JP3791583B2 - Plate making method and stencil printing apparatus in stencil printing - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plate making method and a stencil printing apparatus in stencil printing, and more specifically, a plate making method for making a plate by punching an unperforated stencil sheet, and winding the stencil sheet thus made around a plate cylinder. The present invention relates to a stencil printing apparatus that performs printing on printing paper.
[0002]
[Prior art]
In a conventional stencil printing apparatus, generally, an image of a document is read by an image sensor or the like, and perforated stencil paper is punched by a plate making means such as a thermal head based on information of the read image. Printing is performed by performing so-called plate making, winding the pre-made stencil sheet around a plate cylinder, rotating the plate cylinder in a predetermined direction, applying printing pressure to the printing paper, and transferring ink.
[0003]
However, when the stencil stencil that has been subjected to plate making is wound around the plate cylinder and rotated, the printing paper and the plate cylinder are caused by the adhesive force of the ink transferred to the printing paper so as to ooze out from the stencil paper. The printing power is not separated from the plate cylinder, and the printed printing paper is wound around the plate cylinder, and then the printed printing paper is supplied to the printing cylinder after the wound printing paper. In some cases, the paper causes a so-called paper discharge jam or the stencil paper is damaged due to such a paper discharge jam.
[0004]
Therefore, by using a device called a separation claw, or in addition to that, by ejecting air from the tip of the separation claw, the printing paper fed out while the ink is transferred from the plate cylinder is removed from the plate cylinder. I was trying to separate them.
[0005]
[Problems to be solved by the invention]
However, if there is a portion with a high print density such as a so-called solid portion at the leading end of the stencil sheet in the rotational direction, the printing paper in that portion is caused by the adhesive strength of a large amount of ink in that portion. Since the adsorbing force between the plate cylinder and the part sticks to the plate cylinder, the leading edge of the stuck printing paper can be used even if the separation claw or the air jet is used. The printed printing paper is wrapped around the plate cylinder, and the printed printing paper and the subsequent printing paper fed to the printing cylinder cause a so-called paper discharge jam. There is a problem that the stencil sheet is sometimes damaged due to such a problem that it is caused, or due to such a paper discharge jam or the like.
[0006]
Further, when the leading end of the stencil sheet in the rotational direction is stuck to the plate cylinder, the leading end of the printing sheet is separated from the surface of the plate cylinder by the separation claw (that is, the stencil wound around it). In order to peel it off from the surface of the base paper, the tip of the separation claw must be inserted between the printing paper strongly attached from the tip and the stencil base paper. When approaching the surface of the paper, the probability that the tip of the separation claw touches the surface of the stencil paper or the printing side of the printing paper becomes extremely high, and printing defects such as separation claw marks appear on the printing paper ( In the printed image), or the surface of the stencil sheet is scratched, resulting in a problem that the printing quality after that may be deteriorated.
[0007]
In addition to problems such as mechanical printing defects and damage to the stencil sheet caused by such separation nails, strong air is applied to the leading edge of the printing paper that is stuck to the stencil sheet on the surface of the plate cylinder. In the method in which the front end of the printing paper is separated from the surface of the plate cylinder by spraying, the printing paper is strongly adhered to the plate cylinder at the solid portion, and the printing paper may not be separated even if strong air is blown. In that case, however, the back of the printing paper is pressed against the surface of the plate cylinder with rather strong air, which may have an adverse effect. Also, even if the printing paper is somehow separated, the printing surface of the solid part that has just been printed is particularly difficult to dry, so it is often in a semi-dry state, and the semi-dry ink is blown off by strong air There has been a problem that it may cause a printing failure or image deterioration by causing dripping or flow or bleeding.
[0008]
If the problem caused by such a phenomenon that the printing paper sticks to the plate cylinder cannot be solved, the paper discharge jam or the stencil paper may be damaged or the separation claw mark may be generated as described above. This eliminates the phenomenon of printing paper sticking to the plate cylinder because the advantage of high-quality printing, which is a very useful characteristic of the stencil printing machine, may be impaired. It has come to be desired.
[0009]
The present invention has been made to solve such a problem, and as a simple printing apparatus that eliminates the phenomenon of printing paper sticking to a plate cylinder and performs high-quality printing with high efficiency. An object of the present invention is to realize a plate making method and a stencil printing apparatus in stencil printing that make it possible to make use of the useful characteristics of the stencil printing apparatus.
[0010]
[Means for Solving the Problems]
The plate making method in stencil printing according to the present invention is a plate making method in stencil printing in which stencil sheet making is performed by punching an unperforated stencil sheet based on an image of the document. When the image density of a predetermined region in at least one peripheral part is equal to or higher than a predetermined density, a blank portion is provided over a predetermined distance from the leading edge of the stencil sheet, and the plate making is performed. .
[0011]
The plate making method in stencil printing according to the present invention is a plate making method in stencil printing, in which the stencil sheet is made by punching an unperforated stencil sheet based on an image of an original. When the image density of a predetermined area at the leading edge of the original corresponding to a portion is equal to or higher than a predetermined density, a blank portion is provided over a predetermined distance from the leading edge of the stencil sheet, and the plate making is performed. To do.
[0012]
Here, when the image density of the predetermined area at the leading edge of the original corresponding to the leading edge of the stencil sheet is equal to or higher than a predetermined density, punching is performed based on the original image having the image density lower than the predetermined density. The margin may be provided by punching an image corresponding to the image of the document at a magnification lower than the image magnification.
[0013]
The stencil printing apparatus of the present invention comprises a plate making means for making a stencil sheet by perforating an unperforated stencil sheet based on an image of an original, and a printing paper by winding the stencil sheet around a plate cylinder. A stencil printing apparatus having printing means for performing printing on the stencil printing apparatus, comprising: detecting means for detecting that an image density of a predetermined area in at least one peripheral part of the four peripheral parts of the document is equal to or higher than a predetermined density; When it is detected that the means exceeds the predetermined density, a blank portion is provided over a predetermined distance from the front end of the stencil sheet, and the plate making is performed.
[0014]
Further, the stencil printing apparatus of the present invention comprises a plate making means for making a stencil sheet by punching an unperforated stencil sheet based on an image of an original, and winding the stencil sheet on a plate cylinder. A stencil printing apparatus having printing means for printing on a printing paper, comprising: a detecting means for detecting that the image density of a predetermined area at the leading edge of the document corresponding to the leading edge of the stencil sheet is equal to or higher than a predetermined density; When the plate making means detects that the density is equal to or higher than the predetermined density, the plate making is performed by providing a blank portion over a predetermined distance from the leading end of the stencil sheet. Yes.
