GB1469004A - Method of stabilizing developer activity in an automatic film processor - Google Patents

Abstract

1469004 Film processing LOGETRONICS Inc 25 Nov 1974 50980/74 Heading G2X In a film processor comprising developing, fixing and washing tanks through which the exposed film is transported a mixing tank 12 is provided connected by an outflow line to developer tank 1. Control means 7 operate valve 8 to feed fluid from supply 5 to replenish the developer, is activated by a predevelopment signal generating means 14, e.g. micro-switch, infrared sensing system or manually operated device, 14 to feed an initial increment of replenisher prior to processing and by a postdevelopment sensor downstream of the fixing tank, responsive to image density of processed film to feed a further increment of replenisher. The processer also includes an inlet flow line for supplying at least a portion of such replenisher increments to the mixing tank for mixing with developer solution already in the tank and the mixed solution is then supplied by an outflow line to the developing tank. The mixing tank, as shown, may be connected in parallel with at least a portion of the developing tank for increasing the effective volume of developer in the processor. The output signals provided by sensor 14 is coupled to unit 7 to effect initial replenishment. Output from sensors 14 and 15 are also coupled to a comparison unit 16, the output from which is combined in adder circuit 18 with a signal from circuit 17, dependent on lowering of development activity due to oxidation. The output from 18 is also coupled to solenoid valve 8 via control unit 7 to effect additional replenishment, or may be fed to a storage unit for later utilization if valve 8 is already open.