Abstract:
A loudspeaker arrangement for a plurality of MEMS loudspeakers for generating sound waves in the audible wavelength spectrum includes a housing, which has a sound conduction cavity and at least one sound outlet opening, and at least two MEMS loudspeakers, arranged in the interior of the housing opposite and spaced apart from each other by the sound conduction cavity. Each MEMS loudspeaker has a cavity in the region of their opposite faces. The loudspeaker arrangement includes a shielding wall for acoustically decoupling the two MEMS loudspeakers from each other. The shielding wall is arranged in the interior of the housing between the two MEMS loudspeakers such that the sound conduction cavity is subdivided into a first and a second a cavity region respectively associated with one of the two MEMS loudspeakers

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a loudspeaker arrangement for multiple MEMS loudspeakers for generating sound waves in the audible wavelength spectrum. 
         [0002]    The term “MEMS” stands for microelectromechanical systems. A microphone arrangement with a first and a second transducer is known from US 2012/0039499 A1, whereas such transducers are opposite to each other and have a common volume. With such a design, the sound waves of the transducers can interfere with each other, which can have negative effects on the quality of the system, such that this MEMS arrangement, which is favorable in terms of manufacturing technology, is unsuitable for loudspeaker applications. 
         [0003]    Thus, the task of the present invention is to provide a loudspeaker arrangement to be simply manufactured with good sound quality. 
       SUMMARY OF THE INVENTION 
       [0004]    The task of the present invention is achieved by a loudspeaker arrangement with the characteristics described below. 
         [0005]    A loudspeaker arrangement for MEMS loudspeakers for generating sound waves in the audible wave spectrum is proposed. The loudspeaker arrangement features a housing and at least two MEMS loudspeakers. The housing features a sound-conducting hollow and at least one sound outlet. The two MEMS loudspeakers are located opposite to each other and are spaced apart from each other through the sound-conducting hollow in the interior of the housing. In the area of their side turned away from each other, each of the MEMS loudspeakers has a cavity. The term “cavity” is to be understood as a hollow, by means of which the sound pressure of the MEMS loudspeakers can be amplified. The loudspeaker arrangement comprises a shielding wall for acoustically decoupling the two MEMS loudspeakers from each other. The shielding wall is arranged in the interior of the housing between the two MEMS loudspeakers in such a manner that the sound-conducting hollow is subdivided into a first hollow plenum and second hollow plenum assigned to one of the two MEMS loudspeakers. The sound waves emerging from the MEMS loudspeakers hit the shielding wall and are reflected by it. Thus, the sound waves introduced into one of the two hollow plenums cannot penetrate into the other MEMS loudspeaker, in particular into the other hollow plenum. Thus, the two MEMS loudspeakers turned towards each other are acoustically decoupled from each other. Thus, the sound waves of each of the two MEMS loudspeakers cannot adversely affect the acoustic quality of the respective opposite MEMS loudspeaker. Across the assigned first or second hollow plenum, the sound waves are conducted in the direction of the sound outlet and may emerge from the housing through this sound outlet. 
         [0006]    It is advantageous if, in a side view of the loudspeaker arrangement, the shielding wall extends, starting from a first inner side surface of the sound-conducting hollow, at least beyond the two MEMS loudspeakers and/or parallel to them in the sound-conducting hollow. Here, the first inner side surface is located, in particular, opposite the sound outlet. In order to effect the acoustic decoupling of the two MEMS loudspeakers from each other, the sound waves must be shielded from each other. Therefore, the shielding wall must extend at least across the full length and width of the MEMS loudspeakers, in order to avoid at least a direct impact of the foreign sound. 
         [0007]    In its edge area, the shielding wall is advantageously arranged on the inner surface of the sound-conducting hollow in a direct and/or acoustically sealing manner. In this case, essentially the entire circumference of the shielding wall is arranged directly thereon. In order to shield the sound waves of the two MEMS loudspeakers from each other, in particular to decouple them acoustically, the shielding wall must be formed in such a manner that the sound waves cannot run around them undesirably. 
