JP2019038205A - Stencil printing device - Google Patents

Abstract

To prevent reduction of a density of a print image.SOLUTION: A stencil printing device includes: a control part 10 which controls a thermal head 23 so as to reduce a perforation diameter for heat-perforating a master in response to an increase in a temperature of the thermal head 23; a calculation part 103 which calculates a temperature difference between the temperature of the thermal head and an ink temperature; and an idling control part 104 which executes more idling operation of rotating a drum 32 in a state that a confidential master as a master which is not heat-perforated by the thermal head 23 is attached to an outer peripheral surface of the drum 32 when the temperature difference calculated by the calculating part 103 is a predetermined threshold or more as compared with when the temperature difference is less than the predetermined threshold.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a stencil printing apparatus that prevents a decrease in density of a printed image.

  The stencil printing apparatus makes a plate by heating and perforating a stencil sheet (master) with a thermal head based on the image data, and the stencil master makes a plate on the outer peripheral surface of the drum. In the drum, a doctor roller and an ink roller that rotate in synchronization with the rotation of the drum are provided. Then, while supplying ink from the ink tank to the master punched by heating through the doctor roller and the ink roller, paper is supplied to the rotating drum, and this paper is pressed against the drum by the pressing roller for printing. Do.

  In this way, in the stencil printing apparatus, since the plate is made by heating and punching the master with the thermal head, the temperature of the thermal head itself also rises.

  Further, in a stencil printing apparatus, continuous printing with a large number of prints per master is often performed. In the case of continuous printing, the number of rotations of the drum increases according to the number of printed sheets. When the number of rotations of the drum increases, the temperature of the ink supplied by the rotation of the doctor roller and the ink roller easily increases, and the viscosity of the ink decreases as the ink temperature increases. When the viscosity of the ink is lowered, the ink is easily discharged from the outer peripheral surface of the drum, and image deterioration such as an excessive amount of ink may occur in the printed image.

  Therefore, in the case of continuous printing, based on the temperature of the thermal head so that the diameter of the heat punched by the master becomes small, assuming that the viscosity of the ink decreases as the temperature of the thermal head increases. Control is often performed to reduce the energy applied to the thermal head.

  Japanese Patent Application Laid-Open No. 2005-228561 discloses a technique that includes detection means for detecting temperature information of a thermal head, and changes the input energy to the thermal head based on the detected temperature of the thermal head.

JP 2006-142686 A

  However, even a stencil printing apparatus may perform small lot printing with a small number of prints per master. In the case of small lot printing, since a plurality of masters are heated and punched in a short time, the temperature of the thermal head tends to rise.

  On the other hand, since the number of rotations of the drum per master is reduced, the number of rotations of the doctor roller and the ink roller is reduced, the temperature of the ink supplied from the ink tank is difficult to rise, and the viscosity of the ink is lowered. hard.

  For this reason, as in the technique described in Patent Document 1, if the input energy to the thermal head is merely changed based on the detected temperature of the thermal head, the temperature of the thermal head can be reduced, for example, during small lot printing. On the other hand, when the ink temperature does not rise, the viscosity of the ink is high and it is difficult to discharge the ink from the outer peripheral surface of the drum. As a result, the printed image may have a reduced density.

  In this case, in order to raise the ink temperature, a secret master, which is a master that is not heated and perforated by a thermal head, is placed on the outer peripheral surface of the drum, and an idling operation of rotating the drum while pressing the secret master is performed. Conceivable. The ink temperature rises as the number of idling operations increases (as the number of rotations of the drum increases). Therefore, in order to obtain an appropriate ink temperature, it is necessary to determine an appropriate number of idling times.

  The present invention has been made in view of such a problem, and performs an idling operation an appropriate number of times to prevent a decrease in the density of a printed image regardless of the number of prints per master. An object of the present invention is to provide a stencil printing apparatus capable of performing the above.

In order to achieve the above object, the first feature of the stencil printing apparatus according to the present invention is:
A thermal head for heating and punching an image based on image data in a master made of stencil paper;
The drum that is heated and perforated in the thermal head is attached to the outer peripheral surface, and a drum that prints on a printing paper by rotating while supplying ink to the master; and
Ink temperature acquisition means for acquiring the temperature of the ink;
Thermal head temperature acquisition means for acquiring the temperature of the thermal head;
Calculating means for calculating a temperature difference between the temperature of the thermal head and the temperature of the ink;
The idling operation of rotating the drum in a state where the confidential master that is not heated and punched by the thermal head is fixed on the outer peripheral surface of the drum, the temperature difference calculated by the calculating means is equal to or greater than a predetermined threshold value If it is, the idling control means to be executed more than when the temperature difference is less than a predetermined threshold;
It is in having.