[0015]
Further, the plate making means performs punching of an image corresponding to the image of the document at a magnification lower than the magnification of the image when performing punching based on the image of the document with the image density less than a predetermined density, You may make it provide a margin part.
[0016]
Further, a plate making means for making a stencil sheet by punching an unperforated stencil sheet based on an image of a document, and a printing means for printing on a printing sheet by winding the stencil sheet around a plate cylinder. In the stencil printing apparatus, the image density of a predetermined region at one end of the both ends of the original corresponding to the front end and the rear end of the stencil sheet is equal to or higher than a predetermined density, and the other end Detecting means for detecting that the image density of the predetermined area is less than the predetermined density, and when the plate making means detects that the image density of the predetermined area at the other end is less than the predetermined density Is characterized in that the plate making is carried out so that the end portion of the lower density is corresponding to the front end portion of the stencil sheet.
[0017]
Moreover, when providing the said margin part, you may make it further provide the alerting | reporting means which alert | reports that to at least any one among visual information and audio | voice information.
[0018]
Also, in such a case, when making a plate at a lower image magnification, that is, when the image is made substantially smaller than the normal case, that fact and the image density is lower than a predetermined density. At least one of performing punching of an image corresponding to the image of the original at a magnification lower than the image magnification when punching based on the image and reducing the image printed on the printing paper, It is good also as what further provided the alerting | reporting means to alert | report by visual information, audio | voice information, etc.
[0019]
In other words, in the present invention, if there is a solid portion having a high density even on one side among four peripheral portions (four sides) of a document whose outer shape is generally rectangular, there is a phenomenon that the printing paper sticks to the plate cylinder during printing. A margin is provided at the front end of the stencil sheet in the rotational direction. Here, at the document reading stage, it may be undecided which one of the four peripheral portions of the document will eventually become the leading end portion in the rotation direction of the plate cylinder, so that the solid area is the four peripheral portions of the document image. In any case, since a phenomenon in which the printing paper sticks to the plate cylinder may occur, a blank portion is provided at the front end portion of the stencil sheet.
[0020]
Alternatively, since one of the four peripheral portions of the document corresponds to the leading edge of the stencil paper, it is often determined (known) in advance. If the image density on one side of the original corresponding to is checked and it is determined that the image density is a high density corresponding to a solid that causes sticking of the printing paper to the plate cylinder, the stencil sheet A blank portion is provided at the front end in the rotational direction when the plate is placed on the plate cylinder.
[0021]
The size of the margin may be set so that the printing paper is reliably separated from the plate cylinder by a separation claw or air blowing. Alternatively, an interval may be set such that the printed printing paper can be separated from the blank portion by its own weight, elasticity of the printing paper itself, drying of ink, and the like. More detailed settings for the margins vary depending on various conditions such as separation claw settings, air flow rate, printing paper elasticity, ink viscosity and drying time, and so on. do it.
[0022]
Further, in providing the margin, it is effective to shift the punching start position from the front end toward the rear end, but in addition to that, the size of the image to be made on the stencil sheet, that is, the perforation area is determined. A method of reducing the size of the stencil sheet from a normal perforated region is also a preferable aspect.
[0023]
In addition, shifting the position of the image to be made on the stencil sheet to reduce the position of the image to be made on the stencil sheet in order to provide the margin part as described above means that the image to be printed on the printing paper by the stencil sheet is shifted in that way. Therefore, it is desirable to notify the user beforehand.
[0024]
Further, by providing means for allowing the user to select whether or not to provide the above-described margin portion, the user can make a stencil sheet or a printing sheet based on information notified before the start of printing. It is also possible to select the result of the determination after determining whether or not the above-described margin portion may be provided.
[0025]
That is, when the margin is provided by shifting the leading edge of the image to be printed on the printing paper from the leading edge of the printing paper, for example, when there is almost no image (pattern) at the trailing edge of the original image, the user There is no practical inconvenience even if it is selected to provide a margin at the tip, so the user can select it. Alternatively, when a margin is provided by reducing the image to be printed on the printing paper, for example, when the user performs printing using a precise 1/1 design drawing as a document or printing using a 1 / 50,000 map as a document. Then, it is desirable that the image finally obtained by printing has a size (magnification) corresponding to 1: 1 with respect to the image of the document. Therefore, in such a case, the user may be able to select 1/1 printing without intentionally selecting reduced printing for providing a blank portion. In addition, when the user performs printing based on a general home-use photo manuscript or illustration manuscript, there is no practical problem even if the print image is somewhat reduced, and printing on the plate cylinder is thus provided by providing a margin. This is preferable because the winding of the paper can be eliminated. Rather, in this case, a margin can be provided around the entire printed image, and as a result, the image layout on the printing paper can be made to appear more natural, which is preferable.
[0026]
【The invention's effect】
According to the present invention, in the plate making method and stencil printing apparatus in stencil printing, there is a solid portion at a high density so that the phenomenon that the leading end of the stencil sheet sticks to the plate cylinder tends to occur. If this is the case, it is detected by a detection means, and a margin is provided at the leading edge of such a stencil sheet, thereby eliminating the phenomenon of the printing paper sticking to the plate cylinder and improving the printing quality. It is possible to make use of the extremely useful characteristic of a stencil printing apparatus as a simple printing apparatus that performs printing with high efficiency.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0028]
(Embodiment 1)
FIG. 1 is a diagram showing a schematic configuration of mainly a mechanism portion of a stencil printing apparatus according to the present invention. FIG. 2 is a block diagram schematically showing a schematic configuration of a control system in the stencil printing apparatus.
[0029]
This stencil printing apparatus is a stencil printing apparatus with a stencil making function for making a stencil by perforating an unperforated stencil sheet R based on an image read from a document 2 (hereinafter also referred to as a document image). The document reading unit 1, the plate making unit 3, the stencil printing mechanism unit 5, the plate discharging unit 7, the paper feeding unit 9, the paper discharge unit 11, the image processing unit 101, the density detection unit 102, and the like And a control unit 100 for controlling the mechanical operation and data processing operation of each part.
[0030]
Here, as a correspondence relationship with each unit in each claim, the plate making unit 3 and the control unit 100 that controls the plate making unit 3 are the plate making unit, and the stencil printing mechanism unit 5 and the control unit 100 that controls the printing unit are the printing unit. Needless to say, the density detection unit 102 and the control unit 100 that controls the density detection unit 102 correspond to detection means.
