Patent Publication Number: US-2010118209-A1

Title: System and method for power saving via context based communication

Description:
FIELD OF THE INVENTION 
     Embodiments of the present invention are generally related to communication devices and systems such as remote control devices, e.g., for remote controlling electronic devices. 
     BACKGROUND OF THE INVENTION 
     As technology advances, display devices such as televisions are being used for an increasing wide variety of activities beyond displaying video, such as web browsing. Correspondingly, remote control devices advanced and added functionality to support in the increase in viewing activities. Further, remote control devices are being used to consolidate the remote controls for a variety of devices including televisions, DVD players, audio systems, home theater computers, and the like. 
     In response to the increased demand for additional capabilities, designers of remote control devices are looking beyond traditional infrared (IR) based remote control technology. One such technology used in remote controls to support an increase in features has been radio frequency (RF) based communication. While RF communication can solve the demand for increased capabilities such as bi-directional communication, etc., RF communication unfortunately uses more power than IR communication and thereby reduces battery life. The addition of a battery charger and/or cradle to a remote control is not advantageous because these devices increase the cost of the remote control. For remote controls using disposable batteries, the batteries will have to be changed more often when RF communication is used. 
     SUMMARY OF THE INVENTION 
     Thus, a need exists for a device that can provide remote control and radio frequency (RF) supported functionality while conserving battery life of the remote control device. Embodiments of the present invention provide a remote control device having radio frequency based communication while saving power. More specifically, embodiments selectively use radio frequency and infrared communication within a remote control device in order to extend battery life. The selection can be context driven. Embodiments conserve power thereby further allowing use of higher power radio frequency communication transmitters/receivers which provide better performance by extending the control range. 
     In one embodiment, the present invention is implemented as a method for generating signals for remote controlling an electronic device (e.g., television, monitor, etc). The method includes receiving an input command for communication to the electronic device and determining a use context based on the input command. Based on the context determination, selective communication over an infrared transmitter and/or a radio frequency transmitter is adjusted for power savings when both transmitters reside within a same remote control device. The input command may then be sent via the infrared transmitter or the radio frequency transmitter. For example, the infrared transmitter may be turned on while the radio frequency transmitter is turned off while not in use. Accordingly, the radio frequency transmitter is selectively used based on the command operations desired by the user thereby saving power. 
     In another embodiment, the present invention is implemented as a system for providing remote control signals to an electronic device. The system includes a first transmitter and a second transmitter each operable to communicate control signals to an electronic device (e.g., display device, television, computer, and the like). The system further includes a control module for controlling the first transmitter (e.g., RF transmitter) and the second transmitter (e.g., IR transmitter). The control module is operable to determine a context in which the electronic device is being used and based on the context, the control module may turn off the first transmitter or the second transmitter. The control module then facilitates communication with the remaining active transmitter. More specifically, for use contexts that can be supported by IR communication, the RF transmitter is turned off and the IR transmitter is used. For advanced use contexts that require the use of the RF transmitter, it is turned on and used. Power savings result from the RF transmitter not being used during use contexts that can be done with the IR transmitter. 
     In this manner, embodiments of the present invention implement a way for remote control of a device while saving power. Thus, more advanced functions than provided by a single traditional transmitter (e.g., IR transmitter) can be supported (e.g., bidirectionality, pointing device functionality, high speed transfer etc.) while having increased battery life. Further by saving power, embodiments allow use of RF transmitter/receiver devices having increased speed and range thereby improving the user experience. 
     In another embodiment, the present invention is implemented as a remote control device. The remote control device includes a radio frequency transmitter operable to communicate control signals to an electronic device (e.g., display device, television, computer, and the like) and an infrared transmitter operable to communicate control signals to the device. The remote control further includes a communication module for controlling the radio frequency transmitter and the infrared transmitter. The control module is operable to determine a use context and based on the context selects the infrared transmitter or the radio frequency transmitter for communications based on power conservation or considerations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements. 
         FIG. 1  shows an exemplary remote control system for providing remote control signals in accordance with one embodiment of the present invention. 
         FIG. 2  shows an exemplary electronic device operable to be remotely controlled in accordance with one embodiment of the present invention. 
