JP3613478B2 - Development device for photosensitive lithographic printing plate - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a technique for stabilizing the development sensitivity of a developing device for a photosensitive lithographic printing plate (hereinafter sometimes abbreviated as “PS plate”) while keeping the activity of a developing solution constant during development processing.
[0002]
[Prior art]
In the PS plate developing apparatus, the processing components in the developer decrease with the development processing of the PS plate, and the developing performance deteriorates. Further, when the developer comes into contact with air, carbon dioxide in the air dissolves in the developer and the performance of the developer is degraded. Thus, since the performance of the developer deteriorates with processing and time, a conventional developer replenishing method for maintaining the activity of the developer constant by appropriately replenishing the developer replenisher is disclosed in, for example, There is a technique described in Japanese Patent No. 61-61164. In this technique, the conductivity of the developer is measured, and when the conductivity falls below a preset conductivity, the replenisher is activated to replenish the developer replenisher.
The above replenishment is based on the knowledge that the conductivity decreases when the developer performance decreases, and the developer performance is maintained properly under the condition that the development performance and conductivity are properly associated. Is done.
[0003]
[Problems to be solved by the invention]
For example, the developer is naturally deteriorated by processing the PS plate, but carbon dioxide in the air is always dissolved in the developer, and the developer is also deteriorated by the influence of the dissolved carbon dioxide. Therefore, as replenishment for recovering the performance of the developer, it is necessary to carry out replenishment that compensates for deterioration due to processing of the PS plate and replenishment that compensates for deterioration due to carbon dioxide.
In the configuration in which the conductivity of the developer is measured and the replenisher is replenished according to the conductivity of the developer, as in the technique described in Japanese Patent Laid-Open No. 61-61164, the conductivity for determining the replenishment timing. Must be set, and the set value of conductivity needs to be raised or lowered as appropriate. This is because as the mother liquor replacement rate of the developing solution (ratio of the replenishing solution to the developing mother solution in the developing tank) increases, the appropriate conductivity at that time also increases or decreases.
The relationship between the mother liquor replacement rate and the conductivity is, for example, as shown in FIG. 7 and is determined experimentally, and is set in consideration of deterioration due to carbon dioxide with a constant processing amount per unit time.
[0004]
On the other hand, when the processing frequency of the PS plate is high, the fatigue level due to the processing of the PS plate is large, and when the processing frequency is low, the fatigue level due to the processing of the PS plate is small. Since the fatigue level due to carbon dioxide per unit time is constant, the ratio of the fatigue level due to processing of the PS plate and the fatigue level due to carbon dioxide varies depending on the processing frequency. As a result, the relationship between the above replacement rate for replenishment control and conductivity, which is set as a constant ratio of the fatigue levels of both, changes, and proper replenishment cannot be performed.
Therefore, the development sensitivity cannot be stabilized only by replenishment based only on the electrical conductivity as in the prior art.
In addition, by measuring the processing frequency for each user and setting the relationship between the mother liquor replacement rate and the conductivity according to the processing frequency of the user, proper replenishment is possible, but setting work prior to replenishment is possible. It was complicated.
In addition, in the conventional automatic developing apparatus, if the developer is evaporated, the developer is concentrated, and the conductivity of the developer is apparently increased. There is a risk that replenishment will not occur as a result of the computer's judgment, resulting in a development failure. In order to prevent this, there is a method of replenishing water in anticipation of evaporation that occurs at regular intervals, but the amount of evaporation varies depending on the installation environment and seasonal fluctuations, and it cannot be said that the replenishment system is perfect.
[0005]
An object of the present invention is to solve the above-described conventional problems, and to provide a developing device capable of performing a stable developing process over a long period of time even if a user's processing frequency or installation environment changes.
[0006]
[Means for Solving the Problems]
The above object of the present invention can be achieved by the following constitution.
(1) In a developing device for a photosensitive lithographic printing plate comprising a replenisher for replenishing a developer replenisher when the conductivity of the developer is lower than a set value,
The replenishing device changes a set value of the conductivity based on the measured value, and a processing amount measuring means for measuring a processing amount processed in the one period of the photosensitive lithographic printing plate for each predetermined period. And a storage means for storing an appropriate relationship between the processing amount processed in the one cycle and the conductivity, and the set value of the conductivity of the processing amount processed in the one cycle. A photosensitive lithographic printing plate developing device characterized in that the height is lowered according to an increase or decrease.
[0007]
(2) The electric conductivity has a relationship associated with the replacement rate of the developer, and the electric conductivity corresponding to the predetermined replacement rate is set as a set value for replenishment control. Development device.
