Koninklijke Philips Corporation N.v.

Zenith Electronics Corporation

Koninklijke Philips Electronics N.v.

Timothy B Moss

Bernd Clauberg

James M Gaines

Eric J Kille

Mubasher Ahmad

A lighting unit includes at least two channels of light sources, and a driver for the light sources. The driver includes a DC/DC converter and a control arrangement for controlling the current supplied to at least one of the two channels in response to a control signal produced by the DC/DC converter. Beneficially, a feedback loop controls a switching device in the DC/DC converter to maintain the light level produced by the light sources at a desired level regardless of changes in the supply voltage arid the load.

Multichannel lighting unit and driver for supplying current to light sources in multichannel lighting unit

A lighting unit includes at least two channels of light sources, and a driver for the light sources. The driver includes a DC/DC converter and a control arrangement for controlling the current supplied to at least one of the two channels in response to a control signal produced by the DC/DC converter. Beneficially, a feedback loop controls a switching device in the DC/DC converter to maintain the light level produced by the light sources at a desired level regardless of changes in the supply voltage and the load.

Methods and apparatus for adjusting the color or color temperature of combined light emitted by one or more LEDs () driven by a single switching regulator circuit (). Properties of the light output are changed by intentionally varying a source voltage () provided as an input to the regulator circuit (). The connection of different colored LEDs in various branches () of the switching regulator circuit () facilitates adjustment of the respective drive currents provided to the LEDs, and hence the color or color temperature of the resulting combined light, merely by adjusting the level of the source voltage of the regulator circuit.

Methods and apparatus for controlling multiple light sources via a single regulator circuit to provide variable color and/or color temperature light

A lighting fixture (-) mechanically encloses a LED module (), which includes at least one LED () and can further include a LED driver () in electrical communication with the LED(s) () to operably provide a LED drive signal to the at least one LED (), a thermal management system () in thermal communication with the LED(s) () and the lighting fixture (-) to facilitate a heat transfer from the LED(s) () to the lighting fixture (-), and/or a beam shaper () in optical communication with the LED(s) () to modify an illumination profile of a radiation beam emitted by the LED(s) ().

LED lighting fixtures

A self-oscillating circuit particularly adapted for driving the deflection yoke of a cathode ray tube (CRT) or a high voltage pulse transformer is disclosed. The circuit includes an NPN transistor, to the collector of which is coupled a direct voltage source and a first inductance and to the base of which is coupled a second, grounded inductance. Following transistor turn-on, the collector current ramps up in storing energy in the first inductance. With the transistor base drive removed, a voltage spike appears on the transistor's collector to which is coupled a grounded capacitor. The LC network comprised of the first inductance and the grounded capacitance attempts to resonate, with the collector voltage clamped by the transistor collector-base junction. The energy stored in the first inductance flows via the grounded voltage source and the collector-base junction of the forward biased transistor into the second inductance until the energy stored in the first inductance has been reduced to the point where the transistor's collector-base junction is no longer forward biased. Continued current flow through the second inductance to the transistor's base turns the transistor on, causing current to be reversed in the first inductance in repeating the cycle as energy is again stored therein. Transistor base drive stops when the energy in the second inductance is depleted. The values of a resistance in series with the second inductance and the aforementioned capacitance determine the circuit's oscillatory period.

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Chicago, IL, United States of America

Timothy B Moss