Patent Publication Number: US-2019174225-A1

Title: Loudspeaker

Description:
FIELD OF THE INVENTION 
     The present invention relates to the field of sound reproduction systems and in particular it relates to a loudspeaker. 
     PRIOR ART 
     A loudspeaker is a compact sound system that contains one or more acoustic transducers, or speakers, adapted to convert an electrical audio signal into a sound. The prior art loudspeakers generally include a container, called box or cabinet, and one or more speakers attached to the container. 
     In a loudspeaker, the role of the container is to prevent the sound waves coming from the back of a speaker from interfering destructively with those emitted from the front part of the speaker. The sound waves emitted from the back are in fact out of phase by 180° compared to those emitted from the front, therefore without a container these waves typically cause cancellations that significantly degrade the level and quality of sound at low frequencies. 
     Generally, the container of a loudspeaker is a closed box-like container and is provided on a front wall, called baffle, with one or more mounting openings that allow attaching the speakers to the container. 
     If, as almost always happens, loudspeakers comprise multiple speakers of different type, such as a speaker for high frequencies (for example comprising a dome tweeter or a compression driver) and a speaker for the low or low and medium frequencies (such as a woofer or a midwoofer), mounting the speakers to the container does not allow aligning the acoustic centres of the speakers. This results in a time delay between the acoustic radiation emitted by the speakers and therefore different arrival times. This is a problem from a performance point of view, so if one wants to keep a desired level of performance it is necessary to carry out some corrections on the electric signals that feed the speakers. 
     The object of the present description is to provide a loudspeaker that allows solving, or at least partly reducing, the drawbacks described above with reference to the loudspeakers of the prior art described above. 
     This object is achieved by a loudspeaker as generally defined in claim  1 . Preferred and advantageous embodiments of the above loudspeaker are defined in the dependent claims. 
     The invention will be better understood from the following detailed description of a particular embodiment thereof, made by way of an example and therefore in no way limiting, with reference to the accompanying drawings briefly described in the following paragraph. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a plan front elevation view of a first non-limiting embodiment of a loudspeaker, wherein the loudspeaker comprises a container and a mounting panel to which a plurality of speakers are attached. 
         FIG. 2  is a perspective top angle view of the loudspeaker in  FIG. 1  from which the mounting panel and therefore also the speakers attached thereto have been removed. 
         FIG. 3  shows a plan lateral sectional view of part of the loudspeaker shown in  FIG. 1 , where the section plane is denoted by B-B in  FIG. 1 . 
         FIG. 4  shows a plan view of a part of the loudspeaker in  FIG. 1 . 
         FIG. 5  shows a perspective view of a part of the loudspeaker in  FIG. 1 . 
         FIG. 6  shows a plan sectional view of a part of the loudspeaker in  FIG. 1 . 
         FIG. 7  shows a plan sectional view of a part of the loudspeaker in  FIG. 1 . 
         FIG. 8  shows a plan front elevation view of a second non-limiting embodiment of a loudspeaker. 
         FIG. 9  shows a perspective view of a part of the loudspeaker in  FIG. 9 . 
         FIG. 10  shows a sectional view of a part of the loudspeaker in  FIG. 9 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows an exemplary non-limiting embodiment of a loudspeaker  1 . In the particular embodiment shown, loudspeaker  1  is in particular a monitor loudspeaker, i.e. a loudspeaker intended to be placed on a floor of a stage during a concert or a musical or theatrical show, generally live. As will be explained better in the remainder of the present description, the teachings proposed herein are also applicable to other types of loudspeakers, whereby the scope of protection should not be considered limited to monitor loudspeakers. 
