JP2010284914A - Double-side stencil printing equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a printing medium from being stained due to retransferring without thinly printing the back side of printing paper as well when a spread manuscript is read. <P>SOLUTION: Double-side stencil printing equipment includes: a first printing part 4 for printing one side of the printing paper W; a second printing part 5 for printing the other side of the printing paper W having been turned by a reversing part 10; an image reading part 2 for reading in images from the spread manuscript 101; an image dividing and layout part 20a for laying out the nearly half images of the spread manuscript 101 previously read as a first image and the nearly half images of the spread manuscript 101 lately read as a second image; a density correcting part 20b for correcting the density of the first image to be lower than that of the second image; and a plate making part 6, 7 for producing a first stencil paper G1 based on the first image with the corrected density, and also for producing a second stencil paper G2 based on the second image, which has been laid out by the image dividing and layout part 20a. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a double-sided stencil printing apparatus capable of double-sided printing, and more particularly to a double-sided stencil printing apparatus capable of preventing printing paper from being soiled and obtaining good printing paper even when a two-page spread document is printed on both sides of the printing paper.

In general, a stencil printing apparatus that performs printing by winding a stencil sheet that has been stenciled around a drum, feeding paper to the drum, and pressing the supplied printing paper against the drum by a press roller is good. Are known.

  In recent years, double-sided printing for printing on the front and back surfaces of paper has been promoted from the viewpoint of effective use of resources.

  Therefore, Patent Document 1 proposes a double-sided stencil printing apparatus capable of double-sided printing of printing paper. Specifically, the first stencil sheet made based on the read first image is wound around the first drum, and the second stencil sheet made based on the read second image. Is wrapped around the second drum. Then, the printing paper is fed to the first drum, and the printing paper is pressed against the first drum by the first press roller to print the first image on the surface of the printing paper. Furthermore, after the printed paper is turned upside down, it is transported to the second drum, and the printing paper is pressed against the second drum by the second press roller, whereby the second image is printed on the printing paper. A double-sided stencil printing apparatus for printing on the back side has been proposed.

  However, in the double-sided stencil printing apparatus described in Patent Document 1, since the printing paper is pressed against the second drum by the second press roller, the first image printed on the surface of the printing paper is the second press roller. When the first image transferred to the second press roller is transferred to the printing paper (hereinafter referred to as retransfer), the surface of the printing paper may become dirty.

  Therefore, Patent Document 2 discloses that the energy applied to the thermal head at the time of making the first stencil sheet is lower than the energy applied to the thermal head at the time of making the second stencil sheet. 2. Description of the Related Art There has been proposed a double-sided printing apparatus that performs printing by making the printing density on the front side of the printing paper lower than the printing density on the back side by making the perforation diameter of the base paper smaller than the perforation diameter of the second stencil base paper.

JP 2005-29375 A Japanese Patent Laid-Open No. 2005-144897

  On the other hand, a printing apparatus having a book mode printing function for reading a spread original document bound at the center of a booklet or the like and performing double-sided printing based on the read spread original is well known. Specifically, the front side of the printing paper is printed based on the left half image of the read spread original, and the back side of the printing paper is printed based on the right half image of the read double original.

  In a printing apparatus having such a general book mode printing function, when reading a double-page spread document, the left half image and the right half image are read under the same conditions. It was printed.

  Therefore, in the double-sided printing apparatus described in Patent Document 2 to which the book mode printing function is applied, when a double-sided original is read and double-sided printing of the printing paper is performed, the front and back surfaces of the printing paper are printed with the same density. From the viewpoint of preventing re-transfer, there is a case in which printing is performed thinly to the back side of the printing paper that does not need to be printed thinly.

  The present invention has been made in view of the above problems, and provides a double-sided stencil printing apparatus that prevents smearing of a printing medium due to retransfer without thinly printing to the back surface of a printing paper even when reading a spread original. The purpose is to do.

  In order to achieve the above object, a first feature of the double-sided stencil printing apparatus according to the present invention is that a first printing unit that prints one side of a printing medium, and one side is printed by the first printing unit. A reversing unit for reversing the printed medium, a second printing unit for printing the other surface of the printing medium reversed by the reversing unit, an image reading unit for reading an image from a spread original, and the image reading unit. Image division allocating means for allocating substantially half of the spread document read first as the first image and half of the spread document read as the second image; and the density of the first image A density correction unit that corrects the density of the first image so as to be lower than the density of the second image, and the first printing hand based on the first image whose density is corrected by the density correction unit. Generates a first stencil sheet for printing, and generates a second stencil sheet for printing by the second printing unit based on the second image allocated by the image dividing / allocating unit. And a plate making means.

  In order to achieve the above object, a second feature of the double-sided stencil printing apparatus according to the present invention is that the plate making means is configured such that the perforation diameter of the first stencil sheet is smaller than the perforation diameter of the second stencil sheet. A heat-reducing plate making process for producing the first stencil sheet by hot perforation with a small applied energy, a first press in which the first printing unit is in pressure contact with a first drum provided in the first printing unit A reduced-pressure printing process for printing so that the pressure of the roller is smaller than the pressure of the second press roller that is in pressure contact with the second drum included in the second printing unit, and the image thinning unit are configured by the density correction unit. The thinning plate making process performs thinning of the image on the first image whose density has been corrected, and the plate making unit generates the first stencil sheet based on the thinned first image. At least It is to perform a Zureka one process.

  In order to achieve the above object, a third feature of the double-sided stencil printing apparatus according to the present invention is that the image division allocating unit determines a size of a spread document read by the image reading unit, and the determined spread is determined. Based on the size of the original, the half of the image that is read first is assigned as the first image, and the half of the spread original that is read later is assigned as the second image.

  According to the double-sided stencil printing apparatus according to the present invention, even when a spread original is read, the printing medium can be prevented from being soiled by retransfer without thinly printing the back side of the printing paper.

It is the block diagram which showed the structure of the double-sided stencil printing apparatus which concerns on Example 1 of this invention. It is a functional block diagram which showed the functional structure of the double-sided stencil printing apparatus which concerns on Example 1 of this invention. It is the flowchart which showed the processing flow of the double-sided stencil printing apparatus which concerns on Example 1 of this invention. It is the figure explaining the image allocation by the image division | segmentation allocation part of the control part with which the double-sided stencil printing apparatus which concerns on Example 1 of this invention is provided. It is a figure explaining the density correction by the density correction part of the control part with which the double-sided stencil printing apparatus which concerns on Example 1 of this invention is provided. It is a functional block diagram which showed the function structure of the double-sided stencil printing apparatus which concerns on Example 2 of this invention. It is the flowchart which showed the processing flow of the double-sided stencil printing apparatus which concerns on Example 2 of this invention. It is a figure explaining the thinning-out process by the image thinning-out part of the control part of the double-sided stencil printing apparatus which concerns on Example 2 of this invention. It is the flowchart which showed the processing flow of the double-sided stencil printing apparatus which concerns on Example 3 of this invention. It is a perspective view of the peripheral part of the 1st printing part of the double-sided stencil printing apparatus which concerns on Example 4 of this invention. It is a side view of the peripheral part of the 1st printing part of the double-sided stencil printing apparatus which concerns on Example 4 of this invention. It is a functional block diagram which showed the function structure of the double-sided stencil printing apparatus which concerns on Example 4 of this invention. It is the flowchart which showed the processing flow of the double-sided stencil printing apparatus which concerns on Example 4 of this invention.

