Abstract:
A dimmer control operable to adjust a status of a connected electrical lamp in response to a radio frequency control signal received from a remote control device, the dimmer control comprising a communication and control circuit comprising at least a radio frequency transmitter/receiver and an antenna operable to receive a radio frequency signal from the remote control device that includes control information for controlling the status of the electrical lamp; a manual actuator operable to change the on/off status of the electrical lamp; and a slider control operable to change the dimming status of the electrical lamp, wherein the slider control operates to dim the electrical lamp and the communication and control circuit is operable to transmit to the remote control device status information representing the changed status of the electrical lamp, or the setting of the slider control, or both.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This is a continuation of U.S. patent application Ser. No. 11/447,725, filed Jun. 6, 2006 and entitled LOAD CONTROL DEVICE HAVING A COMPACT ANTENNA, which application claims priority from commonly-assigned U.S. Provisional Application Ser. No. 60/687,894, filed Jun. 6, 2005, entitled REMOTE CONTROL LIGHTING CONTROL SYSTEM, the entire disclosure of which is hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to antennas and in particular, to radio frequency antennas for transmitting and receiving radio frequency (RF) signals. Even more particularly, the present invention relates to a compact antenna, which is provided for use in connection with a radio frequency controlled lighting control system. 
         [0004]    2. Description of the Related Art 
         [0005]    Systems for controlling an electrical device by remote control are known. For example, prior art systems and methods control the status of electrical devices such as electric lamps, from a remote location via communication links, including radio frequency links, power line carrier links or infrared links. Status information regarding the electrical devices (e.g., on, off and intensity level) is typically transmitted between specially adapted lighting control devices and at least one master control unit. At least one repeater device may also be provided to help ensure reliable communications between the master control unit and the control devices for the respective electrical devices. The repeater may be required when a control device is unable to receive control signals transmitted directly from the master control unit, and, typically, employs a repeater sequence for helping to ensure that each receiver receives those signals intended for it. 
         [0006]    Referring now to the drawing figures, in which like reference numerals refer to like elements, there is shown in  FIG. 1A  a prior art arrangement of a system  100  for remote control of electrical devices. The example prior art system  100  illustrated in  FIG. 1A  includes configurable devices that are manufactured by the assignee of the present patent application and commercially known as the RadioRA® lighting control system. The RadioRA® lighting control system is described in greater detail in commonly-assigned U.S. Pat. No. 5,905,442, issued May 18, 1999, entitled METHOD AND APPARATUS FOR CONTROLLING AND DETERMINING THE STATUS OF ELECTRICAL DEVICES FROM REMOTE LOCATIONS, the entire disclosure of which is hereby incorporated by reference. 
         [0007]    As shown in  FIG. 1A , the hardware devices include a master control unit  102 , two control devices  104 , a repeater  106 , a car visor control  108  that may be mounted on an automobile&#39;s sun visor, and two electrical devices  110 , e.g., lamps. The devices  102 ,  104 ,  106  and  108  transmit radio frequency signals  112 , which can include control information and instructions regarding the respective electrical devices  110 . 
         [0008]    In the prior art system  100  illustrated in  FIG. 1A , the control devices  104  are coupled to electrical devices  110  by wire connections, such as, for example, building wiring for providing power to electrical devices. Each control device  104  includes a communications and control circuit  114  that comprises a radio frequency transmitter/receiver  116  and an antenna  118  for transmitting/receiving the radio frequency signals  112 . The antenna  118  is described in greater detail in U.S. Pat. No. 5,736,965, issued Apr. 7, 1998, and U.S. Pat. No. 5,982,103, issued Nov. 9, 1999, both entitled COMPACT RADIO FREQUENCY TRANSMITTING AND RECEIVING ANTENNA AND CONTROL DEVICE EMPLOYING SAME. The entire disclosures of both patents are hereby incorporated by reference. 
