Accurate Control of Chemical Replenishment in Automatic Processing Equipment by Means of Fiber Optics Film Scanning.

Graphic arts film processing is now a highly mechanized and controlled operation except in the area of chemical replenishment, where manually-aided semi-automatic functions are still routine. The complexity of the replenishment control problem results from the interrelationships existing between a variety of variables, each of which can influence the characteristics of the processed image to some degree. After studying the features and deficiencies of prior techniques, it was decided to adopt an entirely different approach based upon transmission measurement by means of a fiber optics scanner of the total amount of developed silver present in each processed film, and the use of this information to govern replenishment flow. This open-loop control technique has been shown to provide excellent performance in the field, and helps to pave the way for additional control and automation in other stages of the reproduction process.