  According to the first feature of the image forming apparatus according to the present invention, it is possible to prevent a decrease in the density of a printed image.

It is an apparatus block diagram which shows the hardware constitutions of the stencil printing apparatus which is Example 1 of this invention. It is a functional block diagram which showed the functional structure of the stencil printing apparatus which concerns on Example 1 of this invention. It is the figure which showed calculation of the temperature difference by the calculation part with which the stencil printing apparatus which concerns on Example 1 of this invention is provided. It is the flowchart which showed the process sequence in the stencil printing apparatus which concerns on Example 1 of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. Throughout the drawings, the same or equivalent parts and components are denoted by the same or equivalent reference numerals. However, it should be noted that the drawings are schematic and different from the actual ones. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  Further, the embodiment described below exemplifies an apparatus or the like for embodying the technical idea of the present invention, and the technical idea of the present invention includes the material, shape, structure, The layout is not specified as follows. The technical idea of the present invention can be variously modified within the scope of the claims.

<Configuration of stencil printing machine>
A configuration of a stencil printing apparatus that is Embodiment 1 of the present invention will be described.

  FIG. 1 is an apparatus configuration diagram illustrating a hardware configuration of a stencil printing apparatus that is Embodiment 1 of the present invention.

  As shown in FIG. 1, the stencil printing apparatus 1 includes a plate making unit 2, a printing unit 3, a paper feeding unit 4, a paper discharging unit 5 and a plate discharging unit 6.

  The plate making unit 2 includes a base paper storage unit 22 that stores a rolled long stencil sheet (master) 21, a thermal head 23 that is disposed downstream of the base paper storage unit 22, and the thermal head 23. A platen roll 24 arranged at a position, a pair of base paper feed rolls 25 arranged downstream of the transport of the platen roll 24 and the thermal head 23, a light pulse motor 26 for rotating the platen roll 24 and the base paper feed roll 25, and , A base paper cutter 27 disposed downstream of the pair of base paper feed rolls 25 and a thermometer 28 for measuring the temperature of the thermal head 23.

  Then, the plate making unit 2 conveys the long stencil sheet 21 by the rotation of the platen roll 24 and the base paper feed roll 25. Then, based on the image data read by an image reading unit (not shown) and the image data included in the received print job, each dot-like heating element of the thermal head 23 selectively performs a heat generating operation so that the stencil sheet 21 is thermally perforated. And make a plate. Thereafter, the stencil sheet 21 thus made is cut with a stencil sheet cutter 27 to produce a stencil sheet 21 having a predetermined length.

  The printing unit 3 includes a drum 32 that rotates in the direction of arrow A in FIG. 1 by the driving force of the main motor 31, and a base paper clamp unit 33 that is provided on the outer peripheral surface of the drum 32 and clamps the front end of the stencil base paper 21. ing.

  The printing unit 3 includes a base paper confirmation sensor 34 that detects whether or not the stencil paper 21 is wound around the outer peripheral surface of the drum 32, a reference position detection sensor 35 that detects the reference position of the drum 32, and a main motor. And a rotary encoder 36 that outputs a pulse signal at a predetermined period in accordance with the rotation of 31. The rotation angle of the drum 32 can be calculated by detecting the output pulse signal of the rotary encoder 36 based on the detection output (reference position pulse signal) of the reference position detection sensor 35.

  The printing unit 3 includes an ink bottle 15, an ink pump 16, a squeegee roller 17, a doctor roller 18, an ink driving rod 19, and an environmental thermometer 14.

  The ink bottle 15 contains ink used for printing, and the ink in the ink bottle 15 is supplied to the squeegee roller 17 by the ink pump 16. The ink pump 16 is driven by a motor (not shown).

  The squeegee roller 17 supplies ink from the ink bottle 15 to the inner peripheral surface of the drum 32. The squeegee roller 17 is disposed such that the lower end portion of the outer peripheral surface thereof is in contact with the inner peripheral surface of the drum 32.