         [0009]    The communications and control circuit  114  further includes a controller  120  for adjusting the status of the attached electrical device  110 . The transmitter/receiver  116  receives the radio frequency signals via the antenna  118  and transmits a status radio frequency signal with information regarding the status of the controller  120  (which indirectly reflects the status of the connected electrical device  110 ). The controller  120  adjusts the status of the electrical device in response to the control information. Each control device  104  further includes button(s)  122  and dimmer control(s)  124 , which are further operable to allow manual adjustment of the connected electrical device  110 . 
         [0010]    The master control unit  102  includes at least one actuator  126 , at least one status indicator  128 , a transmitter/receiver  116 , and an antenna  118 . The actuators  126  enable a user to control the electrical devices  110  remotely. The status indicators  128  indicate the status of the electrical devices  110 . The transmitter/receiver  116  and the antenna  118  are operable for transmitting a radio frequency signal  112  having the control information therein to control the status of the electrical devices  110 , as well as for receiving status information from the control devices  104 . 
         [0011]    The master control unit  102  can take several forms. For example, the master control unit  102  can be formed as a tabletop master, which plugs into an electrical outlet and includes a conventional antenna for transmitting and receiving signals. In another form, the master control unit  102  mounts on a wall, and is sized such that the master control unit  102  fits within the confines of a standard electrical wall box. In either form, the master control unit  102  includes a plurality of controls, each associated with a particular control device or a plurality of control devices. In the prior art, the user must program the association of the electrical control devices to a particular actuator  126  on the master control unit. Further, prior art master control units  102  must be programmed in order to provide functions allowing all control devices  104  to turn on or off substantially simultaneously. 
         [0012]    The repeater  106  may receive radio frequency signals  112  (including status information and instructions) from the master control unit  102  and, thereafter, transmit radio frequency signals  112  to the control devices  104 . Further, the repeater  106  may receive radio frequency signals  112  from the control devices  104  and, thereafter, transmit them to the master control unit  102 . 
         [0013]    The car visor control  108  provides a convenient and remotely usable interface to transmit radio frequency signals  112  to the master control unit  102 , and may be disposed in a vehicle, for example, on a vehicle&#39;s interior sun visor. The buttons  130  are provided for remotely activating the master control unit  102 . For example, the car visor control  108  can be used to cause a lighting scene to turn on/off, or may be operated to turn the electrical devices  110  on/off, via the master control unit  102 . 
         [0014]    Thus, the master control unit  102  is operable to generate radio frequency signals, which are transmitted to and received by the control devices  104 , such as light dimmers, and/or the repeater  106 . The control devices  104  use the information received in the radio frequency signals  112  to control the connected electrical devices  110  to a desired intensity. The control devices  104  preferably transmit radio frequency signals  112  via antennas  118  to the master control unit  102  (or to the master control unit  102  via the repeater  106 ) in order to indicate the status of the control devices  104  (and thus, the connected electrical devices  110 ). Using the respective devices, a combination of lighting controls in different or the same rooms of a structure, for example, can be instructed to turn on/off, thereby creating a lighting “scene” according to a user&#39;s desire. 
         [0015]      FIG. 1B  shows a front view of a prior art lighting control device  104  of the lighting control system  100  of  FIG. 1A . Lighting control devices  104  preferably fit into standard electrical wall boxes. The antenna  118 , which comprises a part of each control device  104 , is sized so as to fit within the standard electrical wall box and is preferably disposed directly behind an actuator button  150  that is provided in the opening of a designer-style faceplate  160  as shown in  FIG. 1B . An example of such an antenna is described in greater detail in co-pending commonly-assigned U.S. patent application Ser. No. 10/873,033, filed Jun. 21, 2004, entitled COMPACT RADIO FREQUENCY TRANSMITTING AND RECEIVING ANTENNA AND CONTROL DEVICE EMPLOYING SAME, the entire disclosure of which is hereby incorporated by reference. 
         [0016]    However, it is desirable to provide an RF load control device that has an actuator button that is provided in the opening of a traditional-style faceplate. It is also desirable to provide an RF load control device that will work with a metal faceplate. Therefore, there is a need for an antenna that is disposed behind the actuator button that is provided in the opening of a traditional-style faceplate. 
