The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 13, 2004
Filed:
Mar. 14, 2002
Masatoshi Shiiki, Musashimurayama, JP;
Masaaki Komatsu, Kokubunji, JP;
Choichiro Okazaki, Kodaira, JP;
Shin Imamura, Kokubunji, JP;
Teruki Suzuki, Funabashi, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
A white light source includes an ultraviolet-visible excitation light generation unit capable of generating visible light and ultraviolet light, and a fluorescence generation unit having a phosphor layer and being capable of generating visible light upon excitation by the ultraviolet light and uses, in the phosphor layer, a red light emitting phosphor represented by the following compositional formula: (Ca Sr Eu )S:M , wherein a, b and c satisfy the following conditions: 0≦a<1.0, 0≦b<0.1 and 0≦c≦0.1; and M is a dopant element having absorption of excitation energy at about 350 nm to about 500 nm. The dopant element M includes rare earth elements such as Ce, Yb, Gd and Tm. By substituting part of Ca and/or Sr with Zn, the white light source can exhibit further improved performances. The white light source exhibits an increased red light component as compared with light emitted from conventional (Y Gd Ce ) (Al Ga ) O green light phosphors and is suitably used in display apparatus.