  A mode for carrying out the present invention will be described below.

  In Embodiment 1 of the present invention, a double-sided stencil printing apparatus that prints the surface of a printing paper (printing medium) with an upstream drum and prints the back surface of the printing paper with a downstream drum, the spread original is printed on the printing paper. In the case of printing on both sides, a double-sided stencil printing apparatus that corrects the image density so that the density of the front surface of the printing paper is lower than the density of the back surface will be described as an example.

<Configuration of double-sided stencil printing machine>
A configuration of the double-sided stencil printing apparatus according to Embodiment 1 of the present invention will be described.

  FIG. 1 is a configuration diagram illustrating a configuration of a double-sided stencil printing apparatus according to Embodiment 1 of the present invention.

  As shown in FIG. 1, the double-sided stencil printing apparatus 1 includes an image reading unit 2, a paper feeding unit 3, a first printing unit 4, a second printing unit 5, a first plate making unit 6, A second plate making unit 7, a first plate discharging unit 8, a second plate discharging unit 9, a reversing unit 10, and a paper discharge unit 11 are provided.

  The image reading unit 2 includes a cover unit 21 and a main body unit 22.

  The cover part 21 is supported on the main body part 22 by a hinge mechanism or the like so as to be opened and closed, and has a structure that can be opened and closed by a user. A platen glass 25 serving as a document table is provided on the upper surface of the main body 22. A spread original 101 to be read is a booklet bound at the center, and is placed on the platen glass 25 by a user's manual work.

  The main body 22 includes a full-rate carriage 26, a half-rate carriage 27, an imaging lens 28 disposed on the optical axis of light from the half-rate carriage 27, and an optical axis of light collected by the imaging lens 28. And a photoelectric conversion element 29 disposed above.

  The full rate carriage 26 and the half rate carriage 27 are provided so as to be movable in the sub-scanning direction (left-right direction in the figure) using a common carriage moving motor (not shown) as a drive source. When moving in the sub-scanning direction, the half-rate carriage 27 moves with a movement amount (moving speed) that is ½ that of the full-rate carriage 26, so that the carriages 26 and 27 are moved to any position in the sub-scanning direction. However, the optical distance from the document surface on the platen glass 25 to the light receiving portion of the photoelectric conversion element 29 is always maintained constant.

  The full rate carriage 26 has a lamp (light source) 26a and a first mirror 26b, and the half rate carriage 27 has a second mirror 27a and a third mirror 27b.

  The lamp 26 a emits light toward the surface to be read of the spread original 101. The first mirror 26b, the second mirror 27a, and the third mirror 27b sequentially reflect the reflected light from the facing document surface when the lamp 26a emits light toward the facing document 101.

  The imaging lens 28 images the light reflected by the third mirror 27b on the light receiving surface of the photoelectric conversion element 29 at a predetermined reduction magnification. The photoelectric conversion element 29 is an image sensor for reading the double-page spread original 101, and is constituted by a solid-state imaging element (CCD or the like). The photoelectric conversion element 9 reads the luminance of the reflected light from the double-page spread original 101, performs photoelectric conversion on a pixel basis, and outputs an analog luminance signal.

  The first stencil making unit 6 includes a first stencil storage unit 61 that stores the rolled first stencil stencil sheet G1 and a first stencil storage unit 61 that is disposed downstream of the first stencil storage unit 61. Thermal head 62, a first platen roll 63 disposed at a position opposed to the first thermal head 62, and a pair disposed downstream of conveyance of the first platen roll 63 and the first thermal head 62. The first base paper feed roll 64 and a first base paper cutter 65 disposed downstream of the pair of first base paper feed rolls 64.

  Then, the first plate making unit 6 conveys the long first stencil sheet G1 by the rotation of the first platen roll 63 and the first base paper feed roll 64, and the image read by the image reading unit 2 Based on the data, each point-like heating element of the first thermal head 62 selectively generates heat to perform heat-sensitive perforation in the first stencil sheet G1, and make the first stencil sheet G1 thus made. The first stencil sheet G1 having a predetermined length is cut by the first stencil cutter 65.

  The second plate making unit 7 has the same configuration as that of the first plate making unit 6, and a second base paper storage unit 71 for storing the rolled long second stencil paper G 2, and this A second thermal head 72 disposed downstream of the second base paper container 71, a second platen roll 73 disposed at a position opposite to the second thermal head 72, and the second platen roll 73 and a pair of second base paper feed rolls 74 disposed downstream of the second thermal head 72 and a second base paper cutter 75 disposed downstream of the pair of second base paper feed rolls 74. Have.

  Then, the second plate making unit 7 produces the second stencil sheet G2 in the same manner as the first plate making unit 6.

  The first stencil printing unit 8 was peeled off the first stencil sheet G1 which was released from the outer periphery of the first drum 41 of the first printing unit 4 described later from the first drum 41. The first stencil sheet G1 is stored in a stencil box (not shown).

  Similarly to the first plate discharging unit 8, the second plate discharging unit 9 removes the second stencil sheet G2 unclamped from the outer peripheral surface of the second drum 51 of the second printing unit 5 described later. The second stencil sheet G2 peeled off from the drum 51 is accommodated in a stencil box (not shown).

  The paper feed unit 3 includes a paper feed tray 31 on which the print paper W is stacked, a primary paper feed roll 32 that transports only the uppermost print paper W from the paper feed base 31, and the primary paper feed roll 32. A pair of secondary paper feeds transporting the printing paper W conveyed by the first drum 41 and the first press roller 43 in synchronization with the rotation of the first drum 41 of the first printing unit 4 to be described later. And a roll 33.

  The first printing unit 4 is provided on a first drum 41 that rotates in the direction of arrow A in FIG. 1 by a driving force of a main motor (not shown), and an outer peripheral surface of the first drum 41. A base paper clamp unit 42 that clamps the leading end of the stencil base paper G1 and a transport belt 44 that transports the printing paper W to the reversing unit 10 are provided.