[0008]
(3) According to the above (1) or (2), the conductivity supplementary set value is raised or lowered according to the increase or decrease of the processing amount by correcting the relationship between the conductivity and the replacement rate. Development device.
[0009]
[Action]
When the amount of treatment per unit time is small, that is, in a quiet treatment state, the rate of fatigue due to carbon dioxide is greater than the fatigue due to treatment. Since it has been experimentally found that fatigue due to carbon dioxide recovers development sensitivity at a higher conductivity value than fatigue due to processing, when the processing amount is small, the conductivity relative to the replacement rate for replenishment control By increasing the set value, the development sensitivity can be stabilized.
[0010]
Conversely, when the amount of processing per unit time is large, that is, in the continuous processing state, the rate of fatigue due to processing is greater than that due to carbon dioxide. Since it is experimentally known that processing sensitivity recovers with lower electrical conductivity than with carbon dioxide, so setting the conductivity relative to the replacement rate for replenishment control when the throughput is large. By reducing the value, the development sensitivity can be stabilized.
Further, as factors affecting the specific gravity of the developing solution, dissolution of the photosensitive layer, water evaporation, and the specific gravity of the developing replenisher can be considered. That is, when the photosensitive layer is dissolved, the specific gravity of the developer increases if the specific gravity is greater than the specific gravity of the developer. Since water evaporation directly increases the concentration of dissolved components, the specific gravity of the liquid also increases. If the specific gravity of the developer replenisher is larger than the specific gravity of the developer charging solution, the specific gravity of the developer in the developing tank increases as replenishment proceeds and the replacement ratio with the replenisher increases. Therefore, the amount of dissolution of the photosensitive layer, that is, the relationship between the processing area of the PS plate, the specific gravity of the developing solution, and the replacement rate with the replenishing solution is obtained in advance through experiments and programmed to control the amount of evaporation. A stable development process that is not affected can be performed.
[0011]
【Example】
Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a configuration diagram of the developing device. The developing device 1 includes a developing tank 5 that stores a developing solution of the PS plate 3 and performs development processing, and a rinse tank 7 that cleans the PS plate 3 after development. The exposed PS plate 3 is dipped and conveyed in the developer in the developing tank 5 by the conveying roller 9 and subjected to development processing. The developed PS plate 3 is continuously conveyed to the rinsing tank 7 and rinsed by spraying a rinsing liquid.
The developer in the developing tank 5 is blown toward the PS plate 3 while being filtered by the filter 11 and circulated by the pump 13, so that the liquid exchange rate on the surface to be processed of the PS plate 3 is increased. As in this embodiment, the developer in the developing tank 5 is preferably prevented from contacting with the air as much as possible by covering the liquid surface with the floating lid 15. Further, the developing tank 5 may be provided with a cover that airtightly covers the upper space. Moreover, you may provide the rotating brush which rubs a printing plate as a development promotion means.
[0012]
The developing tank 5 includes a developing replenisher replenishing device 17 shown in detail in FIG. The replenishing device 17 includes a keyboard / display device 19, a photoelectric switch 21 that measures the throughput of the PS plate 3, a conductivity sensor 23 that measures the conductivity of the developer, and a specific gravity sensor 25 that measures the specific gravity of the developer. A warning device 27 that issues a warning when an abnormality occurs in the developing solution, each of the replenishing tanks 33 and 35 filled with the replenishing solution 29 and the diluting water 31, and the development replenishment that supplies the replenishing solution 29 to the developing tank 5. Based on signals from the pump 37, the water replenishment pump 39 that supplies the dilution water 31 to the developing tank 5, the keyboard / display device 19, the photoelectric switch 21, the conductivity sensor 23, and the specific gravity sensor 25, a warning device 27, a development replenishment pump 37, a water replenishment pump 39, and the like.
The warning device 27, the development replenishment pump 37, and the water replenishment pump 39 are connected to the controller 41 via operation relays 43, 45, and 47, respectively.
[0013]
The controller 41 is necessary for replenishment of the CPU 49 for controlling the operation of each element, a first memory (RAM) 51 for storing the conductivity set as a reference value for replenishment, and the replenishment amount of each replenisher. A second memory (ROM) 53 storing various information, an input / output port 55, a timer 57, and an A / D converter 59.
In the first memory (RAM) 51, the width information W of the PS plate 3, the replacement rate information X of the developing solution, the period ti for measuring the processing area, the replenishment amount tw of the dilution water based on the measured specific gravity, the measured conductivity The replenishment amount td of the development replenisher based on the above, the measured processing amount S, the processing amount ΔS per unit time, etc. are stored in a rewritable manner.