[0031]
More specifically, the document reading unit 1 reads the image of the document 2 by using a document set table 21 using a tempered glass plate on which the document 2 is placed, and converts it into an electrical signal carrying the image information. And an image sensor moving motor mechanism 32 that mechanically scans the image sensor 31 with respect to the document 2, and a reference position sensor 33 that detects the moving position of the image sensor 31.
[0032]
There are mainly two types of document image reading methods (reading methods and apparatus configurations) in the document reading unit 1. That is, first, one original image is read and stored as a set of image data in a storage means such as a cache memory (RAM) 105 using a RAM (Random Access Memory) 105, and the like. There is a method in which the image data is batch-read from the storage means when the stencil sheet R is made and used to drive the thermal head 35. Second, the information of the original image read by the image sensor 31 is sent to the thermal head 35 after being subjected to A / D conversion and data processing in a time-series manner without being stored in the storage means. There is a method. In the case of the method described in the first, a storage means such as the RAM 105 for temporarily storing the read image data is required. However, after reading the entire image of one document 2, the data on the stencil sheet R is read. Since perforation can be performed, there is an advantage that the density of both the front end portion and the rear end portion of the image can be detected based on the read image data, but during the time when the document 2 is being read. There is a time lag that the drilling operation cannot be performed. In the case of the second method, the image data obtained by reading from the document 2 can be immediately sent to the thermal head 35 to execute the punching operation. Although there is an advantage that almost no time lag occurs between the operations, the density detection at the front end of the document 2 can be detected by reading the position first, but the punching is almost completed. Until then, it is practically impossible to detect the density of the trailing edge of the document image. Accordingly, in consideration of such points, it is only necessary to appropriately determine which of the above-described methods is desirably employed as the document reading unit 1.
[0033]
The plate making unit 3 includes a thermal head 35, a platen roller 37, a pair of base paper conveying rollers, a platen roller 37, and a base paper, each of which includes a main part configured to perforate the stencil base paper R corresponding to the original image. A stepping motor 41 that rotationally drives the conveying roller pair 39a and 39b and a base paper cutter 43 are provided. When the stencil sheet R stored in the roll shape is pulled out, the plate making unit 3 carries image information read from the document 2 by the document reading unit 1 while scanning the stencil sheet R in the so-called sub-scanning direction. The thermal head 35 perforates the stencil sheet R on the basis of the image data obtained from the electrical signal, thereby performing the plate making. At this time, the platen roller 37 plays a role of pressing the stencil sheet R against the thermal head 35. The stencil sheet R thus made is fed out by a pair of stencil conveying rollers 39a and 39b, and the rear end thereof is cut by a stencil sheet cutter 43 so as to have a size suitable for the sheet size of the printing sheet P.
[0034]
The stencil printing mechanism 5 includes a cylindrical plate cylinder 45 that can bleed ink and rotates about the rotation axis, and a base paper that is provided on the outer peripheral surface of the plate cylinder 45 and mechanically grips the leading end of the stencil sheet R. An ink supply mechanism 53 having a clamp 47, a squeegee roller 49 and a doctor roller 51 disposed in the plate cylinder 45, a main motor 55 for rotating the plate cylinder 45 in a predetermined direction, and a printing paper together with the plate cylinder 45 A press roller 59 that applies printing pressure with P interposed therebetween, and a press control mechanism 61 that controls the vertical movement of the press roller 59 are provided. A magnet piece 85 is attached to the end of the plate cylinder 45. When the plate cylinder 45 reaches the plate start rotation position, a plate start position sensor 87 for detecting this by the magnetism of the magnet piece 85 is provided. It is provided close to the plate cylinder 45. A rotary encoder 89 is attached to the main motor 55, and the rotational position of the plate cylinder 45 is quantitatively determined based on the plate start position of the plate cylinder 45 based on the output of the plate start position sensor 87. Can be detected.
[0035]
The plate discharging unit 7 peels the stencil sheet S that has been made and used from the plate cylinder 45 and discharges the plate, and a plate discharging box 63 that accommodates the stencil sheet S that has been peeled and discharged. And a transmissive stencil discharge sensor 69 that detects the passage of the stencil sheet S at the position of the stencil conveying roller pair 65.
[0036]
The paper feed unit 9 takes the print paper P placed thereon and moves up and down by a vertical movement mechanism (not shown) and the print paper P placed on the paper feed base 71 one by one. The pickup roller 73, the sheet feeding clutch 75 that interrupts the driving force transmitted from the main motor 55 to the pickup roller 73, and the printing cylinder P and the press roller in synchronism with the rotation of the plate cylinder 45. 59 is provided with a sheet conveying roller pair 77 that is fed between the sheet conveying roller 59 and a transmissive sheet sensor 79 that detects the presence or absence of the printing sheet P at the position of the sheet conveying roller pair 77.
[0037]
The paper discharge unit 11 includes a separation claw 81 that separates the printed printing paper P from the plate cylinder 45, and a paper discharge tray 83 on which the printed printing paper P is placed so as to be stacked. The separation claw 81 has a nozzle-like tip, and promotes the effect of separating the printing paper P from the plate cylinder 45 by blowing air from the tip.
[0038]
The control unit 100 operates each of the document reading unit 1, plate making unit 3, stencil printing mechanism unit 5, plate discharging unit 7, paper feeding unit 9, paper discharge unit 11, image processing unit 101, and density detection unit 102. Are controlled while being synchronized as necessary. The control unit 100 executes various control functions using a so-called microcomputer (microcomputer) that executes a control function based on a system program stored in advance in the ROM 103 or the like, and various operations related to the operation of the stencil printing apparatus. Display unit 106 for displaying information, a plate making start key, a printing start key, a printing mode setting key, a numeric keypad used for inputting the number of copies, a reset key, a job emergency stop key, etc. (all not shown) And an operation unit 107 having an operation panel (not shown) for inputting a command for selecting an operation mode of the stencil printing apparatus, a command for selecting whether or not to shift the plate making start position, and the like.
