Light-emitting device, method for designing light-emitting device, method for driving light-emitting device, illumination method, and method for manufacturing light-emitting device

• US 9,997,678 B2
• Filed: 07/26/2017
• Issued: 06/12/2018
• Est. Priority Date: 03/04/2013
• Status: Active Grant

• Current Assignee: Citizen Electronics Company Limited
• Original Assignee: Citizen Electronics Company Limited
• Inventors: Horie, Hideyoshi
• Primary Examiner(s): NGUYEN, TUAN N
• Application Number:
  US15/660,352
• Publication Number:
  US 20170331014A1
• Time in Patent Office: 321 Days
• Field of Search: 362 831, 257 89
• CPC Class Codes: H01L 25/13 the devices being of a type provided for in group H01L33/00
• CPC Class Codes: H01L 27/15 including semiconductor components having potential barriers, specially adapted for light emission
• CPC Class Codes: H01L 33/504 Elements with two or more wavelength conversion materials
• CPC Class Codes: H01L 33/62 Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/30 Driver circuits

Abstract

An object of the present invention is to provide a light-emitting device that can implement a natural, vivid, highly visible and comfortable appearance of colors and appearance of objects as if the objects are seen outdoors, and to provide a light-emitting device that can change the appearance of colors of the illuminated objects so as to satisfy the requirements for various illuminations, and a method for designing thereof. Another object of the present invention is to improve the appearance of colors of a light-emitting device which currently exists or is in use, and which includes a semiconductor light-emitting device of which appearance of colors is not very good. Moreover, another object of the present invention is to provide a method for driving the light-emitting device, an illumination method by the device, and a method for manufacturing the light-emitting device.

These objects are achieved by the light-emitting device that incorporates light-emitting elements and satisfies predetermined requirements, in which ϕ_SSL(λ) emitted from the light-emitting device satisfies a predetermined condition.

Claims

1. A light-emitting device incorporating a light-emitting element that emits bluish purple or blue light and satisfying the following B, wherein:

ϕ

_SSL(λ

) emitted from the light-emitting device satisfies both the following Condition 1 and Condition 3′

;

B;

the light-emitting device comprises the light-emitting element and a control element, wherein

if a wavelength is denoted by λ

(nm), a spectral power distribution of a light emitted from the light-emitting element in a main radiant direction is denoted by Φ

_elm(λ

), and a spectral power distribution of a light emitted from the light-emitting device in the main radiant direction is denoted by ϕ

_SSL(λ

),

Φ

_elm(λ

) does not satisfy at least one of the following Condition 1 and Condition 3′

;

Condition 1;

light emitted from the light-emitting device includes, in the main radiant direction thereof, light whose distance D_uvSSL from a black-body radiation locus as defined by ANSI C78.377 satisfies −

0.0350≤

D_uvSSL<

0,

Condition 3′

;

if an a* value and a b* value in CIE 1976 L*a*b* color space of 15 Munsell renotation color samples from #01 to #15 listed below when mathematically assuming illumination by the target light are respectively denoted by a*_n and b*_n (where n is a natural number from 1 to

     15), and

if an a* value and a b* value in CIE 1976 L*a*b* color space of the 15 Munsell renotation color samples when mathematically assuming illumination by a reference light that is selected according to a correlated color temperature T (K) of the light emitted in the radiant direction are respectively denoted by a*_ref and b*_nref (where n is a natural number from 1 to

     15), then each saturation difference Δ

C_n satisfies

−

3.8≤

Δ

C_n≤

18.6 (where n is a natural number from 1 to

     15),

where Δ

C_n=√

{(a*_n)²+(b*_n)²}−

√

{(a*_nref)²+(b*_nref)²}

with the 15 Munsell renotation color samples being;

#01 7.5P 4/10

#02 10PB 4/10

#03 5PB 4/12

#04 7.5B 5/10

#05 10BG 6/8

#06 2.5BG 6/10

#07 2.5G 6/12

#08 7.5GY 7/10

#09 2.5GY 8/10

#10 5Y 8.5/12

#11 10YR 7/12

#12 5YR 7/12

#13 10R 6/12

#14 5R 4/14

#15 7.5RP 4/12.

2. The light-emitting device according to claim 1, wherein the light-emitting element includes a semiconductor light-emitting element that emits bluish purple or blue light.

3. The light-emitting device according to claim 1, wherein

Φ

_elm(λ

) does not satisfy the following Condition 3″

, and ϕ

_SSL(λ

) satisfies the following Condition 3″

;

Condition 3″

;

if a maximum saturation difference value is denoted by Δ

C_max and a minimum saturation difference value is denoted by Δ

C_min, then a difference |Δ

C_max−

Δ

C_min| between the maximum saturation difference value and the minimum saturation difference value satisfies

2.8≤

|Δ

C_max−

Δ

C_min|≤

19.6.

4. The light-emitting device according to claim 1, wherein

Φ

_elm(λ

) does not satisfy the following Condition 4, and ϕ

_SSL(λ

) satisfies the following Condition 4;

Condition 4;

if hue angles in CIE 1976 L*a*b* color space of the 15 Munsell renotation color samples when mathematically assuming illumination by the target light are denoted by θ

_n (degrees) (where n is a natural number from 1 to

     15), and

if hue angles in a CIE 1976 L*a*b* color space of the 15 Munsell renotation color samples when mathematically assuming illumination by a reference light that is selected according to the correlated color temperature T (K) of the light emitted in the radiant direction are denoted by θ

_nref (degrees) (where n is a natural number from 1 to

     15), then an absolute value of each difference in hue angles |Δ

h_n| satisfies

0≤

|Δ

h_n|≤

9.0 (degree) (where n is a natural number from 1 to

     15),

where Δ

h_n=θ

_n−

θ

_nref.

