Patent Publication Number: US-2019200116-A1

Title: Loudspeaker, mobile device and method of manufacturing a loudspeaker

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention relates to a loudspeaker and to a method of manufacturing a loudspeaker. The invention also relates to a mobile device, such as a mobile phone, comprising a loudspeaker. 
     Related Prior Art 
     European patent No. 2 424 270 B1 discloses a loudspeaker which comprises an enclosure and a dynamic driver mounted in the enclosure. The enclosure is filled with a zeolite material. Filling the enclosure with the zeolite material results in in an apparent virtual enlargement of the volume defined by the enclosure, i.e. results in increasing the effective volume of the enclosure. The zeolite material comprises grains having an average grain size in a range between 0.2 and 0.9 mm and having a plurality of zeolite particles adhered together by means of a binder. The zeolite particles comprise pores and have a silicon to aluminum mass ration of at least 200. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a loudspeaker comprised of an enclosure and a dynamic driver mounted in the enclosure, which loudspeaker can be manufactured more easily. 
     The object of the invention is achieved by means of a loudspeaker, comprising an enclosure; at least one dynamic driver mounted in the enclosure; and at least one porous monolithic block mounted within the enclosure. 
     A further aspect of the invention relates to a method of manufacturing the loudspeaker according to the invention, comprising the steps of:
         providing a plurality of particles;   producing the at least one porous monolithic block utilizing the plurality of particles; and   mounting the porous monolithic block into the enclosure.       

     Another aspect of the invention relates to a mobile device comprising a loudspeaker according to the invention. The mobile device is, for instance, a mobile telephone. 
     Yet another aspect of the invention relates to a method of producing the mobile device according to the invention, comprising the steps of:
         providing a plurality of particles;   producing the at least one porous monolithic block; and   mounting the porous monolithic block into the enclosure.       

     The loudspeaker comprises the enclosure. The enclosure is preferably a sealed enclosure. Sealed loudspeaker enclosures are also referred to as closed enclosures. 
     The loudspeaker comprises at least one dynamic driver. Dynamic drivers per se are known to the skilled person. Dynamic drivers usually comprise a magnet system, a membrane movably mounted with respect to the magnet system, and a voice coil attached to the membrane. The magnet system comprises a magnet and the voice coil is operatively coupled with the magnet. When applying an electric signal to the voice coil, for instance, generated by an amplifier, then the membrane moves in response to the electric signal. The electric signal is, for instance, an electric voltage. 
     The enclosure provides a volume, specifically a back volume for the dynamic driver. 
     The loudspeaker further comprises the at least one porous monolithic block which is mounted within the enclosure. Thus, the at least one monolithic block is placed within the back volume for the dynamic driver. 
     Particularly, the porous monolithic block comprises a plurality of first pores. Preferably, the first pores have a size or diameter between 0.7 μm and 30 μm. Inter alia due to the first pores, the effective volume of the loudspeaker, i.e. the effective back volume for the dynamic driver is greater than the back volume for the dynamic driver without the at least one porous monolithic block, resulting in a potential increased sound quality of the entire loudspeaker. Particularly, due to the at least one porous monolithic block, a resonance frequency of the entire loudspeaker may be reduced compared to the resonance frequency of the entire loudspeaker without the at least one porous monolithic block. Therefore, it may be possible to reduce the overall volume of the loudspeaker or its enclosure, respectively, allowing to manufacture a relatively small loudspeaker especially having an improved or at least an acceptable sound quality when, for instance, using it for a mobile device, such as a mobile phone. 
     The porous monolithic block may be made from any suitable material. Preferably, the porous monolithic block comprises a zeolite material. The porous monolithic block may even consist of a zeolite material. 
     There may only a single porous monolithic block be mounted within the enclosure. 
     The enclosure may comprise a plurality of sub-enclosures acoustically coupled to each other and, thus, forming the enclosure. The at least one porous monolithic block may be mounted within at least one of the sub-enclosures. For instance, in one or at least in some of the sub-enclosures may be mounted each a single porous monolithic block. It may also be possible that one of the sub-enclosures is associated with the dynamic driver, i.e. that the dynamic driver is mounted in one of the sub-enclosures. Then, the sub-enclosure associated with the dynamic driver may be empty, while the at least one porous monolithic block is mounted within at least one of the remaining sub-enclosures. 
     The at least one porous monolithic block may be adapted to the shape of the enclosure or to the shape of the relevant at least one sub-enclosure, respectively. Particularly, the enclosure may have a contour and the at least one porous monolithic block may be mounted into the enclosure in a form-fit manner corresponding to the contour of the enclosure. If the enclosure comprises the plurality of sub-enclosures, then the at least one porous monolithic block may be mounted into the relevant sub-enclosure in a form-fit manner corresponding to the contour of that sub-enclosure. 
