Abstract:
A ball and socket joint preventing rotation of the ball about the axis of radial symmetry of the socket and restricting rotation of the ball about both axes orthogonal to the axis of radial symmetry to a predetermined angular value. The ball is irregular in shape and has grooves that receive ridges in the socket to accomplish the axial rotational restriction. The interaction of socket shape with ball shape accomplishes the rotational restrictions about the orthogonal axes. An exemplary use is for joining headset ear cups to headset side pieces to provide flexibility to accommodate a wide range of head shapes and sizes. The ball is preferably made of one piece with the headset side pieces and the socket is preferably made of one piece with the shell of the ear cup. Embodiments for head-mounted headsets and helmet-mounted headsets are disclosed.

Description:
FIELD OF ART 
     The present invention relates to a ball and socket joint specially adapted for use on a hearing protection or communication headset ear cup. More particularly, the invention relates to a ball and socket joint limited to predetermined limits about the X and Y-axes and zero degrees about the Z-axis and in which the ball can be inserted or removed only by a Z-axis force. 
     CROSS REFERENCE TO RELATED APPLICATIONS 
     None. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT 
     None. 
     BACKGROUND OF THE INVENTION 
     Headsets are widely used in industry for hearing protection, electronic communication, or both. A perennial problem in headset design is finding a way to make a mass-production headset that will fit the wide variety of head sizes and shapes. Headset ear cups that are flexibly attached to headset side pieces must be resistant to disconnecting, have a simple and inexpensive connector, and provide a range of flexibility adequate to adapt to a wide variety of head sizes and shapes. Towards those ends, the present inventors disclose the present novel invention. 
     SUMMARY OF THE INVENTION 
     In one embodiment, the invention provides a restricted ball and socket joint for a headset ear cup including: an irregular ball including: a bulb; an axis of radial symmetry; and a plurality of axial external grooves equally spaced apart around the bulb; a socket including: a circular opening having a central axis of rotation; and a plurality of ridges within the circular opening alignable to the plurality of the grooves; and where the irregular ball, when installed in the socket, is restricted from rotating about the central axis of rotation by the plurality of the ridges engaging the plurality of the grooves. The restricted ball and socket joint for a headset ear cup, further including a panel that is one of supporting the socket and of one piece with the socket. The restricted ball and socket joint for a headset ear cup, where the irregular ball further includes: a stem extending between the bulb and an object to be connected by the restricted ball and socket joint; a semi-spherical section extending axially from the stem, where the semi-spherical section includes the largest diameter of the bulb; a truncated conical section extending axially from the semi-spherical section; and a semi-spherical end piece extending axially from the truncated conical section. The restricted ball and socket joint for a headset ear cup, where the semi-spherical end piece of the irregular ball includes an axially aligned concave portion. The restricted ball and socket joint for a headset ear cup, where the socket further includes: a beveled annular edge surrounding the circular opening; an inner opposing beveled surface extending axially from the beveled annular edge; an inner cylindrical surface extending axially from the inner opposing beveled surface; and an inner semi-spherical section extending axially from the inner cylindrical surface. The restricted ball and socket joint for a headset ear cup, where each ridge of the plurality of the ridges have a generally triangular cross-section and taper bi-directionally from a junction of the inner opposing beveled surface and the inner cylindrical surface. The restricted ball and socket joint for a headset ear cup, where the inner cylindrical surface of the socket and the truncated conical section of the ball form a predetermined angle, when the ball is installed in the socket and the axis of radial symmetry of the irregular ball is aligned with the central axis of rotation of the socket, where the predetermined angle determines the limit of rotation of the irregular ball about axes orthogonal to the central axis of rotation of the socket. The restricted ball and socket joint for a headset ear cup, where the predetermined angle is twenty degrees. The restricted ball and socket joint for a headset ear cup, where a first the irregular ball is either connected to a first headset side piece or is of one piece with a first headset side piece. The restricted ball and socket joint for a headset ear cup, where a first the irregular ball is either connected to a first helmet side piece or is of one piece with a first helmet side piece. The restricted ball and socket joint for a headset ear cup, where the socket is either fixed in a shell of a headset ear cup or is of one piece with a shell of a headset ear cup. The restricted ball and socket joint for a headset ear cup, where; a first irregular ball is integral to a first headset side piece at a first end of said first headset side piece; a second irregular ball is integral to a second headset side piece at a first end of said second headset side piece; the first and second headset side pieces are connected by an adjustment band; a first socket is integral with a shell of a first headset ear cup; a second socket is integral with a shell of a second headset ear cup; the first irregular ball is installed in the first socket; and the second irregular ball is installed in the second socket to form a headset. The restricted ball and socket joint for a headset ear cup, where the first and second irregular balls are installed in the first and second sockets, respectively, only in discrete positions determined by the number and spacing of the grooves and the ridges. The restricted ball and socket joint for a headset ear cup, where; a first the irregular ball is integral with a first helmet headset side piece at a first end of the first helmet headset side piece; a second the irregular ball is integral with a second helmet headset side piece at a first end of second helmet headset side piece; the first and second helmet headset side pieces are connected to first and second bent supports, respectively, that are coupled to first and second helmet couplings, respectively, that are coupled to first and second opposing helmet attachment points, respectively, on a helmet; a first the socket is integral with a shell of a first headset ear cup; a second the socket is integral with a shell of a second the headset ear cup; the first irregular ball is installed in the first socket; and the second irregular ball is installed in the second socket to form a helmet headset. The restricted ball and socket joint for a headset ear cup, where the first and second irregular balls are installed in the first and second sockets, respectively, only in discrete positions determined by the number and spacing of the grooves and ridges. The restricted ball and socket joint for a headset ear cup, where the socket further includes: a beveled annular edge surrounding the circular opening; an inner opposing beveled surface extending axially from the beveled annular edge; an inner cylindrical surface extending axially from the inner opposing beveled surface; and an inner semi-spherical section extending axially from the inner cylindrical surface. 
