JPH1124327A - Master length controlling method and controller for digital plate making machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a master length controlling method for a digital plate making machine capable of obtaining a master sheet having exact length required in the plate drum of a printing machine without being influenced by the inertial weight of a photosensitive sheet roll or the individual difference of the device. SOLUTION: In this method, an edge detector ES capable of detecting the leading and the trailing edges of the master sheet X in a state where it faces to the peripheral surface of a feeding roller 6 just before a scanning position by a laser scanning unit 10 is arranged to measure physical quantity equivalent to the rotational angle of the roller 6 from detecting the leading edge till detecting the trailing edge by the detector ES. The actual length of the passing master sheet X is calculated from the physical quantity and the revolving speed of a take-in part roller 31 is corrected based on the result of the previous arithmetic operation of the length of the master sheet X when the next master sheet X is fed out and cut.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital plate making machine for producing a printing original using read image information, and more particularly, to a master sheet obtained by cutting a sheet of a photosensitive sheet roll. The present invention relates to a master length control method and device for controlling.

[0002]

2. Description of the Related Art As is well known, in a plate making machine for producing a printing original plate, an original on which a required image is recorded is placed on a platen, and the image of the original is optically placed on the surface of a master sheet. Exposure is performed, and the master sheet is developed with a toner to form a printing master.

However, with the development of computer graphic technology in recent years, there has been an increasing demand for producing a printing plate using a plate making machine using image information handled by a computer. In other words, the image information handled by recent digital computers has been getting sufficient image quality as a precise print image in both pixel density and gradation, and it is possible to directly create a printing master using the image information. Contains gender.

[0004]

When planning a digital plate making machine used for such purposes, the length of a master sheet on which image information is printed can be easily specified by a digital computer. Rather than preparing a pre-cut master sheet
It is much more advantageous to prepare a master sheet by cutting a sheet drawn from the photosensitive sheet roll into a required length each time a photosensitive sheet roll is prepared and used.

However, when a sheet is taken out of such a photosensitive sheet roll by an intake roller or the like and cut by a cutter to obtain a master sheet of a required length, the difference in solids of a plate making machine and the inertia of the photosensitive sheet roll are required. Due to the weight, there is a problem that even if the number of rotations of the intake roller is the same, master sheets having different lengths are obtained. That is, since there is a "slip" movement with a difference between the sheet taken out of the photosensitive sheet roll and the take-in section roller, it can be obtained only by rotating the take-up section roller by a predetermined number of rotations. The length of the master sheet is different.

The inertial weight of the photosensitive sheet roll is:
Since the load inertia of the inertial sheet roll with respect to the intake roller always changes because it differs each time depending on the winding diameter, winding width, and type of web base, the above-mentioned “slip” is naturally used.
Exercise will also change.

[0007] On the other hand, in a printing machine using a manufactured master sheet, a master sheet having a strict length corresponding to the outer diameter of a mounted plate cylinder is required. Front or rear grip margins are required before and after the master sheet.

Further, considering the reality of a digital plate making machine for processing image information handled by a digital computer, it can be seen from the current peripheral technology that such a digital plate making machine adjusts the master sheet in the sub-scanning direction. The structure that supplies the image information to the peripheral surface of the feed roller driven at high speed and exposes the image information from the laser scanning unit to the photosensitive surface of the master sheet in the main scanning manner is the most worth considering.

A first object of the present invention is to provide a printing master by reading various image information handled by a digital computer or the like in view of the current state of the conventional plate making machine as described above. The master sheet of the required length can be cut from the sheet roll each time, and the master sheet of the exact length required by the plate cylinder of the printing press is not affected by the inertial weight of the photosensitive sheet roll and the individual differences of the equipment. To achieve a master length control method for a digital plate making machine that can obtain the following.

A second object of the present invention is to provide a master length control device for a digital plate making machine for realizing a master length controlling method for a digital plate making machine which achieves the first object.

[0011]

In order to achieve the first object, according to the present invention, a photosensitive sheet roll of a sheet roll supply section is fed out and cut by a loading section roller to form a master sheet. In a digital plate making machine that supplies image information from a laser scanning unit in a main scanning direction to a photosensitive surface of a master sheet on a photosensitive surface of a master roller, the image is supplied to a peripheral surface of a feed roller that is driven to rotate in the sub-scanning direction. An edge detector capable of detecting the front and rear edges of the master sheet facing the peripheral surface of the feed roller is disposed, and corresponds to the rotation angle of the feed roller between the front edge detection and the rear edge detection by the edge detector. Measure the physical quantity, calculate the actual length of the master sheet passed from the physical quantity, and calculate the next master sheet Proposes a master-length control method for a digital plate making machine to be modified by the length of the calculation result of the previous master sheet the rotational speed of the join the club roller taken when feeding cut.

