Load control device having an electrically isolated antenna

• US 9,155,172 B2
• Filed: 05/10/2012
• Issued: 10/06/2015
• Est. Priority Date: 05/13/2011
• Status: Active Grant

• Current Assignee: Lutron Technology Company LLC
• Original Assignee: Lutron Electronics Company Incorporated (Lutron Electronics)
• Inventors: Baragona, Robert, Blakeley, Matthew Robert, Bollinger, Robert Jr., Tuncay, Orbay
• Primary Examiner(s): Fureman, Jared
• Assistant Examiner(s): YESHAW, ESAYAS G
• Application Number:
  US13/468,914
• Publication Number:
  US 20120313456A1
• Time in Patent Office: 1,244 Days
• Field of Search: 307/326
• US Class Current: 1/1
• CPC Class Codes: H01Q 1/002 Protection against seismic waves, thermal radiation or other disturbances, e.g. nuclear explosion; Arrangements for improving the power handling capability of an antenna
• CPC Class Codes: H01Q 1/007 specially adapted for indoor communication
• CPC Class Codes: H01Q 1/2216 used in interrogator/reader equipment
• CPC Class Codes: H05B 47/19 via wireless transmission
• CPC Class Codes: H05K 1/0239 Signal transmission by AC coupling
• CPC Class Codes: H05K 1/162 incorporating printed capacitors

Abstract

A load control device for controlling the power delivered from a power source to an electrical load includes an antenna and a communication circuit to receive and transmit messages via radio frequency (RF) signals. The communication circuit is coupled to the power source but is capacitively coupled to the antenna. The capacitive coupling is formed through multiple layers of a printed circuit board (PCB) in which each layer includes a conductive trace that neighbors another conductive trace on an adjacent layer. The capacitive coupling provides that the antenna is electrically isolated from the communication circuit which accordingly, provides that the antenna is electrically isolated from the power source.

Claims

1. A load control device operable to control the amount of power delivered to a load from an AC power source, the load control device comprising:

a printed circuit board comprising a first layer comprising a first trace and a second layer comprising a second trace, the first and second traces being positioned parallel to one another;

an enclosure containing the printed circuit board;

a communication circuit electrically coupled to the first trace; and

a wire monopole antenna electrically coupled to the second trace, the wire monopole antenna being adjustable into one or more positions, a first position of the one or more positions including the wire monopole antenna extending freely from the enclosure, the first position increasing a range of reception of the wire monopole antenna relative to the wire monopole antenna not extending freely from the enclosure;

wherein the first trace is oriented to form a capacitive coupling with respect to the second trace, such that the antenna is capacitively coupled to the communication circuit.

2. The load control device of claim 1, wherein the capacitive coupling provides electrical isolation between the antenna and the AC power source.

3. The load control device of claim 2, further comprising:

a power supply operable to provide a DC supply voltage for powering the communication circuit, the DC supply voltage derived from the AC power source;

wherein the capacitive coupling provides electrical isolation between the antenna and the power supply.

4. The load control device of claim 3, wherein the communication circuit comprises at least a radio frequency receiver.

5. The load control device of claim 2, further comprising:

a controllably conductive device operable to control the amount of AC power delivered to the load;

wherein the antenna is electrically isolated from the controllably conductive device.

6. The load control device of claim 2, wherein the capacitive coupling has a capacitance of between approximately 10 picofarads and 100 picofarads.

7. The load control device of claim 2, wherein the printed circuit board further comprises a non-conductive layer positioned between the traces of the first and second layers of the printed circuit board.

8. The load control device of claim 7, wherein the printed circuit board comprises:

a third layer comprising a third trace electrically coupled to the first trace; and

a fourth layer comprising a fourth trace electrically coupled to the second trace;

wherein the first, second, third, and fourth traces are positioned parallel to one another and the second trace is positioned between the first and third traces, and the third trace is positioned between the second and fourth trace such that the first and third traces are capacitively coupled to the second and fourth traces.

9. The load control device of claim 8, wherein the first, second, third and fourth traces of the printed circuit board each comprise an area of approximately 0.0625 square inches.

10. The load control device of claim 8, wherein the thickness of the first, second, third and fourth traces is between approximately 0.0007 and 0.0014 inches.

11. The load control device of claim 10, wherein the distance between each of the first, second, third, and fourth traces is between approximately 0.0225 and 0.014 inches.

12. The load control device of claim 7, wherein the printed circuit board is a 2-layer printed circuit board wherein the first layer and the second layer form the outer layers of the printed circuit board.

13. The load control device of claim 7, wherein the printed circuit board is a 4-layer printed circuit board.

14. The load control device of claim 1, wherein the enclosure further comprises a mechanical channel adapted to receive the antenna in a second position of the one or more positions.

15. The load control device of claim 14, wherein the antenna is removable from the mechanical channel of the enclosure such that the antenna extends freely from the enclosure in the first position.

16. A message receiving structure for use in a load control device, the load control device having an enclosure containing the printed circuit board, the message receiving structure comprising:

a printed circuit board having a first layer comprising a first trace, a second layer comprising a second trace, a third layer comprising a third trace, and a fourth layer comprising a fourth trace, the traces being positioned parallel to one another and the second trace being positioned between the first and third traces, and the third trace being positioned between the second and fourth traces;

a communication circuit electrically coupled to the first and third traces; and

a wire monopole antenna electrically coupled to the second and fourth traces;

wherein the first and third traces are oriented to form a capacitive coupling with respect to the second and fourth traces, such that the antenna is capacitively coupled to the communication circuit;

wherein the wire monopole antenna is adjustable into one or more positions, a first position of the one or more positions includes the wire monopole antenna extending freely from the enclosure, and the first position increases a range of reception of the wire monopole antenna relative to the wire monopole antenna not extending freely from the enclosure.

17. The message receiving structure of claim 16, wherein the load control device is adapted to be coupled to an AC power source, and the capacitive coupling provides electrical isolation between the antenna and the AC power source.

18. The message receiving structure of claim 16, wherein the capacitive coupling has a capacitance of between approximately 10 picofarads and 100 picofarads.