Koninklijke Philips Corporation N.v.

Philips Electronics North America Corporation

Subramanian Muthu

Chin Chang

Gert W Bruning

James M Gaines

Frank J Schuurmans

Arjen Gerben Van Der Sijde

Bernd Clauberg

Oscar Jan Deurloo

Lukas Leyten

Seymour Perkins, Iii

Roy Hendrik Anna Maria Van Zundert

Jeffrey Lord

Wouter Edgard Koen Broeckx

Gerlach Corne Pieter Maria Emmen

Schuurmans Frank J P

An electronic ballast with remote capacitor placement includes a first housing (); a second housing (); an AC/DC converter (); a DC bus () operably connected to the AC/DC converter (); a lamp driver () operably connected to the DC bus (); and a storage capacitor () connected to the DC bus () with capacitor wires (). The AC/DC converter (), the DC bus (), and the lamp driver () are disposed in the first housing (); the storage capacitor () is disposed in the second housing (); and the first housing () is thermally isolated and physically separated from the second housing ().

Electronic blast with remote capacitor placement

A method of electronic ballast protection including providing an electronic ballast having an AC/DC converterwith an electronic ballast input and a mains voltage connectionconnectable to a mains voltage, an inverteroperably connected to the AC/DC converterand having an electronic ballast outputconnectable to a lamp, a control circuitcontrolling the inverter, and a low voltage power supplyproviding low voltage power to the control circuit; supplying power to the low voltage power supplyfrom the electronic ballast input when the mains voltage connectionis wired to mains voltage; and disconnecting the power to the low voltage power supplywhen the electronic ballast outputis wired to the mains voltage

Electronic ballast protection

Apparatus and method for backlighting an electronic display with LEDs to control luminosity, radiometric power, and color levels by means of feedback control through a microprocessor, thereby maintaining white backlight at substantially constant levels, which can be chosen by an operator.

LED-based white-light backlighting for electronic displays

A white light is provided for backlighting a liquid crystal display by directing red green and blue light into the first end of a color mixing optical fiber, mixing the red green and blue light in the color mixing fiber to produce white light, and conducting the white light out of the second end of the color mixing fiber to the liquid crystal display. The color mixing optical fiber and sources for generating the red green and blue light may be located remotely from the liquid crystal display, and the white light produced in the color mixing optical fiber coupled to the liquid crystal display by coupling optical fibers, thus simplifying and facilitating construction and operation of the backlighting system, and allowing for more convenient removal of heat remotely from the liquid crystal display.

White light source for LCD backlight

An LED array is controlled by determining a constant relating the peak light output of an LED to the peak driving current of a PWM pulse driving the LED, and multiplying the average current of the PWM pulse by the constant to obtain a value of average light output for the LED. The constant may be determined by simultaneously measuring peak light output of the LED and peak current of a PWM pulse driving the LED. The constant is then calculated by dividing the peak light output by the peak current of the PWM pulse. By making the simultaneous measurements at a time during the duration of the PWM pulse where the pulse has reached its full magnitude, rise and fall times of the pulse do not affect the measurements. The average current of the PWM pulse may be determined by a variety of methods including integrating current in the PWM pulse over time, or passing the PWM current through a low pass filter configured for providing an average value of PWM current. Determining average current in this manner further reduces the effect of rise and fall time on determining the average light output of the LED.

Average light sensing for PWM control of RGB LED based white light luminaries

A light output control system for implementing a method for sensing the tri-stimulus values for controlling a light output illuminated from an LED based luminary is disclosed. The system comprises one or more filter/photo diode sensors for sensing a first set of tri-stimulus values of the light output and providing signals indicative thereof. The signals are utilized in a transformation matrix whereby a second set of tri-stimulus values is obtained. The system controls the light output as a function of the second set of tri-stimulus values.

Method and system for controlling a light source

A device for controlling and adjusting a display light for a retail display system comprising a computer associated with plural light sources for adjusting the light sources to optimally display particular products. The light sources are adjusted based upon a prestored table specifying optimal lighting conditions for each of plural products, and a feedback loop that feeds back actual lighting conditions.

RGB LED based light driver using microprocessor controlled AC distributed power system

A method and a system for controlling a RBG based LED luminary which tracks the tristimulus values of both feedback and reference whereby the forward currents driving the LED luminary are adjusted in accordance with the errors between the feed tristimulus values and the reference tristimulus values until the errors are zero.

Controlling method and system for RGB based LED luminary

The combined light output (chromaticity) of a white light emitting LED luminaire is electronically controlled based on measurements by a single photodiode arranged to measure the light outputs of at least a plurality of the LEDs in the array. This is accomplished by measuring the light output of the LEDs in each color separately in a sequence of time pulses. For an array of red, green, and blue LEDs there are three time pulses in a measuring sequence. During each time pulse, the current for the color being measured is turned off. The response time of a typical photodiode is extremely short, so the measuring sequence can be performed in a sufficiently short time that an-observer will not detect it (e.g. 10 ms). Measured light outputs for the colors are compared to desired outputs, which may be set by user controls, and changes to the power supply for the color blocks are made as necessary. Chromaticity is thus automatically controlled without regard to the factors which may cause it to change. The user inputs permit varying the desired chromaticity to either warm white (more red output) or cool white (more blue output).

LED luminaire with electrically adjusted color balance using photodetector

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.

White LED luminary light control system

The present invention describes a method and luminaire for driving an array of LEDs with at least one LED in each of a plurality of colors in a luminaire. This method controls the light output and color of the LEDs by measuring color coordinates for each LED light source for different temperatures, storing the expressions of the color coordinates as a function of the temperatures, deriving equations for the color coordinates as a function of temperature, calculating the color coordinates and lumen output fractions on-line, and controlling the light output and color of said LEDs based upon the calculated color coordinates and lumen output fractions.

Effective modeling of CIE xy coordinates for a plurality of LEDs for white LED light control

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. An output signal of each resistor is transmitted to the respective controller and is employed to determine the appropriate current flow to the light-emitting-diode array. The circuit may be configured as either a flyback converter, wherein the primary transformer winding is wound in the opposite direction of the secondary transformer windings, or as a forward converter, wherein the primary transformer winding is wound in the same direction as secondary transformer windings.

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Ossining, NY, United States of America

Subramanian Muthu