In the following description of embodiments of the present invention, the "physical quantity" is exemplified by a scan pulse for each scan obtained by synchronous rotation of a polygon mirror of a laser scanning unit. The “physical quantity” may be a known drive pulse used for rotationally driving the feed roller or a clock pulse used for synchronously driving each part of the digital plate making machine.

Further, according to the present invention, the above-mentioned second object is to provide a master sheet by feeding out and cutting a photosensitive sheet roll of a sheet roll supply section by an input section roller, and the master sheet is moved in the sub-scanning direction. In a digital plate making machine, in which image information is main-scanned from a laser scanning unit onto a photosensitive surface of a master sheet, the feed roller is supplied immediately before a scanning position by the laser scanning unit. An edge detector arranged facing the peripheral surface of the master sheet, information on the front and rear edges of the master sheet from the edge detector and a physical quantity corresponding to the rotation angle of the feed roller are input, and after the edge detection of the front edge of the passed master sheet. Control for calculating the actual length of the master sheet from the physical quantity until the edge detection And a location, the control device is accomplished by the following master sheet master length control apparatus for digital plate making machine to be modified by the calculation result of the length of the previous master sheet the rotational speed of the intake portion roller during feeding cleavage.

In the following description of a preferred embodiment of the present invention, 1) a scanning pulse sensor for the physical quantity which outputs a scanning pulse for each scanning obtained by synchronous rotation of a polygon mirror of the laser scanning unit; An up-counter for counting the scanning pulses from the detection of the leading edge to the detection of the trailing edge of the master sheet passed by the command of the control device, and the exposure information of the master sheet being processed is registered and the calculation result by the control device And a comparison register that updates the rotation speed data of the take-in roller with respect to the length of the master sheet in the exposure information registered in the exposure information, and 2) the rotation speed of the take-in roller is the same as that of the take-in roller. A configuration that is monitored by an encoder that is rotated in synchronization with the encoder will be described.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a digital plate making machine DS of the present invention used for a communication network system,
Image information of the plurality of local computers RC coupled to W is supplied to the host computer HC via the same communication network NW.

The host computer HC capable of controlling the digital plate making machine DS calculates the sent image information, that is, the position and size of the image and the length of the master sheet X to be used, and performs digital plate making via the server SV. Machine DS. That is, the server SV exchanges image information with the digital plate-making machine DS via the data bus DB, and transmits the image information together with the synchronization signal to the laser scanning unit 10 of the digital plate-making machine DS, which will be described in detail later, at a necessary timing. Send out. Note that the digital plate making machine DS according to the present invention includes a side door 4 that can be opened with the front door 2 and the lower hinge 3 of the left hinge located on the front of the body frame 1 as fulcrums. By opening the photosensitive sheet roll SR, the photosensitive sheet roll SR can be loaded.

FIG. 2 shows the entire digital plate making machine DS according to the present invention. A sheet roll supply section 20 for drawing a sheet from the photosensitive sheet roll SR and cutting it to a required length is arranged at the lower right of the machine frame 1. The cut master sheet X waits in a master supply unit 40 provided above the sheet roll supply unit 20 and is then charged on the surface by a charger 5 and strictly controlled by a stepping motor (not shown). Is supplied to the peripheral surface of the feed roller 6 for performing the following.

A laser scanning unit 10 to which image information is sent from the server SV is provided above the body frame 1. Inside the laser scanning unit 10, a polygon mirror 11 rotated by a synchronization signal is provided. , A condensing lens 12 and a reflection mirror 13, and a feed roller 6 is disposed immediately below the laser scanning unit 10. The laser beam from the reflection mirror 13 is scanned by a plurality of pressing rollers 7 on the surface of the master sheet X which is brought into close contact with the peripheral surface of the feed roller 6. As shown in FIG. 11, the polygon mirror 11 and the feed roller 6 of the laser scanning unit 10 are provided with a control device CPU described later.
A clock signal for synchronization is given from the frequency divider in accordance with the speed setting in the step (1), and the polygon mirror 11 and the feed roller 6 rotate in synchronization with each other. A scanning pulse sensor PS ₃ for detecting scanning is provided,
From the scanning pulse sensor PS ₃ to the polygon mirror 11
The scan pulse for each scan is counted by the up counter UPC. In other words, by counting the number of scanning pulses, it is possible to know the rotation amount of the feed roller 6 whose speed has been adjusted, or in other words, the length of the master sheet X that is moved in close contact with the peripheral surface of the feed roller 6. The master sheet X, on the surface of which the image information has been made into a latent image, is conveyed to the developing unit 60 adjacent to the left side of the feed roller 6, where the image information is developed by the developing unit 60 and then sent to the fixing unit 90. The fixing unit 90 heats and fixes the toner image.
The paper is collected by the paper discharge tray 9 by the function of the paper discharge roller 8 located on the left side of the paper tray.

