JP2002079646A - Method and apparatus for plate-making - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the quality of perforations uniform irrespective of the quality of the surface of a stencil in a mimeographic printing apparatus having a plate- making device. SOLUTION: A master surface sensor 300 comprising an emission element 301 and a light receiving element 302 is installed between the stencil roll 22 of a plate-making writing part 20 and a platen roller 24, and the surface state of the stencil 23 is detected optically and automatically. The signal value S1 of the light receiving element 302 is compared with a predetermined standard value. When a reflectance is higher than the standard value, the stencil is judged to be high in quality, and when it is lower than the standard value, the stencil is judged to be low in quality. During high quality, a speed priority mode is set automatically, and plate-making quality is maintained at a certain level or above while perforation is done at a high voltage for a short time. During low quality, an image quality priority mode is set automatically, a plate-making speed is lowered, the perforation is done at a low voltage for a long time, a perforation diameter is made approximately constant, and defective perforation is controlled, so that perforation quality is secured to be similar to that when the quality of the surface of the stencil is high in quality.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for making a perforated plate by forming perforations in a stencil sheet using a thermal head, and more particularly to improving perforation quality.

[0002]

2. Description of the Related Art Conventionally, a stencil printing machine used for stencil printing includes a thermal head in which a number of heating elements are arranged and a thermoplastic resin film (hereinafter simply referred to as a stencil sheet). In a state in which the heating elements are pressed against each other, power is supplied to each heating element based on image information to drive the heating elements to generate heat, and the arrangement direction of the heating elements is set as a main scanning direction. There is known a method in which a thermal head and a stencil sheet are relatively moved in a sub-scanning direction orthogonal to a scanning direction to form a hole in the stencil sheet carrying one sheet of image information.

When one pixel is perforated in such a plate making apparatus, a constant applied voltage calculated from an average resistance value of all the heating elements constituting the thermal head and a target power is continuously applied for a predetermined time. Is generally applied to the heating element, and at this time, the applied voltage output from the power supply circuit is generally set so as to attain the target power.

[0004]

However, even if the applied voltage is set so as to attain a predetermined target power, the surface state of the stencil sheet to be perforated is deteriorated or deteriorated, for example, with irregularities on the surface. The perforation diameter varies, and the perforation performance is reduced. As a result, image defects such as white spots occur in the printed matter.

[0005] In addition, stencil paper is manufactured by adhering a film and a support (mainly Japanese paper) with an adhesive. However, even when the applied amount of the adhesive is too large or when the applied amount varies. The perforation diameter varies and the perforation performance decreases.

In other words, even if the applied voltage is set so as to have a predetermined target power, the stencil sheet has irregularities on the surface of the stencil sheet, that is, the quality of the surface state (smoothness of the film surface) and the amount of the adhesive applied. There is a problem that the perforated diameter varies depending on factors that affect the quality of the base paper.

Further, even when the target power is constant, that is, when the total amount of heat generated is constant, there is no variation in the perforated diameter in each quality state of the stencil sheet, but the perforated diameter is low at high quality and at high quality. In some cases, resulting in a difference in printing performance.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a stencil making method and apparatus which can perform perforation with substantially the same quality regardless of the quality of the stencil sheet. is there.

[0009]

According to the investigation by the present inventor, even when the total heat generation energy, which is the product of the power for drilling and the supply time of the power for drilling, is substantially the same, the plate making speed is increased. Shortening the supply time of the perforating power to each heating element when perforating one pixel in each main scan tends to cause variation in the perforation diameter, while conversely reducing the plate making speed, that is, reducing the perforating power. The longer the supply time, the more difficult it is for the perforation diameter to vary. In other words, the lower the plate making speed, the higher the perforation S / N ratio, and the lower the quality of the stencil paper, which has irregularities. However, it was found that a substantially constant perforation diameter can be formed by reducing the plate making speed and increasing the supply time of the perforation power. The present invention has been made based on such findings.

That is, according to the plate making method of the present invention, perforation power is supplied for a predetermined time to each heating element of a thermal head in which a large number of heating elements each corresponding to a pixel are arranged in the main scanning direction. In a stencil making method in which a stencil sheet is perforated to make a stencil sheet by relatively moving the stencil sheet in a sub-scanning direction substantially orthogonal to the main scanning direction while the stencil sheet is pressed against the thermal head, the quality of the stencil sheet is And adjusting at least one of the magnitude of the power for drilling and the supply time of the power for drilling.

In the stencil making method of the present invention, it is desirable that the above adjustment be made according to the quality of the surface condition of the stencil sheet, or that the adjustment be made in a direction in which the perforation quality is homogenized.

Although "according to the quality of the surface condition of the stencil paper" is described, the information on the quality of the surface condition of the stencil paper can be determined, for example, by a user by visually judging the film side surface of the stencil paper or by using a predetermined inspection device. The stencil sheet may be obtained by performing a quality inspection or the like, or may be obtained by indirectly judging the quality of the surface state of the stencil sheet from a print result of test printing or the like.

Alternatively, the quality of the surface state of the stencil sheet, that is, the smoothness (degree of irregularity) of the film-side surface may be obtained by optically detecting using a photosensor or the like.

If the light transmittance of the stencil paper is detected by using a photo sensor or the like, the quality of the stencil paper other than the "quality of the surface state" such as the amount of adhesive applied can be optically detected. Can be.

