Multichip on-board LED illumination device

• US 7,479,660 B2
• Filed: 11/03/2005
• Issued: 01/20/2009
• Est. Priority Date: 10/21/2005
• Status: Active Grant

• Current Assignee: Qioptiq Photonics GmbH & Company KG (Excelitas Technologies Holdings LLC)
• Original Assignee: Excelitas Technologies Elcos GmbH (Revvity, Inc.)
• Inventors: Kobilke, Siegmund
• Primary Examiner(s): PERT, EVAN T
• Application Number:
  US11/265,914
• Publication Number:
  US 20070090375A1
• Time in Patent Office: 1,174 Days
• Field of Search: 257/89, 257/99, 257/100, 362/231, 362/252
• US Class Current: 257/89
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48472 the other connecting portion not on the bonding area also being a wedge bond, i.e. wedge-to-wedge
• 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 33/483 Containers
• CPC Class Codes: H01L 33/54 having a particular shape
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/40 Details of LED load circuits

Abstract

An LED-based illumination device can use an array of four LEDs to produce high intensity light over a broad color spectrum and a broad range of color temperature. A high quality white light can be produced by using two green LEDs with a single red and a single blue LED.

Claims

1. An illumination device, comprising:

a single red light emitting diode (LED);

a single blue LED;

only one pair of green LEDs connected in series; and

a substrate supporting the red, blue, and pair of green LEDs in a compact arrangement, the substrate including a circuit layout operable to receive current from an external source and pass that current to an appropriate one of the red, blue, and pair of green LEDs for generating light.

2. An illumination system according to claim 1, wherein:

the red, blue, and pair of green LEDs are packed in a square array.

3. An illumination system according to claim 2, wherein:

the pair of green LEDs are positioned diagonally opposite each other in the square array.

4. An illumination device, comprising:

a substrate having an isolation layer formed thereon;

a circuit layout positioned on the isolation layer, the circuit layout including a central bonding pad and a plurality of anode and cathode pads;

a square array of four LED chips secured on the bonding pad, the square array including one red LED, one blue LED, and a pair of green LEDs, each of the red, blue, and pair of green LEDs electrically connected to the circuit layout in order to allow activation through the application of current to an appropriate pair of the plurality of anode and cathode pads; and

an encapsulant positioned over the square array of four LED chips to prevent external contact with the square array while out coupling light from the square array.

5. An illumination device according to claim 4, wherein:

the red LED is electrically connected to the bonding pad.

6. An illumination device according to claim 4, wherein:

the blue and pair of green LEDs are electrically isolated from the bonding pad.

7. An illumination device according to claim 4, further comprising:

a retaining ring positioned on the isolation layer and operable to retain the encapsulant positioned over the square array.

8. An illumination device according to claim 4, wherein:

there is only one anode pad and one cathode pad for the pair of green LEDs.

9. An illumination device according to claim 4, wherein:

the substrate is a metal substrate.

10. An illumination device according to claim 4, wherein:

the pair of green LEDs are connected in series.

11. A system for generating light of various colors, comprising:

an illuminator including four LED chips including one red chip, one single blue chip, and only two green chips laid out in a closely spaced array on a substrate;

electrical circuitry for selectively driving the chips with current to produce light; and

a controller for controlling the electrical circuitry to vary current used to drive the chips to produce a selected color output.

12. A system according to claim 11, wherein:

said green chips are connected in series and said electrical circuitry provides selectable drive currents to the red chip, the blue chip, and the series-connected green chips.

13. An illumination device, comprising:

a substrate having an isolation layer formed thereon;

a circuit layout positioned on the isolation layer, the circuit layout including a central bonding pad and a plurality of anode and cathode pads;

a square array of four closely packed LED chips secured on the bonding pad, each of the LEDs being electrically connected to the circuit layout in order to allow activation through the application of current to an appropriate pair of the plurality of anode and cathode pads; and

an encapsulant positioned over the square array of four ED chips to prevent external contact with the square array while out coupling light from the square array.

14. An illumination device as recited in claim 13, wherein the four LED'"'"'s are packed within an area less than 9 mm².