JP4845298B2 - Stencil printing machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a stencil printing apparatus that performs plate making by piercing a master base paper, and wraps the master that has been made around the outer periphery of a plate cylinder for printing.
[0002]
[Prior art]
Conventionally, in a stencil printing apparatus, an original image is read by a scanner that functions as an image reading unit, a master plate is made by a plotter that functions as a plate making unit corresponding to the read image data, and the outer periphery of a porous and cylindrical plate cylinder is provided. The master is wound, the plate cylinder around which the master is wound, the paper is fed in the tangential direction of the outer peripheral surface of the plate cylinder, and the ink supplied to the inside of the plate cylinder is discharged from the perforated portion of the master. Printing on the fed paper by oozing is performed.
[0003]
In addition, a stencil that does not include an image reading unit, transmits image data created by a personal computer or the like to the plate making unit, and wraps a master created based on the image data around the outer periphery of the plate cylinder to perform printing. There is also a printing device.
[0004]
In a stencil printing apparatus including an image reading unit and a plate making unit, the resolution of the image reading unit and the resolution of the plate making unit may be different. For example, the resolution of the image reading unit is 600 dpi, and the resolution of the plate making unit is 400 dpi. In such a case, a pixel density conversion process is performed between the pixel density of the image reading unit and the pixel density of the plate making unit. In this pixel density conversion process, a resolution conversion coefficient “K (in this case, K = 400/600 = 2/3)” that matches the pixel density of the image reading unit with the pixel density of the plate making unit is obtained, and image reading is performed. The number of pieces of image data read by the scanning unit is multiplied by a resolution conversion coefficient “K”, and a scaling process using a scaling ratio is performed to create plate-making data. The master is made based on the plate making data.
[0005]
In addition, when printing is performed by winding the master made on the outer periphery of the plate cylinder, the master is stretched by pressurization or the like during printing, and the image printed on the paper becomes larger than the image of the original. appear. Therefore, in order to prevent the elongation of the image printed on the paper caused by the elongation of the master at the time of such printing, the plate-making data is created by reducing in advance, and the reduced plate-making data is used as the reduced plate-making data. An invention of making a master on the basis of this is disclosed in JP-A-8-169169.
[0006]
[Problems to be solved by the invention]
[0008]
Taking into account the elongation of the master at the time of printing, in the invention described in JP-A-8-169169 that platemaking master drilled images of reduced size relative to the image to be printed, the reduction ratio It is not specifically disclosed how to determine the above.
[0010]
The purpose of the present invention, when performing a large number of continuously printed, the master with the print is to improve the dimensional reproducibility of the image printed on the paper even if the resulting elongation.
[0011]
[Means for Solving the Problems]
[0017]
According to the first aspect of the present invention, the master corresponding to the image data is made by the plate making unit, the master made by making a plate is wound around the outer periphery of a porous and cylindrical plate cylinder, the sheet is pressed against the outer peripheral surface of the master, and the plate In the stencil printing apparatus in which the ink supplied into the cylinder is oozed from the perforated portion of the master and the image is printed on the paper, the number of printed sheets from one master and the elongation of the master accompanying the printing are increased. A printing unit that is set when the storage unit that stores the image expansion rate equation that indicates the relationship with the amount of image expansion printed on the paper that causes the problem, and the master plate making and printing using the master are performed consecutively. The plate-making data for making the master is corrected based on the image expansion rate formula so that the expansion amount of the image printed on the paper becomes “0” when the number of printed sheets is approximately half the number of sheets. Corrected plate making data To create a and a corrected prepress data creation means.
[0018]
Therefore, even if the master stretches at the time of printing, based on the corrected plate-making data corrected so that the stretch amount of the image printed on the paper becomes “0” when the number of printed sheets is approximately half of the set number of printed sheets. Since the master is plate-making, the dimensional reproducibility of the printed image is most improved when printing the set number of prints.
[0019]
According to a second aspect of the invention, in the stencil printing machine according to claim 1, wherein the image elongation expression, temperature conditions, humidity conditions, various conditions consisting of printing speed conditions, or, depending on the combination of these various conditions A plurality of images are prepared, and at the time of printing, any one of the image expansion rate formulas that meet the conditions at that time is selected to generate corrected plate-making data.
According to a third aspect of the present invention, in the stencil printing apparatus according to the first aspect, a plurality of the image elongation rate formulas are prepared according to temperature conditions, and at the time of each printing, any one of the above-mentioned conditions that matches the conditions at that time The corrected plate-making data was created by selecting the image expansion rate formula.