When performing the adjustment in a direction in which the drilling quality is homogenized, it is preferable to adjust both the magnitude of the drilling power and the supply time of the drilling power.
This is because the same perforation diameter is formed irrespective of the plate making speed by making the total heat generation amount, which is the product of the size of the drilling power and the supply time of the drilling power, substantially constant regardless of the plate making time. This is to make it possible.

When the quality of the stencil sheet is low, the effect of low-speed stencil making to improve the perforation quality by reducing the power for perforation and extending the supply time is greater when the quality of the stencil sheet is high. There are few advantages of low-speed stencil making.On the other hand, the disadvantage of spending more time on stencil making is greater. Therefore, it is preferable to perform low-speed plate making only at low quality and high-speed plate making at high quality.

Therefore, in the stencil making method of the present invention, when the quality of the surface condition of the stencil sheet is low, the power for perforation is reduced and the supply time is lengthened as compared with when the quality is high, and the quality of the surface condition of the stencil sheet is reduced. When the power is high, it is desirable to increase the drilling power and to shorten the supply time as compared to when the power is low.

In order to maintain the roundness of the perforation diameter regardless of the adjustment of the perforation power supply time, when the perforation power supply time is increased, the conveying speed of the stencil sheet in the sub-scanning direction is reduced. Conversely, when shortening the supply time, it is desirable to adjust the transport speed of the stencil sheet according to the supply time of the perforating power, such as increasing the transport speed.

On the other hand, when the total heat energy is constant and the stencil sheet is of low quality, the perforation diameter is smaller than when the stencil sheet is of high quality. The perforation diameter becomes large, that is, in each quality state, there is no variation in the perforation diameter, but there is a difference in the perforation diameter between the low quality time and the high quality time, as a result,
In some cases, a difference occurs in printing performance. In such a case, by adjusting at least one of the magnitude of the power for perforation and the power for perforation, when the stencil sheet is of low quality, the total amount of heat generation is increased so that the perforation diameter becomes larger, When the stencil sheet is of high quality, the total heat generation energy may be reduced so that the perforated diameter becomes smaller.

Further, when the quality of the stencil sheet is low, the line cycle in the sub-scanning direction may be longer than when the quality is high.

The plate making apparatus of the present invention is an apparatus for performing the above plate making method, that is, a thermal head in which a large number of heating elements each corresponding to a pixel are arranged in the main scanning direction, and a power for punching for each main scanning. Energy supply means for supplying to each heating element for a predetermined time, and sub-scanning means for relatively moving the stencil sheet in a sub-scanning direction substantially orthogonal to the main scanning direction while the stencil sheet is pressed against the thermal head, In a stencil making apparatus for making a stencil by perforating a stencil sheet, the stencil sheet is provided with an adjusting means for adjusting at least one of the magnitude of the perforation power and the supply time of the perforation power according to the quality of the stencil sheet. It is characterized by the following.

In the stencil making machine of the present invention, it is preferable that the adjusting means performs the adjustment according to the quality of the surface condition of the stencil sheet.

In the plate making apparatus of the present invention, it is preferable that the adjusting means performs the adjustment in a direction in which the perforation quality is homogenized.

In the stencil making machine of the present invention, when the quality of the stencil sheet is low, the power for perforation is made smaller and the supply time is made longer than when the quality of the stencil sheet is high. It is desirable to increase the power for drilling and to shorten the supply time as compared with the case.

The means for acquiring the information on the quality of the stencil may be a means for inputting the result of the user's judgment on the quality of the stencil, or the quality of the stencil (for example, whether the surface is uneven or not. The amount of adhesive applied may be automatically detected. In the latter case, it is desirable to have a detecting means for optically and automatically detecting information on the quality of the stencil sheet.

Further, the adjusting means may extend the line cycle in the sub-scanning direction when the quality of the stencil sheet is low compared to when the quality is high.

[0027]

According to the plate making method and apparatus of the present invention,
Since at least one of the size of the perforating power and the supply time of the perforating power is adjusted according to the quality of the stencil paper such as the unevenness of the surface of the stencil paper and the amount of the adhesive applied, the stencil paper is used. It is possible to perform plate making in which the diameter of the perforations is made substantially constant and the occurrence of perforation defects is suppressed without being affected by the quality of the perforation. In other words, high perforation quality can always be ensured, and there is no risk of image defects such as white spots on printed matter.

Further, when the quality of the stencil sheet is low, the power for perforation is made longer by making the power for perforation smaller than when it is high, and conversely, when the quality of the stencil paper is high, the power for perforation is made longer when it is low and the supply time becomes longer. If the quality of the stencil sheet is low, the effect of maintaining a predetermined perforation quality as a low-speed stencil can be enjoyed when the quality of the stencil paper is low, while the high-speed stencil can be performed while maintaining the predetermined perforation quality when the quality is high. It is possible to provide a practical plate making method and apparatus which can provide a substantially uniform diameter of a perforation with no variation in any quality, and does not cause a problem that it takes a long perforation time when the surface condition is high quality.

When the quality of the stencil sheet is low, the line cycle in the sub-scanning direction is made longer than when the quality of the stencil sheet is high. And the quality of perforation is improved.

Further, the present invention can be carried out without bothering the user by automatically and optically detecting information on the quality of the stencil sheet.

[0031]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a side sectional view of a stencil printing apparatus to which an embodiment of the plate making apparatus of the present invention is applied,
FIG. 2 is a plan view showing an outline of an operation panel provided on the upper surface of the stencil printing apparatus.