FIG. 3 shows the details of the above-mentioned sheet roll supply section 20 and master supply section 40. The sheet roll supply section 20 includes a tiltable hanger 21 on which a photosensitive sheet roll SR can be mounted, and a body frame. The tilting hanger 21 suspended by the support shaft 22 with respect to 1 has a jaw portion 21a on which the center rod 23 of the photosensitive sheet roll SR is hung, and when the tilting hanger 21 is at the position shown by the two-dot chain line, Both ends of the center bar 23 passing through the center of the photosensitive sheet roll SR can be hung on the jaw portion 21a. Also,
The bottom wall 1a of the body frame 1 and the tilt hanger 21
A gas stay 24 for applying a lift to the heavy tilt hanger 21 is provided between the lower bracket 25 and the dead center connecting the lower bracket 25 and the support shaft 22. A counterclockwise rotational moment about the center 22 is applied to the tilt hanger 21 to maintain the heavy tilt hanger 21 at the position indicated by the two-dot chain line.

A link arm 26 is provided between the intermediate portion of the side door 4 and the intermediate portion of the tilt hanger 21, and the link arm 26 is connected to the support shaft 22 when the side door 4 is opened. The tilt hanger 21 is rotated about. In addition, the middle part of the side door 4 and the body frame 1
An extensible door arm 27 is fixed between the right and left sides of the door arm by mounting brackets 28 and 29.
Determines the maximum opening angle of the side door 4 when the side door 4 is released.

The sheet roll supply unit 20 includes an intake roller 31, an intake guide 32, a cutter 33 for cutting the sheet drawn from the photosensitive sheet roll SR, and a master supply of the sheet. A relay roller 34 for shifting to the section 40, a transitional mylar sheet 35, and the amount of rotation of the intake section roller 31 is strictly monitored by the rotation of the attached encoder 36;
The cutter 33 cuts the sheet according to a command signal when a sheet of a required length is pulled out by the intake roller 31. When the tilt hanger 21 is at the position shown by the solid line in FIG. 3, the distal end of the elastic transition portion mylar sheet 35 whose base is fixed to the tilt hanger 21 is pressed against the surface of the standby guide plate 41 of the master supply unit 40. Because
The master sheet X fed from the relay roller 34 is
The guide is smoothly guided on the standby guide plate 41. Since the relay roller 34 described above is rotated for a certain period of time in accordance with the support of the server SV, the long master sheet X stands by while being bent on the surface of the standby guide plate 41.

The master supply section 40 has a standby guide plate 41 extending obliquely upward toward the charger 5, and can press the intermediate portion of the standby guide plate 41 against the first transport roller 42 as necessary. A holding roller 43 is provided. The holding roller 43 operated by the electromagnetic solenoid 44 sandwiches the middle portion in the length direction of the master sheet X when the widthwise edge of the front end of the master sheet X is aligned by the front end alignment unit 45 described later. Since the master sheet X is pressed against the first transport roller 42 in this state, the master sheet X can stand by on the surface of the standby guide plate 41 while maintaining this alignment state.

FIGS. 4 and 5 show the standby guide plate 41 described above.
3 shows the details of a leading end alignment unit 45 provided at the upper portion of the standby guide plate 41. The leading end alignment unit 45 has a rotatable alignment shaft 46 extending in the width direction of the standby guide plate 41.
6 is controlled in rotation by an aligning actuator 47 constituted by an electromagnetic solenoid. That is, a pair of aligning pieces 48 facing in the width direction of the standby guide plate 41 are fixed to an intermediate portion of the aligning shaft 46, and these aligning pieces 48 pass through the cutout holes 41 a formed in the standby guide plate 41. Can be interposed in the path of the master sheet X. Further, an urging spring 52 for giving one-way rotation to the aligning shaft 46 and an operating rod 47a of an aligning actuator 47 are engaged with the rotating disk 51 at the shaft end of the aligning shaft 46. By exciting the aligning actuator 47, the aligning shaft 46 can be forcibly rotated against the force of the biasing spring 52.