       SUMMARY OF THE INVENTION 
       [0017]    According to the present invention, an antenna operable to transmit or receive radio frequency signals at a specified frequency comprises a first loop and a second loop of conductive material. The first loop has an inductance, and a capacitor, the capacitor and the inductance forming a circuit resonant at the specified frequency. The second loop has two ends adapted to be electrically coupled to an electronic circuit. The second loop is substantially only magnetically coupled to the first loop and electrically insulated from the first loop. The antenna is for use with an electrical control device for controlling the power delivered to an electrical load. The first loop of conductive material is adapted to extend beyond a faceplate of the device. 
         [0018]    According to another embodiment of the present invention, an antenna for an electrical load control device for controlling the power delivered to an electrical load is operable to transmit or receive radio frequency signals at a specified frequency. The antenna comprises a printed circuit board, a first loop of conductive material, and a second loop of conductive material. The printed circuit board has first and second sides. The first loop of conductive material has an inductance, and a capacitor, the capacitor and the inductance forming a circuit resonant at the specified frequency. The first loop is formed on the first side of the printed circuit board. The second loop of conductive material has two ends adapted to be electrically coupled to an electronic circuit. The second loop is formed on a side of the printed circuit board and is substantially only magnetically coupled to the first loop. The first loop extends beyond a faceplate of the electrical control device. 
         [0019]    In addition, the present invention provides a load control device for controlling the power delivered to an electrical load. The load control device comprises a controllably conductive device, a controller, an actuator button, a faceplate, a transmitter and/or receiver, and an antenna. The controllably conductive device has a control input and is operable to control the power delivered to the electrical load. The controller is coupled to the control input of the controllably conductive device for control of the controllably conductive device. The actuator button is provided in an opening of the faceplate and is operable to provide an input to the controller. The transmitter and/or a receiver are in communication with the controller. The antenna is coupled to the transmitter and/or the receiver. The antenna is adapted to receive a first signal at a specified frequency from a remote control device and/or transmit a second signal at a specified frequency to a remote control device. The receiver is operable to couple the first signal from the antenna to the controller for remotely controlling the controllably conductive device. The receiver is operable to couple the second signal from the controller to the antenna for providing a status of the electrical load. The antenna extends through the opening of the faceplate beyond the front surface of the faceplate. 
         [0020]    Other features and advantages of the present invention will become apparent from the following description of the invention, which refers to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0021]    The invention will now be described in greater detail in the following detailed description with reference to the drawings in which: 
           [0022]      FIG. 1A  illustrates a prior art radio frequency lighting control system for remote control of electrical devices; 
           [0023]      FIG. 1B  is a front view of a prior art lighting control device of the lighting control system of  FIG. 1A ; 
           [0024]      FIG. 2  shows an exemplary hardware arrangement of components and devices of an RF lighting control system according to a preferred embodiment of the present invention; 
           [0025]      FIG. 3  shows a master control unit of the lighting control system of  FIG. 2 ; 
           [0026]      FIG. 4  is a perspective view of a load control device of the lighting control system of  FIG. 2 ; 
           [0027]      FIG. 5  is a simplified block diagram of the load control device of  FIG. 4 ; 
           [0028]      FIG. 6  shows an equivalent circuit of an antenna of the load control device of  FIG. 4 ; 
           [0029]      FIG. 7A  shows a front view of the load control device of  FIG. 4  without a faceplate; 
           [0030]      FIG. 7B  shows a right side cross-sectional view of the load control device of  FIG. 4  without a faceplate; 
           [0031]      FIGS. 8A and 8B  show the first and second sides, respectively, of a first embodiment of an antenna of the load control device of  FIG. 4 ; and 
           [0032]      FIGS. 9A and 9B  show the first and second sides, respectively, of a second embodiment of an antenna of the load control device of  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0033]    The foregoing summary, as well as the following detailed description of the preferred embodiments, is better understood when read in conjunction with the appended drawings. For the purposes of illustrating the invention, there is shown in the drawings an embodiment that is presently preferred, in which like numerals represent similar parts throughout the several views of the drawings, it being understood, however, that the invention is not limited to the specific methods and instrumentalities disclosed. 
