JP2001158076A - Plate making method in stencil printing and stencil printing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plate making method in stencil printing and a stencil printing device, in which printing of high printing quality is performed with high efficiency by preventing generation of such phenomena that a printing paper is stuck to a plate cylinder. SOLUTION: When a density detection part 102 detects that density of an image in a prescribed range of the tip part of a manuscript image is not less than prescribed density, a plate making part performs plate making for a base paper R of the stencil printing so as to provide a margin part in a range of a prescribed distance from the tip part in the direction of rotation to the rear part when the base paper R of the stencil printing is stuck to the plate cylinder. A printing form P is easily detached from the plate cylinder 45 by elastic properties of itself by means of the margin part provided in the tip part of the base paper R of the stencil printing. Also, a separation click 81 is easily entered between the printing form P and the plate cylinder 45 and the printing form P, on which ink is transferred, is surely separated from the plate cylinder 45.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stencil printing method and a stencil printing machine for stencil printing, and more particularly, to a stencil printing method for making a stencil sheet by perforating an unperforated stencil sheet, and the stencil sheet thus formed. The present invention relates to a stencil printing apparatus that prints on printing paper by winding a stencil around a printing drum.

[0002]

2. Description of the Related Art In a conventional stencil printing apparatus, generally, an image of a document is read by an image sensor or the like, and based on information of the read image, an unperforated stencil sheet is formed by a stencil making means such as a thermal head. By performing perforation, so-called stencil making is performed, the stencil sheet having the stencil made is wound around a plate cylinder, and printing is performed by transferring printing ink by applying printing pressure to printing paper while rotating the plate cylinder in a predetermined direction. Are doing.

[0003] However, when the stencil sheet having been made stencil is wound around the plate cylinder and rotated, the stencil sheet bleeds out of the stencil sheet and is transferred to the printing sheet. The printing paper is no longer separated from the plate cylinder due to an increase in the attraction force with the plate cylinder, and the printed printing paper is wrapped around the plate cylinder, and is then supplied to the plate cylinder following the wrapped printing paper. In some cases, the printing paper to be printed causes a so-called paper discharge jam, or the stencil sheet is damaged due to such a paper discharge jam.

[0004] Therefore, by using a device called a separation claw, or in addition to the above, by blowing air from the tip of the separation claw, the printing paper which is fed out while the ink is transferred by the plate cylinder is converted into the printing paper. They had to be separated from the plate cylinder.

[0005]

However, when a high printing density portion such as a so-called solid portion exists at the leading end of the stencil sheet in the rotation direction, the adhesive strength of a large amount of ink at that portion is reduced. Due to this, the attraction force between the printing paper and the plate cylinder in that part increases, and the part sticks to the plate cylinder, so even if the above-described separation claw or air ejection is used, The printed printing paper cannot be securely separated from the leading end of the printing paper, and the printed printing paper may wrap around the plate cylinder. With paper
There has been a problem of causing a so-called paper discharge jam, and a problem that the stencil sheet may sometimes be damaged due to such a paper discharge jam.

In addition, when the leading end of the stencil sheet in the rotation direction is stuck to the plate cylinder, the leading end of the printing paper is wound around the surface of the plate cylinder (that is, around the periphery thereof) by the separating claw. To remove from the stencil sheet)
The leading edge of the separation claw must be inserted between the printing paper and the stencil sheet strongly adhered from the leading edge.If the separation claw is brought close to the surface of the stencil sheet, The probability that the tip of the separation claw contacts the surface of the stencil paper or the printing surface of the printing paper becomes extremely high,
There has been a problem that printing defects such as separation claw marks may occur on (in a printed image of) printing paper, or the surface of the stencil sheet may be damaged, resulting in reduced printing quality thereafter.

[0007] In addition to problems such as mechanical printing defects and breakage of the stencil sheet caused by the separation claw, the leading end of the printing paper adhered to the stencil sheet on the surface of the plate cylinder has a strong force. In the technique of separating the leading edge of the printing paper from the surface of the plate cylinder by blowing strong air, the printing paper is strongly adhered to the plate cylinder at the solid part and the printing paper cannot be separated even if strong air is blown In some cases, however, in such a case, the back surface of the printing paper is pressed against the surface of the plate cylinder with strong air, which may have an adverse effect. Also, even if you can somehow pull the printing paper apart,
Since the printing surface of the solid portion that has just been printed is particularly hard to dry, it is often in a semi-dry state, and the semi-dry ink is blown off by strong air and causes dripping, flow, or bleeding. Therefore, there is a problem that a printing failure or image deterioration may be induced.

If the problem caused by the phenomenon that such printing paper sticks to the plate cylinder cannot be solved,
As described above, the paper jam and the damage of the stencil sheet, the occurrence of separation claw marks, and the like are caused, and the advantage of performing high-quality printing, which is an extremely useful characteristic of a stencil printing apparatus as a simple printing apparatus, with high efficiency. Therefore, it has been desired to eliminate such a phenomenon that the printing paper sticks to the plate cylinder as described above.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and eliminates the occurrence of a phenomenon in which printing paper is stuck to a plate cylinder, thereby performing high-quality printing with high efficiency. It is an object of the present invention to realize a stencil printing method and a stencil printing machine that can make use of useful characteristics of a stencil printing machine as an apparatus.

[0010]

A stencil printing method according to the present invention is a stencil printing method for stencil making an unperforated stencil based on an image of an original. When the image density of a predetermined region in at least one of the four peripheral portions of the document 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 to perform the stencil making. It is characterized by performing.

The stencil printing method of stencil printing according to the present invention, wherein the stencil printing is performed by punching an unperforated stencil based on an image of a document. When the image density of a predetermined region 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 stencil is provided by providing a blank space over a predetermined distance from the leading edge of the stencil paper. It is characterized by the following.

Here, if the image density of a predetermined area at the leading end of the original corresponding to the leading end of the stencil sheet is higher than a predetermined density, perforation is performed based on the image of the original having the image density lower than the predetermined density. The margin portion may be provided by piercing an image corresponding to the image of the document at a magnification lower than the magnification of the image to be performed.

