Patent Publication Number: US-7900882-B2

Title: Dual hook clamp

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of and claims priority to U.S. application Ser. No. 09/779,194, filed on Feb. 7, 2001 now U.S. Pat. No. 6,682,031, which claims the benefit of U.S. Provisional Application Serial No. 60/181,455 filed Feb. 10, 2000. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a clamp for holding a stage-mounted device relative to a stage support truss. More specifically, the present invention defines a hook clamp, which holds the weight and position of the stage-mounted device while it is being mounted to the support truss, and also has an electrical connector extending through the clamp. 
     BACKGROUND AND SUMMARY 
     Many stage-mounted devices require a stable base of support. Moving stage lights are often particularly sensitive to such requirements. Typically, moving lights are electronically controllable to move between various positions and to provide special effects. The position of a moving light, however, is accurate only when the system has a very stable base of support. Moreover, because of the lamp size, cooling requirements, and complicated electronics, these lamp devices can be very heavy. Many times such lights are mounted at the upper area of the stage, very high off the ground. 
     Many lamp clamps are known in the art. Some of the commonly used ones are described herein. A Cheeseborough clamp (U.S. terminology) or Scaff clamp (U.K. terminology) is shown in  FIG. 1 . The clamp  100  is shown in its open position in  FIG. 1 . The moving part  122  of the clamp pivots around pivot point  104  to form a closed clamp as shown in  FIG. 2  which closes around the supporting pole or pipe. The clamp can be tightened by tightening bolt  106  relative to bolt accepting mechanism  108 , which can be a slot or the like in a plate. The appropriate tightening reduces the size of the inner surfaces, to tighten the clamp and to maintain the lamp in position relative to pole  200 . 
     The inventors of the present invention recognized that this system is very difficult for the installers to use. One main reason is because the entire weight of the lamp must be supported by the installer while attaching the lamp to the pole  200 .  FIGS. 1 and 2  show these clamps in the open and closed position, respectively to demonstrate the installation. In order to install the lamp, the installer must hold lamp  110  while placing the open clamp  100  against pole  200  and while holding surface  120  of the open clamp against the supporting pole  200 . The clamp is hinged around pivot  104  to form a cylindrical inner area  205 , as shown in  FIG. 2 . Bolt  106  holds relative to bolt accepting element  108 . 
     In order for the lamp to be properly attached to the supporting pole  200 , therefore, the bolt  106  must be screwed into the accepting element  108  (e.g., a nut or a split holder). Alternately, a wing nut or like mechanism, on element  108  can be screwed into bolt  106 . In any of those cases, the installer must hold the weight of the lamp, which can be as heavy as 60 pounds, while holding the clamp closed and simultaneously screwing the nut into place. Moreover, even once the nut is screwed into place, the lamp is still not maintained in its proper position relative to the pole until the nut and screw  106 ,  108  are properly tightened. 
     These most-common kind of lamp clamps have been recognized by the inventors of the present invention to cause problems, making the lamps very difficult to install. 
     A second kind of mounting mechanism is shown in  FIG. 3 . The lamp  110  is connected to a folded piece of metal  300 , which includes vertically extending portions  302  and  304 , and a horizontal portion  306 . The inside surface  308  of clamp  300  is placed against the supporting pipe  200 . Since the metal  300  is formed of folded flattened metal sheets, the inside surface  308  touches the pole  200  only at tangent points between the flat surfaces and the round pipe, such as  310 . Rotation of lamp  110  relative to pole  200  is prevented by tightening set screw  312  against point of contact  314  on the pole  200 . 
     There are still problems with this system. Significantly, this system allows the weight of the lamp to be placed on the pole prior to tightening the set screw  312 . However, the lamp can still rotate relative to the pole, at least until the set screw is tightened against the pole. Moreover, this design tends to distort the roundness of the pole because of the large amount of force at the location  314  where the set screw  312  touches the pole. As can easily be seen, moreover, the system is inherently unbalanced. 
     A different, but similar kind of prior art clamp is shown in  FIG. 3A . That clamp includes the same basic structure as shown in  FIG. 3 . It includes the set screw  312  which presses against a portion of the support pole  200 . Ridges  350  and  352  provide extra friction to hold the lamp relative to the pole. 
     Power must also be applied to the lamp. Typically the power travels either along the pole or along a separate conduit, which is near the pole. The inventors of the present invention have recognized the inconveniences and difficulties, which often occur in getting the power to the lamp. 
