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US 7,723,740 B2Granted
Light emitting device
AssigneeNichia Corporation
InventorsSuguru Takashima, Masatoshi Kameshima, Hiroto Tamaki, Junji Takeichi, Yoshinori Murazaki, Shinpei Kinoshita
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Abstract
A light emitting device that light of various colors by blending lights emitted by two or more kinds of fluorescent materials which are substantially directly excited by light emitted by an excitation source having principal emission peak in a range from 250 nm to 500 nm. Each of the fluorescent materials is of a direct-transition type.
Claims13
A light emitting device comprising:
- at least two kinds of fluorescent material which are to be substantially directly excited, by light emitted from an excitation source having a principal emission peak in a wavelength region of from 250 nm to 420 nm, so as to emit light that is blended to produce light of various colors,
- wherein said at least two kinds of fluorescent material include at least one of
- (i) an oxynitride-based fluorescent material having crystallinity, and represented by a chemical formula of LM2O2N2:R or LM2QTO2N2+T:R (0<T<0.5), where L is at least one kind of Group II element selected from the group consisting of Mg, Ca, Sr, Ba and Zn;
- M is at least one kind of Group IV element selected from the group consisting of C and Si;
- Q is Boron;
- O is oxygen;
- N is nitrogen;
- and R is a rare earth element;
- and
- (ii) a nitride-based fluorescent material, and
- wherein light emitting efficiency of said at least two kinds of fluorescent material when excited by light emitted from the excitation source is at least 60% of a maximum light emission efficiency over the wavelength region of from 250 to 420 nm.
8 more elements
A light emitting device comprising:
- at least two kinds of a first fluorescent material which are to be substantially directly excited by light emitted from an excitation source having a principal emission peak in a wavelength region of from 250 nm to 420 nm;
- and
- a second fluorescent material that is to be excited by part of light emitted from said at least two kinds of the first fluorescent material,
- wherein light emitted from said at least two kinds of the first fluorescent material and light emitted from said second fluorescent material are to be blended so as to produce light of various colors, and
- wherein said at least two kinds of the first fluorescent material include at least one of
- (i) an oxynitride-based fluorescent material having crystallinity, and represented by a chemical formula of LM2O2N2:R or LM2QTO2N2+T:R (0<T<0.5), where L is at least one kind of Group II element selected from the group consisting of Mg, Ca, Sr, Ba and Zn;
- M is at least one kind of Group IV element selected from the group consisting of C and Si;
- Q is Boron;
- O is oxygen;
- N is nitrogen;
- and R is a rare earth element;
- and
- (ii) a nitride-based fluorescent material, and
- wherein light emission efficiency of said at least two kinds of the first fluorescent material when excited by light emitted from the excitation source is at least 60% of a maximum light emission efficiency over the wavelength region of from 250-420 nm.
11 more elements
Dependencies are inferred from the claim text.