  Further, the first printing unit 4 has a first press roller 43 disposed below the first drum 41, and the first press roller 43 presses against the outer peripheral surface of the first drum 41. It is configured to be able to change between a pressing position to be moved and a standby position separated from the outer peripheral surface of the first drum 41. The first press roller 43 is always positioned at the pressing position during the printing mode period (including trial printing), and is positioned at the standby position during the period other than the printing mode.

  Then, the leading end of the first stencil sheet G1 conveyed from the first stencil making unit 6 is clamped by the stencil sheet clamping unit 42, and in this clamped state, the first drum 41 is rotated so that the first stencil sheet G1 is The first drum 41 is wound around the outer peripheral surface. Then, the printing paper W fed from the paper feeding unit 3 in synchronization with the rotation of the first drum 41 is applied to the first stencil sheet G1 wound around the first drum 41 by the first press roller 43. By pressing, the ink is pushed out from the perforation of the first stencil sheet G1, and the image is printed on the surface of the printing apparatus W.

  The printing paper W, on which the image is printed on the surface when the first press roller 43 is pressed against the first drum 41, is applied to the reversing unit 10 by the annular conveying belt 44 having both ends wound around a pair of rotating shafts. Be transported.

  The reversing unit 10 is disposed downstream of the first printing unit 4 in the transport direction of the printing paper W, and an annular reversing belt 101 formed in a porous structure is disposed in a semicircular shape. The reverse belt 101 is wound around a semicircular auxiliary member 102 and a pair of rollers 103 and 104, and at least one of the pair of rollers 103 and 104 is rotationally driven by a drive motor (not shown). Further, a suction unit 105 is provided inside the reversing belt 101 and sucks the printing paper W toward the reversing belt 101. The other surface of the printing paper W conveyed above the reversing belt 101 is sucked and the reversing belt 101 is rotated downward so that the printed surface of the printing paper W is not printed. The reverse side is reversed, and the printing paper W is conveyed to the stacking base 106 with the printing paper W reversed.

  On the stacking table 106, the printing paper W whose front surface and reverse surface are reversed is stacked.

  Further, the stacking table 106 can stack a plurality of printing sheets W. The printing sheet W printed on the front surface by the first printing unit 4 is stacked on the loading table 106 and temporarily stays there. This ensures the ink drying time. When a predetermined number of print sheets W are stacked on the stacking table 106, the stacked print sheets W are transported by an annular intermediate transport belt 107 having both ends wound around a pair of rotating shafts.

  The intermediate conveyance belt 107 is formed in a porous structure, and conveys the printing paper W by sucking one sheet at a time from the lowest side of the stacking table 106 by the suction means 108 provided inside. The transported printing paper W is transported to the second printing unit 5 by a pair of rollers 109 disposed on the downstream side in the transporting direction of the printing paper W with respect to the intermediate transport belt 107.

  Similar to the first printing unit 4, the second printing unit 5 is provided on the second drum 51 rotating in the direction of arrow A in FIG. 1 and the outer peripheral surface of the second drum 51. A stencil sheet G2 has a stencil sheet clamping portion 52 that clamps the leading end of the stencil sheet G2, and a second press roller 53 disposed below the second drum 51. Further, the second printing unit 5 transports the printing paper W reversed by the reversing unit 10 between the second drum 51 and the second press roller 53 in synchronization with the rotation of the second drum 51. A secondary paper feed roll 54 is provided.

  Similarly to the first printing unit 4, the second printing unit 5 outputs the second printing paper W fed from the pair of secondary paper feeding rolls 54 in synchronization with the rotation of the second drum 51. By pressing the second stencil sheet G2 wound around the second drum 51 by the press roller 53, ink is pushed out from the perforations of the second stencil sheet G2 and an image is printed on the back surface of the printing paper W. It has come to be.

  The paper discharge unit 11 includes a paper discharge belt 111 on which the printed print paper W is conveyed, and a paper discharge tray 112 on which the print paper W discharged from the paper discharge belt 111 is placed.

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

  As shown in FIG. 2, the double-sided stencil printing apparatus 1 according to the first embodiment of the present invention includes an image reading unit 2, a paper feeding unit 3, a first printing unit 4, a second printing unit 5, First plate making unit 6, second plate making unit 7, first plate discharging unit 8, second plate discharging unit 9, reversing unit 10, paper discharge unit 11, RAM 12, ROM 13, and operation Unit 15, control unit 20, and A / D conversion unit 23.

  Among these configurations, the image reading unit 2, the paper feeding unit 3, the first printing unit 4, the second printing unit 5, the first plate making unit 6, the second plate making unit 7, Since the first plate discharging unit 8, the second plate discharging unit 9, the reversing unit 10, and the paper discharge unit 11 have been described above, description thereof will be omitted.

  The RAM 12 is composed of a volatile semiconductor or the like, and stores data and the like necessary for the control unit 20 to execute various processes.

  The ROM 13 is composed of a nonvolatile semiconductor or the like, and stores data necessary for execution by the control unit 20 such as gamma values γ1 and γ2 described later, various control programs, and the like.

  The operation unit 15 includes operation keys, a display / input panel, and the like, and various operations such as start of plate making and start of printing are performed by the user pressing the operation key or touching the display / input panel. An operation signal that requires processing is generated, and the generated operation signal is supplied to the control unit 20. For example, the operation unit 15 generates an operation signal for requesting selection of a double-sided book mode for printing a double-page spread document on both sides of a print sheet based on a user operation, and the generated operation signal is transmitted to the control unit. 20 is supplied.

  The A / D conversion unit 23 converts the analog luminance signal supplied from the photoelectric conversion element 29 of the image reading unit 2 into a digital value, and supplies the converted digital luminance signal to the control unit 20.

  The control unit 20 performs central control of the double-sided stencil printing apparatus 1.

  In addition, the control unit 20 includes an image division allocation unit 20a, a density correction unit 20b, a binarization processing unit 20c, and a plate making control unit 20e.

  The image dividing / allocating unit 20a assigns an image that is approximately half of the spread document read first by the image reading unit 2 as a first image and an image that is approximately half of the spread document that is read later as a second image.

  The density correction unit 20b corrects the density of the first image so that the density of the first image is lower than the density of the second image.

  The binarization processing unit 20c performs binarization processing on the first image and the second image whose density has been corrected by the density correction unit 20b.

  The plate making control unit 20 e controls the first plate making unit 6 and the second plate making unit 7. Specifically, the plate making control unit 20e is based on the first image subjected to binarization processing by the binarization processing unit 20c after the density is corrected by the density correction unit 20b in the first plate making unit 6. The first printing unit 4 generates a first stencil sheet G1 for printing.

  In addition, the plate making control unit 20e causes the second printing unit 5 to print the second plate making unit 7 on the basis of the second image binarized by the binarization processing unit 20c. A stencil sheet G2 is generated.

