JP2007331172A - Method and device for detecting front side or back side of master, device for detecting kind of master and printing equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the number of reflective type photo sensors in use to one, realize an inexpensive device, hold the restriction of a mechanical layout in check so as to prevent the mistaken setting of a master from developing by detecting the front side or back side of the master. <P>SOLUTION: This device 23 for detecting the front side or back side of the master is equipped with a single photo sensor 20 for scanningly detecting the front side or back side of the master 10, a master feeding motor 5 and a platen roller 3 for moving the master 10 to the photo sensor 20, an exclusive hardware 24, in which detected voltages concerning the front side or back side of the master 10 detected by the photo sensor 20 are input and processed signally and a judging means 28, which controls the operation of a thermal head 2 through the master feeding motor 5, the LCD displaying part 47 of a console panel 40 and a platemaking controlling part 21 and judges the front side or back side of the master 10 from the difference between the detected voltages input from the exclusive hardware 24. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a printing apparatus including a master front / back detection method, a master front / back detection apparatus, a master type detection apparatus, and a stencil printing apparatus.

Conventionally, digital thermal stencil printing has been known as a simple printing method. This is because a thermal stencil master (hereinafter also simply referred to as “master”) as a printing plate is melted and punched by a thermal head or the like based on read image information of a document image or image information output from a computer such as a personal computer. The master after printing is wound around a plate cylinder outer peripheral surface of a printing drum having a porous cylindrical plate cylinder on the outer peripheral portion for printing. Hereinafter, the plate cylinder is also simply referred to as “printing drum”.
Ink is supplied from the perforated part of the master by supplying ink to the inner peripheral surface of the plate cylinder by the ink supply means provided inside the printing drum and pressing the printing paper against the printing drum by pressing means such as a press roller. The ink image is then transferred to the printing paper, whereby an ink image is formed on the printing paper.

The master has a structure in which a porous fiber film as an ink-permeable porous support is bonded to a thermoplastic resin film (hereinafter also simply referred to as “film”) with an adhesive or the like (hereinafter referred to as “ordinary” Known as “Master”). As the porous fiber membrane, generally a hemp fiber, also called a Japanese paper fiber, or a mixture of hemp fiber and synthetic fiber or wood fiber is used.
However, in the master having such a configuration, a porous support made of fibers is present immediately above the film, so that a large amount of adhesive accumulates in the form of a web of a bird on the part where the fibers overlap and the part where the film contacts. However, in that portion, there was a problem such that punching by a thermal head was difficult to be performed and printing unevenness occurred.

In order to solve such problems, in Japanese Patent Laid-Open No. 10-236011, a porous resin film made of resin is laminated on one surface of a thermoplastic resin film and bonded to each other on the porous resin film. There has been proposed a heat-sensitive stencil master in which a porous fiber film made of a fibrous material is laminated.
The porous resin film means a porous film formed by precipitation of a resin dissolved in a solvent and condensation. Porous fiber membranes are made of thin paper made of fiber materials such as cotton, hemp and other plant fibers, polyester, polyvinyl alcohol and other synthetic materials. The fiber materials are bonded together and entangled or knitted. It means a membrane that is bonded.
According to the heat-sensitive stencil master having such a configuration, problems such as the above-mentioned printing unevenness can be solved, the master's low back force and tensile strength can be improved, and the image quality is also improved.

When a heat-sensitive stencil master having a porous resin film is set on the plate-making unit of a stencil printing machine, if the front and back are reversed, the porous fiber film on the opposite side of the film faces the heating element of the thermal head. As a result, plate-making becomes defective.
It is difficult for an operator or a user (hereinafter referred to as “user”) to visually identify the type of master and to identify the front and back of a heat-sensitive stencil master having a porous resin film. If there is a setting mistake of the thermal stencil master, it is only after at least the first printing is done that it is necessary to discard the master that has been made, replace the master, or reset the master. As well as unnecessary master consumption and a large loss time.

In addition, when the above master having a porous resin film as an intermediate layer is used as a printing plate, due to its unique structure, plate making conditions (such as perforation energy conditions) and printing conditions (ink) are compared to the case of using a normal master. The type of ink and the like due to the difference in ease of passage are greatly different.
For this reason, in a stencil printing apparatus in which conditions are set corresponding to a thermosensitive stencil master having a porous resin film, if printing is performed by setting a normal master in which a porous fiber film is laminated on the film, printing failure will occur. appear. On the other hand, when a stencil printing apparatus in which conditions are set corresponding to a normal master is set with a heat-sensitive stencil master having a porous resin film and printing is performed, printing failure occurs.

Therefore, even if there is a set mistake on the front and back of the heat sensitive stencil master or a set mistake of a different type of master, it can be detected and changed before the plate making, and it can be replaced or re-set, such as waste of master time and lost time Techniques that can prevent the occurrence have been proposed (see, for example, Patent Documents 1 and 2).
That is, in the technique described in Japanese Patent Laid-Open No. 2002-362057, a photo sensor as a reflection type detection unit is provided on each of the front surface side and the back surface side of the master, and the master is specifically determined by the difference in light reflectance from the master. Two reflective photosensors are arranged so as to detect a colored portion and a non-colored portion, respectively, and output voltage output from them according to the difference in light reflectance (Hereinafter referred to as “detection voltage”) is used to identify and determine the front and back of the master and the type of the master, thereby preventing a master set mistake or the like.
For example, when one of the front and back surfaces is colored black, the light reflectance on the black surface side is low, and the detection voltage from the photosensor is accordingly reduced. When the other surface is white, it is opposite to the case of the black surface, and the light reflectance increases, and accordingly, the detection voltage from the photosensor increases accordingly. Since the detection voltage from the photosensor is low on the black surface and high on the white surface, the detection voltage level is detected by two photosensors, and the combination of the two can be used to determine the front and back of the master.

  The technology described in Japanese Patent Application Laid-Open No. 2003-34089 is provided with a color band on one side edge of the master and a corresponding color sensor, thereby detecting a voltage when the color sensor detects the color band, By utilizing the fact that the detected voltage is different when the side edge portion of the heat-sensitive stencil master without a colored band is detected, the front and back of the master are identified and judged to prevent a master set mistake or the like. Furthermore, by providing colored bands of different colors on both side edges of the master and providing a plurality (two or more) of color sensors corresponding thereto, the detection voltage when each color sensor detects the color of the corresponding colored band And the difference in detection voltage when a color of an incompatible color band is detected is used to identify and determine the front and back of the master and the type of the master, thereby preventing a master set mistake or the like.

Japanese Patent Laid-Open No. 2002-362057 JP 2003-34089 A

However, in the technique described in Japanese Patent Application Laid-Open No. 2002-362057 (Patent Document 1), in order to detect the front and back of the master, two photo sensors, a photo sensor for detecting a colored portion and a photo sensor for detecting a non-colored portion. That is, a plurality of photosensors are required. As a result, the number of photosensors used is increased, and the cost thereof is double that when one photosensor is used, so a cost increase is inevitable. Also, a mechanical layout (hereinafter also referred to as “mechanical layout”) for arranging a plurality of photosensors on the plate-making apparatus needs to consider a plurality of locations, which imposes restrictions on the mechanical layout. .
Moreover, in the technique of Unexamined-Japanese-Patent No. 2003-34089 (patent document 2), in order to detect the kind of master, two or more colors corresponding to the colored bands formed in the both-sides edge part of a master differ. A sensor is needed. As a result, as in the technique described in Patent Document 1, the number of color sensors used is increased, and the cost thereof is double that when one color sensor is used, and cost increase is inevitable. In addition, since mechanical layout (mechanical layout) for detection needs to be considered in two places, the mechanical layout is restricted.

Therefore, the present invention has been made in view of the above-described circumstances, and the number of reflection type detection means (reflection type photosensors) is reduced to one, so that the cost of the mechanical layout can be suppressed at a low cost. The first object of the present invention is to provide a printing device including a master front / back surface detection method, a master front / back surface detection device, a stencil printing device, and the like that can detect the front and back surfaces of the master and prevent a master set error.
Color detection means (photo sensor / color sensor) that detects coloring of a colored master enables identification of the master by color, thereby detecting the type of master and preventing missetting of different masters. It is a second object of the present invention to provide a printing apparatus including a master type detection apparatus and a stencil printing apparatus that can improve machine performance by enabling optimal setting of a master.

In order to solve the above-described problems and achieve the above-described object, the invention according to each claim employs the following characteristic means / invention specific matters (hereinafter referred to as “configuration”).
The invention according to claim 1 arranges a single reflection type detection means on the front side or back side of the master provided with either one of the thermoplastic resin film and the porous support on the front side or back side, By relatively moving either one of the master and the reflection type detection means, the surface or the back surface of the master is scanned with the reflection type detection means, and the reflection type at a plurality of locations on the surface or the back surface of the scanned master The master front / back detection method is characterized in that the front / back of the master is determined from a difference in output signal values from the detection means.

  According to a second aspect of the present invention, in the master front / back detection method according to the first aspect, when the reflective detection means is arranged to detect the thermoplastic resin film surface side, the output from the reflective detection means It is characterized in that the front and back of the master are judged from the small difference in signal value.

  According to a third aspect of the present invention, in the master front / back detection method according to the first aspect, an output signal from the reflective detection means when the reflective detection means is arranged to detect the porous support surface side. It is characterized in that the front and back of the master are judged from the large difference in values.