[0039]
When the density detection unit 102 detects that the density of the leading edge of the document 2 is equal to or higher than the predetermined density, the control unit 100 removes a blank portion from the leading edge in the rotational direction of the plate cylinder 45 over a predetermined distance. In order to perform the plate making so as to be provided at the front end portion of the stencil sheet R, the drive of the thermal head 35 is controlled so as to start punching from a position shifted from the normal punching start position toward the rear in the rotational direction of the plate cylinder 45. To do. In other words, punching is performed in a region shifted by the amount of the blank portion from the normal punching region when the density of the front end portion of the document 2 is less than the predetermined density. More specifically, there are mainly two methods as a method for executing such a shift of the punching start position (shifting of the punching region). That is, first, when the density of the leading edge of the document 2 is equal to or higher than a predetermined density, the leading edge of the stencil sheet R is moved by the thermal head 35 at the time when the punching by the thermal head 35 is started. There is a so-called mechanical method in which a predetermined distance is drawn ahead of the 35 heat generating element arrays, and the margin can be obtained by extending the predetermined distance. Secondly, the mechanical feed position of the front end portion of the stencil sheet R at the start timing of perforation by the thermal head 35 is the same as in the normal case (that is, when the concentration of the front end portion of the document 2 is less than a predetermined concentration). On the other hand, there is a so-called image data method in which dummy margin data that can provide the margin is added to image data input to the thermal head 35. It goes without saying that either of these can be used, but in any case, the perforation corresponding to the image at the rear end will deviate (extrude) backward from the original perforation region. Ink exuded from the stencil sheet remains untransferred to the printing paper P, and the plate cylinder 45 and its surroundings are stained with ink, and the subsequent printing paper P is stained with ink that has not been transferred, When the stencil sheet R is cut to a normal size, the rear end part of the stencil sheet R cut out from the normal perforation area is cut in the middle, and the next part of the stencil sheet R to be stenciled next time There may be inconveniences such as the presence of extra perforations before. Therefore, when there is a high possibility that such inconvenience will occur, when shifting the punching start position of the leading end portion of the stencil sheet R, the portion protruding from the trailing end portion is not punched at the same time. It is desirable to take such measures. For example, in the case of the first method, the thermal head 35 is perforated more than usual in order to prevent the rear end from being perforated over a distance similar to the predetermined distance of the front end. It may be forced to stop a little earlier. Alternatively, in the case of the second method, if a method is used in which image data having the same amount of data as the margin data added to provide a margin portion at the front end portion is deleted from the image data at the rear end portion. Good.
[0040]
However, the perforation area is shifted in order to provide such a margin part, or there is a possibility that a margin part may be formed at the leading edge of the image printed on the printing paper P by shifting such a perforation area. Is displayed on the display unit, and only when the user has selected to execute shifting of the punching area in such plate making (the user has input a command to that effect), such a Perform plate making with different drilling areas. Alternatively, when the user does not select a plate making for shifting the perforated area (the user inputs a command to that effect to the operation unit), the user does not shift the perforated area and provide a blank portion. A general plate making to a normal drilling area is started, starting from the drilling start position. Furthermore, if both the leading edge and the trailing edge of the document are both higher than a predetermined density, the display unit indicates that the image at the trailing edge of the high density will be cut slightly. You may make it display.
[0041]
The image processing unit 101 digitizes an electrical signal carrying image information read from the document 2 by the document reading unit 1 by performing A / D conversion, and performs general image processing. Image data for performing a punching operation by the thermal head 35 is obtained.
[0042]
The density detector 102 detects whether or not the density of the predetermined area at the front end portion of the original image read by the original reading section 1 is equal to or higher than the predetermined density. Whether it is above or not is detected. That is, generally, the outer shape of the document 2 is often a rectangle such as a rectangle, and at the stage when the document 2 is set on the document setting table 21, one of the four peripheral edges of the document 2 is a stencil. In many cases, it is determined whether or not it corresponds to the leading end portion of the base paper R (the leading end portion in the rotation direction that is attached to the plate cylinder 45 and rotates). Therefore, first, it is detected whether or not the leading edge of the original image corresponding to the leading edge of the stencil sheet R has a density higher than a predetermined density. Is caused at the leading edge of the printing paper P, there is a high probability that the printing paper P will stick to the plate cylinder 45, so in order to prevent such a bad phenomenon from occurring, It is detected that the leading edge of the document image has a predetermined density or higher. Furthermore, in the present embodiment, it is detected whether or not the rear end portion of the document image has a density higher than a predetermined density.
[0043]
There are mainly two methods for detecting the density of the leading edge and the trailing edge of the original image. First, a predetermined area corresponding to the leading edge of a document image based on image data read from the document 2 by the image sensor 31 and subjected to A / D conversion (analog / digital conversion) processing, data processing, or the like. There is a method of detecting the density of the image. Second, in addition to the image sensor 31, a density detection sensor or the like (not shown) dedicated to density detection in a predetermined area at the front end of the document image is provided, and the document 2 is set on the document setting table 21. There is a method of performing density detection at a stage without depending on (independently) reading of an original image by the image sensor 31. That is, in the first method, the existing image sensor 31 and the image processing unit 101 can be used as a part of the density detection unit 102, so that it is unnecessary to add density detection hardware or the like. Although there is an advantage that the detection unit 102 can be easily realized by, for example, software implementation, it is substantially possible to detect the density of the leading edge of the document image until the image data is obtained by reading the image from the document 2. Is impossible. If this is practically acceptable, the first method may be employed. Further, in the second method, in addition to the existing image sensor 31 and the image processing unit 101, hardware such as a reflective optical sensor for detecting image density and a density measuring circuit (both not shown) must be added. However, in practice, such an additional amount is not so complicated in many cases, and immediately after the process of reading the original image and obtaining the image data, the original image is immediately set when the original 2 is set. There is an advantage that it is possible to detect the concentration of the tip portion of the.
[0044]
Further, there are two more methods for the detection method described in the first section. That is, first, a so-called pre-scan method is adopted, in which a document image is separately scanned for reference such as the density of the document image before obtaining the document image data used for plate making. In this case, there is a method of detecting the density of the leading edge and the trailing edge of the image when the image data is obtained by the prescan. Secondly, when a method is adopted in which when an original image is read, the image data is sequentially sent to the thermal head 35 to perform punching, reading is started from the leading end of the image. The density of the image read over a predetermined area at the tip is detected. It goes without saying that each of these methods may be properly used in consideration of the respective characteristics.
