Abstract:
A portable communication device has an apparatus housing with a movable element attached thereto and a sensor for detecting a position of the movable element in relation to the apparatus housing. The communication device also has an electrodynamic device having a magnet. The sensor is arranged to detect the magnetic field originating from the magnet in the electrodynamic device and to provide an output which is relative to the apparatus housing. A device is provided, in the movable element, for conducting the magnetic field from the electrodynamic device to the sensor.

Description:
TECHNICAL FIELD 
     The present invention relates to a portable communication device, comprising an apparatus housing with a movable element attached thereto and a sensor for detecting a position of the movable element in relation to the apparatus housing, the communication device further being provided with electrodynamic means comprising a magnet, and the sensor being arranged to detect the magnetic field originating from the magnet in the electrodynamic means and to provide an output, which is related to the position of the movable element relative to the apparatus housing. 
     BACKGROUND 
     Portable communication devices comprising a movable element attached to an apparatus housing are known as such from e.g. EP-B-0 275 996, JP-A-08065368, JP-A-06303296, U.S. Pat. No. 5,384,844, U.S. Pat. No. 5,257,310 and EP-A-0 120 418. As seen in these prior art documents, portable communication devices as described above are available in many different kinds, such as mobile or cellular telephones, wireless telephone handsets, etc. 
     In the case of mobile telephones the movable element usually has the form of a flip, which is pivotally or slidably mounted, by means of for instance a hinge mechanism, to the main apparatus housing of the telephone. The flip is movable between two end positions. In the first position the flip is fully folded in or displaced in close proximity to a portion of the apparatus housing, normally the portion at which a key pad is located, the flip thereby protecting the key pad from accidental actuation. The second end position of the flip is a fully opened or extended position, wherein the entire front surface of the telephone is accessible to a user during e.g. ongoing calls. Furthermore, as is well known in the technical field, the mobile telephone comprises audio-generating means, such as a speaker with a voice coil and a magnet for exposing the voice coil to a magnetic field, and/or a buzzer (summer) for generating audio signals indicative of e.g. an incoming call. Additionally, the telephone may comprise an electrodynamic vibrator with a similar function. 
     It is often desired to detect the current position of the flip relative to the apparatus housing. For instance, the processor (CPU) of the mobile telephone may be arranged to control the enlightening of the display and the key pad, once the flip is moved from its closed position to its open or extended position. Additionally, when the flip is folded in from its open position, the processor may be arranged to control the termination of an ongoing call (i.e. to perform an on-hook operation). For the purpose of detecting the position of the flip and the reporting thereof to the processor, it is previously known to provide the mobile telephone with a magnetic sensor, such as a hall element or a reed switch, in the apparatus housing, while the flip is provided with a magnet. The location of the magnet in the flip relative to the hall element or reed switch in the apparatus housing is such that, when the flip is closed or folded in, the distance between the magnet and the magnetic sensor is short enough for the latter to detect the presence of the magnetic field generated by the former. On the other hand, when the flip is opened or folded out, the distance between the magnet and the magnetic sensor is considerably larger and particularly too large for the magnetic sensor to be able to detect the magnetic field from the magnet. Hence, in this way the mobile telephone is able to detect the position of the flip relative to the main apparatus housing. 
     The drawback of the prior art approach is that the need for a separate magnet in the flip implies a cost penalty as well as difficulties in mounting the magnet in a satisfactory way in the flip, since the magnet will have to be large enough for generating a sufficiently strong magnetic field. 
     U.S. Pat. No. 5,673,314 discloses a mobile telephone having a speaker with a magnet, both of which are located in the flip and are arranged to magnetically affect a switch located in the telephone housing. Hence, the magnetic field generated by the speaker magnet is used for detecting the position of the flip, wherein the need for a separate magnet is eliminated. 
     The drawback of the solution shown in U.S. Pat. No. 5,673,314 is that the location of the speaker in the flip requires electrical wiring between the telephone housing and the flip. Such electrical wiring is volnerable to e.g. dirt, moisture and mechanical damage. 
     SUMMARY 
     The object of the present invention is to eliminate the drawbacks of the portable communication devices of the prior art, as described above. 
     More specifically, the object of the present invention is to provide a portable communication device having an apparatus housing and a movable element (such as a flip), wherein the position of the movable element may be detected without any separate magnet and wherein electrical wiring between the apparatus housing and movable element is avoided. 
     The object is achieved for a portable communication device, such as a mobile telephone, comprising an apparatus housing with a movable element, such as a flip, attached thereto and a sensor for detecting a position of the movable element in relation to the apparatus housing, the communication device further being provided with electrodynamic means comprising a magnet, such as a speaker, a buzzer and/or a vibrator, and the sensor being arranged to detect the magnetic field from the magnet in the electrodynamic means so as to provide an output, which is related to the position of the movable element relative to the apparatus housing, by the provision of means in the movable element for conducting the magnetic field from the electrodynamic means to the sensor. 