  The invention according to claim 4 is a single reflection type detecting means arranged on the front side or the back side of the master provided with either one of the thermoplastic resin film and the porous support on the front side or the back side, A moving unit that moves one of the master and the reflection type detection unit with respect to the other, and the reflection type at a plurality of locations on the front or back surface of the master scanned by the reflection type detection unit via the movement unit A master front / back detection apparatus comprising: a determination unit configured to determine the front / back of a master from a difference between output signal values from the detection unit.

  According to a fifth aspect of the present invention, in the master front / back surface detection apparatus according to the fourth aspect, when the reflection type detection means is arranged to detect the thermoplastic resin film surface side, the determination means is the reflection type It is characterized in that the front and back of the master are determined from the small difference in the output signal values from the detection means.

  According to a sixth aspect of the present invention, in the master front / back surface detecting device according to the fourth aspect, when the reflective detection means is arranged to detect the porous support surface side, the determination means is configured to detect the reflective detection means. It is characterized in that the front and back of the master are determined from the large difference in the output signal values from the means.

  The invention according to claim 7 is the master front / back detection device according to any one of claims 4 to 6, wherein the determination unit calculates a difference between the output signal values at the plurality of locations from the reflection type detection unit. The output signal value is obtained by intermittent sampling.

  According to an eighth aspect of the present invention, in the master front / back surface detection device according to any one of the fourth to sixth aspects, the determination unit calculates a difference between the output signal values at the plurality of locations from the reflection type detection unit. The output signal value is obtained by sampling continuously.

  According to a ninth aspect of the present invention, in the master front / back surface detection device according to any one of the fourth to eighth aspects, the reflection type detection means has a peak emission wavelength characteristic at a wavelength according to the coloring of the colored master. And a light receiving element having a peak sensitivity wavelength characteristic at a wavelength of reflected light from a colored portion of the master, and also has a function of detecting coloring of the colored master, and the determination means includes the reflective detection The type of the master is also determined based on the output signal from the means.

  A tenth aspect of the present invention is a master type detection apparatus comprising: color detection means for detecting coloring of a colored master; and determination means for determining a master type based on an output signal from the color detection means. The color detecting means includes a light emitting element having a peak emission wavelength characteristic at a wavelength corresponding to coloring of the master, and a light receiving element having a peak sensitivity wavelength characteristic at a wavelength of reflected light from the colored portion of the master. It is characterized by that.

  The invention according to claim 11 has the master front / back detection device according to any one of claims 4 to 9 or the master type detection device according to claim 10, and makes a master according to image information. And a printing drum that winds a pre-made master around the outer peripheral surface, and printing is performed by directly or indirectly pressing a printing medium on the pre-made master on the printing drum. This is a printing apparatus.

According to the present invention, it is possible to provide a novel master front / back surface detection method, master front / back surface detection device, master type detection device, and printing device by solving the above problems. The effects of the invention for each claim are as follows.
According to the first and fourth aspects of the present invention, with the above-described configuration, a single reflection type detection unit (for example, a photo sensor) is used to detect the front and back of the master with two reflection type detection units. Therefore, the number of reflection type detection means can be reduced to one, the cost thereof is halved, mechanical layout restrictions are halved, and a master set error can be prevented.

  According to the second and fifth aspects of the present invention, when the reflection type detection means is arranged to detect the thermoplastic resin film surface side, a difference in output signal value (for example, detection voltage) from the reflection type detection means. By determining the front and back of the master from the smallness of the output signal value, that is, the variation in the output signal value, the fluctuation range of the output signal value is narrowed. In the data processing of the output signal, digitization by A / D conversion is usually performed, but since the fluctuation range of the output signal value is narrow, the cost can be reduced by using a low-bit one at the time of this A / D conversion. The effect that can also be achieved.

  According to the third and sixth aspects of the invention, when the reflection type detection means is arranged so as to detect the porous support surface side, the difference between the output signal values from the reflection type detection means is large. By judging the front and back, for example, when the thermoplastic resin film surface constitutes an internally wound roll master (for example, master roll), the porous support surface is outside the roll master. Although it depends on the arrangement of the (thermal head), when the plate making means is arranged on the lower side of the master, there is a design margin when considering the mechanical layout of the reflection type detecting means arrangement. It's easy to do. Further, since the reflection type detecting means is arranged on the upper side of the master, there is an effect that malfunctions are less likely to occur due to adhesion of the master powder or dust.

According to the seventh aspect of the present invention, the judging means obtains the difference between the output signal values at a plurality of locations by intermittently sampling the output signal value from the reflection type detecting means, thereby obtaining the output signal value (for example, detection). The number of data of the voltage) can be reduced, whereby the control configuration can be simplified and the processing time required for the determination can be shortened.
According to the eighth aspect of the present invention, the determination means obtains the difference between the output signal values at a plurality of locations by continuously sampling the output signal values from the reflection type detection means, thereby obtaining the master characteristic, that is, the thermoplasticity. Since the smoothness of the resin film surface and the fiber unevenness of the porous support surface are not missed, the determination accuracy when determining the front and back of the master is improved.

According to the ninth aspect of the present invention, the configuration enables the detection of the color of the colored master together with the effect of the fourth aspect of the invention, thereby enabling the identification of the master by color. Since the master type can also be detected, setting errors of different masters can be reduced, and the optimum setting of the masters can be performed, thereby improving the machine performance.
According to the tenth aspect of the present invention, since the color of the colored master can be detected by the above configuration, the master can be identified by the color, and thus the type of the master can be detected. As a result, setting errors of different masters can be reduced, and the optimum setting of the masters can be performed, so that the machine performance is improved.
According to the eleventh aspect of the present invention, the printing apparatus having the above configuration has the effects of the above-described inventions.

  The best mode for carrying out the invention including examples will be described below with reference to the drawings (hereinafter referred to as “embodiments”). In each embodiment and the like, components (members and components) having the same function, shape, and the like will be omitted by giving the same reference numerals after being described once. When quoting and explaining constituent elements such as published patent gazettes, the reference numerals are shown in parentheses to distinguish them from those of the embodiments.

(First embodiment)
The first embodiment will be described with reference to FIGS. First, an overall configuration of a digital heat-sensitive stencil type plate making apparatus according to a first embodiment and a stencil printing apparatus as an example of a printing apparatus including the plate making apparatus will be described with reference to FIG.
In FIG. 1, reference numeral 50 denotes an apparatus main body that forms the framework of the stencil printing apparatus. In the upper part of the apparatus main body 50, the part indicated by reference numeral 80 is a document reading apparatus, the part indicated by reference numeral 1 below is a plate making apparatus having the master front / back detection device of the present invention, and the part indicated by reference numeral 100 on the left is porous A printing drum apparatus provided with a printing drum 101 having a cylindrical plate cylinder on the outer periphery, a portion denoted by reference numeral 70 on the left of the printing drum apparatus, a portion denoted by reference numeral 110 below the plate making apparatus 1 is a sheet feeding device, A portion indicated by reference numeral 120 below the printing drum 101 indicates a printing pressure device, and a portion indicated by reference numeral 130 on the lower left side of the apparatus main body 50 indicates a paper discharge device.

Next, with respect to the main configuration and basic overall operation of the stencil printing apparatus shown in FIG. 1, an enlarged view of the main part of the plate making apparatus 1 shown in FIG. 2, the operation panel 40 shown in FIG. 3, and the stencil printing shown in FIG. This will be described with reference to a block diagram of the apparatus.
A document 60 having an image to be printed is placed on a document placing table (not shown) disposed at the top of the document reading device 80, and the plate making start key 41 of the operation panel 40 is pressed. A start signal generated when the plate making start key 41 is pressed serves as a trigger, and a plate discharging process is first executed. That is, in this state, the used master 10 used in the previous printing remains attached to the outer peripheral surface of the printing drum 101 of the printing drum apparatus 100.

  When the printing drum 101 rotates counterclockwise and the rear end of the used master 10 on the outer circumferential surface of the printing drum 101 approaches the plate release roller pair 71a, 71b in the plate release device 70, the roller pair 71a, 71b While rotating, the rear end portion of the used master 10 is scooped up by one discharged plate peeling roller 71b. The used master 10 scooped up at the rear end is stretched between a pair of discharge plate rollers 73a and 73b disposed on the left side of the pair of discharge plate peeling rollers 71a and 71b and the pair of discharge plate peeling rollers 71a and 71b. While being conveyed in the direction of arrow Y 1 by the pair of discharged plate conveying belts 72 a and 72 b, the discharged master is discharged into the discharged plate box 74, and the used master 10 is completely peeled off from the outer peripheral surface of the printing drum 101 and stored in the discharged plate box 74. Then, the plate removal process is completed. At this time, the printing drum 101 continues to rotate counterclockwise. The used master 10 that has been peeled and discharged is then compressed inside the discharge box 74 by the compression plate 75.

  In parallel with the plate removal process, the document reader 80 reads the document. That is, the document 60 placed on a document placement table (not shown) is conveyed in the directions of arrows Y2 to Y3 by the rotation of the separation roller 81, the front document conveyance roller pair 82a and 82b, and the rear document conveyance roller pair 83a and 83b. While being used for exposure reading. At this time, when there are a large number of documents 60, only the lowermost document is conveyed by the action of the separating blade 84. When reading the image of the original 60, the reflected light from the surface of the original 60 illuminated by the fluorescent lamp 86 while being transported on the contact glass 85 is reflected by the mirror 87 and passes through the lens 88, and then the CCD (photocoupler such as a charge coupled device) is read. This is performed by being incident on an image sensor 89 formed of a conversion element. The document 60 from which the image has been read is discharged onto the document tray 80A.

