Pako Corporation

Theodore A Melander

Ralph L Charnley

An automatic anti-oxidation fluid replenisher system for processors of photosensitive material has an improved, digital electronic control system. The control system includes a digital binary counter which is counted down if use-related chemical replenishment is not occurring in the processor, and is counted up (generally at a different rate) if use-related chemical replenishment is occurring in the processor. When the counter reaches a predetermined value (e.g. zero), a detection circuit triggers anti-oxidation replenishment and resets the counter to its original value for further operation. A special circuit protects against counter roll-over should the counter reach its maximum capacity due to frequent chemical replenishment activity.

Anti-oxidation fluid replenisher control system for processor of

A system having two heaters, such as a photographic processor with a solution heater and a dryer heater, has proportional controllers for each of the heaters. A priority control co-ordinates operation of the two controllers to give full priority to one of the two heaters during warm up, and a reduced percentage for running conditions. The other heater is allowed to share the remaining available input power.

Duty cycle shared proportional temperature control

A replenisher system for photographic processors includes an automatic calibration system. A film sensor senses when film approaches the density sensor (and guarantees that the sensor is clear), and the automatic calibration system calibrates the density sensor (or other film parameter sensor) of the replenisher system prior to the film reaching the density sensor. The automatic calibration is performed each time a strip of film enters the processor, and reaches the density sensor, thereby assuring that drift and other variations in density sensor output unrelated to the film density are eliminated. In addition, the automatic calibration system provides a data valid signal after the density sensor has been calibrated to allow the replenisher control to accept the output signals from the density sensor and control the supply of replenisher fluid to the processor only for a limited time interval after calibration (i.e. while film is actually present in the density sensor).

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Minneapolis, MN, United States of America

Theodore A Melander