DEVELOPING METHOD OF PHOTOSENSITIVE LITHOGRAPHIC PRINTING PLATE

摘要

PURPOSE:To perform development with uniform quality in the stage of using an automatic developing device to develop many sheets of photosensitive lithographic printing plates by providing means for compensating concentration of a developing soln. as a result of evaporation of the wafer therein so that the concn. of the developing soln. is maintained always in a specified range. CONSTITUTION:A photosensitive lithographic printing plate 2 is conveyed in an arrow direction and a developing soln. 5 consisting of an aq. soln. contg. inorg. ions is sprayed from plural pieces of nozzles 3 provided above the conveying path to the surface of the photosensitive layer of the plate 2 by which the automatic developing processis executed. The conductivity value of the developing soln. 5 contained in a developing tank 4 is measured with a sensor 10 in this stage and when the conductivity valut attains the prescribed value higher than the initial conductivity value, an aq. soln. 12 contg. the component contained in the soln. 5 at the concn. lower than the concn. in the developing soln. is added at a specified rate into the soln. 5 via an automatic metering means 11 by which the development is performed while the concn. of the soln. 5 is maintained always in a specified range.