Since the leading end aligning unit 45 has such a structure, when the master sheet X moves along the standby guide plate 41, the aligning piece 48 is temporarily inserted into the notch hole 41a by the excitation of the aligning actuator 47. Even if the leading edge of the master sheet X is inclined as shown in the figure due to friction or the like between the standby guide plate 41 and the like, the leading edge of the master sheet X is still ,
The state is adjusted to be exactly perpendicular to the moving direction, and the inclination of the latent image with respect to the master sheet X is prevented.
That is, when the leading edge of the master sheet X comes into contact with each of the alignment pieces 48, the tilted inclination of the master sheet X is absorbed by the deflection of the master sheet X on the standby guide plate 41, and the absorbed state is the same as that described above. The holding roller 43 is kept in a holding state by pressure contact between the conveyance roller 42 and the holding roller 43.

On the other hand, at the exit of the standby guide plate 41,
Second movement of the master sheet X toward the charger 5
A transport roller 53 is disposed, and a driven roller 55 operated by a roller actuator 54 composed of an electromagnetic solenoid can be in rolling contact with the second transport roller 53. This roller actuator 54
Since the master sheet X fed by the second transport roller 53 is demagnetized after being taken up by the feed roller 6 regulated by the synchronization signal, the master sheet X bent on the standby guide plate 41 is While returning to the shape, the sheet advances at a constant speed by the feed roller 6, and during this time, the image information is formed into a latent image on the surface of the master sheet X.

FIG. 6 shows the details of the developing section 60 following the feed roller 6. The developing section 60 has a master sheet on which image information is converted into a latent image via a transition section guide plate 61 and a transition section roller 62. X is supplied. That is, the developing unit 60 includes an inlet roller 63A that is arranged in the moving direction of the master sheet X, a spray nozzle 63 that sprays a developing solution on the surface of the master sheet X, and squeezes the excess developing solution attached to the master sheet X. A pair of squeezing rollers 64
A, 64B are provided, and a scraping blade 65 for scraping the developer adhered to the peripheral surface of one of the squeezing rollers 64A, 64B is contacted as necessary.

FIG. 7 shows the details of the scraping blade 65 and its operating mechanism, and shows the above-mentioned squeezing rollers 64A and 64B.
Are dropped into mounting grooves 66 formed in the upper wall 1b of the body frame 1. A blade actuator 67 for operating the scraping blade 65 is configured by an electromagnetic solenoid,
The base of a tilting rod 69 is pin-connected to the distal end of an operating rod 67a of the blade actuator 67 by a connecting pin 68, and between the distal end of the tilting rod 69 and the anchor pin 71 of the upper wall 1b. , A return spring 72 consisting of a tension spring is engaged. A blade support member 73 for supporting the scraping blade 65 is provided at an intermediate portion of the tilt rod 69.
Are supported by a driven pin 74, and the driven pin 74 is located in a “U” -shaped cam groove 75 formed in the upper wall portion 1b.

Since the operating mechanism of the scraping blade 65 has such a structure, in the demagnetized state of the blade actuator 67, the tilting rod 69 is pulled leftward by the return spring 72, so that the blade supporting member 73 and The scraping blade 65 is at the position shown by the solid line, and the tip of the scraping blade 65 is in a state of being separated from the peripheral surface of the squeezing roller 64A. When the developing unit 60 develops the master sheet X, the blade actuator 67 is temporarily excited, so that the operating rod 67 a and the tilt rod 69 are returned by the return spring 7.
2 is moved rightward against the force of
Then, the blade supporting member 73 is slightly rotated to the position shown by the one-dot chain line, and the tip of the scraping blade 65 is brought into contact with the peripheral surface of the squeezing roller 64A, and the surplus developer on the peripheral surface is written off. Then, in order to clean the dirty aperture rollers 64A and 64B, the aperture rollers 64A and 64B
To remove the finger hook 7 in the middle of the blade support member 73.
It is only necessary to hang a fingertip on 3a and lift it upward. That is, when the blade support member 73 is lifted upward, the driven pin 74 moves downward in the cam groove 75, so that the blade support member 73 and the scraping blade 65 are inverted as shown by a two-dot chain line, Is opened above. As a result, the scraping blade 65 and the blade supporting member 73 do not obstruct the work, so that the squeezing rollers 64A and 64B can be easily taken out from the mounting groove 66.
Of course, to return the squeeze rollers 64A and 64B after cleaning,
Maintenance can be easily performed simply by re-attaching the squeezing rollers 64A and 64B in the mounting groove 66 and tilting the blade support member 73 in the state shown by the two-dot chain line clockwise.

Returning to FIG. 6, immediately below the inlet roller 63A, the spray nozzle 63, and the squeeze rollers 64A and 64B, a developer vat 76 for collecting the developing solution flowing down is located. The collected developer is collected in a developer tank 77 located below the developer vat 76. A pump table 82 on which a developer pump 79 and a toner liquid pump 81 are mounted is located immediately below a mount 78 on which the developer tank 77 is provided.
A bottle stand 83 on which a developer bottle EB, a toner bottle TB, and a collected bottle RB can be installed at the lower part of the machine facing
Is provided.

