Patent Document

RELATED APPLICATIONS  
       [0001]     This application claims priority under 35 U.S.C. § 119 based on U.S. Provisional Application Ser. No. 60/740,655, filed Nov. 30, 2005, the disclosure of which is incorporated herein by reference. 
     
    
     TECHNICAL FIELD OF THE INVENTION  
       [0002]     The present invention relates to an electro-acoustic communications unit and a portable electronic device including an electro-acoustic communications unit.  
       DESCRIPTION OF RELATED ART  
       [0003]     A portable electronic device, for instance of the cellular phone type, is normally provided with electro-acoustic elements such as speakers and microphones in order to produce and receive sound.  
         [0004]     For a speaker, there is a speaker box or back volume behind the membrane of the speaker. For a cellular phone, this volume is normally decided by air gaps provided between different components and elements of the phone. This means that the back volume cannot readily be designed for the best audio performance as in, for instance, hifi equipment.  
         [0005]     In the field of hifi equipment, there have been investigations concerning the use of helium instead of air in such a back volume. The reason that this is done is to avoid resonance caused by the speaker box.  
         [0006]     However, it may for some applications be desirable to have a speaker, where the membrane can provide larger strokes/excursions for proving higher sound volumes, especially when playing music. For some applications it may be desirable to provide a more stiff suspension of the speaker element in the phone. This may be desirable if distortion problems are to be avoided as the loudspeaker membrane and suspension would be better balanced, thus lowering the chance for rocking mode distortion phenomenon.  
         [0007]     There is thus a need for providing an improved electro-acoustic communications unit that solves at least some of the above mentioned problems.  
       SUMMARY OF THE INVENTION  
       [0008]     The invention is thus directed towards providing an electro-acoustic communications unit which can be used for providing larger strokes or a more stiff suspension of acoustic signal emitting elements of the electro-acoustic communications unit.  
         [0009]     This may be achieved through using an acoustic driver, which when operated emits acoustic waves in two directions, to which a hermetically sealed container comprising a gas is attached, where the gas transports acoustic waves generated by the acoustic driver.  
         [0010]     Aspects of the invention provide an improved electro-acoustic communications unit, and especially one which can be used for providing larger strokes or a more stiff suspension of an acoustic signal emitting element of the unit.  
         [0011]     According to a first aspect of the invention, an electro-acoustic communications unit for mounting in a cellular phone, comprises an acoustic driver, which when operated emits acoustic waves in two directions, and a hermetically sealed container attached to the acoustic driver and comprising a gas other than air, which gas transports acoustic waves generated by the acoustic driver.  
         [0012]     A second aspect of the invention is directed towards an electro-acoustic communications unit including the features of the first aspect, wherein the hermetically sealed container has at least one flexible wall, the shape of which will be determined at least partly by elements in the interior of a portable electronic device where the unit is to be mounted.  
         [0013]     A third aspect of the invention is directed towards the electro-acoustic communications unit including the features of the first aspect, wherein the acoustic driver comprises an acoustic signal generating element that is attached to the container.  
         [0014]     A fourth aspect of the invention is directed towards the electro-acoustic communications unit including the features of the first aspect, wherein a part of the container is an acoustic signal generating element of the acoustic driver.  
         [0015]     A fifth aspect of the invention is directed towards the electro-acoustic communications unit including the features of the first aspect, further comprising an absorbent covering the entire hermetically sealed container, except for parts connected to or being part of the acoustic driver.  
         [0016]     A sixth aspect of the invention is directed towards the electro-acoustic communications unit including the features of the first aspect, wherein the gas is lighter than air.  
         [0017]     A seventh aspect of the invention is directed towards the electro-acoustic communications unit including the features of the sixth aspect, wherein the gas is helium.  
         [0018]     An eight aspect of the invention is directed towards the electro-acoustic communications unit including the features of the first aspect, wherein the gas is heavier than air.  
         [0019]     A ninth aspect of the invention is directed towards the electro-acoustic communications unit including the features of the first aspect, wherein the container is made of rubber.  
         [0020]     Other aspects of the invention provide a portable electronic device that includes an improved electro-acoustic communications unit, and especially one which can be used for providing larger strokes or a more stiff suspension of an acoustic signal emitting element of the unit.  
