LED illumination device for reducing occurrence of color heterogeneity

• US 8,455,887 B2
• Filed: 03/25/2010
• Issued: 06/04/2013
• Est. Priority Date: 03/26/2009
• Status: Expired due to Fees

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Shirakawa, Tomoki, Matsubayashi, Yoko
• Primary Examiner(s): Pert, Evan
• Assistant Examiner(s): MUNOZ, ANDRES F
• Application Number:
  US12/659,915
• Publication Number:
  US 20100244061A1
• Time in Patent Office: 1,167 Days
• Field of Search: None
• US Class Current: 257/88
• 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: F21Y 2105/10 comprising a two-dimensional array of point-like light-generating elements
• CPC Class Codes: F21Y 2105/12 characterised by the geometrical disposition of the light-generating elements, e.g. arranging light-generating elements in differing patterns or densities
• 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 25/0753 the devices being arranged next to each other
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 33/54 having a particular shape

Abstract

An LED illumination device includes: a substrate; one or more red LED chips arranged on the substrate; a plurality of blue LED chips arranged on the substrate; and a plurality of third-color LED chips arranged on the substrate. Respective centers of the red LED chips are arranged on a circumference of a first circle having as its center a point on the substrate, respective centers of the blue LED chips being arranged on the circumference of a second circle concentric with and greater than the first circle, respective centers of the third-color LED chips being arranged in a region between the first circle and the second circle.

Claims

1. A light emitting diode (LED) illumination device comprising:

a substrate;

a plurality of red LED chips arranged on the substrate;

a plurality of blue LED chips arranged on the substrate; and

a plurality of third-color LED chips arranged on the substrate,

wherein respective centers of the plurality of red LED chips are arranged on a circumference of a first circle having as its center a point on the substrate, respective centers of the plurality of blue LED chips are arranged on a circumference of a second circle concentric with and greater than the first circle, and respective centers of the plurality of third-color LED chips are arranged in a region between the first circle and the second circle,

wherein the LED illumination device further comprises a bell-shaped sealing portion covering all of the plurality of red, the plurality of blue and the plurality of third-color LED chips, the bell-shaped sealing portion containing a light diffusion agent, and

wherein the total concentration of the light diffusion agent contained within the bell-shaped sealing portion is greater in the entire region directly above the plurality of blue LED chips than in the entire region directly above the plurality of red LED chips so that the light distribution of the plurality of blue LED chips is broader than that of the plurality of red LED chips.

2. The LED illumination device of claim 1, wherein each of the plurality of blue LED chips has a square shape and a distance between the center of each of the plurality of red LED chips and that of a blue LED chip closest thereto is not less than twice a length of one side of the blue LED chip.