The stencil printing apparatus of the present invention is a stencil printing machine for perforating an unperforated stencil sheet based on an image of an original to make the stencil sheet, and winding the stencil sheet around a plate cylinder. A stencil printing apparatus having printing means for performing printing on printing paper, comprising detecting means for detecting that the image density of a predetermined area in at least one of the four peripheral parts of the document is equal to or higher than a predetermined density. When the stencil making means detects that the density is equal to or higher than the predetermined density, the stencil sheet is formed by providing a blank space over a predetermined distance from the leading end of the stencil sheet.

Further, the stencil printing apparatus of the present invention comprises a stencil making means for making a stencil based on an image of an original on an unperforated stencil, and winding the stencil on a printing drum. A stencil printing apparatus having a printing means for performing printing on a printing paper by rotating the stencil sheet, detecting that an image density of a predetermined area at a front end of the document corresponding to a front end of the stencil sheet is equal to or higher than a predetermined density. Means for making a stencil by providing a blank portion over a predetermined distance from the leading end of the stencil sheet when the stencil means is detected to be at least the predetermined density. It is characterized by.

Further, the plate making means perforates an image corresponding to the image of the document at a lower magnification than the image magnification when perforating based on the image of the document having the image density lower than a predetermined density. Accordingly, the margin portion may be provided.

Further, a perforating means for perforating an unperforated stencil sheet based on an image of a document to make a stencil sheet, and printing the stencil sheet on a printing drum by winding the stencil sheet around a printing drum. A stencil printing apparatus having a stencil printing device, wherein the image density of a predetermined area at one end of both ends of the document corresponding to the front end and the rear end of the stencil sheet is equal to or higher than a predetermined density, and Detecting means for detecting that the image density of the predetermined area at the end of the predetermined area is lower than the predetermined density, wherein the plate making means detects that the image density of the predetermined area at the other end is lower than the predetermined density. In such a case, the stencil making is performed such that the end having a density lower than the predetermined density corresponds to the leading end of the stencil sheet.

In the case where the margin is provided, a notifying means for notifying at least one of visual information and audio information may be further provided.

In such a case, when making a plate by reducing the magnification of the image, that is, making the image substantially smaller than the normal case, the fact and the image density are lower than the predetermined density At least one of the effect of perforating an image corresponding to the image of the document at a magnification lower than the image magnification when perforating based on the image of the document and the effect of reducing the image printed on the printing paper One may be further provided with a notifying means for notifying with visual information or audio information.

In other words, according to the present invention, if there is a high-density solid portion on any one of the four peripheral portions (four peripheral sides) of a document having a generally rectangular outer shape, the printing paper is placed on the plate cylinder during printing. It is determined that the sticking phenomenon is highly likely to occur, and a margin is provided at the leading end in the rotation direction of the stencil sheet. Here, in the document reading stage, it may be undecided which one of the four peripheral portions of the document will eventually be the leading end in the rotation direction of the plate cylinder. In either case, a phenomenon may occur in which the printing paper sticks to the plate cylinder. Therefore, a margin is provided at the leading end of the stencil sheet.

Alternatively, which one of the four peripheral portions of the original corresponds to the leading edge of the stencil sheet is often predetermined (or known) in advance. The image density of one side on the original corresponding to the leading edge is checked, and when 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, A margin is provided at the leading end in the rotation direction when the stencil sheet is applied to the plate cylinder.

The size of the margin may be set to an interval that allows the printing paper to be surely separated from the plate cylinder by a separation claw or blowing of air. Alternatively, the interval may be set such that the printed printing paper can be separated from the margin by the weight of the printing paper, the elasticity of the printing paper itself, the drying of the ink, and the like. The more detailed setting of the margin varies depending on various conditions such as the setting of the separation claw, the flow rate of the air, the elasticity of the printing paper, the viscosity of the ink, and the drying time. do it.

In providing the margin, it is effective to shift the perforation start position from the front end to the rear end. However, in addition to this, the size of the image to be made on the stencil paper, A method of reducing the perforated area smaller than the normal perforated area of the stencil sheet is also a preferable embodiment.

Further, shifting or reducing the position of an image to be made on a stencil sheet in order to provide the above-mentioned margins means that an image to be printed on printing paper by the stencil sheet is made as described above. Since it is shifted or reduced, it is desirable to notify the user in advance of that.

Further, by providing a means for allowing the user to select whether or not to provide the above-mentioned margin portion, the user can make a stencil sheet based on information notified before the start of printing. Alternatively, it may be determined whether or not the above-described margin may be provided on the printing paper, and the determination result may be selected.

That is, when a 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 Even if the user chooses to provide a margin at the tip, there is no practical inconvenience, and the user may select it. Alternatively, when a margin portion is provided by reducing an image to be printed on printing paper, for example, when a user performs printing using a precise 1/1 design drawing as a document or printing using a 1 / 50,000 map as a document, In this case, it is desirable that an 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 allowed to select 1/1 printing without intentionally selecting reduced printing for providing a margin. In addition, when the user performs printing based on a general home-use photographic original or illustration original, there is no practical problem even if the print image is slightly reduced. This is preferable because the winding of the paper can be eliminated. Rather, in this case, a margin can be provided around the entire periphery of the printed image, and as a result, the image layout on the printing paper can be made to look more natural, which is preferable.

[0026]

According to the present invention, in a stencil printing method and a stencil printing machine, a solid portion having a high density is formed so that the leading end of the stencil sheet tends to stick to the plate cylinder. If it is present at the leading edge, it is detected by the detecting means, and a margin is intentionally provided at the leading end of such stencil paper to eliminate the occurrence of the phenomenon that the printing paper sticks to the plate cylinder. In addition, it is possible to take advantage of the extremely useful characteristics of the stencil printing apparatus as a simple printing apparatus for performing high-quality printing with high efficiency.

[0027]

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

(Embodiment 1) FIG. 1 is a diagram showing a schematic configuration of mainly a mechanical 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.

This stencil printing apparatus has a stencil printing function with a stencil making function of performing perforation on an unperforated stencil sheet R based on an image read from the manuscript 2 (hereinafter also referred to as a manuscript image). A document reading unit 1, a stencil making unit 3, a stencil printing mechanism 5, a stencil discharging unit 7,
The control unit 100 includes a sheet feeding unit 9, a sheet discharging unit 11, an image processing unit 101, a density detecting unit 102, and a control unit 100 that controls a mechanical operation, a data processing operation, and the like of each unit.

