direction). The rear end of the plate-made heat-sensitive stencil master 61a is cut into a certain length by the cutter 95 after the plate-making is completed. When the one plate-made heat-sensitive stencil master 61a is completely wound around the outer peripheral surface of the printing drum 101, so-called plate feeding is completed.

The printing process is started at the same time when the plate making and plate feeding are completed. First, the printing paper 6 stacked on the paper feed table 51
The uppermost one of the two is the registration roller pair 113 by the paper feed roller 111 and the separation roller pair 112a and 112b.
a, 113b in the direction of the arrow Y4, and by the registration roller pair 113a, 113b at a predetermined timing synchronized with the rotation of the printing drum 101, the printing unit 1
Sent to 20. Printing paper 62 sent out in this way
However, when it comes between the print drum 101 and the press roller 103, the press roller 103, which has been separated from the lower peripheral surface of the print drum 101, is moved upward to be wound around the outer peripheral surface of the print drum 101. The plate-shaped heat-sensitive stencil master 61a is pressed. Thus, the printing drum 101
Black ink Ck oozes out from the perforated part of the plate and the perforated pattern part (both not shown) of the plate-making heat-sensitive stencil master 61a, and this bleeding black ink Ck is transferred to the surface of the printing paper 62 to form a printed image. Black ink image is formed.

At this time, on the inner peripheral side of the printing drum 101, from the ink supply pipe 104 to the ink roller 105 and the doctor roller 106, which respectively constitute ink supply means.
Ink is supplied to the ink fountain 107 formed between and, in the same direction as the rotation direction of the printing drum 101, and
Ink is supplied to the inner peripheral side of the print drum 101 by the ink roller 105 that is in contact with the inner peripheral surface while rotating in synchronization with the rotation speed of the print drum 101.

The printing paper 62 on which the printing image is formed in the printing unit 120 constitutes the paper ejection unit 130,
Counterclockwise rotation of the conveyor belt 117, which is peeled off from the print drum 101 by the paper discharge peeling claw 114 and sucked by the suction fan 118, is wound around the suction paper discharge inlet roller 115 and the suction paper discharge outlet roller 116. Due to
The sheet is conveyed in the direction of the arrow Y5, drops on the sheet discharge tray 52, and is sequentially discharged and stacked. In this way, so-called test printing is completed.

Next, the number of printed sheets is set with a ten-key pad (not shown), and when a print start key (not shown) is turned on, the steps of feeding, printing, and discharging are repeated by the set number of printed sheets in the same process as the trial printing. The black ink Ck stencil printing process is completed.

Next, the drum is appropriately replaced by the same operation based on the same construction as described in JP-A-64-18682, and the stencil printing with the red ink Ak and the blue ink Bk is the same as the above plate making. The desired three-color printed matter is obtained by performing each process of plate feeding, paper feeding, printing, and paper discharging.

As the heat-sensitive stencil master 61, one having a thickness of 40 μm in which a thermoplastic resin film having a thickness of 2 μm is laminated on Japanese paper which is a porous support is used.

Next, with reference to FIGS. 2 and 5, the control structure and process for identifying and detecting the type of ink around the thermal head 91 and in the printing drum to adjust the perforation energy will be described in detail. The platen roller 92 is connected to a master feed motor as a driving unit via a timing belt (not shown). The master feed motor is a stepping motor, and is rotated intermittently or continuously. Therefore, the heat-sensitive stencil master 61
Is moved in the sub-scanning direction orthogonal to the main scanning direction with a predetermined feed pitch by the master feed motor via the platen roller 92.

The thermal head 91 has a resolution of 400 DPI (dots / inch), and the dimensions of the minute heating elements arranged in the main scanning direction are 30 × 40 μm.
The so-called rectangular heating element is used.

With reference to FIGS. 5 (A) and 5 (B), description will be given of a related action between the perforation energy supplied to the individual heating elements of the thermal head 91 and the perforation size of the perforation pattern. Now, referring to FIGS. 5A-3 and 5B-3, these drawings are sectional views showing the structure of the minute heating element portion in the thermal head 91. A portion indicated by reference numeral 1A is a heating element portion formed of a thin layer of a high electric resistance material, reference numeral 1
The portion indicated by B indicates the lead electrode, and the portion indicated by reference numeral 1C indicates the protective film.

