Abstract:
An improved scissor-type clamp includes two opposing clam shell type members, one male and one female, that pivot together, are biased outwardly by coil springs and are held together by a thumbscrew. Embodiments feature rectangular and tapered opposed clam shell portions and one embodiment includes identical clam shell members.

Description:
This invention relates to a clamp with opposed ball receiving ends for clamping a movable object in changeable fixed relation to a fixed base and, more particularly, to a scissor type clamp having opposed ball receiving ends. 
   BACKGROUND OF THE INVENTION 
   Adjustable mountings for cathode ray tubes (CRT), light emitting diode (LED), and/or plasma screens and other monitors are quite popular as desktop computers have become tower designs built to be positioned out of sight under a worker&#39;s desk. The mounting may be fixedly positioned at one end on a desk, on a wood or metal stand positionable on the desk, or on a wall or other structure. 
   One such clamp presently utilized to adjustably mount a pair of ball mounting ends thereto is found at U.S. Pat. No. 5,845,885 issued to Carnavalli Dec. 8, 1998. The clamp disclosed in Carnavalli has opposed double clam shell type ends held together by both being pivotally mounted to a central bolt having a handle screw threaded onto one end thereof. With each of the centrally facing clamp halves, freely rotatable about the bolt axis and also axially movable depending upon the tightness of the handle on the bolt, the clamp tends to be somewhat unstable until the handle is fully tightened on the bolt clamping each of the clamp halves onto its respective ball mounting. 
   A need has developed for an improved double ended ball holding clamp having improved stability in its unclamped mode. 
   SUMMARY OF THE INVENTION 
   It is therefore an object of the present invention, generally stated, to provide a new and improved double opposed adjustable ball mounting clamp for use, among other mountings, for adjustably positioning a cathode ray tube or light emitting diode screen thereon. 
   Another object of the present invention is the provision of an improved double opposed ended ball mounting clamp having a scissor clamping feature. 
   The invention resides in a scissors type clamp with opposed ball receiving heads. The clamp comprises a pair of elongate complementary split arm members with each including hollow semi-ball shape ends facing a common plane. Each split arm member includes a pivotal mounting positioned substantially centrally between each of the semi-ball shape ends. The pivotal mounting on one of the pair of split arm members is complementary to a pivotal mounting on the other of the split arm members. The clamp further includes adjustable fastener means retained on each of the pair of complementary split arm members offset to a common side of the pivotal mounting for selectively adjusting the distance between complementary ends adjacent one another. 
   The invention further resides in a scissor clamp comprising a pair of substantially identical clamp members. Each such member includes opposed end portions with each such portion having a recess for providing about half an operative clamp with each such recess facing a common plane from opposing sides thereof and a central portion connecting the opposing portions and crossing the common plane. The central portion is offset to one side of the opposed end portions and includes pivot means through the central portion substantially on the common plane for providing operative pivotal mounting together of the pair of substantially identical clamp members. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The invention may best be understood from the following detailed description of currently preferred embodiments thereof taken in conjunction with the accompanying drawings, wherein like numerals refer to like parts, and in which: 
       FIG. 1  is a perspective view of a first embodiment of a scissor clamp, constructed in accordance with the present invention, for clamping a pair of ball shape mountings; 
       FIG. 2  is an exploded perspective view of the first embodiment of the scissor clamp of the present invention; 
       FIG. 3  is a detail perspective view of the first embodiment of the scissor clamp members shown in  FIG. 1 ; 
       FIG. 4  is a vertical cross sectional view of a second embodiment of the scissor clamp; 
       FIG. 5  is a cross sectional view taken substantially along line  5 - 5  of  FIG. 4   a    
       FIG. 6  is a cross sectional view taken substantially along line  6 - 6  of  FIG. 4   a;    
       FIG. 7  is a front elevational view of a female clamping member of the second embodiment; 
       FIG. 8  is a top plan view of the female clamping member shown in  FIG. 7 ; 
       FIG. 9  is a side elevational view of a male clamping member of the second embodiment; 
       FIG. 10  is a top plan view of the male clamping member shown in  FIG. 9 ; 
       FIG. 11  is a perspective view of a third embodiment of the present invention utilizing two identical scissor halves. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to  FIG. 1 , a first embodiment of a scissor type clamp, generally indicated at  20 , constructed in accordance with the present invention as shown most clearly in  FIG. 1 , receives a first ball-type socket mounting  21 , generally indicated at  21  at the bottom thereof, which is preferably mounted on a flat surface, such as a desk, wall, etc. (not shown) and a substantially identical second ball type socket mounting, generally shown in dotted line at  21 A, which is mounted as shown in  FIG. 1 , on the bottom of a CRT monitor, generally indicated at  22 . It should be noted that any item can be attached to the ball mounting  21 A retained by the clamp  20  of the invention. LCD, plasma and other flat panel displays may commonly be adjustably positioned by the scissors type clamp of the invention. 
