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:
Jul. 21, 1992
Filed:
Sep. 30, 1991
Stefan A Siegel, Fogelsville, PA (US);
AT&T Bell Laboratories, Murray Hill, NJ (US);
Abstract
An LED pulse shaping circuit is disclosed which is capable of providing improved rise time (using current peaking) and fall time (using charge extraction). The pulse shaping circuit consists of a conventional differential current switch coupled to a pair of switching elements and resistance elements. A first switching element is activated at the beginning of a pulse to provide for an initially increased drive current to the LED, the value of a first resistance element used to determined the level of the increased drive current. The current peaking thus results in decreasing the rise time of the LED. The remaining switching element and resistance are utilized, in conjunction with the differential current switch, to provide a reverse current flow through the LED at the end of the pulse. The charge extraction thus results in decreasing the fall time of the LED.