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:
Apr. 11, 1978
Filed:
Jul. 24, 1975
Robert C Mau, deceased, late of Chicago, IL (US);
Erwin E Figge, Des Plaines, IL (US);
Bell & Howell Company, Chicago, IL (US);
Abstract
The disclosure relates to a fade circuit for a motion picture camera of the type which includes an automatic exposure control. The fade circuit includes a light emitting diode which illuminates the light sensitive device of the automatic exposure control to augment the ambient light levels normally received by the light sensitive device. The intensity of the light emitted by the light emitting diode is controlled by a variable current source which provides the light emitting diode with continuously increasing or decreasing current for increasing or decreasing the intensity of the light from the light emitting diode. Fade-in is obtained as the light intensity of the light emitting diode is gradually decreased from an initial intensity sufficient to close the diaphragm opening to zero intensity to allow the diaphram to assume an opened condition corresponding to ambient light levels. Fade-out is obtained as the light intensity of the light emitting diode is gradually increased from an initial zero intensity which causes the diaphragm to be in an open condition corresponding to ambient light levels to an intensity sufficient to close the diaphragm opening.