The optical information of the document 60 is photoelectrically converted by the image sensor 89, and the analog electric signal is input to an analog / digital (A / D) converter (not shown) in the apparatus main body 50 to be converted into a digital image signal. . The digital image signal is subjected to image processing by an image processing unit (not shown), and the image signal thus subjected to image processing is input to the plate making control unit 21 shown in FIG. The image signal input to the plate making control unit 21 is subjected to appropriate control processing and then transmitted to the thermal head 2 via a thermal head driving circuit (not shown).
Note that the image signal input to the plate making control unit 21 via the image processing unit is not limited to the one read by the image sensor 89 formed of a CCD, for example, one read by an image sensor such as a contact sensor, a personal computer, or the like It may be an image signal transmitted from the computer.

  On the other hand, in parallel with this image reading operation, plate making and plate feeding processes are performed based on image information (image data signal) converted into digital signals. That is, the master 10 is set so that the master 10 can be fed out via the master support member 22 shown in FIG. 2 arranged at a predetermined portion of the plate making apparatus 1, and is wound around the core tube 10a in a roll shape. The platen roller 3 pulled out from the master roll 10A and pressed against the thermal head 2 via the master 10 and the pair of tension rollers 4a and 4b are rotated downstream of the sub-scanning direction Y, which is the master transport direction. Be transported. A large number of minute heating elements (not shown) arranged in a line in the main scanning direction perpendicular to the sub-scanning direction Y of the thermal head 2 are supplied from the plate making control unit to the master 10 thus conveyed. The thermoplastic resin film portion of the master 10 that is selectively heated according to the data signal sent and is in contact with the generated heating element through a protective film layer (not shown) is heated, melted and perforated. . In this way, image information is written in the master 10 as a drilling pattern by position-selective melt drilling of the master 10 according to the image information. The thermal head 2 has a known function as plate making means for making the master 10 in accordance with image information.

A single unit that detects the front and back of the master 10 on the upstream side in the sub-scanning direction Y of the thermal head 2, that is, between the master support member 22 and the thermal head 2 and on the master transport path near the master support member 22. A reflection type photosensor 20 is disposed as a reflection type detection means.
The photosensor 20 receives light reflected from the front surface or the back surface of the master 10 and a light emitting element made of, for example, a light emitting diode (LED), for emitting light to the front surface or the back surface of the master 10 that is a detection target. And a light-receiving element made of a phototransistor, and has a well-known configuration in which these are housed in one package case.
The configuration around the thermal head 2, the platen roller 3, the master 10, and the photosensor 20 will be described in detail later.

The platen roller 3 is connected to a master feed motor 5 via a rotation transmission member (not shown) such as a timing belt and a gear, and is rotated by the master feed motor 5. The master feed motor 5 is composed of, for example, a stepping motor. The rotational driving force of the master feed motor 5 is applied to the tension roller pair 4a, 4b via a tension transmission pair (4a, 4b) and an electromagnetic clutch (not shown) via a rotation transmission member (not shown) such as a gear. Further, it is transmitted to a pair of upper and lower reversing rollers 7a and 7b arranged on the downstream side in the sub-scanning direction Y.
Here, the platen roller 3, the rotation transmission member, and the master feed motor 5 constitute a moving unit that moves the master 10 relative to the photosensor 20. In the present embodiment, the use of the moving means that has been conventionally provided in the plate making apparatus 1 has an advantage and an effect that its configuration is simple and inexpensive.
Note that the moving means is not limited to the above-described one as long as the advantages / effects are not desired so much, for example, by moving the photosensor 20 with respect to the master 10 in a stationary state. The front or back surface may be scanned.
As an example of moving the photosensor 20 side, a rack disposed and fixed near the upper side of the master 10, a pair of pinions meshing with the rack, a pair of pinions are rotatably supported, and the photosensor 20 is also supported. There is a moving means composed of a mounted sensor moving table and a stepping motor provided on the sensor moving table and driving the pair of pinions through a driving force transmitting member such as a belt and a pulley. .

The leading end of the master 10 having image information written thereon is sent out toward the outer peripheral side of the printing drum 101 by the pair of reverse rollers 7 a and 7 b while being guided on the guide plate 8, and proceeds by the plate supply guide plate 9. The direction is changed downward and hangs down toward the master clamper 102 (indicated by a two-dot chain line) of the printing drum 101 in the plate feeding position state shown in the drawing. At this time, the used master 10 has already been removed from the printing drum 101 by the discharging process.
When the leading end of the master 10 that has been made is clamped by the master clamper 102 at a certain timing, the printing drum 101 rotates the master 10 that has been made on the outer peripheral surface while rotating in the direction A (clockwise direction) in the figure. Wrap gradually. The rear end of the master 10 that has been subjected to plate making is cut into a fixed length by the cutter 6.

When the master 10 for one plate has been wound around the outer peripheral surface of the printing drum 101, the plate making and plate feeding steps are completed, and the printing step is started. First, the uppermost one of the printing papers 62 as the printing medium stacked on the paper feed tray 51 is directed toward the registration roller pairs 113a and 113b by the paper feed roller 111 and the separation roller pairs 112a and 112b. The sheet is fed in the direction of the arrow Y4, and further sent to the printing pressure device 120 at a predetermined timing synchronized with the rotation of the printing drum 101 by the registration roller pair 113a and 113b. When the fed printing paper 62 comes between the printing drum 101 and the press roller 103, the press roller 103 that has been separated below the outer peripheral surface of the printing drum 101 is moved upward, whereby the printing drum 101. It is pressed by the master 10 that has been pre-rolled around the outer peripheral surface. In this way, ink oozes out from the perforated portion of the printing drum 101 and the perforated pattern portion (not shown) of the master 10 that has been made, and the oozed ink is transferred to the surface of the printing paper 62 to form a printed image. Is done.
At this time, on the inner peripheral side of the printing drum 101, ink is supplied from the ink supply pipe 104 to the ink reservoir 107 formed between the ink roller 105 and the doctor roller 106, and in the same direction as the rotation direction of the printing drum 101. Ink is supplied to the inner peripheral side of the printing drum 101 by the ink roller 105 that is in contact with the inner peripheral surface while rotating in synchronization with the rotation speed of the printing drum 101. The ink supply tube 104, the ink roller 105, and the doctor roller 106 constitute an ink supply unit that supplies ink to the master 10 that has been made on the printing drum 101.

The printing paper 62 on which the printing image is formed in the printing pressure device 120 is peeled off from the print drum 101 by the paper discharge peeling claw 114 in the paper discharge device 130 and sucked by the suction fan 118, while the suction paper discharge inlet roller 115 and By the counterclockwise rotation of the conveyor belt 117 stretched around the suction discharge outlet roller 116, it is conveyed toward the discharge tray 52 as indicated by an arrow Y5, and is sequentially discharged and stacked on the discharge tray 52. In this way, so-called plate printing is completed.
Next, when the number of prints is set with the numeric keypad 43 of the operation panel 40 and the print start key 42 is pressed, the steps of paper feeding, printing and paper discharge are repeated for the set number of prints in the same process as the plate printing. This completes the entire stencil printing process.

The configuration of the plate making apparatus 1 and the operation panel 40 will be supplementarily described.
As shown in FIG. 2, the core tube 10a of the master roll 10A protrudes outward from both end faces of the master roll 10A, and a master support member 22 arranged in a pair on the front side and the back side of the paper surface 10 is rotatably supported so as to be extended in the sub-scanning direction Y. The master roll 10 </ b> A is a so-called film in-plane winding in which a surface of a thermoplastic resin film (hereinafter also simply referred to as “film”) constituting the master 10 is wound inside. Therefore, the lower surface of the master 10 fed out from the master roll 10 </ b> A in the sub-scanning direction Y is on the film side in contact with a heating element (not shown) of the thermal head 2.
As shown by the solid lines in FIGS. 1 and 2, the single photosensor 20 is arranged to detect the porous support side of the master 10.

The operation panel 40 is disposed on one side of the upper part of the document reading device 80. As shown in FIG. 3, the operation panel 40 includes a plate making start key 41, a printing start key 42, a ten key 43, a trial printing key 44, an enter key 45, a clear / stop key 46, and an LCD (Liquid Crystal Display) display unit 47. Also, a number indicator 48 and the like for displaying the number of printed sheets and the like are arranged.
The plate making start key 41 functions as an operation starting means for starting a series of steps (operations) from reading of an image of a document to plate discharge, plate making, plate feeding, paper feeding, plate printing, and paper discharge steps. The numeric keypad 43 is a function for inputting / setting the number of prints, the print start key 42 is a function for starting the printing operation for the number of prints input / set by the numeric keypad 43, and the test printing key 44 is Each has a function of starting a test printing operation.
The LCD display unit 47 is driven through an LCD drive circuit (not shown), displays warnings on the front and back surfaces of the master 10, warnings such as jams on the master 10 and the printing paper 62, and the like of each device unit in the stencil printing apparatus. It has a function as display means (notification means) for displaying (notifying) a state or the like.

As shown in FIG. 5, the master 10 used in the present embodiment includes a porous resin film 12 made of a thermoplastic resin and a fibrous material bonded to each other on one surface of a thermoplastic resin film 11. It has a three-layer structure in which a porous fiber film 13 as a porous support is formed. The porous support is also called a porous membrane.
The porous resin film 12 is composed of a resin film component 12a and a gap 12b. The porous resin film 12 is formed by precipitating and condensing a resin dissolved in a solvent, and has a structure having a large number of voids 12b inside and on the surface of the film.
From the viewpoint of ink permeability, it is desirable that the gap 12b is continuous in the thickness direction in the film, and the gap 12b penetrates in the ceiling direction when the thermoplastic resin film 11 is a floor.