         FIG. 3  shows an exemplary communication diagram in accordance with one embodiment of the present invention. 
         FIG. 4  shows a flowchart of a process for controlling an electronic device in accordance with one embodiment of the present invention. 
         FIG. 5  shows a flowchart of an exemplary communication selection process in accordance with one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. While the invention will be described in conjunction with the preferred embodiments, it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims. Furthermore, in the following detailed description of embodiments of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be recognized by one of ordinary skill in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components, and circuits have not been described in detail as not to unnecessarily obscure aspects of the embodiments of the present invention. 
     Notation and Nomenclature: 
     Some portions of the detailed descriptions, which follow, are presented in terms of procedures, steps, logic blocks, processing, and other symbolic representations of operations on data bits within a computer memory. These descriptions and representations are the means used by those skilled in the data processing arts to most effectively convey the substance of their work to others skilled in the art. A procedure, computer executed step, logic block, process, etc., is here, and generally, conceived to be a self-consistent sequence of steps or instructions leading to a desired result. The steps are those requiring physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated in a computer system. It has proven convenient at times, principally for reasons of common usage, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like. 
     It should be borne in mind, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. Unless specifically stated otherwise as apparent from the following discussions, it is appreciated that throughout the present invention, discussions utilizing terms such as “processing” or “accessing” or “executing” or “storing” or “rendering” or the like, refer to the action and processes of a computer system (e.g., system  200  of  FIG. 2 ), or similar electronic computing device, that manipulates and transforms data represented as physical (electronic) quantities within the computer system&#39;s registers and memories into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage, transmission or display devices. 
       FIG. 1  illustrates example components used by various embodiments of the present invention. Although specific components are disclosed in system  100  it should be appreciated that such components are examples. That is, embodiments of the present invention are well suited to having various other components or variations of the components recited in system  100 . It is appreciated that the components in system  100  may operate with other components other than those presented, and that not all of the components of system  100  may be required to achieve the goals of system  100 . 
       FIG. 1  shows an exemplary system for providing remote control in accordance with one embodiment of the present invention. System  100  includes command communication module  102 , control module  108 , optional display  110 , optional preference storage  112 , input module  114 , power source  116 , motion detection module  118 , and communication bus  126 . Communications bus  126  facilitates communication between the components of system  100  including, but not limited to, command communications module  102 , control module  108 , display  110 , preference storage  112 , input module  114 , and motion detection module  118 . In one embodiment, system  100  may be a hand held remote control device. 
     Input module  114  allows entry of commands into system  100  which may then be used to control a device (e.g., system  200 ). Input module  114  may include, but is not limited to, navigations pads, keyboards (e.g., QWERTY), up/down button, touch screen control (e.g., via display  110 ) and the like. 
     Command communication module  102  includes a first transmitter operable to communicate control signals to a device (e.g., system  200 ) and a second transmitter operable to communicate control signals to the device. In one embodiment, command communication module  102  includes IR transmitter  104  and radio frequency (RF) module  106 . RF module  106  includes transmitter  106 a and optional receiver  106 b. Command communication module  102  may further include a radio frequency based receiver which is optional. It is appreciated that command communication module  102  may include a radio frequency transceiver. It is further appreciated that embodiments of the present invention may use a variety of wireless communication formats or protocols including, but not limited to, 802.11a/b/g/n, Bluetooth, Z wave, or other wireless standards or protocols. 
     It is appreciated that control module  108  may control the first transmitter and the second transmitter. Control module  108  includes microprocessor  120  and use context detector  124 . Microprocessor  120  is used to determine use context via use context detector  124  and control command communication module  102 . Use context detector  124  determines a context based on user interaction (e.g., key or button presses). Control module  108  is operable to determine a use context of device  100  and based on the use context, turn off the first transmitter or the second transmitter and continuing communication with the remaining active transmitter. The same may be true for the receivers. In one exemplary embodiment, the use context may be based on a button or series of buttons pressed on the remote  200  or based on selections on the device (e.g., on-screen selections). 
