Abstract:
The invention relates to a monopod device for use with a camera, which uses one or more constant force helical springs to counterbalance the weight of a camera and lens, as well as a camera tilt mechanism, the combination of which effectively provides weight compensation that significantly reduces the lifting force required by a user to move the camera and provides stable image capture, camera control, and a reduced footprint when compared to existing tripods.

Description:
FIELD OF THE INVENTION 
     This invention relates to an improved monopod mounting device especially useful for still or video camera and lens combinations but is also useful for firearms, spotting scopes and the like. 
     BACKGROUND OF THE INVENTION 
     Users of optical devices, such as cameras, spotting scopes, or high power binoculars have difficulty in holding their handheld steady enough from the offhand position to ensure adequate accuracy for long-range shots. Furthermore, it is often difficult to target and remain affixed steadily on an object even at short range for extended periods. After a few seconds of hold, the user&#39;s stability generally decreases to the point where adequate definition of the object being studied is lost. An attachment or stand to assist the users of these devices in achieving adequate steadiness would be very desirable. 
     Solutions that have been devised include harnesses and shoulder support systems to accommodate and compensate for user movement. These systems, though effective, are expensive, cumbersome, often require training and experience to operate effectively and are usually limited to use by professional cameramen. The most reasonable alternative are stands and these comprise tripods and monopods with each having their own intrinsic advantageous and limitations. Most monopods and tripods are made up of a plurality of elongated sections arranged in a telescopic manner to extend the length of the pod. 
     Tripods are advantageous from the stability point of view, but the need to adjust each leg of the tripod to ensure correct vertical height adjustment requires both physical exertion and focused attention. The effort and time needed to deploy the tripod can be better dedicated to the task of image composition and acquisition. Since increased stability requires a larger tripod footprint on which the legs can be spread out, it is not uncommon for its users to trip over or have camera accessories such as cables and cords get entangled with the extended legs of the tripod. Furthermore, they are generally relatively bulky and heavy to move/transport, as well as being complicated to set up, particularly on uneven surfaces or surfaces which are not horizontal. Monopods, on the other hand, weigh little and take up little space during transportation, they are quick to set up, easy to move with a camera attached while work is in progress, can be placed on substantially any surface and only require a small area. 
     However, these traditional tripods and monopods that are currently available in the market are of the telescoping leg kind comprising two or more hollow shafts that are slideably connected to each other and engaged by means of an interference fit or clamps which retain them together at the desired position of retraction or extension. Such telescoping means are commonplace and generally utilize an interference fit in order to achieve engagement. U.S. Pat. No. 7,222,827, entitled “Telescoping Leg Lock With Thumb Actuator” to Crain et al. describes one such clamping method, and U.S. Pat. No. 5,903,995 entitled “Monopod” to Brubach describes another clamping method for telescoping legs. In particular, the Brubach patent exhibits a monopod that can be raised or lowered to virtually any position in the vertical plane while still maintaining level sight alignment. This is accomplished by means of choke collars that are known in the art. However, the Brubach patent does not provide for a counter balancing system to permit a smooth, controlled raising and lowering of the camera and requires the need to release and relock extensible rods. 
     U.S. Patent Application No. 200201797895 entitled “Monopod Camera Stand” to Boyd et al. shows a series of rod connectors that limit the position of the camera to distinct fixed positions relative to the ground. 
     A further limitation associated with the effective use of traditional tripods and monopods utilizing hollow telescoping legs for still or video camera image capture are in situations and events where high mobility is required such as photojournalism, sporting events, concerts, ceremonies, where the need to extend/retract and further to continually de-clamp/re-clamp the hollow telescoping legs is limiting. This limitation therefore impedes the use of these traditional tripods and monopods in situations where rapid response is crucial to visually record an impromptu or short-lived event. 
     There is therefore a need in the marketplace for a robust, simple-to-use monopod support and stabilization system that offers controlled but rapid repeatable stability in a variety of environments, and which is affordable by the larger general consumer camera enthusiast, as well as the professional photographer, and which avoids or overcomes the limitations to the systems described above. 
