Heavy-duty stabilized camera head with camera position sensing

A panhead (1) having a counterbalance action suitable for heavy cameras or equipment, and provides instantaneous electronic measurements of head settings and position. The improved counterbalance utilizes a dual-tower dual-axis non-linear mechanism as well as position encoders indexed to each axis (7-13) of head movement. Potentiometer setting detectors are also indexed to settable adjustments to read and relay such adjustments, and an electronic display (25) conveys information regarding the current positions and settings of the camera head (1). A novel mounting system situated at the top of the head provides for fast and simple mounting and unmounting of equipment or a dutch roll head. In particular, a novel dovetail (19, 21) engagement mechanism swings a dovetail side down during detachment. In an embodiment of the invention, the dutch roll head can be remotely proportionally actuated by a user via a switch mountable to a handle used for panning and tilting of the pan head.

TECHNICAL FIELD

This invention relates generally to equipment for supporting optical equipment and, more particularly, relates to a camera head for pivotally supporting a camera in a counterbalanced manner.

BACKGROUND OF THE INVENTION

Cameras have been and continue to be critical components in both motion picture and television feature production. An important criterion for the use of a camera in television or motion picture capture tasks is the ability to smoothly follow an action item, such as an athlete, with the camera. However, cameras usable in motion picture and television work are typically heavy and cumbersome to manipulate. For example, a standard television camera may weigh 100 pounds or more. Thus, in order for a camera to be manipulable so as to provide such smooth operation, it is desirable to balance the weight and inertia of the camera and to mitigate the effects of minor unintended forces on the camera by the operator.

In order to stabilize the motion of a camera on a camera head, it is typical to employ drag mechanisms. One such prior art drag mechanism is illustrated in U.S. Pat. No. 4,955,568 (“the '568 patent”) to O'Connor et al, entitled “Panhead For Camera,” which is assigned to the assignee of the present invention and is hereby incorporated by reference in its entirety for all that it teaches. In particular, the '568 patent illustrates an adjustable fluid drag mechanism. It is useful for camera operators to have ready access to data describing the various drag settings for the camera, so as to accurately adjust such settings and to be able to accurately reproduce a desired setting at a later time. However, the mechanism illustrated in the '568 patent does not provide for the rapid collection and display of measurement data relating to the drag forces set by the operator. Other prior art mechanisms have also not provided integral mechanisms for sensing drag settings and quickly conveying such settings to the camera operator in a unified way. Rather, prior art techniques have generally employed visual mechanical mechanisms that do not provide the level of accuracy, repeatability, and ease of use desirable in the motion picture industry.

Generally, counterbalance measures have been utilized to balance the weight of the camera about the tilt axis. An example of a spring-operated counterbalance technique is described in the '568 patent, previously incorporated by reference in its entirety. Other counterbalance techniques have been employed as well. For example, counterbalances using linear springs or cam and roller architectures have sometimes been employed.

However, prior art counterbalance techniques generally function well only for small to medium tilt angles. While the counterbalance mechanism disclosed in the '568 patent functions over a tilt angle of ±90° and desirably exerts a sinusoidal restoring torque, none of the prior art techniques, including that of the mechanism disclosed in the '568 patent, are adapted and ideally suited for heavier cameras. Many of the cameras in use today for motion picture and television filming work, however, may far exceed 200 pounds in weight. For that reason, a heavy-duty counterbalance mechanism adapted to accommodate the counterbalance loads produced by such equipment is needed.

Additionally, prior art mechanisms for attaching a camera or other equipment unit to a camera head are not suitable for use with heavy equipment. That is, they do not provide sufficient ease of attachment and detachment for cameras that are cumbersome due to extreme weight. For example, a typical sliding dovetail connection requires a user to slide a heavy object along a precise axis while holding the object level until support is achieved. Even systems that permit one side of the dovetail base to drop away for camera removal still require manual intervention by the user to force the dropping side down.

