Abstract:
An apparatus and method for ensuring proper antenna position of a cordless communication device having a retractable antenna, including a detector such as a light sensor or induction coil for detecting the antenna position, and an indicator for providing audio and/or visual indication of the antenna position.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention is directed toward a communication device, and more particularly toward a cordless communication device having an antenna. 
     2. Background Art 
     A cordless communication device having a retractable antenna, for example a cellular telephone, receives and transmits signals using the retractable antenna. The communication device operates whether the retractable antenna is in an extended position or a retracted position but, when the antenna is in the extended position, maximum performance is achieved. For example, in a cellular telephone, an antenna rod and an antenna coil mounted on the cellular telephone at a base of the antenna rod radiate the signal from the communication device, providing the ability for maximum performance. However, while the antenna is in the retracted position, minimum performance may be realized. For example, for the cellular telephone, only the antenna coil radiates the signal from the cellular telephone, potentially minimizing performance. Such degraded performance is often disappointing to a user of the cordless communication device. 
     The present invention is directed to overcoming the problem discussed above. 
     SUMMARY OF THE INVENTION 
     In one aspect of the present invention, a cordless communication device including a retractable antenna includes a detector mounted to the cordless communication device for detecting the antenna position and a controller coupled to the detector for determining the antenna position responsive to the detector. An indicator is coupled to the controller for indicating the antenna position. 
     In one form of this aspect, the detector includes a light emitting diode (LED) for emitting light and a photosensor positioned to sense the LED emitted light when the antenna is in the extended position, and to not sense the LED emitted light when the antenna is in the retracted position. In a further form, the LED is mounted adjacent the photosensor on an inner surface of the electronic device. In a further form, the inner surface is a first inner surface, and a reflector is mounted on a second inner surface for reflecting the emitted light to the photosensor, wherein the reflector, LED and photosensor are relatively positioned such that the emitted light reaches the photosensor when the antenna is in the extended position, and the emitted light does not reach the photosensor when the antenna is in the retracted position. 
     In another form, the detector includes a coil positioned to change an inductance of the coil when the antenna is placed in the extended position. 
     In yet another form, the cordless communication device is a cellular telephone. 
     In another form, the detector detects the antenna position only at a beginning of a call. 
     In another form of the present invention, the indicator is a speaker, and the controller is adapted to block operation of the speaker when the antenna is in the retracted position. 
     In another form, the indicator is a speaker, and the controller is adapted to provide an audible signal using the speaker when the antenna is in the retracted position. 
     In yet another form, the indicator is a display for displaying the antenna position. 
     In another aspect ofthe present invention, a method for indicating an antenna position of a cordless communication device having a retractable antenna is provided, including detecting the antenna position, and responsive to the detecting, providing an indication of the antenna position when the antenna is in a retracted position. 
     In a form of this aspect ofthe present invention, the detecting includes emitting light from an LED, and sensing for the emitted light at a photosensor, where the emitted light reaches the photosensor when the antenna is in the extended position, and the emitted light does not reach the photosensor when the antenna is in the retracted position. In a further form, the sensing for emitted light includes reflecting the emitted light from a reflector toward the photosensor. 
     In another form ofthe present invention, the detecting includes detecting inductance of a coil proximately spaced from the antenna. In a further form, a current is provided through the coil. 
     In another form, the cordless communication device is a cellular telephone, and the detecting is done only when a call is initiated. 
     In yet another form, providing an indication includes displaying the antenna position on a visual display for the communication device. 
     In another form ofthis aspect, providing an indication includes disabling a speaker for the communication device when the antenna position is detected as the retracted position. 
     In yet another form of this aspect, providing an indication includes providing an audible signal using a speaker for the communication device when the antenna position is detected as the retracted position. 
     It is an object of the present invention to improve performance of the cordless communication device. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an illustration of a cordless communication device having a retractable antenna in accordance with an embodiment of the present invention; 
     FIG. 2 a  is a simplified partial cross section of a first embodiment taken along line  2 — 2  of FIG. 1, where the antenna is retracted; 
     FIG. 2 b  is a simplified partial cross section similar to FIG. 2 a  but with the antenna extended; 
     FIG. 3 a  is a simplified partial cross section similar to FIG. 2 a  but of an alternate embodiment; 
     FIG. 3 b  is a simplified partial cross section of the FIG. 3 a  embodiment with the antenna extended; 
     FIG. 4 a  is a schematic diagram of the FIGS. 3 a - 3   b  embodiment with the antenna retracted; 
     FIG. 4 b  is a schematic diagram of the FIGS. 3 a - 3   b  embodiment with the antenna extended; and 
     FIG. 5 is a flowchart illustrating the method of operation of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 is an illustration of a cordless communication device, here a cellular telephone  100 , having a retractable antenna  110  in accordance with an embodiment of the present invention. The cellular telephone  100  includes an antenna base  120  against which the retractable antenna  110  rests when in the retracted position. The antenna base  120  typically includes an antenna coil  125 , which serves to transmit and receive information for the cellular telephone  100  when the antenna  110  is retracted. 