   The clamp  20  of the invention includes a pair of scissor-like members, generally indicated at  23  and  24 . The only other externally viewable part of the scissor clamp of the invention  20  is a thumb screw  25  that holds the members together adjacent one end of the scissor clamp  20 . The scissor clamp of the invention is preferably made of die cast metal, but can be made of molded plastic, ceramic material, or the like as long as the material is of sufficient strength to support an intended load. 
   Referring to  FIGS. 2 and 3 , female scissor part  23  includes opposing end sections  27  and  28  with a pair of spaced apart offset web sections  29 ,  30  connecting the opposed end sections. The central offset walls  29  and  30  each include a female trunion receiving mounting  31  (only one shown in  FIG. 2 )  32  shown in dotted line. Each of the opposed ends  27  and  28  of the female scissor member  23  are hollow with open areas facing a common plane running through the trunion receiving mountings  31 ,  32 . 
   Adjacent each of the opposed ends  27 ,  28  of scissor member  23  are positioned semicircular recesses  35 ,  36  that form a boundary of the generally curved end walls  37 ,  38 , respectively. Each of these recesses forms one half of the means for retaining the scissor clamp on the ball type mountings  21 ,  21 A. A hollow cylindrical annular wall  40  is mounted in the interior of end section  27  extends to the interior of the clamp, and is internally threaded to receive the threaded end of thumb screw  25 . A similar cylindrical post (not shown) is mounted on the inner wall of end section  27  extends internally similarly to the hollow cylindrical wall  40  to receive one end of a spiral spring  41 . Cylindrical wall  40  not only receives the threaded end  25 A of thumb screw  25 , but also receives and retains a spiral spring  42  around the outside thereof. 
   A complementary second scissor member, generally indicated at  24 , also includes a pair of opposing hollow end sections  44 ,  45 . In this member they are joined together by an offset single central web  46  in the hollow interior thereof. End section  44  also includes a generally cylindrical post  47  which is adapted to receive and retain around the outside thereof one end of the spiral spring  41 . Outwardly adjacent the post  47  is a semicircular recess  48  that is complementary to recess  35  on end section  27  of first scissor member  23 . At the opposite end of second scissor member  24 , and the distal portion of end section  25 , is a fourth semicircular recess  50  that is complementary to recess  36  on end section  28  on first scissor member  23 . Inwardly thereadjacent on the outer wall  51  of end section  24  is a circular aperture  52 . The threaded end  25 A of thumbscrew  25  extends through aperture  52 . The one end of spiral spring  42  is retained by the inside surface of the backside  51  around aperture  52 . 
   The central offset portion  46  or web between the end sections  44  and  45  of second scissor member  24  has positioned centrally on the opposite sides thereof, a pair of trunion mountings (only one shown)  54  which mount respectively in the female trunion receiving portions  31 ,  32 , of the first scissor member  23 . To provide a pivot point for the scissor members to interact. 
