SWITCHING DEVICE FOR DRIVING LED ARRAY BY PULSE-SHAPED CURRENT MODULATION

• US 20090072761A1
• Filed: 11/05/2008
• Published: 03/19/2009
• Est. Priority Date: 02/14/2002
• Status: Abandoned Application

• Current Assignee: Philips Lighting BV (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: WESSELS, JOHANNES HENDRIK
• Application Number:
  US12/265,354
• Publication Number:
  US 20090072761A1
• Time in Patent Office: Days
• US Class Current: 315/294
• CPC Class Codes: H05B 45/14 using electrical feedback from LEDs or from LED modules
• CPC Class Codes: H05B 45/305 Frequency-control circuits
• CPC Class Codes: H05B 45/325 Pulse-width modulation [PWM]
• CPC Class Codes: H05B 45/33 Pulse-amplitude modulation [PAM]
• CPC Class Codes: H05B 45/335 Pulse-frequency modulation [PFM]
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

A circuit drives an LED array and controls the brightness of the LED array by regulating the current flowing through the array. The LED array is driven by a pulse-shaped current of which the mean value is regulated with at least one or two of the following types of modulation: frequency modulation, pulse-width modulation, and amplitude modulation.

Claims

1. A switching device for driving an LED array, the switching device comprising a drive generator configured to modulate a mean strength of a current provided to the LED array by a first modulation type, a second modulation type, and a third modulation type.

2. The switching device of claim 1, wherein the first modulation type is pulse-width modulation, the second modulation type is amplitude modulation, and the third modulation type is frequency modulation.

3. The switching device of claim 1, wherein the first modulation type is configured to reduce the mean strength from Inom to 0.05 Inom, the second modulation type is configured to reduce the mean strength to less than 0.05 Inom, and the third modulation type is configured to reduce the mean strength to 0.05*10⁻

3 Inom.

4. The switching device of claim 3, wherein the first modulation type is pulse-width modulation, the second modulation type is amplitude modulation, and the third modulation type is frequency modulation.

5. A switching device for driving an LED array, wherein the switching device comprises a drive generator configured to provide a current having a mean strength which is reducible from Inom to 0.05*10⁻

3 Inom using three different types of modulation.

6. The switching device of claim 5, wherein the three different types of modulation include pulse-width modulation, amplitude modulation, and frequency modulation.

7. The switching device of claim 6, wherein the pulse-width modulation is configured to reduce the mean strength from Inom to 0.05 Inom, the amplitude modulation is configured to reduce the mean strength to less than 0.05 Inom, and the frequency modulation is configured to reduce the mean strength to 0.05*10⁻

3 Inom.