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 9,755,118 B2
• Filed: 09/15/2016
• Issued: 09/05/2017
• 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:
  US15/266,592
• Publication Number:
  US 20170005240A1
• Time in Patent Office: 355 Days
• Field of Search: 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 which includes M number of light-emitting areas (M is 2 or greater natural number) and has light-emitting elements in the light-emitting areas, wherein

when φ

_SSL(λ

) (N is 1 to M) is a spectral power distribution of a light emitted from each light emitting area in a main radiant direction of the light-emitting device, and φ

_SSL(λ

), which is a spectral power distribution of all the lights emitted from the light-emitting device in the radiant direction, is represented by

2. The light-emitting device according to claim 1, including the light emitting areas that allow φ

_SSL(λ

) to further satisfy the following Condition 3″

by changing a luminous flux amount and/or a radiant flux amount emitted from the light emitting areas;

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.

3. The light-emitting device according to claim 1, including the light emitting areas that allow φ

_SSL(λ

) to further satisfy the following Condition 4 by changing a luminous flux amount and/or a radiant flux amount emitted from the light emitting areas;

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 light emitted in the radiant direction are denoted by θ

_nSSL (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_SSL (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

_nSSL−

θ

_nref.

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

a semiconductor light-emitting element is included in at least one of the light emitting areas as the light-emitting element.

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

the peak wavelength of the emission spectrum of the semiconductor light-emitting element is 420 nm or longer and shorter than 455 nm.

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

the peak wavelength of the emission spectrum of the semiconductor light-emitting element is 455 nm or longer and shorter than 485 nm.

7. The light-emitting device according to claim 1, including light emitting areas so that φ

_SSL(λ

) can satisfy the Condition 1′ and

Condition 3′

by changing a luminous flux amount and/or a radiant flux amount emitted from the light emitting areas.

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

all of φ

_SSLN(λ

) (N is 1 to M) satisfies the Condition 1′ and

Condition 3′

.

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

at least one light emitting area of the M number of light emitting areas has wiring that allows the light emitting area to be electrically driven independently from other light emitting areas.

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

all the M numbers of light emitting areas each have wiring that allows the light emitting area to be electrically driven independently from other light emitting areas.

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

at least one selected from the group consisting of the correlated color temperature T_SSL(K) and the distance D_uvSSL from the black-body radiation locus can be changed.

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

a luminous flux and/or a radiant flux emitted from the light-emitting device in the main radiant direction can be independently controlled when at least one selected from the group consisting of the correlated color temperature T_SSL(K) and the distance D_uvSSL from the black-body radiation locus is changed.

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

a maximum distance L between two arbitrary points on a virtual outer periphery enveloping the entire light emitting areas closest to each other, is 0.4 mm or more and 200 mm or less.

14. 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).

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

a correlated color temperature T_SSL (K) of light emitted from the light-emitting device in the radiant direction satisfies

2550(K)≦

T_SSL(K)≦

7000(K).

16. 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.

17. 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.

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

19. The light-emitting device according to claim 18, wherein

the phosphor includes one to five types of phosphors each having different emission spectra.

20. The light-emitting device according to claim 18, wherein the phosphor includes a green phosphor and a red phosphor.

21. The light-emitting device according to claim 20, wherein the green phosphor has 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 nm to 130 nm.

22. The light-emitting device according to claim 20, wherein the red phosphor has 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.

23. The light-emitting device according to claim 20, wherein the green phosphor is a narrow band green phosphor.

24. The light-emitting device according to claim 20, wherein the green phosphor is β

-SiAlON.

25. The light-emitting device according to claim 20, wherein the red phosphor is SCASN.

26. An illumination method comprising:

illuminated objects preparation step of preparing illuminated objects; and

an illumination step of illuminating the objects by light emitted from a light-emitting devices which includes M number of light emitting areas (M is 2 or greater natural number) and has light-emitting elements in the light-emitting areas,

in the illumination step, when light emitted from the light-emitting devices illuminate the objects, the objects are illuminated so that the light measured at a position of the objects satisfies <

1′

> and

<

2′

>

below;

<

1′

>

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

0.0350≦

D_uvSSL<

0; and

<

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 light measured at the position of the objects are respectively denoted by a*_nSSL and b*_nSSL (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_SSL (K) of the light measured at the position of the objects 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), and

an average saturation difference represented by formula (3) below satisfies formula (4) below and

27. The illumination method according to claim 26, wherein

in the illumination step, when light emitted from the light-emitting devices illuminate the objects, the objects are illuminated so that the light measured at a position of the objects further satisfies <

2″

>

below;

<

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.

28. The illumination method according to claim 26, wherein

in the illumination step, when light emitted from the light-emitting devices illuminate the objects, the objects are illuminated so that the light measured at a position of the objects further satisfies <

3>

below;

<

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 light measured at the position of the objects are denoted by θ

_nSSL (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_SSL (K) of the light measured at the position of the objects 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),

here Δ

h_n=θ

_nSSL−

θ

_nref.

29. The illumination method according to claim 26, wherein

a semiconductor light-emitting element is included in at least one of the light emitting areas as the light-emitting element.

30. The illumination method according to claim 26, wherein

when φ

_SSLN(λ

) (N is 1 to M) is a spectral power distribution of a light which has been emitted from each light-emitting element and has reached the position of the objects, and φ

_SSL(λ

) is a spectral power distribution of the light measured at the position of the objects is represented by

31. The illumination method according to claim 26, wherein

at least one light emitting area of the M number of light emitting areas is electrically driven independently from other light emitting areas for performing the illumination.

32. The illumination method according to claim 31, wherein

all the M number of light emitting areas are electrically driven independently from other light emitting areas.

33. The illumination method according to claim 26, wherein

at least one selected from the group consisting of an average saturation difference represented by the formula (3),

34. The illumination method according to claim 33, wherein

the luminance in the object is independently controlled when at least one selected from the group of an average saturation difference represented by the formula (3),

35. The illumination method according to claim 34, wherein

the luminance in the object is unchangeable when at least one selected from the group of an average saturation difference represented by the formula (3),

36. The illumination method according to claim 34 wherein

the luminance in the object is decreased when the average saturation difference represented by the formula (3),

37. The illumination method according to claim 34, wherein

the illuminance in the object is increased when the correlated color template T_SSL(K) is increased.

38. The illumination method according to claim 34, wherein

the luminance in the object is decreased when the distance D_uvSSL from the black-body radiation locus is decreased.

39. The illumination method according to claim 26, wherein

if a maximum distance between two arbitrary points on a virtual outer periphery enveloping the entire light emitting areas closest to each other is denoted by L, and a distance between the light-emitting device and the illumination object is denoted by H,

the distance H is set so as to satisfy

5×

L≦

H≦

500×

L.