In addition, it is often desirable for a camera operator or film editor to know the position of the camera throughout a shot or sequence in order to reproduce a scene or to coordinate special effects with the actual footage taken. The prior art, however, has not included means by which the camera operator could readily ascertain and thereby reproduce the exact position of the tripod and camera.

Accordingly, it is a general object of the invention to provide an improved camera panhead that smoothly pans and tilts while allowing instantaneous capture and display of camera position and drag setting information. A more specific object is to provide a head that provides the instantaneous electronic capture and display of the camera position and movement.

It is a further object of the invention to provide an improved camera panhead that is able to provide nonlinear counterbalance action for heavy cameras or other equipment throughout a wide range of tilt angles.

It is a further object of the invention to provide a camera head that allows easy and accurate adjustment of the counterbalance and drag settings.

It is a further object of the invention to provide an improved camera head that allows for the natural and uncomplicated mounting and removal of heavy cameras or other equipment to the panhead.

SUMMARY OF THE INVENTION

The invention embodies in general terms an improved camera panhead that provides counterbalance action suitable for heavy cameras or equipment, and that provides instantaneous electronic measurements of head settings and position. The improved counterbalance utilizes a novel dual-tower dual-axis non-linear mechanism to provide sufficient restoring force and integrity to support heavy camera equipment, while still being relatively lightweight. The improved camera head also provides high-accuracy absolute position rotary encoders indexed to each axis of head movement, as well as potentiometer setting detectors indexed to settable adjustments. In this manner, both camera positions and parameter adjustments may be electronically captured, recorded, and displayed to the user.

A conveniently placed electronic display conveys information regarding the current state of the camera head. In particular, a digital LCD graphical user interface is located on the head and displays information relating to the position of the head and the position of the head adjustment settings such as drag and counterbalance settings. The digital display is part of an electronics module that also contains various electrical inputs and outputs. A remote display module may be connected to the electronics module via a cable to remotely display to a user data relating to the head.

A mounting platform situated at the top of the head provides for fast and simple mounting and unmounting of heavy equipment. In particular, a novel dovetail engagement mechanism provides for compressive force by a movable dovetail side during attachment of the camera. However, the novel dovetail engagement mechanism also swings the dovetail side down and away from the dovetail platform during detachment to facilitate easy removal of the camera or other heavy equipment from a dovetail base.

A dutch roll head attachment is mountable upon the mounting platform and is adapted to receive the camera, thus providing an additional axis of camera movement as well as positional information.

An embodiment of the invention comprises a panhead for supporting equipment and providing movement from a vertical position to a tilt position, said panhead comprising, in combination, a tilt housing, a tilt drum defining a tilt axis, said tilt drum being mounted within said housing for rotation about said tilt axis, at least four springs, said springs forming at least two separate pairs of springs, mounted in substantially perpendicular planes to said tilt axis, a common axis disposed substantially parallel to the tilt axis, at least one mount for mounting one end of each of said springs pivotally along a common horizontal axis, said common axis lying below said tilt axis in a vertical plane containing said tilt axis, whereby the end of one spring in each pair of springs coupled to the common axis is mounted between the ends of the other pair of springs coupled to the common axis, the spring pair mountings to the common axis being staggered, and a plurality of mounts for coupling the opposite ends of each pair of said springs to the tilt drum for rotation therewith, said pairs of springs being mounted at an angle to a substantially vertical plane containing the tilt axis when said panhead is in said vertical position, whereby said springs exert a restoring torque when the tilt drum is tilted from said vertical position to said tilt position. An embodiment of the invention further comprises a vertical pan shaft defining a vertical pan axis, and a base housing for mounting said tilt housing on said vertical pan shaft for rotation about said vertical pan axis. An embodiment of the invention further comprises a first integral rotary sensor disposed within the tilt housing and adapted to sense rotation of the tilt drum about the tilt axis and output a first signal indicative of the rotation of the tilt drum about the tilt axis. An embodiment of the invention further comprising a second integral rotary sensor disposed within the base housing and adapted to sense rotation of the tilt housing about the pan axis and output a second signal indicative of the rotation of the tilt housing about the pan axis. An embodiment of the invention further comprises a display unit for displaying a first display related to the rotation of the tilt drum about the tilt axis and a second display related to the rotation of the tilt housing about the pan axis, wherein the first and second displays are derived from the first and second signals respectively. An embodiment of the invention further comprises a roll head mounted to the panhead for rotation of the supported equipment for rotation of the supported equipment about a roll axis, the display unit further comprising an input for receiving a third signal indicative of an amount of roll about the roll axis experienced by the roll head mounted to the panhead, and a third display related to the amount of roll about the roll axis experienced by the roll head, wherein the third display is derived from the third signal.

