Light transmission control for masking appearance of solid state light sources

• US 10,546,846 B2
• Filed: 07/23/2010
• Issued: 01/28/2020
• Est. Priority Date: 07/23/2010
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Lowes, Theodore Douglas
• Primary Examiner(s): Sengdara, Vongsavanh
• Application Number:
  US12/842,639
• Publication Number:
  US 20120018754A1
• Time in Patent Office: 3,476 Days
• Field of Search: 257 98, 257100, 257 99, 257E33058, 257E33059, 257E33061, 257E33067
• 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 9/64 using wavelength conversion means distinct or spaced from the light-generating element, e.g. a remote phosphor layer
• CPC Class Codes: F21V 14/00 Controlling the distribution of the light emitted by adjustment of elements reflectors with provision for adjusting the curvature F21V7/16; light filters or the like with provision for controlling the colour or intensity F21V9/40; screens using adjustable parallel laminae or strips F21V11/04; screens using iris-type diaphragms F21V11/10; screens using movable sheets without apertures F21V11/18; adjustable mountings for lighting devices F21V21/14
• CPC Class Codes: F21V 14/003 by interposition of elements with electrically controlled variable light transmissivity, e.g. liquid crystal elements or electrochromic devices
• CPC Class Codes: F21V 29/505 of reflectors
• CPC Class Codes: F21V 29/74 with fins or blades
• CPC Class Codes: F21V 29/89 Metals
• CPC Class Codes: F21V 3/02 characterised by the shape
• CPC Class Codes: F21V 3/12 the coatings comprising photoluminescent substances
• CPC Class Codes: F21Y 2113/13 comprising an assembly of point-like light sources
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: G02F 1/0147 based on thermo-optic effects G02F1/132 takes precedence
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 1/13718 based on a change of the texture state of a cholesteric liquid crystal
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 25/167 comprising optoelectronic devices, e.g. LED, photodiodes
• CPC Class Codes: H01L 2924/00 : Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00012 : Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 : the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/181 : Encapsulation
• CPC Class Codes: H01L 33/44 : characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: H01L 33/50 : Wavelength conversion elements

Abstract

A light emitter device, package, or lamp that comprises and light emitter and a light transmission control material to mask the appearance of at least the light emitter. In one embodiment, a light emitting diode (LED) based lamp is disclosed, comprising an LED light source. A phosphor is arranged remote to the light source such that light emitted from the light source passes through this phosphor and is converted by this phosphor. A light transmission control material is applied at least partially outside the LED light source and the phosphor to reversibly mask the appearance of the LED light source and the phosphor. The light transmission control material is less masking when the LED light source is active. A method for masking the appearance of inactive light emitters is also disclosed that comprising providing at least one light emitter. Each of the at least one light emitters is provided with a light transmission control material over the light emitters to reversibly mask the appearance of the light emitters while the light emitters are inactive. The light transmission control material is less masking when the LED light source is active.

Claims

1. A light emitting diode (LED) chip, comprising:

an LED; and

a phosphor layer over at least a portion of said LED;

a light transmission control coating at least partially covering said LED, said light transmission control coating comprising a material configured to mask the appearance of said at least partially covered LED when said LED is inactive, wherein said material is configured to change to a non-masking state in response to an electrical signal applied to said light transmission control coating, said light transmission control coating planarized to expose at least one electrical connection of said LED, wherein said light transmission control coating is distinct from and at least partially covers said phosphor layer.

2. The LED chip of claim 1, wherein said light transmission control coating becomes less masking in response to an increase in temperature.

3. The LED chip of claim 2, wherein said light transmission control coating is thermally coupled to said LED chip.

4. The LED chip of claim 1, wherein said light transmission control coating is electrically coupled to said LED.

5. The LED chip of claim 1, wherein said light transmission control coating comprises a polymer.

6. The LED chip of claim 1, wherein said light transmission control coating causes less than 4% emission loss when said LED is active.

7. The LED chip of claim 1, wherein said light transmission control coating becomes less masking in response to an optical stimulus.

8. A light emitting diode (LED) package comprising:

an LED chip;

an optical cavity for holding said LED chip;

package leads electrically connected to said LED chip;

encapsulation comprising a lens portion surrounding said LED chip and electrical connections; and

a light transmission control material over said LED chip and said lens portion, wherein said light transmission control material comprises a material configured to mask the appearance of said LED chip when said LED chip is inactive, and said material is configured to change from a masking state to a light transmitting state in response to an electrical signal applied to said material, wherein said ,optical cavity separates said light transmission control material from said LED chip and said encapsulation.