     In a similar embodiment, the invention provides a restricted ball and socket joint for a headset ear cup including: an irregular ball including: a bulb; a stem extending between the bulb and an object to be connected by the restricted ball and socket joint; an axis of radial symmetry; a plurality of axial external grooves equally spaced apart around the bulb; a semi-spherical section extending axially from the stem, where the semi-spherical section includes the largest diameter of the bulb; a truncated conical section extending axially from the semi-spherical section; and a semi-spherical end piece extending axially from the truncated conical section; a socket including: a panel; a circular opening in the panel having a central axis of rotation; a beveled annular edge of the panel surrounding the circular opening; an inner opposing beveled surface extending axially from the beveled annular edge; an inner cylindrical surface extending axially from the inner opposing beveled surface; an inner semi-spherical section extending axially from the inner cylindrical surface; a plurality of ridges within the circular opening where each ridge of the plurality of ridges includes: a triangular cross-section; extension from the inner opposing beveled surface and the inner cylindrical surface; a bidirectional taper extending from a junction of the inner opposing beveled surface and the inner cylindrical surface; the plurality of ridges alignable to the plurality of the grooves; where the irregular ball, when installed in the socket, is restricted from rotating about the central axis of rotation by the plurality of the ridges engaging the plurality of the grooves; where the irregular ball is installed in the socket only in discrete positions determined by the number and spacing of the grooves and ridges; and where the inner cylindrical surface of the socket and the truncated conical section of the ball form a predetermined angle, when the ball is installed in the socket and the axis of radial symmetry of the irregular ball is aligned with the central axis of rotation of the socket, where the predetermined angle determines the limit of rotation of the irregular ball about axes orthogonal to the central axis of rotation of the socket. The restricted ball and socket joint for a headset ear cup, further including EITHER: the headset ear cup, further including: a first irregular ball is integral with a first headset side piece at a first end of the first headset side piece; a second irregular ball is integral with a second headset side piece at a first end of the second headset side piece; the first and second headset side pieces are connected by an adjustment band; a first socket is integral with a shell of a first headset ear cup; a second socket is integral with a shell of a second headset ear cup; the first irregular ball is installed in the first socket; the second irregular ball is installed in the second socket to form a headset; and where the first and second irregular balls are installed in the first and second sockets, respectively, only in discrete positions determined by the number and spacing of the grooves and ridges; OR the headset ear cup, further including: a first irregular ball integral with a first helmet headset side piece at a first end of said first helmet headset side piece; a second the irregular ball is integral with a second helmet headset side piece at a first end of said second helmet headset side piece; the first and second helmet headset side pieces are connected to first and second bent supports, respectively, that are coupled to first and second helmet couplings, respectively, that are coupled to first and second opposing helmet attachment points, respectively, on a helmet; a first socket is integral with a shell of a first the headset ear cup; a second socket is integral with a shell of a second the headset ear cup; the first irregular ball is installed in the first socket; the second irregular ball is installed in the second socket to form a helmet headset; and where the first and second irregular balls are installed in the first and second sockets, respectively, only in discrete positions determined by the number and spacing of the grooves and ridges. 
     In another similar embodiment, the invention provides a restricted ball and socket joint for a headset ear cup including: an irregular ball including: a bulb; a stem extending between the bulb and an object to be connected by the restricted ball and socket joint; an axis of radial symmetry; a plurality of axial external grooves equally spaced apart around the bulb; a semi-spherical section extending axially from the stem, where the semi-spherical section includes the largest diameter of the bulb; a truncated conical section extending axially from the semi-spherical section; and a semi-spherical end piece extending axially from the truncated conical section; a socket including: a panel; a circular opening in the panel having a central axis of rotation; a beveled annular edge of the panel surrounding the circular opening; an inner opposing beveled surface extending axially from the beveled annular edge; an inner cylindrical surface extending axially from the inner opposing beveled surface; an inner semi-spherical section extending axially from the inner cylindrical surface; a plurality of ridges within the circular opening where each ridge of the plurality of ridges includes: a triangular cross-section; extension from the inner opposing beveled surface and the inner cylindrical surface; a bidirectional taper extending from a junction of the inner opposing beveled surface and the inner cylindrical surface; the plurality of ridges alignable to the plurality of the grooves; where the irregular ball, when installed in the socket, is restricted from rotating about the central axis of rotation by the plurality of the ridges engaging the plurality of the grooves; where the irregular ball is installed in the socket only in discrete positions determined by the number and spacing of the grooves and ridges; and where the inner cylindrical surface of the socket and the truncated conical section of the ball form a predetermined angle, when the ball is installed in the socket and the axis of radial symmetry of the irregular ball is aligned with the central axis of rotation of the socket, where the predetermined angle determines the limit of rotation of the irregular ball about axes orthogonal to the central axis of rotation of the socket. The restricted ball and socket joint for a headset ear cup, where the semi-spherical end piece of the irregular ball includes an axially aligned concave portion. 