In an alternate embodiment of the invention comprises a panhead for supporting equipment and providing movement from a vertical position to a tilt position, said panhead comprising, in combination, a tilt housing, a tilt drum defining a tilt axis, said tilt drum being mounted within said housing for rotation about said tilt axis, at least four springs, said springs forming at least two separate pairs of springs, mounted in substantially perpendicular planes to said tilt axis, a common axis disposed substantially parallel to the tilt axis, at least one mount for mounting one end of each of said springs pivotally along a common horizontal axis, said common axis lying below said tilt axis in a vertical plane containing said tilt axis, whereby the end of one spring in each pair of springs coupled to the common axis is mounted between the ends of the other pair of springs coupled to the common axis, the spring pair mountings to the common axis being staggered, and a plurality of mounts for coupling the opposite ends of each pair of said springs to the tilt drum for rotation therewith, said pairs of springs being mounted at an angle to a substantially vertical plane containing the tilt axis when said panhead is in said vertical position, whereby said springs exert a restoring torque when the tilt drum is tilted from said vertical position to said tilt position, a vertical pan shaft defining a vertical pan axis, and a base housing for mounting said tilt housing on said vertical pan shaft for rotation about said vertical pan axis, the panhead further comprising a first integral rotary sensor disposed within the tilt housing and adapted to sense rotation of the tilt drum about the tilt axis and output a first signal indicative of the rotation of the tilt drum about the tilt axis, the panhead further comprising a second integral rotary sensor disposed within the base housing and adapted to sense rotation of the tilt housing about the pan axis and output a second signal indicative of the rotation of the tilt housing about the pan axis, the panhead further comprising a display unit for displaying a first display related to the rotation of the tilt drum about the tilt axis and a second display related to the rotation of the tilt housing about the pan axis, wherein the first and second displays are derived from the first and second signals respectively, the display unit further comprises a plurality of further displays for displaying at least an indication related to the restoring torque exerted about the tilt axis when the tilt drum is tilted from an equilibrium position.

In an alternate embodiment of the invention, a panhead for supporting equipment and providing movement from a vertical position to a tilt position comprises, in combination, a tilt housing, a tilt drum defining a tilt axis, said tilt drum being mounted within said housing for rotation about said tilt axis, at least four springs, said springs forming at least two separate pairs of springs, mounted in substantially perpendicular planes to said tilt axis, a common axis disposed substantially parallel to the tilt axis, at least one mount for mounting one end of each of said springs pivotally along a common horizontal axis, said common axis lying below said tilt axis in a vertical plane containing said tilt axis, whereby the end of one spring in each pair of springs coupled to the common axis is mounted between the ends of the other pair of springs coupled to the common axis, the spring pair mountings to the common axis being staggered, and a plurality of mounts for coupling the opposite ends of each pair of said springs to the tilt drum for rotation therewith, said pairs of springs being mounted at an angle to a substantially vertical plane containing the tilt axis when said panhead is in said vertical position, whereby said springs exert a restoring torque when the tilt drum is tilted from said vertical position to said tilt position, the panhead further comprising a vertical pan shaft defining a vertical pan axis, and a base housing for mounting said tilt housing on said vertical pan shaft for rotation about said vertical pan axis, the panhead further comprising a pan drag assembly for exerting a drag force against rotation of the housing on said vertical pan shaft about said vertical pan axis, the panhead further comprising a tilt drag assembly for exerting a drag force against rotation of the tilt drum, and a display unit for displaying an indication related to an amount of drag force exerted against rotation of the tilt drum about the tilt axis or the tilt housing about the pan axis. In another embodiment of the invention, the panhead further comprises a roll head mounted to the panhead for rotation of the supported equipment about a roll axis, the display unit further comprising a roll display for displaying an indication related to an amount of drag force exerted against rotation of the roll head about the roll axis.

