Durst Phototechnik Gmbh

Alex Vinatzer

Verner Delueg

Florian Vikoler

According to a process for regulating the amount of copying light in a closed control loop of a photographic color photocopier equipped with color filters, the copying light influenced by the color filters is selectively measured in the primary colors, red, green and blue. A deviation resulting from the comparison of the real values with predeterminable set values is subdivided into a color deviation and a brightness deviation. The color deviation is compensated by regulating the color filters, whereas the brightness deviation is converted into a correction factor for the lighting time, so that for each primary color the product of the light intensity real value by the effective lighting time is constant and identical to the product of the light intensity set value by the lighting time set value.

Method and apparatus for regulation of the amount of printing light in

A method for determining the exposure time in photographic copying includes measuring the light intensity at different measuring points of the projected picture of the original to be copied for an initial copying light intensity, and forming a mean value of the light intensity values measured at such points; the exposure time for a current copying light intensity is determined by modifying the aforementioned mean value with a proportional action factor corresponding to the ratio of the light intensity value measured at a selected one of the measuring points for the current copying light intensity relative to the light intensity value measured at the same point for the initial copying light intensity. An apparatus for determining the exposure time in accordance with such method includes a microprocessor which determines the ratio of the aforementioned light intensity value measured at the selected measuring point for the current copying light intensity relative to the value measured at the same point for the initial copying light intensity; the microprocessor determines the exposure time as a result of the aforementioned mean value as modified by the aforementioned ratio.

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Brixen/Milland, Italy

Alex Vinatzer