     Loudspeaker  1  comprises a container  2  provided with a front opening  3  delimited by at least two opposite edges  4 ,  5  of container  2 . In the particular example shown, the front opening  3  that is only partially visible in  FIG. 1  while is better visible in  FIG. 2  is a quadrangular, preferably rectangular slot. According to an advantageous embodiment from the point of view of acoustic performance, container  2  is preferably made of wood or mostly wood with some parts of other materials, such as plastic or metallic materials. In alternative embodiments, container  2  may be made of a material other than wood, such as a plastic or metal, or any other material appropriate to the use. For example, container  2  can be made of aluminum, ABS or fiberglass. 
     Loudspeaker  1  further comprises at least a first speaker  30 ,  31  and at least a second speaker  31  accommodated into container  2 . The first speaker  30  is, or comprises, a woofer or a midwoofer and the second speaker  31  is, or comprises, a dome tweeter or a compression driver. In the particular non-limiting example shown in  FIG. 1 , loudspeaker  1  comprises three speakers  30 ,  31 , according to a configuration that a man skilled in the art calls D&#39;Appolito configuration. This configuration is also known as MTM (acronym of midwoofer-tweeter-midwoofer). In this configuration, a tweeter (i.e. a speaker for high frequencies, meaning for example both a compression driver and a dome tweeter) is interposed between two woofers (i.e. 2 speakers for low frequencies), or between two mid-ranges (i.e. two speakers for midrange frequencies) or between two mid-woofers (i.e. speakers for medium and low frequencies). For the purposes of the present description, high frequency speaker, medium frequency speaker, low frequency speaker, and medium-low frequency speaker are expressions that involve well known features to a man skilled in the art which do not require additional details about the specific frequency ranges of interest. Loudspeaker  1  further comprises a mounting panel  20  to which the first and the second speaker  30 ,  31  are fixed. The mounting panel  20  is a baffle of loudspeaker  1 . Preferably, the mounting panel  20  acts as a support element for the first and second speaker  30 ,  31 . Advantageously, the first and the second speaker  30 ,  31  are fixed inside container  2  behind the mounting panel  20 . In other words, the first and the second speaker  30 ,  31  are closed in the container  2  behind the front opening  3  of container  2 . In the particular non-limiting example shown in  FIG. 1 , to the mounting panel  20  are attached two woofer or mid-woofer speakers  30  between which a high frequency speaker  31  is interposed, preferably meaning a compression driver or a dome tweeter. Conveniently, the mounting panel  20  includes for each speaker  30 ,  31  a respective through opening  23 ,  21 . In the particular example shown in  FIGS. 1-7 , the mounting panel comprises three through openings  21 ,  23 . Preferably, the through openings  23  for the two woofer or midwoofer speakers  30  are smaller than the size of the membranes of such speakers  30 . This also applies in the case where only one woofer or midwoofer speaker  31  is provided in addition to the second speaker  31 . 
     According to an advantageous embodiment, container  2  of speaker  1  comprises a fixing guide with a guide axis A-A. Preferably, the first and second speaker  30 ,  31  are arranged axially spaced along the guide axis A-A. In the above advantageous and non-limiting embodiment, the mounting panel  20  is a slide slidably received in the fixing guide to close the front opening  3 . 
     With reference to  FIGS. 3 and 5  in loudspeaker  1 , the fixing guide comprises two opposite fixing channels  6  parallel to the guide axis A-A. Two end portions  26  of the mounting panel  20  are each inserted in a respective fixing channel  6 . Preferably, the end portions  26  have a peripheral edge that in a transverse plane to the axis A-A is rounded. 
     According to an advantageous embodiment, the fixing guide is integrated into the walls of container  2 . In the particular example shown, this is achieved thanks to the fact that the fixing channels  26  are recesses made in the walls of container  2 , preferably arranged opposite to each other with respect to the front opening  3  into container  2 . 