  The doctor roller 18 is for forming an ink reservoir with the squeegee roller 17. The doctor roller 18 is disposed on the upper left side of the squeegee roller 17 with a predetermined gap. When ink is supplied from the ink bottle 15 to the squeegee roller 17 by the ink pump 16, the supplied ink forms an ink reservoir, and the ink from the ink reservoir passes through a gap between the squeegee roller 17 and the doctor roller 18 and is drummed. 32 is supplied to the inner peripheral surface.

  The ink driving rod 19 is for making the vortex generated in the ink in the ink pool uniform and supplying an appropriate amount of ink to the inner peripheral surface of the drum 32. The ink drive bar 19 is disposed at a position where an ink reservoir between the squeegee roller 17 and the doctor roller 18 is formed.

  The environmental thermometer 14 measures the temperature in the drum 32.

  Further, the printing unit 3 has a press roll 37 disposed below the drum 32. The press roll 37 is configured to be able to change between a pressing position where the pressing force is applied to the outer peripheral surface of the drum 32 by a driving force of the solenoid unit 38 and a standby position which is separated from the outer peripheral surface of the drum 32. The press roll 37 is shifted from the standby position to the pressing position in synchronization with the paper feeding operation from the paper feeding unit 4, and is positioned at the pressing position only when the paper 41 passes through the lower part of the drum 32. It is designed to be positioned.

  The front end of the stencil sheet 21 conveyed from the plate making unit 2 is clamped by a stencil sheet clamping unit 33, and the drum 32 is rotated in this clamped state so that the stencil sheet 21 is wound around the outer peripheral surface of the drum 32. Then, while the ink is supplied from the ink bottle 15 through the squeegee roller 17 to the inner peripheral surface of the drum 32, the paper 41 fed from the paper feeding unit 4 in synchronization with the rotation of the drum 32 is pressed by the press roll 37. By pressing the stencil sheet 21, which is stenciled on the drum 32, ink is transferred to the sheet 41 from the perforations of the stencil sheet 21 and an image is printed.

  The paper feed unit 4 is installed along the paper width direction, a paper feed base 42 on which the paper 41 is stacked, primary paper feed rolls 43 and 44 that transport only the uppermost paper 41 from the paper feed base 42. The paper separating plate 49 for feeding the paper 41 fed from the primary paper feed rolls 43 and 44 one by one and the paper 41 conveyed by the primary paper feed rolls 43 and 44 are synchronized with the rotation of the drum 32. A pair of secondary paper feed rolls 45 transported between the drum 32 and the press roll 37, a paper feed sensor 46 for detecting whether or not the paper 41 has been transported between the pair of secondary paper feed rolls 45, and a paper feed And a paper presence / absence sensor 48 that detects the paper 41 stacked on the paper base 42.

  Further, on the upstream side in the transport direction of the primary paper feed rolls 43 and 44, the paper 41 abutting among the plurality of sheets 41 placed on the paper feed table 42 is fed toward the downstream side in the transport direction. An upstream assist roll 71 is provided. Further, between the primary paper feed rolls 43 and 44 and the secondary paper feed roll 45 in the transport direction, it is installed coaxially with the paper spreading plate 49 in the paper width direction. A downstream assist roll 73 is provided that conveys the received paper 41 from the lower side to the secondary paper feed roll 45.

  The rotation of the main motor 31 is selectively transmitted to the primary paper feed rolls 43 and 44 via a paper feed clutch 47.

  The paper discharge unit 5 includes a paper separation claw 51 that separates the printed paper 41 from the drum 32, a paper discharge roll 52 that conveys the paper 41 separated from the drum 32 by the paper separation claw 51, and the paper discharge roll A paper discharge motor 55 for driving the paper, a paper jam detection sensor 53 for detecting whether or not the paper 41 passes over the paper discharge roll 52, and the paper 41 discharged by the paper discharge roll 52 are placed. A paper discharge tray 54.

  Further, the paper discharge roll 52 is provided with a paper discharge fan 52 a that sucks the paper 41 toward the paper discharge roll 52 so that it can be discharged by the paper discharge roll 52.

  The paper jam detection sensor 53 detects whether or not the paper 41 printed by the printing unit 3 is correctly conveyed.