Here, as the correspondence relationship with each means in each claim, the plate making unit 3 and the control unit 100 for controlling the plate making unit 3 are described.
It goes without saying that the stencil printing mechanism unit 5 and the control unit 100 for controlling the stencil printing unit correspond to the printing unit, and the density detecting unit 102 and the control unit 100 for controlling the stencil printing unit correspond to the detecting unit. .

More specifically, the original reading unit 1
An original set table 21 using a tempered glass plate or the like on which an image is placed, and an image sensor 31 that reads an image of the original 2 and converts the image information into an electric signal carrying the image information.
An image sensor moving motor mechanism 32 for mechanically scanning the image sensor 31 with respect to the document 2, and a reference position sensor 3 for detecting a moving position of the image sensor 31
3 is provided.

There are mainly two types of reading methods (reading method and apparatus configuration) of the document image in the document reading section 1. That is, first, one document image is read, and is read as a set of image data in the RAM (R
The thermal head 35 is temporarily stored in a storage means such as a cache memory (cache memory) using an random access memory (105), and the image data is read from the storage means in batches when the stencil sheet R is made. There is a method that is used to drive the. Second, the image sensor 31
There is a method in which information of a document image read by the A / D converter or data processing is directly and time-sequentially transmitted to the thermal head 35 without going through storage in the storage means. In the case of the first method, a storage means such as the RAM 105 for temporarily storing the data of the read image is required. Since perforation can be performed, the density of both the leading edge and the trailing edge of the image can be determined.
Although there is an advantage that detection can be performed based on the read image data, a time lag occurs in which the punching operation cannot be performed while the document 2 is being read. In the case of the second method, image data obtained by reading from the original 2 is immediately transferred to the thermal head 3.
5 and the punching operation can be executed, so that there is an advantage that a time lag hardly occurs between the image data reading operation and the punching operation. Can be detected if the position is read first, but it is practically impossible to detect the density at the rear end of the document image until the perforation is almost completed. Therefore, in consideration of such points, it is only necessary to appropriately determine which of the above-described methods is desirably adopted as the document reading unit 1.

The stencil making section 3 includes a thermal head 35, a main part of which is formed so as to pierce the stencil sheet R in accordance with the original image, a platen roller 37, a pair of stencil conveying rollers, and a platen roller. It comprises a stepping motor 41 for rotating and driving a pair of base paper transport rollers 39a and 39b and a base paper cutter 43. When the stencil sheet R stored in the roll form is pulled out, the stencil section 3 carries image information read from the original 2 by the original reading section 1 while scanning the stencil sheet R in the so-called sub-scanning direction. The stencil sheet R is perforated by the thermal head 35 based on the image data obtained from the electric signal, thereby performing the stencil making. At this time, the platen roller 37 plays a role of pressing the stencil sheet R against the thermal head 35. The perforated stencil sheet R is fed out by a pair of stencil conveying rollers 39a and 39b, and its rear end is cut by a stencil cutter 43 so as to have a size suitable for the size of the printing paper P.

The stencil printing mechanism unit 5 includes a cylindrical plate cylinder 45 capable of leaching ink and rotating about a rotation axis;
An ink supply mechanism 53 having a squeegee roller 49 and a doctor roller 51 disposed inside the plate cylinder 45; a plate cylinder 47; A main motor 55 for rotating the roller 45 in a predetermined direction; a press roller 59 for applying printing pressure with the printing drum P together with the plate cylinder 45; and a press control mechanism 61 for controlling the vertical movement of the press roller 59. I have. At the end of the plate cylinder 45, a magnet piece 85 is attached. When the plate cylinder 45 reaches the plate start rotation position, a plate start position sensor 87 for detecting the rotation 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 plate start position sensor 87 described above is provided.
The rotational position of the plate cylinder 45 can be quantitatively detected based on the print start position of the plate cylinder 45 based on the output.

The stencil sheet discharging section 7 accommodates the stencil sheet S, which is a stencil sheet S after the stencil sheet S that has been made and used is peeled off from the plate cylinder 45 and discharged. Plate discharge box 63 and plate discharge roller pair 6
And a transmission type plate discharge sensor 69 for detecting whether or not the stencil sheet S has passed at the position 5.

The paper feeding section 9 is provided with a paper feeding table 71 on which the printing paper P is placed and which is moved up and down by a vertical movement mechanism (not shown), and a printing paper P placed on the paper feeding table 71. A pickup roller 73 for taking out each sheet, a paper feed clutch 75 for interrupting a driving force transmitted from the main motor 55 to the pickup roller 73, and a printing paper P for transferring the printing paper P in synchronization with the rotation of the plate cylinder 45. Paper transport roller pair 77 to be sent out between the roller and the press roller 59, and the paper transport roller pair 7
And a transmission type paper sensor 79 for detecting the presence or absence of the printing paper P at the position 7.

The paper discharge unit 11 includes a separation claw 81 for separating the printed printing paper P from the plate cylinder 45, and a paper discharge table 83 on which the printed printing paper P is placed in a stacked manner. I have. 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.

The control unit 100 includes the original reading unit 1, the stencil making unit 3, the stencil printing mechanism unit 5, the stencil discharging unit 7, the paper feeding unit 9, the paper discharging unit 11, the image processing unit 101 and the density detecting unit 102.
Each operation is controlled while synchronizing as necessary. Further, the control unit 100 executes a control function based on a system program stored in advance in the ROM 103 or the like, that is, a control circuit 104 using a so-called microcomputer (microcomputer) or the like, and various types of operations related to the operation of the stencil printing apparatus. A display unit 106 for displaying information;
Prepress start key, print start key, print mode setting key, numeric keypad used to input the number of prints, reset key, job emergency stop key, etc. (all not shown) Selection of operation mode of normal stencil printing machine Operation unit 1 provided with an operation panel (not shown) for inputting a command such as a command for selecting whether to shift the plate making start position or not.
07.

