White light-emitting device
AssigneeKabushiki Kaisha Toshiba
InventorsNaotoshi MATSUDA, Yasushi Hattori, Yumi Fukuda, Iwao Mitsuishi, Keiko Albessard
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Abstract
The embodiment of the present disclosure provides a light-emitting device capable of both realizing neutral white color and having high luminous efficiency. The device has a blue-light emitting semi-conductor element and a luminescent layer containing a mixture of fluorescent substances. The mixture contains first and second phosphors. The first phosphor is activated with Ce and emits luminescence with a peak wavelength of 540 to 560 nm, and the second phosphor emits luminescence with a peak wavelength of 580 to 610 nm and is represented by the following formula (2): (Sr1-x2Eux2) Sia2Alb2Oc2Nd2Ce2 (2).
Claims12
A light-emitting device, comprising
- a semi-conductor element which emits a blue light;
- and
- a luminescent layer containing a mixture of
- (A) a first phosphor which is activated with Ce and which emits luminescence with a peak in the wavelength range of 540 to 560 nm under excitation by blue light, and
- (B) a second phosphor which emits luminescence with a peak in the wavelength range of 580 to 610 nm under excitation by blue light,
- wherein the second phosphor is represented by the following formula (2):
- (Sr1-x2Eux2) Sia2Alb2Oc2Nd2Ce2 (2)
- in which
- x2, a2, b2, c2, d2 and e2 are numbers satisfying the conditions of
- 0<x2≦1,
- 3.5≦a2≦4.0,
- 1.0≦b2≦2.0,
- 0.25≦c2≦1.0,
- 5.5≦d2≦7.0, and
- 0≦e2≦0.1, respectively.
Dependencies are inferred from the claim text.