   In operation the assembly is put together by rotating one of the opposed ends of second scissor member  24  ninety degrees and moving one of the ends  44  or  45  through the central aperture  33  defined between the opposed offset halves  29 ,  30 . After the end is moved therethrough, the second scissor member is again rotated in a reverse direction to that previously to enable the trunion mountings  54  to slide into the trunion mounting receiving recesses  31 ,  32  in the central offset portion of the first scissor member  23 . 
   With the scissor members pivotally mounted together, the spiral springs  41  and  42  may be compressed and mounted on the posts  40 ,  47  and the thumb screw  25  may be inserted through the aperture  52  and threaded onto the interior of hollow post  40  to close the scissor clamp or allow it to be opened. 
   Referring to  FIG. 3 , the first and second scissor members  23 ,  24  are shown in their assembled positioned with the semicircular recesses  50  and  36  for capturing and retaining the ball-type mountings  21 ,  21   a  are shown in more detail. 
   Referring to  FIGS. 4-10 , a second embodiment of the preferred invention is shown generally at  60 . This second embodiment  60  is constructed similarly to the first embodiment  20  with the exception that the outer surfaces of the opposed ends are clam shell shaped and the center offset portions form a more narrow waist that that shown in the first embodiment  20 . 
   The clam shell type scissor clamp  60  of the second embodiment includes first scissor member  61 , and second opposing scissor member, generally indicated at  62 . As shown most clearly in  FIGS. 5 and 6 , the outer surface of the first and second scissor member opposed ends are more rounded or semicylindrical in shape than the outer surfaces of the opposed ends of first embodiment  20 . First scissor member  61 , similarly to first scissor member  23 , includes opposed end portions  63  and  64 , previously mentioned, that have semicircular wall with each including a semicylindrical shape recess  65 ,  66 , respectively. 
   Likewise, the opposed ends of second scissor member  62  include semispherical recesses  71  and  72 . As with the first embodiment  20 , the semicylindrical outer walls  63 ,  64  of first scissor member  61  and the semicylindrical outer walls  68 ,  69  of scissor member  61  both are hollow, with a narrowed waist section between the outer walls on each respective member. 
   With first scissor member  61  the narrowed waist portion is composed of a pair of opposed spaced apart web members  74 ,  75  ( FIG. 8 ) which are canted or offset as shown most clearly in  FIG. 7  such that the inner edge  63   a  of clam shell  63  and the inner edge  64   a  of clam shell  64  are parallel and lie on either side of a center line of the offset portion  75 . Centrally of each of the offset portions is a trunion mounting  76 ,  77  and an elongate recess  78 ,  79  that allows a pivot member, to be discussed in more detail below, to be mounted between those trunion mountings  76 ,  77 , respectively. The opposed offset central webs  74 ,  75  together with the bases  63   b ,  64   b  provide a very rigid central framework for the first scissor member  61  of the second embodiment. Additionally, first scissor member  61  of the second embodiment includes an aperture  73  through the semicircular wall  64 . 
   Referring to  FIGS. 7 and 8 , on the left side of the first scissor member  61  at the center of the outer wall is an aperture  82  that extends through the wall  63  to the interior thereof. On the right side of the inner surface of the outer wall  64  is a post  83  that extends into the hollow interior of the clam shell shaped outer wall. 
   Referring to  FIGS. 9 and 10 , a second scissor member  62  of the second embodiment is shown and described and includes similarly to the first scissor member, opposed clam shell outer walls  68  and  69  having semispherical recesses  71  and  72  positioned at the outer portions of each. As in the first scissor member  61 , the opposed clam shell outer wall  68  and  69  are hollow. Within the interior of the first clam shell portion  68 , a hollow, generally cylindrical wall  84  includes a threaded aperture  85  through the top thereof in which a second thumb screw  86  may be threadedly received ( FIG. 4 ). 