This stencil printing apparatus uses a thermal head 21 as an output head for stencil making. A stencil reading unit 10, a stencil making unit 20, a cutter unit 30, and a printing unit 40 as a stencil making device of the present invention. It is composed of

The plate-making reading section 10 reads the original 1
3 and a document setting table 12
Document sensor 17 for detecting document 13 set on top
And a reading motor 18 receiving a detection signal of the original sensor 17
A document feed roller pair 14 driven to rotate, a contact type line image sensor 11 that optically reads an image of the fed document 13 and converts it into an electric signal, and a document 13 read by the line image sensor 11. And a document discharge roller pair 15 which is driven to rotate by a reading motor 18 such as a stepping motor for discharging the document onto a document discharge tray 19. A document IN sensor 16 is provided downstream of the document conveying roller pair 14 to detect the conveyed document 13 and determine the start of a process of the plate making writing unit 20 described later.

The stencil writing section 20 includes four head blocks 21a to 21 each having a plurality of heating elements 21Z.
d), and a stencil sheet (master) 23 sent out from a stencil sheet roll 22.
Motor 2 composed of a stepping motor or the like that conveys the film while pressing the film surface side against the thermal head 21
5, a stencil sheet 23 produced by the thermal head 21 and a stencil sheet transported by a write motor 25 for transporting the stencil sheet 23 to a clamp portion 32 of a drum (plate cylinder) 33 described later. And a roller pair 26. The platen roller 24, the writing motor 25, and the pair of stencil conveying rollers 26 constitute the sub-scanning means of the present invention.

Between the stencil paper roll 22 of the stencil writing section 20 and the platen roller 24 (thermal head 21), a stencil paper 23 as a stencil information acquiring means for optically automatically detecting the surface state of the stencil paper 23 on the film surface side. Master surface sensor 30
0 is provided.

The cutter section 30 has a cutter 31 for cutting the stencil sheet 23 when the stencil sheet 23 produced by the thermal head 21 has a predetermined length wound around the drum 33. .

The printing section 40 is loaded on a drum 33 having an ink supply section for supplying a fixed amount of ink to the inner surface thereof by an ink reservoir 48 formed between a doctor roller 46 and a squeegee roller 47, and on a paper feed table 44. A pick-up roller 46 that picks up and conveys the printing paper 43 one by one from the printed printing paper stack,
6, a timing roller 42 for sending out the printing paper 43 conveyed from 6 at a predetermined timing, a press roller 35 for pressing the printing paper 43 sent out from the timing roller 42 to the conveying path 41 against the outer peripheral surface of the drum 33,
The print paper 43 includes a separation claw 39 for peeling off the printed printing paper 43 from the drum 33 and a discharge tray 49 for discharging and loading the printing paper 43 peeled off from the drum 33.

A thermal head 2 is provided on the outer peripheral surface of the drum 33.
1 is provided with a clamp portion 32 for clamping the leading end of the stencil sheet 23 made and transported by the stencil 1. After the clamping, the stencil sheet 23 having been made stencil is rotated by rotating a drum 33 by a main motor 34. Wrapped around the surface.

The top of the stencil printing machine is shown in FIG.
As shown in FIG. 1, an operation panel 400 having a display panel 401 composed of an LCD or the like and an operation key group 402 is provided, and the user operates the operation key group while referring to various information displayed on the screen of the display panel 401. Any of the keys 302 can be operated.

An operation key group 402 includes a plate making start key,
Operation keys provided in a normal stencil printing apparatus, such as a print start key, a print mode setting key, a numeric keypad 402a used for inputting the number of prints, a reset key, and a job emergency stop key are provided.

FIG. 3 is a circuit diagram showing details of the thermal head 21, FIG. 4 is a block diagram showing an outline of a control circuit system of the stencil printing unit 20 of the stencil printing apparatus having the above-described configuration, and FIG. FIG. 6 is a timing chart showing the timing at which one block of the head 21 is driven to generate heat, and FIG. 6 is a timing chart showing the timing at which the entire thermal head (all blocks) is driven to generate heat.

As shown in FIG. 3, the thermal head 21 has 4096 heating elements 21Z, and in order to suppress power consumption, four blocks (21a to 21d) are provided for each of the 1024 heating elements 21Z. Each block is driven by the head control circuit 100 to generate heat in a time-division manner (1 to 4096 in FIG. 3 indicate heating element numbers corresponding to pixels).

As shown in FIG. 4, a control circuit system for making a stencil sheet 23 using the thermal head 21 is provided with a system control microcomputer 410 which controls the entire apparatus and functions as adjusting means of the present invention. ,
The microcomputer 410 includes a power supply circuit 140, a head control signal generation circuit 160, and a print data generation circuit 17.
0, a head control circuit 100 functioning as an energy supply means of the present invention, an operation panel 400, a plate making / reading unit 10, a motor controller 28 for rotatingly driving a writing motor 25, and a master surface sensor 300 are connected. Have been. From the system control microcomputer 410, command signals C1,...
C6 is output.

When the original 13 is set on the original platen 12 and its leading end is brought into contact with the original conveying roller pair 14, the original sensor 17 detects the original 13 and displays on the display panel 401 that the plate making operation is possible. .

When the plate-making start key is depressed while the printing paper 43 of a predetermined size is set on the paper feed table 44, the size of the printing paper 43 is detected by a copy object size detecting means (not shown) and the display panel 401 is displayed.
The information is displayed on the upper side, and the original conveying roller pair 14 is rotated by the driving of the reading motor 18 to start the original feeding. Subsequently, when the document IN sensor 16 detects that the document 13 has been conveyed, and then sends the document 13 by a predetermined length, the stencil sheet 23 is conveyed by the drive of the platen roller 24 and the stencil sheet feeding is started.