5. The light-emitting device according to claim 1, wherein

Φ

_elm(λ

) does not satisfy the following Condition 3′

″

, and ϕ

_SSL(λ

) satisfies the following Condition 3′

″

;

Condition 3′

″

;

an average SAT_av of saturation difference represented by formula (3) below satisfies formula (4) below;

6. The light-emitting device according to claim 5, wherein

if an average of the saturation difference derived from the spectral power distribution of the light emitted from the light-emitting element in the main radiant direction is denoted by SAT_av (Φ

_elm), and

if an average of the saturation difference derived from the spectral power distribution of the light emitted from the light-emitting device in the main radiant direction is denoted by SAT_av (ϕ

_SSL),

SAT_av (Φ

_elm)<

SAT_av (ϕ

_SSL) is satisfied.

7. The light-emitting device according to claim 1, wherein

Φ

_elm(λ

) satisfies the following Condition 3″

, and ϕ

_SSL(λ

) satisfies the following Condition 3″

;

Condition 3″

;

if a maximum saturation difference value is denoted by Δ

C_max and a minimum saturation difference value is denoted by Δ

C_min, then a difference |Δ

C_max−

Δ

C_min| between the maximum saturation difference value and the minimum saturation difference value satisfies

2.8≤

|Δ

C_max−

Δ

C_min|≤

19.6.

8. The light-emitting device according to claim 1, wherein

Φ

_elm(λ

) satisfies the following Condition 4, and ϕ

_SSL(λ

) satisfies the following Condition 4;

Condition 4;

if hue angles in CIE 1976 L*a*b* color space of the 15 Munsell renotation color samples when mathematically assuming illumination by the target light are denoted by θ

_n (degrees) (where n is a natural number from 1 to

     15), and

if hue angles in a CIE 1976 L*a*b* color space of the 15 Munsell renotation color samples when mathematically assuming illumination by a reference light that is selected according to the correlated color temperature T (K) of the light emitted in the radiant direction are denoted by θ

_nref (degrees) (where n is a natural number from 1 to

     15), then an absolute value of each difference in hue angles |Δ

h_n| satisfies

0≤

|Δ

h_n|≤

9.0 (degree) (where n is a natural number from 1 to

     15),

where Δ

h_n=θ

_n−

θ

_nref.

9. The light-emitting device according to claim 1, wherein

Φ

_elm(λ

) satisfies the following Condition 3′

″

, and ϕ

_SSL(λ

) satisfies the following Condition 3′

″

;

Condition 3′

″

;

an average SAT_av of saturation difference represented by formula (3) below satisfies formula (4) below;

10. The light-emitting device according to claim 9, wherein

if an average of the saturation difference derived from the spectral power distribution of the light emitted from the light-emitting element in the main radiant direction is denoted by SAT_av (Φ

_elm), and

if an average of the saturation difference derived from the spectral power distribution of the light emitted from the light-emitting device in the main radiant direction is denoted by SAT_av (ϕ

_SSL),

SAT_av(Φ

_elm)<

SAT_av (ϕ

_SSL) is satisfied.

11. The light-emitting device according to claim 1, wherein

if D_uv derived from the spectral power distribution of the light emitted from the light-emitting element in the main radiant direction is denoted by D_uv (Φ

_elm), and D_uv derived from the spectral power distribution of the light emitted from the light-emitting device in the main radiant direction is denoted by D_uv (ϕ

_SSL),

D_uv(ϕ

_SSL)<

D_uv(Φ

_elm) is satisfied.

12. The light-emitting device according to claim 1, wherein the control element is an optical filter that absorbs or reflects light in a range of 380 nm≤

λ

(nm)≤

780 nm.

13. The light-emitting device according to claim 1, wherein the control element has a collection function, a diffusion function, or both, of the light emitted from the light-emitting element.

14. The light-emitting device according to claim 1, wherein the collection function, the diffusion function, or both of the control element is implemented by at least one of the functions of a concave lens, a convex lens and a Fresnel lens.

15. The light-emitting device according to claim 1, wherein a luminous efficacy of radiation K (lm/W) in a wavelength range from 380 nm to 780 nm as derived from the spectral power distribution φ

_SSL(λ

) of light emitted from the light-emitting device in the radiant direction satisfies

180 (lm/W)≤

K(lm/W)≤

320 (lm/W).

16. The light-emitting device according to claim 1, wherein the correlated color temperature T(K) of the light-emitting device satisfies

2550(K)≤

T(K)≤

7000(K).

17. The light-emitting device according to claim 1, wherein illuminance at which the light emitted from the light-emitting device in the radiant direction illuminates objects is 150 lx to 5000 lx.

18. The light-emitting device according to claim 1, wherein the light-emitting device emits, in the radiant direction, light emitted from one to six light-emitting elements.

19. The light-emitting device according to claim 1, wherein a peak wavelength of an emission spectrum of the light-emitting element is 380 nm or longer and shorter than 495 nm and the full-width at half-maximum of the emission spectrum of the light-emitting element is 2 nm to 45 nm.

20. The light-emitting device according to claim 19, wherein the peak wavelength of the emission spectrum of the light-emitting element is 395 nm or longer and shorter than 420 nm.

21. The light-emitting device according to claim 19, wherein the peak wavelength of the emission spectrum of the light-emitting element is 420 nm or longer and shorter than 455 nm.

22. The light-emitting device according to claim 19, wherein the peak wavelength of the emission spectrum of the light-emitting element is 455 nm or longer and shorter than 485 nm.

