Automatic processing method of photosensitive lithographic printing plate and automatic processing apparatus thereof

An automatic processing apparatus of a photosensitive lithographic printing plate equipped with a replenishing device for replenishing a developer replenisher when an electric conductivity value of a developer in a development tank is lower than a target electric conductivity value as previously calculated, wherein

• the replenishing device is provided with an electric conductivity sensor for detecting the electric conductivity value of the developer in the development tank, a replenisher supply unit for supplying the developer replenisher to the development tank, a timer for detecting an elapsed time after replenishing the developer replenisher until next replenishment, and a control unit for setting up the target electric conductivity value as a standard for replenishing the developer replenisher and controlling the action of the replenisher supply unit such that when the electric conductivity value of the developer in the development tank becomes lower than the target electric conductivity value as set up, the developer replenisher is replenished, and
• the control unit corrects the target electric conductivity value using a first operation expression as previously defined for every replenishment of the developer replenisher during a period from immediately after start of operation of an automatic processing apparatus until the measured electric conductivity value of the developer exceeds the target electric conductivity value and corrects the target electric conductivity value using a second operation expression for every replenishment of the developer replenisher after the measured electric conductivity value of the developer first exceeds the target electric conductivity value after start of operation of the automatic processing apparatus, based on the detected values of the electric conductivity sensor and the timer.