JP3214405B2 - Wet plate making machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet plate making machine for producing an original plate for printing, and more particularly, to a toner density detecting section used for a developing device.

[0002]

2. Description of the Related Art As is well known, in a wet plate making machine for producing an original plate for printing, a developer is ejected from a spray nozzle to develop a toner image into a latent image forming master sheet. The toner concentration of the circulating developer in the liquid tank needs to be maintained at a substantially constant value. For this reason, a concentration detecting unit for detecting the toner concentration of the circulating developing solution is attached to the developing solution tank of the developing device described above, and the toner supply pump is controlled by a signal from the density detecting unit,
The toner concentration in the developer tank is maintained within a predetermined range.

A conventional density detecting unit used for this purpose is composed of a light emitting element and a light receiving element sandwiching a light transmitting cell such as a transparent glass tube through which a circulating developer flows. The transmitted light amount from the light emitting element is received by the light receiving element, and the toner concentration of the developing solution flowing through the light transmitting cell is detected.

[0004]

However, in the control of the developing device by such a concentration detecting unit, the toner concentration of the developing solution in the developing solution tank tends to increase with the operation. In other words, in an actual wet plate making machine, the surface of the light transmitting cell, the light emitting surface of the light emitting element, the light receiving surface of the light receiving element are dust and the like inside the machine, and the inner wall surface of the light transmitting cell is in the circulating developer. Since the toners are respectively stained, the actual toner density differs even with the same light receiving intensity of the light receiving element.

For this reason, conventionally, during a regular or irregular maintenance work of a wet plate making machine, the density detecting unit is cleaned so that the same light receiving intensity of the light receiving element can be obtained at a specific light emitting intensity of the light emitting element. Maintenance.
However, such maintenance and management work is not only a time-consuming task, but it is also necessary to remove the light transmission cell from the developer tank and clean the inner wall surface in order to perform the intended work strictly. You.

SUMMARY OF THE INVENTION In view of the above-described problems of the conventional developing device of a wet plate making machine, the object of the present invention is to provide a light emitting surface of a light emitting element of a density detecting unit, a light receiving surface of a light receiving element, and an inner wall surface of a light transmitting cell. It is an object of the present invention to provide a wet plate making machine capable of accurately measuring the toner concentration irrespective of dirt and the like, and notifying an unadjustable state.

[0007]

According to the present invention, there is provided a spray nozzle for ejecting a developing solution onto a surface of a master sheet to which image information has been exposed, and a density detecting unit for detecting a toner density of a circulating developing solution. A control device that receives an output signal from the density detection unit, the density detection unit includes a light-emitting unit and a light-receiving unit that face each other across a light transmission cell through which a circulating developer flows, The apparatus causes the light emitting unit to emit light a plurality of times at different light emitting intensities at the time of calibration of the concentration detecting unit, reads the light receiving intensity of the light receiving unit at each of these light emitting times, and sets the light emitting unit to be set from these light receiving intensities. Set the luminous intensity to be used, and if the luminous intensity read from the light receiving unit is not within the specified range, reach by the wet plate making machine that sends an “alarm” signal indicating that the adjustment is not possible. It is.

[0008]

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 transmitted 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 the laser scanning unit 10 of the digital plate-making machine DS described later in detail.
The image information is transmitted together with the synchronization signal to the (exposure device) at a necessary timing. 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 an entire digital plate making machine DS according to the present invention, and a roll paper supply section 20 for pulling out a sheet from a 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 roll paper supply unit 20 and is then charged on the surface by a charger 5 and strictly rotates synchronously with a stepping motor (not shown). It is supplied to the peripheral surface of the feed roller 6 (exposure device).

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. The master sheet X, on the surface of which the image information has been made into a latent image, is conveyed to a developing device 60 adjacent to the left side of the feed roller 6, and after the developing device 60 develops the image information, the fixing device 90
The fixing device 90 heats and fixes the toner image, and the toner image is collected on the paper discharge tray 9 by the function of the paper discharge roller 8 located on the left side of the machine frame 1.