According to a fourth aspect of the present invention, in the stencil printing apparatus according to the first aspect, a plurality of the image elongation rate formulas are prepared according to humidity conditions, and at the time of each printing, any one of the above-mentioned conditions that meets the conditions at that time The corrected plate-making data was created by selecting the image expansion rate formula.
According to a fifth aspect of the present invention, in the stencil printing apparatus according to the first aspect of the present invention, a plurality of the image elongation rate formulas are prepared according to printing speed conditions, and any one of the conditions at the time of printing is met. The image expansion rate formula is selected to generate corrected plate-making data.
[0020]
Therefore, even when the amount of elongation of the master during printing fluctuates according to various conditions such as temperature conditions, humidity conditions, and printing speed conditions, it is determined at that time from a plurality of image elongation rate formulas prepared according to those various conditions. Since one image elongation rate formula that meets the above conditions is selected and correction is made based on the selected image elongation rate formula to obtain corrected plate-making data, temperature conditions, humidity conditions, printing speed conditions, etc. Even when the amount of elongation of the master during printing varies depending on various conditions, the dimensional reproducibility of the printed image is most improved.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional front view showing the entire structure of the stencil printing apparatus. Since the basic structure of the stencil printing apparatus is well known, the basic structure will be briefly described. This stencil printing apparatus includes an image reading unit 1 that reads an image of a document, and a plate making unit that punches a master base paper by making a heat generating portion of a thermal head generate heat according to image data read by the image reading unit 1 to make a master. 2. A porous and cylindrical plate cylinder 3 that is engraved around the outer periphery of a plate-making master and rotated, a press roller 4 that is intermittently pressed against the outer peripheral surface of the plate cylinder 3, and a used master From the plate discharge unit 5 that is peeled off from the plate cylinder 3 and stored, a paper feed unit 6 on which a large number of sheets are placed and fed one by one, a paper discharge unit 7 from which printed sheets are discharged, and the like It is configured. In this stencil printing apparatus, the resolution of the image reading unit 1 is 600 dpi, and the resolution of the plate making unit 2 is 400 dpi.
[0022]
FIG. 2 is a block diagram showing a control structure of the stencil printing apparatus. In the figure, a control unit 8 is composed of a microcomputer having a ROM and a RAM as storage units, and via an I / O interface (not shown), an operation unit 9, an image reading unit 1, a temperature sensor 10, and a humidity sensor. 11, a plate making unit 2, a plate discharging unit 5, a paper feeding unit 6 and the like are connected.
[0023]
Among the storage units, the ROM has a program for sequence control of the entire print processing process, the number of prints to be printed from one master, and the amount of expansion of the image printed on the paper due to the master elongation accompanying printing An image expansion rate formula indicating the relationship between the The image elongation rate equation is an equation obtained from the graph of FIG. 3 in which the number of printed sheets and the amount of elongation of the image printed on the paper are examined. Here, three equations corresponding to the temperature condition and the humidity condition are registered. ing. The first image elongation rate equation is under the conditions of a temperature of 30 ° C. and a humidity of 90%, and the second image elongation rate equation is under the conditions of a temperature of 23 ° C. and a humidity of 65%. The image elongation rate equation is for a temperature of 10 ° C. and a humidity of 20%. From the graph of FIG. 3, it can be seen that the image printed on the paper increases as the number of printed sheets increases, and further, the expansion rate varies depending on the temperature and humidity conditions.
[0024]
The operation unit 9 includes a print number setting key for setting the number of prints, a print speed setting key for setting the print speed, a scaling factor setting key for setting a scaling factor at the time of master plate making, image reading of a document, master plate making A start key for starting a series of printing operations such as printing is provided.
[0025]
The image reading unit 1 includes an image reading element such as a CCD (not shown), and inputs the read image data to the control unit 8 after A / D conversion.
[0026]
FIG. 4 is a flowchart for explaining master plate-making processing. After an original is set in the image reading unit 1 and the number of prints, printing speed, variable magnification, etc. are set, the start key is turned on to perform image reading (step S1). The data is A / D converted and then input to the control unit 8 (step S2).