As the resin that is a main component of the material of the porous resin film 12, those described in the paragraph number “0035” of the above-mentioned JP-A-2002-362057 are used. A filler may be added to the resin solution in the manufacturing process of the porous resin film 12 as necessary. This addition affects the shape, strength, and pore size of the porous resin film produced during the drying process. Specific examples include inorganic compounds such as zinc oxide, titanium dioxide, calcium carbide, and silica, and organic polymer particles such as polyvinyl acetate, polyvinyl chloride, and polymethyl acrylate. Microcapsules and Matsumoto Microfire (Matsumoto Yushi Seiyaku Co., Ltd.) can also be used effectively.
Furthermore, an antistatic agent, a stick preventing agent, a surfactant, a preservative, an antifoaming agent, and the like can be used in combination with the porous resin film 12 as long as perforation is not inhibited.

As the thermoplastic resin film 11, what is conventionally used for the master, such as a vinyl chloride-vinylidene chloride copolymer film, a polypropylene film, and a polyester film, can be used.
Further, a stick prevention layer for preventing sticking with the thermal head 2 can be provided on the surface of the film 11. In this case, as the anti-sticking agent used, those generally used in conventional masters can be used. For example, silicone release agents, fluorine release agents, phosphate ester surfactants, and the like can be used.

The porous fiber membrane 13 is manufactured by a known method. Examples of the porous fiber membrane 13 include various fibers or fibrous materials described in paragraph No. “0038” of JP-A-2002-362057.
A porous membrane (porous support) includes fibers such as Japanese paper, a porous sheet, a mesh sheet, and the like. The porous fiber film 13 including the embodiments described later will be specifically described as being composed of, for example, Japanese paper fibers.
The color of the thermoplastic resin film 11 is transparent, and the color of the porous resin film 12 is white due to the manufacturing method. The porous resin film 12 has a structure in which fine voids are complicatedly overlapped in the thickness direction, and the light permeability is poor. For this reason, even if the porous fiber film 13 is observed from the porous resin film 12 side, the porous fiber film 13 is hardly visible.

Next, with reference to FIG. 4, the master front / back detection device 23 for detecting the front / back of the master 10 will be described in detail. As shown by a one-dot chain line in FIG. 4, the master front / back detection device 23 scans the front surface or the back surface of the master 10 and detects the single photosensor 20, and moves the master 10 relative to the photosensor 20. An output signal relating to the front or back surface of the master 10 detected by the master feed motor 5 and the platen roller 3 constituting the moving means and the photo sensor 20, that is, a detection voltage from the photo sensor 20, is inputted, and signal processing described later is performed. For controlling the operation of the thermal head 2 via the master H / W 24, the master feed motor 5, the LCD display 47 of the operation panel 40 and the plate making control unit 21, and the detection voltage input from the dedicated H / W 24 It is mainly comprised from the judgment means 28 which judges the front and back of the master 10 from the difference of these.
The plate making apparatus 1 has a master front / back detection device 23. Here, “the plate making apparatus 1 has the master front / back detection device 23” means that the dedicated H / W (dedicated hardware) 24 and the determination means 28 which are control components of the master front / back detection device 23 described later are not necessarily plate-making. It does not mean that it is arranged in the apparatus 1, and includes being electrically connected and arranged via a signal line or an electric wire to a control board or the like in the apparatus main body 50 arranged outside the plate making apparatus 1. This means that it belongs to the plate making apparatus 1 substantially.

The photosensor 20 is electrically connected to the dedicated H / W 24 via a signal line. More specifically, as the photosensor 20, the master 10 used in the present embodiment is non-colored, transparent or white (hereinafter referred to as “white”) as described above, and infrared light is human. Infrared sensors are preferably used because they do not interfere with the eyes, have a larger light emission output than visible LEDs, and are close to the sensitivity wavelength of the phototransistor on the light receiving element side.
The photosensor 20 made of an infrared sensor generates infrared light (for example, infrared light having a wavelength of 905 nm), and a light emitting element made of an infrared LED that emits the infrared light to the front or back surface of the master 10 that is a detection target. And a light receiving element made of a phototransistor that amplifies a voltage corresponding to the reflected light and outputs it as a detection voltage.
Since the infrared sensor is used for the photosensor 20 as described above, the photosensor 20 corresponds to the density (brightness) of the master regardless of the color, and the light reflectance (corresponding to the monochrome density) A detection voltage corresponding to the amount of reflected light is amplified from the light receiving element and output. It is not the color that reacts to the infrared rays emitted from the light emitting element of the photosensor 20, but in the case of a density that returns reflected light to the light receiving element as in the case of the uncolored or white master 10, such as blue or red Note that the photosensor 20 cannot identify the color because it does not respond to chromatic colors.

The dedicated H / W 24 is an A / D converter 25 that converts an analog detection voltage value (output signal value) from the photosensor 20 into a digital value, and a holding unit that temporarily holds the converted digital value. It is mainly composed of a register 26 and arithmetic means 27 for calculating a plurality of digital values held in the register 26 to obtain a difference in detected voltage (difference in output signal value) and the like. The computing means 27 is composed of a subtracting circuit, for example. The holding means may be a RAM.
The dedicated H / W 24 is electrically connected to the determination means 28 via a signal line. The difference between the detection voltages calculated by the calculation unit 27 of the dedicated H / W 24 is input to the determination unit 28.

The determination unit 28 is configured by including a microcomputer including a CPU, a ROM, a RAM, an I / O interface, and the like. The CPU has a control function in addition to the calculation function. The determination means 28 determines the front and back of the master 10 from the difference between the input detection voltages based on the operation program called from the ROM and related data, and the master feed motor 5, the LCD display section 47 of the operation panel 40, and It has a function of controlling the thermal head 2 through the plate making control unit 21 as described later.
Further, the determination unit 28 has a function of obtaining the difference between the detection voltages at the plurality of locations by sampling (extracting) the detection voltage from the photosensor 20 intermittently (discretely) via the dedicated H / W 24. . The determination means 28 is not limited to the function obtained by sampling intermittently, but the sampling voltage from the photosensor 20 is continuously sampled through the dedicated H / W 24 to detect the difference between the detection voltages at the plurality of locations. The required function may be provided.
The ROM of the determination unit 28 stores an operation program and related data for controlling the thermal head 2 via the master feed motor 5, the dedicated H / W 24, the LCD display unit 47 of the operation panel 40 and the plate making control unit 21. The operation program and related data are appropriately called up by the CPU of the determination means 28. The RAM of the determination unit 28 has a function of temporarily storing the calculation result of the CPU.

In the control configuration shown in FIG. 4, the detection voltage transmitted from the photosensor 20 is an analog value. Therefore, the conversion to a digital value takes into account the influence of noise or the like and the calculation by the calculation means 27 in post-processing. Is advantageous. The A / D conversion of the sampling data related to the detection voltage may use analog input of the CPU of the determination unit 28, but it is preferable to perform the dedicated H / W 24 in consideration of processing speed and load.
Therefore, if it is not necessary to consider the processing speed and load so much, the dedicated H / W 24 register 26 and arithmetic means 27 shown in FIG. 4 are removed, and a microcomputer is provided. The photosensor 20 may be electrically connected to the input port of the determination unit 28 that can also be referred to as a control device, and processing similar to that performed by the register 26 and the calculation unit 27 may be performed on the determination unit 28 side.

  In addition to the control configuration shown in FIG. 4, for example, the entire control target driving means (referring to a control target motor or solenoid actuator) of each device / unit of the stencil printing apparatus shown in FIG. 1 is controlled. The main control device (main control means: not shown) and the judgment means 28 may be connected so as to be able to transmit and receive, and the operation of the master feed motor 5 may be controlled on the main control device side. That is, using the start signal of the plate making start key 41 of the operation panel 40 as a trigger, the master feed motor 5 is rotationally driven and controlled according to the sequence at the time of the plate making operation described above, the photo sensor 20 is used to control the master 10. You may make it carry out the distance scanning required for the detection of front and back.

Next, the operation of the master front / back surface detection device 23 will be described with reference to FIGS. 1 to 6.
When a power switch (not shown) for supplying power to each device / part of the stencil printing apparatus is turned on, power is supplied to the photosensor 20, the dedicated H / W 24, and the judging means 28 of the master front / back surface detection device 23. At the same time, the plate making control unit 21, the thermal head 2, the master feed motor 5, and other devices / units are prepared for power supply and ready for operation. The platen roller 3 and the tension roller pair 4a are activated when the master feed motor 5 is started by using a start signal generated by pressing the plate making start key 41 during the above-described plate discharging and plate making operations or after the master roll 10A is replaced. , 4b are rotated. As a result, the master 10 is pulled out from the master roll 10 </ b> A and conveyed downstream in the sub-scanning direction Y.

At this time, the porous fiber membrane 13 surface of the master 10 is detected by a single photosensor 20 arranged to scan and detect the porous fiber membrane 13 surface side as shown by a solid line in FIGS. The scan detection voltage waveform of the photosensor 20 when scanning is as shown in FIG. 5A in the embodiment.
On the surface side of the porous fiber film 13, there is a density difference due to fiber unevenness (roughness / density) such as Japanese paper fiber, so that the fluctuation range of the detection voltage of the photosensor 20 is large, for example, as shown in FIG. Furthermore, the maximum (maximum) detection voltage was 3.2 V and the min (minimum) detection voltage was 0.8 V, and the fluctuation range of the detection voltage was increased. The fluctuation range was max-min = 3.2-0.8 = 2.4V.
In addition, when three locations indicated by broken lines are intermittently sampled in the scanning section of the photosensor 20, each detected voltage becomes 2.5V⇔1.8V⇔2.0V, and the voltage fluctuation due to the sampling position is Δ0. 0.7V and Δ0.2V.