     In one embodiment, one use context is an operating mode having a pointing or cursor mode. Thus, if there is a selection of a command or function making use of device  200  as a pointing device then control module  108  switches over to RF communication. System  100  operating as in a pointing or cursor mode may be facilitated by motion detection module  118 . Motion detection module  118  may include multi-axis accelerometers to detect direction, speed, and acceleration which can be translated into position. For example, for regular television viewing, button presses may be sent via IR from device  100  but when web surfing, executing computer applications, interacting with an operating system, navigating an EPG with a cursor or other cursor based navigation commands are received, the IR may be disabled or only selectively used while RF transmitter  106   a  is active and outputting the directional (e.g., pointing) commands to the device. During this use context, bidirectional RF communication may be enabled. 
     Power source  116  provides power for system  100 . Power source  116  may be portable power source including, but not limited to, batteries, rechargeable batteries (e.g., lithium ion, nickel metal hydride, nickel-cadmium, etc.) 
     Embodiments of the present invention may facilitate pointing or cursor manipulation (e.g., a remote control being used as a cursor device) via use of accelerometers or gyroscopes. It is appreciated that the nature of radio frequency communication relative to an infrared transmitter may be advantageous for quickly (e.g., high speed) transmitting increased amounts of information associated with accelerometers and gyroscopes. Also, a wider range of remote movement is allowed with RF communication as it is not line of sight, as with IR communication. 
     The use context may also include keyboard or keystroke commands. For example, control module  108  may switch to RF communication from IR communication for transmitting keystrokes for accuracy and based on the amount of keystrokes. 
     In one embodiment, control module  108  may switch to communication via RF transmitter  106  for use modes when line of sight is no longer available (e.g., when IR signals can no longer be received by system  200 ). If this use context is detected, then RF communication may be enabled. 
     The use context may further include a request to download an electronic programming guide (EPG) to system  100  (e.g., a remote control). RF radio frequency receiver  106 b of RF module  106  may be operable to receive an electronic programming guide. For example, system  100  may include a display  110  operable to display an EPG downloaded to system  100 . System  100  may then allow a user to browse the EPG while the user is also watching television or another video source. RF communication may be used based on bidirectional communication and speed of transfer. After the EPG has been downloaded to system  100 , RF module  106  may be turned off and IR communication restored. The turning off RF module  106  conserves power. RF based receiver  106  may remain off until either the current EPG becomes obsolete (e.g., times listed in the EPG are no longer valid) or the user requests a new EPG (e.g., via an EPG button). Correspondingly, the selection (e.g., music channel, video channel, pay per view, etc.) from the EPG may be transmitted via IR communication. 
     Preference Storage  112  stores preference information. In one embodiment, user preferences including a pointing device mode preference (e.g., for navigation of an electronic programming guide (EPG)) may be stored in preference storage  112 . System  100  may thus turn off IR transmitter  104  and turn on RF module  106  when the use context includes a user preference thereby activating the RF receiver on the device to be controlled (e.g., device  200 ). In another embodiment, preferences are stored on the device being controlled (e.g., preference storage  118  of system  200 ), system  100  receives notification of the change in mode. For example, a television could wake up or activate the RF transmitter in a remote control which may be configured to scan for signals that communication should be switched from IR communication (e.g., a low duty cycle circuit). Alternatively, IR communication from device  100  may request the RF section of the system  200  (e.g., RF receiver  212 ) be enabled, while switching to communication via RF transmitter  106   a . Upon receiving the acknowledgement of transmitter  220 , IR transmitter  104  may be disabled. 
     It is appreciated that when one or more of the above described use contexts is determined to be over, embodiments herein disable RF communication and resume IR communication thereby saving power. It is further appreciated that within a use context when RF is enabled, system  100  may till enable IR communication as a second communication pathway. 
     In one embodiment, system  100  may be a remote control device including a radio frequency (RF) transmitter operable to communicate control signals to a device and an infrared transmitter operable to communicate control signals to a device. The communication module of the remote control device controls communication of the RF transmitter, RF receiver, and the infrared transmitter. System  100  may further include an RF receiver. The communication module is operable to determine a use context and based on the use context selectively use the infrared transmitter or the RF transmitter and/or RF receiver for communication based on power conservation. 