The developer pump 79 and the toner pump 81
And the relationship between the developer bottle EB, the toner bottle TB, and the collection bottle RB.
The two suction ports 79a and 79b are respectively connected to a circulation line 83A controlled by a liquid level gauge not shown and a developer supply line 84 from the developer bottle EB, and a discharge port of the developer pump 79. Is connected to the spray nozzle 63 described above. Further, since the recovery pipe 85 connected to the bottom of the developer tank 77 has an opening / closing cock 86 at an intermediate portion, the opening / closing cock 86 is opened as needed, so that the developer tank is placed in the recovery liquid bottle RB. 77 can be recovered.

The toner liquid pump 81 is driven under the control of a densitometer (not shown).
1a is connected to a toner liquid bottle TB via a toner line 87, and its discharge port is connected to a toner supply line 88.
Through the developer tank 77. Therefore, the developer tank 77 is driven by the driving of the toner liquid pump 81.
The concentration of the developer therein is always kept substantially constant.

FIGS. 7 and 8 show details of the fixing unit 90.
The fixing unit 90 includes a fixing device housing that extends in the width direction of the master sheet X to be passed, and the identification dressing housing includes an upper housing 91A and a lower housing 91B positioned above and below the passing master sheet X. I have. As can be understood from FIG. 8, both ends of the fuser housing inside the upper wall 1b of the body frame 1 are provided with fan motors 92 for taking in the internal air from the position facing the corresponding upper wall 1b. A ceramic heater 93 capable of heating the discharged internal air and a honeycomb rectifying plate 94 for rectifying the heated internal air are disposed on the discharge side, that is, on the inner side of the casing 92a of the fan motor 92, respectively. You. Further, the end plate 91C of the fixing device housing has ventilation holes 94 through which a part of the heated air inside the fixing device housing is diverted to the upper wall 1b side.
95 is provided, and the drying of the master sheet X in cold weather is promoted by the partial circulation of the heated air through the ventilation holes 94 and 95.

Since the fixing section 90 has such a structure, as shown by a broken line in FIG. 8, heated air is blown into the interior of the fixing device housing, and the master sheet X passed by the heated air is dried. Thus, the toner image on the surface of the master sheet X is fixed. In this case, the inside of the fixing device housing is sucked into the inside of the fixing device housing from the vicinity of the upper wall portion 1b of the body frame 1 by the rotation of the fan motor 92, but the ventilation holes 94 and 95 are formed in the end plate 91C of the fixing device housing. Because of the formation, a part of the air heated by the ceramic heater 93 is supplied to the air holes 9.
4, 95, and the air blown out from the ventilation holes 94, 95 is mixed with the suction air. Therefore, even at the time of start-up or cold when the temperature of the air inside the apparatus is low, the temperature of the heated air in the fixing device housing can be increased and the master sheet X can be sufficiently dried.

FIG. 9 shows an edge detector ES provided to face the peripheral surface of the feed roller 6 immediately before the laser beam scanning position of the laser scanning unit 10. A plurality of pressing rollers are provided on the peripheral surface of the large-diameter feed roller 6. Since 7 is transferred,
The master sheet X supplied to the position of the feed roller 6 is supplied to the peripheral surface of the feed roller 6 with its photosensitive surface facing upward, and is “slid” against the feed roller 6.
Is moved in the sub-scanning direction in a state where there is no image. On the peripheral surface of the feed roller 6, a laser beam scanned by the polygon mirror 11 in the main scanning direction perpendicular to the paper surface is standardized, and image information applied to the laser beam is applied to the photosensitive sheet of the master sheet X. Printed on the side. In the case of the illustrated embodiment,
A black paint in a so-called “glossy” state is baked on the peripheral surface of the feed roller 6, and the leading edge and the trailing edge of the master sheet X passing through the mounting member of the device fixing portion located immediately before the laser beam. Is supported by an edge detector ES capable of detecting the

The illustrated edge detector ES is a so-called “reflection type” photocoupler, and the edge detector ES located at the center in the length direction of the feed roller 6 is a feed roller 6.
The light emitting element es ₁ irradiates the peripheral surface with infrared light and the light receiving element es ₂ receives light reflected from the photosensitive surface of the master sheet X. The light emitting element es ₁ with the lighting control by the CPU, an output signal of the light receiving element es ₂ is used as the input to the control unit CPU by edge detection signal.

