Abstract:
A hand-held electronic device for producing stereo effect sound in both a first and a second orientation of the device. The first and second directions are perpendicular to each other. The device comprises a pair of loudspeakers spaced from each other in two directions perpendicular to each other. One direction always lies in a horizontal plane irrespective of whether the device is in its first or second orientation.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a hand-held electronic device including a mobile telecommunications device such as a mobile phone or PDA, having loudspeakers mounted therein. The invention also relates to a method of controlling such a device. 
     BACKGROUND OF THE INVENTION 
     Recent developments in hand-held electronic devices such as mobile phones have resulted in improvements in the quality of sound reproduction, thereby enabling music to be played though such devices. Conventionally, it is common for the sound to be reproduced through headphones and an internally mounted loudspeaker is used only to produce general sounds such as ring-tones and other individual tones to signify key-presses. However, these devices are increasingly being provided with internal loudspeakers that can be used to project sounds/music directly from the device towards the listener in a hands-free format in addition to ring-tones and other more general sounds relating to the operation of the device. It will be appreciated that, if an internal loudspeaker is used to enable a user to listen to music, the quality of sound reproduction becomes an important consideration. 
     To maximise quality, it is desirable to be able to reproduce stereo effect sound to give the listener a greater 3-D or ‘spatial’ effect of the projected sound. However, producing stereo sound from a device as small as a mobile phone presents a number of problems. Firstly, two separate loudspeakers are required and, when the device is orientated in a position of use, the loudspeakers must be spaced horizontally from each other by a minimum distance so that sound is directed to either side of the listener to effectively reproduce a stereo effect. As mobile telecommunication devices are relatively small, obtaining the minimum horizontal spacing between the loudspeakers is difficult. However, if suitable digital processing is used, it is possible to spatially enhance the sound to expand the sound stage dramatically and produce a stereo effect. 
     The requirement for a minimum horizontal spacing between loudspeakers so as to direct sound towards either side of a listener leads to a problem when the device is intended for use in both an upright or ‘portrait’ position and also in a sideways or ‘landscape’ position. These two positions are illustrated by schematic front views of a prior art mobile device  10  comprising a mobile phone, shown in  FIGS. 1A and 1B . When the phone  10  is being used, it is intended that it will be placed so as to face the listener in one of these positions. The ‘landscape’ position may be preferable, for example, when the user is also viewing information displayed on the screen in a landscape orientation, at the same time as listening to sound as the screen may be rectangular, as opposed to square in shape and the information or picture displayed may be viewed more easily in a landscape orientation. It can be seen that the phone  10  is rotated through an angle of 90 degrees between these two positions. The mobile phone  10 , shown in the portrait position in  FIG. 1A , has a left loudspeaker  12  and a right loudspeaker  14 , separated from each other by a horizontal spacing H p  which is sufficient to enable spatial enhancement and reproduction of stereo sound. However, the mobile phone  10  is shown rotated clockwise by 90 degrees (see arrow A) into the landscape position in  FIG. 1B  and the loudspeaker  12  is now located directly above the loudspeaker  14 . This means that the horizontal spacing of the two loudspeakers  12 ,  14  in the landscape position H 1 , is reduced to zero, so that they provide no spatial effect, thereby rendering production of stereo sound impossible. An example of a device of this type is known from U.S. Pat. No. 6,760,447 (P. A. Nelson et al). 
     One solution to the problem referred to above is to provide a first pair of loudspeakers spaced from each other in the horizontal direction to provide stereo sound when the phone is in the portrait position, and a second pair of loudspeakers displaced from each other in a vertical direction perpendicular to the direction of displacement of the first pair of loudspeakers such that, when the phone is rotated into the landscape position, the second pair of loudspeakers are horizontally displaced from each other and are thereby able to produce stereo sound. 
     However, this prior art solution suffers from the drawback that two pairs of loudspeakers are required in the mobile phone, which in turn leads to increased production costs and an increase in the size of the device. An alternative solution could be to provide three loudspeakers in an ‘L’ formation to make up the two ‘pairs’ of loudspeakers in which one speaker would be used when the device is in the portrait position and also when the device is in the landscape position. However, this arrangement would also suffer the drawback that three loudspeakers would be required, again, leading to increased production costs and an increase in the size of the device. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a mobile device that substantially alleviates or overcomes the problems mentioned above. 
     Accordingly, the present invention provides a hand-held electronic device configured to reproduce stereo effect sound in both a first and a second orientation of the device perpendicular to each other, comprising a single pair of loudspeakers spaced from each other in two directions perpendicular to each other such that one of the directions always lies in a horizontal plane irrespective of whether the device is in its first or second orientation. 