Another embodiment of the invention further comprises a dovetail mount for retaining a removable dovetail rail, the dovetail mount being adapted to secure the removal dovetail rail to a panhead of an equipment supporting device, the dovetail mount comprising: a pair of opposed dovetail sides forming a dovetail track, at least one of said dovetail sides being movable; a movable locking lever; and an actuable coupling mechanism extending between the movable dovetail side and the lever; said locking lever being movable in a first direction for pressing the movable dovetail side toward the opposed dovetail side, thereby retaining the removable dovetail rail, said locking lever being movable in a second direction to move the movable dovetail side away from the opposed dovetail side in a horizontal plane, movement of the locking lever past a threshold point in the second direction further acting to lower the movable dovetail side through the horizontal plane, allowing the removable dovetail rail to be disengaged from the dovetail track. In another embodiment, the actuable coupling mechanism comprises a camming arrangement to lower the movable dovetail side through the horizontal plane.

Another embodiment of the invention comprises a dovetail mount for retaining a removable dovetail rail, the dovetail mount being adapted to secure the removal dovetail rail to a panhead of an equipment supporting device, the dovetail mount comprising: a pair of opposed dovetail sides forming a dovetail track, at least one of said dovetail sides being movable; a movable locking lever; and an actuable coupling mechanism extending between the movable dovetail side and the lever; said locking lever being movable in a first direction for pressing the movable dovetail side toward the opposed dovetail side, thereby retaining the removable dovetail rail, said locking lever being movable in a second direction to move the movable dovetail side away from the opposed dovetail side in a horizontal plane, movement of the locking lever past a threshold point in the second direction further acting to lower the movable dovetail side through the horizontal plane, allowing the removable dovetail rail to be disengaged from the dovetail track, the actuable coupling mechanism comprising at least one movable arm pivotably coupling the locking lever to the movable dovetail side at a first pivot axis, and the camming arrangement comprises a catch and at least one trip lever pivotably coupled at a second pivot axis, said trip lever being disposed to engage said catch as said locking lever is moved past said threshold point in the second direction, said trip lever rotating about said second pivot axis to exert a force on said movable dovetail side to rotate the movable dovetail side about said first pivot axis to lower the movable dovetail side through the horizontal plane. In another embodiment, the trip lever is pivotably coupled to the movable dovetail side.

Another embodiment of the invention a dovetail mount for retaining a removable dovetail rail, the dovetail mount being adapted to secure the removal dovetail rail to a panhead of an equipment supporting device, the dovetail mount comprising: a pair of opposed dovetail sides forming a dovetail track, at least one of said dovetail sides being movable; a movable locking lever; and an actuable coupling mechanism extending between the movable dovetail side and the lever; said locking lever being movable in a first direction for pressing the movable dovetail side toward the opposed dovetail side, thereby retaining the removable dovetail rail, said locking lever being movable in a second direction to move the movable dovetail side away from the opposed dovetail side in a horizontal plane, movement of the locking lever past a threshold point in the second direction further acting to lower the movable dovetail side through the horizontal plane, allowing the removable dovetail rail to be disengaged from the dovetail track, the actuable coupling mechanism comprising at least one movable arm pivotably coupling the locking lever to the movable dovetail side at a first pivot axis, and the camming arrangement comprises a catch and at least one trip lever pivotably coupled at a second pivot axis, said trip lever being disposed to engage said catch as said locking lever is moved past said threshold point in the second direction, said trip lever rotating about said second pivot axis to exert a force on said movable dovetail side to rotate the movable dovetail side about said first pivot axis to lower the movable dovetail side through the horizontal plane, the catch being secured to the movable dovetail side.

