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:
Feb. 08, 1977
Filed:
Jul. 15, 1975
AGFA-Gevaert, A.G., Leverkusen, DT;
Abstract
A light-sensitive element is connected to a capacitor to vary the charging rate of the capacitor in accordance with the light falling on the light-sensitive element. The emitter-collector circuit of a switching transistor is connected in series with the light-sensitive element. The base of the transistor is pulsed by an astable multivibrator which furnishes a pulse sequence having a pulse repetition rate which exceeds the reciprocal of the smallest exposure time. The pulses in the pulse sequence have a pulse width determined by the selected one of a plurality of resistors. The selector switch inserting the selected one of the resistors into the astable multivibrator circuit is coupled to selector means which select one of a plurality of exposure factors as for example the aperture size. The electronic switch is conductive, permitting charging of the capacitor only during the pulse duration. The charging rate of the capacitor can therefore be adapted to the particular aperture size, film sensitivity, etc. without changing the capacitance of the capacitor or covering a portion of the light-sensitive element.