Patent Publication Number: US-6666570-B2

Title: Adjustable mounting system for a directional light

Description:
FIELD OF THE INVENTION 
     This invention relates generally to mounting systems for light fixtures, and particularly to mounting systems for directional lights. 
     BACKGROUND OF THE INVENTION 
     Concerts, shows, and other events make extensive use of spotlights and other directional lights to illuminate the stage, sets, and participants. In order to meet the lighting requirements of such events, these lights must be capable of being directed in various directions. They must also be stably mounted and are preferably easily portable. However, these functions have previously been mutually exclusive. 
     It is known, for example, to fix lights to yokes which in turn are suspended from crossbars suspended horizontally by means of clamps; however, these lights, while they are somewhat adjustable, are not easily portable since the crossbars and the mounting means for the crossbars are relatively large compared to the size of the light. 
     Furthermore, this type of mounting system only provides one means for adjusting the orientation of the light, via the clamp on the crossbar. When additional accessories are added to the lights, such as colour changers, lenses, or filters, the extra weight of these accessories causes the centre of gravity of the light to shift. Furthermore, adjustments to the focal length of a lens accessory, which can result in an extension or retraction of the accessory of several centimeters, also changes the centre of gravity of the light. A change in the centre of gravity of the light places additional stress on the clamp holding the light in the desired place, which can cause shifting of the light during use and unnecessary wear on the clamp and crossbar. 
     There is therefore a need for a mounting system which provides for adjustments to compensate for changes in weight and shifting of the centre of gravity of a light and/or accessories, which provides sufficient stability to resist shifting of the light during use while being easily portable, and which does not restrict the ability to adjust the direction of the light. 
     SUMMARY OF THE INVENTION 
     The invention overcomes these disadvantages by providing an adjustable mounting system for a directional light which is portable and stable, but does not restrict the ability to direct the light at a desired target. 
     Accordingly, the invention accomplishes this by providing a mounting base for an adjustable mounting system to which the light is articulated by a yoke having pivot points about both the base and the light. In the preferred embodiment the base comprises first and second pedestals, and a cylindrical crosspiece extending between the first and second pedestals. The invention accordingly provides an adjustable mounting system for directional lights which allows easy adjustment of the light to accommodate changes in the location of the center of gravity caused by adding or making adjustments to accessories, while keeping the orientation of the light on target. 
     In the preferred embodiment the light mounting system comprises the aforesaid mounting base, a yoke pivotably engaged to the light and having a releasable clamp which is pivotably engageable to the crosspiece of the mounting base. The mounting system thus has two pivotable engagement points, each of which may be adjusted independently in mounting a light to the base. Adjustments at these pivotable engagement points thus provide for the alignment of the centre of gravity of the light, including any accessories attached to the light, generally above the mounting base, thus increasing the stability of the system without having to remove the light from the mounting system without impeding the adjustability of the direction of the light. 
     In the preferred embodiment flanges are provided at the bottom of at least one of the pedestals, the flanges being provided with bore holes, for use in fastening the mounting base to a fixed support, such as a truss or a platform. Also, in a preferred embodiment, the mounting base is configured such that the crosspiece is fixed between two inside faces of the pedestals. 
     The present invention thus provides an adjustable mounting system for a directional light, comprising a yoke having a first end for pivotably engaging the light at a first adjustable pivot, and a second end providing a releasable clamp, a base comprising a support supporting a crosspiece for fastening the clamp to the base at a second adjustable pivot, a first fixing element for fixing the first adjustable pivot, and a second fixing element for fixing the second adjustable pivot, wherein the first and second adjustable pivots are independently adjustable to adjust a direction of the light and a position of the light relative to the base. 
     The present invention further provides a base for mounting a directional light pivotably engaged to a yoke at a first adjustable pivot, the yoke being provided with a releasable clamp, the base comprising a support supporting a crosspiece for fastening the clamp to the base at an adjustable pivot. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In drawings which illustrate by way of example only a preferred embodiment of the invention, 
     FIG. 1 is a perspective view of a preferred embodiment of the mounting base of the present invention; 
     FIG. 2 is a side elevation of a preferred embodiment of the mounting system of the present invention showing an accessory mounted on a light; and 
     FIG. 3 is a side elevation of the mounting system of FIG. 2 showing the light repositioned to accommodate a change in the center of gravity arising from removal of the accessory. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     Referring to FIG. 1, an embodiment of the mounting base  10  of the present invention is shown. The mounting base  10  provides supports, in the preferred embodiment comprising pedestals  12 ,  16  having substantially flat lower surfaces  14 ,  18  for resting on a level floor or platform. A cylindrical crosspiece  20  is fixed to the pedestals  12 ,  16  such that the crosspiece  20  is substantially parallel to the lower surfaces  14 ,  18 , i.e. generally horizontal when in use. 