23. The light-emitting device according to claim 1, wherein the peak wavelength of the emission spectrum of the light-emitting element is 495 nm or longer and shorter than 590 nm and the full-width at half-maximum of the emission spectrum of the light-emitting element is 2 nm to 75 nm.

24. The light-emitting device according to claim 1, wherein the peak wavelength of the emission spectrum of the light-emitting element is 590 nm or longer and shorter than 780 nm and the full-width at half-maximum of the emission spectrum of the light-emitting element is 2 nm to 30 nm.

25. The light-emitting device according to claim 1, comprising a phosphor as a light-emitting element.

26. The light-emitting device according to claim 25, wherein the phosphor includes one to five types of phosphors each having different emission spectra.

27. The light-emitting device according to claim 25, wherein the phosphor includes a phosphor having an individual emission spectrum, when photoexcited at room temperature, with a peak wavelength of 380 nm or longer and shorter than 495 nm and a full-width at half-maximum of 2 nm to 90 nm.

28. The light-emitting device according to claim 27, wherein the phosphor includes one or more types of phosphors selected from the group consisting of a phosphor represented by general formula (5) below, a phosphor represented by general formula (5)′

below, (Sr,Ba)₃MgSi₂O₈;

Eu²⁺, and (Ba,Sr,Ca,Mg)Si₂O₂N₂;

Eu

(Ba,Sr,Ca)MgAl₁₀O₁₇;

Mn,Eu 

 

(5)

Sr_aBa_bEu_x(PO₄)_cX_d 

 

(5)′

(in the general formula (5)′

, X is Cl, in addition, c, d, and x are numbers satisfying 2.7≤

c≤

3.3, 0.9≤

d≤

1.1, and 0.3≤

x≤

1.2, moreover, a and b satisfy conditions represented by a+b=5−

x and 0≤

b/(a+b)≤

0.6).

29. The light-emitting device according to claim 25, wherein the phosphor includes a phosphor having an individual emission spectrum, when photoexcited at room temperature, with a peak wavelength of 495 nm or longer and shorter than 590 nm and a full-width at half-maximum of 2 to 130 nm.

30. The light-emitting device according to claim 29, wherein the phosphor includes one or more types of phosphors selected from the group consisting of Si₆₋

xAl_zO_zN<sub>8−

z</sub>;

Eu (where 0<

z<

4.2), a phosphor represented by general formula (6) below, a phosphor represented by general formula (6)′

below, and SrGaS₄;

Eu²⁺

Ba_aCa_bSr_eMg_dEu_xSiO₄ 

 

(6)

(in the general formula (6), a, b, c, d, and x satisfy a+b+c+d+x=2, 1.0≤

a≤

2.0, 0≤

b<

0.2, 0.2≤

c≤

1.0, 0≤

d<

0.2, and 0<

x≤

0.5),

Ba<sub>1−

x−

y</sub>Sr_xEu_yMg<sub>1−

z</sub>Mn_zAl₁₀O₁₇ 

 

(6)′

(in the general formula (6)′

, x, y, and z respectively satisfy 0.1≤

x≤

0.4, 0.25≤

y≤

0.6, and 0.05≤

z≤

0.5).

31. The light-emitting device according to claim 25, wherein the phosphor includes a phosphor having an individual emission spectrum, when photoexcited at room temperature, with a peak wavelength of 590 nm or longer and shorter than 780 nm and a full-width at half-maximum of 2 nm to 130 nm.

32. The light-emitting device according to claim 31, wherein the phosphor includes one or more types of phosphors selected from the group consisting of a phosphor represented by general formula (7) below, a phosphor represented by general formula (7)′

below, (Sr,Ca,Ba)₂Al_xSi<sub>5−

x</sub>O_xN<sub>8−

x</sub>;

Eu (where 0≤

x≤

2), Eu_y(Sr,Ca,Ba)<sub>1−

y</sub>;

Al_1+xSi<sub>4−

x</sub>O_xN<sub>7−

x</sub> (where 0≤

x<

4, 0≤

y<

0.2), K₂SiF₆;

Mn⁴⁺, A_2+xM_yMn_zF_n (where A is Na and/or K;

M is Si and Al;

−

1≤

x<

1 and 0.9≤

y+z≤

1.1 and 0.001≤

z≤

0.4 and 5≤

n≤

7), (Ca,Sr,Ba,Mg)AlSiN₃;

Eu and/or (Ca,Sr,Ba)AlSiN₃;

Eu, and (CaAlSiN₃)<sub>1−

x</sub>(Si₂N₂O)_x;

Eu (where x satisfies 0<

x<

0.5)

(La<sub>1−

x−

y</sub>Eu_xLn_y)₂O₂S 

 

(7)

(in the general formula (7), x and y denote numbers respectively satisfying 0.02≤

x≤

0.50 and 0≤

y≤

0.50, and Ln denotes at least one trivalent rare-earth element among Y, Gd, Lu, Sc, Sm, and Er)

(k−

x)MgO.xAF₂.GeO₂;

yMn⁴⁺ 

 

(7)′

(in the general formula (7)′

, k, x, and y denote numbers respectively satisfying 2.8≤

k≤

5, 0.1≤

x≤

0.7, and 0.005≤

y≤

0.015, and A is calcium (Ca), strontium (Sr), barium (Ba), zinc (Zn), or a mixture consisting of these elements).

