Automatic density measurement calibration for photographic replenishment system

摘要

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).