    
    
     
       DESCRIPTION OF THE FIGURES OF THE DRAWINGS 
       The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and 
         FIG. 1A  is a perspective view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup, according to a preferred embodiment of the present invention; 
         FIG. 1B  is a perspective view illustrating an exemplary embodiment of the socket of the restricted ball and socket joint for headset ear cup, according to a preferred embodiment of the present invention; 
         FIG. 2  is a front elevation view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup of  FIG. 1A  in a first exemplary configuration, according to a preferred embodiment of the present invention; 
         FIG. 3  is a front elevation view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup of  FIG. 1A  in a second exemplary configuration, according to a preferred embodiment of the present invention: 
         FIG. 4  is a front elevation view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup of  FIG. 1A  in a third exemplary configuration, according to a preferred embodiment of the present invention; 
         FIG. 5  is a front elevation view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup of  FIG. 1A  in a fourth exemplary configuration, according to a preferred embodiment of the present invention 
         FIG. 6  is a perspective view illustrating an exemplary embodiment of the irregular ball of the restricted ball and socket joint for headset ear cup of  FIG. 1A , according to a preferred embodiment of the present invention; 
         FIG. 7  is a front elevation view illustrating an exemplary embodiment of the irregular ball of the restricted ball and socket joint for headset ear cup of  FIG. 1A , according to a preferred embodiment of the present invention; 
         FIG. 8  is a front elevation view illustrating an exemplary embodiment of the irregular ball of the restricted ball and socket joint for headset ear cup of  FIG. 1A , according to a preferred embodiment of the present invention; 
         FIG. 9A  is a perspective view illustrating an exemplary embodiment of a socket of the restricted ball and socket joint for headset ear cup of  FIG. 1A , according to a preferred embodiment of the present invention; 
         FIG. 9B  is a front elevation view illustrating an exemplary embodiment of a socket of the restricted ball and socket joint for headset ear cup of  FIG. 1A , according to a preferred embodiment of the present invention; 
         FIG. 9C  is a side elevation view illustrating an exemplary embodiment of a socket of the restricted ball and socket joint for headset ear cup of  FIG. 1A , according to a preferred embodiment of the present invention; 
         FIG. 9D  is a side elevation view illustrating an exemplary embodiment of a socket of the restricted ball and socket joint for headset ear cup of  FIG. 1A , according to a preferred embodiment of the present invention; 
         FIG. 10A  is a perspective cutaway view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup of  FIG. 1A , according to a preferred embodiment of the present invention; 
         FIG. 10B  is a side elevation cross-sectional view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup of  FIG. 1A  in a first orientation, according to a preferred embodiment of the present invention; 
         FIG. 10C  is a side elevation cross-sectional view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup of  FIG. 1A  in a second orientation, according to a preferred embodiment of the present invention: 
         FIG. 10D  is a side elevation cross-sectional view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup of  FIG. 1A  in a third orientation, according to a preferred embodiment of the present invention; 
         FIG. 11A  is a perspective cutaway view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup of  FIG. 1A , according to a preferred embodiment of the present invention; 
         FIG. 11B  is a side elevation cross-sectional view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup of  FIG. 1A  in a first orientation, according to a preferred embodiment of the present invention; 
         FIG. 11C  is a side elevation cross-sectional view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup of  FIG. 1A  in a second orientation, according to a preferred embodiment of the present invention; 
         FIG. 11D  is a side elevation cross-sectional view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup of  FIG. 1A  in a third orientation, according to a preferred embodiment of the present invention; 
         FIG. 12A  is a front elevation view illustrating an exemplary embodiment of a socket of the restricted ball and socket joint for headset ear cup of  FIG. 1A , according to a preferred embodiment of the present invention; 
         FIG. 12B  is a side cross-sectional view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup of  FIG. 1A , according to a preferred embodiment of the present invention. 