         [0034]    Referring to  FIG. 2 , an example hardware arrangement of components and devices in a building installation in accordance with a preferred embodiment of the present invention is displayed, and referred to herein generally as remote control system  200 . As shown in  FIG. 2 , the system comprises, for example, one master control unit  202 , five control devices  204 A- 204 E, one repeater  206 , and two car visor controls  208 A,  208 B, which represent a preferred combination of devices packaged and distributed for the retail market. In accordance with the teachings herein, each of the control devices  204 A- 204 E is installed to replace a traditional mechanical switch. The control devices  204 A- 204 E are coupled to electrical devices  210 A- 210 E, respectively, for control of power delivered to the electrical devices. In the system  200  shown in  FIG. 2 , the electrical devices  210 A- 210 E are electric lamps. 
         [0035]    In a preferred embodiment of the present invention, the control devices  204 A- 204 E and the master control unit  202  are preferably pre-programmed to support the functionality described herein without requiring configuration and programming by the user. Preferably, the master control unit  202  includes a plurality of device control buttons  302 A- 302 E. Each of the device control buttons  302 A- 302 E is operable to control one, and only one, of the control devices  204 A- 204 E. For example, a first device button  302 A on master control unit  202  is operable to cause unit  202  to transmit commands to which only the first control device  204 A responds. The second device button  302 B commands the second control device  204 B; the third device button  302 C commands the third control device  204 C; and so forth. 
         [0036]      FIG. 3  illustrates an example master control unit  202  in accordance with the present invention. The example master control unit  202  shown in  FIG. 3  is of the table top variety, plugs into a standard electric outlet, and can be placed anywhere in a home, such as, for example, on a bedside table. As noted above, the master control unit  202  can be provided in other various forms, including as a wall mounted device. The master control unit  202  includes the device buttons  302 A- 302 E, which, when pressed, operate to cause the master control unit  202  to transmit a radio frequency signal and instruct the control device  204 A to turn the electrical device  210 A on or off. The master control unit  202  comprises an “all-on” button  304  (described in greater detail below), which operates to turn on a combination of the control devices  204 A- 204 E to various levels, thereby providing a lighting preset (or “scene”). The master control unit  202  further comprises an “all-off” button  305 , which operates to turn off all of the control devices  204 A- 204 E when pressed. The master control unit  202  further comprises a plurality of status indicators  306 A- 306 E for providing visual feedback about the status of the control devices  204 A- 204 E to a user of system  200 . 
         [0037]      FIG. 4  is a perspective view of the load control device  204 A according to the present invention. The load control device  204 A is equipped with a slider control  402  and an actuator, e.g., a button  404 . Actuation of the button  404  causes the load control device  204 A to toggle an associated lighting load. Adjusting the slider control  402  changes the intensity of the lighting load. An antenna  410  (shown in  FIGS. 5 and 7B ) is preferably provided inside or behind the button  404  and is used for transmitting/receiving radio frequency signals to/from the master control unit  202 , either directly or indirectly via the repeater  206 . The control device  204 A is preferably arranged with a faceplate  406 . The faceplate preferably has a traditional-style opening, such that the faceplate can be used for the control devices  204 A- 204 E as well as a standard mechanical wall switch. According to NEMA Standards Publication ANSI/NEMA, page 7, WD 6-2002, published by the National Electrical Manufacturers Association, Rosslyn, Va., the entire disclosure of which is hereby incorporated by reference, a traditional style opening is a rectangular opening having a minimum width of 0.401±/−0.005 inch, and a minimum length of 0.925±/−0.005 inch. A bezel  407  extends through the opening of the faceplate  406 . The front surface of the bezel is substantially flush with the front surface of the faceplate  406 . 