The heating element portion 1A is formed on the substrate (hatched portion). When a voltage is applied between the lead electrodes 1B, a current flows in the heating element portion 1A between the lead electrodes 1B, and Joule heat causes the heating element portion 1A in the energized portion to generate heat. In the thermal head 91, such a minute heating element portion 1A is in a direction orthogonal to the paper surface of FIGS. 5 (a-3) and 5 (b-3), that is, FIGS. 5 (a-4) and 5 (b-4). 5 (a-3), the heat-sensitive stencil master 61 is arranged in close proximity to the main scanning direction S at a constant pitch.
A perforation pattern is formed by melt perforation while being conveyed in the left-right direction (sub-scanning direction F) in (b-3).

In the case of the rectangular shape shown in FIG. 5 (b-4), the heating element portion 1A has a size of, for example, 30 μm in the main scanning direction S and 40 μm in the sub-scanning direction F as described above. In the case of the heat concentration type shown in FIG. 5 (a-5) (the central portion of the heating element portion 1a is formed to have a narrow width, the current density is increased in this portion, and heat generation is concentrated in this portion), For example,
The total length of the heating element portion in the sub-scanning direction F is 70 μm, the length of the heating concentrated portion in the same direction is 10 μm, the overall width of the heating element portion in the main scanning direction S is 50 μm, and the width of the heating concentrated portion in the same direction is 15 μm. It has become.

When the energy for perforation is supplied to the heating element portion in the form of electric energy, this energy is converted into heat energy by the heating element portion 1A, and the temperature of the heat-sensitive stencil master 61 in contact with the protective film 1C. Rises. The temperature distribution at this time has a mountain-shaped distribution like a curve Tα shown in FIG. 5 (a-2) and a curve Tβ shown in FIG. 5 (b-2).
As can be easily understood, FIG.
This is a case where the perforation energy supplied to A is relatively small, and FIG. 5B-2 is a case where the perforation energy is relatively large.

The straight line indicated by the symbol D in the figure is the "threshold temperature" at which the thermoplastic resin film of the heat-sensitive stencil master 61 is melt-punched, and the heat-sensitive stencil master 61 is supplied to the heating element portion. Depending on the magnitude of the drilling energy, the small drilling h shown in FIG.
Large perforations h as shown in (b-1) are melted and perforated.

In this way, the size of the perforation h as one unit of the perforation pattern formed in the heat-sensitive stencil master 61 is controlled by adjusting the perforation energy supplied to the individual heating elements of the thermal head 91. it can. This situation is the same whether the heating element is rectangular or heat concentrated.

Next, with reference to FIG. 2, a control configuration and process for identifying and detecting the type of ink in the printing drum and adjusting the energy for punching will be described.

In the figure, reference numeral 5 indicates a microprocessor as a drilling energy adjusting means. The microprocessor 5 includes a CPU (central processing unit) and I / O.
It has a well-known configuration including an (input / output) port, a ROM (read-only memory), a RAM (readable / writable memory), and the like. The microprocessor 5 transmits a command signal and a data signal between the Hall element sensor group 20, the thermal head 91 connected via a thermal head drive circuit (not shown), which will be described later, the thermistor 2, and the thermistor 15. It transmits and receives to detect the temperature of the thermal head 91 and the temperature of the ink pool 107, and to identify and detect the type of ink in the printing drum to control the entire system for adjusting the energy for perforation.

As will be described later, the microprocessor 5 responds to the thermal head temperature detected by the thermistor 2, the ink temperature detected by the thermistor 15, and the ink type in the printing drum detected by the ink type detecting means in the printing drum. It has a function of adjusting the energy for drilling.
Therefore, the ROM of the microprocessor 5 obtains an optimum print image based on the "program for adjusting the energy for punching" and the type of ink in the print drum that is identified and detected, and the set-off phenomenon is prevented. The “relationship with the energy for perforation for perforating the heat-sensitive stencil master 61 according to the kind of ink in the printing drum, the temperature of the thermal head, and the temperature of the ink” to eliminate the perforation has been previously determined experimentally. Remembered

The thermistor 2 has a function as a thermal head temperature detecting means for detecting the temperature of the thermal head 91, and the thermistor 15 has a function as an ink temperature detecting means for detecting an ink temperature in the printing drum 101. .