On the other hand, the scanning detection voltage waveform of the photosensor 20 when the surface of the film 10 of the master 10 is scanned is as shown in FIG.
Since the surface of the film 11 has good smoothness, the variation range of the detection voltage of the photosensor 20 is small. For example, as shown in FIG. 5C, the maximum (maximum) detection voltage is 2.3 V, min ( Minimum) The detection voltage is 1.7 V, and the width of the fluctuation is max-min = 2.3-1.7 = 0.6 V. The width of the detection voltage fluctuation when scanning the porous fiber membrane 13 surface is 2.4 V. The width of variation was smaller than that of.
In addition, when three locations indicated by broken lines are intermittently sampled in the scanning section of the photosensor 20, each detected voltage becomes 1.8V⇔1.9V⇔2.1V, and the voltage fluctuation due to the sampling position is Δ0. .1V and Δ0.2V.

As described above, when the surface of the porous fiber film 13 of the master 10 is scanned, there is a density difference due to fiber unevenness (roughness / denseness), so that the detection voltage of the photosensor 20 varies greatly depending on the detection position / location of the master 10. As a result, a large variation in the detection position was obtained. On the other hand, when the film 11 surface side is scanned, the smoothness is good, so that the detection voltage of the photosensor 20 is less varied depending on the detection position / location of the master 10, and the variation due to the detection position is small. It was.
As described above, when the surface of the porous fiber membrane 13 and the surface of the film 11 of the master 10 are scanned with the photosensor 20 continuously or intermittently, the fluctuation widths of the detected voltages are different. By determining the fluctuation range (variation width) by the determination unit 28 via the dedicated H / W 24, the front and back of the master 10 can be determined.

  The detected voltage waveform of the photosensor 20 shown in FIGS. 5A and 5C is obtained when the surface of the porous fiber film 13 and the surface of the film 11 of the master 10 having the three-layer structure is actually applied to the photosensor 20 (specifically , The detected voltage waveform when scanned by an infrared sensor is simplified. Further, the scanning distance (moving distance of the master 10) when the photo sensor 20 scans the surface of the porous fiber membrane 13 (or the surface of the film 11) of the master 10 is sufficient if it is in the range of about 4 to 5 mm.

Next, a method for obtaining the difference between the detection voltages at the plurality of locations (three locations in this embodiment) by sampling the detection voltage from the photosensor 20 intermittently and discretely will be described. The detection voltage output from the photosensor 20 at each sampling position of the master 10 is output to the register 26 via the A / D converter 25 of the dedicated H / W 24, and is held by the register 26, and then the calculation means 27. The comparison / difference calculation of the held detection voltage data is performed.
As described with reference to FIG. 5, when the case of three sampling positions is considered, there is detected voltage data at three sampling positions. First, when the surface of the porous fiber membrane 13 is scanned, the detection voltage at each sampling position is 2.5V⇔1.8V⇔2.0V. From this, when the voltage fluctuation depending on the sampling position is obtained, (2.5−1.8) = Δ0.7V, (1.8−2.0) = Δ−0.2V, (2.0−2.5) = Δ−0.5V. Thus, the large difference in the detection voltage between the sampling positions indicates that the fluctuation range (variation width) of the detection voltage is large.

Next, considering the case where the surface of the film 11 is scanned, the detection voltage at each sampling position is 1.8V⇔1.9V⇔2.1V. From this, when voltage fluctuations due to sampling positions are obtained, (1.8-1.9) = Δ−0.1V, (1.9−2.1) = Δ−0.2V, (2.1-1. 8) = Δ0.3V. Thus, a small difference in detection voltage between sampling positions indicates that the fluctuation range (variation width) of the detection voltage is small.
The above-described difference in detection voltage is signed (±), but it may be an absolute value comparison.

Considering the case where the maximum value of the fluctuation range (variation width) of the detection voltage in absolute value, that is, the maximum difference is obtained and compared, for example, when Δ0.5V or more, the fluctuation range (variation width) is large. It can be determined that the fluctuation range is large on the porous fiber membrane 13 side and the fluctuation range is small on the film 11 side. As an example, assuming that the following determination formula is used, the maximum difference is obtained and compared.
Judgment formula: When fluctuation width (variation width) is large = variation width ≧ threshold value According to the above judgment formula, on the porous fiber membrane 13 surface side, a maximum difference of 0.7 ≧ 0.5 is established. It can be determined that the width (variation width) is large.
On the other hand, on the film 11 surface side, the maximum difference is 0.3 ≦ 0.5, and the above-described determination formula does not hold, so it can be determined that the fluctuation range (variation width) of the detection voltage is small.
The determination means 28 performs the calculation / comparison based on the determination formula as described above, and recognizes / determines that the larger fluctuation width (variation width) is the surface of the porous fiber membrane 13, and the fluctuation width (variation width) is larger. The smaller one can recognize and judge that it is the film 11 surface, and comprehensively determine the front and back of the master 10 from the balance between the determination result and the arrangement of the photosensor 20 on the front and back surfaces of the master 10. .

That is, based on the determination result, when the determination unit 28 recognizes / determines that the detection voltage is on the film 11 side because the fluctuation range of the detection voltage is small, the photosensor 20 is shown as a solid line in FIG. 1 and FIG. From the point of being arranged to detect the porous fiber membrane 13 surface side, it is comprehensively determined that the front and back of the master 10 are reversed and not set properly, and through the plate making control unit 21 At the same time as the thermal head 2 is stopped, the rotation of the master feed motor 5 is stopped, and the LCD display 47 on the operation panel 40 also displays, for example, “Master setting direction is opposite. Check the master setting direction. Will be displayed. Upon receiving this message, the user takes out the master roll 10A and resets it so that the front and back sides are correct.
Contrary to the above, when the determination means 28 recognizes / determines that the fluctuation range of the detection voltage is large and is on the porous fiber membrane 13 side, the photosensor 20 is shown as a solid line in FIGS. From the point of being arranged so as to detect the porous fiber membrane 13 surface side, it is comprehensively determined that the front and back of the master 10 are properly set, and the above-described normal plate making / plate feeding operations are executed. It will be.
As described above, all the differences in the detected voltages at the three locations may be compared, or the maximum and minimum differences in the detected voltage differences may be compared.

Next, the case of continuous sampling will be described. In comparing the detection voltage data of the photosensor 20, it is more convenient to convert it into digital data. Therefore, since continuous sampling can be considered as intermittent sampling with a large number of samplings, a detailed description will be given. Omit. Strictly speaking, it is not continuous sampling of the detection voltage but intermittent sampling with a large number of samplings.
If the number of sampling data of the detection voltage of the photosensor 20 is increased, data can be prevented from being missed and the final determination accuracy is improved. However, problems such as the time required for data processing (data processing time) and the place where data can be stored (address space) occur, so it is necessary to select the number of samples and the processing content according to the system.

With reference to FIG. 6, the flow after the detection voltage data sampling of the photosensor 20 will be described. Here, description will be made assuming that detection voltage data is acquired a certain number of times (N times) according to the data sampling content described above.
First, the first detected voltage data is acquired with the processing count i = 0 (zero), and the acquired data is held and stored in the register 26 (steps S1 to S3). Next, the process proceeds to step S4, where the count of the processing number i is increased by 1 (i + 1 → i). Next, the process proceeds to step S5, and if the number of times of processing i is smaller than the set value N times, the process returns to step S2 and is repeated from the acquisition of the detected voltage data.
If the detection voltage data acquisition for the set number of times (N times) is completed, data processing is performed and determination is performed (step S6). Here, the data processing is performed after the set number of times of data acquisition, but the data processing may be performed in parallel with the detection voltage data acquisition.

Here, specifically, the data processing in step S6 means performing the following processing.
(1) Maximum value detection (max value) in acquired data
(2) Minimum value detection (min value) in acquired data
(3) Calculation of maximum value-minimum value (4) Calculation of difference between acquired data (there are many combinations such as previous data and current data, current data and subsequent data)
(5) Integration of acquired data (6) Calculation of average value of acquired data (7) Calculation of number of data above a certain threshold (8) Calculation of number of data below a certain threshold

As described above, in this embodiment, it can be said that the master front / back detection method according to claims 1 to 3 described in the section for solving the problem is used.
The master front / back detection device 23 and the master front / back detection method of the present embodiment are not limited to the front / back detection of the master 10 having the three-layer structure shown in FIG. 5B. For example, a thermoplastic resin film, a Japanese paper fiber, or a synthetic fiber is used. Alternatively, it can also be used to detect the front and back of a normal master having a laminate structure in which a porous support made of a mixture of Japanese paper fiber and synthetic fiber is bonded via an adhesive or the like. The same applies to the embodiments and modified examples described later.
The photosensor 20 needs to be capable of detecting a normal master Japanese paper fiber or the like (porous support) or the porous fiber film 13 (porous support) of the master 10. As explained by way of example, in the current stencil printing apparatus such as “Preport, Satellite” manufactured by Ricoh Co., Ltd., reflection used for detecting the presence of a master on a printing drum (plate cylinder), etc. It has been found that a photosensor of the type can be detected.