     As there is a horizontal separation of the loudspeakers irrespective of whether the device is in the first or second orientation, sound is directed towards both sides of the listener and the spatial effect is maintained. 
     The mobile device is intended for use in a first upright or portrait position, and a second sideways or landscape position, the mobile device being rotated through 90 degrees between said first and second positions. The spacing between the loudspeakers in a first direction may be equal to the spacing between the loudspeakers in a second perpendicular direction. Alternatively, the spacing between the loudspeakers in a first direction may be less than or greater than the spacing between the loudspeakers in a second perpendicular direction. 
     The device may further include a controller configured to automatically change a digital processing algorithm used to produce the stereo effect sound to compensate for the difference in spacing between the loudspeakers in the first and second directions, when the device is rotated between the first and second positions. 
     The control unit may also be configured to swap the stereo sound signals fed to the loudspeakers when the orientation of the mobile device is changed between the first and second positions if, when changing the orientation of the mobile device between the first and second positions, the loudspeakers exchange places as the left-most speaker and right-most speaker respectively. 
     The hand-held electronic device may include a housing, the loudspeakers being disposed so as to face outwardly towards a user of the device from the housing. Alternatively, the housing may have a peripheral edge face, and at least one, or both of the loudspeakers may be disposed on the peripheral edge face of the housing. In one embodiment, the loudspeakers may be orientated so as to at least partially direct sound away from each other. 
     The present invention also provides a mobile telecommunications device for producing stereo effect sound in both a first and a second orientation of the device perpendicular to each other, comprising a single pair of loudspeakers spaced from each other in two directions perpendicular to each other such that one of the directions always lies in a horizontal plane irrespective of whether the device is in its first or second orientation. 
     The present invention also provides hand-held electronic device intended for use in two different orientations substantially at right angles to each other and configured to reproduce stereo effect sound in both said orientations, the device comprising a single pair of loudspeakers which, when the device is being used in either orientation, are spaced from each other in a direction which is substantially parallel to a fixed imaginary line of reference extending through the user&#39;s ears 
     According to another aspect of the invention, there is provided a method of controlling a hand-held electronic device configured to reproduce stereo effect sound in both a first and a second orientation of the device perpendicular to each other, comprising a single pair of loudspeakers spaced from each other in two directions perpendicular to each other such that one of the directions always lies in a horizontal plane irrespective of whether the device is in its first or second orientation, the method including the step of altering a digital processing algorithm to compensate for the difference in spacing between the loudspeakers when the device is rotated between the first and second orientations. 
     According to yet another aspect of the invention, there is provided a method of controlling a hand-held electronic device configured to reproduce stereo effect sound in both a first and a second orientation of the device perpendicular to each other, comprising a single pair of loudspeakers spaced from each other in two directions perpendicular to each other such that one of the directions always lies in a horizontal plane irrespective of whether the device is in its first or second orientation, the method including the step of swapping the stereo sound signals fed to the loudspeakers when the orientation of the mobile device is changed between the first and second orientations if, when changing the orientation of the mobile device between the first and second orientations, the loudspeakers exchange places as the left-most speaker and right-most speaker respectively. 
     Embodiments of the present invention will now be described, with reference to  FIGS. 2A-5  of the accompanying drawings, in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a schematic view of a prior art hand-held electronic device in an upright, portrait position; 
         FIG. 1B  is the prior art device of  FIG. 1A  in a sideways, landscape position; 
         FIG. 2A  is a schematic view of a hand-held electronic device according to a first embodiment of the invention in an upright, portrait position; 
         FIG. 2B  is the device of  FIG. 2A  in a sideways, landscape position; 
         FIG. 3A  is a schematic view of a hand-held electronic device according to a second embodiment of the invention in an upright, portrait position; 
         FIG. 3B  is the device of  FIG. 3A  in a sideways, landscape position; 
         FIG. 4A  is a schematic view of a hand-held electronic device according to a third embodiment of the invention in an upright, portrait position; 
         FIG. 4B  is the device of  FIG. 4A  in a sideways, landscape position; and 
         FIG. 5  is a schematic view of a hand-held electronic device according to a fourth embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to  FIGS. 2A and 2B , there is shown a first embodiment of a hand-held electronic device according to the present invention comprising a mobile telephone  100  having a housing  101  including a front face  106  and first and second loudspeakers  102 ,  104  mounted in the housing  101  so as to direct sound through apertures (not shown) in the front face  106 . The front face  106  includes a display screen  108 , the loudspeakers  102 ,  104  being disposed one either side of the display screen  108 . The phone  100  is shown in the portrait position in  FIG. 2A  and, as a user views the front face  106  of the phone  100 , the first loudspeaker  102  is on the left and the second loudspeaker  104  is on the right so as to direct sound towards the left and right hand sides of a listener, respectively. In this portrait position, the first and second loudspeakers  102 ,  104  are spaced from one another in the horizontal direction by a distance D 1  shown in  FIG. 2A . This spacing D 1  between the loudspeakers is sufficient to enable the reproduction of stereo effect sound when the phone  100  is in the portrait position. However, it can be seen from  FIGS. 2A and 2B  that the first and second loudspeakers  102 ,  104  are also diagonally disposed from one another which means that they are spaced from each other in a vertical direction D 2 . Although this vertical spacing D 2  has no discernable effect on the reproduction of stereo sound when the phone  100  is in the portrait position, when it is rotated by 90 degrees clockwise into the landscape position shown in  FIG. 2B , the spacing D 2  becomes a horizontal spacing of the first and second loudspeakers  102 ,  104  and so the phone  100  is still capable of reproducing stereo effect sound. 