         [0021]     According to a tenth aspect of the invention, a portable electronic device that comprises an electro-acoustic communications unit is provided. The portable electronic device comprises an acoustic driver, which when operated emits acoustic waves in two directions, and a hermetically sealed container attached to the acoustic driver and comprising a gas other than air, where the gas transports acoustic waves generated by the acoustic driver.  
         [0022]     An eleventh aspect of the invention is directed towards the portable communication device including the features of the tenth aspect, wherein the hermetically sealed container has at least one flexible wall, the shape of which is determined at least partly by elements in the interior of the portable electronic device.  
         [0023]     A twelfth aspect of the invention is directed towards the portable communication device including the features of the tenth aspect, wherein the acoustic driver comprises an acoustic signal generating element that is attached to the container.  
         [0024]     A thirteenth aspect of the invention is directed towards the portable communication device including the features of the tenth aspect, wherein a part of the container is an acoustic signal generating element of the acoustic driver.  
         [0025]     A fourteenth aspect of the invention is directed towards the portable communication device including the features of the tenth aspect, further comprising an absorbent covering the entire hermetically sealed container, except for parts connected to or being part of the acoustic driver.  
         [0026]     A fifteenth aspect of the invention is directed towards the portable communication device including the features of the fourteenth aspect, wherein the gas is lighter than air.  
         [0027]     A sixteenth aspect of the invention is directed towards the portable communication device including the features of the fifteenth aspect, wherein the gas is helium.  
         [0028]     A seventeenth aspect of the invention is directed towards the portable communication device including the features of the tenth aspect, wherein the gas is heavier than air.  
         [0029]     An eighteenth aspect of the invention is directed towards the portable communication device including the features of the tenth aspect, wherein the container is made of rubber.  
         [0030]     A nineteenth aspect of the invention is directed towards the portable communication device including the features of the tenth aspect, wherein the device is a portable communication device.  
         [0031]     A twentieth aspect of the invention is directed towards the portable communication device including the features of the nineteenth aspect, wherein the device is a cellular phone.  
         [0032]     The present invention has a number of advantages. For example, aspects of the invention enable the provision of larger strokes or a more stiff suspension of acoustic signal emitting elements of the electro-acoustic communications unit. The invention according to the second and eleventh aspects furthermore allows the unit to use the available mounting volume provided in a portable electronic device in an effective way. The absorbent according to the fifth and fourteenth aspects furthermore allows the volume occupied by the unit to be better defined and thus the strokes of the acoustic driver may be better controlled as compared to using no absorbent.  
         [0033]     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  
       [0034]     The present invention will be more clearly understood from the following description of the present invention, read in conjunction with the attached drawings, where  
         [0035]      FIG. 1  shows a front-view of a portable electronic device according to the present invention,  
         [0036]      FIG. 2  shows a side-view of the phone in  FIG. 1  and comprising an electro-acoustic communications unit according to a first embodiment of the present invention,  
         [0037]      FIG. 3  schematically shows the electro-acoustic communications unit according to the first embodiment of the present invention,  
         [0038]      FIG. 4  schematically shows the electro-acoustic communications unit according to a second embodiment of the present invention, and  
         [0039]      FIG. 5  schematically shows the electro-acoustic communications unit according to a third embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0040]     The present invention relates to an electro-acoustic communications unit and a portable electronic device including such an electro-acoustic communications unit.  
         [0041]      FIG. 1  shows a front view of a portable electronic device in the form of a cellular phone  10 . The phone  10  has a casing  12  where a keypad  14 , a display  16  and a sound opening  18  is provided. Beneath the opening  18  within the casing  12 , an electro-acoustic communications unit according to the invention is provided. The portable electronic device  10  is, according to a preferred variation of the present invention, a cellular phone. It should however be realized that the present invention is not limited to cellular phones, but may be provided in other portable communication devices and portable electronic devices like lap top computers, palm top computers, organizers, cordless phones or gaming machines.  
         [0042]      FIG. 2  shows a cross-sectional side view of the phone of  FIG. 1 . It should here be noted that many elements of the phone  10  have been omitted in order to concentrate on the teachings of the present invention.  