When the density detector 102 detects that the density of the leading end of the document 2 is equal to or higher than the predetermined density, the controller 100 extends a predetermined distance from the leading end of the plate cylinder 45 in the rotation direction. In order to perform stencil making so that a margin portion is provided at the leading end of the stencil sheet R, the thermal head 35 is started so as to start piercing from a position shifted rearward in the rotation direction of the plate cylinder 45 from a normal piercing start position. It controls the driving. In other words, perforation is performed in a region shifted from the normal perforation region in the case where the density of the leading end of the document 2 is lower than the predetermined density toward the rear by the margin. As a method of executing such a shift of the drilling start position (shifting of the drilling region), there are mainly two more specific methods. That is, first, when the density of the leading end of the document 2 is equal to or higher than the predetermined density, the leading end of the stencil sheet R is moved by the pair of stencil conveying rollers 39a and 39b at the time when the perforation by the thermal head 35 is started. There is a so-called mechanical method in which a predetermined distance is extended beyond the 35 heating element arrays, and the margin is obtained by extending the predetermined distance. Secondly, the mechanical feed-out position of the leading end of the stencil sheet R at the start timing of the perforation by the thermal head 35 is the same as in the normal case (that is, when the density of the leading end of the document 2 is lower than the predetermined density). On the other hand, there is a so-called image data method of adding dummy blank data that can provide the above-mentioned blank portion to image data input to the thermal head 35. It goes without saying that either of these two methods may be used. However, in any case, the perforation corresponding to the image at the rear end deviates (protrudes) backward from the original perforated area. As a result, the ink exuding from the stencil printing paper remains untransferred to the printing paper P, and the plate cylinder 45 and its surroundings are soiled with ink, and the subsequent printing paper P becomes stained with the untransferred ink. When the stencil sheet R is cut to a normal size, the rear end portion of the stencil sheet R which protrudes from the normal perforation area is cut off halfway, and is placed at the leading end of the stencil sheet R to be stenciled next time. There may be inconveniences such as the presence of extra perforations before. Therefore, in the case where such a problem is highly likely to occur, when the punching start position of the leading end of the stencil sheet R is shifted, the punching of the protruding portion of the rear end is also not performed. It is desirable to take such measures. For example, in the case of the first method, the thermal head 35 is used to perform the perforation more than usual so that the rear end is not perforated over the same distance as the predetermined distance of the front end. It is only necessary to forcibly stop the vehicle slightly earlier. Alternatively, in the case of the second method, a method is used in which image data having a data amount similar to that of the margin data added to provide a margin at the leading end is deleted from the image data at the trailing end. Good.

However, there is a possibility that the perforated area is shifted in order to provide such a margin, or a margin is formed at the leading end of the image printed on the printing paper P by shifting the perforated area. Is displayed on the display unit, and only when the user selects to shift the perforated area in such plate making (the user inputs an instruction to that effect to the operation unit), Plate making in which such a perforated area is shifted is performed. Alternatively, when the user does not select such a plate making that shifts the perforated area (the user inputs an instruction to that effect to the operation unit), the blank area is not shifted by shifting the perforated area, and the normal operation is performed. A general plate making is performed on a normal perforation area starting from a perforation start position. Further, when both the leading edge and the trailing edge of the original have a higher density than the predetermined density, the display unit informs the user that the image of the trailing edge of the high density will be cut somewhat. It may be displayed.

The image processing unit 101 digitizes an electric 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. And thermal head 3
5 to obtain image data for performing the punching operation.

The density detecting section 102 detects whether or not the density of a predetermined area at the leading end of the original image read by the original reading section 1 is equal to or higher than the predetermined density. Also detects whether the density is equal to or higher than a predetermined density. That is, in general, the outer shape of the document 2 is often a rectangle such as a rectangle, and when the document 2 is set on the document set table 21, one of the four sides of the peripheral portion of the document 2 In many cases, it is determined whether or not it corresponds to the leading end of the base paper R (the leading end in the rotation direction in which the printing is performed on the plate cylinder 45 and rotated). 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 high density equal to or higher than a predetermined density. Is performed at the leading edge of the printing paper P, the probability that the disadvantage that the printing paper P sticks to the plate cylinder 45 increases, so that in order to prevent the occurrence of such a disadvantageous phenomenon, first, It detects that the leading end of the document image has a predetermined density or higher. Further, in the present embodiment, it is also detected whether or not the rear end of the original image has a density higher than a predetermined density.

There are mainly two methods for detecting the density of the leading edge and the trailing edge of such an original image. First, a predetermined area corresponding to the leading end of a document image is determined 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, and the like. There is a method of detecting the density of an image. Second, in addition to the above-described image sensor 31, a density detection sensor or the like (not shown) dedicated to density detection in a predetermined area at the leading end of the document image is provided, and the document 2 is set on the document set table 21. At the stage, there is a method of performing density detection without depending on (independently) reading of a document image by the image sensor 31. That is, in the first method, the existing image sensor 31 and image processing unit 101 can be diverted as a part of the density detection unit 102, so that it is not necessary to further add hardware for density detection and the like. There is an advantage that the detection unit 102 can be easily realized by, for example, software implementation, but it is practical to detect the density at the leading end of the document image until the image is read from the document 2 and the image data is obtained. Impossible. If it does not matter for practical use, the first method may be adopted. In the second method, separately from the existing image sensor 31 and the image processing unit 101,
Hardware such as a reflection type optical sensor for detecting image density and a density measuring circuit (both not shown) must be added, but in practice, such additional components are often not so complicated, and There is an advantage that the density of the leading edge of the document image can be immediately detected when the document 2 is set before the process of reading the document image and obtaining the image data.

As for the above-mentioned first detection method, there are two more methods. 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 data of the document image used for plate making is obtained. In such a case, when image data is obtained by the pre-scan, there is a method of detecting the density of the front end portion and the rear end portion of the image. Secondly, when a document image is read, the image data is sequentially sent to the thermal head 35 to perform perforation, and reading is started from the leading end of the image. , And the density of the image read over a predetermined area at the tip is detected. It goes without saying that these methods may be appropriately used in consideration of their respective characteristics.