     The at least one porous monolithic block may be produced using a freezing casting method using a plurality of particles. Alternatively, the at least one porous monolithic block may be produced by a freezing foaming method using the plurality of particles, a sintering method using the plurality of particles, a ceramic foaming method using the plurality of particles, or a self-curing binding technique using the plurality of particles. The particles are preferably porous particles having second pores. Preferably, the size of the second pores may differ from the size of the first pores. The second pores may have a size or diameter of less than 1 nm. When utilizing the porous particles for producing the porous monolithic block, then the porous monolithic block may comprise the first pores and at least some of the second pores of the porous particles. 
     For the aforementioned methods, an appropriate mold may be used. The contour of the mold may correspond to the contour of the enclosure or to the relevant sub-enclosure, respectively, in order to produce a porous monolithic block having a shape adapted to the shape of the enclosure or the relevant sub-enclosure, or whose contour matches the contour of the enclosure or the relevant sub-enclosure for the form-fit mounting. 
     For instance, if the at least one porous monolithic block is made utilizing the freezing casting method, then the mold may at least partly be made from PTFE (Polytetrafluorethylen). 
     For instance, if the porous monolithic block is made utilizing the freezing foaming method, then the mold may at least partly be made from silicon rubber. 
     The particles or the porous particles may be any suitable organic or inorganic particles or porous particles, respectively. Preferably, the particles may be zeolite particles. The porous particles may be porous zeolite particles. 
     Especially, the porous particles form a zeolite powder. In particular, the zeolite particles are similar or equal those published by European application for patent No. 2 424 270 which is entirely incorporated by reference. The zeolite particles may have diameters of 10 μm in diameter or smaller. 
     Contrary to the method disclosed by European application for patent No. 2 424 270 the particles are not used for producing a plurality of grains, however, according to embodiments of the invention, to produce the at least one porous monolithic block. 
     The at least one porous monolithic block may be produced by providing an appropriate binder and a mold whose contour corresponds to the contour of the enclosure or the relevant sub-enclosure. Then, the binder and the plurality of particles may be mixed and this mixture may be filled into the mold. Then, the mold filled with the mixture of the plurality of particles and the binder is frozen in order to produce the at least one porous monolithic block. Then, the mold is removed from the porous monolithic block. This method basically describes a freezing casting method. 
     The at least one porous monolithic block may be produced by providing an appropriate binder and a mold whose contour corresponds to the contour of the enclosure or the relevant sub-enclosure. Then, the binder and the plurality of particles may be mixed and this mixture may be filled into the mold. Then, the ambient pressure around the mold filled with the mixture of the plurality of particles and the binder is reduced in order to produce the porous monolithic block. Then, the mold is removed from the porous monolithic block. This method basically describes a freezing foaming method. 
     The at least one porous monolithic block may be produced by providing an appropriate binder and a mold whose contour corresponds to the contour of the enclosure or the relevant sub-enclosure. Then, the binder and the plurality of particles may be mixed and this mixture may be filled into the mold. Then, the mold filled with the mixture of the plurality of particles and the binder is heated in order to produce the relevant porous monolithic block. During the heating, the binder burns at least partially. For example, two different kinds of binders may be used. One type of binder may be a temporary binder which burns completely or almost completely during the heating creating the first pores. Another type of binder may not burn during the heating. Then, the mold is removed from the porous monolithic block. This method basically describes a sintering method. Alternatively, the foaming of the plurality of particles can also be achieved by a ceramic foaming method. 
     The at least one porous monolithic block may be produced by providing a protein foam as a structuring agent, an appropriate binder and a mold whose contour corresponds to the contour of the enclosure or the relevant sub-enclosure. Then, the protein foam, the binder and the plurality of particles may be mixed and this mixture may be filled into the mold. Then, one has to wait until the mixture filled into the mold self-cures in order to produce the porous monolithic block. Then, the mold is removed from the porous monolithic block. This method basically describes a self-curing binding method. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top view of a mobile phone; 
         FIG. 2  is a top view of a loudspeaker comprising monolithic blocks, a dynamic driver and an enclosure which is shown open; 
         FIG. 3  is a top view of the opened enclosure; 
         FIG. 4  are the monolithic blocks; 
         FIG. 5  is a plurality of particles; 
         FIG. 6  is a mold; and 
         FIG. 7  is a flow chart. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows a mobile phone  1  as an example of a mobile device. The mobile phone  1  may comprise a microphone, a wireless sender-receiver unit, an amplifier and a central processing unit connected to the wireless sender-receiver unit and to the amplifier. 
