Patent Publication Number: US-6993145-B2

Title: Speaker grille frame

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to audio systems. More particularly, the present invention relates to a speaker grille frame through which sound waves may travel. 
   2. Description of Prior Art 
   Conventional speaker diaphragms are typically covered with speaker grille cloth or other perforated material to protect the diaphragm from dust and other particles. The cloth is stretched very tightly over removable frames in order to minimize movement in response to airflow created by speaker excursion. Therefore, frames must be rigid enough to withstand the tension associated with tightly stretched cloth and are typically solid and quite dense. 
   Unfortunately, however, solid frames block and reflect sound waves, thereby preventing sound waves from propagating along a front surface of a speaker. This creates undesirable reflections and reduces sound quality, thereby diminishing the effectiveness of advanced surround sound systems. 
   Accordingly, there is a need for an improved speaker grille that overcomes the limitations of the prior art. 
   SUMMARY OF THE INVENTION 
   The present invention overcomes the above-identified problems and provides a distinct advance in the art of speaker grilles. More particularly, the present invention provides a speaker grille frame through which sound waves may travel. The frame is designed as part of a speaker grille for use with a speaker box. The speaker box is preferably completely conventional and includes a plurality of speakers. The grille is preferably removably mounted to the speaker box. 
   The grille broadly comprises a cloth or other perforated material and a frame to support the cloth and hold the cloth offset forwardly of the speakers. The cloth is preferably stretched taunt over the frame for minimal movement in response to speaker excursion. Thus, structural integrity of the frame is a paramount consideration. The frame includes a plurality of sidewalls defining a plurality of slots through which sound waves may travel between a smooth surface supporting the cloth and a mounting surface with which the frame mounts to the speaker box. The slots are preferably rectangular in cross-section, preferably penetrate all four sides of the frame, and may also penetrate all four corners of the frame. 
   The slots form channels through the frame which act as waveguides and allow sound waves to travel from the speakers through the frame. In this manner, the channels direct the sound waves laterally and disperse the sound waves substantially parallel to a plane of the frame and perpendicular to the speaker axes. Furthermore, the exterior perimeter of the frame may be beveled, rounded, or otherwise modified in shape, thereby sloping or otherwise modifying the channel&#39;s shape. In this case, the sound waves may be directed at various angles to the speaker axes. Thus, the grille of the present invention may be configured to direct the sound waves at various angles between perpendicular and parallel to the speaker axes, or to diffract the sound waves around the sides of the speaker box. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A preferred embodiment of the present invention is described in detail below with reference to the attached drawing figures, wherein: 
       FIG. 1  is a perspective view of a speaker grille constructed in accordance with a preferred embodiment of the present invention shown with a speaker box to which the grille may removably mount; and 
       FIG. 2  is a perspective view of a frame of the grille. 
   

   DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
   Referring to  FIG. 1 , the preferred speaker grille  10  constructed in accordance with a preferred embodiment of the present invention is illustrated with a speaker box  12 . The speaker box  12  is preferably completely conventional and includes a plurality of speaker openings  14  each accommodating one of a plurality of speakers  16 . The grille  10  is preferably removably mounted to the speaker box  12  in virtually any conventional manner. For example, the grille  10  may include pegs that fit into holes in the speaker box  12 . Alternatively, the speaker box  12  may include pegs that fit into holes in the grille  10 . 
   Referring also to  FIG. 2 , the grille  10  broadly comprises a cloth  18  or other perforated material and a frame  20  to support the cloth  18  and hold the cloth  18  offset forwardly of the speakers  16 . The cloth  18  may be glued, stapled, or attached to the frame  20  in virtually any conventional manner. The cloth  18  is preferably stretched over the frame  20 . Thus, the cloth  18  may cover the speakers  16  with minimal movement in response to air movement caused by the speaker&#39;s  16  excursion. 
   The frame  20  is preferably rectangular and approximately one half inch thick. The frame  20  includes an exterior perimeter  22  and an interior perimeter  24 . In one embodiment, the exterior perimeter  22  is approximately seven and one quarter inches wide and approximately thirteen and three quarter inches tall. In this embodiment, the interior perimeter  24  is approximately five and three quarter inches wide and approximately eleven and one half inches tall. However, these dimensions are dependent upon the size and shape of the speaker box  12 . In addition, the exterior perimeter  22  may be beveled in order to provide a smooth transition over which the cloth  18  may be stretched. 
   The frame  20  presents a substantially continuous smooth surface  26  for supporting the cloth  18  and a mounting surface  28  for mating with the speaker box  12 . A plurality of traversely extending sidewalls  29  define a plurality of slots  30  through which sound waves may travel between the smooth surface  26  and the mounting surface  28 . The slots  30  are preferably approximately one half inch wide and approximately one quarter inch deep. Each slot  30  preferably has a rectangular cross-section with a front wall  32  adjacent the smooth surface  26 , a back wall  34  adjacent the mounting surface  28 . The sidewalls  29  rigidly offset the smooth surface  26  from the mounting surface  28  in order to provide the structural integrity required to support the cloth  18 . In this regard, the sidewalls  29  are preferably approximately one eighth of an inch thick. However, the slots  30  preferably penetrate all four sides of the frame  20  and may also penetrate all four corners of the frame  20 . With this in mind, the sidewalls  29  may be tapered near the corners of the frame  20 . 
   The frame  20  may be constructed of two pieces. For example, a front piece  38  and a back piece  40  may each begin as solid fiberboard, or another suitable material. The pieces  38 , 40  may be shaped to fit the speaker box  12 . The back piece  40  is also preferably configured to mate with the speaker box  12 , and thus includes the mounting surface  28 . The slots  30  are preferably cut into a front surface of the back piece  40 , using a router, milling machine, or similar apparatus, forming the sidewalls  29  between the slots  30  and the back walls  34  separating the slots  30  from the mounting surface  28 . Then, the front piece  38  may be placed over and glued to the back piece  40  to cover the slots  30 , thereby providing the smooth surface  26  over which the cloth  18  may be stretched. Thus, the front piece  38  would include the smooth surface  26  and the front walls  32  of the slots  30 . 
   The frame  20  is preferably manufactured by first cutting the slots 30  in the back piece  40 . Second, the interior perimeter  24  is formed in both the front piece  38  and the back piece  30 . Third, the exterior perimeter  22  is formed in both the front piece  38  and the back piece  30 . Fourth, the front piece  38  and the back piece  40  are glued together. Fifth, the exterior perimeter  22  is beveled. Finally, the cloth  18  is stretched over and glued to the frame  20 . However, a slightly modified manufacturing order may be used. 
   It can be seen that the slots  30  form channels through the frame  20 . The channels act as waveguides and allow sound waves to travel from the speakers  16  through the frame  20 . The channels direct the sound waves laterally and disperse the sound waves substantially parallel to a plane of the frame  20 . Thus, the grille  10  of the present invention allows the sound waves to propagate not only along an axis of each speaker  16 , as is well known in the art, but also perpendicular to the speaker axises. Furthermore, if the exterior perimeter of the frame  20  is beveled, the front walls  32  of the slots  30  will be shorter than the back walls  34  of the slots  30 . In this case, the sound waves may be directed at an acute angle to the speaker axises. Thus, the grille  10  of the present invention may be configured to direct the sound waves at various angles to the speaker axes. 
   While the present invention has been described above, it is understood that other materials and/or dimensions can be substituted. For example, the frame  10  may be constructed of plastic or even metal, such as aluminum, and may be circular or otherwise rounded. As discussed above, the dimensions of the perimeters  22 , 24  are virtually entirely dependant upon the dimensions of the speaker box  12 . However, the dimensions of the slots  30  and the sidewalls  29  are critical to the structural integrity of the frame  20 . With this in mind, the dimensions of the slots  30  and the sidewalls  29  are related. For example, if the slots  30  are deeper, then the sidewalls  29  are preferably thicker, which can be accommodated with narrower or fewer slots  30 . Of course, these dimensions are also dependant upon the strength of the material chosen. Provided these limitations are met, the slots  30  may be between one quarter inch and one inch wide, between one eight of an inch and half an inch deep, and the sidewalls  29  may be between one sixteenth of an inch and one inch thick. These and other minor modifications are within the scope of the present invention.