Another embodiment of the invention further comprises a dovetail mount for retaining a removable dovetail rail, the dovetail mount being adapted to secure the removal dovetail rail to a panhead of an equipment supporting device, the dovetail mount comprising: a pair of opposed dovetail sides forming a dovetail track, at least one of said dovetail sides being movable; a movable locking lever; and an actuable coupling mechanism extending between the movable dovetail side and the lever; said locking lever being movable in a first direction for pressing the movable dovetail side toward the opposed dovetail side, thereby retaining the removable dovetail rail, said locking lever being movable in a second direction to move the movable dovetail side away from the opposed dovetail side in a horizontal plane, movement of the locking lever past a threshold point in the second direction further acting to lower the movable dovetail side through the horizontal plane, allowing the removable dovetail rail to be disengaged from the dovetail track, the dovetail mount further comprising at least one pair of mating rack and pinion gears secured to the removable dovetail rail and the dovetail track, whereby the position of the removable dovetail rail within the dovetail track can be adjusted by rotating the pinion before fixing the removable dovetail rail to the dovetail track.

Another embodiment of the invention comprises a quickly detachable battery power source including at least one battery having two terminals for powering electric functions of a panhead, the battery power source comprising; first and second leads adapted to be electrically coupled to the battery terminals; a housing for holding at least one said battery, said housing having a first end and a second closed end; and a closure for placement at the first end of the housing after insertion of the at least one battery, such that prior to fixed placement of the cylindrical closure at the first end of the housing, a voltage difference is not measurable across the first and second leads, and a voltage difference is measurable across the first and second leads after fixed placement of the closure at the opening of the housing. In another embodiment of the invention, fixed placement of the closure at the first end of the housing requires application of first force along an axis of the housing, followed by application of a second force along an angular direction relative to the axis of the housing, whereby the closure resists removal forces applied along the axis of the housing. Another embodiment of the invention includes an electronic panhead display package for displaying a readout corresponding to at least one angular displacement associated with a panhead, comprising such a battery power source and further comprising a processing unit and a backup power source, so that if the cylindrical closure is removed from the cylindrical housing, the backup power source will supply electrical power temporarily to the processing unit.

Another embodiment of the invention comprises a method for coupling a battery power source to a panhead to power electrical functions of the panhead, the method comprising the steps of providing a battery power source having a housing and having a first lead disposed at an end face the housing and a second lead extending from a side surface of the housing, linearly advancing the end face into engagement with the panhead, and rotating the battery housing to engage the leads with electrical connections of the panhead.

Another embodiment of the invention comprises a dutch roll head for providing a roll function to a camera, the dutch roll head being remotely actuable by a user, comprising:a roll axle disposed along a roll axis; a motor connected to the roll axle for causing rotation thereof about the roll axis; and a user grip adapted for mounting on a handle, whereby the grip may be used to move the handle; and an electronic interface element mounted on the user grip linked to the motor via an electronic link and adapted to be actuated by said user, whereby when said user actuates the interface element by a given amount, a signal is transmitted via the electronic link to the motor causing the motor to effect a rotation of the roll axle in an amount proportional to the given amount by which the user actuates the interface element. Another embodiment of the invention comprises such a dutch roll head wherein the interface element is selected from the group consisting of a sliding switch, a rotary switch, and a toggle switch.

Additional features and advantages of the invention will be made apparent from the following detailed description of illustrative embodiments, which proceeds with reference to the accompanying figures.