     The RF transmitter and RF receiver of a remote control may facilitate bidirectional communication (e.g., EPG downloads, secure communication, preference communication). The radio frequency receiver may further facilitate user feedback on the remote control based on on-screen controls, (e.g., vibrations, color changes, etc.) as user moves a pointing device around. Bidirectional communication may also be used when a new device (e.g., DVD player) is installed which announces the presence of the new device presence and tells the remote what settings and configurations to use. 
     In this fashion, embodiments of the present invention implement a process to provide radio-frequency-based supported functionality while conserving battery life. More specifically, embodiments of the present invention may selectively use radio frequency communication in order to conserve power. For example, relatively lower power IR communication is used for most television commands while RF communication is used for advanced functionality (e.g., high speed, bidirectional communication, and when wide range remote control movement is required). Thus, embodiments of the present invention extend battery life. By reducing overall power consumption, embodiments may further allow use of an increased power RF based receiver and/or transmitter thereby facilitating increase range, speed, and improved payload. 
       FIG. 2  illustrates exemplary components used by various embodiments of the present invention. Although specific components are disclosed in system  200  it should be appreciated that such components are examples. That is, embodiments of the present invention are well suited to having various other components or variations of the components recited in system  200 . It is appreciated that the components in system  200  may operate with other components than other those presented, and that not all of the components of system  200  may be required to achieve the goals of system  200 . It is appreciated that embodiments of system  200  include a variety of electronic devices that can be controlled remotely, including but not limited to computers, display devices, televisions, cathode ray tube (CRT) displays, computer monitors, liquid crystal displays (LCDs), plasma displays, projection displays, projectors, portable devices, game consoles, and handheld devices, etc. 
       FIG. 2  shows an exemplary device operable to be remotely controlled in accordance with one embodiment of the present invention. System  200  includes content receiver  202 , display controller  204 , display screen  206 , command receiver  208 , command processor  214 , audio controller  216 , and preference storage  218 , transmitter  220 , cable or satellite connection  222 , internet connection  224 , and wireless antenna  226 . 
     Content receiver  202  receives content for system  200 . Receiver  202  may receive signals including content from a variety of sources including, but not limited to, computers, computer networks, portable devices, set top boxes, over the air broadcasts, cable broadcasts, satellite broadcasts, Digital versatile Discs (DVDs), Blu-ray discs, Digital Video Broadcasting-Handheld (DVB-H), Digital Multimedia Broadcasting (DMB), Digital Video Broadcasting Satellite services to Handhelds (DVB-SH), Digital Audio Broadcasting (DAB), Digital Video Broadcasting IP Datacasting (DVB-IPDC), Internet Protocol Television (IPTV), etc. Content receiver  202  may receive content (e.g., electronic programming guide information and other content) via cable or satellite connection  222 , internet connection  224 , and wireless antenna  226  (e.g., via 802.11a/b/g/n, Bluetooth, Z wave, Digital Broadcast, etc.). 
     Display controller  204  controls display screen  206  of system  200 . Display controller  204  may control a variety of display screens associated with system  200 , including but not limited to, CRTs, LCDs, plasma displays, projection based, and Digital Light Processing (DLP) displays. 
     Command receiver  208  receives commands. Command receiver  208  may receive commands via a variety of receivers including, but not limited to, infrared receiver and radio frequency receivers. The commands may have been issued via a remote control (e.g., system  100  of  FIG. 1 ). In one embodiment, command receiver  208  includes an infrared (IR) receiver  210  and a radio frequency (RF) receiver  212 . 
     Command processor  214  processes commands received by system  200  via command receiver  208 . The commands received are processed and executed by system  200 . For example, control codes (e.g., increase volume, change channel, launch an application, launch web browser, etc.) may be received by via an infrared receiver  210  or radio frequency receiver  212 , decoded, and sent to the command processor  214 . 
     Audio controller  216  controls audio output for system  200  including a variety of outputs including, but not limited to, 2, 2.1, 3.1, 5.1, 6.1, 7.1, and 8.1 channel audio. The audio content may be received via content receiver  202 . It is appreciated that audio controller  216  may output to audio equipment integrated within system  200 . 