The predetermined density and the predetermined area include the own weight and elasticity of the printing paper P, the viscosity and drying time of the ink, the setting of the separation claw 81, and the air blown from the tip of the separation claw 81. Since the suitable setting varies depending on various conditions such as the flow rate, it may be appropriately set in accordance with each of those factors. For example, in the case of standard plain paper such as general A4 size, an area extending from a leading edge to a distance of 10 mm to 25 mm is defined as the predetermined area, and a completely solid state having the highest density is defined as 100%. %, The solid state of 75% high density may be set to the predetermined density. The setting of the predetermined area and the predetermined density is merely an example, and as described above, the specification of the printing paper P and the 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.

Next, an outline of a series of operations from the original reading step to the printing step through the stencil making step in the stencil printing apparatus of the first embodiment having the main parts configured as described above will be described. FIG. 3 is a flowchart illustrating an outline of a series of operations from reading a document to performing printing through plate making in the stencil printing apparatus according to the first embodiment.

The original 2 is set on the original set table 21,
The operation unit is operated by the user, and the reading operation of the document image in the document reading unit 1 is started (S1). The electric signal carrying the read document image information is further transmitted to the image processing unit 101, subjected to A / D conversion and data processing, and stored as image data in a storage unit such as a RAM 105 for an image memory. Is temporarily stored (stored) (S2). By extracting and examining data of a portion corresponding to a predetermined region at the leading end of the document image from the image data obtained at this time (S3), a predetermined region at the leading end of the document image (the document 2 in the present embodiment) is obtained. Is a solid image having a density higher than a predetermined density (75% or more of the maximum density in this embodiment) in a range defined by a distance extending from 10 mm to 15 mm from the front end to the rear end of the image. Is detected by the density detection unit 102 (S4). At this time, if the density is lower than the predetermined density (N in S4), the probability of occurrence of the sticking phenomenon of the printing paper P to the plate cylinder 45 is low. General plate making such as perforation is performed (S5). Then, the stencil printing mechanism section 5 performs general printing using the stencil sheet R made by such a general method, for example, A
The process is performed on a printing paper P such as a standard plain paper such as a 4-size (S6).

However, if the density is higher than the predetermined density (Y in S4), the image is further moved to the rear end of the original image by 10 to 15 m.
The density detection unit 102 detects whether or not a predetermined area such as an area over m is a solid image having a density higher than the predetermined density (S7). At this time, if the trailing edge of the original image is lower than the predetermined density (N in S7), a display indicating that the leading edge of the original 2 is slightly shifted from the normal case to perform plate making, or further such plate making. Is displayed on the screen of the display unit 106 using a display device such as a liquid crystal display panel, for example, indicating that the printing area on the printing paper P is slightly shifted from the normal case by executing the shifting. For example, it is displayed in Japanese notation in which kanji and hiragana are combined (S8). Then, it is determined whether the perforating start position (that is, perforating area) may be actually shifted backward by a predetermined distance from the normal perforating start position on the stencil sheet R for a predetermined distance, and whether or not the perforating may be performed. The user makes a selection (S9). At this time, if it is selected that the plate making may be performed shifted (Y in S9), the plate making is performed by the plate making unit 3 with the leading end shifted over a predetermined distance (S1).
0). The stencil printing mechanism unit 5 executes printing using the stencil sheet R produced by making the perforated area more positively than usual by a predetermined distance (S11).

Alternatively, at this time, if it is not selected by the user to shift the plate making (N in S9),
For example, after a message stating that "if the original is made as it is, the paper discharge jam may easily occur" is displayed on the display unit 106 (S15), the plate making unit 3 starts from a normal position with respect to the stencil sheet R. A perforation is performed to perform general plate making (S5). Then, the stencil printing mechanism unit 5 executes general printing on the printing paper P using the stencil sheet R made by such a general method (S6).

On the other hand, if the trailing edge of the original image is equal to or higher than the predetermined density in S7 (Y in S7), the effect that the leading edge of the original 2 is shifted from the normal case to perform plate making or the printing paper P The display unit 106 displays that the upper print area is slightly shifted from the normal case and that the image at the rear end is cut over a short distance (S12). And based on such an indication,
The user decides whether or not a slight margin may be provided at the leading end of the image to be printed at that time (S13), and whether or not the trailing end image may be slightly cut at the same time (S1).
4), if it is determined that there is no problem in both (Y in S13 to Y in S14), when a command to execute the instruction is input via the operation unit, the tip is set to a predetermined value. Is performed by the plate making section 3 (S10). Then, the stencil printing mechanism unit 5 executes printing using the stencil sheet R thus made (S11).

However, if it is not preferable for the user to provide a slight margin at the leading end of the image to be printed (N in S13), or the image at the trailing end may be slightly cut for the user. In an unfavorable case (N in S14), when the user inputs a command not to select the plate making, the user is prompted, "If the original is made as it is, a paper discharge jam may easily occur. Display section 1
06 (S15), the stencil making unit 3 executes a general stencil making such that the stencil making unit 3 starts piercing from a general position and pierces a normal area for the stencil sheet R (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).

As described above, the density of the leading end of the original image, that is, the density of the portion corresponding to the leading end in the rotation direction when the stencil sheet R made based on the original image is placed on the plate cylinder 45, is When the density is high enough to easily cause the phenomenon that the printing paper P sticks to the plate cylinder 45 during printing, a predetermined distance such as 10 to 15 mm from the leading end to the trailing end of the stencil sheet R is used. The stencil making is performed by shifting the starting position of the perforation on the stencil sheet R so as to provide a blank portion extending over the stencil sheet R. As described above, since the printing paper P does not stick to the blank portion provided at the leading end of the stencil sheet R at the time of printing, the printed printing paper P is printed so that the leading end of the 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 useful characteristics of the stencil printing apparatus as a simple printing apparatus for performing high-quality printing with high efficiency. Moreover, the stencil paper R
By providing a margin at the leading end of the plate cylinder 45, a margin where the ink is not transferred is provided at the leading end of the plate cylinder 45 in the rotation direction in the image printed on the printing paper P. Since the sheet is easily separated from the curved surface by the elasticity of the sheet, the separation claw 81 easily enters the separated portion. Therefore, the separation claw 81 does not need to be brought close to the plate cylinder 45 so as to come into contact with the plate cylinder 45, and a problem such as a printing failure such as a conventional separation claw mark or a problem of damage to the stencil sheet R due to the contact of the separation claw 81, etc. Can be eliminated.
In addition, since the ink is not transferred to the margin at such a front end portion, even if air is strongly blown from the front end of the separation claw 81 to the portion, the ink does not flow down due to the air. In addition, it is possible to prevent the printing quality P and the occurrence of print defects due to the ink flow phenomenon, and to reliably print the printing paper P on the plate cylinder 4.
5 can be pulled away.