         [0008]    An additional advantage is provided if the housing comprises a sound-conducting channel, by means of which the sound waves, which can be introduced by the respective MEMS loudspeaker, of the two hollow plenums that are separated from each other by the shielding wall, can be brought together. Thus, the sound can be amplified and/or selectively steered in one direction. 
         [0009]    Advantageously, the sound-conducting channel is arranged in the area of a first opening of the first hollow plenum and a second opening of the second hollow plenum. Thus, the sound waves can be conducted from the two MEMS loudspeakers, starting from their respective hollow plenums, into the sound-conducting channel through the associated openings. 
         [0010]    It is also advantageous if the sound-conducting channel is connected at its one end to the sound-conducting hollow and/or at its other end to the sound outlet. Thereby, the sound channel is connected, in particular, to both hollow plenums of the sound-conducting hollow. The sound-conducting channel preferably extends, starting from a second inner side surface of the sound-conducting hollow opposite the first inner side surface, up to the sound outlet. At this, it runs in particular in a straight line. Thus, the sound generated by the MEMS loudspeakers can be selectively steered in one direction or to one side of the loudspeaker arrangement. 
         [0011]    In addition, it is advantageous if the shielding wall extends, starting from the first inner side surface, to the area of the sound-conducting channel. Preferably, the shielding wall ends at this area or extends partially into it. By means of such a formation of the shielding wall, the sound waves in the two hollow plenums can be decoupled from each other completely up to the sound-conducting channel, such that the two MEMS loudspeakers cannot adversely affect each other. 
         [0012]    Advantageously, the shielding wall and/or the sound-conducting channel is/are arranged in the middle of the housing and/or in a coaxial manner relative to each other. In addition, or alternatively, the thickness of the shielding wall is smaller than the width of the sound-conducting channel. At this, the shielding wall and the sound-conducting channel are arranged in particular on an axis of symmetry of the housing. Thus, the two hollow plenums for propagating the sound have the same size, and can be led outwards through the sound-conducting channel under the same conditions. At this, the thickness of the shielding wall should be less than the width of the sound-conducting channel, since, otherwise, the sound waves could not enter the sound-conducting channel. In doing so, the path would be closed from the shielding wall and the second inner side surface. 
         [0013]    An additional advantage is provided if the shielding wall is produced in one piece together with the housing. Silicon is recommended as the material. Alternatively, it is also conceivable for the shielding wall and the housing to be separate components, whereas, preferably, the shielding wall, in particular with its edge area, is connected to the housing in a positively locking, force-fitting and/or firmly bonded manner. 
         [0014]    Furthermore, it is advantageous if the shielding wall and the housing are produced from materials different from each other, whereas, preferably, the material of the shielding wall features a stiffness that is higher compared to the material of the housing. A high degree of stiffness can ensure that the shielding wall is not itself stimulated to vibrate, and as a result of this the other MEMS loudspeaker is not undesirably influenced. 
         [0015]    The housing is advantageously made of silicon and/or the shielding wall is made of a metal, in particular aluminum, a ceramic material and/or a composite material. The housing is produced in particular in layers. The circuit boards of the MEMS loudspeaker arrangement are preferably constructed in a sandwich-like manner from a multiple number of layers that are arranged one above the other and/or connected to each other. In this way, the entire loudspeaker arrangement, including the housing, and the shielding wall along with MEMS loudspeakers integrated thereon like an inlay can be manufactured by means of a manufacturing method. Thus, the loudspeaker arrangement can be formed in a cost-effective and highly space-saving manner. 
         [0016]    In addition, it is also advantageous if the housing comprises two housing halves that are connected to each other, each of which preferably receives one of the two MEMS loudspeakers. In this case, the housing halves advantageously feature one of the two hollow plenums, whereas the shielding wall is arranged and/or fastened in its connecting area. In doing so, the fastening is effected in particular in a positively locking, firmly bonded and/or force-fitting manner. Thus, the housing halves can be produced in each case by means of the layer-by-layer manufacturing method, and subsequently connected to each other by means of the shielding wall, which can be an inlay. Thus, a cost-effective manufacturing process is enabled. 