<Operation of the double-sided stencil printing apparatus 1>
Next, the operation of the double-sided stencil printing apparatus 1 according to Example 1 of the present invention will be described.

  FIG. 3 is a flowchart showing a processing flow of the double-sided stencil printing apparatus 1 according to the first embodiment of the present invention.

  As shown in FIG. 3, the control unit 20 determines whether or not the double-sided book mode has been selected (step S101). Specifically, the control unit 20 determines whether or not an operation signal for setting the double-sided book mode is supplied from the operation unit 15 by a user operation.

  Next, when it is determined in step S101 that the double-sided book mode is selected (in the case of YES), the control unit 20 determines whether or not the start of plate making is requested (step S102). Specifically, the control unit 20 determines whether or not an operation signal for requesting the start of plate making is supplied from the operation unit 15 by a user operation.

  In step S102, when it is determined that the start of plate making is requested (in the case of YES), the image division allocation unit 20a of the control unit 20 is placed on the platen glass 25 based on the signal supplied from the image reading unit 2. The size of the spread spread document 101 is determined (step S105). Specifically, when a signal indicating detection / non-detection by a plurality of optical sensors provided in the image reading unit 2 is supplied from the image reading unit 2, the image division allocating unit 20a, based on this signal, For example, the size of the spread original 101 is determined as A4, B5, or the like.

  Next, the image division allocation unit 20a determines a specific position (step S107). Specifically, the image division assignment unit 20a determines the length L of the spread original 101 in the sub-scanning direction based on the size of the spread original 101 determined in step S105, and the length L in the sub-scanning direction. Let P be approximately half the length of. Then, the image division assigning unit 20a determines a position that is separated by P in the sub-scanning direction from the leading end position (reference position S) at which the spread original 101 is read.

  Next, the control unit 20 causes the image reading unit 2 to start reading the spread original 101 placed on the platen glass 25 (step S109). Specifically, while moving the full rate carriage 26 and the half rate carriage 27 in the sub-scanning direction, the lamp 26a emits light toward the surface to be read of the spread original 101, and the first mirror 26b and the second mirror 27a. The reflected light reflected by the third mirror 27 b is photoelectrically converted by the photoelectric conversion element 29, and a luminance signal for each line in the main scanning direction is supplied to the A / D converter 23.

  Then, the image division assigning unit 20a of the control unit 20 assigns the image for one line in the main scanning direction, that is, the luminance signal for one line in the main scanning direction supplied from the image reading unit 2 as the first image (step) S111).

  FIG. 4 is a diagram for explaining image assignment by the image division assignment unit 20a of the control unit 20 included in the double-sided stencil printing apparatus 1 according to the first embodiment of the present invention.

  As shown in FIG. 4, the image dividing / allocating unit 20a moves the full rate carriage 26 and the half rate carriage 27 to move the reference position S, which is the leading end position for reading the spread original 101, for each line in the main scanning direction. The read image is assigned as the first image 102.

  Next, the density correction unit 20b of the control unit 20 corrects the density of the first image 102 allocated for each line in the main scanning direction by the image division allocation unit 20a for each main scanning line (step S113). . Specifically, the density correction unit 20b is based on the luminance signal for one line in the main scanning direction supplied from the image reading unit 2, and when the luminance value before density correction is x, the following (Formula 1) Is used to calculate the luminance value y after density correction.

y = x ^{(1 / γ2)} (Formula 1)
FIG. 5 is a diagram illustrating density correction by the density correction unit 20b of the control unit 20 provided in the double-sided stencil printing apparatus 1 according to the first embodiment of the present invention.

  A gamma correction curve 201 shown in FIG. 5 is a curve showing a gamma characteristic when performing density correction of the second image 103 to be described later, and a gamma correction curve 202 is expressed by (Equation 1), 6 is a curve showing a gamma characteristic when density correction of an image 102 is performed.

  Thus, since the gamma correction curve 201 is used for density correction of the second image 103 and the gamma correction curve 202 is used for density correction of the first image 102, the density correction unit 20 b The density correction can be performed so that the density of the first image 102 is lower than the density of the second image 103.

  The density correction unit 20b uses (Equation 1), that is, the gamma correction curve 202 so that the density of the first image 102 is lower than the density of the second image 103 (to be described later). Density correction of one image 102 is performed.

  Next, the binarization processing unit 20c of the control unit 20 performs binarization processing for each line in the main scanning direction on the first image whose density is corrected in step S113 (step S115). As a result, the first image is represented by “1” or “0”.

  Then, the plate making control unit 20e causes the first plate making unit 6 to perform the first stencil for each line in the main scanning direction based on the first image for one main scanning line binarized in step S115. The base paper G1 is made (step S116). Specifically, based on the instruction from the plate making control unit 20e, the first plate making unit 6 causes the first platen roll 63 and the first base paper feed roll 64 to rotate to rotate the first long stencil sheet G1. , And the point-like heating elements of the first thermal head 62 selectively generate heat based on the first image for one main scanning line binarized in step S115. Thermal piercing is performed on the stencil sheet G1.

  Next, the control unit 20 moves the reading position by the full rate carriage 26 of the image reading unit 2 by one line in the sub-scanning direction (step S117).

  Then, the image division assignment unit 20a of the control unit 20 determines whether or not the reading position by the image reading unit 2 has reached the specific position R determined in step S107 (step S119).

  When it is determined in step S119 that the reading position by the image reading unit 2 has reached the specific position R (in the case of YES), the image dividing / allocating unit 20a of the control unit 20 displays an image for one line in the main scanning direction, that is, The luminance signal for one line in the main scanning direction supplied from the image reading unit 2 is assigned as the second image (step S121).

  As shown in FIG. 4, the image division allocating unit 20 a moves the full rate carriage 26 and the half rate carriage 27 to move the image reading unit from the reference position S, which is the leading edge position for reading the spread original 101, to the specific position R. 2 is assigned as the first image 102, and the image read from the specific position R for each line in the main scanning direction is assigned as the second image 103.

  Next, the density correction unit 20b of the control unit 20 performs density correction for each main scanning line on the second image 103 allocated by the image division allocation unit 20a for each line in the main scanning direction (step S123). . Specifically, the density correction unit 20b is based on the luminance signal for one line in the main scanning direction supplied from the image reading unit 2, and when the luminance value before density correction is x, the following (Formula 2) Is used to calculate the luminance value y after density correction.

y = x ^{(1 / γ1)} (Formula 2)
Next, the binarization processing unit 20c of the control unit 20 performs binarization processing for each line in the main scanning direction on the second image whose density has been corrected in step S123 (step S124). As a result, the second image is represented by “1” or “0”.

