Lighting systems

• US 8,242,711 B2
• Filed: 03/31/2008
• Issued: 08/14/2012
• Est. Priority Date: 03/30/2007
• Status: Active Grant

• Current Assignee: ADP Corporate Limited
• Original Assignee: Hold IP Limited
• Inventors: Pollock, Charles, Pollock, Helen, Summerland, David Thomas
• Primary Examiner(s): Owens, Douglas W
• Assistant Examiner(s): A, Minh D
• Application Number:
  US12/450,568
• Publication Number:
  US 20100141169A1
• Time in Patent Office: 1,597 Days
• Field of Search: 315/177, 315/178, 315/185.R, 315/200.R, 315/209.R, 315/246, 315/247, 315/291, 315/307, 315/308, 315/312
• US Class Current: 315/307
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/355 Power factor correction [PFC]; Reactive power compensation
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

A power adaptor (20) for a lighting unit (50) having a solid state light source (50a,50b,50c) is disclosed. The power adaptor (20) comprises an input (22) for connection to a mains power supply, a power transfer module (40a,40b,40c,140a) that is coupled to the input (22) and provides an output suitable for driving the solid state light source (50a,50b,50c), and a controller (30) that receives a voltage signal from the input (22) and is able to deliver a control signal to the power transfer module (40a,40b,40c,140a) for reducing the power drawn from the input (22). The power adaptor (20) draws current from the input (22) as a function of the voltage at the input (22) in order that the power adaptor (20) appears as a variable resistor to the mains supply.

Claims

1. A power adaptor for a lighting unit having a solid state light source, the power adaptor comprising:

an input for connection to a mains power supply,

a power transfer module that is coupled to the input and provides an output suitable for driving the solid state light source, and

a controller able to deliver a control signal to the power transfer module,

wherein the power transfer module further comprises an LCL series-parallel resonant circuit, and

wherein the power adaptor draws current from the input as a function of the voltage at the input,

such that the intensity of light output from the solid state light source is controllable by an external power reducing device.

2. A power adaptor as claimed in claim 1, wherein the power adaptor is substantially free of bulk storage capacitance between the input of the power adaptor and the power transfer module.

3. A power adaptor as claimed in claim 1, wherein the power adaptor draws current from the input as a function of voltage at the input in order that the power adaptor appears as a resistive load to the mains supply.

4. A power adaptor as claimed in claim 3, wherein the controller is able to deliver a control signal to the power transfer module, such that the power adaptor appears as a variable resistor to the mains supply.

5. A power adaptor as claimed in claim 4, wherein the controller is able to deliver a control signal to the power transfer module for reducing the power drawn from the input.

6. A power adaptor as claimed in claim 1, wherein the controller is able to deliver a control signal to the power transfer module for reducing the power drawn from the input, such that the intensity of light output from the solid state light source can be controlled by a combination of an external power reducing device and the controller.

7. A power adaptor as claimed in claim 6, wherein the controller is adapted to cause a reduction of the power drawn from the input of the power adaptor when a maximum amount of power is available, and then lessen that reduction as the amount of power available falls, thereby causing the solid state light source to follow a non-linear dimming curve.

8. A power adaptor as claimed in claim 1, wherein the solid state light source is provided with a predetermined average power.

9. A power adaptor as claimed in claim 8, wherein the predetermined average power provided to the solid state light source is substantially equal to the average power drawn at the input of the power adaptor.

10. A power adaptor as claimed in claim 9, wherein the intensity of the light output from the solid state light source inherently reduces as the power drawn from the input reduces, and hence the power adaptor does not regulate a constant output to the solid state light source.

11. A power adaptor as claimed in claim 1, wherein the power transfer module is adapted to maintain the current drawn from the input at an increased value than is required for maximum light output of the associated solid state light source, when a maximum amount of power is available from the input of the power adaptor, which is then in turn reduced by the controller to provide only the power required for maximum output and no more.

12. A power adaptor as claimed in claim 11, wherein the controller is adapted to vary the reference signal provided to the power transfer module, as an external power reducing device lowers the available input power, so that the average power of the output stays equal to the power required by the solid state light source for maximum brightness, until the power available from the input of the power adaptor is reduced below a threshold at which it equals the power required by the solid state light source for maximum brightness, which necessarily results in a dimming of the solid state light source.

13. A lighting system comprising a power adaptor as defined in claim 1 and a lighting unit including at least one solid state light source.

14. A lighting system as claimed in claim 13, wherein the lighting system includes a power reducing device.