Radiation imagery chemistry: process – composition – or product th – Including control feature responsive to a test or measurement
Reexamination Certificate
2001-02-05
2002-07-23
Le, Hoa Van (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Including control feature responsive to a test or measurement
Reexamination Certificate
active
06423458
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a monitoring method of a developing solution used in processing a large number of lithographic printing plates by use of an automatic developing processor.
BACKGROUND OF THE INVENTION
It has hitherto been known that developing solutions deteriorated by development of a large number of lithographic printing plates are allowed to recover by replenishment of replenishers. For example, JP-A-1-21451 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”) discloses that a process of measuring the electric conductance, comparing the measured value with the electric conductance showing the optimum development activity, which has previously been determined by an experiment, and replenishing a development replenisher when the measured value is lower, thereby keeping the development activity of the developing solution proper. Further, JP-A-4-172355 discloses a process of measuring the amount of a dissolved light-sensitive layer by measurement of the total organic carbon concentration in a developing solution, and replenishing a replenisher according to the measured amount.
Still further, JP-A-58-95349 discloses a process of providing a sensor for electrically measuring the degree of elution of a light-sensitive layer of a non-image area of a light-sensitive plate, and replenishing a development replenisher when the degree of elution is decreased to a specified level.
JP-A-61-61164 discloses a process of measuring the electric conductance, and replenishing a development replenisher when a set level of the electric conductance rises with the processing amount to reach a set value or less.
However, the process of JP-A-1-21451 has the problem that the development activity can not be kept normal under some circumstances, from the fact that the electric conductance of the developing solution also changes with spontaneous evaporation of water in the developing solution. Further, the process of JP-A-4-172355 has the problem that some kinds of organic carbons existing in the developing solution can not be accurately measured in the amount of the dissolved light-sensitive layer, and can not be applied to, for example, a developing solution mainly containing an organic substance as described in JP-A-9-274324. In addition, a process has already been known in which a reduction in processing ability of a developing solution is estimated from the integrated processing area of lithographic printing plates and the integrated operation time of a processor, and a development replenisher is replenished according thereto. In this case, however, it is impossible to recognize the amount and the kind of dissolved light-sensitive layer directly contributing to a reduction in activity of the developing solution, resulting in unstable development activity. For example, no consideration is given to the difference between the case where one side is printed and the case where both sides are printed, changes in the kind of printing plate, and changes in area ratio of an image area to a non-image area.
Further, conventional processes each have the problem that a set value for directing replenishment is not accurately obtained because of changes in ingredient concentration (changes in the concentration rate) of a developing solution which can occur by evaporation of water or back flow of water from a water washing unit, resulting in failure to conduct replenishment. Furthermore, it is necessary to change a control value as the developing solution in a developing tank is substituted by a replenisher, and the substitution rate is detected by the operation time of a pump and integration of the discharge amount. Accordingly, there is the problem that the detecting accuracy is inferior, which causes failure to accurately obtain the set value for directing replenishment.
SUMMARY OF THE INVENTION
An object of the present invention is to keep the development activity of a developing solution good and stable, upon processing a large number of (photosensitive) lithographic printing plates using the automatic developing processor, and to overcome the disadvantages of the conventional processes as described above.
A further object of the present invention is to improve the disadvantages of the conventional processes as described above, and more particularly, to provide a method for monitoring a developing solution so that a set value for directing replenishment can be accurately obtained by accurately detecting the substitution rate of a replenisher for a developing solution, and further by accurately detecting the concentration rate of the developing solution.
The objects of the present invention are attained by the following monitoring method of a developing solution for lithographic printing plates:
(1) A monitoring method of a developing solution for lithographic printing plates, which comprises, when a large number of lithographic printing plates are processed by use of an automatic developing processor, adding a tracing substance stable under alkaline conditions to light-sensitive layers of the lithographic printing plates, or one or both of the developing solution which has been provided at the beginning of development and a development replenisher, and then measuring the amount of the tracing substance in the developing solution during development, thereby judging processing ability of the developing solution;
(2) The monitoring method described in the above (1), wherein when a large number of lithographic printing plates are processed by use of the automatic developing processor, the tracing substance stable under alkaline conditions is added to the light-sensitive layers of the lithographic printing plates, and the amount of the tracing substance dissolved in the developing solution is measured, thereby judging processing ability of the developing solution;
(3) The monitoring method described in the above (1), wherein when the lithographic printing plates are processed by use of the automatic developing processor while replenishing the developing solution which has been provided at the beginning of development with the development replenisher, the tracing substance stable under alkaline conditions and not contributing to development is added to one or both of the developing solution which has been provided at the beginning of development and the development replenisher, in different concentrations when added to both, and then the amount of the tracing substance in the solution during development is measured, thereby determining the substitution rate of the development replenisher for the developing solution which has been provided at the beginning of development;
(4) The monitoring method described in the above (1), wherein when the lithographic printing plates are processed by use of the automatic developing processor while replenishing the developing solution which has been provided at the beginning of development with the development replenisher, the tracing substance stable under alkaline conditions and not contributing to development is added to one or both of the developing solution which has been provided at the beginning of development and the development replenisher, in different concentrations when added to both, the amount of the tracing substance in the solution during development is measured, thereby determining the substitution rate of the development replenisher for the developing solution which has been provided at the beginning of development, and the substitution rate is further compared with the substitution rate determined from the integrated discharge amount of a pump of the automatic developing processor, thereby determining the concentration rate of the developing solution;
(5) The monitoring method described in the above (1), wherein when the lithographic printing plates are processed by use of the automatic developing processor while replenishing the developing solution which has been provided at the beginning of development with the development replenisher, the different tracing substances stable under a
Burns Doane , Swecker, Mathis LLP
Fuji Photo Film Co. , Ltd.
Le Hoa Van
LandOfFree
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