[0045]
The predetermined density and the predetermined area include the weight and elasticity of the printing paper P, the viscosity and drying time of the ink, the setting of the separation claw 81, the flow velocity of air blown from the tip of the separation claw 81, and the like. Since the preferred setting varies depending on various conditions, it may be set appropriately corresponding to each factor. For example, as an example of a regular plain paper such as a general A4 size, an area extending from a distance of 10 mm to 25 mm from the most advanced portion is set as the predetermined area, and a complete solid state with the highest density is set to 100. As a percentage, a solid state with a high density of 75% may be set as the predetermined density. The setting of the predetermined area and the predetermined density is merely an example. As described above, the specifications of the printing paper P and ink, the separation distance between the separation claw 81 and the plate cylinder 45, and the air blow Needless to say, it is desirable to set appropriately based on various factors such as strength.
[0046]
Next, an outline of a series of operations from the document reading process through the plate making process to the printing process in the stencil printing apparatus according to the first embodiment having the main part as described above will be described. FIG. 3 is a flowchart showing an outline of a series of operations from reading an original to executing printing through plate making in the stencil printing apparatus according to the first embodiment.
[0047]
The document 2 is set on the document setting table 21, and the operation unit is operated by the user, and the document image reading operation in the document reading unit 1 is started (S1). The electric signal carrying the information of the read original image is further transmitted to the image processing unit 101, subjected to A / D conversion and data processing, and stored as image data in the RAM 105 for image memory. (S2). By extracting and examining the data corresponding to the predetermined area at the front end of the original image from the image data obtained at this time (S3), the predetermined area at the front end of the original image (original 2 in this embodiment) is examined. Whether or not the area defined by the distance and the entire width extending from 10 to 15 mm from the leading edge to the trailing edge of the image is a solid image having a high density higher than a predetermined density (75% or more of the maximum density in the present embodiment). The density detector 102 detects this (S4). At this time, if the density is less than the predetermined density (N in S4), the probability of the printing paper P sticking to the plate cylinder 45 is low, so punching is started from the normal position with respect to the stencil sheet R and the normal area is reached. A general plate making process is performed to perforate (S5). Then, the stencil printing mechanism unit 5 performs general printing using the stencil sheet R made by such a general method on the printing paper P such as regular plain paper such as A4 size. (S6).
[0048]
However, if the density is equal to or higher than the predetermined density (Y in S4), whether or not the predetermined area such as the area extending from 10 to 15 mm at the rear end of the original image is a solid image having a density higher than the predetermined density. This is detected by the density detector 102 (S7). At this time, if the rear end portion of the document image is less than the predetermined density (N in S7), an indication that the front end portion of the document 2 is slightly shifted from the normal case, or that such plate making is performed. For example, a display indicating that the print area on the print paper P is slightly shifted from the normal case by executing the shift is displayed on the screen of the display unit 106 using a display device such as a liquid crystal display panel. For example, it is displayed in Japanese notation formed by combining kanji and hiragana (S8). Whether or not it is actually possible to perform the plate making by shifting the start position (that is, the punch area) of such punching from the start position of the normal punching on the stencil sheet R over a predetermined distance backward. The user selects (S9). At this time, if it is selected that the plate-making may be shifted and executed (Y in S9), the plate-making portion 3 is executed by shifting the tip portion over a predetermined distance (S10). In this way, the stencil printing mechanism unit 5 performs printing using the stencil sheet R which has been made by shifting the perforated area more actively than a normal distance by a predetermined distance (S11).
[0049]
Alternatively, at this time, if the user has not selected to shift the plate making (N in S9), for example, the display unit 106 may indicate that “making this document as it is may make it easy to cause paper discharge jam”. (S15), the plate making unit 3 performs perforation starting from the normal position on the stencil sheet R to perform general plate making (S5). Then, the stencil printing mechanism unit 5 performs general printing on the printing paper P using the stencil sheet R made by such a general method (S6).
[0050]
On the other hand, if the trailing edge of the original image has a predetermined density or more in S7 (Y in S7), the fact that the leading edge of the original 2 is shifted from the normal case and printing on the printing paper P is performed. In addition to notifying that the area will be slightly shifted from the normal case, the display unit 106 displays that the image at the rear end is to be cut over a short distance (S12). Then, based on such display, the user determines whether or not a margin may be provided at the leading edge of the image to be printed at that time (S13), and the image at the trailing edge is slightly cut at the same time. (S14) and if it is determined that there is no problem (Y in S13 to Y in S14), an instruction to execute it is input via the operation unit. Then, plate making with the tip portion shifted over a predetermined distance is executed by the plate making unit 3 (S10). Then, the stencil printing mechanism unit 5 executes printing using the stencil sheet R that has been made (S11).
[0051]
However, here, when it is not preferable for the user to provide a slight margin at the leading edge of the image to be printed (N in S13), or when it is not preferable for the user that the image at the trailing edge is slightly cut. In (N of S14), when the user inputs an instruction not to select the plate making shift, first, according to the instruction, “if this original is made as it is, there is a possibility that a paper discharge jam is likely to occur”. Is displayed on the display unit 106 (S15), and the plate making unit 3 starts punching from a general position and executes general plate making such that a normal region for the stencil sheet R is punched (S5). . The stencil printing mechanism 5 performs general printing on the printing paper P using the stencil sheet R made by such a general method (S6).
[0052]
As described above, the density of the front end portion of the original image, that is, the density of the portion corresponding to the front end portion in the rotation direction when the stencil sheet R made on the basis of the original image is placed on the plate cylinder 45, In the case where the density of the printing paper P is high enough to cause the phenomenon that the printing paper P sticks to the plate cylinder 45, a margin over a predetermined distance such as a distance of 10 to 15 mm from the leading edge of the stencil sheet R toward the trailing edge. The stencil is made by shifting the punching start position for the stencil sheet R so as to provide a portion. Since the printing paper P does not stick to the blank portion provided at the front end portion of the stencil sheet R in this way during printing, the front end portion of the printing paper P after printing is easily separated from the plate cylinder 45. Become. Thereby, it is possible to prevent the printing paper P from sticking to the plate cylinder 45, and it is possible to make use of the useful characteristics of the stencil printing apparatus as a simple printing apparatus that performs printing with high printing quality with high efficiency. In addition, by providing a margin portion at the front end portion of the stencil sheet R, the image printed on the printing paper P is provided with a margin portion to which ink is not transferred to the front end portion of the plate cylinder 45 in the rotation direction. Since it is easy to separate from the curved surface of the plate cylinder 45 due to the elasticity of the paper, the separation claw 81 can easily enter the separated portion. Accordingly, the separation claw 81 does not need to be brought close enough to contact the plate cylinder 45, and printing defects such as conventional separation claw marks and damage to the stencil sheet R due to contact with the separation claw 81 are caused. Can be resolved. Moreover, since the ink is not transferred to the margin of such a tip, even if air is strongly blown from the tip of the separation claw 81 to that portion, there is no occurrence of an ink blowing phenomenon due to the air. Further, it is possible to reliably separate the printing paper P from the plate cylinder 45 while making it possible to prevent the deterioration of printing quality and the occurrence of printing defects due to such an ink blowing phenomenon.