As described above, according to the present embodiment, first, what is conventionally detected by two photosensors (reflection type detection means) to detect the front and back of the master 10 is a single ( By using one (one) photosensor 20, the number of photosensors can be reduced to one, the sensor cost is halved, the mechanical layout is halved, and the master 10 can be prevented from being set incorrectly.
According to this embodiment, secondly, when the photosensor 20 is arranged to detect the porous fiber membrane 13 (porous support) side of the master 10, the photosensor 20 is a porous fiber membrane. By making use of the fact that the detection voltage varies greatly at the scanning / detection position by scanning the 13th surface, the determination means 28 determines the difference in the detection voltage from the photosensor 20 (the output signal value). In other words, the front and back of the master 10 is determined based on the variation, but the porous fiber film 13 is outside the master roll 10a (film in-plane winding), and the photo sensor arrangement Considering the mechanical layout, there is an effect that it is easy to layout and design. In addition, since the photo sensor 20 is arranged on the upper side with respect to the master 10, it is difficult to be affected by the adhesion or accumulation of the master powder or dust, that is, the malfunction is less likely to occur. There is also.

Third, according to the present embodiment, when the detection voltage sampling by the photosensors 20 at a plurality of locations of the master 10 is intermittently performed, the number of detection voltage data can be suppressed, and the dedicated hardware configuration is simplified. In addition, there is an effect that the processing time required for the determination of the front and back of the master 10 can be shortened.
In addition, according to the present embodiment, fourthly, when sampling of the detection voltage by the photosensors 20 at a plurality of locations of the master 10 is continuously performed, characteristics of the master 10 (smoothness and porosity of the film 11 surface) The determination accuracy when determining the front and back of the master is improved without missing the fiber unevenness of the fiber membrane 13 surface.

(Modification of the first embodiment)
A modification of the first embodiment will be described with reference to FIG. Compared with the first embodiment, this modification is arranged to scan and detect the porous fiber membrane 13 surface side in the first embodiment as shown by the solid line in FIGS. 1 and 2. In place of the photosensor 20, the photosensor 20 is arranged so as to scan and detect the film 11 surface side as indicated by a broken line in FIG. The main difference is that the determination of the front and back of the master 10 is made based on the small difference in detection voltage (small difference in output signal value). The present modification is the same as the first embodiment except for the differences.

  Therefore, according to this modification, in addition to the same effects as those of the first, third, and fourth of the first embodiment described above, instead of the second effect of the first embodiment described above, The effect of. That is, when the photo sensor 20 is arranged so as to detect the film surface 11 (thermoplastic resin film) surface side, the photo sensor 20 scans the film surface 11 surface, so that the detected voltage is the scanning / detection position. By utilizing the fact that the variation in voltage is small, the determination means 28 uses the small difference in detection voltage from the photosensor 20 (small difference in output signal value), in other words, the variation in detection voltage is small. By determining the front and back of the master 10 from nothing, the voltage fluctuation range is narrowed. In the detection voltage data processing, digitization is performed by the A / D converter 25. However, since the voltage range is narrow, a low bit can be used at the time of the A / D conversion. When the number of bits is reduced (for example, from 8 bits to 6 bits), the circuit (for example, the register 26) in the dedicated H / W 24 can be reduced. If the number of circuits in the dedicated H / W 24 can be reduced, the cost can be reduced.

(Second Embodiment)
With reference to FIG. 7 and FIG. 8, the master kind detection apparatus 32 (it shows with a dashed-dotted line in FIG. 7) which concerns on 2nd Embodiment is demonstrated.
As shown in both drawings, the master type detection device 32 includes a photosensor 30 as color detection means for detecting the coloring of the colored portion 10C indicated by the sand pattern in the drawing of the coloring master 10B as an example of the colored master. The determination unit 36 mainly determines the type of the master 10 based on a detection voltage as an output signal from the photosensor 30.

Compared with the master 10 having the three-layer structure shown in FIG. 5, the coloring master 10 </ b> B used in the present embodiment, for example, can color the porous fiber film 13 in blue and identify the type of master by this color. The only difference is that In other words, the coloring master 10B is the same as the master 10 except for the above-described differences in material configuration. Examples of a method for coloring the porous fiber membrane 13 in blue include dyeing the entire porous fiber membrane 13 by an appropriate dyeing method.
The coloring master 10B is used, for example, to enable discrimination between a non-genuine product (master counterfeit product, etc.) and a genuine product (genuine product) at a stencil printing apparatus or master export destination, This is because it is possible to identify the printing master (master with high durability), or to distinguish between a master manufactured by a company and a master manufactured by another company.

The coloring portion (colored portion) and coloring method of the colored master are not limited to those shown in FIG. 8, but the whole porous resin film 12 is dyed by a specific dyeing method, or the normal master thermoplasticity. Examples include those obtained by dyeing an adhesive used for adhering a resin film to Japanese paper fiber (porous support) or the like, or those obtained by dyeing a thermoplastic resin film by an appropriate dyeing method. A master may be used. Further, when the master is partially colored, for example, a coloring method such as coloring one end portion or one side edge portion of the master with magic ink or attaching a coloring tape may be used.
In order to economically mass-produce a colored master at a uniform concentration, it is preferable to color the master by coloring the whole coloring portion rather than coloring the master partially.

  The plate making apparatus 1 has a master type detection device 32. Here, “the plate making apparatus 1 has the master type detection device 32” means that the A / D converter 25 and the determination means 31, which will be described later as control components of the master type detection device 32, are not necessarily included in the plate making apparatus 1. It is not meant to be arranged, and is meant to be electrically connected and arranged via a signal line or an electric wire to a control board or the like in the apparatus main body 50 arranged outside the plate making apparatus 1, It means that it substantially belongs to the plate making apparatus 1.

  The photo sensor 30 is located at the same position as the photo sensor 20 according to the first embodiment shown in FIGS. 1 and 2, and is arranged so as to detect the color of the colored portion 10C of the coloring master 10B. . The photosensor 30 is electrically connected to the A / D converter 25 via a signal line. The photosensor 30 is a reflective photosensor, and a wavelength of reflected light from a light emitting element made of, for example, an LED having a peak emission wavelength characteristic at a wavelength corresponding to the coloring of the coloring master 10B, and a colored portion 10C of the coloring master 10B. And a light receiving element made of, for example, a phototransistor having a peak sensitivity wavelength characteristic.

The determination unit 31 is configured by including a microcomputer including a CPU, a ROM, a RAM, an I / O interface, and the like. The CPU has a control function in addition to the calculation function. The determination means 31 determines the type of the coloring master 10B from the input detection voltage based on the operation program called from the ROM and related data, and the master feed motor 5, the LCD display 47 of the operation panel 40, and the plate making. It has a function of controlling the thermal head 2 through the control unit 21 as described later.
The ROM of the determination unit 31 stores an operation program and related data for controlling the thermal head 2 via the master feed motor 5, the LCD display unit 47 of the operation panel 40, and the plate making control unit 21, and this operation program. And related data are appropriately called up by the CPU of the judging means 31. The RAM of the determination unit 31 has a function of temporarily storing the calculation result of the CPU.
In the control configuration shown in FIG. 7, the detection voltage transmitted from the photosensor 30 is an analog value as in the first embodiment. Therefore, conversion to a digital value is effective in the influence of noise or the like in post-processing. This is advantageous when the calculation by the judging means 31 is considered.

Next, the operation of the master type detection device 32 will be described.
When a power switch (not shown) for supplying power to each device / unit of the stencil printing apparatus is turned on, power is supplied to the photosensor 30 and the determination means 31 of the master type detection device 32 and the master The feed motor 5 and the like are prepared for power supply and become ready for operation. At this time, if the coloring master 10B is set in the same manner as the master 10 shown in FIGS. 1 and 2, the photosensor 30 performs the color detection operation of the colored portion 10C in the coloring master 10B as follows.

Here, for example, the case where the colored portion 10C of the coloring master 10B shown in FIG. 8 is colored in blue will be described. In the photosensor 20 including the same infrared sensor as the first embodiment (emitting infrared light having a wavelength of 905 nm), the standard white color of the master 10 used in the first embodiment and the blue color of the coloring master 10B are used. When are the same density (brightness), almost the same detection voltage is output, so that a difference (difference) due to coloring cannot be detected.
Illustratively, the white master 10 used in the first embodiment and the photo sensor 20 including the same infrared sensor as the first embodiment (emitting infrared light having a wavelength of 905 nm) The detection voltages in the case of detecting the colored master 10B in which the white master was colored in blue were the same 3V, and no difference occurred. As described above, the photo sensor 20 cannot distinguish between the master 10 and the coloring master 10B.

