Automatic colour printer exposure control device - with light output being negative logarithmically converted, integrated and balanced to predetermined constant value

摘要

A system for control of the exposure time in an automatic colour printer device in which an incremental control is operated, has the quantity of light (I) transmitted by the colour negative measured and converted into an output signal relating to the transmissivity density of the negative. This signal is then converted to a logarithmic value and then into a value suitable for the incremental control unit. This is of an experimental form and is subsequently integrated and equilibrated to a predetermined constant value. The exposure time is determined when the integrated value and constant value coincide.