Photography – Camera support – Adjustable support
Reexamination Certificate
1999-07-14
2001-12-11
Gray, David M. (Department: 2851)
Photography
Camera support
Adjustable support
C248S123110, C248S372100
Reexamination Certificate
active
06328487
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a vertical plane counterbalancing structure, particularly for support heads for television or motion picture cameras.
As is well known, in fluid heads for camera supports, balancing the camera weight is necessary both on the horizontal plane and the vertical plane.
No difficulty exists in obtaining balance on the horizontal plane, since the weight of the camera is supported by a high efficiency system, generally comprised of a ball thrust bearing having a suitable diameter.
However, the problem relevant to balancing on the vertical plane is different, since the angular displacement of the camera causes a turning over moment, or an “acting agent”, which varies based on the angular displacement.
In order to obtain the same conditions as in the horizontal plane, the acting moment must be annulled by an opposite or “reagent” moment, having the same and opposite value all along the −90°/+90° motion arc.
In other words, the barycenter of the system (camera plus head) varies in any angular situation, so that it is practically impossible to obtain a perfect and constant balancing throughout the arc of motion.
The importance of an optimum balancing in any position along the 180° arc (−90°/+90°) is very high since it remarkably influences the quality of the film or video being shot.
At present, known counterbalance solutions do not provide a complete solution to the above problem along the whole arc of motion.
SUMMARY OF THE INVENTION
One objective of the present invention is to solve the above mentioned problems, providing a structure able to guarantee the balancing of the camera system (support head-camera) at any position along the use arc on the horizontal plane, as well as on the vertical plane.
These and other results are obtained according to the present invention by a counter-balancing technical solution that creates a reacting moment equal and opposite to the instantaneous acting moment, i.e., to the moment that must be considered as a variable, and at the same time allowing one to mount cameras having different weights. The system according to the present invention also is provided with adjustment means, allowing it to fit to different loads.
It is therefore a specific object of the present invention to provide a vertical plane counter-balancing structure, particularly for support heads for television or motion picture cameras, comprising means to fix the camera, a support for the fixing means, a first movable pulley system, the pulleys having offset and vertically movable rotation axes, an elastic means group, and at least two ropes or cables fixed, at one end, to the elastic means group, and at the other end to the support, the ropes or cables each passing on one of the pulleys of the first pulley system, the two ropes or cables alternatively acting by compressing the elastic means group, respectively when the load coupled with the fixing means is inclined with respect to the vertical at an angle between 0° and +90° and between 0° and −90°.
Preferably, according to the invention, a pair of fixed pulleys is provided, along the ropes, between the elastic means group and the first movable pulley system.
Still according to the invention, the elastic means group provides at least a spiral spring.
Preferably, two groups of spiral springs are provided, each one comprising at least a spiral spring, the relevant rope being coupled with the spring in such a way to stress the same under compression.
Furthermore, according to a preferred embodiment of the counter-balancing structure according to the invention, the elastic means group is provided vertically.
Still according to the invention, the movable pulleys have their axes offset a fixed value along the horizontal plane.
In an embodiment of the structure according to the invention, a single elastic means group is provided, the ropes or cables being both coupled on the same side of the elastic means group.
Preferably, the at least one elastic means group is removably housed within a housing element.
According to the invention, the ropes or cables are made of steel.
REFERENCES:
patent: 4208028 (1980-06-01), Brown et al.
patent: 5360196 (1994-11-01), DiGiulio et al.
Cartoni , S.p.A.
Gray David M.
Smith , Gambrell & Russell, LLP
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