  The plate discharging unit 6 guides the leading end of the stencil sheet 21 unclamped from the outer peripheral surface of the drum 32, and transports the guided stencil sheet 21 while being peeled off from the drum 32, and this plate discharging transport. A stencil box 62 for storing the stencil sheet 21 conveyed by the means 61 and a stencil compression member 63 for pushing the stencil sheet 21 conveyed into the stencil box 62 by the stencil conveying means 61 into the stencil box 62 are provided. Have.

  FIG. 2 is a functional configuration diagram illustrating a functional configuration of the stencil printing apparatus 1 according to the first embodiment of the present invention.

  As shown in FIG. 2, the stencil printing apparatus 1 according to the first embodiment of the present invention includes a control unit 10 and a storage unit 11.

  The storage unit 11 is an ink temperature table for predicting the ink temperature supplied from the ink bottle 15 from the average temperature in the drum 32 within a predetermined time (for example, the last two hours) and the rotation speed of the drum 32. Is remembered. That is, it shows how many degrees the drum 32 rotates at a certain average temperature and how much the ink temperature becomes.

  In addition, the storage unit 11 includes, as an operation log of the stencil printing apparatus 1, time data, rotation angle data based on the output pulse signal of the rotary encoder 36, and temperature in the drum 32 measured by the environmental thermometer 14. Are stored in association with each other.

  The control unit 10 performs central control of the stencil printing apparatus 1. The control unit 10 controls the plate making unit 2 to make the stencil sheet (master) 21 by performing heat sensitive perforation based on the image data, so that each point-like heating element of the thermal head 23 selectively generates heat. At this time, as will be described later, the control unit 10 causes the thermal head to reduce the diameter of the stencil sheet (master) 21 to be punched by heating in accordance with the temperature rise of the thermal head 23 acquired by the thermometer 28. 23 is controlled. Further, the control unit 10 prints on the paper 41 by rotating the drum 32 and pressing it with the press roll 37 while supplying ink from the ink bottle 15 to the stencil paper (master) 21 that has been heated and punched.

  Moreover, the control part 10 has the thermal head temperature acquisition part 101, the ink temperature acquisition part 102, the calculation part 103, and the idling control part 104 on the function.

  The thermal head temperature acquisition unit 101 acquires the temperature of the thermal head 23 measured by the thermometer 28.

  The ink temperature acquisition unit 102 acquires the ink temperature supplied from the ink bottle 15. For example, the ink temperature acquisition unit 102 calculates the rotation speed of the drum 32 within a predetermined period (for example, the latest 2 hours) based on the rotation angle data of the drum 32 stored in the storage unit 11. Further, the ink temperature acquisition unit 102 is based on the temperature in the drum 32 measured by the environmental thermometer 14 stored in the storage unit 11, and the average temperature of the drum 32 within a predetermined period (for example, the latest 2 hours). Is calculated. Then, the ink temperature acquisition unit 102 refers to the ink temperature table, and calculates the number of rotations of the drum 32 within the predetermined period and the average temperature of the drum 32 within the calculated predetermined period (for example, the latest two hours). From this, the ink temperature supplied from the ink bottle 15 is acquired.

  The calculation unit 103 calculates a temperature difference between the temperature of the thermal head 23 measured by the thermometer 28 and the ink temperature acquired by the ink temperature acquisition unit 102 when printing is requested based on the print job. .

  FIG. 3 is a diagram for explaining the calculation of the temperature difference by the calculation unit 103. FIG. 3 shows changes in the temperature 201 of the thermal head 23 with respect to time, changes in the ink temperature 202 during continuous printing, and changes in the ink temperature 203 during small lot printing.

  As shown in FIG. 3, when the plate making process is executed by the plate making unit 2, the temperature 201 of the thermal head 23 rises. In the stencil printing apparatus 1, continuous printing with a large number of prints per master is often performed, but in the case of continuous printing, the number of rotations of the drum increases in accordance with the number of prints. As the number of rotations of the drum increases, the ink temperature 202 supplied by the rotation of the doctor roller 18 and the squeegee roller 17 also increases following the temperature increase of the temperature 201 of the thermal head 23. In this case, the temperature difference T2 between the temperature of the thermal head 23 measured by the thermometer 28 and the ink temperature acquired by the ink temperature acquisition unit 102 becomes small.

