The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 25, 1981
Filed:
Jul. 25, 1979
Alex Vinatzer, Brixen, IT;
Durst AG Fabrik Fototechnischer Apparate, Bozen, IT;
Abstract
In a circuit for the control of exposure time with photographic enlarging equipment with variable enlargement ratio, and with a device for determining light quantity, a light sensitive electric transducer is provided a fixed distance to the negative plane of the enlarging equipment. Means for generating a signal representing the enlargement ratio, in the form of a potentiometer, modifies the signal derived from the device for determining light quantity to thereby produce a signal representative of the proper change of exposure time for a selected enlargement ratio. The circuit incorporates function generators to modify the signal from the light sensitive electric transducers to allow for the correction of the failure of the reciprocity law. The light sensitive electric transducer is in the form of a photodiode, and the signal derived therefrom as a result of determining light quantity produces a charge on a capacitor which develops a signal, in one embodiment, that is compared in a comparator with the potentiometer signal.