     When stereo sound is produced, whether by conventional two-channel signals sent to two separate loudspeakers or by spatially digitally-processed signals sent to two separate loudspeakers, the electronic sound signals sent to each loudspeaker are not the same but are speaker-specific. When the phone  100  is rotated through 90 degrees clockwise (shown by arrow X) from the portrait position in  FIG. 2A  to the landscape position shown in  FIG. 2B , from the user&#39;s view point, the first loudspeaker  102  remains on the left-hand side and the second loudspeaker  104  remains on the right-hand side. Therefore, the signals transmitted to each loudspeaker  102 ,  104  by a signal processing unit do not need to be swapped over for the phone  100  to continue to reproduce stereo effect sound. 
     A second embodiment of the present invention is shown in  FIGS. 3A and 3B  comprising a mobile telephone  200  having a housing  201  and first and second loudspeakers  202 ,  204  mounted on a front face  206  of the housing  201 . The front face  206  includes a display screen  208  and the loudspeakers  202 ,  204  are disposed one either side of the display screen  208 . The phone  200  is shown in the portrait position in  FIG. 3A  and, as a user views the front face  206  of the phone  200 , the first loudspeaker  202  is on the left-hand side and the second loudspeaker  204  is on the right-hand side so as to direct sound towards either side of a listener facing the device. In this portrait position, the first and second loudspeakers  202 ,  204  are spaced from one another in the horizontal direction by a distance D 3  which is sufficient for the device to be able to produce stereo effect sound. As with the first embodiment  100  described above, the first and second loudspeakers  202 ,  204  are diagonally disposed from one another and so are spaced from each other in a vertical direction (shown as D 4  in  FIGS. 3A and 3B ) perpendicular to the horizontal direction D 3 . Therefore, when the phone  200  is rotated by 90 degrees clockwise (shown by arrow Y) to the landscape position shown in  FIG. 3B , the spacing D 4  becomes the horizontal spacing of the loudspeakers  202 ,  204 , thus ensuring that the phone is capable of reproducing stereo effect sound. 
     It can be seen that in this second embodiment, the distance D 4  between the first and second loudspeakers  202 ,  204  in the vertical direction when the phone  200  is in the portrait position, is greater than the distance D 3  in the horizontal direction. The electronic sound signals transmitted to each loudspeaker to produce stereo effect sound are calculated by a digital signal-processing audio algorithm in dependence upon a number of parameters, one of which is the spacing between the two loudspeakers. Therefore, because the horizontal spacing between the first and second loudspeakers  202 ,  204  differs between when the phone  201  is in the portrait position relative to the landscape position, the digital audio algorithm parameter must be changed to take account of the change in loudspeaker spacing so that the electronic signals transmitted to each loudspeaker  202 ,  204  are correct depending on whether the phone is in the portrait or landscape position. It has been found that a change in distance between the loudspeakers  202 ,  204  by a factor of up to 1.5 without changing the parameter of the digital audio algorithm to alter the electronic sound signals, has a relatively small detrimental effect on the quality of the stereo sound reproduction. For example, if D 3  was 4 cm, and D 4  was 6 cm, the effect on the sound quality would be negligible. However, if the factor is greater than 2, then a more serious deterioration in stereo sound reproduction is noticed and the digital algorithm parameter must be altered to take account of this when the orientation of the phone is changed. For example, if D 3  is 4 cm and D 4  is 8 cm, then the phone  200  would include a controller configured to detect the orientation of the phone  200  and to cause the digital audio algorithm to alter the electronic sound signals transmitted to the loudspeakers  202 ,  204  to take account of the difference in horizontal distance between the loudspeakers  202 ,  204  in the portrait position and the landscape position. As mentioned above, a user may wish to view information displayed on the screen  208  in a landscape orientation, in which case, the phone would have a control function to allow the user to manually select the desired screen orientation. In this case, the controller would not need a means to detect which orientation the phone is to be used in, as instead, the information could be taken from the manually operated control function used to display information on the screen in the correct orientation and, from this, the controller would select the correct parameter for the digital audio algorithm appropriate to the horizontal spacing of the loudspeakers. 