  Then, the plate making control unit 20e causes the second plate making unit 7 to generate the second stencil for each line in the main scanning direction based on the second image for one main scanning line binarized in step S124. The base paper G2 is made (step S125). Specifically, based on an instruction from the plate making control unit 20e, the second plate making unit 7 rotates the second platen roll 73 and the second base paper feed roll 74 to form a long second stencil sheet G2. The point-like heating elements of the second thermal head 72 selectively generate heat based on the second image for one main scanning line binarized in step S124. Thermal piercing is performed on the stencil sheet G2.

  Next, the control unit 20 moves the reading position by the full rate carriage 26 of the image reading unit 2 by one line in the sub-scanning direction (step S127).

  Then, the image division assignment unit 20a of the control unit 20 determines whether or not the reading position by the image reading unit 2 has reached the end position R (step S129). Here, the end position Q is a position separated from the reference position S by the length L of the spread original in the sub-scanning direction.

  As described above, according to the double-sided stencil printing apparatus 1 according to the first embodiment of the present invention, the first image is obtained by setting the first half of the spread original 101 read by the image reading unit 2 as the first image. After correcting the density of the first image for each main scanning line so that the density of the first image is lower than the density of the second image, the first stencil sheet G1 is made for each main scanning line, and this plate making is performed. In addition, printing is performed on the surface of the printing paper W using the first stencil sheet G1, and approximately half of the spread original 101 to be read later is assigned as the second image, and the density of the first image is the second image. The density of the second image is corrected for each main scanning line so as to be lower than the density of the second stencil sheet G2, and then the second stencil sheet G2 is made for each main scanning line. Is used to print on the back side of the printing paper W. Even when reading a document 101, without printing thinned to the back surface of the printing paper W, contamination of printed sheets W by re-transfer can be prevented.

  Further, according to the double-sided stencil printing apparatus 1 according to the first embodiment of the present invention, the density correction, the binarization process, and the stencil sheet making are sequentially performed for each main scanning line, so that the image is temporarily stored. Therefore, a large amount of memory is not required and printing can be performed quickly.

  In the first embodiment of the present invention, the first plate making section 6 for producing the first stencil sheet G1 to be wound around and attached to the outer peripheral surface of the first drum 41, and the outer peripheral surface of the second drum 51. The second stencil sheet G2 for producing the second stencil sheet G2 to be wound around is provided with the second stencil printing section 7, but not limited to this. It is good also as a structure provided with one platemaking part which produces 1st stencil paper G1 and 2nd stencil paper G2 wound around the outer peripheral surface of the 2nd drum 51, and is attached.

  Specifically, the plate making unit is supported movably on rails provided above the first printing unit 4 and the second printing unit 5, and the plate making unit is positioned above the first printing unit 4. In this case, a first stencil sheet G1 to be wound around and attached to the outer peripheral surface of the first drum 41 is produced, and the first stencil sheet G1 thus made is supplied to the first printing unit 4 and the plate making is performed. The second stencil sheet G2 to be wound around and attached to the outer peripheral surface of the second drum 51 when the part is located on the upper part of the second printing unit 5 is produced and the second stencil sheet G2 thus made is made. May be supplied to the second printing unit 5.

  In the first embodiment of the present invention, the image dividing / allocating unit 20a determines the position separated by P in the sub-scanning direction from the leading edge position (reference position S) for reading the spread original 101 as the specific position R. However, the present invention is not limited to this. Absent.

  For example, P is given a certain width such as P1 to P2, the position separated from the reference position S by P1 in the sub-scanning direction is set as the first specific position R1, and from the reference position S by P2 in the sub-scanning direction. The separated position is defined as a second specific position R2. The image division assigning unit 20a assigns the image from the reference position S to the first specific position R1 in the sub-scanning direction read by the image reading unit 2 as the first image, and from the second specific position R2. Images up to the end position Q may be assigned as the second image.

  In the first embodiment of the present invention, an image is read from a double-page spread document for each main scanning line, the read image for one main scanning line is sequentially corrected, and the corrected image for one main scanning line is used. The double-sided stencil printing apparatus 1 that sequentially generates stencil sheets has been described as an example, but the present invention is not limited to this.

  For example, an image may be sequentially read pixel by pixel from a spread original, and the read image for one pixel may be corrected sequentially, and stencil sheets may be sequentially generated based on the corrected image for one pixel. Good.

  Specifically, the double-sided stencil printing apparatus has an image reading unit 2 that sequentially reads an image from the spread original 101 pixel by pixel, and a half image of the spread original 101 that is read first by the image reading unit 2 as a first image. The image division assignment unit 20a that assigns approximately half of the spread original 101 that is read later as the second image, and the density of the first image assigned by the image division assignment unit 20a is greater than the density of the second image. The density correction unit 20b for sequentially correcting the density of the pixels read by the image reading unit 2 and assigned as the first image by the image division / assignment unit 20a and the density correction unit 20b sequentially correct the density so as to be lower. A first stencil making unit 6 for sequentially generating a first stencil sheet G1 for printing by the first printing unit 4 based on the obtained pixels, and an image reading unit 2 The second plate making unit 7 that sequentially generates the second stencil sheet G2 to be printed by the second printing unit 5 based on the pixels that are read in and assigned as the second image by the image division and assignment unit 20a. May be provided.

  As a result, the double-sided stencil printing apparatus can process in real time the processing from image reading to plate making.

  In Embodiment 1 of the present invention, when the spread original 101 is printed on both sides of the printing paper W, the double-sided stencil printing apparatus corrects the image density so that the density of the front surface of the printing paper W is lower than the density of the back surface. 1 was described as an example.

  In Embodiment 2 of the present invention, a double-sided stencil printing apparatus that performs thinning processing on an image whose density has been corrected and performs thinning plate making processing based on the thinned image is taken as an example. I will give you a description.

<Configuration of double-sided stencil printing machine>
A double-sided stencil printing apparatus 1A according to Example 2 of the present invention has the same configuration as the double-sided stencil printing apparatus 1 according to Example 1 of the present invention shown in FIG.

  Further, as shown in FIG. 6, the double-sided stencil printing apparatus 1 </ b> A according to the second embodiment of the present invention includes an image reading unit 2, a paper feeding unit 3, a first printing unit 4, and a second printing unit 5. The first plate making unit 6, the second plate making unit 7, the first plate discharging unit 8, the second plate discharging unit 9, the reversing unit 10, the paper discharge unit 11, the RAM 12, and the ROM 13. The operation unit 15 and the control unit 20A are provided.

  Among these configurations, the configuration other than the control unit 20A is the same as the configuration given the same reference numerals of the double-sided stencil printing apparatus 1 according to the first embodiment of the present invention shown in FIG. Omitted.

