Patent Publication Number: US-2017359651-A1

Title: Directional Microphone System

Description:
BACKGROUND OF THE INVENTION 
     The present invention pertains to the field of acoustics and, more particularly, to a directional microphone system for capturing audio signals. There are a number of multi-element microphones on the market. Typically, such microphones are employed in large meeting or lecture rooms, halls and the like of buildings where rather large groups of people gather for speaking engagements. Of particular concern to the present invention is the type of microphones generally referred to as “ceiling microphones”. In general, with these types of microphones, no distinction is made to differentiate microphones that are actually installed at the ceiling, or those that hang down for a short distance from the ceiling. Regardless, these microphones are intended to hang relatively high above the individuals speaking. 
     For example, such a microphone system would typically be employed in a board room. When a meeting is conducted using the microphone system, various potential speakers would be seated around a boardroom table, with various microphones hanging down from the ceiling to a fixed height well above the individuals. The microphones are internally designed to aim the microphone elements downward at varying downward angles from a flat 10 degrees of downward pitch to a maximum of roughly 45 degrees from horizontal, typically from a horizontal ceiling plane. With these microphones positioned well above the individuals and relatively closer to the ceiling, typically a source of noise, the audio quality can also be compromised due to distance and impaired horizontal coverage. At this high position the microphones often pick up more ambient or surrounding noise along with the audio from the intended speaker. In addition, known microphones of this type tend to be quite large or bulky, generally being greater than two inches in diameter, resulting in a rather unpleasant eye-sore in what is intended to be an aesthetically pleasing environment. Although it is possible to mount the microphones utilizing retractable reeling mechanisms so as to enable the height of the microphones relative to the individuals to be adjusted, audio quality would be compromised under these circumstances due to the known internal microphone element configuration and the overall bulky nature of these microphones makes lowering such microphones considerably less desirable. 
     SUMMARY OF THE INVENTION 
     The directional microphone system of the invention includes a microphone assembly designed to be mounted from a ceiling or other raised surface through a reeling mechanism which is used to deploy the microphone to a lowered position just above eye level in order to obtain better audio signals. That is, the overall microphone system includes a servo-based reeler mounted to the ceiling or other raised surface mount, with the microphone assembly being attached to a cable which can be selectively extended or retracted from a housing of the servo-based reeler. With this arrangement, the microphone assembly can be readily deployed at an optimal height for audio reception, i.e., slightly above eye level height resulting in less room noise and improved audio presence. In particular in accordance with the invention, the microphone assembly includes an outer housing encapsulating multiple audio detection elements or capsules which are specifically angled relative to each other and the horizontal in order to optimize targeted audio reception. 
     In accordance with a preferred embodiment of the invention, the housing of the microphone assembly takes a spherical or ball-shaped configuration, with the spherical microphone assembly being composed of two connected machined hemispheres. The top or upper hemisphere encompasses a microphone cable anchor system including a threaded center post that restrains the microphone cable when the post is tightened into the top hemisphere. In addition, a bottom or lower hemisphere is provided with a series of openings or screens for the microphone elements. Within the housing is mounted a wishbone frame including a base secured to the bottom hemisphere and a plurality of upstanding, bifurcated legs. Preferably, each leg is angled at about 60° to the horizontal and supports a rubber grommet carrying a respect one of the audio detection elements. Most preferably, the wishbone frame includes three legs which are spaced 120° apart such that the microphone assembly incorporates three spaced and angled audio detection elements mounted in vibration isolation through the grommets in opposition to the series of openings or screens. Overall, the microphone assembly is quite small, preferably having an outer diameter of less than one inch ( 1 ″) and, more preferably, in the order of ⅞″. With this preferred arrangement, three audio detection (microphone) elements are secured through with wishbone frame, with the angle for each element preferably being preferably at 60° from horizontal which has been found to significantly enhance the ability of the microphone assembly to provide a wider horizontal coverage. 
     Additional objects, features and advantages of the invention will become more readily apparent from the detailed description presented below, when taken in conjunction with the drawings wherein like reference numerals refer to corresponding parts in the several views. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a directional microphone system including a microphone connected to a reeling mechanism constructed in accordance with the invention. 
         FIG. 2  is an exploded view of components of the microphone of  FIG. 1 . 
         FIG. 3  is a partial exploded view of outer housing components of the microphone. 
         FIG. 4  is a bottom plan view of one of the outer housing components of  FIG. 3 . 
         FIG. 5  is an assembled, perspective view of various internal components from  FIG. 2 . 
         FIG. 6  is a cross-sectional view of the microphone of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Detailed embodiments of the present invention are disclosed herein. However, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale, and some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to employ the present invention. In addition, any specific numerical value listed herein includes a margin of error of +/−5%. Accordingly, an angle of 60° includes angles between 57° and 63°. The term “about” increases the margin of error to 10%. 