36. The light-emitting device according to claim 1, wherein

Φ

_elm(λ

) does not satisfy the following Condition 4, and ϕ

_SSL(λ

) satisfies the following Condition 4;

Condition 4;

if hue angles in CIE 1976 L*a*b* color space of the 15 Munsell renotation color samples when mathematically assuming illumination by the target light are denoted by θ

_n (degrees) (where n is a natural number from 1 to

     15), and

if hue angles in a CIE 1976 L*a*b* color space of the 15 Munsell renotation color samples when mathematically assuming illumination by a reference light that is selected according to the correlated color temperature T (K) of the light emitted in the radiant direction are denoted by θ

_nref (degrees) (where n is a natural number from 1 to

     15), then an absolute value of each difference in hue angles |Δ

h_n| satisfies

0≤

|Δ

h_n|≤

9.0 (degree) (where n is a natural number from 1 to

     15),

where Δ

h_n=θ

_n−

θ

_nref.

37. The light-emitting device according to claim 1, wherein

Φ

_elm(λ

) does not satisfy the following Condition 3′

″

, and ϕ

_SSL(λ

) satisfies the following Condition 3′

″

;

Condition 3′

″

;

an average SAT_av of saturation difference represented by formula (3) below satisfies formula (4) below;

38. The light-emitting device according to claim 37, wherein

if an average of the saturation difference derived from the spectral power distribution of the light emitted from the light-emitting element in the main radiant direction is denoted by SAT_av (Φ

_elm), and

if an average of the saturation difference derived from the spectral power distribution of the light emitted from the light-emitting device in the main radiant direction is denoted by SAT_av (φ

_SSL),

SAT_av(Φ

_elm)<

SAT_av(ϕ

_SSL) is satisfied.

33. A light-emitting device incorporating a light-emitting element that emits bluish purple or blue light and satisfying the following B, wherein

ϕ

_SSL(λ

) emitted from the light-emitting device satisfies both the following Condition 1 and Condition 3′

;

B;

the light-emitting device comprises the light-emitting element and a control element, wherein

if a wavelength is denoted by λ

(nm), a spectral power distribution of a light emitted from the light-emitting element in a main radiant direction is denoted by Φ

_elm(λ

), and a spectral power distribution of a light emitted from the light-emitting device in the main radiant direction is denoted by ϕ

_SSL(λ

),

Φ

_elm(λ

) satisfies both the following Condition 1 and Condition 3′

;

Condition 1;

light emitted from the light-emitting device includes, in the main radiant direction thereof, light whose distance D_uvSSL from a black-body radiation locus as defined by ANSI C78.377 satisfies −

0.0350≤

D_uvSSL<

0,

Condition 3′

;

if an a* value and a b* value in CIE 1976 L*a*b* color space of 15 Munsell renotation color samples from #01 to #15 listed below when mathematically assuming illumination by the target light are respectively denoted by a*_n and b*_n (where n is a natural number from 1 to

     15), and

if an a* value and a b* value in CIE 1976 L*a*b* color space of the 15 Munsell renotation color samples when mathematically assuming illumination by a reference light that is selected according to a correlated color temperature T (K) of the light emitted in the radiant direction are respectively denoted by a*_nref and b*_nref (where n is a natural number from 1 to

     15), then each saturation difference Δ

C_n satisfies

−

3.8≤

Δ

C_n≤

18.6 (where n is a natural number from 1 to

     15),

where Δ

C_n=√

{(a*_n)²+(b*_n)²}−

√

{(a*_nref)²+(b*_nref)²}

with the 15 Munsell renotation color samples being;

#01 7.5P 4/10

#02 10PB 4/10

#03 5PB 4/12

#04 7.5B 5/10

#05 10BG 6/8

#06 2.5BG 6/10

#07 2.5G 6/12

#08 7.5GY 7/10

#09 2.5GY 8/10

#10 5Y 8.5/12

#11 10YR 7/12

#12 5YR 7/12

#13 10R 6/12

#14 5R 4/14

#15 7.5RP 4/12.

34. The light-emitting device according to claim 33, wherein the light-emitting element includes a semiconductor light-emitting element that emits bluish purple or blue light.

35. The light-emitting device according to claim 33, wherein

φ

_elm(λ

) does not satisfy the following Condition 3″

, and ϕ

_SSL(λ

) satisfies the following Condition 3″

;

Condition 3″

;

if a maximum saturation difference value is denoted by Δ

C_max and a minimum saturation difference value is denoted by Δ

C_min, then a difference |Δ

C_max−

Δ

C_min| between the maximum saturation difference value and the minimum saturation difference value satisfies

2.8≤

|Δ

C_max−

Δ

C_min|≤

19.6.

39. The light-emitting device according to claim 33, wherein

Φ

_elm(λ

) satisfies the following Condition 3″

, and ϕ

_SSL(λ

) satisfies the following Condition 3″

;

Condition 3″

;

if a maximum saturation difference value is denoted by Δ

C_max and a minimum saturation difference value is denoted by Δ

C_min, then a difference |Δ

C_max−

Δ

C_min| between the maximum saturation difference value and the minimum saturation difference value satisfies

2.8≤

|Δ

C_max−

Δ

C_min|≤

19.6.

40. The light-emitting device according to claim 33, wherein

Φ

_elm(λ

) satisfies the following Condition 4, and ϕ

_SSL(λ

) satisfies the following Condition 4;

Condition 4;

if hue angles in CIE 1976 L*a*b* color space of the 15 Munsell renotation color samples when mathematically assuming illumination by the target light are denoted by θ

_n (degrees) (where n is a natural number from 1 to

     15), and

if hue angles in a CIE 1976 L*a*b* color space of the 15 Munsell renotation color samples when mathematically assuming illumination by a reference light that is selected according to the correlated color temperature T (K) of the light emitted in the radiant direction are denoted by θ

_nref (degrees) (where n is a natural number from 1 to

     15), then an absolute value of each difference in hue angles |Δ

h_n| satisfies

0≤

|Δ

h_n|≤

9.0 (degree) (where n is a natural number from 1 to

     15),

where Δ

h_n=θ

_n−

θ

_nref.