  On the other hand, the stencil printing apparatus 1 may perform small lot printing with a small number of prints per master. In the case of small lot printing, since a plurality of masters are heated and punched in a short time, the temperature of the thermal head 23 is likely to rise. On the other hand, since the number of rotations of the drum per master is small, the ink temperature 203 supplied by the rotation of the doctor roller 18 and the squeegee roller 17 is difficult to rise. That is, in the case of small lot printing, the difference T1 between the temperature 201 of the thermal head 23 and the ink temperature 203 becomes large.

  For this reason, the control unit 10 assumes that the ink temperature rises following the temperature rise of the temperature 201 of the thermal head 23, and when the temperature 201 of the thermal head 23 rises, the diameter of the hole punched by the master is reduced. Control is performed so that the energy applied to the thermal head 23 is reduced.

  However, when the control is made to reduce the energy applied to the thermal head 23 in accordance with the temperature rise of the temperature 201 of the thermal head 23 in this way, the difference between the temperature 201 of the thermal head 23 and the ink temperature 203 increases. In this case, that is, when the ink temperature does not rise as expected, the viscosity of the ink is higher than expected, the ink is difficult to be discharged from the outer peripheral surface of the drum, and image degradation such as density reduction may occur in the printed image.

  Therefore, the calculation unit 103 calculates the temperature difference between the temperature of the thermal head 23 measured by the thermometer 28 and the ink temperature acquired by the ink temperature acquisition unit 102 when printing is requested based on the image data. calculate.

  When the temperature difference T2 calculated by the calculation unit 103 is less than the predetermined threshold Th, for example, the ink temperature increases following the temperature of the thermal head 23 as shown by the ink temperature change 202 in FIG. Therefore, the idling control unit 104 executes the idling operation as many times as the number of idling times set in the normal state. Here, in the idling operation, a secret master, which is a master that is not punched, is made to plate on the drum 32. The operation means that the drum 32 is pressed by the press roll 37 via the secret master while the drum 32 is rotated in a state where the secret master is fixed. Note that the number of times of idling in the normal state is set in advance to an appropriate number of times such as “0” to “5” (times), for example. When “0” is set, the idling operation at the normal time is omitted.

  On the other hand, when the temperature difference T1 calculated by the calculation unit 103 is equal to or greater than the predetermined threshold Th, for example, as shown by the ink temperature change 203 in FIG. 3, the ink temperature increases following the temperature of the thermal head 23. Therefore, the idling operation is executed by adding a predetermined number of times to the idling number in the normal state.

  By this idling operation, the viscosity of the ink that did not pass through the ink hole of the drum 32 or the master hole is reduced, and the ink is easily discharged from the ink hole of the drum 32 or the master hole, so that the density of the printed image is reduced. The occurrence of image degradation can be prevented.

  FIG. 4 is a flowchart showing a processing procedure in the control unit 10 of the stencil printing apparatus 1 according to the first embodiment of the present invention.

  As shown in FIG. 4, when the control unit 10 receives a print job from a computer (not shown) connected via a network (step S101; YES), the thermal head temperature acquisition unit 101 is measured by the thermometer 28. The temperature of the thermal head 23 obtained is acquired (step S103).

  Next, the ink temperature acquisition unit 102 acquires the ink temperature supplied from the ink bottle 15 (step S105).

  Then, the calculation unit 103 calculates a temperature difference between the temperature of the thermal head 23 acquired by the thermal head temperature acquisition unit 101 and the ink temperature acquired by the ink temperature acquisition unit 102 (step S107). Thereby, when printing is requested based on the print job, the calculation unit 103 can calculate the temperature difference between the temperature of the thermal head 23 and the ink temperature.

  Next, the idling control unit 104 determines whether or not the temperature difference calculated by the calculation unit 103 is greater than or equal to a predetermined threshold Th (step S109).

  In step S109, when it is determined that the temperature difference calculated by the calculation unit 103 is less than the predetermined threshold Th (NO), the idling control unit 104 sets the idling number in the normal time (step S111). Specifically, the idling control unit 104 normally attaches the secret master, which is a master that is not heated and punched by the thermal head 23, to the outer peripheral surface of the drum 32, and normally presses the drum 32 while pressing the secret master by the press roll 37. Rotates the number of idling times.