         FIG. 13A  is a side elevation cross-sectional view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup of  FIG. 1A  in a first ball extraction step, according to a preferred embodiment of the present invention; 
         FIG. 13B  is a side elevation cross-sectional view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup of  FIG. 1A  in a second ball extraction step, according to a preferred embodiment of the present invention; 
         FIG. 13C  is a side elevation cross-sectional view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup of  FIG. 1A  in a third ball extraction step, according to a preferred embodiment of the present invention; 
         FIG. 14A  is a side elevation cross-sectional view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup of  FIG. 1A  in a first ball extraction step, according to a preferred embodiment of the present invention; 
         FIG. 14B  is a side elevation cross-sectional view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup of  FIG. 1A  in a second ball extraction step, according to a preferred embodiment of the present invention; 
         FIG. 14C  is a side elevation cross-sectional view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup of  FIG. 1A  in a third ball extraction step, according to a preferred embodiment of the present invention; 
         FIG. 15A  is a side elevation cross-sectional view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup of  FIG. 1A  in a first ball resisting step, according to a preferred embodiment of the present invention; 
         FIG. 15B  is a side elevation cross-sectional view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup of  FIG. 1A  in a second ball resisting step, according to a preferred embodiment of the present invention; 
         FIG. 16  is a perspective view illustrating an exemplary embodiment of a ball of the restricted ball and socket joint for headset ear cup of  FIG. 1A  integral to a headset side piece, according to a preferred embodiment of the present invention; 
         FIG. 17  is a perspective view illustrating an exemplary embodiment of an ear cup having a socket of the restricted ball and socket joint for headset ear cup of  FIG. 1A , according to a preferred embodiment of the present invention; 
         FIG. 18  is a perspective view illustrating an exemplary embodiment of an irregular ball of the restricted ball and socket joint for headset ear cup of  FIG. 1A  integral to a helmet side piece, according to a preferred embodiment of the present invention; 
         FIG. 19  is a front elevation view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup of  FIG. 1A  used to form a headset, according to a preferred embodiment of the present invention; 
         FIG. 20  is a top plan view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup of  FIG. 1A  used to form a headset, according to a preferred embodiment of the present invention; 
         FIG. 21  is a side elevation view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup of  FIG. 1A  used to form a headset in a first configuration, according to a preferred embodiment of the present invention; 
         FIG. 22  is a side elevation view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup of  FIG. 1A  used to form a headset in a second configuration, according to a preferred embodiment of the present invention; 
         FIG. 23  is a side elevation view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup of  FIG. 1A  used to form a helmet headset, according to a preferred embodiment of the present invention; 
         FIG. 24  is a front elevation view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup of  FIG. 1A  used to form a helmet headset, according to a preferred embodiment of the present invention; 
         FIG. 25  is a perspective view illustrating an exemplary embodiment of an irregular ball of the restricted ball and socket joint for headset ear cup of  FIG. 1A  integrated into a headset in a first configuration, according to a preferred embodiment of the present invention; 
         FIG. 26  is a perspective view illustrating an exemplary embodiment of an irregular ball of the restricted ball and socket joint for headset ear cup of  FIG. 1A  integrated into a helmet headset, according to a preferred embodiment of the present invention; 
         FIG. 27  is a perspective view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup of  FIG. 1A  integrated into a headset in a second configuration, according to a preferred embodiment of the present invention; 
         FIG. 28  is a perspective partially exploded view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup of  FIG. 17 , according to a preferred embodiment of the present invention; and 
         FIG. 29  is a perspective view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup of  FIG. 19 , according to a preferred embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As used and defined herein, the term “integral” means “of one piece with or, in an additional embodiment, assembled with”. 
       FIG. 1A  is a perspective view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup  100 , according to a preferred embodiment of the present invention. Irregular ball  118  is sized and shaped to be inserted into socket  120 . Irregular ball  118  has a bulb  102  that has four axial grooves  112  (one of two visible of four labeled) circumferentially dispersed at even intervals and a stem  104 , which will typically extend between the bulb  102  and another device (not shown in this view) which is integral (preferably of one piece) with the stem  104 . Between grooves  112  on the bulb  102 , a semi-spherical section  122  extends axially from the stem  104  to a truncated conical section  126 . Irregular ball  118  is preferably made of a hard plastic with some resilience and is preferably made by injection molding. In various other embodiments, other materials and forming methods may be used. 
     Socket  120  includes support panel  108  having an opening  114  surrounded by a beveled ring  116 . Preferably, socket  120  is integral with support panel  108 . Interior to the beveled ring  116  is a concentric and oppositely beveled section  128  extending from the beveled ring  116  to inner cylindrical section  130 . Extending across the oppositely beveled section  128  and the inner cylindrical section  130  in four places (two visible) are ridges  110  (one of two visible labeled) which align with grooves  112  during insertion of ball  118  and during operation of the restricted ball and socket joint for headset ear cup  100 . The exterior of socket  120  has an outer cylindrical section  124  that is not coextensive with inner cylindrical section  130 . An external semi-spherical section  106  extends in the negative Z-axis direction (see  FIG. 1B ) from outer cylindrical section  124  to close the back of the socket  120 . External semi-spherical section  106  has an interior concentric and coextensive inner semi-spherical section  132 . 
     Panel  108  is shown as a rectangular solid but the invention is not so limited: panel  108  may be of any shape adequate to provide support around opening  114 . In a preferred embodiment, the entire socket  120  and panel  108  is formed of a single piece, preferably of injection molded plastic. 
       FIG. 1B  is a perspective view illustrating an exemplary embodiment of the socket  120  of the restricted ball and socket joint for headset ear cup  100 , according to a preferred embodiment of the present invention. The X, Y, and Z axes which will be referenced throughout this specification and in the claims are shown in relation to socket  120 . The origin is generally at the center of rotation of the irregular ball  118 , when installed, but the axes are shown outside the socket  120  for simplicity of the drawing. The axes are lettered on their positive ends. The Z-axis is along the central axis of radial symmetry of the beveled ring  116 , oppositely beveled section  128 , and the inner cylindrical section  130 . The alignment of ridges  110  with grooves  112  prevents the ball  118  from rotating about the Z-axis when the irregular ball  118  is installed in socket  120 . 
       FIG. 2  is a front elevation view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A  in a first exemplary configuration, according to a preferred embodiment of the present invention. Irregular ball  118  is shown installed in socket  120  and rotated minus twenty degrees about the X-axis, minus twenty degrees about the Y-axis, and zero degrees about the Z-axis. Rotation about X and Y axes are preferably restricted to plus and minus twenty degrees, as the present inventors have found that these limits comfortably accommodate the wide variety of head shapes among users. In various additional embodiments, other limits may be used. 
