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. 10, 2012
Filed:
Oct. 13, 2009
Nanu Brates, Winchester, MA (US);
Bhavinkumar Shah, Burlimgton, MA (US);
Yiyoung Tony Sun, Beverly, MA (US);
Nanu Brates, Winchester, MA (US);
Bhavinkumar Shah, Burlimgton, MA (US);
Yiyoung Tony Sun, Beverly, MA (US);
Panasonic Corporation, Osaka, JP;
Abstract
An apparatus and method thereof for igniting and operating a high intensity discharge (HID) lamp during an in service life, and powering down the lamp when an end-of-life (EOL) lamp condition is detected. The apparatus and method defines a series of thresholds of lamp voltage asymmetry, or rectification thresholds, and monitors the lamp rectification from ignition through normal operation. The detection scheme is masked off for a predetermined period of time when the lamp is initially started. Thereafter, the rectification threshold of the lamp voltage asymmetry is gradually reduced over time, until a defined minimum rectification threshold level is reached and maintained. The method continuously monitors the lamp voltage and records whenever the lamp voltage asymmetry is higher than the rectification threshold level at any lamp voltage cycle. An EOL lamp condition is determined to exist when a certain number of high asymmetrical cycles occurs in selected total number of lamp voltage cycles during a rolling measurement window.