FIG. 11 shows the relationship between a control unit CPU for controlling the digital plate making machine DS and each functional element. The control unit CPU includes a light receiving element es ₂ of the edge detector ES and a position immediately before the feed roller 6. Transport sensor PS
_{2. When} the PLL lock signal is input from the laser scanning unit 10, the controller CPU operates the intake roller 31 and the cutter 33 of the sheet roll supply unit 20 via the control unit SU to pull out the photosensitive sheet roll SR. Master sheet X of required length by cutting the cut sheet
Get. Of course, the control unit CPU also controls other functional elements (functional members) such as the master supply unit 40, the developing unit 60, and the fixing unit 90, but these control units are omitted in FIG.

The control device CPU also controls exposure conditions specified by the host computer HC or the local computer RC via the data bus, ie, the length of the master sheet X, the gripper margin before or after the master sheet X,
Compares the print start or print end position information with the comparison register CCR
And part of the information (particularly, the length information of the master sheet X) is updated. However, in the exposure processing by the feed roller 6 and the laser scanning unit 10, the exposure condition of the comparison register CCR and the scanning pulse the contents of the up counter UPC performing counting sensor PS ₃ are always compared by a comparator COM, printing the specified position of the master sheet X is performed by a command of the control unit CPU.

Hereinafter, the actual process from the extraction of the photosensitive sheet roll SR to the end of the exposure will be described with reference to the exposure control flowchart shown in FIG. Intake department guide 3
The join the club sensor PS ₁ preparative annexed to 2 after the presence of the photosensitive sheet roll SR is confirmed, the control unit CPU exposure condition in the comparison register CCR, i.e. the designated master sheet X of length, the master sheet X At the same time as registering any of the gripper margins, print start or print end position information before and after, a clock serving as a reference for synchronous operation is output to the laser scanning unit 10 (step S1).

Next, the controller CPU controls the number of rotations corresponding to the length of the designated master sheet X to be equal to the number of rotations of the intake roller 3.
1 is commanded to rotate, and when this rotation is completed, the cutter 33 is operated, and the sheet pulled out from the photosensitive sheet roll SR is cut as a master sheet X of a required length. Then, the master sheet X is supplied to the master supply unit 40 by the function of the relay roller 34 and the like, and waits on the standby guide plate 41 of the master supply unit 40 (step S2). When it is confirmed that the master sheet X is on standby in the standby guide plate 41, the control device CPU starts an exposure start process (step S3), and outputs a synchronous rotation command to the polygon mirror 11 and the feed roller 6. (Step S4).

[0040] Thereafter, control unit CPU checks (step S5) whether or not reached to the rotation speed of the polygon mirror 11 is completely synchronized, before the master sheet X of the feed roller 6 by the transport unit sensor PS ₂ is Once detected, preparation for detection of the front end edge of the edge detector master sheet X emitting element es ₁ is lit ES is performed (step S6). Therefore, with the rotation of the feed roller 6, when the front end edge of the master sheet X is detected by the edge detector ES (step S7), and scanning of the light receiving element es ₂ by the output of the light receiving element es ₂ illustrate this with counting pulse is started, is turned off light-emitting element es ₁ of edge detector ES after a short time, the infrared light of the same light emitting element es ₁ is exposed to a photosensitive surface of the master sheet X is prevented (Step S8). This step S
In step 8, the exposure is specifically started under the exposure conditions registered in the comparison register CCR. In other words, in this case, the exposure is performed by processing the gripper margins before and after the master sheet X, the margins until the start of printing, and the printing of the image portion by the up counter UPC. And the exposure condition read from the comparison register CCR.

Next, all the printing to be exposed is completed (step S9), and in the latter half of the trailing edge gripper processing,
Light emission is commanded to the light emitting element es ₁ again edge detector ES (step S10), and preparing for the detection of the master sheet X is performed. In this case, part of the master sheet X opposite the edge detector ES are the gripper portion or the rear end margin, the infrared light emitting element es ₁ does not actually occur failures be photosensitive.

[0042] With the synchronous rotational movement of the subsequent feed roller 6, the trailing end edge of the master sheet X is detected by the light receiving element es ₂ of edge detector ES (step S11), and the scan pulse in up counter UPC The counting is terminated immediately and after a short time the edge detector ES
Emitting element es ₁ is turned off in (step S12). Thereafter, the control unit CPU reads the counted scanning pulses from the up counter UPC, and calculates the actual length of the master sheet X from the number of scanning pulses from the relationship between the pulse interval and the number of scanning pulses (step S13). The actual length of the determined master sheet X is compared with the planned length of the master sheet X, and the number of rotations of the take-in roller 31 commanded at the next exposure processing is calculated (step S1).
4).

