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. 22, 2008
Filed:
Jan. 09, 2007
Yuji Kajita, Chita-gun, JP;
Yuji Kajita, Chita-gun, JP;
DENSO Corporation, Kariya, JP;
Abstract
A LED-based lamp apparatus includes a LED unit having multiple LEDs connected in series, a step-up circuit for stepping up a power supply voltage by a switching action of a switching element to supply an electric current to the LED unit, a sensing element for measuring a value of the current, and a controlling element connected in series with the LED unit to control the current based on the measured current value. When some of the LEDs of the LED unit are broken and short-circuited due to, for example, long-term use, the current increases instantaneously and an overcurrent condition occurs. In this case, the controlling element limits the current immediately to correct the overcurrent condition. Thus, the controlling element prevents the overcurrent condition from causing a secondary failure to normal LEDs of the LED unit.