Method and apparatus for automatically controlling an activity of a developing liquid for use in a developer

摘要

A method and apparatus for automatically controlling an activity of a developing liquid for use in a developer are disclosed. A blackening area rate detector detects a blackening area rate of a film developed and outputs an analog signal to a voltage-frequency converter which converts it into a digital signal. The digital signal is sent to a dividing counter which frequency-divides it and outputs a supplement signal to an up-down counter. The up-down counter is counted up by the supplement signal to output a high level signal to a timer via a gate. The timer is actuated by the high level signal to actuate a valve so as to supply a supplemental developing liquid to a developing tank. The gate is closed by using the output signal of the timer during the actuation of the timer. The up-down counter is counted down by the high level signal passed through the gate.