Simultaneously with the start of feeding of the base paper, the plate making reading section 1
The image of the document 13 of a predetermined size is optically read by the document 13 by the 0 line image sensor 11.
The multi-valued data obtained by reading the original 13 is input to an image processing circuit (not shown), converted into binary data, input to the print data generation circuit 170 of the head control circuit 100, and based on a command from the microcomputer 410, The serial print data DAT1 to DAT4 output to the blocks 21a to 21d of the thermal head 21 are output to the thermal head 21.

In parallel with the image reading, in the head control signal generation circuit 160, based on a command from the microcomputer 410, the clocks CLK1 to CLK4 for outputting the print data DAT1 to DAT4 to each heating element 21Z, Latch data / LAT1-4 for converting the print data DAT1-4 of the thermal head 21 into parallel signals and holding them, and heat signals (enable signals, strobe signals / STB) / applied to the heat elements 21Z of each block of the thermal head 21 / ENL1 to ENL4 are created, and these various control signals are output to the thermal head 21.

The thermal head 21 is provided with an output circuit 72 as shown in FIG. The output circuit 72 outputs the print data DAT1 to DAT4 input from the head control circuit 100.
, Latch signal / LAT 1-4, enable signal / ENL 1-4,
Using the four signals CLK1 to CLK4, the heating elements 21Z of each of the divided blocks of the thermal head 21 are driven to generate heat in a time-division manner.

That is, the serial print data DAT1 to DAT4 input to the thermal head 21 are converted into parallel data by a 1024-bit serial input shift register 75, and latched by latch signals / LAT1 to LAT4 generated at a predetermined timing. 76. A predetermined applied voltage Vh supplied from the power supply circuit 140 is applied to one end of each heating element 21Z, and a result of a logical product of the input enable signals / ENL1 to 4 and the data held in the latch 76 is generated. The heating element 21Z is driven to generate heat at a desired timing by being input to the other end of the element 21Z.

As described above, a perforated image is formed on the stencil sheet 23, that is, stencil making is performed on the basis of the data obtained by reading the original 13, and thereafter, when a predetermined platen feed amount is fed, the stencil sheet feed is performed. When the document 13 is discharged and then the document 13 is discharged, the document feeding is stopped. Further, the stencil sheet 23 after the stencil printing is conveyed by a fixed amount by the document conveying roller pair 26, and one end of the stencil sheet 23 is fixed at the clamp section 32. After that, the stencil sheet 23 is wound around the outer peripheral surface of the drum 33 by rotating the drum 33, wound by a predetermined amount, and then cut by the cutter 31. As a result, the stencil sheet 23 is completely wound around the outer peripheral surface of the drum 33, and the printing operation is on standby.

Next, when the number of prints is input using the ten keys 402a, the data is displayed on the display panel 401. When the print start key is pressed in this state, the printing paper 43 is conveyed one by one to the timing roller 42 by the pickup roller 46, and after the primary standby, the timing roller 42 is driven at a predetermined timing when the drum 33 rotates. It is sent to the transport path 41. Transport path 4
The printing paper 43 fed into 1 is pressed against the outer peripheral surface of the drum 33 by the press roller 35, and the ink that has passed through the perforated image formed on the stencil sheet 23 is transferred to perform printing. The printing paper 43 on which printing has been performed is
The sheet 9 is peeled off from the outer peripheral surface of the drum 33, conveyed in the direction of arrow Z, and discharged to the sheet discharge table 49.

Here, in the heating driving of this embodiment, as described in, for example, JP-A-60-161163 and JP-A-2-8065, image quality deterioration caused by the heating history of the heating element 21Z is eliminated. Therefore, the past heating history of each heating element 21Z or its surrounding heating element 21Z is stored in a line memory such as a RAM, and the appropriate applied energy of the heating element 21Z of the current line is calculated based on the heating history. Then, a so-called “heat history control” correction method for controlling the amount of heat generated by the heating element 21 </ b> Z to make the image uniform is used. Here, the print data for thermal history control is particularly referred to as history data to distinguish it from the raw data of the current line, and the raw data and the history data are collectively referred to as print data.

There are various methods for generating the history data which is the print data for the heat history control. For example, the logical data is obtained by taking the logical product of the data obtained by inverting the previous line data and the raw data of the current line. can get.

Then, as shown in FIG. 5A, the generated history data is input to the output circuit 72 for each line (main scan). The output circuit 72 is based on various control signals such as a latch signal from the head control signal generation circuit 160, and is connected to the heating element 21Z connected to the output circuit 72.
Is driven in a time-division manner for each block (21a to 21d). When the heating drive according to the history data is completed, the output circuit 72 continues to output the print data generation circuit 1.
Raw data of the current line is input from 70, and the heating element 21Z is driven to generate heat in accordance with the raw data. And FIG.
As shown in (1), such an operation is similarly performed for each block in a time-division manner. Note that, as shown in FIG. 5B, heat generation may be performed based on raw data of the current line first, and then heat generation may be performed based on history data.