[0053]
Moreover, when shifting the drilling position as described above, the fact is displayed on the display unit 106 to notify the user in advance, and the user actually shifts the drilling position based on the display. Whether or not can be selected before the start of actual plate making. Furthermore, if the trailing edge of the document image has a predetermined density or more, if the leading edge is shifted as described above, the trailing edge image may be cut at least by that amount. It is possible to notify the user in advance, for example, by displaying that fact on the display unit 106 so that the user can select whether or not it is possible before the actual plate making is started. In this way, the user can select whether or not to execute the plate making with the piercing area shifted in an interactive manner by informing the user beforehand when starting the plate making with the piercing area shifted. It becomes possible.
[0054]
In the first embodiment, the density of both the leading edge and the trailing edge of the document image is detected. However, the density detection of the trailing edge and the display of the detection result are omitted, and the document is omitted. Detect the density only at the leading edge of the image, and if the leading edge has a higher density than the predetermined density, display that fact, and if the user selects it, make the plate making so that a margin is provided. You may make it perform. That is, the process of detecting or displaying the image density at the trailing edge of the document 2 as shown in S7, S12, S13, and S14 in the above flowchart is omitted, and the process directly proceeds from S4 to S8. You may make it do.
[0055]
Alternatively, in the first embodiment, when it is detected that the leading edge of the document image has a high density equal to or higher than a predetermined density and the trailing edge has a low density lower than the predetermined density (S4). Y and S7, N), instead of S8 to S11 shown in the above flowchart, plate making may be started from the rear end portion of the original image having a low density. The stencil sheet R can also be made by performing plate making so that the rear end portion of the original image having a low density corresponds to the front end portion in the rotational direction when the plate cylinder 45 of the stencil sheet R is attached. It is possible to prevent the phenomenon that the printing paper P sticks to the front end in the rotation direction. However, when printing using the stencil sheet R made in this way, the original image top (or left and right) and the printed image top (or left and right) are reversed. For example, when the user uses the sorter to print (bookbinding) the printing paper P after printing, it is inconvenient because only that page is partially reversed from the other pages. That is, in such a case, as shown in an example in the flowchart of FIG. 4, for example, a message such as “Are you sure you want to start plate making from the rear end side?” Is displayed on the display unit. This is notified to the user (S16). If the user selects it as acceptable (Y in S17), the plate making unit 3 punches (plate making) the stencil sheet R from the rear end of the document image (S18), and the stencil sheet thus made is made. Printing using R is performed by the stencil printing mechanism unit 5 (S19). However, here, when the user does not select such plate making from the rear end, or when the sorter is used (it is detected that the sorter is active) (N of S17), The plate making unit 3 executes a general plate making such that a normal area of the stencil sheet R is perforated (S5), and the stencil printing mechanism unit 5 uses the stencil sheet R made by such a general method. The general printing performed is executed (S6). In this way, when the rear end portion of the original image has a low density, plate making is performed so that the image of the low end rear end portion comes to the front end portion in the rotation direction of the stencil sheet R. In addition, the phenomenon that the front end portion of the printing paper P sticks to the plate cylinder 45 can be eliminated.
[0056]
(Embodiment 2)
FIG. 5 is a flowchart showing an outline of the operation of the stencil printing apparatus according to the second embodiment. In the second embodiment, in order to provide the same blank portion as that in the first embodiment at the front end portion of the stencil sheet R, the entire punching area is generally not performed by shifting the punching start position. It is characterized by being reduced more than usual in the case of simple plate making. In other respects, the same technique as that of the first embodiment is employed.
[0057]
However, in this second embodiment, the image size printed when printing is performed using the stencil sheet R made by making the entire punched area smaller than in the case of general plate making is generally 1. Although the image is reduced as compared with an image printed with a setting of: 1, it may not be preferable for the user. This is because, for example, when the user performs printing using a precise 1/1 design drawing as a manuscript or printing using a map such as a 1 / 50,000 map as a manuscript, the image finally obtained by printing is obtained. In many cases, it is desirable to have a size (magnification) corresponding to 1: 1 for an image of a document. Therefore, in such a case, it is desirable that the user can select plate making and printing at 1/1 magnification (equal magnification) without intentionally selecting reduced plate making and reduced printing for providing a blank portion. become. On the other hand, when the user performs printing based on a general home-use photo manuscript or illustration manuscript, there is no practical problem even if the print image is somewhat reduced. 45 is preferable because it is possible to eliminate the wrapping of the printing paper P with respect to 45, but in this case, if a margin can be provided around the entire printed image, the image layout on the printing paper P is consequently changed. It can be said that it is possible to make it appear more natural. For this reason, it is desirable that the user can select a plate making with a reduced image based on the type of original, the purpose of use of the printed material, and the like. A technique including making it possible to select a plate-making process in which such an image is reduced is a main feature in the second embodiment. Therefore, in the description of the second embodiment, in order to simplify the description, detailed description of the same parts and operations as those of the first embodiment is omitted, and the difference from the first embodiment. Of the points, the following description will be made in detail with a focus on the process of making the image by reducing the image as compared with the normal case.
[0058]
In the stencil printing apparatus according to the second embodiment, when the density detecting unit 102 detects that the density of the leading edge of the original image is higher than a predetermined density, the control unit 100 controls the plate making unit 3. By automatically controlling the plate-making operation and punching an image smaller than the size of the image punched by normal plate-making, the same margin as in the first embodiment is provided at the leading end of the stencil sheet R. .
[0059]
That is, first, the document 2 is set on the document setting table 21, and the operation unit is operated by the user to start the document image reading operation in the document reading unit 1 (S21). The electrical signal carrying the information of the read original image is further transmitted to the image processing unit 101, subjected to A / D conversion and data processing, and stored as image data in storage means such as the image memory RAM 105. It is temporarily stored (stored) (S22). By extracting and examining the data corresponding to the predetermined area at the front end of the original image from the image data obtained at this time (S23), the predetermined area at the front end of the original image (original 2 in this embodiment) is examined. Whether or not the area defined by the entire width of the image and the distance extending from 10 to 15 mm from the leading edge to the trailing edge is a solid image having a high density higher than a predetermined density (75% or more of the maximum density in this embodiment). Is detected (S24). At this time, if the density is less than the predetermined density (N in S24), the probability of the printing paper P sticking to the plate cylinder 45 is low, so punching is started from the normal position with respect to the stencil sheet R and the normal area is reached. A general plate-making process for punching is performed (S25). The stencil printing mechanism unit 5 performs general printing using the stencil sheet R made by such a general method on the printing paper P such as regular plain paper such as A4 size (for example). S26).
