Semiconductor light source using a primary and secondary heat sink combination

• US 6,634,771 B2
• Filed: 08/24/2001
• Issued: 10/21/2003
• Est. Priority Date: 08/24/2001
• Status: Active Grant

• Current Assignee: Epistar Corporation
• Original Assignee: CAO Group, Inc.
• Inventors: Cao, Densen
• Primary Examiner(s): O'Shea, Sandra
• Assistant Examiner(s): Choi, Jacob Y.
• Application Number:
  US09/939,488
• Publication Number:
  US 20030039120A1
• Time in Patent Office: 788 Days
• Field of Search: 362/800, 362/545, 362/294, 362/373, 362/547, 362/230
• US Class Current: 362/294
• CPC Class Codes: F21K 9/232 specially adapted for generating an essentially omnidirectional light distribution, e.g. with a glass bulb
• CPC Class Codes: F21K 9/64 using wavelength conversion means distinct or spaced from the light-generating element, e.g. a remote phosphor layer
• CPC Class Codes: F21V 3/04 characterised by materials, surface treatments or coatings
• CPC Class Codes: F21Y 2107/40 on the sides of polyhedrons, e.g. cubes or pyramids
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: F21Y 2115/30 Semiconductor lasers
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48137 the bodies being arranged next to each other, e.g. on a common substrate
• CPC Class Codes: H01L 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2224/8592 Applying permanent coating, e.g. protective coating
• 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 2924/00014 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: Y10S 362/80 Light emitting diode

Abstract

A semiconductor light source for illuminating a physical space has been invented. In various embodiments of the invention, a semiconductor such as and LED chip, laser chip, LED chip array, laser array, an array of chips, or a VCSEL chip is mounted on a heat sink. The heat sink may have multiple panels for mounting chips in various orientations. The chips may be mounted directly to a primary heat sink which is in turn mounted to a multi-panel secondary heat sink. A TE cooler and air circulation may be provided to enhance heat dissipation. An AC/DC converter may be included in the light source fitting.

Claims

1. A semiconductor light source comprising:

an enclosure, said enclosure being fabricated from a transparent material through which visible light may pass, said enclosure being generally impermeable to gas,

a base to which said enclosure is mounted, said base including a fitting of appropriate shape for insertion into a light bulb socket,

an interior volume within said enclosure,

a secondary heat sink located in said interior volume, said heat sink being capable of drawing heat from a Light emitting semiconductor device mounted on said heat sink,

a plurality of primary heat sinks affixed to said secondary heat sink so that said secondary heat sink serves to draw heat away from said primary heat sink,

a plurality of light emitting semiconductor devices affixed to said primary heat sinks in a 1;

1 correspondence, at least some of said light emitting semiconductor devices being capable of emitting light having a wavelength in the range of about 200 nanometers to about 700 nanometers.

a thermoelectric cooler located on said heat sink, said thermoelectric cooler experiencing a decrease in temperature when exposed to a voltage,

an air entrance, an air exit, and an interior airflow path through said secondary heat sink, said airflow path permitting air to enter said heat sink through said air entrance, absorb heat from said secondary heat sink, and exit said heat sink through said air exit,

air located within said enclosure,

a fan within said enclosure for bringing air into said air entrance and forcing air through said airflow path and through said air exit,

an electrical connection between at least two of said light emitting semiconductor devices,

an AC/DC converter, and

an electrical connection between said AC/DC converter and said light emitting semiconductor devices.

2. A device as recited in claim 1 wherein at least one of said light emitting semiconductor devices includes a substrate on which epitaxial layers are grown.

3. A device as recited in claim 2 further comprising a buffer layer located on said substrate, said buffer layer serving to mitigate differences in material properties between said substrate arid other epitaxial layers.

4. A device as recited in claim 2 further comprising:

a first cladding layer serving to confine electron movement within the chip, said first cladding layer being adjacent said buffer layer,

an active layer, said active layer emitting light when electrons jump to a valance state,

a second cladding layer, said second cladding layer positioned so that said active layer lies between cladding layers,

a first and a second reflective layer, each of said first and second reflective layers being located on opposite sides of said active layer, said reflective layers serving to reflect light emitted by said active layer, and

a contact layer on which an electron may be mounted for powering said semiconductor.

5. A device as recited in claim 2 wherein said substrate is selected from the group consisting of Si, GaAs, GaN, InP, sapphire, SIC, GaSb, InAs.

6. A device as recited in claim 2 wherein at least one of said epitaxial layers includes a material selected from the group consisting of GaN, AlGaN, AlN, AlGaN, GaInN, and GaInN.

7. A device as recited in claim 1 further comprising:

a luminous powder coating on the interior of said enclosure.

8. A semiconductor light bulb comprising:

an enclosure, said enclosure being fabricated from a transparent material through which visible light may pass, said enclosure being generally impermeable to gas,

a base to which said enclosure is mounted, said base including a fitting of appropriate shape for insertion into a light bulb socket,

an interior volume within said enclosure,

a secondary heat sink located in said interior volume, said heat sink being capable of drawing heat from a light emitting semiconductor device mounted on said heat sink,

a plurality of primary heat sinks affixed to said secondary heat sink so that said secondary heat sink serves to draw heat away from said primary heat sink,

a plurality of light emitting semiconductor devices affixed to said primary heat sinks in a 1;

1 correspondence, at least some of said light emitting semiconductor devices being capable of emitting light having a wavelength in the range of about 200 nanometers to about 700 nanometers,

a thermoelectric cooler located on said secondary heat sink, said thermoelectric cooler experiencing a decrease in temperature when exposed to a voltage,

an air entrance, an air exit, and an interior airflow path through said secondary heat sink,

said air entrance and air exit being proximate a fitting for electrical connection to a light bulb socket,

said airflow path proceeding from said air entrance toward the top of the bulb, turning 90 degrees to move laterally a predetermined distance, then turning 90 degrees to move down tow&

d the bottom of the bulb, and out said air exit,

said airflow path permitting air to enter said secondary heat sink through said air entrance, absorb heat from said heat sink, and exit said heat sink through said air exit,

air located within said enclosure,

a fan within said enclosure for bringing air into said air entrance and forcing air through said airflow path arid through said air exit,

an electrical connection between at least two of said light emitting semiconductor devices,

an AC/DC converter,

a fitting for electrical connection to a light bulb socket,

electrical connection between said AC/DC converter and said light emitting semiconductor devices, and

electrical connection between said fitting and said AC/DC converter.