     With initial reference to  FIG. 1 , a microphone system constructed in accordance with the present invention is generally indicated at  2 . Microphone system  2  includes a microphone assembly  5  connected through a cable  8  to a reeling mechanism  12 . In general, reeling mechanism  12  can take various forms known in the art, including various reelers sold by the XEDIT Corporation, such that the details thereof are not important to the particular invention. In general, however, reeling mechanism  12  is shown to include a housing  15  for cable  8  which can be selectively retracted into and deployed from housing  15  either manually or electrically. In the representative embodiment shown, housing  15  is supported from a ceiling  18  through a bracket  21 . 
     With particular reference to  FIGS. 2-4 , a preferred construction for microphone assembly  5  will now be provided. As depicted, microphone assembly  5  is spherical in shape, including a top or upper hemisphere portion  28  provided with an upper central bore  30  surrounded by a plurality of circumferentially spaced through holes  33  which are provided for venting purposes. As best shown in  FIG. 2 , top hemisphere portion  28  also establishes a lower peripheral surface  35 . Microphone assembly  5  also includes a bottom or lower hemisphere portion  37  including a lower central bore  40 , as well as a series of circumferentially spaced openings  43  provided adjacent an upper peripheral surface  46 . At this point, it should be noted that upper and lower hemisphere portions  28  and  37  can be formed from of a wide range of materials. In a preferred form, upper and lower hemisphere portions  28  and  37  are machined of metal. In addition, upper and lower hemisphere portions  28  and  37  can be attached together in various ways, with one preferred arrangement being detailed below after describing internal structure of microphone assembly  5 . 
     With particular reference to  FIG. 2 , microphone assembly  5  is preferably provided with a wishbone frame  52  including a base  54  and a plurality of upstanding legs  56 - 58 , each of which is bifurcated so as to including a first leg portion  60  and a second leg portion  61 . As shown, base  54  of frame  52  is formed with an aperture  62 . In addition to frame  52 , microphone assembly  5  employs a plurality of grommets, one of which is indicated at  67 , with each grommet  67  being made from an elastomeric material such as rubber. Mounted within a central opening formed in each grommet  67  is an audio detection element or capsule  70 . As will be detailed more fully below, microphone assembly  5  also includes a center post generally indicated at  77 . 
     As best shown in  FIG. 6 , center post  77  includes an upper end  79  which is externally threaded at  81  and mates with an internally threaded recess  83  of upper hemisphere portion  28 . Center post  77  also includes a shaft portion  86  which extends from upper end  79  and has a terminal end portion (not separately labeled) which is provided with an internally threaded bore  88 . Upper end  79  is also shown to include an internal channel  91  having a first diametric portion  93  leading to a second, angled and reduced diametric portion  95  which establishes a conductor passage. 
     As seen in this figure, cable  8  extends through central bore  30  of upper hemisphere portion  28  and has crimped or otherwise fixed thereto a fitting  98  including a flange  99 . Upper end  79  of center post  77  is threaded within recess  83 , with flange  99  being sandwiched between upper hemisphere portion  28  and a top of center post  77 , while the remainder of fitting  98  extends into first diametric portion  93  of internal channel  91 . As such, the fitting  98  is held captive to securely anchor the microphone assembly  5 . With each grommet  67  supporting a respective audio detection element  70 , an annularly reduced central portion  102  of the grommet  67  is arranged between the first and second leg portions  60  and  61  of a respective bifurcated leg  56 - 58  (also see  FIG. 5 ), with wires (not shown) extending from cable  8  being electrically connected to each audio detection element  70 . Once assembled in this manner, base  54  of frame  52  is positioned against shaft portion  86  of center post  77 , lower hemisphere portion  37  is placed about wishbone frame  52  such that upper surface  46  abuts lower peripheral surface  35  and central bore  40  is aligned with aperture  62  in base  54 . Thereafter, a mechanical fastener, such as a screw  105 , is inserted through central bore  40  and aperture  62 , and then threaded or otherwise extended into bore  88  of shaft  86  to fixedly secure upper and lower hemisphere portions  28  and  37  together with frame  52  therein. 
     With this overall arrangement, wishbone frame  52  has the generally U-shaped legs  56 - 58  arranged 120 degrees apart, with each leg  56 - 58  being angled at about 60 degrees relative to horizontal or about 30 degrees to the vertical. At the same time, the grommets  67  act as both isolation and insulation mounts for the audio detection elements or capsules  70 , while assuring that the audio detection elements  70  cannot make electrical contact with any metal of upper or lower hemisphere portions  28 ,  37 . In addition, through holes  33  provide venting to assure proper functioning of cardioid elements, and openings  43  are arranged juxtapose audio detection elements  70  to enable clean and clear audio reception. Furthermore, as indicated above, the microphone assembly  5  is quite small, preferably having an outer diameter of less than one inch (1″) and, more preferably, in the order of ⅞″. In any case, although described with reference to preferred embodiments of the invention, it should be recognized that various changes and/or modification can be made without departing from the spirit of the invention as encompassed by the claims.