         [0038]      FIG. 5  is a simplified block diagram of the load control device  204 A. The load control device  204 A is coupled between an AC voltage source  506  and the lighting load  210 A. The load control device  204 A includes a controllably conductive device  510 , such as a bidirectional semiconductor switch, for example, a triac. The controllably conductive device  510  may also be implemented as a relay or another type of semiconductor switch, such as two field effect transistors (FETs) in anti-series connection, a FET in a rectifier bridge, or one or more insulated gate bipolar junction transistors (IGBT). The controllably conductive device  510  has a control input (or gate), which is connected to a gate drive circuit  512 . The input to the gate renders the controllably conductive device  510  selectively conductive or non-conductive, which in turn controls the power supplied to the lighting load  210 A. 
         [0039]    The gate drive circuit  512  provides control inputs to the controllably conductive device  510  in response to command signals from a controller  514 . The controller  514  is preferably implemented as a microcontroller, but may be any suitable processing device, such as a programmable logic device (PLD), a microprocessor, or an application specific integrated circuit (ASIC). A power supply  516  is coupled across the controllably conductive device  510  and generates a DC voltage VCC to power the controller  514 . The power supply  516  is only able to charge when the controllably conductive device  510  is non-conductive and there is a voltage potential developed across the load control device  204 A. 
         [0040]    A zero-crossing detector  518  determines the zero-crossing points of the AC voltage source  506  and provides this information to the controller  514 . A zero-crossing is defined as the time at which the AC supply voltage transitions from positive to negative polarity, or from negative to positive polarity, at the beginning of each line voltage half-cycle. The controller  514  determines when to turn on (or turn off) the controllably conductive device  510  each half-cycle by timing from each zero-crossing of the AC supply voltage. 
         [0041]    A user interface  520  is coupled to the controller  514  and provides a means for receiving inputs from a user and for providing feedback to the user. The user interface  520  preferably includes the button  404  and the slider control  402  as shown in  FIG. 4 . The controller  514  will toggle the state of the lighting load  210 A (i.e., from on to off and vice versa) in response to an actuation of the button  404 . The slider control  402  is operable to provide dimming of the lighting load  210 A. In response to inputs from the slider control  402 , the controller  514  controls the conductive state of the controllably conductive device  510  thereby to affect the dimming level of the lighting load  210 A. 
         [0042]    The load control device  204 A further includes an RF transceiver  522  for transmitting and receiving RF communication signals from the other devices of the system  200  via an antenna  410 . Once the controller  514  receives inputs from the user interface  520 , the controller  514  then controls the lighting load  210 A to the desired level set by the slider control  402 , or to off, and then transmits a radio frequency signal to the master control unit  202  to identify the status of the lighting load  210 A, which may be the intensity of the lighting load, or whether the lighting load is on or off, as determined by the controller  514 . 
         [0043]      FIG. 6  shows an equivalent circuit of the antenna  410  according to the present invention. The antenna  410  is comprised of two parts: a main loop  610  and a feed loop  620 . The main loop  610  is the primary radiating element of the antenna  410  and includes an inductance L and a capacitance C in series. When energized, the main loop  610  resonates at a frequency determined by the values of L and C and enables the transmitting and receiving of RF signals via a radiation resistance, R r , which is a representation of the energy delivered to radiation. A loss resistance, R λ , represents the losses in the main loop  610 . The main loop  610  is primarily magnetically coupled to the feed loop  620 . This coupling is shown schematically in  FIG. 6  by an ideal transformer T. The feed loop  620  includes a magnetizing inductance L m , a leakage inductance L λ , and two ends  630  that connect to the RF transceiver  522 . The feed loop  620  allows for the conduction of signals between the RF transceiver  522  and the main loop  610 . 
         [0044]    In this way, the antenna  410  is adapted to receive RF signals via the main loop  610 , with those radio frequency signals being electromagnetically coupled to the feed loop  620  for input to the RF transceiver  522 . Conversely, the feed loop  620  receives signals to be transmitted from the RF transceiver  522 , electromagnetically couples these signals to the main loop  610  for transmission of RF signals to a master or repeater device. 