  The control unit 20A performs central control of the double-sided stencil printing apparatus 1.

  The control unit 20A includes an image division assignment unit 20a, a density correction unit 20b, a binarization processing unit 20c, an image thinning unit 20d, and a plate making control unit 20e in terms of its functions.

  Among these configurations, the configuration other than the image thinning-out unit 20d is the same as the configuration with the same reference numerals provided in the control unit 20 of the double-sided stencil printing apparatus 1 according to the first embodiment of the present invention illustrated in FIG. Therefore, explanation is omitted.

  The image thinning unit 20d generates a thinned image by performing a thinning process on the first image whose density has been corrected by the density correction unit 20b.

<Operation of the double-sided stencil printing apparatus 1A>
Next, the operation of the double-sided stencil printing apparatus 1A according to Example 2 of the present invention will be described.

  FIG. 7 is a flowchart showing a processing flow of the double-sided stencil printing apparatus 1A according to the second embodiment of the present invention. Here, in the flowchart shown in FIG. 7, the processing of steps S101 to S115 and steps S119 to S129 shows the processing flow of the double-sided stencil printing apparatus 1 according to the first embodiment of the present invention shown in FIG. Since the processing contents are the same as those of the processing of the same step number shown in the flowchart, description thereof will be omitted.

  As shown in FIG. 7, when the first image is binarized for each main scanning line by the binarization processing unit 20c in step S115, the image thinning unit 20d of the control unit 20A performs binarization. A thinning process is executed for each main scanning line on the processed first image (step S201). For example, the image thinning unit 20d performs a thinning process on a pixel-by-pixel basis for the binarized first image for one main scanning line.

  FIG. 8 is a diagram for explaining the thinning process by the image thinning unit 20d of the control unit 20A of the double-sided stencil printing apparatus 1 according to the second embodiment of the present invention. FIG. 8 shows an example of a first image that is thinned out by one pixel alternately in the main scanning direction and the sub-scanning direction when the binarized first image includes a solid portion. Yes.

  As shown in FIG. 8, in the first image before the thinning process, black pixels having a pixel value “1” are continuous.

  On the other hand, the first image after the thinning process is thinned one pixel at a time in the main scanning direction and the sub-scanning direction in the solid portion, so that the number of perforations is reduced and retransfer can be further prevented. .

  Next, as illustrated in FIG. 7, the plate making control unit 20 e causes the first plate making unit 6 to perform the first stencil sheet for each main scanning line based on the first image thinned out in step S <b> 201. G1 is made (step S202). Specifically, based on the instruction from the plate making control unit 20e, the first plate making unit 6 causes the first platen roll 63 and the first base paper feed roll 64 to rotate to rotate the first long stencil sheet G1. The first stencil sheet G1 is subjected to heat-sensitive perforation by selectively performing heat generation of each point-like heating element of the first thermal head 62 based on the first image thinned out in step S201. Making a plate.

  Next, the control unit 20 moves the reading position by the full rate carriage 26 of the image reading unit 2 by one line in the sub-scanning direction (step S203).

  As described above, according to the double-sided stencil printing apparatus 1A according to the second embodiment of the present invention, the thinning process is performed on the first image whose density is corrected, and the thinned first image is processed. Therefore, retransfer can be prevented more compared with the double-sided stencil printing apparatus 1 according to Example 1 of the present invention.

  In the double-sided stencil printing apparatus 1A according to the second embodiment of the present invention, the thinning process is alternately performed for each pixel in the main scanning direction and the sub-scanning direction. A thinning process may be performed for each line.

  In Embodiment 1 of the present invention, when the spread original 101 is printed on both sides of the printing paper W, the double-sided stencil printing apparatus corrects the image density so that the density of the front surface of the printing paper W is lower than the density of the back surface. 1 was described as an example.

  In Embodiment 3 of the present invention, heat reduction is further performed by heating and perforating the first stencil sheet G1 with an applied energy such that the perforation diameter of the first stencil sheet G1 is smaller than the perforation diameter of the second stencil sheet G2. A description will be given by taking as an example a double-sided stencil printing apparatus that performs plate making processing.

<Configuration of double-sided stencil printing machine>
A double-sided stencil printing apparatus 1B according to Example 3 of the present invention has the same configuration as the double-sided stencil printing apparatus 1 according to Example 1 of the present invention shown in FIG.

  Further, the double-sided stencil printing apparatus 1B according to the third embodiment of the present invention is similar to the double-sided stencil printing apparatus 1 according to the first embodiment of the present invention in that the image reading unit 2, the paper feeding unit 3, and the first printing are performed. Part 4, second printing part 5, first plate making part 6, second plate making part 7, first discharging part 8, second discharging part 9, reversing part 10, discharging part A paper unit 11, a RAM 12, a ROM 13, an operation unit 15, and a control unit 20 are provided.

  However, in the double-sided stencil printing apparatus 1B according to the third embodiment of the present invention, the plate-making control unit 20e of the control unit 20 causes the punching diameter of the first stencil sheet G1 to be smaller than the punching diameter of the second stencil sheet G2. It is characterized in that the first stencil making unit 6 is controlled so that the first stencil sheet G1 is heated and perforated with a sufficient applied energy.

<Operation of the double-sided stencil printing apparatus 1B>
Next, the operation of the double-sided stencil printing apparatus 1B according to Example 3 of the present invention will be described.

  FIG. 9 is a flowchart showing a processing flow of the double-sided stencil printing apparatus 1B according to the third embodiment of the present invention. Here, in the flowchart shown in FIG. 9, the processing of steps S101 to S115 and steps S119 to S129 shows the processing flow of the double-sided stencil printing apparatus 1 according to the first embodiment of the present invention shown in FIG. Since the processing contents are the same as those of the processing of the same step number shown in the flowchart, description thereof will be omitted.

  As shown in FIG. 9, when the first image is binarized by the binarization processing unit 20c in step S115, the plate making control unit 20e of the control unit 20 causes the diameter of the first stencil sheet G1 to be punched. Is set such that the first stencil sheet G1 is heated and perforated with an applied energy such that is smaller than the perforation diameter of the second stencil sheet G2 (step S301). Here, the “applied energy” can be expressed as “applied power to the thermal head 62” × “energization pulse width to the thermal head 62”, so that the plate-making control unit 20e can pierce the first stencil sheet G1. Heating is performed by setting at least one of “applied power to thermal head 62” and “energization pulse width to thermal head 62” low so that the hole diameter is smaller than the diameter of the second stencil sheet G2. Set conditions.

