Abstract:
A highly-compactable camera crane enables a load platform to be kept level as the boom is raised and lowered. A main boom is comprised of a number of crossed links which pivot at their crossings to allow extension and retraction of the boom and an auxiliary boom of similar crossed link construction couples the load platform to a reference pivot point of the main boom, enabling the load platform to be kept level as the booms are moved up and down relative to the pivot point.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 62/231,086, filed Jun. 25, 2015, which is incorporated herein by reference. 
    
    
     BACKGROUND 
     Many lifting and positioning devices use a boom structure to lift and position a load. In some applications, the load platform needs to be kept level as the boom is raised and lowered. Some examples are a boom where the load is a person, or booms used to smoothly move and position an operating motion picture camera. 
     With a boom of fixed length, a common technique of maintaining a level load platform is through the use of an auxiliary fixed-length boom or arm, above or below the load-carrying boom, and parallel to the boom. This arrangement forms a parallelogram. If the attachment points for the boom and the second arm are collinear and perpendicular to the ground, and the boom and arm are equal lengths, then the attachment points at the other ends of the boom and arm will also remain collinear and perpendicular to the ground as the boom is raised and lowered. Any platform then attached at the end of the boom, perpendicular to the line formed by the attachment points of the boom and the arm, will thus be parallel to, and therefore level with, the ground at any height of the boom. 
     A shortcoming of these devices in the current art is their mechanical complexity, requiring time-consuming assembly and disassembly each time they are used. Another shortcoming is that, due to the nature of the boom designs in the current art, they often have a relatively long minimum fixed length dimension even when disassembled, making them difficult to transport. Still another shortcoming is that most if not all assembly methods entail the use of peripheral fasteners, clips, pins and other hardware that are easily lost over the courses of assembly, disassembly and transit. 
     In view of this, it would be desirable to develop a method or methods of constructing or fabricating a highly compactable camera crane. 
     SUMMARY 
     The present invention is a unique and innovative solution to the limitations and shortcomings of the devices in the current art. 
     In one aspect, the invention is a highly compactable camera crane comprising two components: a fulcrum supporting a first boom constructed of a series of crossed links to enable simple and rapid extension for use and retraction for transport, and a similarly constructed second boom, pivotably connected to a load platform. The first boom may be pivotably connected near the center of its length to the fulcrum and at its distal end to the load platform. The second boom may be pivotably and removably connected between the fulcrum and the load platform such that the orientation of the load platform is maintained as the first and second booms are pivoted up and down about the fulcrum. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a highly compactable camera crane shown in an extended configuration; 
         FIG. 2  is a left side elevational view of the highly compactable camera crane with the boom level; 
         FIG. 3  is a left side elevational view of the highly compactable camera crane with the boom raised; 
         FIG. 4  is a left side elevational view of the highly compactable camera crane with the boom lowered; 
         FIG. 5  is a left side elevational view of the highly compactable camera crane in a partially retracted configuration; 
         FIG. 6  is a left side elevational view of the highly compactable camera crane in a fully retracted configuration; 
         FIG. 7  is a top plan view of the highly compactable camera crane shown in an extended configuration; 
         FIG. 8  is a front elevational view of the highly compactable camera crane shown in an extended configuration; 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the invention will now be described with reference to the figures, wherein like numerals reflect like elements throughout. The terminology used in the description presented herein is not intended to be interpreted in any limited or restrictive way, simply because it is being utilized in conjunction with detailed descriptions of certain specific embodiments of the invention. Furthermore, embodiments of the invention may include several novel features, no single one of which is solely responsible for its desirable attributes or which is essential to practicing the invention described herein. 
       FIGS. 1 through 8  show one embodiment of a highly compactable camera crane. 