After these comparisons and calculations, the control device CP
U updates the rotation speed command of the intake roller 31 for the length of the master sheet X registered in the comparison register CCR to the calculated rotation speed command (step S15), and ends the exposure processing.

As described above, as a result of one exposure processing of the master sheet X, the intake roller 31 corresponding to the operation state and the individual difference of the digital plate making machine DS and the inertial mass of the photosensitive sheet roll SR currently used is obtained. The required rotation number information is obtained, and by using this new rotation number information, the correct length of the master sheet X is obtained at the next exposure processing, so that it takes time to mount the master sheet X on the plate cylinder in the subsequent printing process. Disappears.

Next, the details of the detection of the leading edge of the master sheet X by the edge detector ES will be described with reference to the timing chart of FIG. 10 and the control flow of FIG. At the time of the exposure processing by the feed roller 6, first,
The control unit CPU registers the exposure condition, that is, the length of the designated master sheet X, the gripper margin before or after the master sheet X, the print start or print end position information in the comparison register CCR, and simultaneously registers the laser scanning unit. A clock serving as a reference for the synchronous operation is output to 10 (step S21).

Next, the control unit CPU confirms the synchronous movement of the PLL of the polygon mirror 11 of the laser scanning unit 10 (step S22), and thereafter, the control unit CPU makes the polygon mirror 11 of the laser scanning unit 10 completely. It is checked whether or not the synchronized rotation speed has been reached (step S23). Thereafter, the master sheet X is conveyed from the master supply unit 40 (step S24), and the feed roller 6 This master sheet X is the transport unit sensor PS ₂
Is detected (step S).
25) Preparation of detection of the front end edge of the edge detector master sheet X emitting element es ₁ is lit ES is performed (step S26). In this case, as shown in FIG.
While scanning pulse from the scanning pulse sensor PS ₃ already exists, the number of the scanning pulse is not counted.

[0047] Thus, with the rotation of the feed roller 6, when the front end edge of the master sheet X is detected by the edge detector ES (step S27), the light receiving element es ₂ by the output of the light receiving element es ₂ illustrate this with the count starts of the scan pulse from the light-emitting element es ₁ of edge detector ES is turned off after a short time (step S28). That is, as can be understood from FIG. 10, the tip edge of the master sheet X is the light-emitting element es ₁ - When crosses the optical path between the light receiving element es _2, since the output signal of the light receiving element es ₂ rapidly decreases, the Standing Due to the fall, the passage of the leading edge of the master sheet X can be immediately detected.

Thereafter, in step S28, the current laser beam position information from the leading edge of the master sheet X by the up counter UPC and the printing position information under the exposure conditions registered in the comparison register CCR are constantly compared by the comparator COM. When the laser beam position on the surface of the master sheet X matches the print position information registered in the comparison register CCR (step S29), printing is started (step S30). Of course, the printing position on the master sheet X is very accurate because the edge detector ES accurately recognizes the leading edge position of the master sheet X.

As understood from FIG. 10, according to the above-described edge detector ES, the edge detector ES at the trailing edge of the master sheet X can also be accurately detected. That is, before the rear end edge of the master sheet X driven by the feed roller 6 passes, if you turn on the light-emitting element es ₁ of edge detector ES, rear edge are edge detector ES master sheet X Crosses the light receiving element es ₂
Since the output signal of the output signal rapidly increases, it is possible to accurately detect the passage of the trailing edge at the rising edge of the output signal.

[0050]

As is apparent from the above description, according to the first and third aspects of the present invention, it is possible to prepare a printing original by reading various image information handled by a digital computer or the like. The master sheet of the required length can be cut from the photosensitive sheet roll each time, and the master length of the exact length required by the plate cylinder of the printing press is not affected by the inertia weight of the photosensitive sheet roll and the individual differences of the equipment. A master length control method and a control device for a digital plate making machine from which a sheet is obtained can be achieved. According to the second aspect of the present invention, since the scanning pulse for detecting the synchronous rotation of the polygon mirror is output from the laser scanning unit, the scanning pulse is used as a physical quantity corresponding to the rotation angle of the feed roller. This has the effect of simplifying the device configuration. According to the fourth aspect of the invention, the actual length of the master sheet that has passed through the feed roller is measured by an up counter and a comparison register that transmit and receive information to and from the control device via the data bus. It is possible to obtain a digital plate making machine with a simple structure that can use the value calculated from the length when cutting a new master sheet,
According to the fifth aspect of the present invention, the number of revolutions of the intake roller is monitored by the encoder, so that the length of the master sheet to be cut can be made more accurate.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a communication network incorporating a digital plate making machine according to the present invention.

FIG. 2 is an overall sectional view of the digital plate making machine.

