LIQUID CONCENTRATION CONTROL DEVICE

摘要

PURPOSE:To control liquid concn. within a desired optimum range and obtain always stable liquid concn. by comparing the reference signal by the light of a light source through a filter and the detection signal of the light source light transmitted through the liquid to be controlled of concn. and adjusting the concn. CONSTITUTION:The light source light from a light source 35 through a specific density filter 39 is received in the 2nd photodetector 38, whereby a reference signal is generated. On the other hand, the light source light from the light source 35 transmits through the liquid 12 to be controlled of concn. between optical fibers 34a and 34b and is received in the 1st photodetector 36. A toner supply control device 30 is controlled by way of a control circuit 42 via the differential output between the detection signal and reference signal by the photodetection of these elements 36 and 38 by a differential amplifier 41, whereby the toner concn. or the like of the developing solution or the like is controlled within a desired range. Hence, the developing soln. of always stable liquid concn. is obtained.