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:
Oct. 01, 1991
Filed:
May. 15, 1990
Meerten Luursema, Eindhoven, NL;
U.S. Philips Corporation, New York, NY (US);
Abstract
A switching device for operating a lamp (4) by means of a pulse-shaped voltage (V1) in which switching means (3) generate the pulse-shaped voltage (V1) from an input voltage. The amplitude of the pulse-shaped voltage (V1) is proportional to the input voltage. A pulse width modulator (2) supplies control pulses to the switching means and a first auxiliary circuit (S1) generates a first signal that is derived from the pulse-shaped voltage (V1). The first signal is proportional to the average value of the pulse-shaped voltage. A control device (1) makes the first signal substantially equal to a second signal by supplying a control signal to the pulse width modulator. A second auxiliary circuit (S2) generates the second signal, which is inversely proportional to the input voltage, whereby the switching device is able to operate the lamp at a voltage with a constant effective value.