     According to a particularly advantageous embodiment from the point of view of the assembly operations, container  2  comprises a central body  7  at least partly hollow and two side walls  8 ,  9  mutually arranged at opposite sides with respect to the central body  7  and at least one of the side walls  8 ,  9  comprises an opening  118  transverse to the guide axis A-A. The assembly made up by the mounting panel  20  and the at least one speaker  30 ,  31  is extractable through the transverse opening  118  by sliding the mounting panel  20  with respect to the central body  7  along the guide axis A-A. In this way, the mounting panel  20  can be slidably inserted into container  1  by crossing one of the two side walls  8 ,  9  to be fixed to container  1  and/or to be then slidably extracted during inspection and/or maintenance operations. Preferably, in the above embodiment, loudspeaker  1  comprises at least one closing device  19  fixed to the side wall  9  which comprises the transverse opening  118  for closing said transverse opening and preventing a sliding of the mounting panel  20  along the guide axis A-A, thereby locking the position of the mounting panel  20  with respect to the central body  7 . The closing device  19  for example is a plastic or metal plate. Preferably, loudspeaker  1  comprises removable fasteners, such as at least one screw and at least one respective hole, adapted to removably fix the closing device  19  to the side wall  9 . 
     The foregoing can optionally be applied also to the side wall  8 . 
     According to a preferred embodiment, the side walls  8 ,  9  are flat walls. Preferably, at least one of the side walls  8 ,  9  comprises a blind or through recess  18 . Such a recess  18  may be shaped as an ergonomic hand gripping element and in the specific example shown is a through recess with a curved slot shape. 
     According to an advantageous embodiment, the mutually opposite edges delimiting the front opening  3  extend each by a length equal to the distance between the side walls  8 ,  9 . In other words, in this embodiment, the front opening  3  is laterally delimited by said side walls  8 ,  9 . 
     According to an advantageous embodiment, the mounting panel  20  comprises a protective screen, such as a grid, not shown in the figures, fixed to the mounting panel  20 . Preferably, the above grid is a metal grid and is covered by a waterproof and acoustically transparent foam. For example, this protective screen has a flat central part and two side edges folded, for example perpendicular to the central part. By suitably providing two mutually parallel recesses  27  in the mounting panel  20  it is possible to couple the protective screen to the mounting panel  20  and then insert the assembly thus formed in container  2  by sliding the opposite edges  26  of the panel into the fixing guide, i.e. in the fixing channels  6 . 
     According to a preferred embodiment, container  2 , and preferably the central body  7  of container  2 , includes a plurality of monobloc portions mutally aligned along the guide axis A-A and juxtaposed and fixed, for example through fasteners that cross them along a direction parallel to the guide axis A-A. The fixing between the monobloc portions can be achieved through pins that cross through openings crossing the monobloc portions. The end portions of the pins can be threaded so as to tighten the monobloc portions by means of nuts screwed to the threads (if the threads of the pins are external) or screws screwed into the threads (if the threads of the pins are internal). The monobloc portions for example are made of wood with carving operations, starting from a piece of solid wood, such as with a pantograph. For example, the monobloc portions are made through a processing technique called empty for full. Alternatively, for example if made of plastic or metal, the monobloc portions may be made by moulding. 
     Container  2 , preferably the central body  7 , comprises two front walls  10 ,  11  arranged on opposite sides with respect to the front opening  3 . The front walls  10 ,  11  define an acoustic waveguide G 1  diverging between an inlet throat and an outlet mouth and the front opening  1  of container  3  represents the inlet throat of the acoustic waveguide G 1 . In  FIG. 6 , the dashed axis O-O indicates the lying plane of the outlet mouth of the acoustic waveguide G 1 . This advantageously allows fixing tweeter  31  for example to the mounting panel  20  (meaning for example either a compression driver or a dome tweeter) and a woofer  30  or a mid-woofer  30 , each facing a respective opening  21 ,  23  so as to obtain that the acoustic waves emitted by the two sources  30 ,  31 , that is, by the speakers  30 ,  31  are at the outlet of loudspeaker  1  in a time alignment relation. 
     According to a particularly advantageous embodiment, the front walls  10 ,  11  are two curved walls. Preferably, the front walls  10 ,  11  outwards of container  2  are convex. More preferably, the front walls  10 ,  11  inwards of container  2  are concave. In other words, each of front walls  10 ,  11  defines one or more respective cavities, or recesses,  40 ,  41  inside container  2 . 
