Light source having blue, blue-green, orange and red LED's

• US 7,008,078 B2
• Filed: 06/02/2004
• Issued: 03/07/2006
• 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: Nagai, Hideo, Tamura, Tetsushi, Shimizu, Masanori, Matsui, Nobuyuki, Shimomura, Yoko
• Primary Examiner(s): Sember, Thomas M.
• Assistant Examiner(s): Negron, Ismael
• Application Number:
  US10/859,481
• Publication Number:
  US 20050002191A1
• Time in Patent Office: 643 Days
• Field of Search: 362/327, 362/231, 362/800, 362/555, 362/545, 362/84, 362/2, 362/293, 362/11, 362/27, 362/601, 362/227, 362/230, 362235-238, 362/249, 313/512, 267/85, 257/89, 257/102, 257/79, 257/88, 257/90, 257/100
• 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.

Claims

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

wherein the four types of light-emitting diodes are a first diode having an emission wavelength peak at 450 to 470 nm, a second diode having an emission wavelength peak at 510 to 540 nm, a third diode having an emission wavelength peak at 580 to 600 nm and a fourth diode having an emission wavelength peak at 625 to 650 nm.

2. 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 first diode, the second diode, the third diode and the fourth diode increase in this order.

3. 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 first diode, the second diode, the third diode and the fourth diode increase in this order.

4. 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.

5. The illumination light source according to claim 1,

wherein an emitting site of the first diode and an emitting site of the third diode are provided within a single chip, and

an emitting site of the fourth diode and an emitting site of the second diode are provided within a single chip.

6. The illumination light source according to claim 1,

wherein the first diode emits blue light,

the second diode emits blue-green light,

the third diode emits orange light, and

the fourth diode emits red light.

7. 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 first diode is higher than the luminous intensity of the second diode, and the luminous intensity of the fourth diode is higher than the luminous intensity of the third diode.

8. The illumination light according to claim 7, wherein 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 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 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.

10. 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 first diode is higher than the luminous intensity of the second diode, and the luminous intensity of the fourth diode is higher than the luminous intensity of the third diode.

11. The illumination source according to claim 10, 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.

12. The illumination light source according to claim 11, 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.

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

14. The illumination light source according to claim 13,

wherein the phosphor is a yellow or a green emitting phosphor that is excited by an emission of the first 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.