[0027]
The input image data is multiplied by the reciprocal of the resolution conversion coefficient “K = 400/600 = 2/3” for matching the pixel density of the image reading unit 1 with the pixel density of the plate making unit 2 to the number of image data. image data of the virtual is created by (step S3), and the plate making data to be used in the plate making unit 2 is Ru is created by scaling the process variable magnification image data of the virtual this (= display magnification) ( Step S4) . Here, assuming that the number of input image data is 100 and the scaling ratio is 100%, the number of virtual image data created by multiplying the reciprocal “1 / K” of the resolution conversion coefficient is 100 / K pieces. For this reason, the scaling process (100 / (100 / K)) is simply performed at the processing scaling factor (= display scaling factor) using the 100 / K number of data as a base (minimum unit for reading image data). Thus, it is possible to create plate-making data having the number of data that does not have any fraction due to the influence of the resolution conversion coefficient. That is, in this embodiment, the minimum unit of the number of image data to be captured is not 100 but 150 (100 / K), and if the scaling factor is 100%, 100 out of 150 is regarded as the effective number of data. It will be processed.
[0028]
Further, one of the first to third image expansion rate equations is selected from the detection results of the temperature sensor 10 and the humidity sensor 11 (step S5), and the number of prints set based on the selected image elongation rate equation is selected. The correction coefficient is calculated by a method described later (step S6). Then, the corrected plate making data is created by multiplying the plate making data by this correction coefficient (step S7), and the corrected plate making data creating means is executed here.
[0029]
When the corrected plate-making data is created, a master is made based on the corrected plate-making data (step S8), the master is wound around the outer periphery of the plate cylinder 3 (step S9), and the master is wound. Printing on the paper is performed by rotating the plate cylinder 3, contacting and separating the press roller 4 with respect to the plate cylinder 3, paper feeding between the plate cylinder 3 and the press roller 4, and the like (step S10). .
[0030]
Here, a method for obtaining the correction coefficient from the image expansion rate equation will be described. The solid line in FIG. 5 is a graph for obtaining the first image expansion rate equation shown in FIG. 3, and the image expansion rate equation relating to this graph is registered in the ROM of the control unit 8. If the set number of prints is 1000, the expansion amount of the image printed on the paper when the number of prints is approximately half the set number of prints (about the 500th print number) is “0”. Is obtained (corresponding to the equation indicating the broken line graph in FIG. 5), and the elongation rate indicated by the intersection when the broken line graph and the number of printed sheets is “0” (here, − 0.075%), the correction coefficient “0.99999” when printing 1,000 sheets can be obtained.
[0031]
In other words, corrected magnification-making data (for example, the magnification is 200% × 0.99999 = 199) is obtained by multiplying the magnification ratio (for example, 200%) of the data for plate-making by multiplying this correction coefficient. .85% of the data for plate making) can be obtained, and the master is made from this corrected plate making data and printing is performed on 1000 sheets of paper. Thus, the dimensional reproducibility of an image of 1000 printed sheets is improved.
[0032]
Also, in FIG. 5, when the set number of prints is 2000, the amount of expansion of the image printed on the paper when the number of prints is approximately half of the set number of prints (about 1000th print number) Is an image elongation rate formula (corresponding to a formula showing a one-dot chain line graph in FIG. 5), and an elongation rate (shown by the intersection point when the number of printed sheets is “0”) Here, from −0.15%), the correction coefficient “0.9985” when printing 2000 sheets can be obtained. Then, the corrected plate-making data can be obtained by multiplying the magnification ratio of the plate-making data by this correction coefficient to correct the magnification, and the master is made from the corrected plate-making data to obtain 2000 sheets. By performing printing on the paper, the expansion of the image becomes “0” on the approximately 1000th paper, and the dimensional reproducibility of the printed 2000 paper is improved.
[0033]
Here, when the temperature condition and the humidity condition are different, the second image elongation rate equation or the third image elongation rate equation described in FIG. 3 is selected, and the correction coefficient is obtained from the image elongation rate equation. Then, corrected plate-making data is created by multiplying the scaling factor of the plate-making data by a correction coefficient.
[0034]
In the present embodiment, as shown in FIG. 3, three image elongation rate expressions are prepared by combining temperature conditions and humidity conditions, and are detected from these image elongation rate expressions. The case where one image elongation rate equation is selected according to temperature and humidity and the correction coefficient is obtained from the image elongation rate equation has been described as an example. However, as the image elongation rate equation, only the temperature condition or Prepare the one corresponding to a combination of two or more of the temperature condition, the humidity condition, and the printing speed condition, and the image elongation rate formula. One of them may be selected to obtain the correction coefficient.
