Light-emitting device and method for designing light emitting device

Patent metadata

Field	Value
Publication number	US-2016308097-A1
Application number	US-201615191734-A
Country	US
Kind code	A1
Filing date	Jun 24, 2016
Priority date	Dec 27, 2013
Publication date	Oct 20, 2016
Grant date	—

Abstract

It is an object of the present invention to improve light source efficiency of “a light-emitting device capable of realizing a natural, vivid, highly visible and comfortable appearance of colors or an appearance of objects” already arrived at by adopting a spectral power distribution having a shape completely different from the shape of conventionally known spectral power distributions while maintaining favorable color appearance characteristics.

First claim

1 . A light-emitting device at least including, as light-emitting elements:
a blue semiconductor light-emitting element; a green phosphor; and a red phosphor, wherein light emitted from the light-emitting device in a main radiant direction satisfies all of Conditions 1 to 4 below Condition 1: when λ denotes wavelength, φ SSL1 (λ) denotes a spectral power distribution of light emitted from the light-emitting device in the main radiant direction, φ ref1 (λ) denotes a spectral power distribution of reference light which is selected in accordance with a correlated color temperature T SSL1 of the light emitted from the light-emitting device in the main radiant direction, (X SSL1 , Y SSL1 , Z SSL1 ) denote tristimulus values of the light emitted from the light-emitting device in the main radiant direction, and (X ref1 , Y ref1 , Z ref1 ) denote tristimulus values of the reference light which is selected in accordance with T SSL1 of the light emitted from the light-emitting device in the main radiant direction, and a normalized spectral power distribution S SSL1 (λ) of the light emitted from the light-emitting device in the main radiant direction, a normalized spectral power distribution S ref1 (λ) of the reference light which is selected in accordance with T SSL1 (K) of the light emitted from the light-emitting device in the main radiant direction, and a difference ΔS SSL1 (λ) of between normalized spectral power distributions are respectively defined as
S SSL1 (λ)=φ SSL1 (λ)/ Y SSL1

S ref1 (λ)=φ ref1 (λ)/ Y ref1

Δ S SSL1 (λ)= S ref1 (λ)− S SSL1 (λ), and

in a case where λ SSL1-RL-max (nm) represents a wavelength that provides a longest wavelength local maximum value of S SSL1 (λ) in a wavelength range of 380 nm or more and 780 nm or less, and when a wavelength Λ4 that is represented by S SSL1 (λ SSL1-RL-max )/2 exists on a longer wavelength-side of λ SSL1-RL-max , an index A cg (φ SSL1 (λ)) represented by the following formula (1-1) satisfies
−10.0< A cg (φ SSL1 (λ))≦120.0,

but
in a case where λ SSL1-RL-max (nm) represents a wavelength that provides the longest wavelength local maximum value of S SSL1 (λ) in a wavelength range of 380 nm or more and 780 nm or less, and when the wavelength Λ4 that is represented by S SSL1 (λ SSL1-RL-max )/2 does not exist on the longer wavelength-side of λ SSL1-RL-max ,
an index A cg (φ SSL1 (λ)) represented by the following formula (1-2) satisfies
−10.0< A cg (φ SSL1 (λ))≦120.0;

[Expression 1]
A cg (φ SSL1 (λ))=∫ 380 495 ΔS SSL1 (λ) dλ+∫ 495 590 (−Δ S SSL1 (λ)) dλ+∫ 590 Λ 4Δ S SSL1 (λ) dλ   (1-1)

[Expression 2]
A cg (φ SSL1 (λ))=∫ 380 495 ΔS SSL1 (λ) dλ+∫ 495 590 (−Δ S SSL1 (λ)) dλ+∫ 590 780 ΔS SSL1 (λ) dλ    (1-2)

Condition 2:
a distance D uv (φ SSL1 (λ)) of the spectral power distribution φ SSL1 (λ) of light from a black-body radiation locus defined by ANSI C78.377 satisfies
−0.0220≦ D uv (φ SSL1 (λ))≦−0.0070;

Condition 3:
when a maximum value of spectral intensity in a range of 430 nm or more and 495 nm or less is defined as φ SSL1-BM-max and a minimum value of spectral intensity in a range of 465 nm or more and 525 nm or less is defined as φ SSL1-BG-min , the spectral power distribution φ SSL1 (λ) of light satisfies
0.2250≦φ SSL1-BG-min /φ SSL1-BM-max ≦0.7000; and

Condition 4:
in the spectral power distribution φ SSL1 (λ) of light, when a maximum value of spectral intensity in a range of 590 nm or more and 780 nm or less is defined as φ SSL1-RM-max , a wavelength λ SSL1-RM-max that provides φ SSL1-RM-max satisfies
605 (nm)≦λ SSL1-RM-max ≦653 (nm).