     The cellular telephone  100  further includes a speaker  130  which provides audible information to a user, and a display device  140 , which provides visual information to the user. The speaker  130  and/or the display  140  are suited to serve as an indicator for indicating the antenna  110  position, as discussed below. 
     FIGS. 2 a  and  2   b  show a simplified partial cross-section ofthe cellular telephone  100  along line  2 — 2  of FIG.  1 . FIG. 2 a  shows a cross section where the retractable antenna  110  is retracted in accordance with an embodiment of the present invention. FIG. 2 b  shows a cross section where the antenna  110  is extended in accordance with an embodiment of the present invention. 
     A printed circuit board (PCB)  200  is mounted within the cellular telephone  100 . A controller  210  is mounted on the PCB  200 , and is coupled to the speaker  130 , the display  140  and a detector, here shown as a light-emitting diode (LED)  220  and a photosensor  230 . Although no physical connection is shown between the controller  210  and the LED  220  and photosensor  230 , the connection exists via the PCB  200 . A reflector  240  is mounted on an interior wall  280  of the cellular telephone  100  opposite the LED  220  and the photosensor  230 . The LED  220  and the photosensor  230  are positioned on the PCB  200  relative to the antenna  110  such that the antenna  110 , in its retracted position, blocks light emitted by the LED from being detected by the photosensor  230 . 
     The PCB  200  further includes a PCB coupler  250  which couples the PCB  200  to the antenna coil  125  while the antenna  110  is retracted. The PCB coupler  250  couples the PCB  200  to both the antenna coil  125  and the antenna  110  via an antenna coupler  260  when the antenna is in the extended position shown in FIG. 2 b.    
     In operation, light emitted by the LED  220  is blocked by the antenna  110  when the antenna is in the retracted position, as shown in FIG. 2 a . The controller  210  is suitably programmed to determine that the antenna is in the retracted position when the controller  210  does not receive a signal from the photosensor  230  indicating that the emitted light from the LED  220  is detected at the photosensor  230 . The controller  210  is further suitably programmed to provide an indication via at least one ofthe speaker  130  and the display  140 . Where the speaker  130  provides the indication, the indication may be an audible signal such as a “beep” or other tone, or may be a pre-recorded message stored in a suitable memory (not shown) in the cellular telephone  100  and sent to the speaker  130  via the controller  210 . The message may be, for example “antenna not extended”. Where the indication is provided by the display  140 , such as a liquid crystal display (LCD), the indication may be a written message, for example “antenna not extended” written on the display  140 , or could be a flashing symbol likely to attract the attention of the user. 
     When the antenna  110  is extended, shown in FIG. 2 b , light emitted by the LED  220 , designated by the arrow  270  is reflected from the reflector  240 , and reflected light designated by an arrow  280  is received at the photosensor  230 . The controller  210 , being coupled to the photosensor  230  receives a signal from the photosensor  230  that the light emitted by the LED  230  is detected, thereby indicating that the antenna  110  is in the extended position. 
     In a further embodiment, the controller  210  is suitably programmed to cause the LED  220  to emit light only when a call is initiated, for example when the user of the cellular telephone  100  is placing a call, or receiving a call. The controller  210  may direct the LED  220  to stop emitting light when the antenna  110  is extended, or when the call is completed. 
     In a further embodiment, the controller  210  may provide the indication via the speaker  130  by disabling operation of the speaker  130  until the antenna  110  is placed into the extended position. Once the antenna  110  is placed into the extended position, the controller  210  enables the speaker  130 . 
     In a further embodiment, one skilled in the art would realize that, depending on the sensitivity of the photosensor  230 , and the type of LED  220  used, a reflector  240  may not be necessary, as the emitted light from the LED  220  may be received at the photosensor  230  when the antenna  110  is extended without use of the reflector  240 . For example, the inner wall  280  of the cellular telephone  100  may be sufficiently reflective for reflecting light emitted by the LED  220  to the photosensor  230 . 
     In a further embodiment (not shown), where the antenna  110  is guided via a sleeve within the cellular telephone  100 , the sleeve may have holes bored there-through, sufficient for the photosensor  230  to detect light emitted by the LED  220  when the antenna  110  is in the extended position. 
     In a further embodiment not shown, where the antenna is guided by the sleeve, the sleeve may be formed from a transparent or semi-transparent material sufficient for the light emitted by the LED  220  to be detected at the photosensor  230  when the antenna  110  is in the extended position. 
     Having the LED  220  and the photosensor  230  for detecting the position ofthe antenna  110  provides improved performance to the user of the cellular telephone  100 , as an indication is provided to the user when the antenna  110  is not in the extended position. Further, having the controller  210  cause the LED  220  to emit light only at the beginning of a call conserves battery power. Additionally, having the speaker  130  and the display  140  provide the user with the indication of the antenna position, thereby directing the user to extend the antenna  110  to achieve maximum potential performance. 