     SUMMARY OF THE INVENTION 
     The present invention substantially departs from the prior art concepts and designs of known monopods. No existing monopod provides the benefits attributable to the present invention. Additionally, the prior art cited neither suggest nor teach the present inventive combination of component elements arranged and configured as disclosed and claimed herein. 
     As recited earlier, the present invention is useful for any handheld apparatus such as a still or video camera and lens combination, as well as for firearms, spotting scopes and other handheld equipment. For the sake of simplicity, this specification will refer to any such apparatus as a camera. In a preferred embodiment of the present invention, provided is an apparatus that is a monopod, which is a hollow shaft, within which a constant force helical spring counterbalance mechanism is contained and is the means by which camera weight compensation is achieved without complex adjustment, engagement or control means. 
     According to this embodiment of the present invention, vertical adjustment of the camera is achieved by integrating into the monopod a constant force helical spring, one end of which is connected to a stationary component affixed to the top of the monopod and the other end of said helical spring being attached to a movable plug that is movable within the hollowed portion of said monopod. In accordance with one embodiment of the invention, there is provided a camera mount bracket to connect it to the monopod to steady the camera. 
     Said movable plug is either formed as an integrated element with or may be mechanically or electromechanically attached to the camera mount bracket that is external to the monopod via one or more slots that is formed parallel to the longitudinal axis of the monopod shaft. Said camera mount bracket is designed to interface with, engage and retain a camera. Further, the constant force helical spring is selected to generate a counter-force to help counteract the combined weight of the movable plug, the external camera mount bracket, and the camera and lens. 
     With the apparatus according to the present invention, the weight of the movable camera may be exactly or partially counterbalanced so that the force that the photographer needs to exert to raise the camera is reduced. In some situations, a photographer may need to use large lenses that may be sometimes much heavier than even the camera it is connected to. In this event, by appropriate selection of constant force helical spring, even large, cumbersome camera-lens combinations may be lifted. This reduces manual exertion and allows greater mobility and control of the camera. 
     In another embodiment of the present invention, the apparatus or monopod may comprise a plurality of constant force helical springs optimized to accommodate for a large range of camera and lens weights, said constant force helical springs being connected to and disposed between the moveable plug and a stationary component as previously described. 
     Additionally, the monopod of the present invention may either be designed so that its bottom end is releasably attached to a traditional tripod described earlier where conditions permit, or may be a stand-alone apparatus when conditions for traditional tripods become unfriendly. Alternatively, the monopod bottom end can be designed so that it may be accessorized with any selection of low profile studio and outdoor bases currently available via a variety of snap-on specialty mounts. The entire system can be converted into a portable camera and lighting package to establish a controlled photographic stage for repetitive documentation purposes. 
     A key feature of the present invention is the use of constant force helical springs as the counter balance force and means for stable control of the height of the camera mounted on the camera mount bracket. Constant force springs are a type of extension spring that generally consists of a spiral material with built-in curvature so that each turn of the strip wraps tightly on its inner neighbor. However, unlike standard compression springs, when the strip of the constant force spring is extended, the inherent stress resists the loading force just as in a common extension spring but at a nearly constant zero rate. 
     In the present invention, since the relationship between input deflection and the output force is fixed for constant force springs, the user has the advantage that the control effort to raise or lower the camera is minimized. 
     Springs and other elastic materials generally follow the approximation described by Hooke&#39;s law of elasticity, wherein the extension of a spring is in direct proportion with the load added to it as long as this load does not exceed the elastic limit. Materials for which Hooke&#39;s law is a useful approximation are known as linear-elastic or “Hookean” materials. However, constant force springs deviate from Hooke&#39;s law and the force it exerts over its range of motion is a constant. 
     A primary objective of the present invention is to provide for a monopod apparatus with advantages that are not provided or taught by prior art. 