DETAILED DESCRIPTION OF THE INVENTION

Turning to the drawings, wherein like reference numerals refer to like elements, the invention is illustrated as being implemented in accordance with teachings of the invention in a panhead as shown inFIG. 1.FIG. 1shows a perspective view of a panhead1according to an embodiment of the invention. The illustration ofFIG. 1is generalized, and is intended to convey to the reader the general features and usage of the panhead in accordance with this embodiment. The panhead1consists of a base3that is mountable to a tripod or other support, that in turn rests upon the ground or floor. The remainder of the panhead, that is from housing5upward, is pivotable about a pan axis7that runs substantially through the center or central region of the base3. This motion is damped and sensed, as will be discussed hereinafter. Locking lever9is operable to lock the panhead so that it does not move about the upright pan axis7. It will be appreciated that the placement of this lever or any other control is not critical. Thus, for example, lever9may alternatively be located in a symmetric location on the opposite side of the head1.

A housing11covers mechanisms related to the pivoting of the panhead about a tilt axis13, the mechanisms running substantially horizontally through the center or central region of housing11. The motion of the head1about this axis is also sensed and damped as will be discussed hereinafter. Locking lever17is operable to lock the head to prevent movement about tilt axis13.

Situated at the top of the head1are structures to facilitate the mounting of a camera or other equipment to the head1. In particular, a dovetail base19is fixed to the housing11, while a dovetail platform21is fixable to the dovetail base19via two dovetail sides, one of which23is visible inFIG. 1, the other of which is symmetrically situated on the opposite side of the dovetail platform21. Rather than mounting a camera directly to the dovetail base19via the dovetail platform21, it is also possible to mount the camera to another attachment such as a dutch roll head as described herein, which is then mounted to the dovetail base19.

It will be appreciated that the placement of a heavy camera atop the head1will create a significant downward force in the direction of pan axis7when the camera is situated directly over the tilt axis13. It will be further appreciated that any deviation of the center of gravity of the camera from pan axis7will result in an increasing torsional load about tilt axis13as the deviation increases. Thus, when a camera or other instrument supported on the platform21(or a dutch head) is then tilted about the tilt axis13, a significant and nonlinear restoring force is required to counterbalance the camera so that the operator is not required to constantly exert force to prevent the camera from pulling itself downward around tilt axis13. In accordance with an important aspect of the invention, the head1is provided with a heavy-duty nonlinear counterbalance mechanism.

Referring toFIG. 2, the counterbalance mechanism according to an embodiment of the invention is shown.FIG. 2ashows a sectional side view of the counterbalance mechanism taken along tilt axis13, whileFIG. 2bshows a cut-away top view of the mechanism taken along pan axis7, the tilt drum14having been removed. It will be appreciated that the tilt drum14defines a tilt axis about which it rotates. While the structure described herein is novel, the basic principle of operation of the counterbalance mechanism itself remains substantially the same as described in the '568 patent to O'Connor et al., previously incorporated by reference. Accordingly, the function will be described only in overview except for those portions that differ. For a more complete understanding of the geometrical principles involved during use of the head, the reader is invited to read the '568 patent, paying particular attention to the discussion ofFIGS. 6-10.

Referring toFIG. 2a, the lower portion of the panhead can be seen, as well as the dovetail base19for supporting equipment atop the head1. As described in greater detail in the '568 patent, the wiffle trees201,203capture springs205in such a manner as to compress the springs more or less depending upon the position of the base19as the head is tilted. The reader is referred toFIGS. 8-10of the '568 patent for a discussion of the forces in play during tilting of the head. Essentially, the nonlinear deformation of the springs205creates a nonlinear counterbalancing force to counter the nonlinear torsional force applied by the weight of the camera on the head during tilting.

However, for large heavy cameras, such as those weighing 200 pounds or more, the counterbalance force that the springs205must exert becomes immense. This creates a need for very powerful springs, each capable of exerting a restoring force of approximately 1000 pounds or more, but the use of such powerful springs tends to place large loads on the structural components of the head such as the rods211supporting the trees201,203. Additionally, the force required to adjust the counterbalance force by adjusting the position of the common rod213is greatly increased generally in proportion to the increase in spring strength.