FIG. 3 shows the details of the roll paper supply unit 20 and the master supply unit 40 described above.
Is provided with a tiltable hanger 21 on which a photosensitive sheet roll SR can be mounted.
The suspended hanger 21 suspended by the photosensitive sheet roll S
The center bar 23 has a jaw portion 21a on which the center bar 23 of R is hung. 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 through the jaw portion 21a. Can be multiplied. A gas stay 24 is provided between the bottom wall 1a of the body frame 1 and the tilt hanger 21 for applying a lift to the heavy tilt hanger 21. The gas stay 24 connects the lower bracket 25 and the support shaft 22 to each other. When the dead center is exceeded, a counterclockwise rotation moment about the tilt hanger 21 about the support shaft 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 middle portion of the side door 4 and the middle portion of the tilt hanger 21. 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 roll paper 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 transition to the section 40 and a transition section Mylar sheet 35 are provided. The amount of rotation of the intake section roller 31 is strictly monitored by the rotation of an attached encoder 36, and the cutter 33 is required by the intake section roller 31. When a long sheet is pulled out, the sheet is cut by a command signal. 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. Therefore, the master sheet X fed from the relay roller 34 is smoothly guided on the standby guide plate 41. In addition,
Since the above-described relay roller 34 is rotated for a fixed time according to the support of the server SV, the long master sheet X
Are on standby in a state of being bent on the surface of the standby guide plate 41.

The master supply section 40 includes a standby guide plate 41 extending obliquely upward toward the charger 5, and an intermediate portion of the standby guide plate 41 can be pressed 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 alignment pieces 48 facing in the width direction of the standby guide plate 41 are fixed to an intermediate portion of the alignment shaft 46, and these alignment 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 device 60 following the feed roller 6. The developing device 60 has a master sheet on which image information is converted into a latent image via a transition portion guide plate 61 and a transition portion roller 62. X is supplied. That is, the developing device 60 includes an inlet roller 63A that is arranged in the moving direction of the master sheet X, a spray nozzle 63 that sprays the 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 64A, 64B;
A scraping blade 65 for scraping the developer adhered to the peripheral surface of one of the peripheral surfaces 64A is brought into contact with the peripheral surface as necessary.

FIG. 7 shows the details of the scraping blade 65 and its operating mechanism.
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. 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 device 60 develops the master sheet X, the blade actuator 67 is temporarily excited, and the operating rod 67 a and the tilt rod 69 move rightward against the force of the return spring 72. And scraping blade 6
The blade 5 and the blade supporting member 73 are slightly rotated to the position shown by the dashed line, and the tip of the scraping blade 65 is brought into contact with the peripheral surface of the squeezing roller 64A, and the excess developer on the peripheral surface is written off. . Then, the dirty aperture rollers 64A, 64B
For cleaning, the squeezing rollers 64A, 64
To remove B, it is only necessary to hang a fingertip on a finger hook 73a at an intermediate portion of the blade support member 73 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, the squeeze rollers 64A and 64B are re-installed in the mounting groove 66, and the blade support member 73 in the state indicated by the two-dot chain line is tilted clockwise. Maintenance can be performed.

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 developer replenishing pump 79 and a toner replenishing pump 81 are provided immediately below a mount 78 on which the developer tank 77 is provided.
A pump stand 82 on which a developer circulation pump 79A (shown in FIG. 10) is mounted is located on the back side, and a developer bottle EB,
A bottle stand 83 on which a liquid toner bottle TB and a collected liquid bottle RB can be installed is provided.

A developer supply pump 79 and a toner supply pump 81, a developer bottle EB, a liquid toner bottle TB,
Explaining the relationship with the recovery liquid bottle RB, the discharge port 79a of the developer supply pump 79 is connected to the lower part of the developer tank 77 via a discharge pipe 83A and the suction port 7a.
9b is the developer bottle E via the developer supply line 84.
B. Although not shown in FIG. 6, the discharge port of a developer circulation pump 79A (shown in FIG. 10) that connects the suction side to the developer inside the developer tank 77 is connected to the spray nozzle 63 described above. The developer in the developer tank 77 is circulated. As shown in FIG. 6, the developer tank 77 is provided with a liquid amount upper limit detection switch LS1 and a liquid amount lower limit detection switch LS2 for monitoring the liquid level of the stored developer. Detection switch LS
1 and the output signal of the liquid level lower limit detection switch LS2 are input to the control unit CPU of FIG. 10 via the data bus, and the output signal of the control unit CPU controls the developer supply pump 79. Since the collection pipe 85 connected to the bottom of the developer tank 77 has an opening / closing cock 86 at an intermediate portion,
By opening the opening / closing cock 86 as necessary,
The developing solution in the developing solution tank 77 can be collected in the collecting solution bottle RB.

