Emergency lighting devices with LED strings

Patent metadata

Field	Value
Publication number	US-9871404-B2
Application number	US-201213676791-A
Country	US
Kind code	B2
Filing date	Nov 14, 2012
Priority date	Dec 12, 2011
Publication date	Jan 16, 2018
Grant date	Jan 16, 2018

Abstract

Emergency lighting devices and methods are disclosed. An emergency lighting device includes a first group of solid state emitters configured to emit light of a first color. The emergency lighting device also includes a second group connected in series to the first group and configured to emit a second color. The groups are configured to receive a normal operation current from an LED driver at the input end of the first group and output the normal operation current at the output end of the second group. In an emergency, the first group receives an emergency operation current from an emergency LED driver at an emergency input and outputs the emergency operation current at an emergency output located.

First claim

What is claimed is:

1. An emergency lighting device comprising:
a first group of solid state emitters connected in a first string and configured to emit light of a first color, the first group of solid state emitters having an input end and an output end;
a second group of solid state emitters connected in a second string and configured to emit light of a second color, the second group of solid state emitters having an input end and an output end, wherein the input end of the second group of solid state emitters is electrically connected in series to the output end of the first group of solid state emitters;
wherein the first group of solid state emitters is configured to receive a normal operation current at the input end of the first group of solid state emitters, and the second group of solid state emitters is configured to output the normal operation current at the output end of the second group of solid state emitters; and
wherein the first group of solid state emitters is configured to receive an emergency operation current at an emergency input that is different from the input end of the first group of solid state emitters and output the emergency operation current at an emergency output, wherein the emergency input and the emergency output are located between the input end of the first group of solid state emitters and the output end of the second group of solid state emitters such that the emergency operation current is supplied to a first plurality of the first group of solid state emitters and not to a second plurality of the first group of solid state emitters,
wherein the first color is different than the second color.

2. The emergency lighting device of claim 1 , wherein the emergency input and the emergency output are located between the input end and the output end of the first group of solid state emitters such that the first group of solid state emitters emits light of the first color and the second group of solid state emitters emits no light such that the emergency lighting device emits light of the first color rather than a mixture of the first color and the second color.

3. The emergency lighting device of claim 1 , wherein the emergency input is located between the input end of the first group of solid state emitters and the output end of the first group of solid state emitters, and wherein the emergency output is located between the input end of the second group of solid state emitters and the output end of the second group of solid state emitters such that the emergency operation current is supplied to a first plurality of the second group of solid state emitters and not to a second plurality of the second group of solid state emitters in response to the normal operation current.

4. The emergency lighting device of claim 3 , wherein the first group of solid state emitters is configured to emit a first non-white light and the second group of solid state emitters is configured to emit a second non-white light.

5. The emergency lighting device of claim 4 , wherein a ratio of a number of solid state emitters of the first group of solid state emitters between the emergency input and the output of the first group of solid state emitters to a number of solid state emitters of the second group of solid state emitters between the input end of the second group of solid state emitters and the emergency output is configured to emit a mixture of light of a target color that is different from a nominal color of combined light emitted by the first group of solid state emitters and the second group of solid state emitters.

6. The emergency lighting device of claim 5 , wherein the first group of solid state emitters is configured to emit blue shifted yellow (BSY) light, the second group of solid state emitters is configured to emit red light and the ratio is configured such that the target color is a white light with a Color Rendering Index (CRI) of at least 80.

7. The emergency lighting device of claim 4 , wherein a ratio of a number of solid state emitters of the first group of solid state emitters between the emergency input and the output of the first group of solid state emitters to a number of solid state emitters of the second group of solid state emitters between the input end of the second group of solid state emitters and the emergency output is configured to emit a mixture of light of a target color that is different from the first color of the first group of solid state emitters and the second color of the second group of solid state emitters.

8. The emergency lighting device of claim 3 , wherein a number of solid state emitters of the first group of solid state emitters between the emergency input and the output of the first group of solid state emitters and a number of solid state emitters of the second group of solid state emitters between the input end of the second group of solid state emitters and the emergency output are configured based on an available emergency current.

9. The emergency lighting device of claim 1 , wherein the locations of the emergency input and emergency output are mechanically adjustable.

10. A method of operating an emergency lighting device, comprising:
receiving a normal operation current at a first group of solid state emitters and a second group of solid state emitters such that the normal operation current is input at an input end of the first group of solid state emitters and output at an output end of the second group of solid state emitters;
detecting a loss of input power to the emergency lighting device; and
upon the loss of the input power, supplying an emergency operation current at an emergency input that is different from the input end of the first group of solid state emitters and outputting the emergency operation current at an emergency output,
wherein the emergency input and the emergency output are located at respective locations between the input end of the first group of solid state emitters and the output end of the second group of solid state emitters,
wherein the respective locations are different from the input end of the first group of solid state emitters and the output end of the second group of solid state emitters, and
wherein the first group of solid state emitters is configured to emit light of a first color, and the second group of solid state emitters is configured to emit light of a second color, different from the first color.

11. The method of claim 10 , wherein the emergency input and the emergency output are located between the input end and an output end of the first group of solid state emitters.

12. The method of claim 10 , wherein the receiving an emergency operation current comprises receiving a current that is less than the normal operation current.

13. The method of claim 10 , wherein the emergency input is located between the input end of the first group of solid state emitters and the output end of the first group of solid state emitters, and wherein the emergency output is located between the input end of the second group of solid state emitters and the output end of the second group of solid state emitters.

14. The method of claim 13 , wherein the receiving an emergency operation current causes the first group of solid state emitters and the second group of solid state emitters to maintain a color emitted with the normal operation current.

15. The method of claim 13 , further comprising adjusting a ratio of a number of solid state emitters of the first group of solid state emitters between the emergency input and the output of the first group of solid state emitters to a number of solid state emitters of the second group of s

Assignees

• Cree Inc

Inventors

• Mcbryde James Andrew
• Taylor Jason

Classifications

• H02J7/56

  Active balancing, e.g. using capacitor-based, inductor-based or DC-DC converters · CPC title

• F21Y2115/10

  Light-emitting diodes [LED] · CPC title

• H05B41/46

  Circuits providing for substitution in case of failure of the lamp · CPC title

• H05B45/46

  having LEDs disposed in parallel lines · CPC title

• F21S9/022

  Emergency lighting devices · CPC title