[0035]
In this embodiment, the stencil printing apparatus has the image reading unit 1 and the pixel density of the image reading unit 1 is different from the pixel density of the plate making unit 2 as an example. In the flowchart of FIG. 4 for explaining the plate making process, a case is shown in which processing (steps S3 and S4) for matching the pixel density of the image reading unit 1 to the pixel density of the plate making unit 2 is performed on the input image data. However, when the image density of the image reading unit 1 and the pixel density of the plate making unit 2 are the same, or stencil printing in which image data is input from an external device such as a personal computer without the image reading unit 1 In the apparatus, the processing in steps S3 and S4 described above is not necessary. That is, the corrected image-making data can be obtained by performing the processing of step S5 and subsequent steps on the input image data (plate-making data). The dimensional reproducibility of the image printed on the number of sheets of paper can be in the best state.
[0036]
【The invention's effect】
[0039]
According to the stencil printing apparatus of the first aspect of the present invention, the image elongation indicating the relationship between the number of prints printed from one master and the amount of elongation of the image printed on the paper due to the elongation of the master accompanying printing. The amount of expansion of the image printed on the paper when the number of prints is approximately half of the set number of copies when the storage unit that stores the rate formula, master plate making, and printing using the master are continuously performed Since it has a corrected plate-making data creation means for creating a corrected plate-making data by changing the magnification of the plate-making data for making the master based on the image expansion rate formula so that the value becomes “0”. Even if the master is stretched during printing, the master is based on the corrected plate-making data that has been corrected so that the stretch amount of the image printed on the paper becomes “0” when the number of prints is approximately half of the set number of prints. Is made, so the set mark In the printing of sheets, dimensional reproducibility of the printed image can be most improved state.
[0040]
According to the invention of claims 2 to 5, wherein temperature conditions, even when the humidity conditions, elongation amount of the master at the time of printing in accordance with various conditions such as printing speed condition varies, are prepared according to their various conditions Since one image elongation rate formula that meets the conditions at that time is selected from a plurality of image elongation rate formulas, and correction based on the selected image elongation rate formula is performed to obtain corrected plate-making data, Even when the amount of elongation of the master during printing varies depending on various conditions such as temperature conditions, humidity conditions, and printing speed conditions, the dimensional reproducibility of the printed image can be most improved.
[Brief description of the drawings]
FIG. 1 is a longitudinal front view showing an overall structure of a stencil printing apparatus according to an embodiment of the present invention.
FIG. 2 is a block diagram showing a control structure of the stencil printing apparatus.
FIG. 3 is a graph showing the results of examining the number of printed sheets and the amount of expansion of an image printed on paper in order to obtain an image expansion rate equation.
FIG. 4 is a flowchart for explaining master plate-making processing;
FIG. 5 is an explanatory diagram for explaining a method for obtaining a correction coefficient from an image expansion rate equation;
[Explanation of symbols]
1 image reading unit 2 plate making unit 3 plate cylinder
Step S7 corrected prepress data creation means

Claims (5)

Ink supplied to the inside of the plate cylinder while making a master corresponding to the image data in the plate making section, winding the master made around the outer periphery of the porous cylindrical plate cylinder, pressing the paper against the outer peripheral surface of the master In the stencil printing apparatus which oozes out from the perforated part of the master and prints an image on paper,
A storage unit for storing an image expansion rate expression indicating a relationship between the number of printed sheets from one master and the amount of expansion of an image printed on a sheet due to elongation of the master accompanying printing; master plate making; and When performing printing using the master continuously, the image expansion rate formula is set so that the expansion amount of the image printed on the paper becomes “0” when the number of prints is approximately half of the set number of prints. A stencil printing apparatus, comprising: corrected plate-making data creating means for creating corrected plate-making data by correcting the magnification of plate-making data for making a master based on the magnification. The image elongation expression, temperature conditions, humidity conditions, various conditions consisting of printing speed conditions, or, a plurality of prepared depending on the combination of these various conditions, one which conforms to the conditions at that time at the time of each print one One of the stencil printing machine according to claim 1, wherein the selected image elongation type, characterized in that so as to create the corrected plate making data. A plurality of image elongation rate formulas are prepared according to temperature conditions, and at the time of printing, any one of the image elongation rate formulas that meet the conditions at that time is selected to create corrected plate-making data. The stencil printing apparatus according to claim 1. A plurality of image elongation rate formulas are prepared according to humidity conditions, and at the time of each printing, any one of the image elongation rate formulas that matches the conditions at that time is selected to create corrected plate-making data. The stencil printing apparatus according to claim 1. A plurality of image elongation rate formulas are prepared according to printing speed conditions, and at each printing time, any one of the image elongation rate formulas that matches the conditions at that time is selected to create corrected plate-making data. The stencil printing apparatus according to claim 1, wherein

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