As shown in FIG. 4, the thermistor 2 is arranged on the thermal head substrate 1, which is a circuit board on which the thermal head 91 is mounted, and detects the temperature of the thermal head 91 main body. In the figure, reference numeral 3 indicates a heating element portion housing portion of the thermal head 91, and reference numeral 4 indicates an aluminum radiator.

The thermistor 15 detects the ink temperature in the ink reservoir 107 formed for each ink color of each ink supply unit.

In FIG. 2, reference numeral 6 indicates a power source, and this power source 6 supplies electric energy corresponding to the punching energy for melting and punching the heat-sensitive stencil master 61 to the thermal head 91 via the thermal head driving circuit. Supply.

The adjustment of the energy for drilling is as described above.
This may be performed by changing the value of the current flowing in each heating element or the value of the voltage applied to the heating element according to the image signal, but in this embodiment, the thermal head 91 is used.
This is performed by changing the pulse width of the energization to the heating element part. That is, the microprocessor 5 includes the hall element sensor group 20.
From the ink type signal in the printing drum, the thermal head temperature data signal output from the thermistor 2, and the ink pools 107 output from the thermistor 15.
The ink temperature data signal of is acquired via the I / O (input / output) port. Then, the microprocessor 5 appropriately outputs the ink type signal in the printing drum, the thermal head temperature data signal and the ink temperature data signal to the above-mentioned RO.
The thermal head 91 is controlled by setting the energizing pulse width capable of punching an appropriate size in the heat-sensitive stencil master 61 while calculating it by the CPU while matching it with M and storing it in the RAM as appropriate. The thermal head 91 receives power supply from the power supply 6 according to the digital image signal and causes the heating element portion to generate heat according to the energization pulse width set by the microprocessor 5.

Next, with reference to FIGS. 8 and 9, a method of determining the energizing pulse width for energizing the thermal head 91 will be described. As shown in FIG. 8, first, in step S10, the type of ink in the print drum is identified and detected.
In step S11, the thermistor 2 detects the temperature of the thermal head 91. In step S12, the thermistor 15 detects the ink temperature. Then, in step S13, the standard pulse width for the temperature of the thermal head 91 (step S11) and the ink temperature (step S12) is determined. Next, in step S14, the microprocessor 5 calculates the value according to the type and the type of the ink in the printing drum identified and detected in step S10 and the standard pulse width obtained in step S13, and applies the thermal head 91 to the thermal head 91. Determine the energizing pulse width to be applied.

Referring to FIG. 9, for example, at certain temperatures A ° C. and B ° C. of the thermal head temperature and the ink temperature, A
A method of setting the energizing pulse width applied to the thermal head 91 in the case of ° C <B ° C will be described. When the standard pulse width of the thermal head temperature and the ink temperature at a certain temperature A ° C. is tp _A and the standard ink type in the printing drum is used, the standard pulse width tp _A is energized. When using the type of ink in the printing drum that easily ejects ink from the printing drum, a pulse width shorter than the standard tp _A -t ₁ is applied, and conversely, printing is performed using the type of ink in the printing drum. When using a material that does not easily eject ink from the drum, a pulse width longer than the standard, tp _A + t ₂ , is applied. When the standard pulse width of the thermal head temperature and the ink temperature at a certain temperature B ° C. is tp _B , and the standard ink type in the printing drum is used, the standard pulse width tp _B is energized. When using a type of ink in the printing drum that is easily ejected from the printing drum, tp _B -t ₃ and a pulse width shorter than the standard are energized, and conversely, depending on the type of ink in the printing drum. When using a print drum that does not easily eject ink, a pulse width longer than the standard tp _B + t ₄ is applied. The standard pulse widths: tp _A and tp _B , the pulse widths to be corrected according to the ink type in the printing drum, the thermal head temperature, and the ink temperature: t ₁ , t ₂ , t ₃ , t _4, etc.
This data was obtained by repeating many experiments.

In this manner, the energizing pulse width to the heating element portion of the thermal head is changed according to the thermal head temperature, the ink temperature, and the type of ink in the printing drum.
As a result of printing, a desired print image having a desired energization pulse width and no offset problem was obtained.