Thus, if the raw data of the current line has generated heat, and if the previous line whose pixel position in the main scanning direction has the same position has generated heat, the heating drive based on the history data is not performed. Conversely, if there is no heat generation in the previous line, heat generation is performed based on the history data.
When combined with the heat generation based on the raw data of the current line, the heat generation time becomes shorter when the previous line generates heat, and conversely, the heat generation time becomes longer when there is no heat generation in the previous line. That is, as heat history control of this device, if the history data and the raw data of the current line are sequentially transferred to the output circuit 72 during one line, and the heating element 21Z generates heat twice, the heat generation time becomes longer, Control is performed such that the heat generation time is shortened if heat is generated only once. If the heating is not performed twice, that portion becomes a non-printing pixel.
In the following, the time for generating heat by heat history control for both times is long ST
B: The time during which heat is generated only once is called a short STB.

FIG. 7 shows the relationship between the plate making speed and the perforating S / N ratio. Note that the perforation S / N ratio is an average opening area X,
When the opening area standard deviation Y is defined as “perforation S / N ratio = 10
log (X2 / Y2).

As shown in the figure, when the total heat energy, which is the product of the drilling power defined by the voltage applied to both ends of the heating element 21Z and the resistance of the heating element 21Z, and the supply time of the drilling power, is substantially equal. It was found that the perforation S / N ratio increased as the stencil speed decreased, regardless of the quality of the stencil sheet 23.

In the apparatus having the above configuration, based on such characteristics, when the surface condition of the stencil sheet 23 is of relatively low quality, the power for perforation, in other words, the applied voltage is made relatively small and the power for perforation ( When the surface state of the stencil sheet 23 is of relatively high quality, the power for perforation (applied voltage) is made relatively large and the power for this perforation (applied voltage) is supplied. Try to keep the time relatively short. This will be specifically described below.

In order to optically automatically detect the surface state of the stencil sheet 23, the light emitting element 301 and the light receiving element are provided between the stencil sheet roll 22 and the platen roller 24 of the stencil writing section 20, as described above. A master surface sensor 300, which is a reflective photosensor consisting of 302, is provided.

The light emitting element 301 emits light L having a predetermined wavelength toward the stencil sheet 23 in response to a command signal C6 from the microcomputer 410. This light L is reflected by the film surface of the stencil sheet 23 and enters the light receiving element 302. The intensity of the light incident on the light receiving element 302 depends on the glossiness indicating the smoothness of the surface (film) of the stencil sheet 23, in other words, the reflectance.

In the above stencil printing apparatus, several types of stencils having different prices can be mounted. Here, when the factor which deteriorates the degree of unevenness of the base paper surface (the smoothness of the film surface), which is one of the causes of variation in the perforated diameter, was examined, the following was found.

First, stencil paper is produced by laminating a film and a support such as Japanese paper with an adhesive. The stencil paper is laminated with a constant tension so as not to cause wrinkles. At this time, a base paper having a high surface smoothness (good) can be produced if the two elastic moduli are the same, but if the elastic moduli are different, the surface smoothness becomes low.

Second, the base paper is wound up into a roll by laminating. When the base paper is wound up in a roll, the Japanese paper overlaps with a certain pressure on the film surface. As a result, the unevenness of the Japanese paper is reflected on the film surface, and the smoothness of the surface of the film surface is reduced as a whole. The degree of smoothness at this time also differs depending on the density and the material of the Japanese paper.

For example, if one type of film and several types of Japanese paper are used, the elastic modulus, density,
Base paper with good surface condition (good smoothness) or bad base paper is produced according to the difference of the material. In reality, none of the three factors of elastic modulus, density, and material are good or bad Japanese paper, but base paper with high gloss (reflectance), that is, good smoothness, is of high quality. The higher the price and the lower the gloss, the lower the quality and the lower the price.

On the other hand, when the smoothness of the surface of the stencil sheet is reduced, even if the stencil sheet is pressed against the thermal head at a constant pressure, one micro-heating element (resistor) of the thermal head and the film of the stencil sheet are viewed microscopically. Since a portion having poor adhesion to the surface appears, heat energy of the heating element hardly reaches the film surface of the base paper in this portion, and the perforation quality is deteriorated.

A user who values the normal image quality may consider using a high-priced high-quality stencil sheet, that is, a stencil sheet having a high gloss (reflectance). Drilling quality can be maintained. On the other hand, when a low-priced low-quality stencil sheet, that is, a stencil sheet with low gloss (reflectance) is used, as can be seen from the characteristics shown in FIG. In order to maintain the perforation quality to a certain degree or more, it is necessary to reduce the plate making speed.

From the above, the signal value (A) of the light receiving element 302 obtained by detecting the glossiness (reflectance) of the stencil sheet 23 is obtained.
/ D converted data) may be compared with a predetermined reference value to determine whether to make plate making with priority on image quality or speed.

Therefore, in the present embodiment, it is preferable to adjust the power for drilling and the supply time based on a flowchart as shown in FIG. That is, first, the master surface sensor 3
00, the gloss (reflectance) of the stencil sheet 23 is detected. The signal value S1 of the light receiving element 302 obtained by this detection
(Or data after A / D conversion) may be compared with a predetermined reference value. If the reflectance of the stencil sheet 23 is higher than the reference value, it is determined that the stencil sheet 23 is of high quality. Is lower than the reference value, it is determined that the quality is low (ST1).
1).

When the reflectance of the stencil sheet 23 is high and the quality is high, the speed priority mode is automatically set, and the perforation quality is maintained at a certain level or more while the stencil speed is set high (ST12-speed priority mode). , ST13). On the other hand, when the reflectance of the stencil sheet 23 is low and the quality is low, the image quality priority mode is automatically set to reduce the stencil making speed (ST12-image quality priority mode, ST14). Then, plate making is performed in the set plate making mode, and thereafter printing is performed (ST15).

