Efficient lighting circuit for LED assemblies

Patent metadata

Field	Value
Publication number	US-9872348-B2
Application number	US-201615161328-A
Country	US
Kind code	B2
Filing date	May 23, 2016
Priority date	May 28, 2015
Publication date	Jan 16, 2018
Grant date	Jan 16, 2018

Abstract

A lighting circuit and a method of operating a lighting circuit are described. A rectifier 14 has an input for an alternating voltage V. At least a first and a second LED assembly 20, 22 are connected to be supplied with electrical power from the rectifier 14 . The first LED assembly 20 is electrically connected to a first output 26 of the rectifier 14 and electrically connected in series with an input 36 of a switching converter circuit. The second LED assembly 22 is electrically connected to an output 48 of the switching converter circuit 44 . A control assembly 30 is connected to a tap 46 in the series connection for controlling operation of the first LED assembly 20.

First claim

The invention claimed is:

1. Lighting circuit, comprising:
a rectifier with an input for an alternating voltage, wherein said rectifier outputs a rectified voltage; and
at least a first and a second LED assembly connected to be supplied with electrical power from said rectifier,
wherein said first LED assembly is electrically connected in series with a first output of said rectifier, said first LED assembly being further electrically connected in series with an input of a switching converter circuit, and said second LED assembly is electrically connected to an output of said switching converter circuit, and
wherein a control assembly for controlling operation of said first LED assembly is connected to a tap in said series connection, the control assembly comprising a switching element controllable at least in a conducting and non-conducting state, said switching element being connected to bypass said first LED assembly in said conducting state,
wherein said switching element is operated in a nonconductive state when said rectified voltage exceeds a first threshold, thereby activating said first LED assembly,
wherein, when said rectified voltage exceeds said first threshold, a residual voltage is input to said switching converter circuit, and
wherein, when said residual voltage exceeds a second threshold, an output voltage of said switching converter circuit activates said second LED assembly.

2. Lighting circuit according to claim 1 , wherein
said switching converter circuit comprises at least a reactive element, a controllable switching element and a control circuit for controlling said controllable switching element to repeatedly alternate between a conducting and a non-conducting state.

3. Lighting circuit according to claim 1 , wherein
at least a third LED assembly is electrically connected in said series connection between said first output of said rectifier and said input of said switching converter,
and wherein a control assembly for controlling operation of said third LED assembly is connected to a tap in said series connection.

4. Lighting circuit according to claim 1 , wherein
said switching converter circuit comprises at least two input terminals,
wherein a capacitor is connected between said two input terminals.

5. Lighting circuit according to claim 4 , wherein
said capacitor is electrically connected in series at least to said first LED assembly.

6. Lighting circuit according to claim 1 , wherein
at least one of said LED assemblies comprises multiple LED elements electrically connected in series, in parallel, or in a series/parallel connection.

7. Lighting circuit according to claim 1 , wherein
a stabilizing capacitor is electrically connected in parallel with at least one of said LED assemblies.

8. Lighting circuit according to claim 1 , wherein
said second LED assembly is electrically connected in series with said first LED assembly.

9. Lighting circuit according to claim 1 , wherein
said second LED assembly is electrically connected between said first LED assembly and an input of said switching converter circuit.

10. Lighting circuit according to claim 1 , wherein
a current source is electrically connected in series to said first LED assembly.

11. Method of operating a lighting circuit, comprising:
supplying a rectifier with an alternating voltage to supply electrical power from said rectifier to at least a first and a second LED assembly, wherein said rectifier outputs a rectified voltage,
wherein said first LED assembly is electrically connected in series with a first output of said rectifier, said first LED assembly being electrically connected in series with an input of a switching converter circuit,
wherein said second LED assembly is electrically connected to an output of said switching converter circuit,
wherein a control assembly for controlling operation of said first LED assembly is connected to a tap in said series connection, the control assembly comprising a switching element controllable at least in a conducting and non-conducting state, said switching element being connected to bypass said first LED assembly in said conducting state,
wherein said switching element is operated in a nonconductive state when said rectified voltage exceeds a first threshold, thereby activating said first LED assembly,
wherein, when said rectified voltage exceeds said first threshold, a residual voltage is input to said switching converter circuit, and
wherein, when said residual voltage exceeds a second threshold, an output voltage of said switching converter circuit activates said second LED assembly.

Assignees

• Philips Lighting Holding Bv

Inventors

• Arulandu Kumar
• Linnartz Johan-Paul Marie Gerard
• De Mol Eugen Jacob
• Malyna Dmytro Viktorovych
• Kahlman Henricus Marius Joseph Maria

Classifications

• H05B45/48 Primary

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

• H05B45/37

  Converter circuits · CPC title

• Y02B20/346

  Cross-Sectional Technologies · mapped topic

• H05B33/083

  Electricity · mapped topic

• H05B33/0815 Primary

  Electricity · mapped topic