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. 16, 2013
Filed:
Jan. 22, 2010
Yoshifumi Kuroki, Osaka, JP;
Shunsuke Shibata, Hyogo, JP;
Yoshifumi Kuroki, Osaka, JP;
Shunsuke Shibata, Hyogo, JP;
Panasonic Corporation, Osaka, JP;
Abstract
An illumination device includes one or more LED's and a power supply configured to convert energy from a commercial AC power source and drive said LED's. The power supply includes a rectifier circuit, a phase detection circuit receiving an output voltage from the rectifier circuit and a switching element. A circuit includes the one or more LED's, an inductive element and a diode, and is coupled on a first end to the rectifier circuit and coupled on a second end to ground through the switching element. A current sensor is positioned to detect a current flowing to the light-emitting diode. A control circuit is coupled to receive the detected current and the detected phase of the rectified output voltage, and further coupled to the switching element and configured to generate a PWM signal for driving the switching element at a frequency higher than a commercial AC frequency. The PWM signal has a pulse width determined in accordance with one or more of a feedback control based on a current detected by the current sensor and a feed-forward control based on a phase of the pulsating voltage detected by the phase detection circuit.