Therefore, in the photosensor 20 according to the first embodiment including an infrared sensor (for example, emitting infrared light having a wavelength of 905 nm), the density (brightness) is such that there is almost no difference in detection voltage between white and blue. However, it is effective to change to a photosensor 30 that reacts to a wavelength different from that of infrared rays (for example, the emission wavelength of infrared light from 905 nm to the emission of red light from the light emitting device is 630 nm).
Specifically, the photosensor 30 has a light emitting element composed of a red LED having a red wavelength (for example, a wavelength of 630 nm), in other words, a wavelength that reacts with colored blue, in this case, a peak emission wavelength characteristic in red. In addition to the light emitting element, the light receiving element made of a phototransistor having a peak sensitivity wavelength characteristic (for example, a red wavelength of 630 nm) at the wavelength of the reflected light from the colored portion 10C of the coloring master 10B is colored blue. The detection voltage from the photosensor 30 that detects the colored master 10B is lower than the white color and output. In this way, by making the light emitting element a red LED having a peak emission wavelength characteristic in red, it reacts to the density (brightness) of black and white, but also reacts to a specific color, particularly in blue. When the colored master 10B is detected, the detection voltage is lowered and output as compared with the case of the white master 10.
At this time, the detection voltage changes depending on the density (brightness) colored blue. If the blue color is dark, the detection voltage from the photosensor 30 is low, and if the blue color is white, the detection voltage is high. Thus, blue can be detected by sensing the coloring master 10B colored in blue with a red LED light emitting element or the like that has a wavelength sensitivity to red.
Illustratively, the white master 10 used in the first embodiment and the blue color used in the present embodiment by the photosensor 30 including the light emitting element composed of the red LED in the second embodiment. When the white color master 10B was detected, the detected voltage was 3 V, which was the same as that described above, but the blue color master 10B was 1 V, which was a clear difference. Thus, in the photosensor 30, the master 10 and the coloring master 10B could be identified.

Here, for example, the master type when the white master 10 is a non-genuine product and the blue coloring master 10B is a genuine product such as a high image quality master is identified and determined. A high image quality master is one that has excellent punchability and improved print image quality.
For example, when the detection voltage input from the photosensor 30 to the determination means 31 via the A / D converter 25 is 3 (V), the determination means 31 is a photosensor stored in advance in the ROM. Recognize / determine that the white master 10, which is a non-genuine master, is set in the plate-making apparatus 1 by calling the relational data relating to the data table of 30 detection voltages and master types At the same time, the thermal head 2 is stopped from driving via the plate making control unit 21, and at the same time, the rotational driving of the master feed motor 5 is stopped. It is not a genuine product such as a master. Please set a coloring master 10B of a genuine product such as a high-quality master. ”Will be displayed. Upon receiving this message, the user takes out the master roll 10A of the white master 10 and performs operations such as resetting the master roll 10A of the genuine coloring master 10B.
Contrary to the above, when the input detection voltage is 1 (V), the determination means 31 recognizes that the blue coloring master 10B related to a genuine product such as a high image quality master is properly set. Judgment is made and the normal plate making / plate feeding operation described above is executed.

  The stencil printing apparatus is preferably provided with setting means for setting the master type, and the master type information set by the setting means is compared with the detected voltage of the photosensor 30 serving as the detected master type information. However, if the two match, it may be assumed that an optimum master has been set, and the thermal head 2 and the master feed motor 5 are driven to execute plate making. If they do not match, if a warning message is issued on the LCD display unit 47, useless masters and printing paper 62 are not generated, and time loss is eliminated. It is also possible to detect the remaining amount of the master by changing the coloring intensity in one master roll.

  In the above-described operation example, it has been described that only the blue color of the coloring master 10B is recognized / determined. For example, in the plate making apparatus 1 and the stencil printing apparatus illustrated with reference to FIG. If configured, a photo diode including a light emitting element having a peak emission wavelength characteristic at a wavelength corresponding to the coloring of the master and a light receiving element having a peak sensitivity wavelength characteristic at a wavelength of reflected light from the colored portion of the master. As many sensors (color detection means) as the number corresponding to the coloring of each master may be arranged so as to detect the color of each master.

  As described above, according to the present embodiment, the type of master is determined based on the photosensor 30 (color detection means) that detects the coloring of the colored master and the detection voltage (output signal) from the photosensor 30. The photo sensor 30 includes a light emitting element having a peak emission wavelength characteristic at a wavelength corresponding to the coloring of the master, and reflected light from the colored portion of the master. By having a light receiving element having a peak sensitivity wavelength characteristic at the wavelength, in other words, an element having a wavelength corresponding to the coloring color of the master is used, so that the color of the coloring master can be detected. This makes it possible to identify the type of master, thereby reducing set mistakes for different masters and making optimal settings for that master. By becoming way, machine performance is improved.

(Third embodiment)
With reference to FIG. 8 and FIG. 9, a master front / back surface detection device 37 (indicated by a one-dot chain line in FIG. 9) according to the third embodiment will be described. It should be noted that the master front / back surface detection device 37 should also be referred to as a master front / back surface / type detection device because it can detect the front and back surfaces of the colored master and the type of the colored master.
The master front / back surface detection device 37 of the third embodiment is unique to the master front / back surface detection device 23 of the first embodiment shown in FIG. 4 and the master type detection device 32 of the second embodiment shown in FIG. This corresponds to a control component added with a configuration / function. That is, the master front / back surface detection device 37 of the present embodiment uses the same photosensor 30 as shown in FIG. 7 instead of the photosensor 20 as compared with the master front / back surface detection device 23 shown in FIG. The main difference is that a determination unit 36 is used instead of the unit 28.

That is, the master front / back detection device 37 scans the front or back surface of the coloring master 10B and detects the color together with the front and back, and the moving means for moving the coloring master 10B relative to the photosensor 30. The master feed motor 5 and the platen roller 3 that constitute the image data, and the output signal relating to the front or back surface of the coloring master 10B detected by the photosensor 30 and the type of master, that is, the detection voltage from the photosensor 30 are input. The dedicated H / W 24 for signal processing and the operation of the thermal head 2 are controlled via the master feed motor 5, the LCD display 47 of the operation panel 40 and the plate making control unit 21, and input from the dedicated H / W 24. Judging the front and back of the coloring master 10B from the difference in detected voltage and the type of master from the detected voltage Is mainly composed of determination means 36 for determining.
The plate making apparatus 1 has a master front / back detection device 37. Here, “the plate making apparatus 1 has the master front / back detection device 37” means that the dedicated H / W (dedicated hardware) 24 and the determination means 36, which are control components of the master front / back detection device 37, which will be described later, are not necessarily plate making. It does not mean that it is arranged in the apparatus 1, and includes being electrically connected and arranged via a signal line or an electric wire to a control board or the like in the apparatus main body 50 arranged outside the plate making apparatus 1. This means that it belongs to the plate making apparatus 1 substantially.

The photosensor 30 is a reflection type detection unit, and is the same as the color detection unit of the second embodiment. The judging means 36 includes a microcomputer including a CPU, ROM, RAM, I / O interface and the like. The CPU has a control function in addition to the calculation function. The determining means 36 determines the front and back of the coloring master 10B and the type of the master from the input detection voltage and the difference between them based on the operation program called from the ROM and related data, and the master feed motor 5, the operation panel The thermal head 2 has a function of controlling the thermal head 2 as will be described later via the 40 LCD display units 47 and the plate making control unit 21.
In addition, the determination unit 36 uses the dedicated H / W 24 to detect a difference between detection voltages at a plurality of locations detected by scanning the front surface or the back surface of the coloring master 10 </ b> B with the photosensor 30. Is obtained by sampling (extracting) intermittently (discretely). The determination means 36 is not limited to the function obtained by sampling (extracting) intermittently, but continuously detects the difference between the detection voltages at the plurality of locations and the detection voltage from the photosensor 30 via the dedicated H / W 24. A function obtained by sampling may be provided.
The ROM of the determination means 36 stores an operation program and related data for controlling the thermal head 2 via the master feed motor 5, the dedicated H / W 24, the LCD display section 47 of the operation panel 40 and the plate making control section 21. The operation program and related data are appropriately called up by the CPU of the judging means 36. The RAM of the determination unit 36 has a function of temporarily storing the calculation result of the CPU.

Next, the operation of the master front / back surface detection device 37 will be described with reference to FIGS. 1 to 6.
When a power switch (not shown) for supplying power to each device / part of the stencil printing apparatus is turned on, power is supplied to the photosensor 30, the dedicated H / W 24, and the judging means 36 of the master front / back surface detection device 37. At the same time, preparations for supplying power to the above-described devices and units including the plate making control unit 21, the thermal head 2, and the master feed motor 5 are made, and the apparatus becomes operable. At this time, if the coloring master 10B is set in the same manner as the master 10 shown in FIGS. 1 and 2, the photo sensor 30 detects the color of the colored portion 10C in the coloring master 10B as in the second embodiment. To be done.
The platen roller 3 and the tension roller pair 4a are activated when the master feed motor 5 is started by using a start signal generated by pressing the plate making start key 41 during the above-described plate discharging and plate making operations or after the master roll 10A is replaced. , 4b are rotated. As a result, the coloring master 10B is pulled out from the master roll 10A and conveyed downstream in the sub-scanning direction Y.

At this time, when the porous fiber membrane 13 surface of the colored master 10B is scanned by the photo sensor 30 arranged to scan and detect the colored porous fiber membrane 13 surface side as shown in FIG. The scan detection voltage waveform from the photosensor 30 is output as in the first embodiment. Further, the scan detection voltage waveform from the photosensor 30 when the film 11 surface of the coloring master 10B is scanned is output in the same manner as in the first embodiment.
As in the first embodiment, when the determination means 36 recognizes and determines that the film 11 is on the surface side of the film 11 because the fluctuation range (variation width) is small, the photosensor 30 is porous as shown in FIG. From the point where it is arranged so as to detect the surface side of the conductive fiber membrane 13, it is comprehensively determined that the coloring master 10 </ b> B is reversely set in the opposite direction and is not set properly, and through the plate making control unit 21. At the same time as the thermal head 2 is stopped, the rotation of the master feed motor 5 is stopped, and the LCD display 47 on the operation panel 40 also displays, for example, “Master setting direction is opposite. Check the master setting direction. Will be displayed. Upon receiving this message, the user takes out the master roll 10A and resets it so that the front and back sides are correct.
Contrary to the above, when the judging means 36 recognizes and judges that the fluctuation range (variation width) is large and is on the side of the porous fiber membrane 13, the photosensor 30 is shown by a solid line in FIGS. Thus, it is comprehensively determined that the front and back of the coloring master 10B are properly set from the point of being arranged so as to detect the surface side of the porous fiber membrane 13 as described above, and the normal plate making / plate feeding operation described above is performed. Will be executed.