     A third embodiment of the present invention is shown in  FIGS. 4A and 4B  comprising a mobile telephone  300  having a housing  301  and first and second loudspeakers  302 ,  304  mounted on a front face  306  of the housing  301 . The front face  306  includes a display screen  308  and the loudspeakers  302 ,  304  are disposed one either side of the display screen  308 . The phone  300  is shown in the portrait position in  FIG. 4A  and, as a user views the front face  306  of the phone  300 , the first loudspeaker  302  is on the left-hand side and the second loudspeaker  304  is on the right-hand side. As with the first embodiment shown in  FIGS. 2A and 2B , the first and second loudspeakers  302 ,  304  are spaced from each other in the horizontal direction by a first distance D 5 , and are spaced from each other in the vertical direction by a second distance D 6  (see  FIG. 4A ). In this embodiment, the position of the loudspeakers  302 ,  304  is such that in the portrait position, the first loudspeaker  302  is on the left and the second loudspeaker  304  is on the right. However, when the phone  300  is rotated by 90 degrees clockwise into the landscape position as shown by arrow and  FIG. 4B , the first loudspeaker  302  becomes the right loudspeaker and the second loudspeaker  304  becomes the left loudspeaker. Likewise, this loudspeaker reversal would also occur if the first and second embodiments of the invention described above and illustrated in  FIGS. 2A ,  2 B,  3 A, and  3 B were rotated anti-clockwise into the landscape position. As mentioned above, to reproduce stereo effect sound, the electronic signals sent to each loudspeaker  302 ,  304  are not identical, but are specific to whether the loudspeaker is the right or the left loudspeaker. Therefore, to allow for the swapping of sides of the loudspeakers  302 ,  304  in moving between the portrait and the landscape positions, the mobile phone  300  includes a controller (not shown) to automatically detect which position the phone  300  is in and transmit the appropriate electronic signals to the correct left/right loudspeaker accordingly. 
     It is envisaged within the scope of the invention that a further, unillustrated embodiment may include controller functions of the second embodiment in  FIGS. 3A and 3B  and also of the third embodiment in  FIGS. 4A and 4B . This would allow the device to be capable of detecting the horizontal spacing between the loudspeakers in the portrait and landscape positions and to alter the electronic stereo sound signals transmitted to each loudspeaker accordingly if the horizontal spacing changes, and also to detect which loudspeaker was the left loudspeaker and which was the right loudspeaker for whichever orientation the device was positioned in to ensure that each loudspeaker receives the correct electronic stereo sound signal to reproduce the desired stereo effect sound. 
     The various embodiments described above have all been shown with the loudspeakers positioned on one single face of the device. However, further embodiment  400 , illustrated in  FIG. 5 , shows how the loudspeakers could be arranged in an alternative configuration. This fourth embodiment  400  comprises a housing  401  having a front face  406  with a display screen  408 , a rear face  410  and a peripheral edge face  412 . First and second loudspeakers  402 ,  404  are disposed at diagonally opposed corners of the device  400 , with the first loudspeaker  402  extending over one corner of the front face  406  and the peripheral edge face  412  at the top and one side of the device, and the second loudspeaker  404  extending over the diagonally opposite corner of the front face  406  and the peripheral edge face  412  at the bottom and opposite side so that sound is directed towards the user of the device from both the front and side of the device. The device would operate as described above with reference to the first to third embodiments of the invention, except that the sound projection from the first and second loudspeakers  402 ,  404  would be improved due to the outward projection of sound that could be achieved over flat face-mounted speakers. 
     It is also envisaged that the speakers could be located so as to face wholly outwardly from either side of the housing rather that having at least a portion facing towards the user. In such a configuration, the design tuning of the device would be critical to maximise performance. 
     Many modifications and variations of the invention falling within the terms of the appended claims will be apparent to those skilled in the art and the foregoing description should be regarded as a description of the preferred embodiments only.