Light emitting apparatus

• US 7,569,987 B2
• Filed: 08/30/2005
• Issued: 08/04/2009
• Est. Priority Date: 08/31/2004
• Status: Active Grant

• Current Assignee: Nichia Corporation
• Original Assignee: Nichia Corporation
• Inventors: Naitou, Takahiro
• Primary Examiner(s): Patel; Nimeshkumar D.
• Assistant Examiner(s): Hines; Anne M
• Application Number:
  US11/213,860
• Publication Number:
  US 20060043879A1
• Time in Patent Office: 1,435 Days
• Field of Search: 315/246, 313498-512
• US Class Current: 313/503
• CPC Class Codes: C09K 11/0883 Arsenides; Nitrides; Phosphides
• CPC Class Codes: C09K 11/7728 containing europium
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• 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 33/50 Wavelength conversion elements
• CPC Class Codes: H01L 33/60 Reflective 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

Abstract

An object of the present invention is to provide a light emitting apparatus that allows it to easily control the driving of LED and has high color rendering properties.

The light emitting apparatus comprises the first light emitting device 108a that has first peak emission wavelength in blue region and emits blue light, the fluorescent material 140 that is excited by the light from the first light emitting device 108a and emits red light, the second light emitting device 108b that has second peak emission wavelength which is longer than the first peak emission wavelength and is shorter than peak emission wavelength of the fluorescent material 140, and the second light emitting device 108b that emits green light of second peak emission wavelength which is longer than the first peak emission wavelength, so as to emit light generated by blending of blue light, green light and red light to the outside.

Claims

1. A light emitting apparatus comprising;

a first light emitting device that has a first peak emission wavelength in a short wavelength region of visible light,

a fluorescent material that converts light emitted by the first light emitting device to light of a different wavelength and,

a second light emitting device that has a second peak emission wavelength which is longer than the first peak emission wavelength and is shorter than the peak emission wavelength of the fluorescent material, wherein the difference between the first peak emission wavelength and the second peak emission wavelength is 60 nm or larger, and

wherein the light emitted by the first light emitting device, the light emitted by the fluorescent material and the light emitted by the second light emitting device are mixed and emitted to the outside,

wherein said first light emitting device is mounted in a first recess and said second light emitting device is mounted in a second recess, and

wherein

a first line that perpendicularly passes a bottom surface of said first recess at its center, and

a second line that perpendicularly passes said bottom surface at the intersect of a third line that extends along a linear portion one of the side faces of said first recess and a fourth line that extends along a linear portion of another one of the side faces of said first recess,

are offset from each other such that said mixed light has a uniform color.

2. The light emitting apparatus according to claim 1,

wherein the fluorescent material is a nitride fluorescent material that contains at least one kind of group II element selected from the group consisting of Be, Mg, Ca, Sr, Ba and Zn, at least one kind of group IV element selected from the group consisting of C, Si, Ge, Sn, Ti, Zr and Hf, and element N, and is activated with at least one kind of rare earth element selected from among the group consisting of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er and Lu.

3. The light emitting apparatus according to claim 1,

wherein the fluorescent material is excited mainly by the light emitted by the first light emitting device while being complementarily excited by the light emitted by the second light emitting device, so that the fluorescent material produces such an emission spectrum, when excited by the light from the first light emitting device, as the light intensity consists of 100 parts attributable to the light of the first peak emission wavelength emitted by the first light emitting device and 80 parts attributable to the light of the second peak emission wavelength emitted by the second light emitting device.

4. The light emitting apparatus according to claim 1, wherein the openings of said first and second recesses are formed in elliptical shapes arranged side by side along their major axes.

5. The light emitting apparatus according to claim 4, wherein the major axis of at least one of said elliptical shapes is twice as long as the minor axis of said elliptical shape.

6. A light emitting apparatus comprising;

a first light emitting device that has a first peak emission wavelength in a short wavelength region of visible light,

a fluorescent material that converts light emitted by the first light emitting device to light of a different wavelength and,

a second light emitting device that has a second peak emission wavelength which is longer than the first peak emission wavelength and is shorter than the peak emission wavelength of the fluorescent material, wherein the difference between the first peak emission wavelength and the second peak emission wavelength is 60 nm or larger, and

wherein the light emitted by the first light emitting device, the light emitted by the fluorescent material and the light emitted by the second light emitting device are mixed and emitted to the outside,

wherein said first light emitting device is mounted in a first recess and said second light emitting device is mounted in a second recess, and

wherein

a first line that perpendicularly passes a bottom surface of said first recess at its center, and

a second line that perpendicularly passes said bottom surface at the intersect of a third line that extends along a linear portion of one of the side faces of said first recess and a fourth line that extends along a linear portion of another one of the side faces of said first recess,

are situated with respect to each other such that said mixed light has a uniform color.

7. The light emitting apparatus according to claim 6, wherein the openings of said first and second recesses are formed in elliptical shapes different from circles, said elliptical shapes being arranged side by side along their major axes.