41. The light-emitting device according to claim 33, wherein

Φ

_elm(λ

) satisfies the following Condition 3′

″

, and ϕ

_SSL(λ

) satisfies the following Condition 3′

″

;

Condition 3′

″

;

an average SAT_av of saturation difference represented by formula (3) below satisfies formula (4) below;

42. The light-emitting device according to claim 41, wherein

if an average of the saturation difference derived from the spectral power distribution of the light emitted from the light-emitting element in the main radiant direction is denoted by SAT_av(Φ

_elm), and

if an average of the saturation difference derived from the spectral power distribution of the light emitted from the light-emitting device in the main radiant direction is denoted by SAT_av (ϕ

_SSL),

SAT_av(Φ

_elm)<

SAT_av(ϕ

_SSL) is satisfied.

43. The light-emitting device according to claim 33, wherein

if D_uv derived from the spectral power distribution of the light emitted from the light-emitting element in the main radiant direction is denoted by D_uv (Φ

_elm), and D_uv derived from the spectral power distribution of the light emitted from the light-emitting device in the main radiant direction is denoted by D_uv (ϕ

_SSL),

D_uv(ϕ

_SSL)<

D_uv(Φ

_elm) is satisfied.

44. The light-emitting device according to claim 33, wherein the control element is an optical filter that absorbs or reflects light in a range of 380 nm≤

λ

(nm)≤

780 nm.

45. The light-emitting device according to claim 33, wherein the control element has a collection function, a diffusion function, or both, of the light emitted from the light-emitting element.

46. The light-emitting device according to claim 45, wherein the collection function, the diffusion function, or both of the control element is implemented by at least one of the functions of a concave lens, a convex lens and a Fresnel lens.

47. The light-emitting device according to claim 33, wherein a luminous efficacy of radiation K (lm/W) in a wavelength range from 380 nm to 780 nm as derived from the spectral power distribution φ

_SSL (λ

) of light emitted from the light-emitting device in the radiant direction satisfies

180 (lm/W)≤

K(lm/W)≤

320 (lm/W).

48. The light-emitting device according to claim 33, wherein the correlated color temperature T(K) of the light-emitting device satisfies

2550(K)≤

T(K)≤

7000(K).

49. The light-emitting device according to claim 33, wherein illuminance at which the light emitted from the light-emitting device in the radiant direction illuminates objects is 150 lx to 5000 lx.

50. The light-emitting device according to claim 33, wherein the light-emitting device emits, in the radiant direction, light emitted from one to six light-emitting elements.

51. The light-emitting device according to claim 33, wherein a peak wavelength of an emission spectrum of the light-emitting element is 380 nm or longer and shorter than 495 nm and the full-width at half-maximum of the emission spectrum of the light-emitting element is 2 nm to 45 nm.

52. The light-emitting device according to claim 51, wherein the peak wavelength of the emission spectrum of the light-emitting element is 395 nm or longer and shorter than 420 nm.

53. The light-emitting device according to claim 51, wherein the peak wavelength of the emission spectrum of the light-emitting element is 420 nm or longer and shorter than 455 nm.

54. The light-emitting device according to claim 51, wherein the peak wavelength of the emission spectrum of the light-emitting element is 455 nm or longer and shorter than 485 nm.

55. The light-emitting device according to claim 33, wherein the peak wavelength of the emission spectrum of the light-emitting element is 495 nm or longer and shorter than 590 nm and the full-width at half-maximum of the emission spectrum of the light-emitting element is 2 nm to 75 nm.

56. The light-emitting device according to claim 33, wherein the peak wavelength of the emission spectrum of the light-emitting element is 590 nm or longer and shorter than 780 nm and the full-width at half-maximum of the emission spectrum of the light-emitting element is 2 nm to 30 nm.

57. The light-emitting device according to claim 33, comprising a phosphor as a light-emitting element.

58. The light-emitting device according to claim 57, wherein the phosphor includes one to five types of phosphors each having different emission spectra.

59. The light-emitting device according to claim 57, wherein the phosphor includes a phosphor having an individual emission spectrum, when photoexcited at room temperature, with a peak wavelength of 380 nm or longer and shorter than 495 nm and a full-width at half-maximum of 2 nm to 90 nm.

60. The light-emitting device according to claim 59, wherein

the phosphor includes one or more types of phosphors selected from the group consisting of a phosphor represented by general formula (5) below, a phosphor represented by general formula (5)′

below, (Sr,Ba)₃MgSi₂O₈;

Eu²⁺, and (Ba,Sr,Ca,Mg)Si₂O₂N₂;

Eu

(Ba,Sr,Ca)MgAl₁₀O₁₇;

Mn,Eu 

 

(5)

Sr_aBa_bEu_x(PO₄)_cX_d 

 

(5)′

(in the general formula (5)′

, X is Cl, in addition, c, d, and x are numbers satisfying 2.7≤

c≤

3.3, 0.9≤

d≤

1.1, and 0.3≤

x≤

1.2, moreover, a and b satisfy conditions represented by a+b=5−

x and 0≤

b/(a+b)≤

0.6).

61. The light-emitting device according to claim 57, wherein the phosphor includes a phosphor having an individual emission spectrum, when photoexcited at room temperature, with a peak wavelength of 495 nm or longer and shorter than 590 nm and a full-width at half-maximum of 2 to 130 nm.

