Light source having phosphor including divalent, trivalent and tetravalent elements

• US 8,441,180 B2
• Filed: 01/03/2011
• Issued: 05/14/2013
• Est. Priority Date: 07/09/2004
• Status: Active Grant

• Current Assignee: Citizen Electronics Company Limited, Nichia Corporation
• Original Assignee: Dowa Electronics Materials Co. Ltd. (DOWA Holdings Company Limited), Nichia Corporation
• Inventors: Nagatomi, Akira, Gotoh, Masahiro, Sakane, Kenji, Yamashita, Shuji
• Primary Examiner(s): Williams, Joseph L
• Application Number:
  US12/929,134
• Publication Number:
  US 20110115366A1
• Time in Patent Office: 862 Days
• Field of Search: 313/503, 313/498, 313/512, 252/301.F, 257/98
• US Class Current: 313/503
• CPC Class Codes: C09K 11/0883 Arsenides; Nitrides; Phosphides
• CPC Class Codes: C09K 11/77347 Silicon Nitrides or Silicon Oxynitrides
• CPC Class Codes: C09K 11/77348 Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

A phosphor having an excitation band relative to lights in the wide range of wavelengths from ultraviolet to visible light, and having an emission spectrum in the red range and so on, with a wide half value width, and an LED and a light source using the phosphor and emitting white and other color lights with good color rendering properties are provided. Powdered raw materials of Ca₃N₂ (2N), CaO (2N), AlN (3N), Si₃N₄ (3N), and Eu₂O₃ (3N) are prepared, and the respective raw materials are mixed to have a mole ratio of the respective elements of Ca:Al:Si:Eu=0.985:1:1:0.015. The mixed raw materials are fired at 1000° C. or higher in an inert atmosphere for three hours, and thereafter pulverized to obtain a phosphor having a composition of CaAlSiN_2.83O_0.25:Eu, which is one example of the phosphor satisfying the above described object. Furthermore, by combining the phosphor with an appropriate LED or a light source emitting from ultraviolet light to visible light, the LED and the light source emitting white and other color lights with good color rendering properties can be obtained.

Claims

1. A phosphor represented by a composition formula M_mB_bO_oN_n:

Z_z, wherein

the element M is one or more kinds of elements selected from a group consisting of Mg, Ca, Sr, Ba, and Zn,

the element B is Si,

the element O is oxygen,

the element N is nitrogen, and

the element Z is one or more kinds of elements selected from a group consisting of Eu, Ce, and Mn; and

formulae m=a+p, b=3, o=a+q, n=4+r, 0<

a≦

10, −

a/2<

p<

a/2, −

a/2<

q<

a/2, and −

2<

r<

2 are satisfied in the composition formula M_mB_bO_oN_n;

Z_z.

2. The phosphor according to claim 1, Wherein

the element M is Ca or Sr,

and

the element Z is Eu.

3. The phosphor according to claim 1, wherein,

when a monochromatic excitation light in a range from 250 nm to 550 nm is irradiated to the phosphor, in a case that luminescence intensity at an excitation wavelength where intensity of a spectrum of a light emitted by absorbing the excitation light becomes maximum is defined as P_H, and luminescence intensity at an excitation wavelength where intensity of the spectrum of the emitted light becomes minimum is defined as P_L,

a formula P_H/P_L≦

2 is satisfied.

4. The phosphor according to claim 3, wherein

an emission maximum of the spectrum of the emitted light is in a range of 580 nm or more and 680 nm or less, and

a half value width of the spectrum of the emitted light is 50 nm or more.

5. A light emitting diode, comprising:

the phosphor according to claim 1; and

a light emitting portion emitting light comprising a wavelength of 250 nm to 550 nm,

wherein the phosphor emits light by using the light comprising a wavelength of 250 nm to 550 nm as an excitation source.