The developer tank 77 is provided with a concentration detecting unit TS shown in FIG. 9, which monitors the toner concentration of the developer contained in the developer tank 77. That is, the light transmitting cell 89 of the same concentration detecting unit TS composed of a transparent glass tube has one end connected to the developing solution in the developing solution tank 77 and the other end connected to the collecting pipe 8.
5, the developer in the developer tank 77 flows through the light transmitting cell 89. Further, on both sides of the light transmitting cell 89, a density detecting unit light emitting portion TS1 and a density detecting unit light receiving portion TS2 are disposed to face each other with a density filter FL interposed therebetween. The light of TS1 is received by the light receiving unit TS2 of the density detecting unit, and the output signal of the light receiving unit TS2 of the density detecting unit is input to the control unit CPU of FIG. 10 via a data bus. The supply pump 81 is controlled. That is, the suction port 81a of the toner supply pump 81 is connected to the liquid toner bottle TB via the toner pipe 87,
Since the discharge port is connected to the inside of the developer tank 77 via a toner supply pipe 88, the master which supplies the toner concentration of the developer in the developer tank 77 by driving the toner supply pump 81 is provided. A value suitable for sheet X is maintained.

FIGS. 7 and 8 show details of the fixing device 90. The fixing device 90 has a fixing device housing extending in the width direction of the master sheet X to be passed. , An upper housing 91A and a lower housing 91B located above and below. Also, as understood from FIG.
At both ends of the fixing device housing inside the upper wall portion 1b, fan motors 92 for taking in the internal air from the position facing the corresponding upper wall portion 1b are attached, respectively. On the discharge side, that is, on the inner side, a ceramic heater 93 that can heat the discharged internal air and a honeycomb rectifying plate 94 that rectifies the heated internal air are arranged. Further, ventilation holes 94 and 95 are formed in the end plate 91C of the fixing device housing so that a part of the heated air inside the fixing device housing is diverted to the upper wall portion 1b side. By partially circulating the heated air, drying of the master sheet X in cold weather is promoted.

Since the fixing device 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. 11 is a control flow of the developer processing in the developing device 60. When the digital plate making machine DS is started, the developer circulating pump 79A is started and the developer tank 77 is started.
The developing solution inside is stirred (step S1). Next, the control device CPU calls the detection results from the liquid amount upper limit detection switch LS1 and the liquid amount lower limit detection switch LS2 (step S2), and checks whether the liquid level of the developer in the developer tank 77 is within an appropriate range. Is checked (step S
3). If the liquid level is within the proper range, the control device CPU next reads a toner density signal in the developer from the density detection unit TS (step S4), and supplies the master sheet to which the toner density signal is supplied. It is checked whether it is maintained within a range suitable for X (step S)
5). If the toner concentration in this step S5 is appropriate, the developer concentration control ends.

In the case of the check in step S3,
If the liquid level of the developer in the developer tank 77 is not within the proper range, it is determined whether or not this liquid level is below the proper level (step S6). The control device CPU issues a start command to the developer supply pump 79, a new developer is supplied from the developer bottle EB into the developer tank 77 (step S7), and the process returns to before step S4. Note that, in the determination in step S6,
If the liquid level is equal to or higher than the appropriate level, the controller CP
U determines that the developing solution in the developing solution tank 77 overflows due to some abnormality, transmits an "overflow alarm", and ends the operation (step S8).

If it is checked in step S5 that the toner density is abnormal, it is determined whether the toner density is below an appropriate range (step S9).
If the toner concentration is below the appropriate range, the control unit CPU
Instructs the toner supply pump 81 to start up and urges toner supply (step S10).
During the operation 1, the change in the toner concentration of the developing solution is monitored by the concentration detecting unit TS (step S11), and the toner liquid is supplied from the liquid toner bottle TB into the developing solution tank 77 under the monitoring of the concentration detecting unit TS. The developer concentration in the developer tank 77 is maintained within a range suitable for the supplied master sheet X.

If the toner concentration of the developing solution in the developing solution tank 77 exceeds an appropriate range at the time of checking in step S9, the control unit CPU executes the developing solution replenishing pump 79.
Is started to supply a new developing solution from the developing solution bottle EB into the developing solution tank 77 (Step S12), and the process returns to Step S11.

Further, in the case of monitoring the toner concentration in the developer tank 77 in step S11 described above, if the toner concentration does not change, the control unit CPU determines whether the toner in the liquid toner bottle TB or the developer in the developer bottle EB is present. Is determined to be insufficient, and an "insufficient alarm" is transmitted (step S1).
3) The processing operation is terminated until the toner in the liquid toner bottle TB or the developer in the developer bottle EB is supplied.

FIG. 12 shows a density detection unit TS using a standard density filter for accurate density detection.
Is the control flow of the calibration of
6, the developer is discharged, the light transmitting cell is emptied, and the standard filter FL is set in the optical path of the density detecting unit TS (step S21). First, the light emitting section TS1 of the density detecting unit TS is scheduled. Light is emitted at an emission intensity V1,
In this case, the light receiving intensity D1 is equal to the density detecting unit light receiving unit TS.
2 is read (step S22). This received light intensity D
1 is compared with a predetermined lower limit received light intensity DL by the control device CPU (step 23), and is compared with the lower limit received light intensity DL by D.
If 1 is equal or greater, the control unit CPU instructs the density detecting unit light emitting unit TS1 to emit light at the light emitting intensity V2, and the light receiving intensity D2 of the density detecting unit light receiving unit TS2 at the light emitting intensity V2 is transmitted to the control unit CPU. It is input again (step S24).

