LIGHT EMITTING DEVICE, AND ILLUMINATION LIGHT SOURCE, DISPLAY UNIT AND ELECTRONIC APPARATUS INCLUDING THE LIGHT EMITTING DEVICE

• US 20110211336A1
• Filed: 02/23/2011
• Published: 09/01/2011
• Est. Priority Date: 02/26/2010
• Status: Abandoned Application

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: OSHIO, Shozo
• Application Number:
  US13/033,225
• Publication Number:
  US 20110211336A1
• Time in Patent Office: Days
• US Class Current: 362/97.1
• CPC Class Codes: F21K 9/00 Light sources using semiconductor devices as light-generating elements, e.g. using light-emitting diodes [LED] or lasers
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/133609 including means for improving the color mixing, e.g. white
• CPC Class Codes: G02F 1/133611 including means for improving the brightness uniformity
• CPC Class Codes: G02F 1/133614 using photoluminescence, e.g. phosphors illuminated by UV or blue light
• CPC Class Codes: G02F 1/133624 characterised by their spectral emissions
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• 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 33/50 Wavelength conversion elements
• CPC Class Codes: H01L 33/54 having a particular shape

Abstract

A light emitting device includes: a first semiconductor light emitting element having a solid-state blue light emitting element that emits blue light with a light emission peak in a wavelength range from 420 nm to less than 480 nm, and a first red phosphor layer that covers the solid-state blue light emitting element and includes a first red phosphor that emits red light with a light emission peak in a wavelength range from 600 nm to less than 680 nm; and a second semiconductor light emitting element having a solid-state green light emitting element that emits green light with a light emission peak in a wavelength range from 500 nm to less than 550 nm, and a second red phosphor layer that covers the solid-state green light emitting element and includes a second red phosphor that emits red light with a light emission peak in a wavelength range from 600 nm to less than 680 nm.

Claims

1. A light emitting device comprising:

a first semiconductor light emitting element having a solid-state blue light emitting element that emits blue light with a light emission peak in a wavelength range from 420 nm to less than 480 nm, and a first red phosphor layer that covers the solid-state blue light emitting element and includes a first red phosphor that emits red light with a light emission peak in a wavelength range from 600 nm to less than 680 nm; and

a second semiconductor light emitting element having a solid-state green light emitting element that emits green light with a light emission peak in a wavelength range from 500 nm to less than 550 nm, and a second red phosphor layer that covers the solid-state green light emitting element and includes a second red phosphor that emits red light with a light emission peak in a wavelength range from 600 nm to less than 680 nm.

2. The light emitting device according to claim 1, wherein the first semiconductor light emitting element emits blue/red mixed color light obtained by allowing the first red phosphor to convert a wavelength of at least a part of the blue light emitted from the solid-state blue light emitting element, and the second semiconductor light emitting element emits green/red mixed color light obtained by allowing the second red phosphor to convert a wavelength of at least a part of the green light emitted from the solid-state green light emitting element.

3. The light emitting device according to claim 2, wherein the blue/red mixed color light and the green/red mixed color light are mixed with each other further.

4. The light emitting device according to claim 1, wherein the first red phosphor layer is disposed so as to cover at least a main light extraction surface of the solid-state blue light emitting element, and the second red phosphor layer is disposed so as to cover at least a main light extraction surface of the solid-state green light emitting element.

5. The light emitting device according to claim 1, wherein the first semiconductor light emitting element and the second semiconductor light emitting element are disposed so as to be spaced apart from each other.

6. The light emitting device according to claim 1, wherein the first and second red phosphors each are at least one selected from the group consisting of an alkaline earth metal nitride phosphor activated with Eu²⁺ and an alkaline earth metal oxynitride phosphor activated with Eu²⁺.

7. The light emitting device according to claim 1, wherein none of a solid-state light emitting element and a phosphor substance that emit light with a light emission peak in a wavelength range from 480 nm to less than 500 nm, and a solid light emitting element and a phosphor substance that emit light with a light emission peak in a wavelength range from 550 nm to less than 600 nm is present.

8. The light emitting device according to claim 1, wherein the solid-state blue light emitting element and the solid-state green light emitting element each are an injection type electroluminescent element in which a light emitting layer is composed of an inorganic material.

9. The light emitting device according to claim 8, wherein the inorganic material is an InGaN semiconductor compound.

10. The light emitting device according to claim 1, wherein thicknesses of the phosphor layers and/or concentrations of the red phosphors included in the phosphor layers are different between the first semiconductor light emitting element and the second semiconductor light emitting element.

11. The light emitting device according to claim 1, wherein the first semiconductor light emitting element further has a light diffuser between the solid-state blue light emitting element and the first red phosphor layer, and the second semiconductor light emitting element further has a light diffuser between the solid-state green light emitting element and the second red phosphor layer.

12. An illumination light source comprising the light emitting device according to claim 1.

13. The illumination light source according to claim 12 in the form of a backlight.

14. The illumination light source according to claim 13, wherein a plurality of the light emitting devices are disposed dispersedly so as to configure the backlight.

15. A display unit comprising the backlight according to claim 13.

16. An electronic apparatus comprising the display unit according to claim 15.