         [0043]     In  FIG. 2  there is shown the keypad  14  on the casing  12  of the phone  10  and the display  16  just underneath it (shown as a dashed box). Above the display  16 , the sound opening  18  is provided. Just underneath this opening  18 , there is provided an electro-acoustic communications unit  20  according to the invention. This unit is referred to herein as a speakerbox package. There is here also a circuit board  21  provided underneath the electro-acoustic communications unit  20 , the keypad  14  and the display  16 , but within the casing  12 .  
         [0044]     The electro-acoustic communications unit according to the first embodiment of the present invention is schematically shown in  FIG. 3 . The unit  20  is provided with an acoustic driver in the form of an ordinary electromagnetic loudspeaker  22 , the back side of which is directly attached to a hermetically sealed container  24  having an elastic, deformable and flexible wall. The container may therefore be stretched and deformed. The speaker  22  has an acoustic signal generating element in the form of a membrane  23  (shown as a dashed ellipse). The container is made of an elastic material, such as rubber, and is non-permeable for gas. One side of the membrane  23  of the speaker  22  is here directly attached to this rubber container  24 , while the other side faces the sound opening of the casing. For illustrative purposes, an enclosing volume V is indicated with a dashed box. The enclosing volume V is in reality made up of the elements of the phone that surround the electro-acoustic communications unit  20 , like parts of the casing, the circuit board, components on the circuit board, the display, an antenna, an antenna connector, etc.  
         [0045]     The container  24  furthermore contains a gas P 1  which is different than the gas P 2  surrounding the container. The surrounding gas P 2  is here air. Because of the non-permeable nature of the container wall, the gas P 1  cannot escape from the container  24 .  
         [0046]     When the electro-acoustic communications unit  20  according to this first embodiment is mounted into the phone, the elastic wall adapts to the volume V. The shape of the wall is thus determined by this volume V. The container  24  thus adapts in shape to the surrounding area where it is mounted in order to as effectively as possible provide a back volume for the speaker  22 .  
         [0047]     The gas P 1  of the speaker may be lighter than air, preferably helium. When the speaker  22  is operated, the membrane of the speaker emits sound into the air from the front side. However, the back side emits sound into the the helium filled back volume defined by the container  24 . This gas, that is “softer” and less dense than air, gives a good balance to the speaker and also ensures larger strokes for the membrane  23 , and thus the possibility of providing a higher sound volume.  
         [0048]     The gas P 1  may be also be heavier than air P 2 . In this case, the gas P 1  provides a stiffer suspension of the speaker element, which lowers distortion that occurs at the resonance frequency of the speaker  22 . It also balances the speaker better so that rocking mode distortion phenomena are less likely to occur.  
         [0049]     In  FIG. 4 , there is schematically shown a second embodiment of the electro-acoustic communications unit  20  according to the invention. Here the container  24  is connected to the front side of the speaker  22 . In this embodiment the speaker is supposed to have its back side facing outwards towards the casing and its front side facing inwards into the phone. As is well known within the field, a speaker operates equally well on both sides. In this embodiment the container wall is furthermore also a part of the membrane of the speaker, which means that a part of the container wall actually is a membrane of the speaker. This has the advantage of allowing a simpler manufacturing of the electro-acoustic communications unit  20  because the speaker membrane  23  and the container  24  may be provided in one piece of the same material.  
         [0050]      FIG. 5  schematically shows a third embodiment of the electro-acoustic communications unit  20  according to the present invention. In this embodiment, which has the same relationship between speaker  22  and container  24  as the first embodiment, there is furthermore provided an absorbent  26 , which may be a porous fiber material, such as, for example, Rockwool, which acoustically acts as a spring. The material  26  may cover the entire container  24  except for the parts connected to the speaker  22 . This material holds the container  24  in the place that has been reserved for it. The absorbent  26  also allows the back volume to be better defined and thus the strokes of the speaker  22  may be controlled better than without it.  
         [0051]     It is emphasized that this invention can be varied in many more ways, than the ones described above. It is for instance possible to equip the container with more walls and also provide these walls as rigid walls. The container need not be made of rubber but can be made of a suitable plastic material instead. Hence the present invention is only to be limited by the following claims.

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