Thereafter, the control unit CPU checks whether or not the received light intensity D2 is smaller than a predetermined upper limit received light intensity DH (step S25). Is calculated, the density detecting unit light emitting section TS1 is caused to emit light with the light emitting intensity V0, the light receiving intensity of the density detecting unit light receiving section TS2 is read (step S26), and the light receiving at this light emitting intensity V0 is performed. Is repeated until "D0" is reached (step S27).

After the above steps, the control unit CPU causes the density detecting unit light emitting section TS1 to emit light of "V" based on V0, and based on the amount of light received by the density detecting unit light receiving section TS2, A developer concentration graph corresponding to the filter FL is read (step S28). Then, the control device CPU saves the parameters of the developer concentration graph as adjustment values, outputs the adjustment values to the toner supply pump 81, and the toner supply pump 81 controls the concentration of the developer (step S29). .

If D1 is smaller than DL in step S23, the flow advances to step S30 to cause the density detecting unit light emitting section TS1 to emit light again with the value "α" added from V1. Return to before. In this case, the light emission intensity V1 + α is equal to the predetermined light emission intensity V1ma.
When x has been reached (step S31), it is recognized that the adjustment is impossible, and an alarm is issued (step S32).

Similarly, if D2 is greater than DH in step 25, the process also proceeds to step S33, where V2
The density detecting unit light emitting section TS1 is caused to emit light again with the value "α" subtracted from the light emission intensity V2mi.
If it becomes smaller than n (step S34), it is recognized that the adjustment is not possible, an "alarm" is issued (step S32), and the process ends.

In the description of the above embodiment, the present invention is applied to a digital plate making machine DS. However, the present invention is applied to a wet plate making machine having a document table and an exposure stage. Can also be applied.

[0038]

As is apparent from the above description, according to the present invention, when the light emitting surface of the light emitting element of the density detecting unit, the light receiving surface of the light receiving element, the inner wall surface of the light transmitting cell, etc. become dirty,
Even if these cleanings are not performed, the light emission intensity is automatically corrected according to the current light receiving condition, and if the light emitting surface of the light emitting element, the light receiving surface of the light receiving element, the inner wall surface of the light transmitting cell, etc. become abnormally dirty, Cleaning can be prompted by the "alarm" signal, thereby preventing malfunction.

[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 roll paper 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 device of the digital plate making machine.

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

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

FIG. 9 is an enlarged exploded perspective view of a density detection unit provided in a developing device of the digital plate making machine.

FIG. 10 is a block diagram of a developing device control unit of the digital plate making machine.

FIG. 11 is a flowchart of a developer processing of the digital plate making machine.

FIG. 12 is a flowchart of a calibration operation of the density detection unit.

[Explanation of symbols]

 CPU control device DB Data bus DS Digital plate making machine FL Density filter LS1 Liquid amount upper limit detection switch LS2 Liquid amount lower limit detection switch NW Communication network HC Host computer RC Local computer SR Photosensitive sheet roll SV server TS Concentration detection unit TS1 Concentration detection unit Light emitting unit TS2 Concentration detection unit light receiving section X Master sheet 1 Body frame 1a Bottom wall 1b Top 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 Roll Paper supply unit 40 Master supply unit 60 Developing device 63 Spray nozzle 76 Developer vat 77 Developer tank 79 Developer supply pump 79A Developer circulation pump 81 Toner supply pump 89 Light transmission cell 90 Fixing device

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 15/11 B41C 1/00

Claims (1)

(57) [Claims] 1. A spray nozzle for ejecting a developing solution onto the surface of a master sheet exposed with image information, a density detecting unit for detecting a toner concentration of a circulating developing solution, and a control for inputting an output signal from the density detecting unit. Equipment,
The concentration detection unit includes a light-emitting unit and a light-receiving unit opposed to each other with a light-transmitting cell through which the circulating developer flows, and the control device performs a plurality of times with different light emission intensities during calibration of the concentration detection unit. The light emitting unit is caused to emit light, the light receiving intensity of the light receiving unit is read for each light emission, the light emitting intensity used by the light emitting unit is set based on the light receiving intensity, and the light receiving intensity read from the light receiving unit is specified. A wet plate-making machine characterized by transmitting an "alarm" signal indicating an unadjustable state when it is not within the range.