[0060]
However, here, when the density is equal to or higher than the predetermined density (Y in S24), in order to provide a margin part over a predetermined distance at the leading end of the stencil sheet R, the plate making is slightly reduced compared with the case of normal plate making. The display unit 106 displays a display indicating that the print area (image) on the printing paper P is slightly reduced as compared with the normal case by executing such plate-making reduction. It is displayed on the screen (S28). Then, the user selects whether or not to actually reduce the image size of the punching (that is, to reduce the punching area) (S29). At this time, for example, the original image may be somewhat reduced as in a general photograph or illustration, but by reducing the size, a margin portion is provided at the peripheral edge of the printing paper P, which is preferable in terms of image layout. In the case of such a manuscript, it is selected that the image to be subjected to plate making may be reduced (Y in S29), and such reduced plate making is executed by the plate making unit 3 (S30). Then, the stencil printing mechanism unit 5 executes printing using the stencil sheet R thus made (S31).
[0061]
Or at this time, if the original image is an image that is required to be printed at exactly 1: 1 as in a precise design drawing, for example, it is not preferable for the user to reduce the image to be made. Therefore, in such a case, it is not selected to reduce the image and make the plate (N in S29). In this case, for example, “If this plate is made as it is, it may be easy to cause a paper discharge jam. ”Is displayed on the display unit 106 (S35), and the stencil printing unit 3 perforates the stencil sheet R with a normal size (1/1 magnification) on the stencil sheet R. Plate making is performed (S25). Then, the stencil printing mechanism unit 5 performs general printing on the printing paper P using the stencil sheet R made by such a general method (S26).
[0062]
As described above, the density of the front end portion of the original image, that is, the density of the portion corresponding to the front end portion in the rotation direction when the stencil sheet R made on the basis of the original image is placed on the plate cylinder 45 is set at the time of printing. In the case where the density of the printing paper P is high enough to cause the phenomenon that the printing paper P sticks to the plate cylinder 45, a blank area of a predetermined area extending over a distance of 10 to 15 mm from the leading edge of the stencil sheet R toward the trailing edge is formed. As is provided, plate making is performed by reducing the image size to be punched in the stencil sheet R. Since the printing paper P does not stick to the blank portion provided at the leading edge of the stencil sheet R in this way at the time of printing, the leading edge of the printed printing paper P is easily separated from the plate cylinder 45. become. Thereby, it is possible to prevent the printing paper P from sticking to the plate cylinder 45, and it is possible to make use of the useful characteristics of the stencil printing apparatus as a simple printing apparatus that performs printing with high printing quality with high efficiency.
[0063]
In addition, when the image size to be punched is reduced as described above, the fact is displayed on the display unit 106 to notify the user in advance, and the image size that the user actually punches based on the display. It is possible to select whether or not to reduce the size before the start of actual plate making. In this way, when performing plate making by reducing the image to be punched, the user can select whether or not such plate making can be executed by informing the user in advance, so that the user can select in an interactive manner. Is also possible.
[0064]
In the second embodiment, the case where the user manually selects whether or not to reduce the size of the document image when the leading edge of the document image has a high density has been described. The determination as to whether or not reduction plate making is possible may be automatically performed by the control unit 100 or the like. That is, for example, in the case of a stencil printing apparatus adopting a stencil printing method that performs image expression by performing binary perforation on the stencil sheet R, the entire image data obtained by reading from the document 2 is included in the entire image data. Calculate the ratio of the number of dots corresponding to the actual perforation out of the total number of dots assumed in the above, and based on this ratio, the original image can be reduced such as a photo, picture, or color illustration It may be automatically discriminated whether there is an image or an image that tends to cause inconvenience when reduced, such as a design drawing or a blank map. For example, if the actual number of dots related to perforation is less than 50%, it is determined that the image is a blueprint or a blank map, and if it is 50% or more, it is an image such as a photograph, picture, or color illustration. It is also possible to use a technique such as discrimination.
[0065]
Note that, based on the ratio of the number of dots related to the actual perforation to the total number of dots assumed in the entire area of one image as described above, the image density in the predetermined area at the leading edge of the document image is predetermined. It is also possible to detect whether or not the density is higher. For example, the original image is reproduced with respect to the total number of dots assumed in a predetermined area at the front end of the original in the image read from the original 2 (that is, the total number of dots when the predetermined area is perforated). In order to do this, the ratio of the number of dots that are actually perforated within the predetermined area at the tip thereof (that is, the number of dots related to actual perforation) is calculated, and the ratio is set as the predetermined density in the above embodiment, for example. If it is 75% or higher, it may be determined as “predetermined density or higher”, or if it is lower than 75%, it may be determined as “lower than predetermined density”.
[0066]
In both the first and second embodiments, at the stage where the document 2 is set on the document setting table 21, one of the four peripheral portions of the document image is the plate cylinder of the stencil sheet R. Although the case where it is already determined whether or not it corresponds to the front end portion in the 45 rotation direction has been described, it is undecided which one side will finally correspond to the front end portion in the rotation direction of the plate cylinder 45 at the document reading stage. In some cases. This is because, for example, when printing on A4 size printing paper P, the shorter width direction is the rotational direction of the plate cylinder 45 than when the plate is placed so that its longitudinal direction matches the rotational direction of the plate cylinder 45. Is used because it is preferable that the stencil sheet R is used so that the length of the stencil sheet R used for the one image can be shortened to save the stencil sheet R. However, in such a case, after the image is read from the document 2 set on the document setting table 21, the orientation of the image may be transposed so that the image is switched in the vertical and horizontal directions. For this reason, if there is a solid region on any one of the four peripheral portions of the original image, one side of the solid may come to the front end in the plate cylinder rotation direction when the image is transposed during plate making. As a result, the printing paper P may stick to the plate cylinder 45 due to this. Therefore, in order to cope with such a case, if there is a solid region on any one of the four peripheral portions of the original image, a blank portion may be provided at the front end of the stencil sheet R in the plate cylinder rotation direction. Good.