         [0017]    For forming a cavity that is as large as possible, it is advantageous if the cavity of at least one MEMS loudspeaker is formed by a carrier substrate hollow of the MEMS loudspeaker itself and/or by a cavity hollow of the housing. As a result, the volume of the cavity, which is formed at least by the one MEMS loudspeaker, can additionally be increased by the volume of the cavity hollow of the housing. However, depending on the need, it is also conceivable to install the MEMS loudspeakers in a manner rotated by 180°, such that the carrier substrate hollow is oriented towards the hollow plenum. 
         [0018]    In an advantageous development, the loudspeaker arrangement comprises two loudspeaker units, each of which is preferably formed according to the preceding description, whereas the specified features can be present individually or in any desired combination. The loudspeaker units are preferably arranged one behind the other, such that the sound waves generated by the rear loudspeaker unit have to be passed through the front loudspeaker. 
         [0019]    The shielding wall of the first loudspeaker unit preferably comprises at least one through-channel extending in its longitudinal direction, through which sound waves of the second loudspeaker unit, in particular from one of its two hollow plenums, can be led through and/or to the sound outlet. It is possible to arrange a multiple number of pairs of MEMS loudspeakers in a space-saving manner within a housing, in particular one behind the other. 
         [0020]    The two hollow plenums of the second loudspeaker unit are advantageously separated from each other by means of a second shielding wall, and are each connected to the one common sound-conducting channel by means of a separate through-channel of the first shielding wall. Thus, the sound waves of the MEMS loudspeakers of the second loudspeaker unit can be decoupled from each other and conducted in the direction of the sound-conducting channel without influencing the sound waves of the first loudspeaker unit. 
         [0021]    An additional advantage is that the shielding walls of the two loudspeaker units are arranged in a manner relative to each other and/or coaxial to the sound-conducting channel, since this can reduce production costs. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    Further advantages of the invention are described in the following embodiments. The following is shown: 
           [0023]      FIG. 1  a perspective view of a first embodiment of the loudspeaker arrangement in which the smaller dashed lines schematically represent features otherwise hidden from the viewer&#39;s perspective and the larger dashed lines schematically represent the horizontally extending sectioning plane along which the sectional view depicted in  FIG. 2  is taken, 
           [0024]      FIG. 2  a side sectional view of the loudspeaker arrangement of the embodiment in  FIG. 1  with two MEMS loudspeakers and a shielding wall, 
           [0025]      FIG. 3  a second embodiment of the loudspeaker arrangement in a side sectional view with two loudspeaker units and 
           [0026]      FIG. 4  a third embodiment of the loudspeaker arrangement in a side sectional view with two loudspeaker units and two through-channels separated from each other. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]      FIG. 1  and  FIG. 2  show a first embodiment of a loudspeaker arrangement  1  in a schematic view ( FIG. 1 ) and in a top view ( FIG. 2 ) taken in a section cut by a horizontally extending plane schematically represented in  FIG. 1  by the larger dashed lines. The loudspeaker arrangement  1  comprises a housing  2 , two MEMS loudspeakers  5   a,    5   b  and a shielding wall  7 . At this, the housing  2  comprises two housing halves  17   a,    17   b,  each of which preferably receives a respective one of the two MEMS loudspeakers  5   a,    5   b.  Furthermore, the loudspeaker arrangement  1  features a sound-conducting hollow  3  and a sound outlet  4 , which is arranged at the end of a sound-conducting channel  12 . 
         [0028]    The two MEMS loudspeakers  5   a,    5   b  are arranged opposite to each other and spaced apart from each other through the sound-conducting hollow  3  in the interior of the housing  2 , in particular in each case in a housing half  17   a,    17   b.  The sound-conducting hollow  3  is subdivided into a first and second hollow plenum  8 ,  9 , each of which is disposed between the shielding wall  7  and a respective one of the two MEMS loudspeakers  5   a,    5   b . Furthermore, the sound-conducting hollow  3  is arranged centrally on an axis of symmetry  16  of the housing  2 . 