     The mobile device  1  comprises a loudspeaker  21  which is shown in  FIG. 2 . The amplifier of the mobile phone  1  may be connected to the loudspeaker  21 . 
     The loudspeaker  21  comprises at least one dynamic driver  22 . Dynamic drivers per se are known to the skilled person. Dynamic drivers usually comprise a magnet system, a membrane movably mounted with respect to the magnet system, and a voice coil attached to the membrane. The magnet system comprises a magnet and the voice coil is operatively coupled with the magnet. When applying an electric signal to the voice coil, for instance, generated by the amplifier, then the membrane moves in response to the electric signal. 
     The loudspeaker  21  comprises an enclosure  23  and at least one porous monolithic block mounted within the enclosure  23 . In particular, the loudspeaker  21  comprises a first porous monolithic block  24   a  and a second porous monolithic block  24   b.    
       FIG. 2  shows in particular a top view of the of the loudspeaker  21  with its enclosure  23  opened.  FIG. 3  shows a top view of the opened enclosure  23  and  FIG. 4  shows the porous monolithic blocks  24   a ,  24   b.    
     In the present embodiment, the enclosure  23  comprises a plurality of sub-enclosures, namely a first sub-enclosure  23   a , a second sub-enclosure  23   b , and a third sub-enclosure  23   c . The sub-enclosures  23   a ,  23   b ,  23   c  are acoustically coupled to each other and form, as a result, the single enclosure  23  for the dynamic driver  22 . 
     In the present embodiment, the enclosure  23  is a sealed enclosure. Sealed enclosures are also known as closed enclosures. 
     The dynamic driver  22  is mounted in the third sub-enclosure  23   c . In particular, the third sub-enclosure  23   c  comprises an aperture  25  in which the dynamic driver  22  is mounted. 
     The porous monolithic blocks  24   a ,  24   b  are mounted within the enclosure  23 . In the present embodiment, the first porous monolithic block  24   a  is mounted within the first sub-enclosure  23   a , and the second porous monolithic block  24   b  is mounted within the second sub-enclosure  23   b.    
     The first and second sub-enclosures  23   a ,  23   b  may be identical or, as shown in the figures, may differ from each other. 
     The porous monolithic blocks  24   a ,  24   b  each comprise first pores  27 . Particularly, the first pores  27  have a diameter between 0.7 μm to 30 μm. 
     Preferably, the porous monolithic blocks  23   a ,  23   b  comprise each a zeolite material. Due to the porous monolithic blocks  24   a ,  24   b , the effective volume of the enclosure  23  is greater than the volume of the enclosure  23  without the porous monolithic blocks  24   a ,  24   b.    
     The porous monolithic blocks  24   a ,  24   b  may be produced using a freezing casting method using a plurality of porous particles  51  shown in  FIG. 5 . Alternatively, the monolithic blocks  24   a ,  24   b  may be produced by a freezing foaming method using the plurality of porous particles  51 , a sintering method using the plurality of porous particles  51 , a ceramic foaming method using the plurality of porous particles  51 , or a self-curing binding technique using the plurality of porous particles  51 . The porous particles  51  comprise second pores  28 . The size or diameter of the second pores  51  are preferably less than 1 nm. 
     For the aforementioned methods, an appropriate mold  61 , as shown in  FIG. 6 , may be used. Particularly, the mold  61  is made from a material appropriate for the specific method. In particular, each porous monolithic block  24   a ,  24   b  may be made utilizing an individual mold  61 . 
     For instance, if the porous monolithic blocks  24   a ,  24   b  are made utilizing the freezing casting method, then the mold  61  may at least partly be made from PTFE (Polytetrafluorethylen). 
     For instance, if the porous monolithic blocks  24   a ,  24   b  are made utilizing the freezing foaming method, then the mold  61  may at least partly be made from silicon rubber. 
     Preferably, the porous particles  51  are comprised or consist of a plurality of porous zeolite particles. 
     In the present embodiment, the shape of the first and second sub-enclosures  23   a ,  23   b  differ. 
     In particular, the shape of the porous monolithic block  24   a ,  24   b  are adapted to the shape of the relevant sub-enclosures  23   a ,  23   b , i.e. the shape of the first porous monolithic block  24   a  is adapted to the shape of the first sub-enclosure  23   a , and the shape of the second porous monolithic block  24   b  is adapted to the shape of the second sub-enclosure  23   b . When using one of the aforementioned methods to produce the porous monolithic blocks  24   a ,  24   b , then, for instance, the mold  61  can be adapted to the shape of the relevant sub-enclosure  23   a ,  23   b.    
     The enclosure  23  may have a contour. More specifically, the surface of the enclosure  23  facing towards the porous monolithic blocks  24   a ,  24   b  may have the contour. Preferably, the porous monolithic blocks  24   a ,  24   b  are mounted into the enclosure  23  in a form-fit manner corresponding to the contour of the enclosure  23 . 
