Material or article handling – Horizontally swinging load support – Swinging about pivot
Patent
1995-06-01
1997-12-16
Merritt, Karen B.
Material or article handling
Horizontally swinging load support
Swinging about pivot
212197, 24828011, 901 48, B66C 2372
Patent
active
056977573
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to counter-balanced load carriers and is particularly, although not exclusively, applicable to load carriers for supporting television, video and cinematograph cameras.
Cameras for the above purposes are usually mounted on track or wheel mounted pedestals or on balanced arms. Pedestals are eminently suitable for use in open areas but are disadvantageous when the camera is required to move into a restricted space. Balanced arms such as the balanced arm described and illustrated in our U.K. Patent No. 2163720 enable a camera to be moved into a restricted space where a pedestal would not be able to move but involve a more cumbersome mechanism which is more difficult to transport and to store when not in use.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a counter-balanced load carrier which provides the enhanced access obtained with a balanced arm but which has a more compact form when not in use compared with that available hitherto.
This invention provides a counter-balanced load carrier comprising a multi-stage elongatable arm, a base on which the arm is mounted on one stage thereof for pivotal movement in a vertical plane about a horizontal axis, a support for a payload mounted on another stage of the arm and means to apply a counter-balancing load to the arm at a radius from said axis which varies automatically with extension and retraction of the arm in a fixed ratio with the radius of the payload support about said axis whereby the arm with a payload on the support is counter-balanced throughout its range of extension/contraction.
Preferably the arm is pivotally mounted on the base by a stage at or adjacent one end of the arm and the payload support is located at the other end of the arm.
It is further preferred that means are provided for controlling movement of the arm acting on a control point at a radius from said axis in a fixed ratio with the radius of the payload support whatever the extension/retraction of the arm whereby movements of the control point are reproduced by the payload in said fixed ratio.
More specifically the control means may include means to constrain the control point to move horizontally for horizontal movement of the payload support, to move vertically for vertical movement of the payload support or freely for any combination of horizontal/vertical movement.
In one particular arrangement according to the invention the control means may comprise a vertically extending guideway in which a guide located at said control point engages and a horizontally extending guideway which constrains movement of said guideway, means being provided for locking the guide at the control point in the vertical guideway and for locking the vertical guideway against movement along the horizontal guideway to control movement of the control point as required. In addition the vertically extending guideway may be supported on a carriage which is constrained to move along said horizontally extending guideway.
In a further arrangement according to the invention drive means may be provided for moving said control point horizontally, vertically or in any combination thereof.
By way of example the control point may be located on a stage of the arm adjacent to the stage on which the arm is mounted for rotation about said horizontal axis.
In any of the above arrangements the means to apply a counter-balancing load to the arm may comprise a weight and/or a force applying device acting vertically on the arm on the same or separate stages.
In one arrangement the arm may be pivotally mounted about said horizontal axis at a stage adjacent an end of the arm and a weight acts on the stage at said one end.
Further a force applying device may act on said end stage of the arm or on another stage of the arm on the other side of the horizontal axis.
Preferably the force applying device and/or weight are adjustable to cater to different payloads on the payload support.
In the case where the arm has a control point constrained to move in
REFERENCES:
patent: 3788585 (1974-01-01), Masseron
patent: 4907768 (1990-03-01), Masseron et al.
patent: 4943019 (1990-07-01), Mester
patent: 5186422 (1993-02-01), Nakamura
Merritt Karen B.
Morse Gregory A.
Vitec Group, plc.
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