LIGHTING CONTROL SYSTEM HAVING A TRIM CIRCUIT

• US 20100156304A1
• Filed: 03/03/2010
• Published: 06/24/2010
• Est. Priority Date: 10/19/2007
• Status: Active Grant

• Current Assignee: American Sterilizer Company (Steris Corporation)
• Original Assignee: American Sterilizer Company (Steris Corporation)
• Inventors: Petrucci, James A., Hite, David A., Drabinski, Terry A., Rice, Sheari A.
• Granted Patent: US 7,990,078 B2
• Time in Patent Office: Days
• US Class Current: 315/185.R
• CPC Class Codes: H05B 45/00 Circuit arrangements for operating light-emitting diodes [LED]
• CPC Class Codes: H05B 45/28 using temperature feedback
• CPC Class Codes: H05B 45/48 having LEDs organised in strings and incorporating parallel shunting devices
• CPC Class Codes: H05B 45/56 involving measures to prevent abnormal temperature of the LEDs
• CPC Class Codes: H05B 45/58 involving end of life detection of LEDs
• CPC Class Codes: H05B 47/235 with communication between the lamps and a central unit

Abstract

A lighting control system suitable for a surgical lighting device. The lighting control system includes circuitry that compensates for the effects of temperature changes in a lighting device, and that compensates for forward voltage variations among LED lighting modules to provide substantially uniform light output.

Claims

1. A lighting control system for a lighting device, the system comprising:

a primary controller;

a plurality of drive controllers electrically connected with the primary controller;

a plurality of drive outputs electrically connected with a drive controller, each drive controller controlling at least one drive output;

a plurality of LED modules, each LED module electrically connected with a drive output and having a plurality of series-connected LEDs, wherein at least one of said plurality of LED modules include;

a trim circuit to compensate for forward voltage variations among said LEDs of the LED module, said trim circuit balancing voltage drop differences across the series-connected LEDs thereby providing substantially uniform lighting for said plurality of LED modules.

2. A lighting control system according to claim 1, wherein said trim circuit includes:

a voltage regulator;

a transistor;

a comparator; and

a potentiometer.

3. A lighting control system according to claim 1, wherein at least one of said plurality of LED modules includes:

a temperature sensing device for sensing temperature in the vicinity of the LED module.

4. A lighting control system according to claim 1, wherein said primary controller monitors a drive current associated with each drive output in order to determine whether one of said plurality of LED modules has an open circuit failure.

5. A lighting control system according to claim 1, wherein said drive output includes circuitry to determine whether an associated LED module has a short circuit failure.

6. A lighting control system according to claim 1, wherein said primary controller operates in a maintenance mode wherein said plurality of LED modules operate at a low duty cycle.

7. A lighting control system according to claim 1, wherein said primary controller operates in a calibration mode allowing tuning of said plurality of LED modules to a LED drive current within a range from a predetermined target drive current.

8. A lighting control system according to claim 1, wherein said system includes a substrate having a plurality of LED modules located thereon.