In addition, in the case where the perforation position is shifted as described above, the fact is notified to the user in advance by, for example, displaying it on the display section 106, and the user actually determines the perforation position based on the display. Whether or not to perform the shifting can be selected before the actual plate making is started. Furthermore, if the rear end of the original image is higher than the predetermined density, the rear end image may be cut by at least that much when the front end is shifted as described above. The user can be notified in advance by displaying the fact on the display unit 106 or the like, so that the user can select whether or not to do so before starting the actual plate making. As described above, by notifying the user in advance of starting the plate making in which the perforated area is shifted, the user can select whether or not to execute the plate making in which the perforated area is shifted in an interactive manner. It becomes possible.

In the first embodiment, the case where the density of both the leading edge and the trailing edge of the document image is detected has been described. However, the density detection of the trailing edge and the display of the detection result are omitted. Then, the density of only the leading end of the document image is detected, and if the leading end has a high density equal to or higher than the predetermined density, this fact is displayed, and a margin is provided when the user selects it. The plate making may be performed in advance.
That is, S7, S12,
The process of detecting or displaying the image density at the rear end of the original 2 as shown in S13 and S14 is omitted, and
May directly proceed to the process of S8.

Alternatively, in the first embodiment,
If it is detected that the leading end of the document image has a high density equal to or higher than the predetermined density and the rear end has a low density lower than the predetermined density (Y in S4 and N in S7), the above-described flowchart is used. Instead of S8 to S11 described above, plate-making may be started from the rear end of the low-density document image.
The stencil sheet R can also be formed by performing stencil making so that the rear end of the original image having the low density corresponds to the leading end in the rotation direction when the stencil sheet R is applied to the plate cylinder 45. It is possible to prevent the printing paper P from sticking to the leading end in the rotation direction. However, when printing is performed using the stencil sheet R made in such a manner, the top and bottom (or left and right) of the original document image and the top and bottom (or left and right) of the printed image are reversed. For example, when the user binds (binds) printing paper P after printing using a sorter, it is inconvenient because only that page is partially different from the other pages in the opposite direction. That is,
In such a case, as shown in an example in the flowchart of FIG. 4, for example, a message such as "Do you want to start plate making from the rear end side?" That fact is notified (S16). If the user selects the stencil sheet R (Yes in S17), the stencil making section 3 performs perforation (stencil making) on the stencil sheet R from the rear end of the original image (S18). The stencil printing mechanism unit 5 executes printing using R (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 in S17), Plate making part 3
Performs a general stencil making such that a normal area is perforated with respect to the stencil R (S5), and the stencil printing mechanism unit 5 uses the stencil R made by such a general method. A proper printing is executed (S6). In this manner, when the rear end of the original image has a low density, the stencil making is performed so that the image of the low density rear end is located at the front end in the rotation direction of the stencil sheet R. Thus, the phenomenon that the leading end of the printing paper P sticks to the plate cylinder 45 can be eliminated.

(Embodiment 2) FIG. 5 is a flowchart showing an outline of the operation of the stencil printing apparatus of the second embodiment. In the second embodiment, in order to provide the same margin as the first embodiment at the leading end of the stencil sheet R, the stencil start position is not shifted to perform stencil making, and the entire perforated area is generally formed. It is characterized in that it is reduced more than usual in the case of a plate making. In other respects, a method substantially similar to that of the first embodiment is employed.

However, in the second embodiment, the size of the image to be printed when the printing is performed using the stencil sheet R made by making the entire perforated area smaller than in the case of general stencil making is generally smaller. Although the size of the image is reduced as compared with an image printed with a typical 1: 1 setting, this may not be preferable for the user. For example, when the user performs printing using a precise 1/1 design drawing as a document or printing using a map such as a 1 / 50,000 map as a document,
It is often desirable that an image finally obtained by printing has a size (magnification) corresponding to 1: 1 with respect to the image of the original. Therefore, in such a case, it is desirable that the user can select plate making and printing at a 1/1 magnification (actual magnification) without intentionally selecting reduced plate making and reduced printing for providing a margin. become. On the other hand, when the user performs printing based on a general home-use photographic original or illustration original, there is no practical problem even if the print image is slightly reduced. This is preferable because the winding of the printing paper P around the printed paper 45 can be eliminated. In this case, if a margin can be provided around the entire periphery of the printed image, the image layout on the printing paper P is consequently reduced. It can be said that it is preferable because it can be made to look more natural. For this reason, it is desirable that the user be able to select a stencil whose image has been reduced based on the type of document or the purpose of use of the printed material. The main feature of the second embodiment is a technique including the ability to select a plate making in which such an image is reduced. Therefore, in the description of the second embodiment, in order to simplify the description, the same parts and operations as those in the first embodiment are not described in detail, and are different from the first embodiment. Among the points, the following is a detailed description focusing on the step of making an image by reducing the size of an image more than in a normal case.

In the stencil printing apparatus according to the second embodiment,
When the density detection unit 102 detects that the density of the leading end of the original image is higher than or equal to a predetermined density,
The control unit 100 automatically controls the plate making operation of the plate making unit 3 to pierce an image smaller than the size of the image pierced by the normal stencil making, thereby removing the same margin as in the first embodiment. It is provided at the leading end of the stencil sheet R.