     Since the lamps are very heavy, it is also important to ensure that the lamp does not fall from its position on the pole. Accidents can happen, for example, if a technician fails to properly secure the lamp to the pole, or if the securing mechanism fails. Such accidents risk both damage to very expensive equipment, as well as a serious threat to stage workers. One aspect of the present invention proposed a fail-safe mechanism for a lamp. 
     It is also desirable that the lamp mounting mechanism be versatile in its selection of mounting techniques. One particularly interesting mounting technique is a floor mounting. This technique uses a plate or other support base holding special flanges on the clamp. Those flanges position the lamp and clamp “upside down” relative to the position in which the lamp would be if pole mounted. 
     It is an object of the present invention to provide a clamp which allows flexibility and safety by special techniques which can be used individually or in combination. This is done according to the present invention by providing an element, which has interior surfaces defining an area which approximates in shape the outer surface of the supporting truss, over at least over half of the outer surface of the truss support. This ensures maximal frictional contact between the support and the clamp. This friction maintains the lamp in its proper position relative to the truss, even prior to frictional tightening. 
     A movable element tightens a tightening device into contact with the support element to further maintain the lamp in position. The inventor recognized that the combination of an inner surface approximating the outer surface of the support pole, and a design that allows hooking over the support pole produces a much easier-to-use system. 
     Structure is provided in the clamp that facilitates the channelling of power to the lamp. One aspect of this invention includes a special structure incorporated within the clamp which facilitates power routing to the lamp. This structure includes surfaces defining a special hole in a special location on the clamp. A special connector receives power and routes the power to a power conduit. That power conduit is routed around the rear of the connector through another hole and into the lamp. This aspect facilitates application of power to the lamp without the need to provide a separate external power conduit. 
     Another feature of the present invention uses a fail-safe mechanism, which allows a safety cable through the clamp and around the pole. A technician mounting the lamp can initially connect the safety cable to avoid the lamp falling or the like while it is being installed. 
     Another feature of the present clamp provides two separate mounting surfaces: a first surface which allows connection to a support pole such that the clamp is secured in a first orientation, and a second surface which allows connection in a way such that the clamp is secured in a second orientation, different than the first orientation. The preferred surfaces include pole mounting surface, mounting the lamp on the bottom of the clamp, and a floor mounting surface mounting the lamp on the top of the clamp. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other aspects of the invention will now be described in detail with reference to the accompanying drawings, wherein: 
         FIG. 1  shows a Cheeseborough clamp of the prior art in the open position; 
         FIG. 2  shows the Cheeseborough clamp in the closed position; 
         FIG. 3  shows another clamp of the prior art; 
         FIG. 3A  shows a modification of the  FIG. 3  clamp; 
         FIG. 4  shows a side view of the clamp of the present invention in the open position; 
         FIG. 5  shows the clamp of the present invention in the closed position; and 
         FIG. 6  shows an exploded view of the clamp of the present invention. 
         FIG. 7  shows an assembled view of the clamp of the present invention. 
         FIG. 8  shows a side view of the clamp and interface cable of the present invention. 
         FIGS. 9A and 9B  show an elevated view of the clamp and mounting bracket of the present invention. 
         FIG. 10  shows an elevated view of the clamp and mounting bracket of the present invention mated together. 
         FIG. 11  shows a dual clamp embodiment; 
         FIG. 12  shows a reverse view of the dual clamp embodiment; 
         FIG. 13  shows the calibration plate; 
         FIG. 14  shows a layout of multiple luminaries. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
       FIG. 4  shows a first embodiment of the invention, which includes lamp  110  connected to the hook clamp  400  of the present embodiment. More generally, any load could be attached to hook clamp  400 . Hook clamp  400  is adapted to surround a substantially cylindrical support  402  to hold the weight of lamp  110 . Support  402  is conventionally a pole, although it could be of any shape. 
     The hook clamp includes inner surfaces  404  which are substantially the same size and shape as the outer surface  406  of the support  402 . By this is meant that the inner surfaces are sized and shaped similarly to the support. The shapes are sufficiently similar that there is a maximal amount of friction between the clamp and support to keep the clamp in position even prior to tightening. This embodiment attaches to a cylindrical support element  402 , and surfaces  404  at least along a portion of the clamp are similarly cylindrical. The line  410  indicates a dividing line. Inner surfaces  404  above the dividing line  410  are cylindrical in shape and of substantially similar shape to the outer surface  406  of the support. The portions between lines  411  and  412  are also cylindrical. The pressure of outer surface  406  of pole  402  against inner surface  428  of hook portion  430  presses cylinder  402  into cylindrical surface area  422 —at least between lines  411  and  412 , and more preferably between lines  409  and  412 . The surface  414  preferably includes relatively flat surfaces against which the pole is pressed during the initial time while the hook portion  430  is being secured into position over the pole  402 . 