FIG. 3 is an enlarged sectional view of a main part of a sheet roll supply unit and a master supply unit of the digital plate making machine.

FIG. 4 is a front view of a leading edge alignment unit of the digital plate making machine.

FIG. 5 is a side view of the tip alignment unit.

FIG. 6 is an enlarged sectional view of a main part of a developing section of the digital plate making machine.

FIG. 7 is an enlarged sectional view of a main part of the developing unit and the fixing unit of the digital plate making machine.

FIG. 8 is an enlarged horizontal sectional view of a main part of a fixing unit of the digital plate making machine.

FIG. 9 is an enlarged sectional view of a main part around a feed roller of the digital plate making machine.

FIG. 10 is a timing chart of each signal in a control section of the digital plate making machine.

FIG. 11 is a block diagram of a control unit of the digital plate making machine.

FIG. 12 is a flowchart of an exposure / printing process of the digital plate making machine.

FIG. 13 is a flowchart of an edge detection operation in the digital plate making machine.

[Explanation of symbols]

CCR Comparison register COM Comparator CPU controller DB Data bus DS Digital plate making machine ES Edge detector es ₁ Light emitting element es ₂ Light receiving element NW Communication network HC Host computer PS ₁ Intake sensor PS ₂ Transport sensor PS ₃ Scan pulse sensor UPC UP Counter RC Local computer SR Photosensitive sheet roll SV server X Master sheet 1 Airframe 1a Bottom wall 1b Upper wall 2 Front door 3 Lower hinge 4 Side door 5 Charger 6 Feed roller 8 Discharge roller 9 Discharge tray 10 Laser Scanning unit 20 Sheet roll supply unit 31 Intake unit roller 32 Intake unit guide 33 Cutter 40 Master supply unit 60 Developing unit 79 Developing solution pump 81 Toner solution pump EB Developing solution bottle TB Toner solution bottle RB Collecting solution Torr 90 fixing unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04N 1/00 108 H04N 1/00 108P

Claims (5)

[Claims] 1. A photosensitive sheet roll of a sheet roll supply section is fed out and cut by a loading section roller to form a master sheet, and the master sheet is supplied to a peripheral surface of a feed roller driven to rotate at a controlled speed in the sub-scanning direction. In a digital plate making machine for main-scanning image information from a laser scanning unit on a photosensitive surface of the master sheet, the front and rear edges of the master sheet can be detected facing the peripheral surface of the feed roller immediately before the scanning position by the laser scanning unit. An edge detector is arranged, a physical quantity corresponding to the rotation angle of the feed roller between the front edge detection and the rear edge detection by the edge detector is measured, and the actual length of the master sheet passed from the physical quantity is measured. Calculate and calculate the rotation speed of the intake roller at the time of the next master sheet A master length control method for a digital plate making machine, wherein the master length is corrected based on a calculation result of the length of the plate. 2. The method according to claim 1, wherein the physical quantity is a scan pulse for each scan obtained by synchronous rotation of a polygon mirror of the laser scanning unit. 3. A photosensitive sheet roll of a sheet roll supply section is fed out and cut by an inlet roller to form a master sheet, and the master sheet is supplied to a peripheral surface of a feed roller driven to rotate at a controlled speed in the sub-scanning direction. In a digital plate making machine for performing main scanning exposure of image information from a laser scanning unit on a photosensitive surface of the master sheet, an edge detector arranged facing a peripheral surface of the feed roller immediately before a scanning position by the laser scanning unit, The front and rear edge information of the master sheet and the physical amount corresponding to the rotation angle of the feed roller are input from the edge detector, and the physical amount of the passed master sheet from the detection of the front edge to the detection of the rear edge of the master sheet is used to calculate the master sheet. A control device for calculating the actual length, the control device comprising: A master length control device for a digital plate making machine, wherein the number of revolutions of an intake roller is corrected based on the previous calculation result of the length of a master sheet at the time of feeding and cutting. 4. A scanning pulse sensor for the physical quantity which outputs a scanning pulse for each scanning obtained by synchronous rotation of a polygon mirror of the laser scanning unit, and a front edge of a master sheet passed by a command of the control device. An up counter that counts scanning pulses from the detection to the detection of the trailing edge, and the length of the master sheet in the exposure information in which the exposure information of the master sheet being processed is registered and registered by the calculation result by the control device. 4. A master length control device for a digital plate making machine according to claim 3, further comprising: a comparison register for updating the rotation speed data of the intake roller regarding the length of the master plate. 5. The master length control device for a digital plate making machine according to claim 3, wherein the number of rotations of the intake roller is monitored by an encoder that is rotated in synchronization with the intake roller. .