Chin Russell Chang, 696025 Starwood Dr, San Jose, CA 95120

6337800, Jan 8, 2002

Feb 29, 2000

09/516173

Chin Chang - Yorktown Heights NY

Philips Electronics North American Corporation - New York NY

H02M 545

363 37, 315209 R

A low frequency to high frequency power converter having a power feedback network from a high frequency voltage source to the low frequency input to a DC supply circuit for the high frequency voltage source. The network forms part of a feedback path which has an inductive impedance at one or more frequencies within the operational range of the high frequency source. In a fluorescent lamp ballast embodiment, feedback is from a load connection point through a path having at least an inductor and a capacitor in series. A low pass filter input to the DC supply circuit may have a shunt capacitor across the rectifier input. The feedback network may include a capacitor in series with the parallel combination of an inductor and a capacitor. In another embodiment the feedback inductor is a tapped inductor connected to the rectifier input, its two inductor portions having mutually exclusive periods of zero current flow.

6362575, Mar 26, 2002

Nov 16, 2000

09/713867

Chin Chang - Yorktown Heights NY
Theo Stommen - Veldhoven, NL

Philips Electronics North America Corporation - New York NY

H05B 3702

315224, 315291, 315307, 315244, 315312, 315209 R, 315DIG 7

A method and apparatus for regulating the lamp output voltage in a multiple (parallel) discharge lamp fixture irrespective of the number of operating lamps and based upon monitoring of the lamp filament current. A modification thereof provides constant and equal currents in the discharge lamps irrespective of the number of operating lamps.

6369525, Apr 9, 2002

Nov 21, 2000

09/717969

Chin Chang - Yorktown Heights NY
Subramanian Muthu - Tarrytown NY
Gert W. Bruning - Sleepy Hollow NY

Philips Electronics North America - New York NY

G05F 100

315300, 315302, 315312, 315362, 315278, 363 17, 363 23, 362800

A white light-emitting-diode array driver circuit with a multiple output flyback (or forward) converter with output current mode control. The circuit comprises a power supply source and a transformer. The transformer has a primary winding coupled to, and configured to receive current from, the power supply, and a plurality of secondary windings coupled to the primary winding. The circuit also comprises a plurality of light-emitting-diode arrays, wherein each light-emitting-diode array is coupled to one of the secondary windings. A main controller is coupled to a first of the light-emitting-diode arrays and is configured to control a flow of current to the primary transformer winding. The circuit also comprises a plurality of secondary controllers, each of which are coupled to another of the light-emitting-diode arrays. In addition, each of the secondary controllers are configured to control a flow of current to its corresponding light-emitting-diode array. According to one embodiment of the invention, each of the light-emitting diodes has a resistor coupled to its cathode terminal.

6373725, Apr 16, 2002

Nov 20, 2000

09/716698

Chin Chang - Yorktown Heights NY
Adan Hernandez - Naperville IL
Gert Bruning - Sleepy Hollow NY

Philips Electronics North America Corporation - New York NY

H02M 3335

363 2101, 323222, 323284

A switchable power converter includes an input section that receives an AC input voltage and rectifies the AC input voltage and a switchable converter section operative to receive the rectified AC input voltage and convert the rectified AC input voltage to an intermediate DC output voltage. The switchable converter section includes at least one configuration switch operative to switch the switchable converter section between a boost converter topology, for low input line voltages, and either a flyback or SEPIC converter circuit topology, for high input line voltages.

6376999, Apr 23, 2002

Sep 15, 2000

09/663807

Yushan Li - Ossining NY
Chin Chang - Yorktown Heights NY

Philips Electronics North America Corporation - New York NY

H05B 3702

315307, 315224, 315324, 315DIG 5

An LCD backlight inverter that comprises a power stage that includes a first power switch and a second power switch that powers one or more cold cathode fluorescent lamps. A controller generates control signals, receives an IC supply input signal having a voltage level equaling or exceeding a prescribed threshold level, and provides a steady-state internal oscillation that drives said first and second power switches. A transient prevention circuit maintains said second power switch in a nonconducting state until at least a time at which said IC supply input signal reaches said prescribed voltage threshold. Alternatively, a transient prevention circuit maintains said second power switch in a nonconducting state until at least a time at which said IC supply input signal reaches said prescribed voltage threshold, and additionally prevents the controller oscillator from generating said internally generated oscillation until at least a time at which a supply voltage to the IC reaches a threshold value.

6407935, Jun 18, 2002

May 30, 2000

09/580170

Chin Chang - Yorktown Heights NY
Gert W. Bruning - Sleepy Hollow NY

Koninklijke Philips Electronics N.V. - Eindhoven

H02J 300

363 34, 315308

A lamp ballast circuit which provides a magnetizing inductance to a lamp ballast circuit transformer. A DC voltage and current supply source energize a pair of transistors which provide an AC voltage and current. The transformer includes a primary winding that receives the AC voltage and current. At least one lamp is coupled to the transformer secondary winding via a capacitor. The circuit has an optimal magnetizing inductance such that the transformer input voltage and current are substantially in phase with each other, thereby substantially reducing or eliminating the reactive power transferred through the output transformer. In a preferred embodiment, the magnetizing inductance, L , is given as: wherein is an operating frequency, C is the capacitance of the capacitor, R is the resistance of the at least one lamp, and n is the secondary-to-primary side turns ratio of the transformer.

6429604, Aug 6, 2002

Jan 21, 2000

09/489753

Chin Chang - Yorktown Heights NY

Koninklijke Philips Electronics N.V. - Eindhoven

H05B 3700

315244, 315224, 315247, 315209 R, 315DIG 7

A ballast circuit for a single or multiple lamp parallel operation where at each lamp a condition may be controlled such that the amplitude of a resonant inductor current and an output voltage are almost constant in the steady state. The circuit consists of a half-bridge of a DC storage capacitor, a DC blocking capacitor, power transistors which alternately switch on and off and have a 50% duty ratio, and an LLC resonant converter having a resonant inductor and one or more resonant capacitors. The circuit also includes an output transformer providing galvanic isolation for a double path type power feedback scheme. The output transformer produces magnetizing inductance utilized for power feedback circuit optimization and is connected right after the resonant inductor of the half-bridge circuit.

6441558, Aug 27, 2002

Dec 7, 2000

09/732197

Subramanian Muthu - Tarrytown NY
Chin Chang - Yorktown Heights NY
Gert Bruning - Sleepy Hollow NY

Koninklijke Philips Electronics N.V. - Eindhoven

H05B 3702

315149, 315291, 315118

An LED luminary system for providing power to LED light sources to generate a desired light color comprises a power supply stage configured to provide a DC current signal. A light mixing circuit is coupled to said power supply stage and includes a plurality of LED light sources with red, green and blue colors to produce various desired lights with desired color temperatures. A controller system is coupled to the power supply stage and is configured to provide control signals to the power supply stage so as to maintain the DC current signal at a desired level for maintaining the desired light output. The controller system is further configured to estimate lumen output fractions associated with the LED light sources based on junction temperature of the LED light sources and chromaticity coordinates of the desired light to be generated at the light mixing circuit. The light mixing circuit further comprises a temperature sensor for measuring the temperature associated with the LED light sources and a light detector for measuring lumen output level of light generated by the LED light sources. Based on the temperatures measured, the controller system determines the amount of output lumen that each of the LED light sources need to generate in order to achieve the desired mixed light output, and the light detector in conjunction with a feedback loop maintains the required lumen output for each of the LED light sources.