     The tongue  420  pivots around its pivot point  423 , and can be moved into a position where the inside surface  424  fictionally engages against the support member  402 . This final position is shown in  FIG. 5 , with the surface  424  abutting against the outer surface of the support  402 . The other surfaces  406  of the support which are above the line  410  also abut against the inner surfaces  404  of the internal cylindrical element. Inner surface  424  of the tongue is preferably concave and similar in shape to the outer surface of support  402 . 
     In operation, the user “opens” the tongue  420  by lowering it to its lowermost position shown in  FIG. 4 . The user first hooks the device over the support member  402 . The support member  402  comes in contact with surface  414 . The clamp can slide with the flat surface  414  against the pole. The clamp slides until the hooked end  430  is located above and hooked over the top support surface  406 . At that time, the outer surfaces  406  of support  402  contact inner surfaces  404  of the clamp  400 . The lamp  110  is preferably located at the center of gravity of the clamp, to minimize side-to-side torque on the clamp. The friction of the close fit between the inner surfaces of the clamp and the outer surfaces of the support pole therefore are preferably sufficient to keep the lamp steady and in position. 
     The tongue  420  is then lifted into position, placing the bolt  440  into a corresponding notch  442  to close the clamp as shown in  FIG. 5 . Notch  442  can be formed in hooked end portion  430  or in tongue  420 . When the bolt is tightened, it holds the inside surface  424  into close frictional contact with the support  406 . This tightens the clamp around the pole, so that the support is fictionally held by many similar-shaped surfaces. Since many surfaces of the pole are held, less tightening is necessary and hence there is less chance of distorting the pole shape. Preferably, many of the parts of the clamp are of similar shape to the outer surface of the pole. All portions above the line  410  are of similar shape, and preferably this is approximately 140° of the circle defined by the cylinder. Preferably all portions between the lines  411  and  412  also define arcs which are circular and which hence closely approximate the shape of the pole. The position from the left part of line  410  to the right part of line  412  preferably defines about 250° of the circle. An additional 30° or so also has similar shaped elements in the surface  424 . Accordingly, preferably 280° of the circle defined by the cylinder are substantially the same shape as the surface of the pole. This means that only 80° is not the same shape as the support pole. Thus 280/360, or approximately 75 percent, of the outer surface of the pole is preferably gripped by similar-shaped surfaces of the clamp. 
     The above-described first embodiment has the significant advantage of allowing frictional holding of the lamp even prior to tightening. This frictional holding, combined with the advantageous structure of the lamp hook of the present invention keeps the lamp hooked in place on the support pole. 
     A second embodiment of the present invention includes additional structure. 
       FIG. 6  shows an exploded view of the multiple parts making up the hook clamp of the second embodiment. It should be understood that these parts making up the exploded view are also the same parts, which exist in the first embodiment.  FIG. 7  shows the hook clamp fully assembled. 
     The hook clamp body is formed of two bent elements of sheet metal, including left member  600  and right member  602 . Each has a cutout area defining a cylindrical surface  404  and defining flat surface  414 . Members  600  and  602  are bolted to one another through a rear surface element  604 . Element  604  has inner surfaces  606  defining substantially a portion of a cylinder. The hook clamp is bolted together to form an element having left  600  and right pieces  602 , separated by the width of spacers  605 ,  611 . Spacer elements  605  and  611  are provided between the central element  606  and the respective end elements  602  in order to prevent the tongue  420  and bolt  440  from pinching between the sheet metal elements  600 ,  602 . 
     The rear surface element  604  also includes top and bottom split portions  610  and  612 . Each of the split portions includes a movable element therein which is pivoted about a pivot point. The “top” split element  610  includes inner surfaces allowing bolt  440  to pivot therein. Bolt  440  pivots about pivot axis  614  to be swung up and out of the way for attachment of the lamp. Bolt  440  is later pivoted into position for securing the tongue. Lower split portion  612  includes inner surfaces allowing tongue  420  to pivot relative thereto along the tongue axis  422 . 
     Tongue  420  also includes split portion  442  having surfaces  620  which are pressed against by corresponding surfaces  622  of the bolt. When the bolt  440  is tightened, the surfaces  622  press against the surfaces  620  to press tongue surfaces  424  closer to the rear surfaces  606 . This has the effect of reducing the internal surfaces defining the cylindrical grip of the clamp, to thereby press the hook clamp more tightly against the cylindrical support  402 . 