That is, first, the original 2 is placed on the original set table 21.
Is set, and the operation unit is operated by the user, and the reading operation of the document image in the document reading unit 1 is started (S21). The electric signal carrying the information of the document image read here 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 data of a portion corresponding to a predetermined region at the leading end of the document image from the image data obtained at this time (S2
3) A predetermined area at the leading end of the original image (in this embodiment, an area defined by the entire width of the original 2 and a distance from the leading end to the trailing end of 10 to 15 mm) is equal to or more than a predetermined density (the present embodiment). (75% or more of the maximum density), it is detected whether or not the image is a high density solid image (S24). At this time, if the density is lower than the predetermined density (N in S24), the probability that the sticking of the printing paper P to the plate cylinder 45 occurs is low.
In this case, a general plate making operation is started in which a perforation is started from a normal position to perform perforation in a normal area (S25). Then, general printing using the stencil sheet R made by such a general method is performed on a stencil printing mechanism unit 5 on a printing sheet P such as a standard plain paper such as A4 size.
Is performed (S26).

However, when the density is equal to or higher than the predetermined density (Y in S24), a margin is provided at a leading end of the stencil sheet R over a predetermined distance, so that the size of the stencil sheet R is slightly reduced as compared with the case of normal stencil making. A display indicating that plate making is to be performed, or a display indicating that the printing area (image) on the printing paper P will be slightly reduced by performing such reduction of the plate making as compared with a normal case is displayed. It is displayed on the screen of the unit 106 (S28). Then, the user selects whether or not to actually reduce the image size of the perforation (that is, to reduce the perforation area) (S29). At this time, for example, the original image may be slightly reduced like a general photograph or illustration, but rather, a margin is provided at the peripheral portion of the printing paper P by reducing the size, which is preferable in image layout. In the case of such an original, it is selected that the image to be made can be reduced (Y in S29), and such reduced printing is executed by the plate making section 3 (S3).
0). Then, the stencil printing mechanism section 5 executes printing using the stencil sheet R thus made (S31).

Alternatively, at this time, if the original image is an image that is required to be printed exactly at 1: 1 such as, for example, a precise design drawing, the user must reduce the image to be made. In such a case, it is not selected to reduce the image to make a plate (N in S29). In this case, for example, "If the original is made as it is, a paper discharge jam is likely to occur. Is displayed on the display unit 106 (S35), and the plate making unit 3 perforates the stencil sheet R with a normal size (1/1 magnification) image. General 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).

As described above, the density of the leading end of the original image, that is, the density of the portion corresponding to the leading end in the rotation direction when the stencil sheet R made on the basis of the original image is applied to the plate cylinder 45, is When the density is high enough to cause the phenomenon that the printing paper P sticks to the plate cylinder 45 at the time of printing, a predetermined area such as a distance of 10 to 15 mm from the leading end to the trailing end of the stencil sheet R is used. Stencil making is performed by reducing the image size perforated on the stencil sheet R so as to provide a margin. In the margin provided at the leading end of the stencil sheet R in this manner,
Since the printing paper P does not stick during printing, the leading end of the printing paper P after printing is easily separated from the plate cylinder 45. 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 useful characteristics of the stencil printing apparatus as a simple printing apparatus for performing high-quality printing with high efficiency.

Further, when the size of the image to be punched is reduced as described above, the user is notified in advance by displaying this on the display unit 106 and the user actually performs the punching based on the display. Whether or not to reduce the image size to be performed can be made selectable before the actual plate making starts. In this way, in performing plate making by reducing the image to be punched, by notifying the user in advance of that, it is determined whether or not such plate making may be performed.
In other words, the user can make a selection in an interactive manner.

In the second embodiment, the case where the user manually selects whether to reduce the original image and make a plate when the leading end of the original image has a high density has been described. The control unit 10 determines whether or not such reduced plate making is possible.
It may be performed automatically by 0 or the like. That is, for example, in the case of a stencil printing apparatus that adopts a stencil printing system that performs image representation by performing binary perforation on the stencil sheet R, the entire image data obtained by reading from the original 2 Calculates the ratio of the number of dots corresponding to the actual perforation of the total number of dots assumed in the above, and based on the ratio, the original image is an image that may be reduced, such as a photograph, a picture, or a color illustration. It may be automatically determined whether there is an image or whether the image is likely to cause inconvenience when reduced, such as a design drawing or a blank map. For example, if the number of dots pertaining to actual perforation is less than 50%, the image is determined to be an image such as a design drawing or a blank map, and if it is 50% or more, it is an image such as a photograph, a picture, or a color illustration. It is also possible to use a method of determining.

Note that, based on the ratio of the number of dots pertaining to the actual perforation to the total number of dots assumed in the entire area of one image as described above, the image in the predetermined area at the leading end of the original image is determined. It is also possible to detect whether the density is equal to or higher than a predetermined density. For example, the original image is reproduced with respect to the total number of dots assumed in a predetermined area at the leading end of the original in the image read from the original 2 (that is, the total number of dots if the entire predetermined area is perforated). In order to do so, the ratio of the number of dots that are actually punched in the predetermined region at the tip (that is, the number of dots pertaining to actual punching) is calculated, and the ratio is set as the predetermined density in the above-described embodiment, for example. If it is 75% or more, it may be determined that the density is "predetermined density or more", or if it is less than 75%, it may be determined that it is "less than the predetermined density".

In the first and second embodiments,
In any case, when the document 2 is set on the document setting table 21, which one of the four peripheral portions of the document image corresponds to the leading end of the stencil sheet R in the rotation direction of the plate cylinder 45 has already been determined. However, in the original reading stage, it may be undecided which one of the sides finally corresponds to the leading end of the plate cylinder 45 in the rotation direction. This is because, for example, when printing on A4 size printing paper P, the shorter width direction is the rotation direction of the plate cylinder 45 than the case where the longitudinal direction matches the rotation direction of the plate cylinder 45. The method adopted from the viewpoint that the stencil sheet R is desirably formed so as to match the above is preferable in that the length of the stencil sheet R used for one image can be shortened and the stencil sheet R can be saved. However, in such a case, after reading an image from the document 2 set on the document setting table 21, the direction of the image may be transposed so that the image is reversed so as to make a plate. For this reason, if there is a solid area on any one side of the four peripheral portions of the original image, if the image is transposed during plate making, one side of the solid may come to the leading end in the plate cylinder rotation direction. Therefore, there is a possibility that the printing paper P sticks to the plate cylinder 45 due to this. In order to cope with such a case, if there is a solid area on any one side of the four peripheral portions of the document image,
A margin may be provided at the leading end of the stencil sheet R in the plate cylinder rotation direction.

