Light-emitting diode device

• US 6,521,915 B2
• Filed: 03/14/2001
• Issued: 02/18/2003
• Est. Priority Date: 03/14/2000
• Status: Active Grant

• Current Assignee: Asahi Rubber Inc.
• Original Assignee: Asahi Rubber Inc.
• Inventors: Hashimoto, Kazuaki, Takagi, Kazuhisa, Odaki, Tsutomu, Ichikawa, Akira, Tasaki, Masutsugu
• Primary Examiner(s): JACKSON JR, JEROME
• Application Number:
  US09/805,461
• Publication Number:
  US 20010050371A1
• Time in Patent Office: 706 Days
• Field of Search: 257/89, 257/90, 257/98, 257/100
• US Class Current: 257/98
• CPC Class Codes: C09K 11/7731 with alkaline earth metals
• CPC Class Codes: C09K 11/7774 Aluminates
• CPC Class Codes: C09K 11/7794 Vanadates; Chromates; Molybdates; Tungstates
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• 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 33/502 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

Abstract

An LED device is provided that has an excellent color rendering property and no toxicity and does not increase production costs more than necessary. A covering member is also provided used for such a device. The LED device comprises a light-emitting element for emitting light in a blue to green region and a fluorescent substance containing a red phosphor for converting the wavelength of the light emitted from the light-emitting element to another wavelength. The red phosphor is CaS activated by Eu or a phosphor expressed by the general formula AEu_(1−x)Ln_xB₂O₈, wherein A is an element selected from the group consisting of Li, K, Na and Ag; Ln is an element selected from the group consisting of Y, La and Gd; and B is W or Mo; and x is number equal to or larger than 0, but smaller than 1.

Claims

1. A light-emitting diode device, comprising

a light-emitting element for emitting light of blue to green region and

a fluorescent substance containing a phosphor expressed by a general formula AEu₍₁₋

x)Ln_xB₂O₈ for converting a wavelength of the light emitted from the light-emitting element, wherein A is an element selected from the group consisting of Li, K, Na and Ag;

Ln is an element selected from the group consisting of Y, La and Gd; and

B is W or Mo; and

x is number equal to or larger than 0, but smaller than 1.

2. The light-emitting diode device according to claim 1, wherein the light-emitting element emits light having a wavelength of 400 nm to 600 nm.

3. The light-emitting diode device according to claim 1, wherein the fluorescent substance further contains a Y_xGd₃₋

xAl₅O₂ (0≦

x≦

3) phosphor activated by Ce.

4. The light-emitting diode device according to claim 3, wherein the light-emitting diode device has an average color rendering evaluation number (Ra) of 85 or larger.

5. The light-emitting diode device according to claim 3, wherein the light-emitting diode device has a special color rendering evaluation number R₉ of 80 or larger.

6. The light-emitting diode device according to claim 2, wherein a ratio (I_a:

I_b) of emission intensity (I_a) of light having 470 nm±

2 mn to emission intensity (I_b) of light having 610 to 640 nm is 1;

0.5 to 1;

2.

7. The light-emitting diode device according to claim 1, wherein the fluorescent substance is in the form of a layer placed on an outer surface of the light-emitting element.

8. The light-emitting diode device according to claim 1, wherein the fluorescent substance is made of a transparent resin containing the AEu₍₁₋

x)Ln_xB₂O₈ phosphor and seals the light-emitting element.

9. The light-emitting diode device according to claim 1, wherein the light-emitting element is sealed with a transparent resin to form a sealed member, the sealed member is covered with a covering member including the fluorescent substance.

10. The light-emitting diode device according to claim 9, wherein the covering member is made from a polymer composition containing 100 parts by mass of a base polymer, 2 to 40 parts by mass of a phosphor expressed by AEu₍₁₋

x)Ln_xB₂O₈, and a Y_xGd<sub>3−

x</sub>Al₅O₁₂ phosphor activated by Ce.

11. The light-emitting diode device according to claim 10, wherein the base polymer comprises a rubber and/or a thermoplastic elastomer.

12. The light-emitting diode device according to claim 9, wherein the covering member is made from a polymer composition containing 100 parts by mass of a base polymer, 2 to 40 parts by mass of the AEu₍₁₋

x)Ln_xB₂O₈ phosphor, and a Y_xGd<sub>3−

x</sub>Al₅O₁₂ phosphor activated by Ce.

13. The light-emitting diode device according to claim 12, wherein the base polymer comprises a rubber and/or a thermoplastic elastomer.

14. A covering member for covering a light-emitting diode device which includes a light-emitting element sealed by a transparent resin for emitting light in a blue to green region, comprising

a base polymer, and

a phosphor expressed by AEu₍₁₋

x)Ln_xB₂O₈ wherein A is an element selected from the group consisting of Li, K, Na, and Ag;

Ln is an element selected from the group consisting of Y, La and Gd; and

B is W or Mo; and

x is a number equal to or larger than 0, but smaller than 1.

15. The covering member according to claim 14, further comprising a Y_xGd₃₋

xAl₅O₁₂ phosphor activated by Ce.