Method and apparatus for producing untainted white light using off-white emitting diodes

• US 7,206,507 B2
• Filed: 04/26/2006
• Issued: 04/17/2007
• Est. Priority Date: 12/19/2003
• Status: Expired due to Term

• Current Assignee: Epistar Corporation
• Original Assignee: Avago Technologies ECBU IP Singapore Pte Limited (Broadcom, Inc.)
• Inventors: Lee, Soo Ghee, Ng, Kee Yean, Lee, Meng Ee
• Primary Examiner(s): Luebke, Renee
• Assistant Examiner(s): BANNAN, JULIE A
• Application Number:
  US11/412,297
• Publication Number:
  US 20060198137A1
• Time in Patent Office: 356 Days
• Field of Search: 396/182, 396/176, 396/155, 257/89, 313502-503
• US Class Current: 396/182
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/49175 Parallel arrangements
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• 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 2924/09701 Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: H05B 45/00 Circuit arrangements for operating light-emitting diodes [LED]
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/40 Details of LED load circuits

Abstract

A white light emitting device by using off-white light emitting diodes (LED'"'"'s). Rather than using just pure white LEDs, the white light emitting device arranges those LEDs which exhibit off-white colors in a manner such that the combination of light emanating from these off-white LEDs produces a radiation which appears substantially pure white to the human eye.

Claims

1. A camera comprising a flash apparatus, wherein said flash apparatus comprises:

an array of light emitting diodes (LEDs), said array comprising;

a purplish-white LED comprising;

a first blue LED emitting a first blue light in a wavelength range of 460–

465 nm; and

a first layer of yellow phosphor encapsulant, wherein said first layer is positioned over said first blue LED, and wherein said first layer converts said first blue light to purplish-white light; and

a greenish-white LED comprising;

a second blue LED emitting a second blue light in a wavelength range of 470–

480 nm; and

a second layer of yellow phosphor encapsulant, wherein said second layer is positioned over said second blue LED, and wherein said second layer converts said second blue light to greenish-white light, wherein a combination of said purplish-white light and said greenish-white light is pure white light, wherein said pure white light has a color temperature of approximately 6500 Kelvins.

2. The camera of claim 1, wherein said array comprise a 1×

3 matrix of light emitting diodes comprising said purplish-white light emitting diode, said white light emitting diode, and said greenish-white light emitting diode.

3. The camera of claim 1, wherein said array comprises a 2×

2 matrix comprising;

a first purplish-white light emitting diode in an upper left corner;

a second purplish-white light emitting diode in a bottom right corner;

a first greenish-white light emitting diode in an upper right corner; and

a second greenish-white light emitting diode in a bottom left corner.

5. The camera of claim 1, wherein said camera is a digital camera.

6. The camera of claim 5, wherein said digital camera is a component of a mobile communication device.

7. The camera of claim 6, wherein said mobile communication device is a cellular phone.

8. The camera of claim 1, wherein said array comprises a 2×

2 matrix comprising;

a first greenish-white light emitting diode in an upper left corner;

a second greenish-white light emitting diode in a bottom right corner;

a first purplish-white light emitting diode in an upper right corner; and

a second purplish-white light emitting diode in a bottom left corner.

4. A mobile communication device comprising a flash apparatus for image capturing, wherein said flash apparatus comprises an array of white light emitting diodes, wherein said array comprises a purplish-white light emitting diode and a greenish-white light emitting diode, wherein a composite light has a color that is pure white to the human eye.