     Preference Storage  218  may store user preferences. In one embodiment, user preferences including a pointing device mode preference (e.g., for navigation of an electronic programming guide (EPG)) may be stored. 
     Transmitter  220  may send signals to a control device (e.g., remote control). The signals may include, but are not limited to, acknowledgments, EPGs (e.g., for download to a remote control) encrypted information, and information based on on-screen selections. 
       FIG. 3  shows an exemplary communication sequence  300  between a remote control unit  302  (e.g., system  100 ) and display device  304  (e.g., system  200 ) in accordance with one embodiment of the present invention. It is appreciated that the communications between control unit  302  and display device  304  may occur via a variety of interfaces including, but not limited to, an infrared transmitter/receiver and a radio frequency (RF) transmitter/receiver, etc. 
     At step  301 , an input command is received by control unit  302 . The input command may originate from a button or key press on control unit  302 . 
     At step  306 , the input command is sent to display device  402 . As described herein, the input command may be sent via infrared unless control unit  302  is in a mode where RF communication is optimal. For example, normal television functions may be sent via infrared while a command of a pointing device mode may be sent via RF communication. At step  306 , if IR communication is used, then the RF transmitter is disabled. 
     At step  308 , a request for an electronic programming guide (EPG) is sent by control unit  302  to display device  304 . In one embodiment, control unit  302  (e.g., remote control) includes a display (e.g., display  110 ) operable to display an EPG and facilitate selection of content within the EPG (e.g., via touch screen interaction or button selection). Control unit  302  may send the request for the EPG via an IR interface or an RF interface. If the RF interface is off prior to the request to display device  304 , the RF interface may be activated in recognition of an EPG use context that require RF communication. 
     At step  310 , display device  304  sends the EPG or content to control unit  302 . In one embodiment, the EPG is sent to control unit  302  via an RF interface because of the speed of transfer and bidirectional nature. After control unit  302  has received the EPG, the RF interface may be deactivated and the IR interface reactivated. Control unit  302  may further receive content for viewing or previewing on control unit  302  (e.g., internet browsing, television transmission viewing, etc.). 
     At step  312 , a control signal with the EPG selection is sent via IR communication. Control unit  302  sends the selection from the EPG via infrared to conserve power. 
     At step  314 , control unit  302  requests to enter an electronic commerce (e-commerce) mode. In one embodiment, the e-commerce mode may be entered via a user pressed button on control unit  302  (e.g., shopping button). 
     At step  316 , display device  304  sends an acknowledgement of the request to enter an e-commerce mode. The acknowledgement may be part of a process to establish and maintain a secure connection between control unit  302  and display device  304  (e.g., handshaking, encryption, verification of trusted devices, etc.). The device  302  recognizes the e-commerce request as a special mode that requires RF communication and enabled the RF transmitter. 
     With reference to  FIGS. 4 and 5 , flowcharts  400  and  500  illustrate example functions used by various embodiments of the present invention. Flowcharts  400  and  500  include processes that, in various embodiments, are carried out by a processor (of  FIG. 1 ) under the control of computer-readable and computer-executable instructions which may be stored on a computer-readable medium. Although specific function blocks (“blocks”) are disclosed in flowcharts  400  and  500 , such steps are examples. That is, embodiments are well suited to performing various other blocks or variations of the blocks recited in flowcharts  400  and  500 . It is appreciated that the blocks in flowcharts  400  and  500  may be performed in an order different than presented, and that not all of the blocks in flowcharts  400  and  500  may be performed. 
       FIG. 4  shows a flowchart of a process for controlling a device in accordance with one embodiment of the present invention. The portions of flowchart  400  may be carried out by a remote control unit (e.g. system  100 , control unit  302 , or remote control). 
     At block  402 , a system (e.g., system  100 ) operates in a regular mode. In one embodiment, the regular operating mode is a mode where the system communicates (e.g., sends TV control commands) via infrared communication and the RF transmitter is disabled. 