When the next original 13 is present, the process returns to step 11 (ST11) to perform the same processing as above (ST16-YES), and when there is no next original 13, the processing is terminated (ST16-NO).

To reduce the plate making speed in order to improve the perforation quality, as shown in FIG. 9, extending the line period LST, long STB and short STB, which is the plate making time for one main scan, is performed. This means extending the heat generation time of each heating element 21Z, but simply increasing the heat generation time (reducing the plate making speed) also increases the total heat generation energy,
The perforation quality is not always favorable. Therefore, even if the heating time is changed (the plate making speed is changed), the total heating value is reduced even if the heating time is changed (the plate making speed is changed), for example, by reducing the voltage applied to the heating element 21Z so that the total heating energy is not increased even if the heating time is extended. Microcomputer 4 so that no change occurs
The application voltage Vh output from the power supply circuit 140 is adjusted by the command signal C1 from the power supply circuit 140. That is, when the speed priority mode is set, in step 13 (ST13), the perforation power corresponding to the applied voltage is relatively large, and the supply time is relatively short. In (ST14), low-voltage long-time drilling is performed in which the power for drilling is relatively small and the supply time is relatively long.

Further, when the supply time of the perforating power is adjusted while the conveying speed of the stencil sheet 23 in the sub-scanning direction Y is kept constant, the perforation width in the main scanning direction and the perforation width in the sub-scanning direction do not become the same. It becomes difficult to maintain the roundness of the hole diameter.
Further, the perforation resolution in the sub-scanning direction differs according to the supply time. Therefore, in order to maintain the circularity of the perforation diameter and to keep the perforation resolution in the sub-scanning direction constant, regardless of the adjustment of the perforation power supply time, when the perforation power supply time is extended, Sub scanning direction Y
The transport speed V of the stencil sheet 23 is adjusted according to the supply time of the perforating power, for example, by increasing the transport speed V when shortening the supply speed V and shortening the supply time. This adjustment is performed by the microcomputer 4 so that the product of the transport speed V and the line cycle LST corresponding to the supply time of the drilling power is constant.
Motor controller 28 according to command signal C4 from
To control the rotational drive of the writing motor 25, thereby controlling the rotational speeds of the platen roller 24 and the pair of paper transport rollers 26.

FIG. 10 shows the result (perforated state) of stencil making in the stencil printing apparatus having the above configuration and a conventional example. FIG.
As shown in FIG. 0 (A), in the conventional example, the line period LST is 2.0 msec, the length STB is 500 μsec,
When a solid image is perforated on a normal stencil sheet (high-quality stencil sheet) with the perforation power set to 0.068 W, a substantially uniform perforation diameter is formed. When a solid image is perforated on a low-quality base paper), the perforation diameter becomes uneven, and a white point or the like is generated in a printing result.

On the other hand, using the same thermal head, as shown in FIG. 10B, the plate making conditions were set such that the line cycle LST was 3.0 msec, the long STB was 750 μsec,
When the power for perforation is changed to be 0.058 W and a solid image is perforated on deteriorated stencil paper (low quality base paper),
As in the case of ordinary stencil paper, a substantially uniform perforation diameter can be formed. In addition, by adjusting the transport speed V of the stencil sheet 23 in accordance with the adjustment of the line cycle LST, it is possible to maintain the perforation diameter substantially in a perfect circle and to make the perforation resolution in the sub-scanning direction constant.

As described above, according to the apparatus having the above-described configuration, if the surface state of the stencil sheet 23 is automatically detected by the sensor 300 and the stencil making mode is automatically set, a certain level of perforation quality can be obtained regardless of the surface state of the stencil sheet 23. Can be maintained. As a result, for example, the stencil sheet 2 whose surface unevenness is severely deteriorated by prolonging the heat generation time of the perforation and lowering the applied power is used.
3, the heat energy can be sufficiently transmitted to the stencil 3, so that a stencil making can be performed with the same perforation size as in the case of using a high-quality stencil sheet and capable of reducing image defects such as white spots as much as possible. it can.

Further, when the image quality priority mode is set, the line cycle is lengthened compared to the case where the speed priority mode is set. Sufficient securing can be achieved, and the quality of perforation can be further improved.

In the above embodiment, the stencil sheet 23 is automatically detected by the master surface sensor 300 to automatically set the stencil mode. However, the stencil sheet 23 can be manually set by the user. For example, when a sensor for automatic detection is not provided, the user may determine the surface condition of the stencil sheet 23 and set the stencil mode.

Since the deterioration of the surface of the stencil sheet 23 directly affects the image quality of the printed image, when the user performs manual setting, the quality of the surface state of the stencil sheet 23 is indirectly checked by checking the printed matter. May be determined.

FIG. 11 is a flowchart showing the operation when the surface state of the stencil sheet 23 is determined based on the user's judgment. The only difference from FIG. 8 is that step 11 ′ (ST11 ′) for manual input by the user is provided instead of step 11 (ST11) for automatically setting the plate making mode by the master surface sensor 300. . In the case where such manual setting is performed, a plate making mode setting key capable of manually selecting either the punching quality priority or the plate making speed priority may be provided in the operation key group 402 shown in FIG. .

In the above embodiment, each time the original 13 is supplied, the surface state of the stencil sheet 23 is determined by the master surface sensor 3.
00, but in terms of detecting a difference in quality according to the type of the stencil sheet 23, it is detected in units of the stencil sheet roll 22, that is, only when the stencil sheet roll 22 is made for the first time. The state may be detected and the result may be applied to subsequent plate making.