     The left and right pieces  600  and  602  include mounting holes  640  therein, preferably at a center of gravity of the clamp device. Mounting holes  640  receive screws for mounting the lamp  110 . 
     The inventors of the present invention further recognized that electrical connection to the lamp could be facilitated by providing a connector, which is a integral part of the lamp. This connector portion operates as shown and explained herein. 
     The rear mounting plate  650  includes special inner surfaces  652  defining a hole of the proper size to receive a speak-on type connector  654 . This connector is well known in the art, and is of the type typically used in the lighting industry. Of course, any suitable connector could be located in this position. The interface end  656  of the speak-on connector receives the power cable to provide power and/or control signals.  FIG. 7  shows the exit end  660  providing an output to interface cable  670 . A wiring end  672  of interface cable  670  has its wire elements respectively connected to the connector terminals  662  of the connector  654 . The interface cable  670  runs along the rear surface of the rear surface element  604 , and into the inner surface hole of sliding connector  680 . 
       FIGS. 7 and 8  show two fail-safe holes  700  and  702  provided in left and right pieces  600  and  602  respectively. A sturdy safety cable can be threaded through fail-safe holes  700  and  702  and around the cylindrical support  402  (or through some fixture attached to the lamp pole), to secure the hook clamp  400  to the cylindrical support  402 , even if its tongue  420  is not yet secured against support  402 . This allows a technician installing the lamp to secure the hook clamp and lamp assembly to the pole with a safety cable through at least one of the holes and around the supporting pole  402 . The cable can remain securing the lamp and hook clamp, even in the event of any failure of the hook clamp mechanism. 
     A particularly preferred and alternative embodiment of the invention enables an alternative mounting mechanism for the hook clamp. The left and right pieces of the hook clamp  602  are formed with special mounting flanges shown as  702 ,  704 . The otherwise planar end pieces  602 ,  604 , have mounting flanges, which extend in a perpendicular direction to the plane formed by the left and right pieces. Those mounted flanges can be used for an alternative mounting system which is shown in  FIGS. 9A ,  9 B and  10 . The hook clamp is shown in  FIG. 9A , mounted in an upside down position as compared with the position of pole mounting. In this position, the flange surfaces  704 ,  706  hold the hook clamp in place, as compared with the normal position in which the inside surfaces  404 , etc. hold the hook clamp in place. The flange  704 ,  706  have respective outer surfaces  708  which are held by a clamping mechanism  900 . The clamping mechanism  900  includes clamping surfaces  901  which respectively clamp against the clamped surfaces  706  of the hook clamp. 
     Clamping plate  902  includes a plurality of tightenable bolts  904 , and a plurality of fixed bolts  906 . When bolts  904  are loosened, the clamp  904  pivots relative to the fixed bolts  906 . The clamping surface of clamp  900  at end  910  can be lifted up slightly from the underlying support  912 . The end  910  preferably includes an upwardly extending flange, which slips over the clamping surfaces  708 . This facilitates locating the surfaces  708  into their proper location. The entire clamping surface  901  of the clamp can be lifted slightly from the underlying surface  912 . Once the clamping surfaces  708  are located into their proper position, the tightenable bolts  904  are tightened to thereby tightly press the tightening surfaces  901  against the corresponding tightening surfaces  708 . The clamp in place is shown in  FIG. 10 . Note that the clamp surfaces hold the supporting pole in the same way as in the other manner of tightening. Moreover, the tongue portions are omitted from the  FIGS. 9A ,  9 B and  10  figures, however, it should be understood that these tongue portions would preferably hold the lamp into place. 
     An important feature of this alternative embodiment is its ability to allow the lamp to be mounted into two different mounting locations using the same mounting structure. 
     A dual hook clamp embodiment is shown in  FIG. 11 . This embodiment shows a dual hook clamp assembly  1100 , with a special carrying handle  1105 . The clamp assembly can also be rotated in special ways. 
       FIG. 11  shows an electrical connection. Cables  1110  and  1115  are the main cables in the lamp which receive power, data, and diagnostics, and are routed through the hook clamp assembly  1100 , through central aperture  1130 , and down into the main lamp assembly. The rear housing part  1120  has connector mounting apertures for mounting connectors which are permanently attached to cables  1110  and  1115 . External cables with appropriate mating connectors can the be plugged into the permanently mounted connectors in the hook clamp, thereby providing easily removable power, data and diagnostics connections to the lamp. 
     The clamp assembly includes two hook clamps  1140  and  1150 , each of which has the configuration described above. Specifically, each has inner surfaces defining a cylinder, and a tightenable tongue. 