     In the embodiment shown in FIG. 1, the pedestals  12 ,  16  have a generally triangular shape with the crosspiece  20  fixed to the interior sides of the pedestals  12 ,  16  at the apex of the triangle. Preferably, pedestals  12 ,  16  are provided with flanges  13 ,  17  respectively which are provided with bore holes  19  for optionally fastening the mounting base  10  to a platform or truss (not shown). The mounting base  10  may be assembled from individual pieces or provided as an integral piece of cast metal, moulded plastic or any other suitable material. 
     An embodiment of the mounting system  100  is shown in FIG. 2. A light  50  is pivotably mounted on a yoke  40  in a configuration which is known in the relevant art. In the drawings, the cross-section of the light  50  is shown as substantially circular and having an axis l through its centre; where the light  50  has another cross-sectional configuration, the axis l is a longitudinal axis through the body of the light  50 . The orientation of the light  50  with respect to the yoke  40 , as indicated by the angle θ between the plane of the yoke  40  indicated as y in FIG.  2  and the longitudinal axis l, is adjustable by means of the pivot provided by the yoke  40 , and may be releasably secured by means of a fixing element, such as a nut  42  engaged to bolts projecting from the housing of the light  50 , at any desired angle of the light  50  to prevent further rotation at the pivot point. 
     The yoke  40  is further provided with a releasable clamp  30 , such as a C-clamp having a clamp arm  32  and fixing element, for example a bolt  34 , threadedly engaged through the clamp arm  32 . 
     The light  50  may be provided with additional, optional accessories  60 , such as a filter or colour changer, which are typically mounted on the front of the light  50  and may be exchanged for other accessories, adjusted, or removed as necessary. Any accessory  60  adds weight to the front of the light  50 . 
     Mounting of the light  50  onto the mounting base  10  is easily accomplished by applying the clamp  30  provided on the yoke  40  to the crosspiece  20  of the base  10 , and adjusting the fixing element  34  to bear against the crosspiece  20  and lock the yoke  40  in position on the base  10 . The plane y of the yoke  40  forms a mounting angle φ from the horizontal, as shown in FIG.  2 . 
     Once the light  50  with optional accessories  60  is mounted on the base  10 , the angles θ and φ can be adjusted so that light from the light  50  is directed at the intended target, while the center of gravity of the assembled light  50  and accessory  60  is positioned substantially over the crosspiece  20 , so that the mounting system  100  as a whole is stabilized. The angle θ is adjusted by releasing the screw nut  42  fixing the angle θ between the yoke  40  and the light  50 , if necessary, pivoting the light  50 , and tightening the screw nut  42 . The angle φ is adjusted by loosening the clamp  30 , pivoting the clamp  30  around the cylindrical crosspiece  20 , and fastening the clamp  30  in the desired position. 
     The direction of the light beam from the light  50  may be adjusted by altering the orientation of the light  50  with respect to the yoke  40  (angle θ) as well as by altering the mounting angle φ. These two angles preferably should also be adjusted as necessary to ensure that the centre of gravity of the light  50  (and any optional accessories  60 ) is located above the crosspiece  20  in order to maximize the stability of the mounted light assembly. By altering the angles θ and φ, it is possible to direct the light from the light  50  easily over a range of about 150° while maintaining the mounted light assembly in a stable orientation. 
     Optionally the mounting base  10  may be fixed to a support such as a floor, platform or truss by means of bolts fastened to the support through the bore holes  19 , in which case the location of the centre of gravity of the assembled light  50  and the accessory  60  directly above the base  10  may be less important. By providing the bore holes in the flanges, the mounting base  10  thus acts as an adaptor plate for use on a truss for mounting the light  50 . 
     The addition of a fixture  60  to the light  50  adds weight to the front of the light  50  such that the centre of gravity of the light/fixture assembly is shifted towards the front end of the light  50 . If an accessory  60  is removed from the light, the centre of gravity of the light  50  will be shifted towards the back of the light  50 . The light  50  is articulated to the base  10  by yoke  40 , so that if an accessory  60  is removed from or added to the light  50  while it is mounted to the mounting system  100 , the angles θ and φ may be adjusted as necessary to realign the centre of gravity of the light  50  above the base  10 , as can be seen in FIG. 3 in phantom lines in which the accessory  60  shown in FIG. 2 has been removed from light  50 ′. Similarly, the mounting system  100  may be adjusted to accommodate changes to an accessory  60  mounted on the light  50 . For example, adjustment to the focus of a telephoto lens may result in the extension or retraction of the lens over 25 centimeters or more, which could result in a significant change in the centre of gravity of the system. Again, angles θ and φ may be adjusted as necessary to realign the centre of gravity of the light  50  above the base  10 . 
     Thus, in FIG. 3 the phantom angle θ′ between the yoke  40 ′ and the light  50 ′ is smaller than the angle θ between the yoke  40  and the light  50 . The angle φ has also been altered, with the effect that the centre of gravity of the light  50 ′ is still disposed above the base  10  while the direction of the light  50 ′ remains unchanged. 
     Various embodiments of the present invention having been thus described in detail by way of example, it will be apparent to those skilled in the art that variations and modifications may be made without departing from the invention. The invention includes all such variations and modifications as fall within the scope of the appended claims.