       FIG. 3  is a front elevation view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A  in a second exemplary configuration, according to a preferred embodiment of the present invention. Irregular ball  118  is shown installed in socket  120  and rotated minus twenty degrees about the X-axis, twenty degrees about the Y-axis, and zero degrees about the Z-axis. The cases shown in  FIGS. 2-5  are limiting cases, and positions resulting from rotations within the plus and minus twenty degrees restrictions are both possible and more typical in actual use. 
       FIG. 4  is a front elevation view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A  in a third exemplary configuration, according to a preferred embodiment of the present invention. Irregular ball  118  is shown installed in socket  120  and rotated twenty degrees about the X-axis, twenty degrees about the Y-axis, and zero degrees about the Z-axis. 
       FIG. 5  is a front elevation view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A  in a fourth exemplary configuration, according to a preferred embodiment of the present invention. Irregular ball  118  is shown installed in socket  120  and rotated twenty degrees about the X-axis, minus twenty degrees about the Y-axis, and zero degrees about the Z-axis. 
       FIG. 6  is a perspective view illustrating an exemplary embodiment of the irregular ball  118  of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A , according to a preferred embodiment of the present invention. Semi-spherical end piece  604  extends from truncated conical section  126 . Each groove  112  has a horizontal surface  608  and a vertical surface  606 . The stem  104  is illustrated as a cylindrical solid, but the invention is not so limited. Stem  102  is preferably molded as one piece with an object, such as a headset side piece  1600  (see  FIG. 16 ) or a helmet mounted side piece  1800 , and any shape or extent that is functional for such purposes is within the scope of the present invention. In addition, various other ball and socket applications in which rotations about the X and Y axes are limited and rotation about the Z-axis is prevented are within the scope of the invention, and any stem  102  shape or extent functional for those purposes is within the scope of the present invention as well. 
       FIG. 7  is a front elevation view illustrating an exemplary embodiment of the irregular ball  118  of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A , according to a preferred embodiment of the present invention. Semi-spherical end piece  604  moves slidingly and rotationally along the inner semi-spherical section  132 . Grooves  112  have perpendicular surfaces  606  and  608 . 
       FIG. 8  is a front elevation view illustrating an exemplary embodiment of the irregular ball  118  of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A , according to a preferred embodiment of the present invention. Semi-spherical end piece  604  can be most clearly seen in this view. The largest diameter of irregular ball  118  is within the semi-spherical section  122 . The truncated conical section  126  can also be most clearly seen in this view. Truncated conical section  126  tapers from the semi-spherical section  122  to the semi-spherical end piece  604 . 
       FIG. 9A  is a perspective view illustrating an exemplary embodiment of a socket  120  of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A , according to a preferred embodiment of the present invention. Ridges  110  are tapered from the boundary between oppositely beveled section  128  and inner cylindrical section  130  to both the inner semi-spherical section  132  and, oppositely, to the beveled ring  116 . 
       FIG. 9B  is a front elevation view illustrating an exemplary embodiment of a socket  120  of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A , according to a preferred embodiment of the present invention. Ridges  110  are slightly truncated at the boundary between the beveled ring  116  and the oppositely beveled section  128 , as will be discusses in more detail in regard to  FIG. 12 . 
       FIG. 9C  is a side elevation view illustrating an exemplary embodiment of a socket  1200  of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A , according to a preferred embodiment of the present invention. The dual taper of ridges  110  and the slight truncation of ridges  110  can be most clearly seen in this view. Inner semi-spherical section  132  has an inner semi-spherical surface  902 , which is preferably a low-friction surface. 
       FIG. 9D  is a side elevation view illustrating an exemplary embodiment of a socket  120  of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A , according to a preferred embodiment of the present invention. The inner cylindrical surface  904  of the inner cylindrical section  130  need not be a low-friction surface, as will be seen in discussion below. The retaining surface  906  of oppositely beveled section  128  is preferably a low-friction surface, as removal of the irregular ball  118  from the socket  120  requires sliding on retaining surface  906  and deformation of the ridge between the beveled ring  116  and the oppositely beveled section  128 . 
       FIG. 10A  is a perspective cutaway view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A , according to a preferred embodiment of the present invention. The maximum diameter of semi-spherical section  122  is located behind the ridge between the beveled ring  116  and the oppositely beveled section  128  and so irregular ball  118  is retained by the ridge between the beveled ring  116  and the oppositely beveled section  128 . The surface of semi-spherical section  122  engages a portion of inner cylindrical surface  904 . Semi-spherical end piece  604  slidingly engages inner semi-spherical surface  902  of inner semi-spherical section  132 . 
       FIG. 10B  is a side elevation cross-sectional view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A  in a first orientation, according to a preferred embodiment of the present invention. The longitudinal axis  1002  of the irregular ball  118  is coincident with the Z-axis, making an angle α=ninety degrees with the Y-axis. 
       FIG. 10C  is a side elevation cross-sectional view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A  in a second orientation, according to a preferred embodiment of the present invention. The longitudinal axis  1002  of the irregular ball  118  is rotated a negative twenty degrees about the X-axis, making an angle β=seventy degrees with the Y-axis. Oppositely beveled section  128  of irregular ball  118  engages retaining surface  906  of socket  120 . Semi-spherical end piece  604  of irregular ball  118  engages inner semi-spherical surface  902  of socket  120 . Truncated conical section  126  engages inner cylindrical surface  904 , restricting further negative rotation about the X axis. 