       FIG. 12  shows an arrangement of the hook clamp and shows how the device is rotatable. A rotation plate  1200 , shown in more detail in  FIG. 13 , allows setting initial orientation relative to other lamps and thereafter controlling all lamps in a group as though they were the same. 
     Lamps may be oriented in different directions when set up. For example,  FIG. 14  shows a truss  1400  that has a number of different parts with different orientations relative to one another. Section  1402  makes a  450  angle with section  1404 . Hence, the lamp  1403  is set at a different angle than the lamp  1405 . Similarly, truss sections  1406  and  1408  hold lamps  1407  and  1409  that have different angles of orientation relative to one another. However, in this embodiment, they may all need to be pointed in the same, or a similar direction to one another when in their “zero” (reset) positions. This orientation allows all the lamps to have the same range of controlled movement relative to the stage/studio area during operation. 
     An initial orientation of the lamp can be set using the rotation plate  1200 . Support bracket  1210  provides structural support for the lamp. Bearings contained within the support bracket  1210  allow the bracket to rotate freely relative to the hook clamp assembly  1100 , thereby allowing free rotation of the lamp. However, mechanical end stops e.g.  1201 ,  1202  contained within the whole assembly restrict the rotation of the support bracket relative to the hook clamp assembly within a specified range. This is because cables pass through the center axis of the assembly and these cables have a limited range of “twist”, so the range of rotation needs to be mechanically restricted. 
     In this particular embodiment, the “zero” position of the lamp is determined as the midway position between the two end stops, i.e. half way through the range of rotation, although it could equally be set at one or other end of the rotation range, or any position within the range. Essentially, the “zero” position is a position known to the drive electronics relative to the mechanical limit of rotation. 
       FIG. 12  shows a hook clamp assembly  1100  and a support bracket  1210 . As previously described, the support bracket  1210 , which holds the lamp, is freely rotatable relative to the hook clamp  1100  within the limits of the end stops contained within the assembly. Rotation plate  1200  is held captive within the hook clamp assembly but is able to rotate if nut  1220  is loosened. Nut  1220  is threaded onto a bolt which is fixed into the hook clamp and passes through a radial slot  1230  in the Rotation Plate  1200 . The nut has a bottom surface that, when the nut is tightened, presses against the plate surface  1315  and locks the rotation plate in position. The rotation plate  1200  is directly attached to the mechanical end stops within the assembly via a central shaft, and the rotational relationship between the rotation plate and the end stops is permanently fixed. The slot  1230  allows the rotation plate  1200  to be rotated relative to the hook clamp  1100  whenever the nut  1220  is loosened. Because the rotation plate is directly and permanently attached to the end stops, rotating the rotation plate alters the position of the end sops relative to the hook clamp  1100  and thereby adjusts the “zero” position of the lamp relative to the hook clamp. In this way, the lamp can be adjusted into any rotational orientation relative to the other lamps on the truss irrespective of the orientation of the hook clamp. 
     When the nut is loose, lamp holding part can rotate relative to clamp body  1100 . This rotation changes the orientation of the lamp relative to the body. The rotation is shown in  FIG. 13B , which shows how the pan shaft can rotate relative to the body. 
     In operation, all lamps in a group, i.e., those that need to be controlled together, are oriented so that their base position, their “zero” position, is the same. Using the FIG.  14  example, lamp  1405  is mounted with the plate set at −45 degrees,  1403  at zero degrees,  1407  at +45 degrees, and  1409  at 90 degrees. When the plates are mounted in this way, each of the lamps has a reset position, which is in the same direction. Therefore, they can be controlled as though they were all mounted, oriented, and facing in the same direction. 
     The carrying handle  1105  is installed between the two hooks  1140  and  1150 , mounted into corresponding holes  1142 ,  1152  in each one. The handle is mounted at a specified location, below and behind any location that might cause it to clash with the structure of the truss, either during hanging, or when hung, and thereby not reducing the number of installation possibilities, or restricting the operation of installing the lamp, compared to if there were no handle present. 
     Once the lamp is hung and secured, it can be rotated to a desired orientation using the rotation plate  1200  and the nut  1200  tightened to secure the plate and thereby set the “zero” position of the lamp. 
     This can facilitate installation, since the same lighting effect can be obtained by installing on any truss facing in any desired direction. 
     Although only a few embodiments have been described in detail above, those having ordinary skill in the art will certainly understand that many modifications are possible in the preferred embodiment without departing from the teachings thereof. 
     All such modifications are intended to be encompassed within the following claims.