62. The light-emitting device according to claim 61, wherein

the phosphor includes one or more types of phosphors selected from the group consisting of Si₆₋

zAl_zO_zN<sub>8−

z</sub>;

Eu (where 0<

z<

4.2), a phosphor represented by general formula (6) below, a phosphor represented by general formula (6)′

below, and SrGaS₄;

Eu²⁺

Ba_aCa_bSr_eMg_dEu_xSiO₄ 

 

(6)

(in the general formula (6), a, b, c, d, and x satisfy a +b+c+d+x=2, 1.0≤

a≤

2.0, 0≤

b<

0.2, 0.2≤

c≤

1.0, 0≤

d<

0.2, and 0<

x≤

0.5),

Ba<sub>1−

x−

y</sub>Sr_xEu_yMg<sub>1−

z</sub>Mn_zAl₁₀O₁₇ 

 

(6)′

(in the general formula (6)′

, x, y, and z respectively satisfy 0.1≤

x≤

0.4, 0.25≤

y≤

0.6, and 0.05≤

z≤

0.5).

63. The light-emitting device according to claim 57, wherein the phosphor includes a phosphor having an individual emission spectrum, when photoexcited at room temperature, with a peak wavelength of 590 nm or longer and shorter than 780 nm and a full-width at half-maximum of 2 nm to 130 nm.

64. The light-emitting device according to claim 63, wherein

the phosphor includes one or more types of phosphors selected from the group consisting of a phosphor represented by general formula (7) below, a phosphor represented by general formula (7)′

below, (Sr,Ca,Ba)₂Al_xSi<sub>5−

x</sub>O_xN<sub>8−

x</sub>;

Eu (where 0≤

x≤

2), Eu_y(Sr,Ca,Ba)<sub>1−

y</sub>;

Al_1+xSi<sub>4−

x</sub>O_xN<sub>7−

x</sub> (where 0≤

x≤

4, 0≤

y<

0.2), K₂SiF₆;

Mn⁴⁺, A_2+xM_yMn_zF_n (where A is Na and/or K;

M is Si and Al;

−

1≤

x≤

1 and 0.9≤

y+z≤

1.1 and 0.001≤

z≤

0.4 and 5≤

n≤

7), (Ca,Sr,Ba,Mg)AlSiN₃;

Eu and/or (Ca,Sr,Ba)AlSiN₃;

Eu, and (CaAlSiN₃)<sub>1−

x</sub>(Si₂N₂O)_x;

Eu (where x satisfies 0<

x<

0.5)

(La<sub>1−

x−

y</sub>Eu_xLn_y)₂O₂S 

 

(7)

(in the general formula (7), x and y denote numbers respectively satisfying 0.02≤

x≤

0.50 and 0≤

y≤

0.50, and Ln denotes at least one trivalent rare-earth element among Y, Gd, Lu, Sc, Sm, and Er)

(k−

x)MgO.xAF₂.GeO₂;

yMn⁴⁺ 

 

(7)′

(in the general formula (7)′

, k, x, and y denote numbers respectively satisfying 2.8≤

k≤

5, 0.1≤

x≤

0.7, and 0.005≤

y≤

0.015, and A is calcium (Ca), strontium (Sr), barium (Ba), zinc (Zn), or a mixture consisting of these elements).

65. An illumination method, comprising illuminating an object by light emitted from at least one light-emitting device comprising a light-emitting element, that emits bluish purple or blue light, and a control element,

wherein:

in the illumination step,

when light emitted from the light-emitting element illuminates the object, the object is illuminated such that target light measured at a position of the object does not satisfy at least any one of <

1> and

<

2′

>

below, and

when light emitted from the at least one light-emitting device illuminates the object, the object is illuminated such that the target light measured at a position of the object satisfies both <

1> and

<

2′

>

below;

<

1>

;

a distance D_uvSSL from a black-body radiation locus as defined by ANSI C78.377 of the target light measured at the position of the object satisfies −

0.0350≤

D_uv<

0;

<

2′

>

;

if an a* value and a b* value in CIE 1976 L*a*b* color space of 15 Munsell renotation color samples from #01 to #15 listed below when mathematically assuming illumination by the target light measured at the position of the object are respectively denoted by a*_n and b*_n (where n is a natural number from 1 to

     15), and

if an a* value and a b* value in CIE 1976 L*a*b* color space of the 15 Munsell renotation color samples when mathematically assuming illumination by a reference light that is selected according to a correlated color temperature T (K) of the target light measured at the position of the object are respectively denoted by a*_nref and b*_nref (where n is a natural number from 1 to

     15), then each saturation difference Δ

C_n satisfies

−

3.8≤

Δ

C_n≤

18.6 (where n is a natural number from 1 to

     15),

where Δ

C_n=√

{(a*_n)²+(b*_n)²}−

√

{(a*_nref)²+(b*_nref)²}

with the 15 Munsell renotation color samples being;

#01 7.5P 4/10

#02 10PB 4/10

#03 5PB 4/12

#04 7.5B 5/10

#05 10BG 6/8

#06 2.5BG 6/10

#07 2.5G 6/12

#08 7.5GY 7/10

#09 2.5GY 8/10

#10 5Y 8.5/12

#11 10YR 7/12

#12 5YR 7/12

#13 10R 6/12

#14 5R 4/14

#15 7.5RP 4/12.