     Another objective of the present invention is to provide for a non-pneumatic support apparatus capable of supporting a camera over a useful, flexible range of heights without the use mechanical clamps or chokes to retain the camera in place. 
     Another objective of the present invention is to provide for a camera support apparatus that is versatile and responsive to the needs of users to enable them to capture rapidly changing events. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a rear elevational view of the present invention with a camera shown in operative position ready to take a picture; 
         FIG. 2  is an enlarged, cross-sectional, elevational view of a portion of the hollow shaft of  FIG. 1 ; 
         FIG. 3  is an exploded, side elevational view of the helical spring and movable plug assembly of the present invention in  FIG. 1 . 
         FIG. 4  is an enlarged, cross-sectional, elevational view of the camera mount and tilt mechanism of the present invention in  FIG. 1 . 
         FIG. 5  is a top view of the present invention in  FIG. 4  taken along the line X-X. 
         FIG. 6  is a rear perspective view of the camera mount bracket. 
         FIG. 7  is a cross-sectional, elevational view of the camera mount bracket of the present invention taken along the line Z-Z. 
         FIG. 8  is an end view of the camera mount bracket only in  FIG. 6  taken along the line Y-Y. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which a preferred embodiment of the invention is shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, this embodiment is provided so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those skilled in the art. 
     Referring now to the drawings, there is shown in  FIGS. 1 and 2 , an embodiment of the present invention, which is a monopod, generally designated  10  that is lightweight and portable. It provides support to the camera  11  and enhances user control throughout the slotted length of its permitted travel along the hollow shaft  12 , and the up and down tilting of the camera. The slotted length is defined by a hollow shaft slot  13  that runs along a part of the length of the hollow shaft  12 . The hollow shaft  12  has an upper end  7  and lower end  9 , and comprises the primary mechanism of the embodiment of the present invention and is able to stand alone or on an assortment of bases such as a foot plug  14 . Also shown is a support leg  16  that is joined to the hollow shaft  12  in order to extend the gross working vertical length of the monopod  10 , as well as a camera mount and tilt mechanism  79 , which facilitates the retention and control of a camera. 
     The hollow shaft  12  incorporates the primary mechanism of the monopod  10 , and has a hollow shaft head  19  to which capsules  30 ,  30 ′ are attached and a hollow shaft foot  18  that enables the monopod to either stand alone or on an assortment of bases. The hollow shaft  12  is connected at its hollow shaft foot  18  to a support leg  16  by means of a connector plug  14  to thereby extend the gross working vertical height of the monopod  10 . The connector plug  14  is generally cylindrical and formed so that its end forms an interference fit with the internal surface of the hollow shaft  12  and support leg  16 , and is over sized in the middle to form a connector plug spacer  15  to prevent damage to the hollow shaft and support leg. The support leg  16  may be any one of a variety of tubes, stands, and tripods; alternatively, if an extension is desired, the foot plug  17  at the base of the support leg  16  can be replaced by a variety of tubes, stands, and tripods to broaden the versatility of the present invention across an increased range of photographic opportunities and environments. Alternatively, the foot plug can also be supplied with a spiked end to enable placement of the monopod on the ground. 
     Referring also now to  FIG. 3 , shown is an enlarged view of the constant force spring mechanism which comprises constant force helical springs  20 ,  20 ′ that are connected to a movable plug  50  by pin  25  that fits into helical spring retaining hole  52 . More specifically, the constant force helical springs  20 ,  20 ′ sit at the top of the hollow shaft  12 . The movable plug  50  travels inside the cavity of the hollow shaft  12  as a result of its attachment to collar  60  which the user photographer causes to move. Movable plug  50  is attached to the collar  60  and collar sleeve  61  via collar pin  62 , which fits into plug retaining hole  53  through slot  13 . Since collar  60  travels along the outside of the hollow shaft  12  in tandem with the movable plug  50 , it therefore contributes to maintaining the mechanical integrity of the hollow shaft  12  by preventing its walls from buckling inward or outward. The collar  60  also supports a camera mount plate  80  upon which camera mount bracket  89  rests and provides for an up/down camera tilt feature. Collar sleeve  61  interfaces between the collar  60  and hollow shaft  12  and is selected from materials that ensure that it is slideably connected to the hollow shaft  12  and is intended to minimize friction as it slides along the length of the hollow shaft  12 . 
