ILLUMINATING DEVICE WITH LIGHT BUFFER

• US 20100201284A1
• Filed: 09/24/2008
• Published: 08/12/2010
• Est. Priority Date: 09/24/2007
• Status: Active Grant

• Current Assignee: OSRAM GmbH (Ams-Osram AG)
• Original Assignee: OSRAM GmbH (Ams-Osram AG)
• Inventors: Kraus, Robert
• Granted Patent: US 8,497,621 B2
• Time in Patent Office: Days
• US Class Current: 315/294
• CPC Class Codes: F21K 9/232 specially adapted for generating an essentially omnidirectional light distribution, e.g. with a glass bulb
• CPC Class Codes: F21K 9/27 Retrofit light sources for lighting devices with two fittings for each light source, e.g. for substitution of fluorescent tubes
• 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 3/04 characterised by materials, surface treatments or coatings
• CPC Class Codes: F21V 3/08 the material comprising photoluminescent substances
• CPC Class Codes: F21V 3/12 the coatings comprising photoluminescent substances
• 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]

Abstract

A light-emitting device may include at least one light source, which is configured for at least one of AC and PWM operation; and at least two optical buffers for absorbing light energy from the light source and for temporally delayed emission of the stored luminous energy, wherein the at least two optical buffers have different relaxation times and are sensitive to different wavelengths.

Claims

1. A light-emitting device, comprising:

at least one light source, which is configured for at least one of AC and PWM operation; and

at least two optical buffers for absorbing light energy from the light source and for temporally delayed emission of the stored luminous energy, wherein the at least two optical buffers have different relaxation times and are sensitive to different wavelengths.

2. The light-emitting device as claimed in claim 1, the at least two optical buffers comprising a layered near-zone optical buffer in the direct vicinity of the at least one light source and a far-zone optical buffer, which is applied in layered fashion to a bulb.

3. The light-emitting device as claimed in claim 2, further comprising:

a diffusely scattering intermediate-zone optical buffer, which surrounds the near-zone optical buffer and is surrounded by the far-zone optical buffer.

4. The light-emitting device as claimed in claim 1,

wherein the optical buffer which is sensitive to the shortest wavelength has the longest_relaxation time.

5. The light-emitting device as claimed in claim 1,

wherein that optical buffer of the at least one light source which is sensitive to the shortest wavelength is arranged next.

6. The light-emitting device as claimed in claim 1,

wherein the optical buffer comprises phosphor.

7. The light-emitting device as claimed in claim 1,

wherein at least one of the optical buffers has, in addition, a wavelength-converting property.

8. The light-emitting device as claimed in claim 1,

wherein the optical buffer which is sensitive to the shortest wavelength has the longest_relaxation time;

wherein at least one of the optical buffers has, in addition, a wavelength-converting property;

wherein the optical buffer which is sensitive to the shortest wavelength does not have a significant amount of wavelength conversion material.

9. The light-emitting device as claimed in claim 7,

wherein the wavelength conversion material comprises phosphor.

10. The light-emitting device as claimed in claim 1,

wherein a half-value decay time of the optical buffer is at least 1 ms.

11. The light-emitting device as claimed in claim 1,

wherein the light source is configured to be operated on alternating current.

12. The light-emitting device as claimed in claim 11, wherein a relaxation time of at least one optical buffer is greater than the period of the AC voltage.

13. The light-emitting device as claimed in claim 12, wherein the relaxation time of the at least one optical buffer is greater than five times the period of the AC voltage.

14. The light-emitting device as claimed in claim 13, wherein the relaxation time is ten times longer than the period of the AC voltage, but shorter than fifty times the period of the AC voltage.

15. The light-emitting device as claimed in claim 1,

wherein the light source is a UV light-emitting diode.

16. The light-emitting device as claimed in claim 1,

which has, as light source, a chain comprising a plurality of LEDs, which are connected back-to-back in parallel and can be connected directly to the power source.

17. The light-emitting device as claimed in claim 1,

which has a driver for driving the at least one light source, said driver comprising a rectifier without a smoothing capacitor or with a smoothing capacitor which only has small dimensions.

18. The light-emitting device as claimed in claim 1,

which has an incandescent lamp base.

19. The light-emitting device as claimed in claim 1,

which is configured to be inserted into a fluorescent lamp lampholder.

20. A method for illumination, comprising:

operating a light source at least one of on alternating current and in the PWM operating mode;

absorbing luminous energy emitted by the light source by at least one optical buffer;

emitting the absorbed luminous energy again with a time delay;

wherein the at least two optical buffers have different_relaxation times and are sensitive to different wavelengths.