[0067]
In both the first and second embodiments, the original image is once read entirely by the original reading unit 1, and then image data of the leading end and the trailing end is extracted from the read image data. In the above description, the image density of these portions is detected. However, when the read document image is sequentially transmitted to the plate making unit 3 for plate making, such an image sensor 31 for reading the document is used. Separately from this, the image density of the predetermined area may be detected by using a dedicated optical sensor or the like for detecting the image density of the predetermined area at the leading edge or the trailing edge of the document image.
[0068]
Further, in the first and second embodiments, when plate making is performed so that a predetermined margin is provided at the leading end of the stencil sheet R, it is possible to effectively prevent the occurrence of a paper discharge jam or the like. Needless to say, the user may be notified by displaying on the display unit or the like.
[0069]
The technique according to the first embodiment and the technique according to the second embodiment may be used together. That is, when the image density at the leading edge of the document 2 is high, the punching start position for the stencil sheet R is shifted over a predetermined distance as shown in the first embodiment. By shifting the leading end portion in this way, the image at the rear end portion of the image is cut over the predetermined distance. However, when it is not desirable to cut the image at the trailing edge as described above, a technique for reducing the entire image to be made as shown in the second embodiment is adopted, and the leading edge of the stencil sheet R is used. In addition, a blank portion may be provided and the image at the rear end portion may not be cut. In many cases, a high-density original image at both the front and rear ends is a photograph or a picture. In such an original, the method of shifting the plate making according to the first embodiment is used. As described in the above-described embodiment, it is desirable to employ the method of reducing the image according to the second embodiment and making a plate. Or, on the other hand, in the case of an original document such as a design drawing that may cause inconvenience if it is reduced, an image to be made by providing a blank portion by shifting it over a predetermined distance as shown in the first embodiment. It is desirable that the magnification of the original is 1/1. As described above, the plate making method according to the first embodiment and the plate making method according to the second embodiment are prepared, and any one of the methods can be selected according to the type or specification of the document. By doing so, it is also possible to use different plate making methods appropriately corresponding to the types and specifications of the originals.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration mainly of a mechanical part of a stencil printing apparatus according to the present invention.
FIG. 2 is a block diagram schematically showing a schematic configuration of a control system in the stencil printing apparatus according to the present invention.
FIG. 3 is a flowchart showing an outline of a series of operations from reading an original to performing printing through plate making in the stencil printing apparatus according to the first embodiment.
FIG. 4 is a flowchart showing the main part of the operation when plate making is started from the rear end side.
FIG. 5 is a flowchart showing an outline of the operation of the stencil printing apparatus according to the second embodiment.
[Explanation of symbols]
1 Document reader
3 Plate making part
5 Stencil printing mechanism
7 Discarding part
9 Paper feeder
11 Paper discharge unit
100 Control unit
101 Image processing unit
102 Concentration detector

Claims (9)

In the plate making method in stencil printing for making the stencil sheet by perforating the unspun stencil sheet based on the original image,
When the image density of a predetermined region in at least one peripheral portion of the four peripheral portions of the original is equal to or higher than a predetermined concentration , a blank portion is provided in a peripheral region of the front end portion of the stencil sheet to perform the plate making. A stencil making method for stencil printing. In the plate making method in stencil printing for making the stencil sheet by perforating the unspun stencil sheet based on the original image,
When the image density of a predetermined area at the leading edge of the original corresponding to the leading edge of the stencil sheet is equal to or higher than a predetermined density , a blank portion is provided in a peripheral area of the leading edge of the stencil sheet to perform the plate making. A stencil making method in stencil printing.   When the image density of a predetermined area at the leading edge of the original corresponding to the leading edge of the stencil sheet is equal to or higher than a predetermined density, an image of the image when punching is performed based on an image of the original with the image density less than the predetermined density. 3. The plate making method in stencil printing according to claim 1, wherein the margin is provided by punching an image corresponding to the image of the document at a magnification lower than the magnification. A plate making means for making a stencil sheet by punching an unperforated stencil sheet based on a document image; and a printing means for printing the printing sheet by winding the stencil sheet around a plate cylinder. In a stencil printing machine having
Detection means for detecting that the image density of a predetermined area in at least one peripheral part of the four peripheral parts of the document is equal to or higher than the predetermined density is detected, and the plate making means is detected to be higher than the predetermined density. In this case, the stencil printing apparatus is characterized in that the stencil printing is performed by providing a margin part in a region around the front end of the stencil sheet. A plate making means for making a stencil sheet by punching an unperforated stencil sheet based on an image of an original; and a printing means for printing the printing sheet by winding the stencil sheet around a plate cylinder In a stencil printing machine having
Detection means for detecting that the image density of a predetermined area at the front end portion of the original corresponding to the front end portion of the stencil sheet is equal to or higher than a predetermined density, and the plate making means is detected to be higher than the predetermined density. In this case, the stencil printing apparatus is characterized in that the stencil printing is performed by providing a blank portion in a region around the leading end of the stencil sheet.   The plate making means performs punching of an image corresponding to the image of the document at a magnification lower than the magnification of the image when punching based on the image of the document with the image density less than a predetermined density, thereby causing the margin portion The stencil printing apparatus according to claim 4, wherein the stencil printing apparatus is provided. A plate making means for making a stencil sheet by punching an unperforated stencil sheet based on an image of an original; and a printing means for printing the printing sheet by winding the stencil sheet around a plate cylinder In a stencil printing machine having
The image density of the predetermined area at one end of the both ends of the original corresponding to the leading edge and the trailing edge of the stencil sheet is equal to or higher than the predetermined density, and the image density of the predetermined area at the other edge is predetermined. Equipped with detection means for detecting that the concentration is less than
When the plate making means detects that the image density of the predetermined area at the other end is lower than the predetermined density, the end lower than the predetermined density corresponds to the leading end of the stencil sheet. The stencil printing apparatus is characterized in that the plate making is performed as described above.   In the case where the margin portion is provided, it is further provided with notifying means for notifying at least one of the visual information and the audio information that the margin portion is provided on the image printed on the printing paper. The stencil printing apparatus according to claim 4, 5 or 7.   When the margin is provided, the image corresponding to the image of the original is punched at a lower magnification than the image magnification when punching based on that fact and the image of the original whose image density is less than the predetermined density. Informing means for informing at least one of visual information and audio information of the fact that the image printed on the printing paper is reduced or the like is further provided. The stencil printing apparatus according to claim 6.

Images