     Constant force helical springs  20 ,  20 ′ act as counterweight force means and are selected to counteract the loading force of the movable plug  50  and the other elements attached to the movable plug  50 , as well as in accordance with the specific desire of the photographer user. Constant force helical spring  20 ,  20 ′ are mounted with internal diameters tightly wrapped around drums  21 ,  21 ′ that ride on bearings  22 ,  22 ′ which are in turn held in place by axles  23 ,  23 ′ that are further retained by capsules  30 ,  30 ′. Constant force helical springs  20 ,  20 ′ will have the tendency to force the top of the capsules  30 ,  30 ′ away from each other. In order to hold capsules  30 ,  30 ′ in the positions shown in  FIG. 3 , container box  40  is used to counteract the forces. Those skilled in the art will realize that there are numerous means to hold or mechanically bond capsules  30 ,  30 ′ together. The free ends of the constant force springs attached to the loading force, which is the movable plug  50 , etc. The movable plug  50  also has a slot  51  to receive the constant force helical spring ends  24  and a hole  52  through which the spring ends  24  are secured by a pin  25 . In other embodiments, the load capacity can be increased by using a plurality of constant force springs mounted in tandem on top of each other. 
     Turning now to  FIGS. 4 and 5 , in addition to height adjustment, the present invention includes means to mount and control the camera&#39;s vertical attitude (up and down tilt) by a camera and tilt mechanism  79  that is mounted onto the collar  60 . Tapped holes in collar  60  receive coves  63 ,  63 ′ that convert one side of collar  60  into a flat plane. Spacer screws  64 ,  64 ′ retain coves  63 ,  63 ′ and the rear pressure plate  70  against the hollow shaft  12 . 
     The camera mount and tilt mechanism  79  includes a rear pressure plate  70  and front pressure plate  70 ′ and corresponding friction pads  81 ,  81 ′, which are used to sandwich a rotating camera mount plate  80 . A camera mount spindle  82  extends from the rotating mount plate  80  through to the front pressure plate  70 ′ and is mechanically attached to the camera mount tongue  83  using splines, screws, welding, chemical bonding or similar means. An element of the camera mount and tilt mechanism  79  is that the center of gravity of the camera is generally near the centerline of spindle  82 . Tightening pressure plate adjustment screw  72 ,  72 ′ forces friction pads  81 ,  81 ′ against rotating camera mount plate  80  thereby restricting its rotational movement. This permits the user to control the up and down tilt of the camera  11  from its free tilt position and further so that when the photographer is satisfied with the tilt angle and aim he can release the camera without changing the pre-adjusted camera tilt angle. The pressure can be adjusted according to the camera&#39;s size and weight. Furthermore, the moment produced by the weight of the camera  11  causes the collar  60  to tighten against the hollow shaft  12  and this enables both the collar  60  and the moveable plug  50  to which it is connected to hold fast against the monopod. 
     Turning now to  FIGS. 6 ,  7  and  8 , there is shown a camera mount bracket  89  and elements thereof. The camera mount bracket  89  comprises of a vertical mount bracket arm  90  and horizontal mount bracket arm  91  and are held together by bracket reinforcement screws  94 ,  94 ′ and is further configured to mate with and be attached to the base of the camera  11  by means of mounting bolt  95 , whose travel is limited to the length of the slot  93 , which is sized in order to adjust to a variety of cameras. In the usual upright, vertical position, the female dovetail groove  96  of the camera mount bracket  89  slides over the mating male dovetail camera mount tongue  83  of  FIG. 5 . For the horizontal position, longitudinally formed dovetail groove  92  is also formed to slide over mating male dovetail camera mount tongue  83  in a similar manner.