In the present embodiment, since the photosensor 30 scans a master such as the white master 10 or the coloring master 10B to detect coloring, the detection voltage input from the photosensor 30 to the determination unit 36 via the dedicated H / W 24. May be processed by the following determination formula.
That is, when it is desired to extract the magnitude of the detection voltage variation in consideration of the color density, the following four determination formulas can be applied.
(1) Maximum value (max value) ≧ a certain threshold value (2) Minimum value (min value) ≦ a certain threshold value (3) Maximum value−minimum value ≧ a certain threshold value In (3), the fluctuation range of the detected voltage is known. If a threshold value is set and a condition that is equal to or greater than the threshold value is set, it can be determined whether the detected voltage fluctuation is large.
(4) Difference between before and after data ≧ a certain threshold value When a difference between certain detection voltage data is obtained, if the difference is greater than a certain set threshold value, it can be determined that the fluctuation range is large.
When it is desired to extract the small variation in the detection voltage in consideration of the coloring density, the above may be reversed. The symbol of the determination formula may be ≧ or>.

Here, for example, as in the second embodiment, the type of master is identified and determined when the white master 10 is a non-genuine product and the blue coloring master 10B is a genuine product such as a high image quality master. And The determination means 36 calls the relational data related to the data table of the detection voltage and the master type related to the determination formula of the photosensor 30 stored in advance in the ROM, and compares and compares it with the determination formula. If not satisfied, it is recognized and judged that the white master 10 which is a non-genuine master is set in the plate making apparatus 1, and the thermal feed 2 is stopped through the plate making control unit 21 and at the same time, the master feed motor 5 At the same time, on the LCD display 47 of the operation panel 40, for example, “Master type is not a genuine product such as a high image quality master. A genuine color master 10B such as a high image quality master is set. Please display a warning / message saying "Please." Upon receiving this message, the user takes out the master roll 10A of the white master 10 and performs operations such as resetting the master roll 10A of the genuine coloring master 10B.
Contrary to the above, when the determination formula is satisfied, it is recognized and judged that the blue coloring master 10B relating to the genuine product such as the high image quality master is properly set, and the normal plate making / plate feeding operation described above is performed. Will be executed.
Not only the coloring master 10B, but corresponding to the above-described colored master example, the photo sensor 30 is arranged so that the color can be detected, and the color of the colored master is detected by the control configuration shown in FIG. Of course, it is possible to detect the type of the master by identifying.

According to the present embodiment, the same effects as those of the first and second embodiments can be obtained only by arranging the single photosensor 30 using the coloring master 10B.
In the present embodiment, the detection voltage input by the determination means 36 is processed by the above determination formula using the dedicated H / W 24. However, the present invention is not limited to this, and the control configuration shown in FIG. 7 in the second embodiment is used. A simple determination / judgment such as the determination unit 31 may be used.

A printing apparatus to which the master front / back detection method, master front / back detection apparatus, and master type detection apparatus of the present invention can be applied includes the printing drum 101 shown in FIG. 1 and is limited to a thermosensitive digital stencil printing apparatus integrated with plate-making printing. First, for example, if it has a plate making apparatus having a plate making means for making a master in accordance with image information and can wind a pre-made master on the outer peripheral surface of the printing drum 101, for example, printing exclusively for A4 plate Needless to say, the present invention can be applied to various printing apparatuses such as a stencil printing apparatus, a multicolor stencil printing apparatus, or a double-sided stencil printing apparatus having a drum.
For example, as disclosed in Japanese Patent Application Laid-Open No. 8-118774, a two-drum opposed transfer cylinder interposed type one-pass simultaneous double-sided printing drum and printing apparatus, and Japanese Patent Application Laid-Open No. 9-95033 are disclosed. Printing drum and printing apparatus of the one-drum division printing simultaneous reversal type duplex printing system, or printing drum and printing of the one-drum division printing transfer cylinder 1-pass duplex printing system as disclosed in JP-A-10-129100 It is also applicable to the device.
That is, the printing apparatus to which the present invention can be applied only needs to have the configuration of the eleventh aspect described in the section for solving the problem. At this time, examples of the pressing unit that indirectly presses the printing medium on the master plate on the printing drum include the transfer cylinder of the above example.

  As described above, the present invention has been described with respect to specific embodiments and the like, but the technical scope disclosed by the present invention is not limited to those exemplified in the above-described embodiments and the like. It will be apparent to those skilled in the art that various embodiments, modifications, and examples can be configured within the scope of the present invention in accordance with the necessity and application.

1 is a simplified front view of an entire stencil printing apparatus showing a first embodiment of the present invention. It is an enlarged front view of the principal part of the plate-making apparatus of FIG. It is a top view of the principal part of an operation panel. It is a block diagram which shows the control structure around the master front and back detection apparatus in 1st Embodiment. (A) is a detection voltage waveform when a porous fiber membrane surface is scanned by a photosensor, (b) is a cross-sectional configuration of a master having a three-layer structure, and (c) is a film surface scanned by a photosensor. It is a figure which shows the detection voltage waveform at the time, respectively. It is a flowchart which shows the data processing content after detection voltage data sampling by a photosensor. It is a block diagram which shows the control structure around the master kind detection apparatus in 2nd Embodiment. It is a figure which shows the cross-sectional structure of the coloring master in 2nd Embodiment, and arrangement | positioning of the photosensor which detects the color. It is a block diagram which shows the control structure around the master front and back detection apparatus in 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plate making apparatus 2 Thermal head (plate making means)
10 Master 10A Master roll 10B Colored master (colored master)
10C Colored part 11 Thermoplastic resin film 12 Porous resin film 13 Porous fiber film (porous support)
20 Photosensor (Reflection type detection means)
23, 37 Master Front / Back Detection Device 24 Dedicated H / W
28, 31, 36 Judgment means 30 Photosensor (color detection means, reflection type detection means)
32 Master type detection device 62 Printing paper (printed medium)
40 Operation panel (operation unit)
101 Printing drum 103 Press roller Y Sub-scanning direction

Claims (11)

  A single reflection type detection means is disposed on the front side or the back side of the master provided with either the thermoplastic resin film or the porous support on the front side or the back side, and the master and the reflection type detection means By moving either one of them relatively, the surface or the back surface of the master is scanned by the reflection type detection means, and the output signal values from the reflection type detection means at a plurality of locations on the scanned surface or the back surface of the master are scanned. A master front / back detection method characterized in that the front / back of a master is determined from a difference.   When the reflection type detection means is arranged to detect the thermoplastic resin film surface side, the front and back of the master is judged from the small difference in the output signal value from the reflection type detection means. The master front and back detection method according to claim 1.   When the reflection type detection means is arranged to detect the porous support surface side, the front and back sides of the master are determined from the difference in output signal values from the reflection type detection means. Item 2. The master front / back detection method according to Item 1. A single reflection type detecting means arranged on the front side or the back side of the master provided with either the thermoplastic resin film or the porous support on the front side or the back side;
Moving means for moving one of the master and the reflection type detecting means with respect to the other;
Judgment means for judging the front and back of the master from the difference of output signal values from the reflection type detection means at a plurality of locations on the front or back surface of the master scanned by the reflection type detection means via the movement means;
A master front / back surface detection device comprising:   When the reflection type detection unit is arranged to detect the thermoplastic resin film surface side, the determination unit determines the front and back of the master from the small difference in the output signal value from the reflection type detection unit. The master front / back detection apparatus according to claim 4, wherein   When the reflective detection means is arranged to detect the porous support surface side, the determination means determines the front and back of the master from the large difference in the output signal values from the reflective detection means. The master front / back surface detection apparatus according to claim 4.   7. The determination unit according to claim 4, wherein the determination unit obtains the difference between the output signal values at the plurality of locations by intermittently sampling the output signal value from the reflection type detection unit. The master front / back detection device described.   7. The determination unit according to claim 4, wherein the determination unit obtains the difference between the output signal values at the plurality of locations by continuously sampling the output signal value from the reflection type detection unit. The master front / back detection device described. The reflection type detection means includes a light emitting element having a peak emission wavelength characteristic at a wavelength corresponding to the coloring of the colored master and a light receiving element having a peak sensitivity wavelength characteristic at a wavelength of reflected light from the colored portion of the master, Also has a function to detect the coloring of the colored master,
The master front / back detection apparatus according to claim 4, wherein the determination unit also determines a master type based on an output signal from the reflection type detection unit. A master type detection device comprising: color detection means for detecting coloring of a colored master; and determination means for determining the type of master based on an output signal from the color detection means,
The color detection unit includes a light emitting element having a peak emission wavelength characteristic at a wavelength corresponding to coloring of the master, and a light receiving element having a peak sensitivity wavelength characteristic at a wavelength of reflected light from a colored portion of the master. Master type detection device.   A plate making apparatus comprising the master front / back detection device according to any one of claims 4 to 9 or the master type detection device according to claim 10, and comprising plate making means for making a master according to image information, and plate making A printing apparatus comprising: a printing drum on which an already-printed master is wound around an outer peripheral surface, and printing is performed by directly or indirectly pressing a printing medium on the master-printed master on the printing drum.

Images