Further, the stencil sheet wound up in a roll form cannot be wound well unless a strong tension is applied at the beginning of the winding. The smoothness of the surface becomes worse nearer. In other words, not only the type of base paper is different, but the smoothness changes even within one base paper.
In other words, the smoothness of the surface of the stencil sheet wound up in a roll shape deteriorates with time. in this case,
If the surface state of the stencil sheet 23 is detected by the master surface sensor 300 each time the document 13 is supplied, it is possible to cope with a temporal change in the surface quality of one stencil sheet.

In this case, if the surface state is detected for each main scan of perforation, it is possible to cope with a change in the smoothness of the stencil sheet in the perforation process of one document.

Further, in the above embodiment, the signal value S1 of the light receiving element 302 representing the gloss (reflectance) of the stencil sheet 23 detected by the master surface sensor 300 corresponding to the smoothness of the surface of the stencil sheet 23 is set as the reference value. In comparison, when the reflectance is high, it is determined that the surface state of the stencil sheet 23 is of high quality, and when the reflectance is low, it is determined that the quality is low. Was
The light receiving element 3 representing the glossiness of the stencil sheet 23 is not limited thereto.
Stepless (continuous) according to the magnitude of the signal value S1 of 02
Alternatively, the magnitude of the drilling power and the supply time of the drilling power may be adjusted in a number of stages. Thereby, the perforation quality can be more accurately (finely) homogenized.

Further, in the above embodiment, the smoothness of the film surface, that is, the unevenness, as one aspect of the quality of the stencil paper, is considered as a problem. The reason for this is not necessarily limited to the smoothness of the film surface. For example, as described above, in the process of manufacturing a stencil sheet, the film and the support are attached with an adhesive, but the perforation diameter may vary depending on the amount of the applied adhesive. Changes in the amount of adhesive applied include those depending on the density (type) of Japanese paper and those that occur during the manufacturing process. The smaller the amount of application, the better the perforation quality, that is, the less variation in the perforation diameter, and the greater the amount of application, the more difficult it is to open the holes, and the more the perforation diameter varies.
Also, if there is a variation in the application amount itself, the variation in the perforation diameter naturally occurs. On the other hand, the light transmittance of the stencil paper changes according to an increase or decrease in the amount of the adhesive applied, which is one aspect of the quality of the stencil paper. Therefore, by detecting the light transmittance using an optical detection means such as a photo sensor and performing the same control as described above according to the detection result, the perforation quality can be made uniform.

Further, in the above embodiment, the diameter of the perforations is made uniform (without variation) while keeping the total heat generation energy constant, but the quality of the stencil sheet and the perforation quality are In each quality state of the base paper, there is no variation in the perforation diameter, but there is a difference in the perforation diameter between low quality and high quality, and as a result, a difference in printing performance may occur. In such a case, by adjusting at least one of the magnitude of the power for perforation and the supply time of the power for perforation, when the stencil sheet is of low quality, the total heat generation energy is increased so that the perforation diameter is smaller than in the past. The size of the perforated paper may be larger than that of the case where the present invention is not applied, and when the stencil sheet is of high quality, the total amount of heat generated may be smaller than in the conventional case, so that the perforated diameter is smaller. This makes it possible to maintain a constant perforation quality and printing quality regardless of the quality of the stencil sheet.

In the conventional plate making method and apparatus, the total amount of heat generated is determined according to the average resistance value and the target power of all the heat generating elements constituting the thermal head and the quality of the stencil sheet assumed in advance. In the case where the quality of the base paper is different from what was originally assumed, the total heat generation amount cannot be controlled. On the other hand, in the present embodiment, the total heat generation amount is controlled in accordance with the quality of the stencil base paper and the perforation diameter is controlled. By adjusting, the perforation quality and the printing quality can be kept constant irrespective of the quality of the stencil sheet, so that the present embodiment has a great effect.

As another embodiment of the present invention, when the image quality priority mode is set, low-voltage long-time drilling is not performed, but the same as the drilling power applied in the speed priority mode. It is also conceivable that the power is applied for a longer time than the application time in the speed priority mode. In such a stencil printing apparatus, the result (perforated state) of stencil making using the same thermal head as in the embodiment is shown in FIG.
Shown in

As shown in FIG. 12A, the plate making conditions were as follows: the line cycle LST was 3.0 msec and the length STB was 600 μm.
When the solid image is perforated on the deteriorated stencil sheet (low-quality stencil sheet) in a state where the power for perforation is set to 0.068 W,
A relatively uniform perforation diameter can be formed as in the case of using a normal stencil sheet. Although the quality of the perforation shown in FIG. 12A is slightly lower than the quality of the perforation shown in FIG. 10B, when switching between the speed priority mode and the image quality priority mode, the value of the power for perforation is changed. Since there is no need to change, the circuit configuration of the stencil printing apparatus can be simplified.

According to still another embodiment of the present invention, when the image quality priority mode is set, rather than performing low-voltage long-time drilling, a power larger than the drilling power applied in the speed priority mode is used. Alternatively, the application may be performed for the same time as the application time in the speed priority mode. As shown in FIG. 12B, the plate making conditions were set such that the line cycle LST was 3.0 ms.
ec, the length STB is 500 μsec, and the drilling power is 0.0
Degraded stencil paper (low quality stencil) at 75W
When a solid image is perforated, a relatively uniform perforation diameter can be formed as in the case of using a normal stencil sheet.
The quality of the perforation shown in FIG. 12B is slightly lower than the quality of the perforation shown in FIG. 10B, but when switching between the speed priority mode and the image quality priority mode, the application time (long STB) Since it is not necessary to change the configuration, the circuit configuration of the stencil printing apparatus can be simplified. The above 2
Also in the other embodiments, by adjusting the transport speed V of the stencil sheet 23 in accordance with the adjustment of the line cycle LST, the diameter of the stencil sheet 23 is maintained substantially in a perfect circle, and the resolution of the piercing in the sub-scanning direction is made constant. Can be.