66. The illumination method according to claim 65, wherein

when the light emitted from the light-emitting element illuminates the object, the object is illuminated such that the target light measured at the position of the object does not satisfy the following Condition <

2″

>

, and

when the light emitted from the at least one light-emitting device illuminates the object, the object is illuminated such that the target light measured at the position of the object satisfies the following Condition <

2″

>

;

Condition <

2″

>

;

if a maximum saturation difference value is denoted by Δ

C_max and a minimum saturation difference value is denoted by Δ

C_min, then a difference |Δ

C_max−

Δ

C_min| between the maximum saturation difference value and the minimum saturation difference value satisfies

2.8≤

|Δ

C_max−

Δ

C_min|≤

19.6.

67. The illumination method according to claim 65, wherein

when the light emitted from the light-emitting element illuminates the object, the object is illuminated such that the target light measured at the position of the object does not satisfy the following Condition <

3>

, and

when the light emitted from the at least one light-emitting device illuminates the object, the object is illuminated such that the target light measured at the position of the object satisfies the following Condition <

3>

;

<

3>

;

if hue angles in CIE 1976 L*a*b* color space of the 15 Munsell renotation color samples when mathematically assuming illumination by the target light measured at the position of the object are denoted by θ

_n (degrees) (where n is a natural number from 1 to

     15), and

if hue angles in CIE 1976 L*a*b* color space of the 15 Munsell renotation color samples when mathematically assuming illumination by a reference light that is selected according to the correlated color temperature T (K) of the target light measured at the position of the object are denoted by θ

_nref (degrees) (where n is a natural number from 1 to

     15), then an absolute value of each difference in hue angles |Δ

h_n| satisfies

0≤

|Δ

h_n|≤

9.0 (degree) (where n is a natural number from 1 to

     15),

where Δ

h_n=θ

_n—

θ

_nref.

68. The illumination method according to claim 65, wherein

when the light emitted from the light-emitting element illuminates the object, the object is illuminated such that the target light measured at the position of the object does not satisfy the following Condition <

2′

″

>

, and

when the light emitted from the at least one light-emitting device illuminates the object, the object is illuminated such that the target light measured at the position of the object satisfies the following Condition <

2′

″

>

;

<

2′

″

>

an average SAT_av of saturation difference represented by formula (3) below satisfies formula (4) below;

69. The illumination method according to claim 65, wherein

when the light emitted from the light-emitting element illuminates the object, the object is illuminated such that the target light measured at the position of the object satisfies the following Condition <

2″

>

, and

when the light emitted from the at least one light-emitting device illuminates the object, the object is illuminated such that the target light measured at the position of the object satisfies the following Condition <

2″

>

;

Condition <

2″

>

;

if a maximum saturation difference value is denoted by Δ

C_max and a minimum saturation difference value is denoted by Δ

C_min, then a difference |Δ

C_max−

Δ

C_min| between the maximum saturation difference value and the minimum saturation difference value satisfies

2.8≤

|Δ

C_max−

Δ

C_min|≤

19.6.

70. The illumination method according to claim 65, wherein

when the light emitted from the light-emitting element illuminates the object, the object is illuminated such that the target light measured at the position of the object satisfies the following Condition <

3>

, and

when the light emitted from the at least one light-emitting device illuminates the object, the object is illuminated such that the target light measured at the position of the object satisfies the following Condition <

3>

;

<

3>

;

if hue angles in CIE 1976 L*a*b* color space of the 15 Munsell renotation color samples when mathematically assuming illumination by the target light measured at the position of the object are denoted by θ

_n (degrees) (where n is a natural number from 1 to

     15), and

if hue angles in CIE 1976 L*a*b* color space of the 15 Munsell renotation color samples when mathematically assuming illumination by a reference light that is selected according to the correlated color temperature T (K) of the target light measured at the position of the object are denoted by θ

_nref (degrees) (where n is a natural number from 1 to

     15), then an absolute value of each difference in hue angles |Δ

h_n| satisfies

0≤

|Δ

h_n|≤

9.0 (degree) (where n is a natural number from 1 to

     15),

where Δ

h_n=θ

_n−

θ

_nref.

71. The illumination method according to claim 65, wherein

when the light emitted from the light-emitting element illuminates the object, the object is illuminated such illuminated that the target light measured at the position of the object satisfies the following Condition <

2′

″

>

, and

when the light emitted from the at least one light-emitting device illuminates the object, the object is illuminated such that the target light measured at the position of the object satisfies the following Condition <

2′

″

>

;

<

2′

″

>

an average SAT_av of saturation difference represented by formula (3) below satisfies formula (4) below;

72. The illumination method according to claim 65, wherein the light-emitting element includes semiconductor light-emitting element that emits bluish purple or blue light.

73. An illumination method, comprising illuminating an object by light emitted from at least one light-emitting device comprising a light-emitting element, that emits bluish purple or blue light, and a control element,

wherein:

in the illumination step,

when light emitted from the light-emitting element illuminates the object, the object is illuminated such that target light measured at a position of the object satisfies both <

1> and

<

2′

>

below, and

when light emitted from the at least one light-emitting device illuminates the object, the object is illuminated such that the target light measured at a position of the object satisfies both <

1> and

<

2′

>

below;

<

1>

;

a distance D_uvSSL from a black-body radiation locus as defined by ANSI C78.377 of the target light measured at the position of the object satisfies −

0.0350≤

D_uv≤

0;

<

2′

>

;

if an a* value and a b* value in CIE 1976 L*a*b* color space of 15 Munsell renotation color samples from #01 to #15 listed below when mathematically assuming illumination by the target light measured at the position of the object are respectively denoted by a*_n and b*_n (where n is a natural number from 1 to

     15), and

if an a* value and a b* value in CIE 1976 L*a*b* color space of the 15 Munsell renotation color samples when mathematically assuming illumination by a reference light that is selected according to a correlated color temperature T (K) of the target light measured at the position of the object are respectively denoted by a*_nref and b*_nref (where n is a natural number from 1 to