       FIG. 10D  is a side elevation cross-sectional view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A  in a third orientation, according to a preferred embodiment of the present invention. The longitudinal axis  1002  of the irregular ball  118  is rotated twenty degrees about the X-axis, making an angle γ=one hundred and ten degrees with the Y-axis. Oppositely beveled section  128  of irregular ball  118  engages retaining surface  906  of socket  120 . Semi-spherical end piece  604  of irregular ball  118  engages inner semi-spherical surface  902  of socket  120 . Truncated conical section  126  engages inner cylindrical surface  904 , restricting further positive rotation about the X axis. 
       FIG. 11A  is a perspective cutaway view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A , according to a preferred embodiment of the present invention. Irregular ball  118  is shown without rotation within socket  118 . Semi-spherical end piece  604  of irregular ball  118  slidingly and rotationally engages inner semi-spherical surface  902  of socket  120 . Truncated conical section  126  of irregular ball  118  engages inner cylindrical surface  904  of socket  120 . Semi-spherical section  122  of irregular ball  118  engages retaining surface  906  of socket  120 . 
       FIG. 11B  is a side elevation cross-sectional view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A  in a first orientation, according to a preferred embodiment of the present invention. The longitudinal axis  1002  of the irregular ball  118  is coincident with the Z-axis, making an angle α=ninety degrees with the X-axis. As sections  126 ,  128 , and semi-spherical end piece  604  are solids of rotation, and as socket inner surfaces  902 ,  904 , and  906  are all surfaces of rotation, the engagement of sections  126 ,  128 , and semi-spherical end piece  604  of irregular ball  118  with surfaces  902 ,  904 , and  906  of socket  120 , are similar to those for  FIG. 10B , except for a rotation about the Y-axis in this case. 
       FIG. 11C  is a side elevation cross-sectional view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A  in a second orientation, according to a preferred embodiment of the present invention. The longitudinal axis  1002  of the irregular ball  118  is rotated twenty degrees about the Y-axis, making an angle β=seventy degrees with the X-axis. As sections  126 ,  128 , and semi-spherical end piece  604  are solids of rotation, and as socket inner surfaces  902 ,  904 , and  906  are all surfaces of rotation, the engagement of sections  126 ,  128 , and semi-spherical end piece  604  of irregular ball  118  with surfaces  902 ,  904 , and  906  of socket  120 , are similar to those for  FIG. 10C , except for a rotation about the Y-axis in this case. 
       FIG. 11D  is a side elevation cross-sectional view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A  in a third orientation, according to a preferred embodiment of the present invention. The longitudinal axis  1002  of the irregular ball  118  is rotated twenty degrees about the Y-axis, making an angle γ=one hundred and ten degrees with the X-axis. As sections  126 ,  128 , and semi-spherical end piece  604  are solids of rotation, and as socket inner surfaces  902 ,  904 , and  906  are all surfaces of rotation, the engagement of sections  126 ,  128 , and semi-spherical end piece  604  of irregular ball  118  with surfaces  902 ,  904 , and  906  of socket  120 , are similar to those for  FIG. 10D , except for a rotation about the Y-axis in this case. 
       FIG. 12A  is a front elevation view illustrating an exemplary embodiment of a socket  120  of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A , according to a preferred embodiment of the present invention.  FIG. 12  best shows the truncation  1202  (one of four labeled) of the ridges  110  and the clearances  1204  (one of eight labeled) between the right-angled grooves  112  and the acutely angled ridges  110 . 
       FIG. 12B  is a side cross-sectional view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup of  FIG. 1A , according to a preferred embodiment of the present invention. Angle δ between inner cylindrical surface  904  of socket  120  and truncated conical section  126  determines the maximum rotation possible about axes that are orthogonal to the Z-axis. When irregular ball  118  is rotated until truncated conical section  126  abuts inner cylindrical surface  904 , further rotation is blocked by the abutment. 
       FIG. 13A  is a side elevation cross-sectional view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A  in a first ball extraction step, according to a preferred embodiment of the present invention. Retaining surface  906  of oppositely beveled section  128  of socket  120  engages semi-spherical section  122  of irregular ball  118  as Z-axis linear force  1302  urges axially-oriented irregular ball  118  from socket  120 . Z-axis linear force  1302  may be the entire force or a dominant Z-axis component of an off-Z-axis force. 
       FIG. 13B  is a side elevation cross-sectional view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A  in a second ball extraction step, according to a preferred embodiment of the present invention. Retaining surface  906  of oppositely beveled section  128  of socket  120  deforms and allows semi-spherical section  122  of irregular ball  118  to slide outward as Z-axis linear force  1302  urges Z-axially-oriented irregular ball  118  from socket  120 . Semi-spherical end piece  604  has disengaged from inner semi-spherical section  132 . 
       FIG. 13C  is a side elevation cross-sectional view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A  in a third ball extraction step, according to a preferred embodiment of the present invention. Z-axis-oriented Irregular ball  118  is removed from socket  120  by Z-axis linear force  1302 . 
       FIG. 14A  is a side elevation cross-sectional view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A  in a first ball extraction step, according to a preferred embodiment of the present invention. Retaining surface  906  of oppositely beveled section  128  of socket  120  engages semi-spherical section  122  of angularly-oriented irregular ball  118  as axial linear force  1402  urges angularly-oriented irregular ball  118  from socket  120 . 