The second memory (ROM) has a unit dilution water replenishment amount Hw, a water pump flow rate Uw, a unit development replenisher replenishment amount Hd, a development pump flow rate Ud, a transport speed V, a development tank capacity V _t , a specific gravity threshold value, a conductivity 1st threshold value, electrical conductivity second threshold value, each electrical conductivity third threshold value of ΔS1,..., ΔSn, and the like are stored.
[0014]
The replenishing device 17 always measures the conductivity of the developer by the conductivity sensor 23, and replenishes the replenisher 29 and the dilution water 31 in the tanks 33 and 35 when the measured conductivity falls below a set value. It has become.
Further, for example, the photoelectric switch 21 measures the transport amount of the PS plate 3 per unit time, and the CPU 49 calculates an area as a processing amount from the transport amount and the width of the PS plate 3. As a means for calculating the area, a width detection sensor (for example, a device in which a number of micro switches are arranged in a direction orthogonal to the conveyance direction and the width is detected by the number of ON switches) is provided at the insertion port of the apparatus and the time during which the switch is ON It is also good to calculate by product Then, the CPU 49 reads the appropriate conductivity according to the processing frequency from the second memory (ROM) 53, writes the conductivity as a new setting value for replenishment control in the first memory (RAM) 51, Replenishment is always performed based on an appropriate set value.
[0015]
Next, the replenishment operation of the development replenisher will be described. 3 to 5 are flowcharts showing the replenishment control process, FIG. 3 is a replenishment control based on specific gravity, FIG. 4 is a replenishment control based on conductivity, and FIG. 5 is a control for calculating the processing frequency.
In this embodiment, the replenishment control based on the specific gravity of the developer (FIG. 3) is performed prior to the replenishment control based on the conductivity (FIG. 4).
[0016]
First, when the power is turned on (step S1), a cycle ti for calculating the processing frequency of the PS plate 3 is set (step S3). In this embodiment, ti = 24 hours, and the processing frequency is calculated every 24 hours.
When the specific gravity D of the developer is measured by the specific gravity sensor 25 (step S5), the measured specific gravity D is corrected for comparison calculation with reference to the developer replacement rate at that time (step S7). Next, a specific gravity threshold value set in advance for replenishment control is read (step S9), and this threshold value is compared with the corrected measured specific gravity Da to determine whether replenishment is necessary (step S11). If the measured specific gravity Da is larger than the specific gravity threshold value, a predetermined amount of dilution water is replenished (step S13), and the specific gravity of the developer is lowered. Further, if the measured specific gravity Da is smaller than the specific gravity threshold, the dilution water is not replenished, and the control proceeds to the replenishment control based on the next conductivity (FIG. 4).
[0017]
The replenishment control based on the conductivity starts by starting a timer that counts the measurement frequency measurement period (ti = 24 hours) (step S21).
Next, the conductivity R of the developer is measured by the conductivity sensor 23 (step S23). Next, the developer replacement rate X at this time is read from the first memory (RAM) 51, and the measured conductivity R is corrected for comparison calculation based on the replacement rate (step S25). In the case of this example, the corrected measurement conductivity Ra is obtained by the following equation (1).
[0018]
[Expression 1]
Ra = R + (100−x) · (Re−Rs) / 100
Rs: threshold value when the substitution rate is 0% Re: third threshold value, or threshold value when the substitution rate is 100%
Next, the first threshold value of conductivity is read from the second memory (ROM) 53 (step S27), and the first threshold value is compared with the corrected measured conductivity (hereinafter simply referred to as measured conductivity) Ra. Then, it is determined whether or not the measured conductivity Ra is lower than the first threshold value (step S29). When the measured conductivity Ra is lower than the first threshold, it is when the conductivity is too low, which is regarded as abnormal and a warning is issued (step S31).
[0020]
When the measured conductivity Ra is higher than the first threshold value, the second threshold value of the conductivity is then read from the second memory (ROM) 53 (step S33), and the measured conductivity Ra is higher than the second threshold value. It is determined whether it is low (step S35). When the measured conductivity Ra is higher than the second threshold, it is when the conductivity is too high, which is also considered as an abnormality and a warning is issued (step S31).