         [0029]    The two hollow plenums  8 ,  9  are separated from each other by the shielding wall  7 . The sound-conducting channel  12  is arranged in the area of a first opening  13  of the first hollow plenum  8  and a second opening  14  of the second hollow plenum  9 . Thus, the two hollow plenums  8 ,  9  open into the common sound-conducting channel  12  through their respective openings  13 ,  14 . The sound-conducting channel  12  is connected at its one end to the sound-conducting hollow  3 , in particular to the two hollow plenums  8 ,  9 , and at its other end to the sound-outlet opening  4 . Accordingly, each of the two housing halves  17   a,    17   b  receives one of the two MEMS loudspeakers  5   a,    5   b,  which in each case has one of the two hollow plenums  8 ,  9 . The shielding wall  7  is connected to the housing halves  17   a,    17   b  in particular in a positively locking, firmly bonded and/or force-fitting manner. Alternatively, however, the housing  2  can also be formed as a single part, whereas the shielding wall  7  is preferably fixed in the housing as an inlay by means of a layer-like structure of the housing  2 . 
         [0030]    A cavity  6  is assigned to the two MEMS loudspeakers  5   a,    5   b;  of these, only one is provided with a reference sign for reasons of clarity. In each case, the cavity  6  is formed by a carrier substrate hollow  18  and a cavity hollow  19  of the housing  2 . The carrier substrate hollow  18  is arranged on the side of the MEMS loudspeakers  5  turned away from the sound-conducting hollow  3 . In the illustrated first embodiment, the cavity hollow  19  of the housing  2  directly adjoins the carrier substrate hollow  18 . 
         [0031]    The shielding wall  7  extends from the first inner side surface  10  of the sound-conducting hollow  3 , starting through the two MEMS loudspeakers  5 , beyond a second inner side surface  15  of the sound-conducting hollow  3 . The first inner side surface  10  is arranged on the side of the housing  2  opposite the sound-conducting channel  12 . The second inner side surface  15  faces the first inner side surface  11  and is arranged in particular in the area of the first and second openings  13 ,  14  of the first and second hollow plenums  8 ,  9 . As shown in  FIG. 1 , the shielding wall  7  extends across the entire height and width of the housing  2 , such that the sound waves emerging from the MEMS loudspeakers  5   a,    5   b  have no possibility of arriving beyond the shielding wall  7  into the hollow plenums  8 ,  9  of the other MEMS loudspeaker. For this purpose, the shielding wall  7  is furthermore connected to the housing  2  in a positively locking, force-fitting and/or firmly bonded manner. 
         [0032]      FIG. 3  and  FIG. 4  show a second and third embodiment of the loudspeaker arrangement  1 . Therein, the loudspeaker arrangement  1  comprises two loudspeaker units  20 ,  21 , a first and second shielding wall  23 ,  24 , at least one with the sound-conducting channel  12  and at least one through-channel  22 . Both loudspeaker units  20 ,  21  are constructed essentially like the loudspeaker arrangement  1  described in  FIGS. 1 and 2 . Accordingly, two housing halves  17  each form one loudspeaker unit  20 ,  21 . The housing halves  17  are connected to each other in a positively locking, force-fitting and/or firmly bonded manner through the first and/or second shielding wall  23 ,  24 , in such a manner that the MEMS loudspeakers  5  arranged therein are opposite to each other. The two loudspeaker units  20 ,  21  are likewise connected to each other in the longitudinal direction, in particular in a coaxial manner, in a positively locking, force-fitting and/or firmly bonded manner. 
         [0033]    On the side opposite the second loudspeaker unit  21 , the first loudspeaker unit  20  features the sound outlet  4  and the sound-conducting channel  12  connected to the sound outlet  4 . As in the first embodiment, the plenums  8 ,  9  of the MEMS loudspeakers  5  together form a sound-conducting hollow  3 , in the area of which the first shielding wall  23  is formed. The first shielding wall  23  extends from the first inner side surface  10  to the second inner side surface  15 , in particular up to the sound outlet  4 . The cavity  6  of the MEMS loudspeakers  5  is formed by the cavity hollow  19  of the housing  2 . The carrier substrate hollow  18  is arranged on the side of the MEMS loudspeakers  5  turned away from the cavity hollow  19 , whereas the orientation of the MEMS loudspeaker  5  shown in  FIG. 2  is also conceivable. 