       FIG. 14B  is a side elevation cross-sectional view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A  in a second ball extraction step, according to a preferred embodiment of the present invention. Retaining surface  906  of oppositely beveled section  128  of socket  120  deforms and allows semi-spherical section  122  of angularly-oriented irregular ball  118  to slide outward as axial linear force  1402  urges angularly-oriented irregular ball  118  from socket  120 . Semi-spherical end piece  604  has disengaged from inner semi-spherical section  132 . 
       FIG. 14C  is a side elevation cross-sectional view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A  in a third ball extraction step, according to a preferred embodiment of the present invention. Angularly-oriented irregular ball  118  is removed from socket  120  by axial linear force  1402 . The teaching of  FIGS. 13A-14D  is that an axial linear force  1302 ,  1402  can be used to remove irregular ball  118  from socket  120  regardless of the angular orientation of ball  118 . Where the angle of the axis of irregular ball  118  is less than twenty degrees off the Z-axis, then the axial linear force  1302 ,  1402  may be a dominant component of an off-axis force. 
       FIG. 15A  is a side elevation cross-sectional view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A  in a first ball resisting step, according to a preferred embodiment of the present invention. Torque  1502  causes truncated conical section  126  of irregular ball  118  to abut and bind inner cylindrical surface  904  of socket  120 , preventing further rotation of irregular ball  118  and preventing irregular ball  118  from being extracted from socket  120  by a torque  1502 . It will be clear to those of skill in the art, enlightened by the present disclosure, that the plane in which the torque  1502  acts is irrelevant to the result. 
       FIG. 15B  is a side elevation cross-sectional view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A  in a second ball resisting step, according to a preferred embodiment of the present invention. Linear off-axial force  1504  has an inward Z-axis component, relative to the socket  120 , and a torque component, and so produces the same binding between truncated conical section  126  of irregular ball  118  and inner cylindrical surface  904  of socket  120 , preventing further rotation of irregular ball  118  and preventing irregular ball  118  from being extracted from socket  120  by an off-axis force  1504 . The teaching of  FIGS. 13A to 15B  is that the irregular ball  118  successfully resists removal from the socket  120  except in response to a linear Z-axis force  1302  or  1402 . 
       FIG. 16  is a perspective view illustrating an exemplary embodiment  1600  of an irregular ball  118  of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A  integral to a headset side piece  1626 , according to a preferred embodiment of the present invention. Headset side piece  1626  is one of two headset side pieces  1626  that are used on opposing sides of a headset  1900  (see  FIG. 19 ) and to which ear cups  1700  and  1908  (see  FIG. 19 ) are attached, respectively, via restricted ball and socket joints for headset ear cup  100 . Irregular ball  118  is shown with preferred cup end  1602  in semi-spherical end piece  604 . Irregular ball  118  is fixed to headset side piece  1626  in a predetermined orientation, preferably with the groove  112  surfaces  608  and  606  horizontal and vertical, respectively, when headset side piece  1626  is in operational position. That is, with grooves  112  at forty-five degree angles from the long axis of the headset side piece  1626 . Headset side piece  1626  has a receiver  1604  for an adjustment band  1902  (see  FIG. 19 ), for adjusting the headset  1900  to a comfortable fit. Headset side piece  1626  is preferably made of a hard plastic with some small resilience. Headset side piece  1626  with irregular ball  118  is preferably made of one piece. 
       FIG. 17  is a perspective view illustrating an exemplary embodiment of an ear cup having a socket of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A , according to a preferred embodiment of the present invention. Ear cup  1700  is sized and shaped to cover a human ear. Considerable variation as to shape is comprehended within the present invention, within the functional limitation that the ear cup  1700  covers a human ear and supports the electronics needed for operation. Ear cup  1700  has an outer shell  1720  that includes a bottom panel  1706 , an upper panel,  1702 , and a socket  120 . Bottom panel  1706  supports internal electronics (not shown) and top panel  1702 . Top panel  1702  supports a push-to-talk (PTT) button  1710 , selector switches  1712  and  1714 , DC power jack  1716 , and fit-detection and/or noise cancellation external microphone  1720 , power button  1718 , and head strap attachment slot  1708 . Socket  120  has a round panel  108  but otherwise conforms to the previous figures for socket  120 . Panel  108  may be arcuate. A foam ring  1704  is attached to the edge of shell  1722  and forms the interface between the shell  1722  and the user&#39;s head. Foam ring  1704  is preferably closed cell foam and has a weather-resistant covering. 
       FIG. 18  is a perspective view illustrating an exemplary embodiment of an irregular ball  118  of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A  integral to a helmet headset side piece  1800 , according to a preferred embodiment of the present invention. Helmet headset side piece  1800  is one of two helmet headset side pieces  1800  that are used in opposing sides of a helmet headset  2300  (see  FIG. 24 ) and to which ear cups  1700  and  1908  (see  FIG. 24 ) are attached, respectively, via restricted ball and socket joints for headset ear cup  100 . Irregular ball  118  is shown with preferred cup end  1602  in semi-spherical end piece  604 . Irregular ball  118  is fixed to helmet headset side piece body  1802  in a predetermined orientation, preferably with the groove  112  surfaces  608  and  606  horizontal and vertical, respectively, when headset side piece  1800  is in operational position. That is, with grooves  112  at forty-five degree angles from the long axis of the helmet headset side piece body  1802 . Helmet headset side piece  1800  has a receiver  1804  for a helmet attachment band  2308  (see  FIG. 24 ), and a coupling  1806  for securing the helmet headset side piece  1800  to the helmet attachment band  2308  (see  FIG. 24 ). Helmet headset side piece  1800  is preferably made of a hard plastic with some small resilience. Helmet headset side piece  1800  with irregular ball  118  is preferably made of one piece. 