2 . The light-emitting device according to claim 1 , wherein
in Condition 2,
−0.0184≦ D uv (φ SSL1 (λ))≦−0.0084 is satisfied.

3 . The light-emitting device according to claim 1 , wherein
in Condition 4,
625 (nm)≦λ SSL1-RM-max ≦647 (nm) is satisfied.

4 . The light-emitting device according to claim 1 , wherein Condition 5 below is satisfied
Condition 5:
in the spectral power distribution φ SSL1 (λ) of light, a wavelength λ SSL1-BM-max that provides φ SSL1-BM-max satisfies
430 (nm)≦λ SSL1-BM-max ≦480 (nm).

5 . The light-emitting device according to claim 1 , wherein Condition 6 below is satisfied
Condition 6:
0.1800≦φ SSL1-BG-min /φ SSL1-RM-max ≦0.8500.

6 . The light-emitting device according to claim 5 , wherein
in Condition 6,
0.1917≦φ SSL1-BG-min /φ SSL1-RM-max ≦0.7300 is satisfied.

7 . The light-emitting device according to claim 1 , wherein a luminous efficacy of radiation K SSL1 (lm/W) in a wavelength range of 380 nm or more and 780 nm or less, which is derived from φ SSL1 (λ), satisfies Condition 7
Condition 7:
210.0 lm/W≦ K SSL1 ≦290.0 lm/W.

8 . The light-emitting device according to claim 1 , wherein T SSL1 (K) satisfies Condition 8 below
Condition 8:
2600 K≦ T SSL1 ≦7700 K.

9 . The light-emitting device according to claim 1 , wherein
φ SSL1 (λ) does not have effective intensity derived from the light-emitting element in a range of 380 nm or more and 405 nm or less.

10 . The light-emitting device according to claim 1 , wherein
the blue semiconductor light-emitting element is configured such that a dominant wavelength λ CHIP-BM-dom of the blue semiconductor light-emitting element alone when pulse-driven is 445 nm or more and 475 nm or less.

11 . The light-emitting device according to claim 1 , wherein
the green phosphor is a wide-band green phosphor.

12 . The light-emitting device according to claim 1 , wherein
the green phosphor is configured such that a wavelength λ PHOS-GM-max that provides maximum emission intensity when light is excited by the green phosphor alone is 511 nm or more and 543 nm or less, and a full-width at half-maximum W PHOS-GM-fwhm thereof is 90 nm or more and 110 nm or less.

13 . The light-emitting device according to claim 1 , wherein the light-emitting device includes substantially no yellow phosphor.

14 . The light-emitting device according to claim 1 , wherein
the red phosphor is configured such that a wavelength λ PHOS-RM-max that provides maximum emission intensity when light is excited by the red phosphor alone is 622 nm or more and 663 nm or less, and a full-width at half-maximum W PHOS-RM-fwhm thereof is 80 nm or more and 105 nm or less.

15 . The light-emitting device according to claim 1 , wherein
the blue semiconductor light-emitting element is an AlInGaN light-emitting element.

16 . The light-emitting device according to claim 1 , wherein
the green phosphor is Ca 3 (Sc,Mg) 2 Si 3 O 12 :Ce (CSMS phosphor), CaSc 2 O 4 :Ce (CSO phosphor), Lu 3 Al 5 O 12 :Ce (LuAG phosphor), or Y 3 (Al,Ga) 5 O 12 :Ce (G-YAG phosphor).

17 . The light-emitting device according to claim 1 , wherein
the red phosphor includes (Sr,Ca)AlSiN 3 :Eu (SCASN phosphor), CaAlSi(ON) 3 :Eu (CASON phosphor), or CaAlSiN 3 :Eu (CASN phosphor).

18 . The light-emitting device according to claim 1 , wherein the blue semiconductor light-emitting element is an AlInGaN light-emitting element with a dominant wavelength λ CHIP-BM-dom when the blue semiconductor light-emitting element alone is pulse-driven, of 452.5 nm or more and 470 nm or less,
the green phosphor is CaSc 2 O 4 :Ce (CSO phosphor) or Lu 3 Al 5 O 12 :Ce (LuAG phosphor) with a wavelength X PHOS-GM-max that provides maximum emission intensity when light is excited by the green phosphor alone, of

Assignees

• Citizen Electronics

Inventors

• Horie Hideyoshi

Classifications

• C09K11/7769

  Oxides (C09K11/7768 takes precedence) · CPC title

• C09K11/08

  containing inorganic luminescent materials · CPC title

• C09K11/77742

  Silicates · CPC title

• C09K11/7774

  Aluminates · CPC title

• C09K11/77348

  Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides · CPC title