Light emitting device and system providing white light with various color temperatures

• US 20100061078A1
• Filed: 09/08/2009
• Published: 03/11/2010
• Est. Priority Date: 09/10/2008
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kim, Yu-Sik
• Granted Patent: US 8,297,783 B2
• Time in Patent Office: Days
• US Class Current: 362/84
• CPC Class Codes: F21V 9/30 Elements containing photoluminescent material distinct from or spaced from the light source shades F21V1/17; globes, bowls or cover glasses F21V3/08, F21V3/12; refractors F21V5/10; reflectors F21V7/26, F21V7/30; elements with provision for controlling the spectral properties or intensity F21V9/40
• CPC Class Codes: F21W 2131/103 of streets or roads
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: G02B 6/0023 provided by one optical element, or plurality thereof, placed between the light guide and the light source, or around the light source
• CPC Class Codes: G02B 6/0073 Light emitting diode [LED]
• CPC Class Codes: H01L 2224/0401 Bonding areas specifically adapted for bump connectors, e.g. under bump metallisation [UBM]
• CPC Class Codes: H01L 2224/13 of an individual bump connector
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2924/00011 Not 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 33/50 Wavelength conversion elements
• CPC Class Codes: H05B 33/14 characterised by the chemical or physical composition or the arrangement of the electroluminescent material , or by the simultaneous addition of the electroluminescent material in or onto the light source
• CPC Class Codes: H05B 45/20 Controlling the colour of the light

Abstract

In a light emitting device and system providing white light with various color temperatures are provided, a light emitting device includes a light emitting element (LED) that is operated by a driving bias and emits first light, and a phosphor layer including a phosphor that partially wavelength-converts first light and emits second light, thereby emitting white light using the first light and the second light, wherein the phosphor has a maximum conversion efficiency at a first level of the driving bias, and the LED has a maximum conversion efficiency at a second level of the driving bias, the first level being different from the first level.

Claims

1. A light emitting device comprising a light emitting element (LED) that is operated by a driving bias and emits first light, and a phosphor layer including a phosphor that partially wavelength-converts first light and emits second light, thereby emitting white light using the first light and the second light, wherein the phosphor has a maximum conversion efficiency at a first level of the driving bias, and the LED has a maximum conversion efficiency at a second level of the driving bias, the first level being different from the first level.

2. The light emitting device of claim 1, wherein the color temperature of the white light is varied by adjusting the level of the driving bias.

3. The light emitting device of claim 1, wherein the second light has a dominant wavelength at the first level of the driving bias in the white light, and the first light has a dominant wavelength at the second level of the driving bias in the white light.

4. The light emitting device of claim 1, wherein the LED is a blue LED that emits blue light, and the phosphor is a red phosphor that partially wavelength-converts the blue light and emits red light.

5. The light emitting device of claim 4, wherein the phosphor layer further includes a yellow phosphor that partially wavelength-converts the blue light and emits yellow light, and a green phosphor that partially wavelength-converts the blue light and emits green light.

6. The light emitting device of claim 4, wherein reddish white light is generated at the first level of the driving bias, and bluish white light is generated at the second level of the driving bias.

7. The light emitting device of claim 1, wherein the LED is a UV LED that emits a UV light, the phosphor is a red phosphor that partially wavelength-converts the UV light and emits red light, and the phosphor layer further includes a green phosphor that partially wavelength-converts the UV light and emits green light, and a blue phosphor that partially wavelength-converts the UV light and emits blue light.

8. The light emitting device of claim 7, wherein the blue phosphor has the maximum conversion efficiency at the second level of the driving bias.

19. A light emitting system comprising the light emitting device of claim 1, and a sensor that senses user'"'"'s body temperature, wherein the level of the driving bias is controlled by the sensor.

20. A light emitting system comprising a light emitting device of claim 1.

9. A light emitting device comprising a light emitting element (LED) that is operated by a driving bias and emits first light, a first phosphor that partially wavelength-converts the first light and emits second light, and second phosphor that partially wavelength-converts the first light and emits third light, thereby emitting white light using the first light, the second light and the third light, wherein the first phosphor has a maximum conversion efficiency at a first level of the driving bias, and the second phosphor has a maximum conversion efficiency at a second level of the driving bias, the first level being different from the first level.

10. The light emitting device of claim 9, wherein the color temperature of the white light is varied by adjusting the level of the driving bias.

11. The light emitting device of claim 9, wherein the second light has a dominant wavelength at the first level of the driving bias in the white light, and the third light has a dominant wavelength at the second level of the driving bias in the white light.

12. The light emitting device of claim 9, wherein the LED is a UV LED that emits a UV light, the first phosphor is a red phosphor that partially wavelength-converts the blue light and emits red light, and the second phosphor is a blue phosphor that partially wavelength-converts the UV light and emits blue light.

13. A light emitting device comprising a blue light emitting element (LED) that is operated by a driving bias and emits blue light, and a red phosphor that partially wavelength-converts the blue light and emits red light, thereby emitting white light using the blue light and the red light, wherein reddish white light or bluish white light is generated by adjusting the level of the driving bias.

14. The light emitting device of claim 13, wherein reddish white light is generated at a first level of the driving bias, and bluish white light is generated at a second level of the driving bias, the first level being different from the first level.

15. The light emitting device of claim 14, wherein the second level is higher than the first level.

16. The light emitting device of claim 14, wherein the red phosphor has a maximum conversion efficiency at the first level of the driving bias, and the blue phosphor has a maximum conversion efficiency at the second level of the driving bias.

17. The light emitting device of claim 13, further comprising a yellow phosphor that partially wavelength-converts the blue light and emits yellow light, or a green phosphor that partially wavelength-converts the blue light and emits green light.

18. The light emitting device of claim 13, wherein the driving bias is DC power.