Invention Grant
- Patent Title: LED light source
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Application No.: US14124733Application Date: 2012-06-04
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Publication No.: US09357607B2Publication Date: 2016-05-31
- Inventor: Henricus Marius Joseph Maria Kahlman , Ralph Kurt
- Applicant: Henricus Marius Joseph Maria Kahlman , Ralph Kurt
- Applicant Address: NL Eindhoven
- Assignee: KONINKLIJKE PHILIPS N.V.
- Current Assignee: KONINKLIJKE PHILIPS N.V.
- Current Assignee Address: NL Eindhoven
- Priority: EP11169498 20110610
- International Application: PCT/IB2012/052790 WO 20120604
- International Announcement: WO2012/168844 WO 20121213
- Main IPC: H05B37/04
- IPC: H05B37/04 ; H05B33/08

Abstract:
A LED light source comprises—a full bridge rectifier equipped with a first input terminal and a second input terminal for coupling to output terminals of the phase cut dimmer, —a series arrangement comprising N LED loads, a first and second end of said series arrangement being coupled to a first output terminal and a second output terminal of the full bridge rectifier respectively, —control means for during a period of the rectified AC supply voltage subsequently making the LED loads comprised in the first series arrangement carry a current, one by one and in dependency of the momentary amplitude of the rectified AC supply voltage when the momentary amplitude increases and for subsequently making the LED loads stop carrying a current, one by one, and in dependency of the momentary amplitude of the rectified AC supply voltage when the momentary amplitude decreases, said control means controlling the current through the LED loads at zero when the output voltage of the phase cut dimmer equals zero and controlling the current through the LED loads at a value that is independent from the phase angle of the phase cut dimmer when the output voltage of the phase cut dimmer differs from zero Volt. In order to make the LED light source compatible with a phase cut dimmer, the LED light source is further equipped with—a switchable bleeder current source coupled between the first and second output terminal of the full bridge rectifier, —a latch coupled between the first and second output terminals of the full rectifier bridge and comprising a series arrangement of a resistor and a capacitor to prevent the current through the dimmer from crossing zero after a leading edge generated by the phase cut dimmer, in case the phase cut dimmer is a leading edge phase cut dimmer, —a unidirectional element arranged in series with the capacitor for preventing discharging of the capacitor via the LED loads or the adjustable bleeder current source, and—a clamp circuit coupled to the capacitor and comprising a current source for discharging the capacitor and providing a low ohmic path for the dimmer current when the dimmer is off.
Public/Granted literature
- US20140103823A1 LED LIGHT SOURCE Public/Granted day:2014-04-17
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