In many of the many repeated experiments described above, the thermal head 91 used had a resolution of 4
00DPI, the size of the heating element was 30 × 40 μm, and the line cycle was 3 ms / line. The applied power (applied power) applied to the heating element is 0.
It was set to 09W.

As described above, the type of ink in the printing drum detected by the type of ink detection in the printing drum, the thermal head temperature detected by the thermistor 2, and the thermistor 1
As an example in which the energy for perforation is set based on the ink temperature detected in No. 5, the experimental environment temperature is 10 ° C, 20 ° C, 3
Ink temperature at 0 ° C, thermal head temperature, energizing pulse width, ink fluidity: spread meter diameter D (J
According to IS-K5701, it is also called a flow value), a heat-sensitive stencil master 61 formed by fusion perforation.
The following is a list of the perforation diameter, the print image density and the print image quality measured as the reflection density by the Macbeth densitometer.

(Ink type in printing drum Ak type) Environmental temperature 10 ° C. 20 ° C. 30 ° C. Ink temperature 11 ° C. 21 ° C. 32 ° C. Thermal head temperature 11 ° C. 21 ° C. 31 ° C. Energizing pulse width (μs) 600 530 460 Ink flow value (Mm) 27.8 29.5 32.2 Perforation diameter (μm) 55 52 48 Print image density 0.95 0.95 0.95 Print image quality Good Good Good (ink type in printing drum Bk type) Environmental temperature 10 ℃ 20 ℃ 30 ℃ Ink temperature 11 ℃ 21 ℃ 32 ℃ Thermal head temperature 11 ℃ 21 ℃ 31 ℃ Energization pulse width (μs) 630 555 480 Ink flow value (mm) 25.6 26.6 28.8 Perforation diameter ( μm) 58 55 50 Printed image density 0.89 0.90 0.90 Printed image quality Good Good Good Good Type Ck type) Environmental temperature 10 ° C 20 ° C 30 ° C Ink temperature 11 ° C 21 ° C 32 ° C Thermal head temperature 11 ° C 21 ° C 31 ° C Energizing pulse width (μs) 570 505 440 Ink flow value (mm) 35.1 38 .2 40.0 Perforation diameter (μm) 52 49 45 Print image density 0.98 0.98 0.99 Print image quality Good Good Good FIGS. 10 and 11 show another embodiment of the present invention.

This embodiment is different from the heat-sensitive stencil printing apparatus of the above embodiment in that the Hall element sensor group 20 and the magnets 30, 31, 32 as the ink type detecting means in the drum.
The main difference is that an ink type setting key 41 as an in-printing-ink-type setting means for setting the type of ink in the printing drum is provided instead. The ink type setting key 41 is for the user or the like to know the type of ink in the print drum in advance and set the type of ink.

The microprocessor 5 supplies the perforation energy to be supplied to the individual heating elements of the thermal head 91,
The energy is adjusted to a predetermined energy according to the type of ink in the printing drum input with the ink type setting key 41.

As shown in FIG. 11, an operation panel 40 for operating the heat-sensitive stencil printing machine is arranged in the upper part of the apparatus main body cabinet. On the operation panel 40,
Ink type setting key 41, numeric keypad 42 for inputting the number of prints, etc., and 7-segment LED for displaying the number of prints etc. input by pressing (turning on) the numeric keypad 42.
A (light emitting diode) display section 43, a plate-making start key 44 for inputting activation of each operation from image reading of an original image to trial printing, and a print start key 45 for activating the printing operation of the number of prints input by the ten keys 42. And an LED lamp group 46 for displaying the ink type in the print drum for displaying the ink type in the print drum which is selectively set by the ink type setting key 41.

The LED lamp group 46 includes LED lamps 46a, 46b and 46c which indicate that the drum units corresponding to three kinds of black inks having different fluidity values: black 1, black 2 and black 3 are selected. LED lamp 46d indicating that the drum unit corresponding to the red ink is selected, and LED lamp 46 indicating that the drum unit corresponding to the blue ink is selected.
The LED lamp 46f indicates that the drum unit corresponding to e and yellow ink is selected. LED lamp 4 when the ink type setting key 41 is pressed once
6a is turned on, and the LED lamp 46b is turned on when the ink type setting key 41 is pressed twice, so that the LED lamps are sequentially turned on each time the ink type setting key 41 is pressed, and printing set by the user is performed. It is displayed that the drum unit corresponding to the type of ink in the drum is selected.