     In the present embodiment, the first sub-enclosure  23   a  has a first contour  26   a  and the second sub-enclosure  23   b  has a second contour  26   b . Preferably, the first porous monolithic block  24   a  is mounted into the first sub-enclosure  23   a  in a form-fit manner corresponding to the first contour  26   a  of the first sub-enclosure  23   a , and the second porous monolithic block  24   b  is mounted into the second sub-enclosure  23   b  in a form-fit manner corresponding to the second contour  26   b  of the second sub-enclosure  23   b.    
     When using one of the aforementioned methods to produce the porous monolithic blocks  24   a ,  24   b , then, for instance, each porous monolithic block  34   a ,  24   b  is made using its specific mold  61 . These molds  61  may preferably each have a contour  62  which corresponds to the contour  26   a ,  26   b  of the relevant sub-enclosure  23   a ,  23   b.    
       FIG. 7  summarize, by means of a flow chart, embodiments how to manufacture the loudspeaker  21  and the mobile phone  1 , respectively. 
     For manufacturing the loudspeaker  21  or the mobile device  1 , the plurality of particles  51  may be provided, step A of the flow chart. 
     Then, the porous monolithic blocks  24   a ,  24   b  are produced by utilizing the plurality of particles  51 , step B of the flow chart, particularly by means of one of the aforementioned methods and particularly by means of the mold  61 . 
     Then, the porous monolithic blocks  24   a ,  24   b  are mounted into the enclosure  23 , particularly into the first and second sub-enclosures  23   a ,  23   b , step C of the flow chart. 
     If utilizing, for instance, the freezing casting method, then the porous monolithic blocks  24   a ,  24   b  may be made by providing an appropriate binder for a freezing casting method, and the mold  61  whose contour  62  corresponds to the contour  26   a ,  26   b  of the first and second sub-enclosure  23   a ,  23   b . Then, the binder and the plurality of particles  51  may be mixed and this mixture may be filled into the mold  61 . Then, the mold  61  filled with the mixture of the plurality of particles  51  and the binder is frozen in order to produce the relevant monolithic block  24   a ,  24   b . Then, the mold  61  is removed from the porous monolithic block  24   a ,  24   b.    
     If utilizing, for instance, the freezing foaming method, then the porous monolithic blocks may be made by providing an appropriate binder for a freezing foaming method, the mold  61  whose contour  62  corresponds to the contour  26   a ,  26   b  of the first and second sub-enclosure  23   a ,  23   b . Then, the binder and the plurality of particles  51  may be mixed and this mixture may be filled into the mold  61 . Then, the ambient pressure around the mold  61  filled with the mixture of the plurality of particles  51  and the binder is reduced in order to produce the relevant porous monolithic block  24   a ,  24   b . Then, the mold  61  is removed from the porous monolithic block  24   a ,  24   b.    
     If utilizing, for instance, the sintering method, then the porous monolithic blocks  24   a ,  24   b  may be made by providing an appropriate binder for a sintering method, and the mold  61  whose contour  62  corresponds to the contour  26   a ,  26   b  of the first and second sub-enclosure  23   a ,  23   b . Then, the binder and the plurality of particles  51  may be mixed and this mixture may be filled into the mold  61 . Then, the mold  61  filled with the mixture of the plurality of particles  51  and the binder is heated in order to produce the relevant porous monolithic block  24   a ,  24   b . During the heating, the binder burns at least partially. For example, two different kinds of binders may be used. One type of binder is a temporary binder which burns during the heating creating the first pores  27 . Another type of binder may not burn during the heating. Then, the mold  61  is removed from the porous monolithic block  24   a ,  24   b . Alternatively, the foaming of the plurality of particles  51  can also be achieved by a ceramic foaming method. 
     If utilizing, for instance, the self-curing binding method, then the porous monolithic blocks  24   a ,  24   b  may be made by providing a protein foam as a structuring agent, an appropriate binder, and the mold  61  whose contour  62  corresponds to the contour  26   a ,  26   b  of the first and second sub-enclosure  23   a ,  23   b . Then, the protein foam, the binder and the plurality of particles  51  may be mixed and this mixture may be filled into the mold  61 . Then, one has to wait until the mixture filled into the mold  61  self-cures in order to produce the relevant porous monolithic block  24   a ,  24   b . Then, the mold  61  is removed from the porous monolithic block  24   a ,  24   b.    
     Although modifications and changes may be suggested by those skilled in the art, it is the intention of the invention to embody within the patent warranted hereon all changes and modifications as reasonably and properly come within the scope of his contribution to the art.