  On the other hand, when it is determined in step S109 that the temperature difference calculated by the calculation unit 103 is equal to or greater than the predetermined threshold Th (YES), the number of times that the idling control unit 104 is added the predetermined number of times to the idling number of normal times. Only the idling operation is executed (steps S113 and S115). Specifically, the idling control unit 104 normally attaches the secret master, which is a master that is not heated and punched by the thermal head 23, to the outer peripheral surface of the drum 32, and normally presses the drum 32 while pressing the secret master by the press roll 37. It rotates the number of times that is added a predetermined number of times to the idling number of hours.

  Thereafter, the control unit 10 controls the plate making unit 2 and the plate discharging unit 6 to discharge the secret master, and performs plate making based on the received print job (step S117).

  The control unit 10 controls the printing unit 3, the paper feeding unit 4, and the paper discharging unit 5 to perform printing by bringing the drum 32 into pressure contact with the paper 41 fed by the paper feeding unit 4. (Step S119).

  In this embodiment, a print job is received from a computer connected via a network. However, a print job may be received by scan printing or USB communication.

As described above, in the stencil printing apparatus 1 according to the first embodiment of the present invention, the calculation unit 103 calculates the temperature difference between the temperature of the thermal head 23 and the ink temperature, and the idling control unit 104
The temperature difference calculated by the calculation unit 103 is equal to or greater than a predetermined threshold value in the idling operation in which the confidential master, which is a master that is not heated and perforated by the thermal head 23, is set on the outer peripheral surface of the drum. In some cases, the temperature difference is executed more than when the temperature difference is less than a predetermined threshold.

  Thus, an appropriate number of idling operations can be performed regardless of the ink temperature. This idling operation lowers the viscosity of the ink that did not pass through the drum ink holes and master holes, making it easier for ink to come out of the drum ink holes and master holes. The occurrence of deterioration can be prevented.

(Appendix)
The present application discloses the following inventions.

(Appendix 1)
A thermal head for heating and punching an image based on image data in a master made of stencil paper;
The drum that is heated and perforated in the thermal head is attached to the outer peripheral surface, and a drum that prints on a printing paper by rotating while supplying ink to the master; and
Ink temperature acquisition means for acquiring the temperature of the ink;
Thermal head temperature acquisition means for acquiring the temperature of the thermal head;
Calculating means for calculating a temperature difference between the temperature of the thermal head and the temperature of the ink;
The idling operation of rotating the drum in a state where the confidential master that is not heated and punched by the thermal head is fixed on the outer peripheral surface of the drum, the temperature difference calculated by the calculating means is equal to or greater than a predetermined threshold value If it is, the idling control means to be executed more than when the temperature difference is less than a predetermined threshold;
A stencil printing apparatus comprising:

DESCRIPTION OF SYMBOLS 1 Stencil printing apparatus 2 Plate making part 3 Printing part 4 Paper feed part 5 Paper discharge part 6 Paper discharge part 10 Control part 11 Storage part 14 Environment thermometer 15 Ink bottle 16 Ink pump 17 Squeegee roller 18 Doctor roller 19 Ink drive rod 21 Stencil paper ( Master)
22 Base Paper Storage Unit 23 Thermal Head 24 Platen Roll 25 Roll 26 Light Pulse Motor 27 Base Paper Cutter 28 Thermometer 32 Drum 33 Base Paper Clamp Unit 34 Base Paper Check Sensor 35 Reference Position Detection Sensor 36 Rotary Encoder 37 Press Roll (Pressing Roller)
101 Thermal Head Temperature Acquisition Unit 102 Ink Temperature Acquisition Unit 103 Calculation Unit 104 Idling Control Unit

Claims (1)

A thermal head for heating and punching an image based on image data in a master made of stencil paper;
The drum that is heated and perforated in the thermal head is attached to the outer peripheral surface, and a drum that prints on a printing paper by rotating while supplying ink to the master; and
Ink temperature acquisition means for acquiring the temperature of the ink;
Thermal head temperature acquisition means for acquiring the temperature of the thermal head;
Calculating means for calculating a temperature difference between the temperature of the thermal head and the temperature of the ink;
The idling operation of rotating the drum in a state where the confidential master that is not heated and punched by the thermal head is fixed on the outer peripheral surface of the drum, the temperature difference calculated by the calculating means is equal to or greater than a predetermined threshold value If it is, the idling control means to be executed more than when the temperature difference is less than a predetermined threshold;
A stencil printing apparatus comprising:

Images