         [0045]      FIG. 7A  shows a front view of the load control device  204 A, without the faceplate  406  installed, including a yoke  408 .  FIG. 7B  shows a right side cross-sectional view of the load control device  204 A of  FIG. 7A . An antenna  410  is provided on a printed circuit board inside and behind the button  404  in the plane of the drawing paper. The antenna  410  extends beyond the front surface of the bezel  407  (which is substantially flush with the front surface of the faceplate  406  as shown in  FIG. 4 ). Accordingly, the antenna  410  protrudes through the opening of the faceplate  406  and extends beyond the faceplate. The positioning of the antenna  410  increases the transmission range of the antenna, particularly when the faceplate comprises a metal faceplate. The antenna  410  connects to a dimmer printed circuit board (PCB)  412  that includes the controllably conductive device  510 , the gate drive circuit  512 , the controller  514 , the power supply  516 , the zero-crossing detector  518 , the user interface  520 , and the RF transceiver  522 . The yoke  408  and a back cover  414  enclose the PCB  412 . 
         [0046]    A first side  810 A and a second side  810 B of an antenna  810  for the load control device  204 A according to a first embodiment of the present invention is shown in  FIGS. 8A and 8B , respectively. The antenna  810  includes a main loop trace  820  and a feed loop trace  822  that intersects with the main loop trace. Thus, the main loop of the antenna  810  is not electrically isolated from the feed loop. A capacitor  824  is provided across a break  825  in the main loop trace  820 . The antenna  810  is formed on a printed circuit board and includes three terminals  826 ,  828 ,  830  for connection to the dimmer PCB  412 . The main loop terminates at the two outer terminals  826 ,  828 , while the feed loop is connected to the inner terminal  830 . A main loop trace  820 ′ is provided on the second side  810 B of the antenna  810  and is connected to the main loop trace  820  on the first side  810 A through a plurality of vias  832 . 
         [0047]    The main loop terminals  826 ,  828  are connected to circuit common on the dimmer PCB  412 . The feed loop terminal  830  is connected to the RF transceiver  522  on the dimmer PCB  412 . When a signal is conducted from the transceiver to the feed loop terminal  830 , current flows through the feed loop trace  822 , the main loop traces  820 ,  820 ′, and the main loop terminals  826 ,  828  to circuit common on the dimmer PCB  412 . The main loop is substantially only magnetically coupled to the feed loop, and thus, a current having a larger magnitude is induced in the main loop trace  820  when current flows through the feed loop trace  822 . This current flows through the main loop terminals  826 , the main loop traces  820 ,  820 ′, the capacitor  824 , and the main loop terminal  828 . The main radiating loop  820 ,  820 ′ is positioned in relation to the feed loop  822  such that substantially all of the magnetic flux generated by the current flowing through the feed loop  822  passes through both the area circumscribed by the feed loop  822 , and the area circumscribed by the main loop  820 ,  820 ′. 
         [0048]    An antenna  910  for the load control device  204 A according to a second embodiment of the present invention is shown in  FIGS. 9A and 9B . As shown in  FIG. 9A , a first side  910 A of the antenna  910  includes a feed loop trace  922  that terminates at two terminals  926 ,  930 . A main loop trace  920  is provided on a second side  910 B of the antenna  910  as shown in  FIG. 9B  and is electrically isolated from the feed loop trace  922 . The main loop trace  920  includes a break  925  with a capacitor  924  disposed across the break. A third tab  928  is provided on the PCB of the antenna  910  to aid in connection of the antenna to the dimmer PCB  412 . 
         [0049]    The terminal  926  is connected to circuit common on the dimmer PCB  412 , while the terminal  930  is coupled to an RF transceiver. When a signal is conducted from the transceiver to the feed loop terminal  930 , current flows through the feed loop trace  922  and the terminal  926 . Accordingly, a current is induced in the main loop trace  920  due to the magnetic coupling of the main loop and the feed loop and an RF signal is transmitted from the load control device  204 A. 
         [0050]    Although the words “device” and “unit” have been used to describe the elements of the lighting control systems of the present invention, it should be noted that each “device” and “unit” described herein need not be fully contained in a single enclosure or structure. For example, the master control unit  202  of  FIG. 2  may comprise a plurality of buttons in a wall-mounted device and a processor that is included in a separate location. 
         [0051]    Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. Therefore, the present invention should be limited not by the specific disclosure herein, but only by the appended claims.