LED light source

Patent metadata

Field	Value
Publication number	US-9655176-B2
Application number	US-201314384047-A
Country	US
Kind code	B2
Filing date	Feb 22, 2013
Priority date	Mar 9, 2012
Publication date	May 16, 2017
Grant date	May 16, 2017

Abstract

The invention relates to a LED light source comprising: input terminals (K 1 , K 2 ) for connection to a mains voltage supply source, a rectifier (RB) coupled to the input terminals for rectifying the mains supply voltage supplied by the mains supply voltage source and comprising rectifier output terminals, a DC-DC converter (CONV) for generating a DC current out of the rectified mains supply voltage, comprising converter input terminals connected to the rectifier output terminals and comprising a first converter output terminal (A) and a second converter output terminal (B), —a LED load (LL) with an anode coupled to the first converter output terminal via a current control element (D 5 ) for blocking a current flowing from the anode of the LED load to the first converter output terminal, and with a cathode coupled to the second converter output terminal via a first controllable switch (M 1 ) having a control electrode coupled to first control circuitry for rendering the controllable switch non-conductive in case the LED light source is in standby mode.

First claim

The invention claimed is:

1. A light emitting diode (LED) light source, comprising:
input terminals for connection to a mains voltage supply source to receive a mains supply voltage,
a rectifier coupled to the input terminals for rectifying the mains supply voltage supplied by the mains supply voltage source and comprising rectifier output terminals,
a DC-DC converter for generating a DC current out of the rectified mains supply voltage, comprising converter input terminals connected to the rectifier output terminals and comprising a first converter output terminal and a second converter output terminal,
a LED load with an anode coupled to the first converter output terminal via a current control element for blocking a current flowing from the anode of the LED load to the first converter output terminal, and with a cathode coupled to the second converter output terminal via a first controllable switch having a control electrode coupled to first control circuitry for rendering the controllable switch non-conductive in case the LED light source is in standby mode,
wherein the first control circuitry comprises a voltage divider comprising a series arrangement of a first resistor and a second resistor connecting the first converter output terminal to the second converter output terminal and the control electrode of the controllable switch is coupled to a terminal between the first resistor and the second resistor.

2. The LED light source of claim 1 , wherein the current control element is a diode.

3. The LED light source of claim 1 , wherein the current control element is a further controllable switch having a control electrode coupled to further control circuitry for rendering the further controllable switch non-conductive in case the LED light source is in standby mode.

4. The LED light source of claim 3 , wherein the further controllable switch comprises a FET.

5. The LED light source of claim 3 , wherein the first controllable switch and the current control element each comprise a relay.

6. The LED light source of claim 3 , wherein the standby mode is entered by stopping the operation of the DC-DC converter, and wherein the further control circuitry for rendering the further controllable switch non-conductive in case the LED light source is in standby mode, is comprised in a converter control circuit comprised in the DC-DC converter and the control electrode of the further controllable switch is coupled to a second output terminal of the converter control circuit.

7. The LED light source of claim 1 , wherein the first controllable switch comprises a FET.

8. The LED light source of claim 1 , wherein the DC-DC converter comprises a transformer equipped with a primary winding and a secondary winding and a capacitor is coupled between the primary winding and the secondary winding.

9. The LED light source of claim 1 , wherein the first control circuitry further comprises a Zener diode connected between the control electrode of the first controllable switch and the second converter output terminal.

10. The LED light source of claim 1 , wherein the mains voltage supply source has a first terminal, a neutral terminal, and a protective earth terminal connected to the neutral terminal, wherein the input terminals of the LED light source include a first input terminal connected to the first terminal of the mains voltage supply source and a second input terminal connected to the neutral terminal of the mains voltage supply source, the LED light source further having a parasitic capacitance between the LED load and the protective earth terminal of the mains voltage supply source.

11. A device, comprising:
input terminals for connection to a mains voltage supply source to receive a mains supply voltage,
a rectifier coupled to the input terminals of the device and having rectifier output terminals, the rectifier being configured to rectify the mains supply voltage and to output a rectified mains supply voltage via the rectifier output terminals;
a DC-DC converter having converter input terminals connected to the rectifier output terminals to receive the rectified mains supply voltage, and having a first converter output terminal and a second converter output terminal configured to supply a DC current in response to the rectified mains supply voltage;
a light emitting diode (LED) load with an anode and a cathode;
a current control element having a first terminal connected to the first converter output terminal and a second terminal connected to the anode of the LED load to the first converter output terminal, the current control element being configured to allow the DC current to flow from the first converter output terminal to the anode of the LED load and to block a leakage current from flowing from the anode of the LED load to the first converter output terminal;
a controllable switch having a first terminal connected to the cathode of the LED load and a second terminal connected to the second converter output terminal, and further having a control electrode for selectively turning on the controllable switch to allow the DC current to flow from the cathode of the LED load to the second converter output terminal through the controllable switch, and turning off the controllable switch to prevent a parasitic current from flowing through the LED load via the controllable switch when the device is in a standby mode wherein the DC current is not supply the DC-DC converter; and
a resistor voltage divider comprising:
a first resistor connected between the first converter output terminal and control electrode of the controllable switch, and
a second resistor connected between the control electrode of the controllable switch and the second converter output terminal.

12. The device of claim 11 , further comprising a Zener diode connected between the control electrode of the first controllable switch and the second converter output terminal.

13. The device of claim 11 , wherein the device is a luminaire, and wherein the mains voltage supply source has a first terminal, a neutral terminal, and a protective earth terminal connected to the neutral terminal, wherein the input terminals of the LED light source include a first terminal connected to the first terminal of the mains voltage supply source and a second terminal connected to the neutral terminal of the mains voltage supply source, wherein the luminaire is also directly connected to the protective earth terminal, the luminaire further having a parasitic capacitance between the LED load and the protective earth terminal of the mains voltage supply source.

14. The device of claim 11 , wherein the DC-DC converter includes a converter control circuit having an output terminal, and wherein the current control element comprises a further controllable switch, the further controllable switch having a control electrode connected to the output terminal of the converter control circuit for rendering the further controllable switch non-conductive in case the device is in the standby mode.

15. The device of claim 11 , wherein the controllable switch is a field effect transistor (FET), wherein the control electrode is a gate of the FET, and wherein the first resistor is connected directly to the first converter output terminal and also connected directly to the gate of the FET.

Assignees

• Philips Lighting Holding Bv

Inventors

• Van Der Veen Geert Willem
• Cornelissen Wilhelmus Josephus

Classifications

• H05B45/48

  having LEDs organised in strings and incorporating parallel shunting devices · CPC title

• H05B45/44

  with an active control inside an LED matrix · CPC title

• H05B45/37 Primary

  Converter circuits · CPC title

• H05B45/59

  for reducing or suppressing flicker or glow effects · CPC title

• H05B33/083

  Electricity · mapped topic