  Next, as illustrated in FIG. 9, the plate making control unit 20 e causes the first plate making unit 6 based on the heating condition set in step S <b> 301 and the first image binarized in step S <b> 115. Thus, the first stencil sheet G1 is made for each main scanning line (step S302). Specifically, based on the instruction from the plate making control unit 20e, the first plate making unit 6 causes the first platen roll 63 and the first base paper feed roll 64 to rotate to rotate the first long stencil sheet G1. Each point-like heating element of the first thermal head 62 selectively generates heat based on the first image binarized in step S116 and the heating condition set in step S301. As a result, the first stencil sheet G1 is thermally perforated to make a plate.

  Next, the control unit 20 moves the reading position by the full rate carriage 26 of the image reading unit 2 by one line in the sub-scanning direction (step S303).

  As described above, according to the double-sided stencil printing apparatus 1B according to Example 3 of the present invention, the applied energy is such that the perforation diameter of the first stencil sheet G1 is smaller than the perforation diameter of the second stencil sheet G2. Since the first stencil sheet G1 is heated and perforated (heat reduction plate making process), retransfer can be further prevented as compared with the double-sided stencil printing apparatus 1 according to Example 1 of the present invention.

  In Embodiment 1 of the present invention, when the spread original 101 is printed on both sides of the printing paper W, the double-sided stencil printing apparatus corrects the image density so that the density of the front surface of the printing paper W is lower than the density of the back surface. 1 was described as an example.

  In the fourth embodiment of the present invention, printing is further performed with the pressure of the first press roller 43 in pressure contact with the first drum 41 being smaller than the pressure of the second press roller 53 in pressure contact with the second drum 51. A description will be given by taking as an example a double-sided stencil printing apparatus that executes a reduced-pressure printing process.

<Configuration of double-sided stencil printing machine>
A double-sided stencil printing apparatus 1C according to Example 4 of the present invention has the same configuration as the double-sided stencil printing apparatus 1 according to Example 1 of the present invention shown in FIG.

  Here, the peripheral portion of the first printing unit 4 provided in the double-sided stencil printing apparatus 1C according to the fourth embodiment of the present invention will be described in more detail.

  FIG. 10 is a perspective view of the peripheral portion of the first printing unit 4 of the double-sided stencil printing apparatus 1C according to the fourth embodiment of the present invention.

  As shown in FIG. 10, the cylindrical first drum 41 includes a rotation shaft 45, and this rotation shaft 45 is connected to the main motor via a pulley and a belt. The drum 41 rotates in the direction of the arrow Y1 in the figure. Further, the first drum 41 is provided with a base paper clamp portion 42 so that the leading end of the first stencil base paper G1 made by the first plate making portion 6 is fixed by the base paper clamp portion 42. It has become.

  In addition, a press shaft 47 is provided in parallel with the rotation shaft 45 of the first drum 41, and an external press lever 48 and an internal press lever 49 are attached to the press shaft 47. Further, the press shaft 47 is connected to a bracket 50, and a first press roller 43 is pivotally supported on the bracket 50 so as to be rotatable.

  A hook portion 48a is formed at the front end portion of the press lever 48 on the outer side, and a press spring 122 is connected to the hook portion 48a so as to be urged in the direction of the arrow Y2 in the figure. Due to this urging force, the press shaft 47 is urged to rotate in the direction of the arrow Y3 in the figure, so that the bracket 50 connected to the press shaft 47 rotates to the drum 1 side, and consequently the first shaft. The press roller 43 comes into contact with the first drum 41 with a desired pressure.

  FIG. 11 is a side view of the peripheral portion of the first printing unit 4 of the double-sided stencil printing apparatus 1C according to the fourth embodiment of the present invention.

  As shown in FIG. 11, the end of the press spring 122 is connected to the printing pressure setting mechanism 123. The printing pressure setting mechanism 123 sets a printing pressure setting value supplied from the control unit 20 to be described later, and the printing pressure variable motor 124 provided in the printing pressure setting mechanism 123 applies a printing pressure setting value to the press spring 122. The tension according to is applied.

  FIG. 12 is a functional configuration diagram illustrating a functional configuration of the double-sided stencil printing apparatus 1C according to the fourth embodiment of the present invention.

  A double-sided stencil printing apparatus 1C according to Example 4 of the present invention has the same configuration as the double-sided stencil printing apparatus 1 according to Example 1 of the present invention shown in FIG.

  In addition, the double-sided stencil printing apparatus 1C according to the fourth embodiment of the present invention is similar to the double-sided stencil printing apparatus 1 according to the first embodiment of the present invention in that the image reading unit 2, the paper feeding unit 3, and the first printing are performed. Part 4, second printing part 5, first plate making part 6, second plate making part 7, first discharging part 8, second discharging part 9, reversing part 10, discharging part A paper unit 11, a RAM 12, a ROM 13, an operation unit 15, and a control unit 20C are provided.

  Among these configurations, the configuration other than the control unit 20C is the same as the configuration with the same reference numerals of the double-sided stencil printing apparatus 1 according to the first embodiment of the present invention shown in FIG. Omitted.

  The control unit 20C performs central control of the double-sided stencil printing apparatus 1.

  The control unit 20C includes an image division / allocation unit 20a, a density correction unit 20b, a binarization processing unit 20c, an image thinning unit 20d, a plate making control unit 20e, and a printing pressure control unit 20f. ing.

  Among these configurations, the components other than the printing pressure control unit 20f are configured with the same reference numerals provided in the control unit 20 of the double-sided stencil printing apparatus 1 according to the first embodiment of the present invention illustrated in FIG. Since they are the same, the description thereof is omitted.

  The printing pressure control unit 20 f controls the pressure of the first press roller 43 in pressure contact with the first drum 41 to be smaller than the pressure of the second press roller 53 in pressure contact with the second drum 51.

<Operation of the double-sided stencil printing apparatus 1C>
Next, the operation of the double-sided stencil printing apparatus 1C according to Example 4 of the present invention will be described.

  FIG. 13 is a flowchart showing a processing flow of the double-sided stencil printing apparatus 1C according to the fourth embodiment of the present invention. Here, in the flowchart shown in FIG. 13, the processes of steps S101 to S117, step S119, steps S121 to S125, and steps S127 to S129 are performed on the double-sided stencil printing according to the first embodiment of the present invention shown in FIG. Since the processing contents are the same as the processing of the same step number shown in the flowchart showing the processing flow of the apparatus 1, the description thereof is omitted.

  As shown in FIG. 13, when the reading position of the image reading unit 2 is moved by one line in the sub-scanning direction in step S <b> 117, the printing pressure control unit 20 f of the control unit 20 moves to the first drum 41. Printing conditions are set such that the pressure of the first press roller 43 in pressure contact is smaller than the pressure of the second press roller 53 in pressure contact with the second drum 51 (step S401). Specifically, the printing pressure control unit 30 b is configured such that the pressure of the first press roller 43 that presses against the first drum 41 is smaller than the pressure of the second press roller 53 that presses against the second drum 51. A printing pressure setting value is calculated, and the printing pressure setting value is set in the printing pressure setting mechanism 23 as a printing condition. For example, if the pressure setting value of the second press roller 53 in pressure contact with the second drum 51 is “12” (kgf), the printing pressure setting value of the first press roller 43 in pressure contact with the first drum 41 is set. Set as “9.0” (kgf).