       FIG. 19  is a front elevation view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A  used to form a headset  1900 , according to a preferred embodiment of the present invention. Headset  1900  includes ear cup  1700 , ear cup  1908  and left and right headset side pieces  1600  coupled to ear cups  1700  and  1908  via restricted ball and socket joints for headset ear cups  100 . Left and right headset side pieces  1600  are adjustably connected by adjustment band  1902 , which is supported by head band  1904  and cushions  1906 . Head band  1904  is preferably a resilient material compatible with contact with the user&#39;s head. Ear cup  1908  is substantially the same structure as ear cup  1700 , with or without redundant controls, preferably has a mirror-image shape, and supports a noise-cancelling microphone  1912  mounted on boom  1910  extending from fitting  1914  on the shell of ear cup  1908 . 
     The restricted ball and socket joints for headset ear cups  100  enable free movement of the ear cups  1700  and  1908  within plus or minus twenty degrees top-to-bottom and front-to-back, but do not allow the left and right headset side pieces  1600  and adjustment band  1902  to rotate with respect to the ear cups  1700  and  1908 . The restricted movement of the restricted ball and socket joints for headset ear cups  100  enables the headset  1900  to comfortable and functionally adapt to a wide variety of head shapes and sizes, while preventing fit problems arising from rotation of the left and right headset side pieces  1600  and adjustment band  1902  relative to ear cups  1700  and  1908 . 
       FIG. 20  is a top plan view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A  used to form a headset  1900 , according to a preferred embodiment of the present invention. The headband  1904  preferably supports most or all of the weight of the headset  1900 , with friction between the foam rings  1704  and the user&#39;s head making only a minor contribution, if any. 
       FIG. 21  is a side elevation view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A  used to form a headset  1900  in a first configuration, according to a preferred embodiment of the present invention. Over-the-head portion  1600 ,  1902 ,  1600  cannot rotate forward or backward relative to ear cups  1700  and  1908  due to the restricted ball and socket joints for headset ear cups  100 . 
       FIG. 22  is a side elevation view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A  used to form a headset  1900  in a second configuration  2200 , according to a preferred embodiment of the present invention. Over-the-head portion  1600 ,  1902 ,  1600  cannot rotate forward or backward relative to ear cups  1700  and  1908  due to the restricted ball and socket joints for headset ear cups  100 . In order to transition from the first configuration  1900  shown in  FIG. 21  to the second configuration  2200  shown in  FIG. 22 , both of the restricted ball and socket joints for headset ear cups  100  must be disconnected (see  FIGS. 13A to 15B ), reoriented to the ear cups  1700  and  1908 , and re-connected in the second configuration  2200 . Between the first and second configurations  1900  and  2200 , respectively, there are no intermediate configurations as grooves  112  of irregular ball  118  only align to ridges  110  of socket  120  at ninety degree intervals. The second configuration  2200  shown in  FIG. 22  preferably includes a head strap  2702 , as shown in  FIG. 27 , for supporting the weight of the headset  1900  in configuration  2200 . 
       FIG. 23  is a side elevation view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A  used to form a helmet headset  2300 , according to a preferred embodiment of the present invention. Helmet  2302  has a plurality of connection points  2304 , one of which, on each side of helmet  2302 , is aligned to the wearer&#39;s ear. A coupling  2310  is inserted into each ear-aligned connection point  2304  which couples to a bent support  2308  which connects to helmet mounted side piece  1800  that includes irregular ball  118 . Irregular ball  118  is inserted into socket  120  of ear cup  2306  to allow restricted rotation top-to-bottom and front-to-back to achieve a good fit regardless of head shape or size. 
       FIG. 24  is a front elevation view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A  used to form a helmet headset  2300 , according to a preferred embodiment of the present invention. Bent support  2308  and coupling  2304  can be more clearly seen in this view. 
       FIG. 25  is a perspective view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A  integrated into a headset  1900  in a first configuration, according to a preferred embodiment of the present invention. The invention does not require that the user is bald. 
       FIG. 26  is a perspective view illustrating an exemplary embodiment of a ball of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A  integrated into a helmet headset, according to a preferred embodiment of the present invention. Helmets  2302  of various shapes and styles may be adapted to support the helmet headset  2300 . 
       FIG. 27  is a perspective view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup  100  of  FIG. 1A  integrated into a headset in a second configuration, according to a preferred embodiment of the present invention. Head strap  2702  is preferably made of a comfortable fabric. 
       FIG. 28  is a perspective partially exploded view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup  1700  of  FIG. 17 , according to a preferred embodiment of the present invention. This view more clearly shows the boundary between bottom panel  1706  and top panel  1702 . 
       FIG. 29  is a perspective view illustrating an exemplary embodiment of the restricted ball and socket joint for headset ear cup  1908  of  FIG. 19 , according to a preferred embodiment of the present invention. Shell  2902  differs from shell  1702  in that it is left-handed and accommodates boom microphone  1910 , volume up button  2906 , volume down button  2906 , and menu/answer button  2908 . 
     The embodiments described above are merely exemplary. Such examples are limited only by the claims below in light of the specification above. Those of skill in the art, enlightened by the present disclosure, will understand the variety of ways that restricted ball and socket joints may be used to ensure useful limitations in the motion of ball and socket joints.