EXTENDED PERSISTENCE AND REDUCED FLICKER LIGHT SOURCES

• US 20120268918A1
• Filed: 04/20/2012
• Published: 10/25/2012
• Est. Priority Date: 04/22/2011
• Status: Active Grant

• Current Assignee: Signify North America Corporation (Signify N.V.)
• Original Assignee: Once Innovations Inc. (Signify N.V.)
• Inventors: GRAJCAR, Zdenko
• Granted Patent: US 9,696,011 B2
• Time in Patent Office: Days
• US Class Current: 362/84
• CPC Class Codes: F21K 9/23 Retrofit light sources for lighting devices with a single fitting for each light source, e.g. for substitution of incandescent lamps with bayonet or threaded fittings
• CPC Class Codes: F21K 9/64 using wavelength conversion means distinct or spaced from the light-generating element, e.g. a remote phosphor layer
• CPC Class Codes: F21V 3/12 the coatings comprising photoluminescent substances
• CPC Class Codes: F21V 9/08 for producing coloured light, e.g. monochromatic; for reducing intensity of light with provision for controlling the colour F21V9/40
• CPC Class Codes: F21V 9/38 Combination of two or more photoluminescent elements of different materials
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]
• CPC Class Codes: H05B 45/44 with an active control inside an LED matrix

Abstract

A light source is provided with extended persistence and reduced flicker characteristics by using a light capacitive filter. In general, a light source can include an illumination source which converts electrical energy into emitted light. The illumination source, however, is generally powered by an AC waveform, and the periodic variations inherent in the AC waveform may cause flicker in the emitted light. To reduce the flicker, a light capacitive filter is included in the light source to filter the light emitted by the illumination source and produce a light output with reduced flicker. In some examples, the light capacitive filter includes a medium persistence phosphor having a decay constant (or half-life) of between 1 milliseconds and 2 seconds.

Claims

1. An illumination module for providing reduced flicker illumination, the illumination module comprising:

an illumination source for converting electrical energy into emitted light, wherein the emitted light has a first percent flicker; and

a light capacitive filter for filtering the light emitted by the illumination source to produce the reduced flicker illumination provided by the illumination module,

wherein the reduced flicker illumination has a percent flicker that is lower than the first percent flicker.

2. The illumination module of claim 1, wherein the light capacitive filter absorbs light emitted by the illumination source, and re-emits the absorbed light during a period of time following the absorption.

3. The illumination module of claim 2, wherein the light capacitive filter is a coating of a light persistent phosphor.

4. The illumination module of claim 3, wherein the light capacitive filter is a coating of the light persistent phosphor having the composition SrAl2O4:

Eu2+, Dy3+.

5. The illumination module of claim 2, wherein the light capacitive filter re-emits the absorbed light with a half-life of between 1 millisecond and 2 seconds.

6. The illumination module of claim 1, wherein the illumination source comprises a plurality of light emitting diodes (LEDs).

7. The illumination module of claim 6, wherein the light capacitive filter is a coating applied to a surface of the plurality of LEDs.

8. The illumination module of claim 6, further comprising:

a transparent or translucent wall through which the light emitted by the illumination source passes to provide the illumination of the illumination module,

wherein the light capacitive filter is a coating applied to a surface of the transparent or translucent wall.

9. The illumination module of claim 8, further comprising:

a second coating for filtering at least one of the light emitted by the illumination source and the illumination produced by the light capacitive filter,

wherein the second coating filters light to have a different color as compared to the light produced by the light capacitive filter, and

wherein the second coating is applied to a surface of one of a surface of the plurality of LEDs and the transparent or translucent wall.

10. The illumination module of claim 9, wherein the light capacitive filter is applied to the same one of the surface of the plurality of LEDs and the transparent or translucent wall as the second coating.

11. The illumination module of claim 9, wherein the light capacitive filter is applied to a different one of the surface of the plurality of LEDs and the transparent or translucent wall as the second coating.

12. The illumination module of claim 9, wherein the second coating is formed at least one of a medium persistence phosphor, a low persistence phosphor, a fluorescent dye, and a photo-luminescent dye.

13. The illumination module of claim 1, further comprising:

a second phosphor coating, wherein the second phosphor coating produces light having a different color as compared to the light produced by the light capacitive coating.

14. A light having extended persistence, the light comprising:

an illumination source for producing light by converting electrical energy into produced light; and

a light persistent filter for absorbing light produced by the illumination source and re-emitting the absorbed light during a period of time when the illumination source does not produce light,

wherein the light persistent filter re-emits the absorbed light with a half-life of between 1 millisecond and 2 seconds.

15. The light according to claim 14,

wherein the illumination source does not produce light during a portion of each cycle of an electrical waveform providing the electrical energy, and

wherein the light persistent filter re-emits absorbed light during the portion of each cycle of the electrical waveform.

16. The light according to claim 14 further comprising:

electrical contacts for receiving an electrical signal providing the electrical energy to the light; and

a driver circuit module for processing the electrical signal received at the electrical contacts, and providing the processed electrical signal to the illumination source.

17. The light according to claim 14, wherein the illumination module comprises a light emitting diode (LED).

18. The light according to claim 17, wherein the light persistent filter is a coating applied to a surface of the LED.

19. The light according to claim 17, further comprising:

a light chamber,

wherein the illumination source is located within the light chamber,

wherein the light persistent filter is a coating applied to a surface of the light chamber,

and wherein the light is configured to provide illumination outside of the light chamber.