Illumination control system

• US 20030057888A1
• Filed: 08/28/2002
• Published: 03/27/2003
• Est. Priority Date: 08/30/2001
• Status: Active Grant

• Current Assignee: Radiant Research Drive, Radiant Research Limited
• Original Assignee: Radiant Research Limited
• Inventors: Anderson, Keith, Archenhold, Geoffrey Howard Gillett
• Granted Patent: US 6,963,175 B2
• Time in Patent Office: Days
• US Class Current: 315/291
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/24 using electrical feedback from LEDs or from LED modules
• CPC Class Codes: H05B 45/28 using temperature feedback
• CPC Class Codes: H05B 45/32 Pulse-control circuits
• CPC Class Codes: H05B 45/33 Pulse-amplitude modulation [PAM]
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

A light emitting diode illumination control system is disclosed for driving a current circuit for energising one or more LED light sources. The system comprises a control system including a microprocessor arranged to control a pulse amplitude modulated (PAM) voltage controlled current circuit, and may employ a monitor for monitoring at least one ambient condition and a microprocessor operable to control the current circuit in response to the monitored condition.

Claims

1. A light emitting diode illumination system arranged to drive one or more light emitting diode light sources which comprises a control system including a microprocessor arranged to control a pulse amplitude modulated (PAM) voltage controlled current circuit.

2. An illumination system according to claim 1, wherein said system is arranged to control a plurality of light sources which are adapted, inter se, to emit light within different wavelength bands.

3. An illumination system according to claim 2, wherein said light sources are, inter se, adapted to emit substantially monochromatic light centred on at least three different wavelengths.

4. An illumination system according to any preceding claim, wherein means is provided for modifying and controlling the pulse amplitude modulation signal timing period and duty cycle.

5. An illumination system according to claim 4, wherein the means provided for modifying and controlling the pulse amplitude modulation signal timing period and duty cycle comprises a micro-processor, discrete electrical component circuit, fixed or programmable crystal oscillator or integrated circuit timer.

6. An illumination system according to any preceding claim, and including means for providing a voltage for modulating pulse amplitude.

7. An illumination system according to claim 6, wherein a programmable digital potentiometer is provided as voltage divider.

8. An illumination system according to any preceding claim, wherein a current feedback monitor is provided for monitoring current driving the light source(s).

9. An illumination system according to claim 8, wherein the current feedback monitor comprises a discrete electrical circuit or current sensing integrated circuit.

10. An illumination system according to any preceding claim, wherein said system comprises a monitor for monitoring at least one ambient condition and a microprocessor adapted to control the current circuit in response to the monitored condition.

11. An illumination system according to any preceding claim, and including a communications module providing a data connection interface to an internal or external controlling device.

12. An illumination system according to any preceding claim, wherein the system comprises means for receiving an external signal and for controlling the frequency and duty cycle of the pulse amplitude modulation control signal in synchronism with that external signal.

13. An illumination system according to claim 12, wherein a solid state camera system is arranged to pass such an external signal.

14. An illumination system according to any preceding claim, the control system being constituted as a closed-loop, solid state, illumination control system.

15. An illumination system substantially as herein described with reference to the accompanying diagrammatic drawings.