The process of identifying and detecting the type of ink in the printing drum and adjusting the energy for perforation in this embodiment is the same as that of the above embodiment except for the following initial operation contents, and therefore its explanation is omitted. That is, when the user inputs the ink type in the print drum which is known and desired by the ink type setting key 41, the ink type signal in the print drum is input to the microprocessor 5 and
The LED lamp corresponding to the type of ink in the printing drum is turned on.

Also according to this another embodiment, plate making / printing is performed by changing the energizing pulse width to the heating element portion of the thermal head according to the thermal head temperature, the ink temperature and the ink type in the printing drum. In addition, a desired printed image was obtained at a certain specific energization pulse width, and a printed matter having no set-off defect was obtained.

The heat-sensitive stencil master conventionally used is
As described above, it has a laminated structure in which a very thin thermoplastic resin film such as polyester and a Japanese paper fiber or a synthetic fiber as a porous support, or a mixed paper of Japanese paper fiber and a synthetic fiber are laminated. Then, the heat-generating body portion such as a thermal head performs melt perforation, plate making, and printing on the thermoplastic resin film portion.
When there is a portion where the support fibers of the heat-sensitive stencil master are intricately entangled with each other or when the thick fibers of the support fibers are crossed, the passage of the ink is blocked and the ink is printed correctly. Without being transferred to, solid parts may come off, letters or thin lines may be cut or faint,
There is a problem that the image quality is deteriorated due to the phenomenon commonly called fiber grain. Therefore, attempts have been made to reduce the number of fibers by removing the above-mentioned support that generates fibers or by thinning the support.

Further, it is possible to use a heat-sensitive stencil master consisting essentially of a thermoplastic resin film in the heat-sensitive stencil printing apparatus of the above-mentioned embodiment and the above-mentioned another embodiment. Resin film thickness is 2 μm
Using the same, according to the thermal head temperature, the ink temperature and the type of ink in the printing drum, the energizing pulse width to the heating element of the thermal head was changed to perform perforation. It was possible to obtain the desired optimum print image quality with no stain on the printing paper due to set-off. In addition to this effect, it was possible to obtain a good printed image without so-called fibres as described above.

The thermistor 2 may be arranged not only on the thermal head substrate 1 but also inside the aluminum radiator 4.

The means for detecting the type of ink in the printing drum is not limited to the above-mentioned means. For example, a viscometer such as an L-type viscometer or the fluidity of the ink may be provided in the ink reservoir of the ink supplying means inside the printing drum. A measuring unit such as a spread meter for measurement is provided, and the measurement data signal detected by these is converted into an electric, optical, radio wave or magnetic signal and transmitted, and the transmission unit is received on the drum unit side to receive these signals. The receiving units may be provided on the heat sensitive stencil printer main body side.

The ink type detecting means in the printing drum is, for example, the DIP switches 133 and 13 described in FIGS. 3 and 4 of JP-A-6-199028.
5, a code reading / detecting device such as a bar code, a color identification shape portion arranged on the printing drum is identified by a photoelectric sensor,
Alternatively, a color detection sensor or the like that directly detects the color itself of the ink supplied to the printing drum may be provided to detect the type of ink in the printing drum to be used.

Further, the temperature inside the apparatus of the heat-sensitive stencil printing apparatus and / or the environmental temperature outside the apparatus is detected, and for perforation according to this temperature and the ink type in the printing drum detected by the ink type detecting unit in the printing drum. You may make it adjust energy.

If the temperature inside the heat-sensitive stencil printer is stable, the ink temperature is approximately equal to the temperature inside the device. Therefore, instead of detecting the ink temperature, the temperature inside the device is detected to determine the perforation pattern. Even if the size of the perforation is adjusted, the same effect as above can be obtained, but in general, the temperature inside the printing device changes according to the usage condition, and there is a gap between the ink temperature and the device temperature. It is difficult to realize such concentration stabilization as in the embodiment.

In the above embodiments and other embodiments, the case of performing multicolor overprinting has been described, but the present invention is not limited to this, and inks of different colors such as black, red, blue and yellow are used. Therefore, it is needless to say that the heat-sensitive stencil printing apparatus of the present invention can be applied to the case where printing is performed on the printing paper with each single color.