     In an alternate embodiment of the invention shown in FIGS. 3 a  and  3   b , a coil, or inductor  300  is mounted on the PCB  200  and coupled to the controller  210  via the PCB  200 . An inductance change across the coil  300  caused by the antenna  110  allows the controller  210  to determine the antenna position  110  as being retracted (FIG. 4 a ) or extended (FIG. 4 b ) as discussed below. Where the controller  210  determines that the antenna  110  is in the retracted position, indications as discussed above may be provided to the user ofthe cellular telephone via the speaker  130  and the display device  140 . 
     FIGS. 4 a  and  4   b  show electrical schematic diagrams of the cellular telephone  100  for implementing the detector using the coil  300 . An oscillating current source  400  provides an oscillating current “I” through a resistor  410 . The oscillating current source  400  may be provided by the controller  210 , or by a suitable oscillating current source within the cellular telephone  100 . A voltage node  420  coupled to an output of the resistor  410  provides a voltage reading across the coil  300 . The voltage node  420  may be coupled to the controller  210 . 
     In operation, when the antenna  110  is in the retracted position (FIG. 4 a ), a voltage, E, at the voltage node  420  impressed across the coil  300  is: 
     
       
         E=2πfLI 
       
     
     where f is the frequency of the oscillating current source  400  in hertz, L is the value of the inductor and the mutual inductance caused by the antenna  110 , and I is the current supplied by the oscillating current source  400 . When the antenna  110  is in the extended position, FIG. 4 b , the inductance of the coil  300  changes to L′, thereby causing a voltage E′ to be present at the voltage node  420  to be: 
     
       
         E=2πfL′I 
       
     
     where f is the frequency of the oscillating current source in hertz, L′ is the value of the inductor without the mutual inductance caused by the antenna  110 , and I is the current supplied by the alternating current source  400 . 
     The controller  210  senses the voltage provided at the voltage node  420 , and thereby determines the position of the antenna  110  as being extended or retracted. The controller  210  may accomplish this using a memory table indexed by voltage values. A first voltage value of approximately E in the memory table indicates the retracted antenna position, and a second voltage value of approximately E′ in the memory table indicates the extended antenna position. The voltage measurement can be done using an analog to digital converter (not shown) and comparing the digital voltage value to the memory table to determine the antenna position. Alternatively, the voltage measurement may be done in the analog domain using rectification and feeding the output to a comparator (not shown) and comparing the analog voltage measurement to a reference, where the output from the comparator indicates to the controller the antenna position. 
     The value of the current provided by the oscillating current source  400  is determined experimentally as would be known by one skilled in the art, based on a size of the coil  300 , antenna  110  construction, and distance of the coil  300  from the antenna  110 . Typically, the current provided by the oscillating current source  400  will be a very small value in the order of magnitude of microamps, and therefore may be active at all times without significant drain on the battery. 
     Thus, having the coil  300  as the detector provides a detector which may be active at all times without significantly draining the battery. Further, where an antenna sleeve guides the antenna  110 , the coil  300  provides a detector which may detect the antenna position of the antenna  110  without a specialized antenna sleeve, for example a transparent antenna sleeve or one with holes bored therethrough. 
     It should be understood that in its broadest scope, the detector could be in forms other than the embodiments shown in FIGS. 2 a - 4   b , and that any structure capable of detecting the antenna position and causing the controller to generate an indication such as described herein when the antenna is retracted could be used within the broad scope of this invention. 
     FIG. 5 is a flowchart illustrating operation of an embodiment of the present invention. In step  500 , it is detected whether the “yes” key is pushed on the cellular telephone  100 , thereby indicating an initiated call. Where the “yes” key is pushed, the antenna position is detected as shown in step  510 . This may be accomplished as discussed above using the LED  220  and photosensor  230 , or using the coil  300  or other suitable detectors. In step  520 , it is determined whether the antenna  110  is extended. This is accomplished, for example, by the controller  210  determining whether light was detected at the photosensor  230  where the LED  220  and photosensor  230  are the detector, or by determining from a voltage change at the voltage node  420  where the coil  300  is the detector. If it is determined that the antenna is extended, the call continues as normal, shown in step  530 . However, if it is determined that the antenna is not extended, the method proceeds to step  540  where an indication is provided. The indication may be provided via the speaker  130  and/or the display  140  as discussed above. It is then determined in step  550  whether the “no” key is pushed, indicating that the call is ended. Where the “no” key is pushed, the method returns to step  500  and proceeds as previously discussed. If however, the “no” key is not pushed, the method returns to step  510  and proceeds as previously discussed. 
     Still other aspects, objects, and advantages of the present invention can be obtained from a study of the specification, the drawings, and the appended claims. It should be understood, however, that the present invention could be used in alternate forms where less than all ofthe objects and advantages of the present invention and preferred embodiments as described above would be obtained.