Light degradation sensing led signal with visible fault mode

• US 6,667,623 B2
• Filed: 11/07/2001
• Issued: 12/23/2003
• Est. Priority Date: 11/07/2001
• Status: Expired due to Term

• Current Assignee: Current Lighting Solutions, LLC (f/k/a GE Lighting Solutions, LLC) (American Industrial Partners)
• Original Assignee: Gelcore (General Electric Company)
• Inventors: Bourgault, Jean-Simon, Boisvert, Claude
• Primary Examiner(s): Le, N.
• Assistant Examiner(s): Dole, Timothy J.
• Application Number:
  US10/039,407
• Publication Number:
  US 20030085710A1
• Time in Patent Office: 776 Days
• Field of Search: 324/414, 362/800, 340/815.45, 340/907, 340/463
• US Class Current: 324/414
• CPC Class Codes: G01R 31/2635 Testing light-emitting diodes, laser diodes or photodiodes
• CPC Class Codes: H05B 45/10 Controlling the intensity of the light
• CPC Class Codes: H05B 45/30 Driver circuits
• CPC Class Codes: H05B 45/48 having LEDs organised in strings and incorporating parallel shunting devices
• CPC Class Codes: H05B 45/58 involving end of life detection of LEDs

Abstract

A light emitting diode (LED) signal with an LED light output monitoring sensor. If the LED light output drops below a pre-set level, an output signal of the sensor via a comparator and deactivation circuit, deactivates one or more LEDs creating a visible fault display aspect, thereby visually indicating signal failure but allowing a continued use of the signal prior to replacement.

Claims

1. An LED signal with a visual failure mode comprising:

a housing having an interior area,

a plurality of LEDs,

a light sensing means,

a comparator means, and

a disablement means;

the plurality of LEDs arranged and configured within said interior area of said housing;

the light sensing means located within the interior area of the housing, having an output value relative to a light level within the housing;

the comparator means comparing the output value to a reference value;

the comparator initiates the disablement means which deactivates at least one of the LEDs if the output value is below the reference value.

2. The LED signal of claim 1, wherein:

the light sensing means is a phototransistor.

3. The LED signal of claim 1, wherein:

the comparator means is a voltage comparator circuit.

4. The LED signal of claim 1, wherein:

the disablement means is a transistor switch that creates a short circuit across the LED(s) to be deactivated.

5. The LED signal of claim 1, further including:

a time delay circuit

the time delaying circuit delaying the initiation by the comparator means of the disablement means.

6. An apparatus for detecting LED light degradation and initiating a visible failure mode comprising:

a light sensing means for detecting an output level of at least one LED(s),

a comparator means, and

a disablement means;

the light sensing means having an output value relative to a light level emitted by the LED(s);

the comparator means comparing the output value to a reference value, representing a degradation light output level;

if the output value is below the reference value the comparator initiates the disablement means, deactivating at least one of the LED(s).

7. The Apparatus of claim 6, wherein:

the light sensing means is a phototransistor.

8. The Apparatus of claim 6, wherein:

the comparator means is a voltage comparator circuit.

9. The Apparatus of claim 6, wherein:

the disablement means is a transistor switch that creates a short circuit across the LED(s) to be deactivated.

10. The apparatus of claim 6, further including:

a time delay circuit

the time delaying circuit delaying the initiation by the comparator means of the disablement means.

11. A method for creating a visual failure mode in an LED light source with a plurality of LEDs, comprising the steps of:

sensing a light output of the LED light source;

comparing the light output to a reference; and

de-activating at least one of the LEDs if the light output is less than the reference.

12. The method of claim 11 wherein the at least one LED(s) are de-activated by the step of activating a switch that creates a short circuit across the at least one LED(s).

13. The method of claim 11 further including the step of requiring the light output to be less than the reference for a delay period prior to the step of de-activating at least one of the LED(s).

14. An apparatus for detecting a LED light degradation output and initiating a visual failure mode in an LED signal with a plurality of LEDs comprising:

a light sensor,

a comparator, and

a switch;

the light sensor sensing an LED light output level and outputting an electrical signal proportional to the LED light output level,

the comparator comparing the electrical signal to a reference electrical signal and operating the switch if the electrical signal is below the reference electrical signal,

the switch de-activating at least one of the plurality of LEDs.

15. The apparatus of claim 14 further including:

a time delay circuit,

the time delay circuit delay operation of the switch by the comparator.