The embodiment of the present invention is not limited to the above-mentioned embodiment and the other embodiments, but when it is not necessary to adjust the energy for fine drilling with high accuracy according to the purpose and application, or each embodiment. When the heat-sensitive stencil printing machine according to the example is used at a substantially constant environmental temperature, only the thermistor 2 as the thermal head temperature detecting means is removed from the heat-sensitive stencil printing machine of the above-mentioned embodiment or the above-mentioned another embodiment. Only the thermistor 15 as the ink temperature detecting means is removed from the heat-sensitive stencil printing apparatus having the above-described structure (the embodiment according to the invention of claim 3 or 7) or the heat-sensitive stencil printing apparatus of the above-mentioned embodiment or the above-mentioned other embodiment. The heat-sensitive stencil printing apparatus having the structure (the embodiment according to the invention of claim 2 or 6) or the heat-sensitive stencil printing apparatus of the above-mentioned embodiment or the above-mentioned other embodiment is used for the thermistor 2 and Mista 15 only stencil printing apparatus in which to remove may be (Example according to the invention of claim 1 or 5, wherein).

[0105]

As described above, according to the first to eighth aspects of the invention, due to the above configuration and operation, the change of the ink type in the print drum, the thermal head temperature and / or the ink temperature changes in the print image density. Depending on the degree of influence, the perforation energy is adjusted and adjusted by the perforation energy adjusting means to a predetermined energy according to the type of ink in the printing drum or the type of ink in the printing drum, the thermal head temperature and / or the ink temperature. , It is not necessary to change the mechanical conditions such as the technology to mechanically adjust the pressure contact force between the heat-sensitive stencil master and the printing paper in the conventional printing unit, and it is easy even if the type of ink in the printing drum is different. Further, it is possible to surely obtain an optimum and good printed image, and it is possible to obtain a printed matter having no set-off trouble peculiar to a stencil printing machine.

According to the ninth aspect of the invention, since the heat-sensitive stencil master consisting essentially of the thermoplastic resin film is used, in addition to the above effects, a so-called good fiber-free printed image can be obtained. You can

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a heat-sensitive stencil printing apparatus to which an embodiment of the present invention is applied.

FIG. 2 is a block diagram showing a control configuration of the heat-sensitive stencil printing apparatus.

FIG. 3 is a configuration diagram illustrating an example of an ink type detection unit in a printing drum.

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

5A and 5B are views for explaining the structure of the thermal head and the punching action.

FIG. 6 is a characteristic diagram relating to ink fluidity and ink temperature, with the type of ink in the printing drum as a parameter.

FIG. 7 (a) is a characteristic diagram relating to the thermal head energizing pulse width and the temperature of ink with the type of ink in the printing drum as a parameter, and FIGS. 7 (b) and 7 (c).
[Fig. 3] is a plan view for explaining a perforated state of the heat-sensitive stencil master based on the length of the energization pulse width.

FIG. 8 is a flowchart for determining the energization pulse width applied to the thermal head.

FIG. 9: Temperature A of thermal head temperature and ink temperature
It is a figure for demonstrating the setting method of the energization pulse width applied to a thermal head in ° C and B ° C (A ° C <B ° C).

FIG. 10 is a block diagram showing a control configuration of a heat-sensitive stencil printing machine to which another embodiment of the present invention is applied.

FIG. 11 is a plan view showing a configuration of an operation panel arranged in the heat-sensitive stencil printing machine of the another embodiment.

[Explanation of symbols]

DESCRIPTION OF REFERENCE NUMERALS 1A heating element part of thermal head 2 thermistor as thermal head temperature detecting means 5 microprocessor as punching energy adjusting means 15 thermistor as ink temperature detecting means 20 Hall element sensor group 30, which constitutes ink type detecting means in printing drum, Reference numerals 31 and 32 Magnets constituting the ink type detecting means in the printing drum 41 Ink type setting keys as ink type setting means in the printing drum 61 Heat-sensitive stencil master 91 Thermal head 101 Printing drum 107 Ink pool 140, 141, 142 Drum unit Ak, Bk, Ck Ink type in the printing drum F Sub-scanning direction S Main-scanning direction

Claims (9)