   On the hollow inside of clam shell portion  69  of second scissor member  62  is positioned a post  86  similar to post  83  of the first scissor member and positioned so as to be aligned therewith in spatial relation when the first scissor member and second scissor member are assembled. The threaded aperture  85  is positioned so as to be aligned with aperture  82  in the first scissor member in spatial relation thereto when the first and second scissor member  61  and  62  are mounted together. 
   Unlike the first scissor member  61 , the second scissor member  62  includes a single offset central web  87  that is offset in a direction opposite that of the offset web  75  of the first scissor embodiment such that the opposed edges  88  and  89  of clamshell portions  68  and  69  are on opposing sides of an axis centrally through the second scissor member  62  and through the offset portion  87 . Along this axis is positioned a pair of cylindrical trunions  91  and  92  which extend perpendicular to the central axis running parallel to surfaces  88  and  89 . 
   As with the first embodiment, trunions  91  and  92  are positioned so as to be fit into trunion mountings  76 ,  77 , respectively when the first and second scissor member  61 ,  62  are brought together. As with the first embodiment, the assembly of the scissor members is performed by rotating one clam shell of the second scissor member  62  ninety degrees and inserting same through the opening between members  74 ,  75  of the first scissor member  61 . After the clam shell is positioned therethrough, the member is reverse rotated 90 degrees and the trunions  91 ,  92  are positioned through trunion mounting recesses  78 ,  79  into their trunion mounting  76 ,  77 . 
   Coil springs  93 ,  94  ( FIG. 4 ) are positioned around the posts  83 ,  86  and around the thumbscrew  86 , respectively to maintain the opposed clam shell halves in an outwardly biased position, absent the threading of thumbscrew  86  in the threaded aperture  85 . 
   In operation, the ball type mountings  21 ,  21   a  shown in  FIG. 1  may be inserted in the hollow interior of the clam shells so as to extend outwardly through the space between the semispherical recesses  65 ,  71  and  72 ,  66 . Thereafter, the thumbscrew  86  is threaded into its threaded aperture, or tightened therein, until the ball type mountings are secured within the recesses. 
   The third embodiment  100  of the scissor clamp includes a pair of identical hollow cylindrical or clam shell shaped scissor member halves  101 - 101 , with each having opposing hollow clam shell portions  102 ,  103  therein separated by a double offset web  104 . Clam shell portion  102  includes a semispherical recess  105  adjacent the end thereof and an aperture  106  through an outer wall thereof. 
   Clam shell portion  103  includes a semicylindrical recess  107  adjacent the end thereof and a central hollow post  108  extending from the inner hollow surface thereof that includes a threaded aperture  109  centrally therein. The double offset central web  104  includes a central bore  111  therethrough. When a pair of the scissor members  101 - 101  are mounted together, the apertures  111 - 111  align so that a pivot pin  112  and a retaining clip  113  mounted adjacent the end of pivot pin  112  retain the two members in a pivotal scissors type mounting. 
   As in the previous embodiments, a pair of coil springs  114 - 114  are mounted between the hollow threaded posts  108  and the aperture  106  so as to allow a thumb screw  115  to be mounted through the aperture within the coil spring and be retained on the threaded interior  109  of the hollow cylindrical post  108 . In this embodiment, the inner surface of the clam shell portion  102  includes a slight ridge around the edge of aperture  106  on the interior thereof identified as  106   a  that provides a mounting for one end of the coil spring  114 . 
   Thus, a simplified version of the scissor clamp utilizing just a pair of a single, preferably molded scissor half members provides a less expensive means of utilizing a scissor clamp for variably mounting an external member, preferably a monitor, CRT, television or the like to an external surface. 
   While three differing embodiments of the present invention have been shown and described, it will be apparent to those skilled in the art that many changes and modifications may be made without departing from the true spirit and scope of the present invention. It is the intent of the appended claims to cover all such changes and modifications which fall within the true spirit and scope of the invention.