     Other objects, advantages and features of the present invention appear from the following detailed description, from the drawings as well as from the appended patent claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will now be described in more detail in the following, reference being made to the accompanying drawings, in which: 
     FIG. 1 is a schematic perspective view of a portable communication device in the form of a mobile telephone according to a preferred embodiment of the present invention, 
     FIG. 2 is a schematic side view of the device of FIG. 1, wherein a movable element assumes an open position, and 
     FIG. 3 is a schematic side view of the device of FIG. 1, wherein the movable element assumes an almost closed position. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 illustrates a portable communication device in the form of a mobile telephone  10  according to a preferred embodiment of the present invention. The mobile telephone  10  comprises an apparatus housing  12 , to which a movable flip  14  is pivotally mounted by means of a hinge mechanism  26 . The telephone  10  comprises various elements known per se, such as an antenna  16 , a speaker  18 , a display  20 , a key pad  22  and a microphone  24 . Furthermore, the flip  14  comprises an internal sound-guiding channel (not shown), which also is known from the prior art and which extends longitudinally from a first end of the flip opposite the hinged end  26  to a second end, at which the microphone  24  is embedded inside the apparatus housing  12 . At the first end of the flip  14  a plurality of sound openings  30  are provided for the purpose of receiving spoken sound waves from the user, the sound waves then being guided through the internal part of the flip  14  and through the hinge mechanism  26  to the microphone  24 . 
     Furthermore, the mobile telephone  10  is provided with a magnetic sensor  32 , which is located inside the housing  12  beneath the keypad  22 , as illustrated in FIG. 1 by way of a dashed rectangle. The magnetic sensor  32  is connected, through conventional electrical conductors not illustrated in the drawing, to the logic circuitry inside the apparatus housing  12 . As will be apparent to a man skilled in the art the logic circuitry comprises e.g. a central processing unit (CPU), various memory circuits, controllers, etc. 
     The magnetic sensor  32  is of type, which is capable of detecting the presence of a magnetic field and converting this into an electric signal, which is provided as an output from the sensor  32  and which is related to the magnitude or field strength of the magnetic field. Hence, the magnetic sensor  32  will detect the presence of a magnetic field and convert the detected value into a corresponding electrical signal, which is supplied to the logic circuitry of the mobile telephone. The magnetic sensor  32  may be a hall element, a reed switch, a GMR sensor (i.e. a giant magnetoresistive sensor) or any other suitable element known from the field of magnetic detecting devices. 
     Contrary to some of the prior art mobile telephones described in previous sections, the inventive mobile telephone has no separate magnetic element for affecting the magnetic sensor  32 . Instead, the magnet already present in the speaker  18  is used as a source of magnetic field for the purpose of detecting the position of the flip  14  relative to the apparatus housing  12  by means of the magnetic sensor  32 . The magnetic field, or part of it, is conducted from the speaker  18  to the sensor  32  by a means or element  34 , which is located in the flip  14 , as shown in FIGS. 1-3. The means  34  is preferably a piece of metal plate attached to or embedded in the flip  14 , the metal plate hence being located in or in parallel to the plane of the flip  14 . When the flip  14  assumes an open position (cf. FIG.  2 ), the metal plate will have no influence on the magnetic sensor  32 . When, on the other hand, the flip  14  is closed as in FIG. 3, the metal plate will conduct a portion of the magnetic field from the speaker or buzzer  18  to the magnetic sensor  32 , the latter thereby being able to detect the magnetic field. Such an arrangement may also assist in-keeping the flip tight to the telephone by way of magnetic force. 
     The inventive principle is best shown is FIGS. 2 and 3, in which the mobile telephone  10  is illustrated in side views. In FIG. 2 the flip  14  assumes an open or folded out position, i.e. a position in which the mobile telephone  10  may be used for telephone conversation, while in FIG. 3 the flip  14  assumes an almost (for illustrating purposes) closed position, essentially corresponding to the position, to which the flip  14  is moved by a user after termination of the call. The apparatus housing  12 , the flip  14 , the antenna  16 , the speaker  18 , the display  20 , the key pad  22 , the hinge mechanism  26  and the magnetic sensor  32  are all identical in FIGS. 1-3, while a battery  34  is illustrated in FIGS. 2 and 3 but not in FIG.  1 . 
     When the flip  14  is in its open position according to FIG. 2, the magnetic distance d open     —     flip  between the magnetic sensor  32  and the speaker  18  is quite large, and since the strength of the magnetic field generated around the speaker  18  by the magnet thereof will decrease as a function of distance, the magnetic sensor  32  will only detect a magnetic field with a very weak field strength or even a zero field strength. As a consequence, the output signal provided by the magnetic sensor  32  to the logic circuitry of the mobile telephone will have a very low or even zero value. As seen in FIG. 3, on the other hand, when the flip  14  is in a closed or nearly closed position, the magnetic distance d closed     —     flip  WILL be considerably shorter than the distance d open     —     flip  in FIG. 2, since the metal plate  34  will conduct the magnetic field from the speaker  18  to the sensor  32 . Consequently, the field strength of the magnetic field generated by the magnet of the speaker  18  and detected by the magnetic sensor  32  will be much larger than the one of FIG.  2 . Accordingly, the output signal value supplied by the magnetic sensor  32  will exhibit a much larger value. 
     In this way the logic circuitry of the mobile telephone  10  is informed, by means of the magnetic sensor  32  and the metal plate  34 , of the position of the flip  14  relative to the apparatus housing  12 . This information may be used for e.g. enlightening the display  20  and/or the key pad  22 , when the user moves the flip  14  from its closed position according to FIG. 3 to its open or folded out position according to FIG.  2 . Furthermore, the logic circuitry may interpret the information of the flip  14  being closed or folded in by the user as an indication that an on-going call is to be terminated (i.e. an on-hook operation is to be performed). Furthermore, the logic circuitry may put itself in an idle or stand-by mode for conserving power. 
     As an alternative to the embodiment described above with reference to FIGS. 1-3, any electrodynamic means already present in the mobile telephone, such as a buzzer or a vibrator, may be used as a source of magnetic field, instead of the speaker magnet  18 . 
     The present invention has been described above with respect to preferred and alternative embodiments. However, embodiments other than the ones disclosed and described above are possible within the scope of the invention,