Abstract:
The present invention is directed towards a portable electronic equipment ( 10 ) comprising a speaker ( 16 ) and a receiver ( 18 ), wherein the receiver ( 18 ) is damped while the speaker ( 16 ) is active to provide good sound reproduction.

Description:
TECHNICAL FIELD OF THE INVENTION 
   The present invention relates to the field of portable electronic equipment, in particular to high quality sound reproduction in such a device. 
   DESCRIPTION OF RELATED ART 
   A conventional portable electronic equipment such as a cellular phone typically comprises elements such as a housing, a display, operation buttons, a speaker, and a receiver for outputting received sound and a microphone for converting voice from a user to a sound signal to be transmitted. The volume available, for instance, put restrictions on the back volume available for the speaker and the receiver. Therefore they may have to share the same back volume. 
   Herein, the term “receiver” is referred to as an element that transduces electric signals into sound. Herein, a “speaker” is referred to an element typically employed to provide a ringer signal. 
   However, if the receiver and the speaker share the same back volume there will be a number of problems. One problem is that the receiver will act as a leak when the loudspeaker is active, with loss in the low frequencies as a result, resulting in lower quality sound reproduction. 
   Yet another problem is that there is a risk for loud ringer levels in the receiver outlet. 
   Thus, there is a need for a portable electronic equipment which provides high quality sound reproduction having speaker and receiver sharing the same back volume. 
   SUMMARY OF THE INVENTION 
   Aspects of the present invention are therefore directed towards providing high quality sound reproduction in a portable electronic equipment having a speaker and a receiver sharing the same back volume. 
   One aspect of the present invention is thus directed towards providing a portable electronic equipment with simulated closed box behavior with shared back volume. 
   Herein the term “simulated closed box behavior” is referred to as an ideal behavior without leaking problems. 
   According to a first aspect of the present invention, a portable electronic equipment is provided comprising: 
   a speaker for sound reproduction, and a receiver for sound reproduction, which speaker and receiver share a back volume, characterised in that said portable electronic equipment comprises a control/damping unit arranged to damp the receiver while the speaker is active. 
   A second aspect of the present invention includes the features of the first aspect, wherein said control/damping unit comprises a control unit that controls switching between receiver mode and speaker mode. 
   A third aspect of the present invention includes the features of the second aspect, wherein said control unit is arranged to control voltage or current over the receiver such that it avoid the latter to operate as a leak. 
   A fourth aspect of the present invention includes the aspect of any one of the previous aspects, wherein the equipment is a cellular phone, a smart phone or a communicator. 
   A fifth aspect of the present invention is directed towards a method for sound reproduction in a portable electronic equipment comprising a speaker and a receiver for sound reproduction, comprising the steps of:
         providing sound reproduction by means of a speaker and a receiver sharing a back volume,   damping the receiver while the speaker is active.       

   A sixth aspect of the present invention includes the features of the fifth aspect, wherein voltage or current over the receiver is controlled such that it avoids the latter to operate as a leak. 
   A seventh aspect of the present invention includes the features of the fifth or the sixth aspect, wherein switching between speaker mode and sound receiver mode is controlled to provide damping the receiver while the speaker is active. 
   The present invention has many advantages, one being that it prevents loss in the low frequency response of the speaker. Another advantage of the present invention is that loud ringer levels in the receiver outlet are avoided. 
   It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps or components, but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will now be described in more detail in relation to the enclosed drawings, in which: 
       FIG. 1  is a schematic front view (not to scale) illustrating a portable electronic equipment according to a first embodiment of the present invention, 
       FIG. 2  is side view of the portable electronic equipment illustrated in  FIG. 1 , 
       FIG. 3  is a side view and a block diagram showing the brief internal composition of the first embodiment of the invention, and 
       FIG. 4  is a flow chart of the method according to an embodiment of the invention. 
   

   DETAILED DESCRIPTION OF EMBODIMENTS 
   Referring now to the drawings, a description will be given in detail of embodiments in accordance with the present invention. 
   A portable electronic equipment  10  according to an embodiment of the invention is shown in  FIGS. 1 ,  2  and  3 . In a first preferred embodiment, the portable electronic equipment  10  is a cellular phone having an antenna (not shown), a display  12  and operating buttons  14 . As shown in  FIG. 2 , a first signal-vibration transducer for implementing a speaker  16  provided with a back-volume  17  is located to the left of the cellular phone, and a second signal-vibration transducer for implementing a receiver  18  is located to the right nearby the first one sharing the same back-volume  17 . Preferably, the first and the second signal-vibration transducers (speaker and receiver) are provided as separate transducers, which will be explained in more detail below. 
   According to the various embodiments the invention, including this first one, the speaker  16  and the receiver  18  shares the same back-volume  17 . Some of the reasons for this is that because of size-constraints this is a preferred solution. 
   The cellular phone  10  receives signals transmitted from radio base stations by its antenna (not shown). The signals received are transmitted to a radio unit (not shown) comprising or connected to conventional units for modulation/demodulation and sound processing. 
   To the radio unit, a ringer for providing a ringing tone is typically connected. The ringer can provide a ringing tone by means of the speaker  16 , such that the user can be informed of an incoming call. 
     FIG. 3  is a view illustrating the brief internal composition for implementing the invention. 
   The speaker  16  is connected to a first amplifier  25  and a first sound signal source  26 . The receiver  18  is connected to a second sound signal source  27 , which is connected to a second amplifier  31 . When the speaker  16  is active, a control/damping unit  33  ensures that the diaphragm (known per se) of the receiver  18  is controlled to a fix position, preferably the position at rest. This will result in a decrease of the acoustic leakage through the receiver  18 . When the receiver  18  is active, the control/damping unit  33  is inactive and the signal from the second sound signal source  27  is amplified and played on the receiver  18 . 
   Preferably, the control/damping unit  33  is arranged to actively damp the receiver  18  while the speaker  16  is active, step  101  in  FIG. 4 . Preferably, this is achieved by using a fast simple control algorithm for controlling the current or voltage over the receiver  18  such that movement of the membrane is removed or at least reduced. 
   Preferably, the control/damping unit  33  comprises a control unit that controls switching between speaker mode and receiver mode. When a user listens to speech from another party, the control unit  33  controls current or voltage over the receiver  18  to avoid the latter to operate as a leak. Preferably, the second sound amplifier  31  of the receiver  18  is damped such that high quality sound reproduction can be realised by the speaker  16  typically wide-range and high volume sound reproduction also including low frequencies without impairing usability of the cellular phone. 
   Preferably, the control/damping unit is implemented as a software only solution, for instance comprising a processing unit and corresponding memory. Also, already existing software could be upgraded to provide the control/damping unit in the form of a simple control algorithm for controlling the current or voltage over the receiver such that movement of the membrane is removed or at least reduced due to leaking problems. 
   This is a great advantage with the present invention, since this prevents loss in low frequency range of the speaker and also reduces the risk for loud ringer levels in the receiver output. 
   It should be realised that cellular phone is just one type of device in which the invention can be implemented. It can just as well be provided in other types of portable electronic devices such as a lap top computer, a palm top computer, an electronic organizer, a smart-phone, a communicator, a calculator or a gaming machine. 
   There are more ways in which the invention can be varied. Therefore the invention is only to be limited by the accompanying claims.