[0021]
If the measured conductivity Ra is lower than the second threshold value, an appropriate third threshold value Re of the conductivity for replenishment control is read from the first memory (RAM) 51 (step S37). Here, the third threshold value Re is a conductivity threshold value when the replacement rate is 100%, and is a value that is appropriately set based on the calculation result of the processing frequency of the PS plate 3 to be described later. Every time the frequency changes, the third threshold value Re is also rewritten. For example, if the processing frequency is ΔS1, the conductivity Re1 appropriately set corresponding to the processing frequency ΔS1 is used as a set value for replenishment control. Similarly, if the processing frequency is ΔSn, the conductivity Ren appropriately set corresponding to the processing frequency ΔSn is used as a setting value for replenishment control. The conductivity for replenishment control corresponding to the processing frequency is stored in the second memory (ROM) 53. For example, the relationship between the processing frequency and the conductivity as shown in the following formula 2 is stored. .
[0022]
[Expression 2]
Re = Rs + a + c / (ΔS + b)
Re: third threshold value or conductivity threshold value when substitution rate is 100% Rs: conductivity threshold value when substitution rate is 0% ΔS: throughput per unit time a, b, c: constant [0023]
When the processing frequency is high, the third threshold value Re is set low, and when the processing frequency is low, the third threshold value Re is set high.
When the third threshold value Re is set, a characteristic curve of conductivity relative to the substitution rate is determined by the conductivity threshold value Rs when the substitution rate is 0%, and the measured conductivity Ra corrected by this characteristic curve. However, the replenisher is replenished when it falls below the third threshold value Re.
[0024]
When the third threshold value Re having an appropriate conductivity is read, it is determined whether or not the measured conductivity Ra is greater than the third threshold value Re (step S39). If the measured conductivity Ra is smaller than the third threshold value Re, a predetermined amount of the developer replenisher is replenished (step S41), and the conductivity of the developer is increased.
When the measured electrical conductivity Ra is larger than the third threshold value Re, it is a time when replenishment of the developing replenisher is unnecessary, and therefore, the processing frequency calculation (FIG. 5) is performed without replenishment. When the predetermined replenishment is performed (step S41), the developer replacement rate is updated according to the replenished amount (step S43), and the process shifts to the processing frequency calculation (FIG. 5).
As described above, when a predetermined amount of the replenisher 29 and the dilution water 31 are replenished in the developing tank 5, the decreased activity of the developer is recovered and good development can be performed.
[0025]
Next, the processing frequency calculation shown in FIG. 5 will be described.
The photoelectric switch 21 detects the PS plate 3 (step S51), the detection signal of the PS plate 3 to measure the total processing amount t _i by going cumulatively added (step S53), then in operation timing of the processing frequency It is determined whether or not there is (step S55). When it is not the calculation time of the processing frequency, that is, when 24 hours have not elapsed since the previous calculation of the processing frequency, it is determined whether the power is OFF without calculating the processing frequency (step S65). If the power is not OFF, the process returns to step S where the measurement of the processing frequency cycle is resumed, and the same contents are repeated.
[0026]
If it is determined in step S55 that the processing frequency is being calculated, the width W and the conveyance speed V of the PS plate 3 are read from the second memory (ROM) 53 (step S57), and the PS is calculated from these values and the measured length. The processing area S of the plate 3 is calculated (step S59). Next, a processing amount ΔS per unit time (per 24 hours in this example) is calculated from the processing area S of the PS plate 3 (step S61). Next, the processing amount ΔSn is written and updated in the first memory (RAM) 51 (step S63), and when reading the third threshold value of the next conductivity, the conductivity Rn corresponding to ΔSn is used for replenishment control. It is set as the third threshold value and used for replenishment.
Therefore, replenishment control can be performed based on the appropriate set conductivity according to the processing frequency at that time, and the activity of the developer is stabilized even if the processing frequency changes or environmental conditions change. be able to.
[0027]
Hereinafter, specific setting of the conductivity will be described with reference to FIG. When the operation is started, the replenishment control is performed by comparing the measured conductivity Ra corrected by a straight line (for example, a, b, c, d) in FIG. 6 with the third threshold value Re. The cycle for changing the set value for replenishment control is, for example, 24 hours. In this example, the processing amount per 24 hours is 0 m ² / day, 10 m ² / day, 50 m ² / day, and 100 m ² / day. . The replacement rate is 30% when the processing amount is 10 m ² / day, the replacement rate is 60% when the processing amount is 100 m ² / day, and the processing rate is 50 m ² / day. The substitution rate is 70%.
Substituting Rs = 50, a = 10, b = 28, and c = 280 as constants obtained by experiments in the above formula 2, the following formula 3 is obtained.
[0028]
[Equation 3]
Re = 60 + 280 / (ΔS + 28)
[0029]
In Equation 3, when the processing amount ΔS changes as 0 m ² / day, 10 m ² / day, 50 m ² / day, and 100 m ² / day, the third threshold value Re is 70, 67.4, 63.6. , 62.2.