       FIG. 1  is a perspective view of a highly compactable camera crane shown in an extended configuration. A main boom  110  may be comprised of a number of connected crossed links  120  in a scissor like configuration which pivot at their central  130  and distal  140  connections to allow extension and retraction of the boom. The main boom may be reversibly locked into an extended configuration by a locking arm  150  which may pivot about a distal axle  160  of a link  120  and removably capture the vertically adjacent distal axle  170 . The main boom may be pivotably connected to an axle  175  of a fulcrum structure  180 . In some embodiments, one end of the main boom  110  may be hingedly and removably connected to an axle  185  of the load platform  190 . In other embodiments, one end of the main boom  110  may be hingedly and removably connected the load platform  190  using a pull pin  185  secured to the main boom by means of a lanyard. The other end of the main boom may have a feature  195  allowing removable attachment of supports  196  that accommodate counterweighting disks  197 . 
     An auxiliary boom  200 , constructed of crossed pivoting links similar to the main boom thus allowing similar extension and retraction. In some embodiments, the auxiliary boom  200  is hingedly and removably attach to an axle  210  on the fulcrum structure vertically offset from the main boom axle  175  of the fulcrum structure. In other embodiments, the auxiliary boom  200  is hingedly and removably attach to the fulcrum structure using a pull pin  210  secured to the auxiliary boom by means of a lanyard. The other end of the auxiliary boom may hingedly and removably attach to an axle  215  of the load platform  190 . 
     The fulcrum structure may include a base  220  allowing rotation of the entire crane assembly about the vertical axis of the fulcrum structure. The fulcrum structure may further include lifting handle disposed at the upper end of the fulcrum structure. 
       FIG. 2  shows a left-side elevational view of the highly compactable camera crane of  FIG. 1  with the main and auxiliary booms parallel to the ground and with the top surface of the load platform  190  kept parallel to the ground by the parallelogram configuration  225  created by the main boom and its attachment at the lower fulcrum axle  175  and the lower load platform axle  185 , and the auxiliary boom and its attachment at the upper fulcrum axle  210  and the upper load platform axle  215 . 
       FIG. 3  shows the camera crane of  FIG. 1  with the load platform  190  raised and with the top surface of the load platform kept parallel to the ground by the parallelogram configuration  225  created by the attachment points to the fulcrum and the load platform. 
       FIG. 4  shows the camera crane of  FIG. 1  with the load platform  190  lowered and with the top surface of the load platform kept parallel to the ground by the parallelogram configuration  225  created by the attachment points to the fulcrum and the load platform. 
       FIG. 5  shows a left elevational view of the auxiliary boom  200  and load platform  190  assembly with the auxiliary boom in an extended configuration. The load platform is pivotably connected to a distal end of the auxiliary boom. 
       FIG. 6  shows the auxiliary boom  200  and load platform  190  of  FIG. 5  with the auxiliary boom in a compacted configuration and the load platform rotated to a maximally compacted position. 
       FIG. 7  shows a left elevational view of the main boom  110  and fulcrum structure  180  assembly with the main boom in an extended configuration. The fulcrum is pivotably connected to the main boom at an intermediate position. 
       FIG. 8  shows the main boom  110  and fulcrum structure  180  of  FIG. 6  with the main boom in a compacted configuration. 
     Thus for transport the main boom and fulcrum assembly and the auxiliary boom and load platform assembly may be retracted to a fraction of their extended lengths, as shown in  FIG. 6  and  FIG. 8 . 
     In one embodiment, the load platform may be pivotable for transport, with the pivotability feature being achieved without the need for any unconstrained hardware or tools. 
     In one embodiment, counterweight disk support members may removably attach to the distal end of the main boom without the need for any unconstrained hardware or tools. 
     In one embodiment, counterweight disk support members may removably attach to features at the distal end of the main boom for transport, such that the support members are oriented parallel and coaxial with the distal links when the boom is in a compacted configuration without the need for any unconstrained hardware or tools. 
     In one embodiment, attachment of the load platform to the main boom may be facilitated by a pull pin secured to the main boom by means of a lanyard. 
     Thus the aforementioned shortcomings of devices in the current art are overcome in the current invention, which provides significant novel improvements in design, versatility, transportability, ease of assembly and disassembly, and usability. 
     It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims. In addition, where this application has listed the steps of a method or procedure in a specific order, it may be possible, or even expedient in certain circumstances, to change the order in which some steps are performed, and it is intended that the particular steps of the method or procedure claims set forth here below not be construed as being order-specific unless such order specificity is expressly stated in the claim.