     According to a preferred and non-limiting embodiment, at least one of the front walls  10 ,  11 , in the example of  FIGS. 1-7  the front wall  11 , comprises at least one bass reflex through opening  11  adapted to allow a fluidic communication between the inside and the outside of container  2 . Preferably, the above bass reflex opening  111  is quadrangular, for example rectangular. Preferably, the above at least one front wall  11  comprises an array of bass reflex through openings  111  extending along a direction parallel to said guide axis A-A. It should be noted that in the exemplary non-limiting embodiment of  FIGS. 1-7  there is an array of six bass reflex through openings  111  on the front wall  11 . 
     In the embodiment in  FIGS. 1-7 , loudspeaker  1  is a monitor loudspeaker and the front walls  10 ,  11  have mutually different shapes. One of the front walls, in particular the front wall  11 , is joined to a flat wall  112  of the central body  7  that serves as a support base for loudspeaker  1 . 
     In an alternative embodiment to that described above and for example shown in  FIGS. 9-10 , the front walls  10 ,  11  have mutually equal or substantially equal shape. 
     According to a particularly advantageous embodiment, loudspeaker  1  comprises a least one speaker  30 ,  31  comprising a compression driver  31 ′ or a dome tweeter  31 ′ and a horn  31 ″ housed within container  2 . Horn  31 ″ has an inlet throat adapted to receive an acoustic radiation emitted by the compression driver  31 ′ or the dome tweeter  31 ′ and an outlet mouth opposite the inlet throat. Horn  31 ″ is fixed to the mounting panel  20 . As a whole, the compression driver  31  or dome tweeter  31  and horn  31 ″ constitute a tweeter of loudspeaker  1 , i.e. a speaker for high frequencies. Advantageously, the outlet mouth of horn  31 ″ is aligned with the inlet throat of the diverging acoustic waveguide G 1  of container  2 . Preferably, the outlet mouth of horn  31 ″ has a width equal to the distance between the opposite edges  4 ,  5  of container  2 . 
     According to a particularly advantageous embodiment, horn  31 ″ has two inner walls mutually opposite and diverging and joined with continuity each to a respective front wall  10 ,  11  to form a single acoustic waveguide G 2 , G 1  extending from the inlet throat of horn  31 ″ along the acoustic guide G 2  defined by the same horn  31 ″ to the outlet mouth of the acoustic waveguide G 1  of container  2 . Preferably, such a single acoustic waveguide G 2 , G 1  has a cross-section continuously diverging along transverse planes, particularly perpendicular, to the front walls  10 ,  11 , such as shown in  FIG. 6 . 
     As explained above, the teachings described herein are not limited to a monitor type loudspeaker  1 . With reference to  FIGS. 8-10 , a second non-limiting embodiment is shown wherein loudspeaker  1  has a column container  2 . Loudspeaker  1  in  FIGS. 8-10  differs from loudspeaker  1  described with reference to  FIGS. 1-7  primarily in that the front walls  10 ,  11  of container  2  are mutually equal, in the provision of two arrays of bass reflex openings  111  and in a different arrangement of speakers  30 ,  31 . Moreover, embodiments were also shown with three speakers, but there is no constraint on the number of speakers, which can be from a minimum of two up to a large integer. Moreover, single loudspeakers have also been shown and described intended are to be placed on a surface, but clearly it is also possible to implement suspended modular systems of the line-array type in which multiple loudspeakers of the type described above are stacked on top of each other. 
     From the foregoing it is clear that a loudspeaker of the type described above allows fully achieving the objects set out in terms of overcoming the drawbacks of the prior art. 
     The principle of the invention being understood, the manufacturing details and the embodiments may widely vary compared to what described and illustrated by way of a non-limiting example only, without departing from the scope of the invention as defined in the accompanying claims.