9. The LED package of claim 8, wherein said light transmission control material is included within a coating at least partially on said encapsulation.

10. The LED package of claim 8, wherein said light transmission control material is within said encapsulation.

11. The LED package of claim 8, wherein said light transmission control material is less masking when said LED chip is active.

12. The LED package of claim 11, wherein said light transmission control material causes at most 4% emission loss when said LED chip is active.

13. The LED package of claim 8, wherein said light transmission control material changes from masking to transmitting in response to increases in temperature.

14. The LED package of claim 13, wherein said light transmission control material is thermally coupled to said LED chip.

15. The LED package of claim 14, wherein said thermal coupling includes a conductive material in thermal contact with the light transmission control material.

16. The LED package of claim 15, wherein said conductive material is transparent.

17. The LED package of claim 8, wherein said light transmission control material is electrically coupled to said LED chip.

18. The LED package of claim 17, wherein said light transmission control material is electrically coupled to said LED chip using a transparent electrode.

19. The LED package of claim 8, wherein said light transmission control material changes from masking to light transmitting in response to light.

20. The LED package of claim 8, wherein said light transmission control material is applied to said encapsulation by molding.

21. A light emitting diode (LED) based lamp, comprising:

an LED light source;

encapsulation comprising a lens portion over and surrounding said LED light source;

a phosphor remote to said LED light source such that light emitted from said LED light source passes through said phosphor and is converted by said phosphor, wherein an optical cavity separates said phosphor from said LED light source and said encapsulation; and

a light transmission control material over said encapsulation, said LED light source and said phosphor, said light transmission control material comprising a material configured to mask the appearance of said LED light source and said phosphor when said LED is inactive and to transmit at least some light emitted from said LED and/or said phosphor in response to an electrical signal applied to said light transmission control material.

22. The LED based lamp of claim 21, wherein said light transmission control material comprises a coating at least partially on said phosphor.

23. The LED based lamp of claim 21, further comprising a cover over said LED light source and said phosphor.

24. The LED based lamp of claim 23, wherein said cover is coated with said light transmission control material.

25. The LED based lamp of claim 23, wherein said cover is comprised of said light transmission control material.

26. The LED package of claim 23, wherein said cover disperses light in a pre-determined pattern.

27. The LED based lamp of claim 21, wherein said light transmission control material is less masking when said LED light source is active.

28. The LED based lamp of claim 27, wherein said light transmission control material allows at least 96% of light emission when said LED light source is active.

29. The LED based lamp of claim 21, wherein said light transmission control material changes from masking to light transmitting in response to changes in temperature.

30. The LED based lamp of claim 29, wherein said light transmission control material is thermally coupled to said LED light source.

31. The LED based lamp of claim 21, wherein said light transmission control material is electrically coupled to said LED light source.

32. The LED package of claim 21, wherein said light transmission control material is applied to said encapsulation by compression molding.

33. The LED based lamp of claim 21, wherein said light transmission control material changes from masking to light transmitting in response to optical stimulus.

34. A light emitting device, comprising:

a light emitting diode (LED); and

a diffusing material at least partially covering said LED and comprising a light scattering ability which varies with temperature, wherein an optical cavity separates said diffusing material from said LED, wherein said diffusing material is configured such that its light scattering ability decreases as the temperature of said diffusing material increases and its light scattering ability increases as the temperature of said diffusing material decreases.

35. The device of claim 34, wherein said diffusing material'"'"'s light scattering ability further varies with exposure to an electric field, wherein said diffusing material is configured such that its light scattering ability decreases as said diffusing material is exposed to an increasing electric field and its light scattering ability increases as said diffusing material is exposed to a decreasing electric field.

36. A light emitting device, comprising:

a light emitting diode (LED);

a heat sink structure comprising an optical cavity for holding said LED;

a light transmission control material optically coupled to said LED, said light transmission control material configured to be light scattering and thereby mask the appearance of said LED when said LED is inactive and to change from light scattering to less light scattering in response to light from said LED, wherein said optical cavity separates said light transmission control material from said LED;

a shaped cover coated with said light transmission control material mounted over said optical cavity; and

a phosphor layer separate from said light transmission control material;

said device forming a bulb.