     15), then each saturation difference Δ

C_n satisfies

−

3.8≤

Δ

C_n≤

18.6 (where n is a natural number from 1 to

     15),

where Δ

C_n=√

{(a*_n)²+(b*_n)²}−

√

{(a*_nref)²+(b*_nref)²}

with the 15 Munsell renotation color samples being;

#01 7.5P 4/10

#02 10PB 4/10

#03 5PB 4/12

#04 7.5B 5/10

#05 10BG 6/8

#06 2.5BG 6/10

#07 2.5G 6/12

#08 7.5GY 7/10

#09 2.5GY 8/10

#10 5Y 8.5/12

#11 10YR 7/12

#12 5YR 7/12

#13 10R 6/12

#14 5R 4/14

#15 7.5RP 4/12.

74. The illumination method according to claim 73, wherein

when the light emitted from the light-emitting element illuminates the object, the object is illuminated such that the target light measured at the position of the object does not satisfy the following Condition

<

2″

>

, and

when the light emitted from the at least one light-emitting device illuminates the object, the object is illuminated such that the target light measured at the position of the object satisfies the following Condition <

2″

>

;

Condition <

2″

>

;

if a maximum saturation difference value is denoted by Δ

C_max and a minimum saturation difference value is denoted by Δ

C_min, then a difference |Δ

C_max−

Δ

C_min| between the maximum saturation difference value and the minimum saturation difference value satisfies

2.8≤

|Δ

C_max−

Δ

C_min|≤

19.6.

75. The illumination method according to claim 73, wherein

when the light emitted from the light-emitting element illuminates the object, the object is illuminated such that the target light measured at the position of the object does not satisfy the following Condition <

3>

, and

when the light emitted from the at least one light-emitting device illuminates the object, the object is illuminated such that the target light measured at the position of the object satisfies the following Condition <

3>

;

<

3>

;

if hue angles in CIE 1976 L*a*b* color space of the 15 Munsell renotation color samples when mathematically assuming illumination by the target light measured at the position of the object are denoted by θ

_n (degrees) (where n is a natural number from 1 to

     15), and

if hue angles in CIE 1976 L*a*b* color space of the 15 Munsell renotation color samples when mathematically assuming illumination by a reference light that is selected according to the correlated color temperature T (K) of the target light measured at the position of the object are denoted by θ

_nref (degrees) (where n is a natural number from 1 to

     15), then an absolute value of each difference in hue angles |Δ

h_n| satisfies

0≤

|Δ

h_n|≤

9.0 (degree) (where n is a natural number from 1 to

     15),

where Δ

h_n=θ

_n−

θ

_nref.

76. The illumination method according to claim 73, wherein

when the light emitted from the light-emitting element illuminates the object, the object is illuminated such that the target light measured at the position of the object does not satisfy the following Condition <

2′

″

>

, and

when the light emitted from the at least one light-emitting device illuminates the object, the object is illuminated such that the target light measured at the position of the object satisfies the following Condition <

2′

″

>

;

<

2′

″

>

an average SAT_av of saturation difference represented by formula (3) below satisfies formula (4) below;

77. The illumination method according to claim 73, wherein

when the light emitted from the light-emitting element illuminates the object, the object is illuminated such that the target light measured at the position of the object satisfies the following Condition <

2″

>

, and

when the light emitted from the at least one light-emitting device illuminates the object, the object is illuminated such that the target light measured at the position of the object satisfies the following Condition <

2″

>

;

Condition <

2″

>

;

if a maximum saturation difference value is denoted by Δ

C_max and a minimum saturation difference value is denoted by Δ

C_min, then a difference |Δ

C_max−

Δ

C_min| between the maximum saturation difference value and the minimum saturation difference value satisfies

2.8≤

|Δ

C_max−

Δ

C_min|≤

19.6.

78. The illumination method according to claim 73, wherein

when the light emitted from the light-emitting element illuminates the object, the object is illuminated such that the target light measured at the position of the object satisfies the following Condition <

3>

, and

when the light emitted from the at least one light-emitting device illuminates the object, the object is illuminated such that the target light measured at the position of the object satisfies the following Condition <

3>

;

<

3>

;

if hue angles in CIE 1976 L*a*b* color space of the 15 Munsell renotation color samples when mathematically assuming illumination by the target light measured at the position of the object are denoted by θ

_n (degrees) (where n is a natural number from 1 to

     15), and

if hue angles in CIE 1976 L*a*b* color space of the 15 Munsell renotation color samples when mathematically assuming illumination by a reference light that is selected according to the correlated color temperature T (K) of the target light measured at the position of the object are denoted by θ

_nref (degrees) (where n is a natural number from 1 to

     15), then an absolute value of each difference in hue angles |Δ

h_n| satisfies

0≤

|Δ

h_n|≤

9.0 (degree) (where n is a natural number from 1 to

     15),

where Δ

h_n=θ

_n−

θ

_nref.

79. The illumination method according to claim 73, wherein

when the light emitted from the light-emitting element illuminates the object, the object is illuminated such that the target light measured at the position of the object satisfies the following Condition <

2′

″

>

, and

when the light emitted from the at least one light-emitting device illuminates the object, the object is illuminated such that the target light measured at the position of the object satisfies the following Condition <

2′

″

>

;

<

2′

″

>

an average SAT_av of saturation difference represented by formula (3) below satisfies formula (4) below;

80. The illumination method according to claim 73, wherein the light-emitting element includes a semiconductor light-emitting element that emits bluish purple or blue light.