Therefore, immediately after the start of processing, when the amount of processing ΔS is 0 m ² / day, the third threshold value Re is 70, and therefore, from the conductivity threshold value Rs at a substitution rate of 0%, the sign in FIG. A straight line indicated by a is set. Then, the measured conductivity R is corrected based on this characteristic curve. As a result, when the processing amount is calculated, that is, immediately after the processing is started, the replenishment control is performed based on the straight line with the third threshold value Re being 70.
[0030]
In the next processing amount calculation (the developing solution replacement rate at this time is set to 30%, for example), when the processing amount ΔS increases by 10 m ² / day, the third threshold value Re is 67.4. From the conductivity threshold value Rs at a substitution rate of 0%, a straight line indicated by symbol b in FIG. 6 is set. The measured conductivity R is corrected by this characteristic curve. As a result, when the processing amount is calculated, that is, after the replacement rate reaches 30%, the replenishment control is performed based on the straight line with the third threshold value Re of 67.4.
Similarly, in the next processing amount calculation (the replacement rate at this time is 60%), when the processing amount ΔS increases to 100 m ² / day, the third threshold value Re becomes 62.2 from the above equation 3, and the replacement A straight line indicated by reference sign d in FIG. 6 determined by the conductivity threshold value Rs and the third threshold value Re at a rate of 0% is a straight line for replenishment control, and the measured conductivity R is corrected according to this straight line. . Then, after the replacement rate of 60%, replenishment control is performed based on this straight line.
[0031]
Similarly, in the next processing amount calculation (the replacement rate at this time is 70%), when the processing amount ΔS decreases by 50 m ² / day, the third threshold value Re becomes 63.6 from the above equation 3, and the replacement A straight line indicated by symbol c in FIG. 6 determined by the conductivity threshold value Rs and the third threshold value Re at a rate of 0% is a straight line for replenishment control, and the measured conductivity R is corrected according to this straight line. . Then, after the replacement rate of 70%, replenishment control is performed based on this straight line.
As a result, the replenishment control straight line has a characteristic in which straight lines having different slopes D are set between the respective replacement rates, as shown in FIG. 6, and the replenishment control line is replenished according to the relationship between the replacement rate and the conductivity indicated by the characteristic line. Determine the necessity of
[0032]
【The invention's effect】
According to the present invention, even if the development processing frequency of the PS plate changes, an appropriate conductivity corresponding to the processing frequency at that time is set as a threshold value for replenishment control. Even if the frequency varies, the activity of the developer can be stabilized and the development performance can be kept constant. Therefore, a good development performance can always be obtained without being influenced by factors such as the environment.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a PS plate developing apparatus.
FIG. 2 is a block configuration diagram of a replenishing device.
FIG. 3 is a flowchart of replenishment control based on specific gravity.
FIG. 4 is a flowchart of replenishment control based on conductivity.
FIG. 5 is a flowchart for calculating and setting a processing frequency.
FIG. 6 is a graph showing the relationship between the replacement rate used for the replenishment control and the conductivity in the embodiment of the present invention.
FIG. 7 is a graph showing a relationship between a replacement rate and conductivity used in conventional replenishment control.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 PS plate developing device 3 PS plate 5 Developing tank 7 Rinse tank 9 Conveying roller 13 Pump 17 Replenisher 21 Photoelectric switch 23 Conductivity sensor 25 Specific gravity sensor 29 Developer replenisher 31 Diluted water 33 Replenisher tank 35 Diluted water tank 37 Developer replenishment Pump 39 Water replenishment pump 41 Controller 49 CPU
51 First memory (RAM)
53 Second memory (ROM)
57 timer

Claims (3)

In the developing device for a photosensitive lithographic printing plate provided with a replenishing device for replenishing a developing replenisher when the conductivity of the developer is lower than a set value,
The replenishing device changes a set value of the conductivity based on the measured value, and a processing amount measuring means for measuring a processing amount processed in the one period of the photosensitive lithographic printing plate for each predetermined period. And a storage means for storing an appropriate relationship between the processing amount processed in the one cycle and the conductivity, and the set value of the conductivity of the processing amount processed in the one cycle. A photosensitive lithographic printing plate developing device characterized in that the height is lowered according to an increase or decrease. The developing device according to claim 1, wherein the conductivity has a relationship associated with a replacement rate of the developer, and the conductivity corresponding to the predetermined replacement rate is set as a set value for replenishment control. 3. The developing device according to claim 1, wherein the set value for replenishing the conductivity is lowered in accordance with the increase or decrease in the processing amount by correcting the relationship between the conductivity and the replacement rate.

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