As described above, the term "quality of stencil sheet" in the present invention includes everything that affects the diameter of the stencil sheet when perforating the stencil sheet and making a stencil. The adjustment of at least one of the magnitude of the drilling power and the supply time of the drilling power according to the degree of the drilling is included in the present invention.

The degree of the "quality of the stencil sheet" may be detected at any timing of one roll of the stencil sheet, one sheet of the original, or one main scan of perforation. Needless to say, the more the chances of detecting the “quality of the stencil sheet”, the more finely the perforation quality and printing quality can be adjusted.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a stencil printing machine to which an embodiment of a stencil making machine according to the present invention is applied.

FIG. 2 is a plan view schematically showing an operation panel provided on an upper surface of the stencil printing apparatus shown in FIG.

FIG. 3 is a circuit diagram showing details of a thermal head.

FIG. 4 is a block diagram showing an outline focusing on a control circuit system of a stencil making section of the stencil printing machine shown in FIG. 1;

FIG. 5 is a timing chart showing timing for driving one block of the thermal head shown in FIG. 3 to generate heat.

6 is a timing chart showing the timing of driving the entire thermal head shown in FIG. 3 to generate heat.

FIG. 7 is a diagram showing a relationship between a plate making speed and a punching S / N ratio.

8 is a flowchart showing the operation of the stencil printing machine shown in FIG.

FIG. 9 is a timing chart for explaining a method of adjusting the supply time of drilling power.

FIG. 10 is a diagram showing a plate making result (A) of a conventional example and a plate making result (B) of the present invention.

FIG. 11 is a flowchart showing an operation when the surface state of the stencil sheet is determined based on a user's judgment;

FIG. 12 is a diagram showing plate making results.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 plate making reading section 13 original 20 plate making writing section 21 thermal head 21Z heating element 23 stencil sheet 24 platen roller 25 writing roller 26 sheet conveying roller pair 28 motor controller 30 cutter section 40 printing section 100 head control circuit 140 power supply circuit 160 Head control signal generation circuit 170 Print data generation circuit 300 Sensor surface sensor 301 Light emitting element 302 Light receiving element 400 Operation panel 410 System control microcomputer

Claims (12)

[Claims] 1. A perforation power is supplied for a predetermined time to each heating element of a thermal head in which a number of heating elements each corresponding to a pixel are arranged in a main scanning direction for each main scanning, and a stencil sheet is formed. In a stencil making method in which the stencil sheet is perforated by making relative movement in a sub-scanning direction substantially orthogonal to the main scanning direction while the stencil sheet is pressed against the thermal head to perform stencil making, And adjusting at least one of the magnitude of the drilling power and the supply time of the drilling power in accordance with the following. 2. The stencil making method according to claim 1, wherein the adjustment is performed according to the quality of the surface condition of the stencil sheet. 3. The method according to claim 1, wherein the adjustment is performed in a direction in which the perforation quality is homogenized. 4. When the quality of the stencil sheet is low, the power for perforation is reduced and the supply time is lengthened as compared to when the quality of the stencil sheet is high. The plate making method according to any one of claims 1 to 3, wherein the adjustment is performed so that the power for drilling is increased and the supply time is shortened. 5. The stencil making method according to claim 1, wherein when the quality of the stencil sheet is low, the line cycle in the sub-scanning direction is made longer than when the quality is high. 6. The stencil making method according to claim 1, wherein the quality of the stencil sheet is optically detected. 7. A thermal head in which a number of heating elements each corresponding to a pixel are arranged in the main scanning direction, and energy supply means for supplying a power for drilling to each of the heating elements for a predetermined time for each main scanning. And a sub-scanning means for relatively moving the stencil sheet in a sub-scanning direction substantially orthogonal to the main scanning direction while the stencil sheet is pressed against the thermal head. A stencil making apparatus, comprising: an adjusting means for adjusting at least one of the magnitude of the piercing power and the supply time of the piercing power according to the quality of the stencil sheet. 8. A stencil making apparatus according to claim 7, wherein said adjusting means performs said adjustment in accordance with the quality of the surface condition of said stencil sheet. 9. The plate making apparatus according to claim 7, wherein the adjusting means performs the adjustment in a direction in which the perforation quality is homogenized. 10. The adjusting means reduces the power for perforation and increases the supply time when the quality of the stencil sheet is low as compared with when the quality of the stencil sheet is high, and is low when the quality of the stencil sheet is high. The plate making apparatus according to any one of claims 7 to 9, wherein the power for perforation is increased and the supply time is shortened as compared to when. 11. The apparatus according to claim 7, wherein the adjusting means increases the line cycle in the sub-scanning direction when the quality of the stencil sheet is low, as compared to when the quality is high.
11. The plate-making apparatus according to any one of items 1 to 10. 12. The apparatus according to claim 1, further comprising a detecting unit for optically detecting information on the quality of the stencil sheet, wherein the adjusting unit performs the adjustment based on a detection result of the detecting unit. A plate making apparatus according to any one of claims 7 to 11.