     At block  404 , an input command from a user for communication to a device is received. As described herein, the input command may be a variety of commands including, but not limited to, basic television commands (e.g., volume up/down, channel up/down, menu, input/source selection, etc.), web browsing or internet mode, electronic programming guide (EPG), or keystroke (e.g., from a QWERTY keyboard). 
     At block  406 , a use context is automatically determined based on the input command and a set of recognized functions that are stored by the remote device. As described herein, the use context can include a pointing device mode (e.g., web browsing/surfing, computer or operating system, accelerometers or gyroscope based mode), preference settings, an EPG request, an e-commerce request, or a mode needing a bidirectional communication, or regular television mode. For example, the preference settings could include whether a user navigates an EPG with traditional remote control buttons (e.g., arrow buttons or a navigation pad) or a cursor/pointing style mode. In one embodiment, the preference settings may be stored in a memory accessible by a control unit (e.g., control unit  302  or a remote control). In another embodiment, the preference settings may be stored on the device to be controlled (e.g., display device, television, and the like). 
     The use context can further include a keyboard mode (e.g., for email composing, uniform resource locator (URL) entry, text messaging, instant messaging). Embodiments of the present invention may have hard keyboards including a full keyboard (e.g., QWERTY keyboard) or could be a soft keyboard (e.g., on screen keyboard on control device with a touch screen display). RF communication may be particularly better suited for transmitting keystrokes for accuracy and the amount of keystrokes. Further, the use of both thumbs for entering data might preclude accurate pointing for an infrared remote control at a receiver in a device. 
     At optional block  408 , a signal is received from a device. The device may be a display device and as described herein, may be indicating a change in the mode. For example, a television could indicate to a remote control via RF communication that a selection has been made to enter a web browsing mode or pointing device mode (e.g., for an EPG based on a stored preference). The signal of  408  can be used to perform the use content determination, in one embodiment. 
     At block  410  based on the use context determination, communication over an infrared transmitter and a radio frequency transmitter is adjusted for power savings. 
     At block  410   a , the radio frequency transmitter is activated for sending the input command. At block  410   b , the infrared transmitter is deactivated in order to save power. For example, when a pointing device mode or other mode where RF communication is optimal is determined, the RF transmitter which was off to conserve power is turned on for the transmission of the input command. It is appreciated that the RF transmitter may remain on as long as input commands that are optimally sent via RF communication are received. 
     At block  410   c  the use context is complete and the radio frequency transmitter is deactivated thereby reducing the power used. At block  410   d , the infrared transmitter is turned on thereby allowing communication of an input command at less power than via the RF transmitter. For example, if a user has pressed a button to go back to watching TV, the command can be communicated via IR and the RF transmitter can be deactivated to conserve power. It is appreciated that the IR transmitter may remain on while commands that may be sent over IR are received. 
     At block  412 , the input command is transmitted via the infrared transmitter or the radio frequency transmitter. At block  412   a , the command is transmitted via RF communication. At block  412   b , the command is transmitted via IR communication. 
       FIG. 5  shows a flowchart of an exemplary communication selection process in accordance with one embodiment of the present invention. The processes of flowchart  500  may be carried out by a remote control unit (e.g. system  100 , control unit  302 , or remote control). 
     At block  502 , a remote control is in an IR on and RF off mode. In one embodiment, this mode may be a default mode. 
     At block  504 , a key press is received. As described herein, the key press may be from a navigation pad, keyboard, and the like. 
     At block  506 , a use context determination is performed. As described herein, the use context is determined based on the key press and the functionality associated with the key press (e.g., pointing device mode, television control, etc.). 
     At block  508 , an RF communication module is turned on. As described herein, RF communication may be used for a pointing device mode, e-commerce mode, bi-directional mode, and the like. 
     At block  510 , RF communication is turned off and IR communication is turned on. As described herein, IR communications may be used for video remote control features (e.g., volume, channel, display settings, etc.). 
     At block  512 , the use context ends. As described herein, the use context may end when a command is transmitted to a device to be controlled (e.g., system  200 ). 
     At block  514 , RF communication is turned off when the use context utilizing RF communication is over. RF communication may be turned off to conserve power. 
     The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.