[Claims] 1. A thermal head is brought into contact with a heat-sensitive stencil master having at least a thermoplastic resin film, and a minute heating element portion of the thermal head is caused to generate heat in accordance with an image signal to position-select the thermoplastic resin film. To obtain a perforation pattern according to the image signal by melt perforation, winding the heat-sensitive stencil master around the outer peripheral surface of the printing drum, supplying ink from the inner peripheral side of the printing drum, through the perforation pattern In a heat-sensitive stencil printer that forms an ink image corresponding to the image signal on a printing paper by the ink that has oozing out, an ink type detection unit in the printing drum that detects the type of ink in the printing drum, and the thermal The perforation energy supplied to each heating element of the head is detected by the ink type detecting means in the printing drum, and the ink type in the printing drum is detected. Thermal stencil printing apparatus characterized by having a drilling energy adjusting means for adjusting a predetermined energy in accordance with the. 2. The heat-sensitive stencil printing apparatus according to claim 1, further comprising a thermal head temperature detecting means for detecting a temperature of the thermal head, wherein the perforation energy adjusting means is thermal detected by the thermal head temperature detecting means. A heat-sensitive stencil printing apparatus, wherein the perforation energy is adjusted according to the head temperature and the type of ink in the printing drum detected by the type of ink in the printing drum. 3. The heat-sensitive stencil printing apparatus according to claim 1, further comprising an ink temperature detecting means for detecting a temperature of ink in the printing drum, wherein the perforation energy adjusting means is detected by the ink temperature detecting means. A heat-sensitive stencil printing apparatus, wherein the perforation energy is adjusted according to the ink temperature and the ink type in the printing drum detected by the ink type detecting means in the printing drum. 4. The heat-sensitive stencil printing apparatus according to claim 2, further comprising an ink temperature detecting means for detecting the temperature of the ink in the printing drum, wherein the perforation energy adjusting means is the thermal head temperature detecting means. It is characterized in that the perforation energy is adjusted according to the detected thermal head temperature, the ink temperature detected by the ink temperature detecting means, and the ink type in the printing drum detected by the ink type detecting means in the printing drum. Thermal stencil printer. 5. A thermal head is brought into contact with a heat-sensitive stencil master having at least a thermoplastic resin film, and a minute heating element portion of the thermal head is caused to generate heat in accordance with an image signal to position-select the thermoplastic resin film. To obtain a perforation pattern according to the image signal by melt perforation, winding the heat-sensitive stencil master around the outer peripheral surface of the printing drum, supplying ink from the inner peripheral side of the printing drum, through the perforation pattern In a heat-sensitive stencil printer that forms an ink image corresponding to the image signal on a printing paper by the ink that has oozing out, an ink type setting unit in the printing drum for setting the type of ink in the printing drum, The perforation energy supplied to the individual heating elements of the thermal head is set in the printing drum ink set by the printing drum ink type setting means. Thermal stencil printing apparatus characterized by having a drilling energy adjusting means for adjusting a predetermined energy in accordance with the key type. 6. The thermal stencil printing apparatus according to claim 5, further comprising a thermal head temperature detecting means for detecting the temperature of the thermal head, wherein the perforation energy adjusting means is detected by the thermal head temperature detecting means. A heat-sensitive stencil printing apparatus, wherein the perforation energy is adjusted according to the thermal head temperature and the type of ink in the printing drum set by the type of ink in the printing drum. 7. The heat-sensitive stencil printing apparatus according to claim 5, further comprising an ink temperature detecting means for detecting a temperature of ink in the printing drum, wherein the perforation energy adjusting means is detected by the ink temperature detecting means. A heat-sensitive stencil printing apparatus, wherein the perforation energy is adjusted according to the ink temperature and the ink type in the printing drum set by the ink type setting means in the printing drum. 8. The heat-sensitive stencil printing apparatus according to claim 6, further comprising an ink temperature detecting means for detecting the temperature of ink in the printing drum, wherein the perforation energy adjusting means is the thermal head temperature detecting means. It is possible to adjust the perforation energy according to the detected thermal head temperature, the ink temperature detected by the ink temperature detection means, and the ink type in the printing drum set by the ink type setting means in the printing drum. Characteristic thermal stencil printer. 9. The heat-sensitive stencil printing apparatus according to claim 1, wherein the heat-sensitive stencil master is substantially composed of a thermoplastic resin film. .