LED UNIT HAVING ELECTROCHROMIC ELEMENT

• US 20120098007A1
• Filed: 07/12/2011
• Published: 04/26/2012
• Est. Priority Date: 10/22/2010
• Status: Active Grant

• Current Assignee: Advanced Optoelectronic Technology, Inc.
• Original Assignee: Advanced Optoelectronic Technology, Inc.
• Inventors: KUO, TE-WEN
• Granted Patent: US 8,648,371 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: G02F 1/157 Structural association of cells with optical devices, e.g. reflectors or illuminating devices
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• 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 33/486 adapted for surface mounting
• CPC Class Codes: H01L 33/504 Elements with two or more wavelength conversion materials
• CPC Class Codes: H01L 33/58 Optical field-shaping elements

Abstract

An LED unit includes an LED and an electrochromic element mounted on the LED. The LED includes a base, a light emitting die mounted on the base, a pair of leads electrically connected to the die and an encapsulant sealing the die. The encapsulant has a first area and a second area around the first area. The first area contains yellow phosphor therein, and the second area contains red phosphor therein. The electrochromic element has an opening through which the first area of the encapsulant is exposed. The second area of the encapsulant is covered by the electrochromic element. The electrochromic element can change its color when being electrified, thereby changing the color temperature of the light output from the LED unit.

Claims

1. An LED (light emitting diode) unit comprising:

an LED comprising;

a base;

a light emitting die mounted on the base;

a pair of leads fixed to the base and electrically connected to the light emitting die; and

an encapsulant attached to the base and covering the light emitting die; and

an electrochromic element mounted on the encapsulant of the LED to cover a part of the encapsulant, when the electrochromic element is applied with an electricity, at least one of a transmittance and a color of the electrochormic element being changed, thereby changing an optical characteristic of light output from the LED unit.

2. The LED unit of claim 1, wherein the encapsulant has a first area and a second area surrounding the first area, the light emitting die being sealed in the first area.

3. The LED unit of claim 2, wherein the first area of the encapsulant contains a first phosphor doped therein, and the second area of the encapsulant contains a second phosphor therein, the first phosphor being different from the second phosphor.

4. The LED unit of claim 3, wherein the first phosphor is excited by the light from the light emitting die to produce yellow light, and the second phosphor is excited by the light from the light emitting die to produce red light.

5. The LED unit of claim 2, wherein the electrochromic element is annular and has an opening defined through a center thereof.

6. The LED unit of claim 5, wherein the first area of the encapsulant is exposed within the opening of the electrochromic element, and the second area of the encapsulant is overlaid by the electrochromic element.

7. The LED unit of claim 1, wherein the electrochromic element is transparent and achromic when no electricity is input to the electrochromic element, and the electrochromic element turns black-blue when electricity is input to the electrochromic element.

8. The LED unit of claim 1, wherein the base defines a cavity in a top face thereof, the encapsulant being filled into the cavity.

9. The LED unit of claim 8, wherein each of the leads comprises an inner section exposed within the cavity, an outer section exposed on a bottom face of the base and a connection section interconnecting the inner section and the outer section.

10. The LED unit of claim 1, wherein a portion of the base located below the light emitting die and between the two leads has a thermal conductivity larger than that of other portions of the base.

11. An LED (light emitting diode) unit comprising:

a base;

a light emitting die mounted on the base;

a pair of leads fixed to the base and electrically connected to the light emitting die;

an encapsulant sealing the light emitting die, the encapsulant being transparent to allow light emitted from the light emitting die to transmit therethrough; and

an electrochromic element mounted on the encapsulant, the electrochromic element being switchable between a first state and a second state according to variation of electricity input thereto;

wherein when the electrochromic element is in the first state, a part of light emergent from the encapsulant transmits through the electrochromic element to an outside environment; and

wherein when the electrochromic element is in the second state, the part of light emergent from the encapsulant is at least partially blocked by the electrochromic element or has a color changed by the electrochromic element relative to that of the part of light transmitting to the outside environment through the electrochromic element in the first state.

12. The LED unit of claim 11, wherein a remaining part of the light emergent from the encapsulant directly transmits through the electrochromic element without being affected by the electrochromic element switched between the first state and the second state.

13. The LED unit of claim 12, wherein the electrochromic element is annular and defines an opening in a center thereof.

14. The LED unit of claim 13, wherein the encapsulant has a first area and a second surrounding the first area, the first area being exposed within the opening of the electrochromic element, and the second area being covered by the electrochromic element.

15. The LED unit of claim 14, wherein the first area of the encapsulant has a first phosphor doped therein, and the second area has a second phosphor doped therein, the first phosphor being different from the second phosphor.

16. The LED unit of claim 15, wherein light from the first phosphor as being excited by the light from the light emitting die has a color temperature different from that of light from the second phosphor as being excited by the light from the light emitting die.

17. The LED unit of claim 11, wherein the electrochromic element is transparent in the first state and opaque in the second state.