  Next, based on an instruction from the control unit 20, the first printing unit 4 prints the surface of the printing paper W for each main scanning line based on the printing pressure setting value set in step S401 (step S401). S403). Specifically, the first printing unit 4 clamps the leading end of the first stencil sheet G1 conveyed from the first plate making unit 6 with the base paper clamp unit 42, and in this clamped state, the first drum 41 Is rotated so that the first stencil sheet G1 is wound around the outer peripheral surface of the first drum 41. Then, the first printing unit 4 applies the printing paper W fed from the paper feeding unit 3 in synchronization with the rotation of the first drum 41 based on the printing pressure setting value set in step S401. By pressing the first stencil sheet G1 wound around the first drum 41 with one press roller 43, the ink is pushed out from the perforations of the first stencil sheet G1 and the first main scanning one line. Are printed on the surface of the printing apparatus W.

  When it is determined in step S119 that the reading position by the image reading unit 2 has reached the specific position R (in the case of YES), the reversing unit 10 reverses the printing paper W on which the surface is printed (step S405).

  When the second stencil sheet G2 for one line in the main scanning direction is made in step S125, the second printing unit 5 prints the back surface of the printing paper W for one line in the main scanning (step S407). Specifically, the second printing unit 5 clamps the leading end of the second stencil sheet G2 conveyed from the second plate making unit 7 with the base paper clamp unit 52, and in this clamped state, the second drum 51 Is rotated, and the second stencil sheet G2 is wound around and attached to the outer peripheral surface of the second drum 51. The second printing unit 5 winds the printing paper W fed from the reversing unit 10 around the second drum 51 by the second press roller 53 in synchronization with the rotation of the second drum 51. By pressing against the second stencil sheet G2, ink is pushed out from the perforations of the second stencil sheet G2, and a second image for one main scanning line is printed on the back surface of the printing apparatus W.

  As described above, according to the double-sided stencil printing apparatus 1 </ b> C according to the fourth embodiment of the present invention, the pressure of the first press roller 43 that presses against the first drum 41 is pressed against the second drum 51. Since the printing is performed at a pressure lower than the pressure of the press roller 53 (reduced pressure printing process), retransfer can be further prevented as compared with the double-sided stencil printing apparatus 1 according to the first embodiment of the present invention.

  In the second embodiment of the present invention, the double-sided stencil printing apparatus 1A that performs the thinning process and performs the thinning plate making process based on the thinned image will be described as an example. In Example 3, double-sided performing a heat-reducing plate making process for heating and perforating the first stencil sheet G1 with applied energy such that the perforation diameter of the first stencil sheet G1 is smaller than the perforation diameter of the second stencil sheet G2. The stencil printing apparatus 1B will be described as an example. In the fourth embodiment of the present invention, the pressure of the first press roller 43 pressed against the first drum 41 is changed to the second press pressed against the second drum 51. The double-sided stencil printing apparatus 1C that executes the reduced pressure printing process for printing at a pressure lower than the pressure of the roller 53 has been described as an example, but the thinning plate making process, the heat reduction plate making process, and the reduced pressure printing process are executed in combination. It may be.

  Specifically, the first stencil sheet 6 is heated and perforated with applied energy such that the perforation diameter of the first stencil sheet G1 is smaller than the perforation diameter of the second stencil sheet G2. Heat reduction plate making process for generating G1, the first printing unit 4 has the pressure of the first press roller 43 in pressure contact with the first drum 41 provided in the first printing unit 4, the second printing unit 5 The reduced-pressure printing process for printing so as to be smaller than the pressure of the second press roller 53 in pressure contact with the second drum 53 provided, and the image thinning unit 20d is a first image whose density is corrected by the density correction unit 20b. In contrast, at least one of the thinning plate making processes in which the first plate making unit 6 generates the first stencil sheet G1 based on the thinned first image is performed while thinning the image. You can make the process run .

DESCRIPTION OF SYMBOLS 1,1A, 1B, 1C ... Double-sided stencil printing apparatus 2 ... Image reading part 3 ... Paper feed part 4 ... 1st printing part 5 ... 2nd printing part 6 ... 1st plate making part 6 ... Plate making part 7 ... 1st 2 plate-making part 8 ... first discharging part 9 ... photoelectric conversion element 9 ... second discharging part 10 ... reversing part 11 ... discharge part 12 ... RAM
13 ... ROM
DESCRIPTION OF SYMBOLS 15 ... Operation part 20, 20A, 20C ... Control part 20a ... Image division | segmentation allocation part 20b ... Density correction part 20c ... Binarization processing part 20d ... Image thinning part 20e ... Plate making control part 20f ... Printing pressure control part

Claims (3)

First printing means for printing one side of the print medium;
Reversing means for reversing the print medium on which one surface is printed by the first printing means;
Second printing means for printing the other surface of the print medium reversed by the reversing means;
An image reading means for reading an image from a spread document;
Image division assigning means for assigning, as a first image, an image that is approximately half of the spread document that is read first by the image reading means, as a first image;
Density correction means for correcting the density of the first image so that the density of the first image is lower than the density of the second image;
Based on the first image whose density has been corrected by the density correction means, the first printing means generates a first stencil sheet for printing, and the second stencil sheet assigned by the image division assignment means. Plate making means for generating a second stencil sheet for printing by the second printing means based on an image;
A double-sided stencil printing apparatus comprising: Heat-reducing plate making process in which the plate making means generates the first stencil sheet by heating and punching with an applied energy such that the piercing diameter of the first stencil sheet is smaller than the piercing diameter of the second stencil sheet. The second printing unit presses the pressure of the first press roller pressed against the first drum included in the first printing unit against the second drum included in the second printing unit. The reduced-pressure printing process for printing so as to be smaller than the pressure of the press roller, and the image thinning unit thins the image with respect to the first image whose density is corrected by the density correction unit, and the plate making 2. The double-sided image according to claim 1, wherein the means executes at least one of thinning plate making processing for generating the first stencil sheet based on the thinned first image. Stencil stamp Printing device. The image division allocation means includes:
The size of the spread document read by the image reading means is determined. Based on the determined size of the spread document, the first half of the image that is read first is used as the first image, and the size of the spread document to be read later is determined. The double-sided stencil printing apparatus according to claim 1 or 2, wherein substantially half of the image is assigned as the second image.

Images