         [0034]    The second loudspeaker unit  21  also features two openings  13 ,  14  on the side opposite the first side inner surface  10 , and is connected to the sound-conducting channel  12  through this, in particular by means of a through-channel  22 . The through-channel  22  extends from the two openings  13 ,  14  of the second loudspeaker unit  21  up to the sound-conducting channel  12 . 
         [0035]    In the embodiments shown in  FIGS. 3 and 4 , the through-channel  22  is formed in the first shielding wall  23 . In contrast to the embodiment illustrated in  FIG. 3 , the embodiment illustrated in  FIG. 4  features two through-channels  22 , which are separated from each other. With both embodiments, the second loudspeaker unit  21  features a second shielding wall  24 , as has already been described in  FIG. 1 . In accordance with the embodiment illustrated in  FIG. 4 , it extends, starting from the first inner side surface  10  of the second loudspeaker unit  21 , up to the sound-conducting channel  12 , which is arranged on the first loudspeaker unit  20 . As a result, the shielding wall  24  of the second loudspeaker unit  21  forms the two through-channels  22  separated from each other. 
         [0036]    In contrast to this, with the embodiment illustrated in  FIG. 3 , the sound waves of the second loudspeaker unit  21  are combined in the single through channel  22  and are conducted up to the sound-conducting channel  12 . 
         [0037]    The embodiment illustrated in  FIG. 4  therefore corresponds to the embodiment shown in  FIG. 3 , except for the formation of the shielding wall  7 ,  24 . However, the shielding wall  7  extends from the first inner side surface  10  of the second loudspeaker unit  21  continuously to the sound-conducting channel  12 , which is connected to the sound outlet  4  of the first loudspeaker unit  20  and is formed by the first and second shielding walls  23 ,  24 . 
         [0038]    At this, the shielding wall  7  can be integrated into the loudspeaker arrangement  1  in the layer-by-layer manufacturing method, for example, in the form of an inlay. The two mutually separated through-channels  22  extend parallel to the shielding wall  7  from the sound outlet  4  of the second loudspeaker unit  21 , in particular the first inner side surface  10  of the first loudspeaker unit  20 , down to the sound-conducting channel  12 . The sound waves of the second loudspeaker unit  21  are conducted in a manner decoupled from each other through the first or second hollow plenum  8 ,  9  of the MEMS loudspeaker  5  up to the respective opening  12 ,  13  in the area of the sound outlet  4  of the second loudspeaker unit  21 . From there, the sound waves arrive in the adjacent through-channel  22  and are conducted up to the sound-conducting channel  12 . The sound waves of the first loudspeaker unit  20  are likewise guided in a manner decoupled from the shielding wall  7  or the through-channel  22  up to the sound-conducting channel  12 . In the sound-conducting channel  12 , in particular in the area adjoining the sound outlet  4 , the sound waves of the four MEMS loudspeakers  5  meet each other, and are guided out of the housing  2  in a bundled manner. 
         [0039]    This invention is not limited to the illustrated and described embodiments. Variations within the scope of the claims, just as the combination of characteristics, are possible, even if they are illustrated and described in different embodiments. 
       LIST OF REFERENCE SIGNS 
       [0000]    
       
           1  Loudspeaker arrangement 
           2  Housing 
           3  Sound-conducting hollow 
           4  Sound outlet 
           5  MEMS loudspeaker 
           6  Cavity 
           7  Shielding wall 
           8  First hollow plenum 
           9  Second hollow plenum 
           10  First inner side surface 
           11  Inner surface of the sound-conducting hollow 
           12  Sound-conducting channel 
           13  First opening 
           14  Second opening 
           15  Second inner side surface 
           16  Axis of symmetry 
           17  Housing halves 
           18  Carrier substrate hollow 
           19  Cavity hollow 
           20  First loudspeaker unit 
           21  Second loudspeaker unit 
           22  Through-channel 
           23  First shielding wall 
           24  Second shielding wall