In the first and second embodiments,
In each case, a case is described in which a document image is once completely read by the document reading unit 1, and then image data of the leading edge and the trailing edge is extracted from the read image data and the image density of those portions is detected. However, when the read original images are sequentially transmitted to the plate making section 3 to make a plate, the image sensor 31 for reading the original is used.
Separately, using a dedicated optical sensor or the like for detecting the image density of a predetermined region at the leading end or the trailing end of the original image,
The image density of the predetermined area may be detected.

In the first and second embodiments, when stencil making is performed so that a predetermined margin is provided at the leading end of the stencil sheet R, the occurrence of paper discharge jams and the like is thereby effectively prevented. It is needless to say that the user can be informed of the fact that it can be prevented by displaying it on a display unit or the like.

Further, the technology according to the first embodiment and the technology according to the second embodiment may be used together. That is, when the image density of the leading end of the document 2 is high, the start position of the perforation on the stencil sheet R is set to the first position.
However, by shifting the leading end in this manner, the image at the rear end of the image is cut over the predetermined distance. Become. However, when it is not desirable to cut the image at the trailing end, the method of reducing the entire image to be made as shown in the second embodiment is adopted, and the leading end of the stencil sheet R is adopted. It is also possible to provide a margin portion and eliminate the need to cut the image at the rear end. Note that, in many cases, a high-density document image at both the leading edge and the trailing edge is a photograph or a picture. However, in the case of such a document, the original image is shifted from the plate making method according to the first embodiment. As described in the above-described embodiment, it is more preferable to use the method of reducing the image according to the second embodiment to make a plate. On the other hand, in the case of a document such as a design drawing which may cause inconvenience when reduced, a margin is provided by shifting the document over a predetermined distance as shown in the first embodiment, and the image to be made Is preferably set to 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 and specification of the document. By doing so, it becomes possible to use different plate making methods appropriately corresponding to the type and specifications of the original.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration mainly of a mechanical 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 according to the present invention.

FIG. 3 is a flowchart illustrating 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 a main part of an operation when plate making is started from a rear end side.

FIG. 5 is a flowchart illustrating an outline of the operation of the stencil printing apparatus according to the second embodiment;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 original reading section 3 stencil making section 5 stencil printing mechanism section 7 plate discharging section 9 paper feeding section 11 paper discharging section 100 control section 101 image processing section 102 density detecting section

Claims (9)

[Claims] 1. A stencil printing method for making a stencil sheet by perforating an unperforated stencil sheet based on an image of an original, wherein at least one of four peripheral parts of the original is provided. Wherein, when the image density of the predetermined area is equal to or higher than the predetermined density, the stencil printing is performed by providing a blank portion over a predetermined distance from the leading end of the stencil sheet. 2. A stencil printing method for making a stencil sheet by perforating an unperforated stencil sheet based on an image of a document, wherein the leading edge of the document corresponding to the leading end of the stencil sheet is provided. A stencil printing method for stencil printing, wherein when the image density of a predetermined area of the stencil sheet is equal to or higher than a predetermined density, the stencil printing is performed by providing a blank space over a predetermined distance from the leading end of the stencil sheet. 3. When the image density of a predetermined area at the leading end of the original corresponding to the leading end of the stencil sheet is equal to or higher than a predetermined density, perforation is performed based on the image of the original having the image density lower than the predetermined density. 2. The margin portion is provided by punching an image corresponding to the image of the document at a magnification lower than the magnification of the image when performing the operation.
Or a stencil printing method in stencil printing according to 2. 4. A perforating means for perforating an unperforated stencil sheet based on an image of an original to make the stencil sheet, and printing the stencil sheet on a printing sheet by winding the stencil sheet around a plate cylinder. A stencil printing apparatus comprising: a stencil printing device comprising: a stencil printing device comprising: a stencil printing device comprising: a stencil printing device; A stencil printing apparatus, wherein, when it is detected that the density is equal to or higher than the predetermined density, the stencil printing machine performs the stencil making by providing a blank space over a predetermined distance from the leading end of the stencil sheet. 5. A perforating means for perforating an unperforated stencil sheet based on an image of an original to make a stencil sheet, and printing the stencil sheet on a printing drum by winding the stencil sheet around a printing drum. A stencil printing apparatus comprising: a stencil printing device comprising: a stencil printing device comprising: a stencil printing device having a stencil printing device; A stencil printing apparatus, wherein, when it is detected that the density is equal to or higher than the predetermined density, the stencil printing machine performs the stencil making by providing a blank portion over a predetermined distance from the leading end of the stencil sheet. 6. A method according to claim 1, wherein said plate making means perforates an image corresponding to the image of said document at a lower magnification than a magnification of said image when perforating based on an image of said document having said image density lower than a predetermined density. The stencil printing apparatus according to claim 4, wherein the margin is provided by the following. 7. A perforating means for perforating an unperforated stencil sheet based on an image of an original to make a stencil sheet, and printing the stencil sheet on a printing cylinder by winding the stencil sheet around a plate cylinder. A stencil printing apparatus having a stencil printing device, wherein the image density of a predetermined region at one end of both ends of the document corresponding to the leading end and the trailing end of the stencil sheet is equal to or higher than a predetermined density, and Detecting means for detecting that the image density of the predetermined area at the end of the predetermined area is lower than the predetermined density, wherein the plate making means detects that the image density of the predetermined area at the other end is lower than the predetermined density. The stencil printing machine performs the stencil making so that the end of the stencil sheet having a density lower than the predetermined density corresponds to the leading end of the stencil sheet. 8. A notifying means for notifying at least one of visual information and audio information that the margin portion is provided or that a margin portion is provided in an image printed on printing paper. The stencil printing apparatus according to claim 4, 5 or 7, further comprising: 9. When the margin is provided, the margin and the image density corresponding to the image of the document are lower than the image magnification when performing perforation based on the image of the document having a density lower than a predetermined density. A notification unit configured to notify at least one of visual information and audio information of at least one of the effect of punching the image and the effect of reducing the image printed on the printing paper. The stencil printing apparatus according to claim 6, wherein: