Illumination light source

• US 6,817,735 B2
• Filed: 05/23/2002
• Issued: 11/16/2004
• Est. Priority Date: 05/24/2001
• Status: Expired due to Term

• Current Assignee: Everlight Electronics Company Limited
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Shimomura, Yoko, Nagai, Hideo, Matsui, Nobuyuki, Tamura, Tetsushi, Shimizu, Masanori
• Primary Examiner(s): Ward, John Anthony
• Assistant Examiner(s): Zeade, Bertrand
• Application Number:
  US10/154,377
• Publication Number:
  US 20030063462A1
• Time in Patent Office: 908 Days
• Field of Search: 362/231, 362/545, 362/555, 362/800, 362/295, 313/512, 257/85
• US Class Current: 362/231
• CPC Class Codes: F21K 9/233 specially adapted for generating a spot light distribution, e.g. for substitution of reflector lamps
• CPC Class Codes: F21Y 2113/13 comprising an assembly of point-like light sources
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• CPC Class Codes: H01L 25/0756 Stacked arrangements of devices
• CPC Class Codes: H01L 25/13 the devices being of a type provided for in group H01L33/00
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01019 Potassium [K]
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 2924/3025 Electromagnetic shielding
• CPC Class Codes: Y10S 362/80 Light emitting diode

Abstract

An illumination light source includes four different types of LEDs, namely a blue light-emitting diode 11 emitting blue light, a blue-green light-emitting diode 12 emitting blue-green light, an orange light-emitting diode 13 emitting orange light and a red light-emitting diode 14 emitting red light. Thus, an illumination light source having high efficiency and high color rendering performance is provided.

Claims

1. An illumination light source comprising four types of light-emitting diodes,

wherein the four types of light-emitting diodes are a blue light-emitting diode emitting blue light having an emission wavelength peak at 420 to 470 nm, a blue-green light-emitting diode emitting blue-green light having an emission wavelength peak at 500 to 550 nm, an orange light-emitting diode emitting orange light having an emission wavelength peak at 570 to 600 nm and a red light-emitting diode emitting red light having an emission wavelength peak at 610 to 660 nm;

and

the light source having a general color rendering index of at least 90.

2. The illumination light source according to claim 1,

wherein the blue light-emitting diode has an emission wavelength peak at 450 to 470 nm;

the blue-green light-emitting diode has an emission wavelength peak at 510 to 540 nm;

the orange light-emitting diode has an emission wavelength peak at 580 to 600 nm; and

the red light-emitting diode has an emission wavelength peak at 625 to 650 nm.

3. The illumination light source according to claim 1, wherein the emission wavelength peaks of the four types of light-emitting diodes are different from corresponding hypothetical emission wavelength peaks that are calculated based on results of a theoretical simulation.

4. The illumination light source according to claim 1, wherein, when the illumination light source has a correlated color temperature of less than 5000 K and when a color rendering performance of the illumination light source is evaluated using a blackbody source as a standard source, the illumination light source has a spectral distribution in which the luminous intensities of the blue light-emitting diode, the blue-green light-emitting diode, the orange light-emitting diode and the red light-emitting diode increase in this order.

5. The illumination light source according to claim 2, wherein, when the illumination light source has a correlated color temperature of less than 5000 K and when a color rendering performance of the illumination light source is evaluated using a blackbody source as a standard source, the illumination light source has a spectral distribution in which the luminous intensities of the blue light-emitting diode, the blue-green light-emitting diode, the orange light-emitting diode and the red light-emitting diode increase in this order.

6. The illumination light source according to claim 1, wherein, when the illumination light source has a correlated color temperature of at least 5000 K and when the color rendering performance of the illumination light source is evaluated using an artificial daylight source as the standard source, the illumination light source has a spectral distribution, in which the luminous intensity of the blue light-emitting diode is higher than the luminous intensity of the blue-green light-emitting diode, and the luminous intensity of the red light-emitting diode is higher than the luminous intensity of the orange light-emitting diode.

7. The illumination light source according to claim 2, wherein, when the illumination light source has a correlated color temperature of at least 5000 K and when the color rendering performance of the illumination light source is evaluated using an artificial daylight source as the standard source, the illumination light source has a spectral distribution, in which the luminous intensity of the blue light-emitting diode is higher that the luminous intensity of the blue-green light-emitting diode, and the luminous intensity of the red light-emitting diode is higher than the luminous intensity of the orange light-emitting diode.

8. The illumination light source according to claim 6, wherein a gamut area obtained by connecting four chromaticity coordinates of special color rendering indices R9 through R12 of respective test colors rendered by the illumination light source is larger than the gamut area obtained by connecting the four chromaticity coordinates of the respective test colors rendered by the standard source.

9. The illumination source according to claim 7, wherein a gamut area obtained by connecting four chromaticity coordinates of special color rendering indices R9 through R12 of respective test colors rendered by the illumination light source is larger than the gamut area obtained by connecting the four chromaticity coordinates of the respective test colors rendered by the standard source.

10. The illumination light source according to claim 8, wherein a ratio (Ga4) of a gamut area obtained by connecting four chromaticity coordinates of special coloring rendering indices R9 through R12 of the respective test colors rendered by the illumination light source to a gamut area obtained by connecting the four chromaticity coordinates of the respective test colors rendered by the standard source is larger than a ratio (Ga) of a gamut area obtained by connecting eight chromaticity coordinates of color rendering indices R1 through R8 of respective test colors rendered by the illumination light source to a gamut area obtained by connecting the eight chromaticity coordinates of the respective test colors rendered by the standard source.

11. The illumination light source according to claim 9, wherein a ratio (Ga4) of a gamut area obtained by connecting four chromaticity coordinates of special color rendering indices R9 through R12 of the respective test colors rendered by the illumination light source to a gamut area obtained by connecting the four chromaticity coordinates of the respective test colors rendered by the standard source is larger than a ratio (Ga) of a gamut area obtained by connecting eight chromaticity coordinates of color rendering indices R1 through R8 of respective test colors rendered by the illumination light source to a gamut area obtained by connecting the eight chromaticity coordinates of the respective test colors rendered by the standard source.

12. The illumination light source according to claim 1, further comprising a phosphor that emits light when excited by emission of the light-emitting diodes.

13. The illumination light source according to claim 12,

wherein the phosphor is a yellow or a green emitting phosphor that is excited by an emission of the blue light-emitting diode and emits light in a range between green and yellow;

and

the phosphor has an emission distribution in which a spectral half-width of the phosphor is wider than the spectral half-widths of the light-emitting diodes.

14. The illumination light source according to claim 1, further comprising a luminous intensity control means for adjusting a luminous intensity ratio of each of the four types of light emitting diodes.

15. The illumination light source according to claim 1,

wherein an emitting site of the blue light-emitting diode and an emitting site of the orange light-emitting diode are provided within a single chip, and

an emitting site of the red light-emitting diode and an emitting site of the blue-green light-emitting diode are provided within a single chip.