The solution of the present invention is to employ strong yet compact compression springs, adapted to meet the large loads imposed, and being disposed in a novel arrangement to avoid damage to other components of the head. In particular, in order to minimize the weight of the finished head, it is desirable to use hollow steel rods211,213, produced from 4130 heat-treatable alloy steel or other high strength steel or alloy. The reason for using hollow steel rods is that other lightweight metals such as aluminum typically do not possess the structural strength of heavier metals such as stainless steel, chrome molybdenum alloys, and other alloys.

Even so, in order to reduce the weight of the head while accommodating the structural loads imposed by the strong springs used, it is desirable to reduce the permissible size of the rods by arranging the spring loading to reduce the exerted rod bending moment. Referring toFIG. 2b, an exemplary wiffle tree arrangement according to the present invention is shown. In particular, the illustrated arrangement is devised to minimize bending moments by minimizing the distance between oppositely acting force centers on the most susceptible elements, i.e. rods211,213.

Two support towers215,217for the common rod213are provided, approximately symmetrically placed on rod213, extending downward in the direction of pan axis7. It will be appreciated that the dual tower arrangement is also particularly suitable for use in an application such as this, where extremely high force springs are utilized. The bending moment applied to the common rod213is reduced by providing the dual support towers215,217, thus reducing the necessary size and weight of the common rod213. To readily adjust for equipment of varied weights, these towers are vertically adjustable to adjust the position of the common axis or rod213. This way, the operator may adjust the counterbalance force provided (according to the basic principles set forth in the '568 patent, already incorporated herein by reference in its entirety).

The spring assemblies are arranged as shown, so that the support towers are placed between oppositely extending wiffle tree and spring assemblies, which are disposed at an angle with respect to pan axis7. Additionally, the wiffle trees and support towers are disposed in a relationship that minimizes the bending moments, and, therefore, stresses along the shafts. More specifically, the wiffle tree pairings are identical, rather than mirror images of each other across the center of the head along the tilt axis as in the prior art. That is, the wiffle trees are disposed in a staggered fashion as opposed to symmetrically about a central support tower, as disclosed in the '568 patent. In this way, the two central wiffle tree assemblies place the greatest bending load on their respective wiffle tree support rods211. However, unlike the prior art, the other wiffle tree assembly on each support rod211provides minimal additional bending load because each is placed adjacent a support point, i.e. end wall207or end wall209. With respect to the loads experienced by common rod213, the bending loads are also minimized by the illustrated configuration. In particular, lower wiffle tree supports203are placed so as to minimize the distance between them and any adjacent support points such as support towers215,217or end walls207,209. In addition, the close spacing of opposing lower wiffle tree supports203minimizes the local twisting moment resulting from pairs of oppositely directed horizontal force components applied on rod213by adjacent lower wiffle tree support pairs. In other words, the staggered positioning of the wiffle tree supports201,203along the respective support rods211and common rod213minimize the resulting bending moments exerted by the two centermost wiffle tree supports201,203.

Note that the foregoing discussion describes a preferred arrangement for two pairs of spring assemblies used in counterbalancing, however, the two pairs of spring assemblies may alternatively be arranged in another configuration. Exemplary alternative configurations are shown inFIGS. 12 and 13of the '568 patent (for two spring assemblies) already incorporated herein, and are described in the related discussion in the '568 patent. Given the disclosure herein, one of skill in the art will appreciate that the same mechanisms may be adapted for the use of two pairs of spring assemblies.

FIG. 3illustrates an exemplary mechanism by which the support towers215,217ofFIG. 2may be adjusted upwardly and downwardly along pan axis7without the application of undue force by the operator. In particular,FIG. 3illustrates a partial cross sectional view of the panhead at line A taken along pan axis7ofFIG. 2a. It can be seen that support towers215,217are centered on circular gears301,303. Respective threaded shafts302,304fixed to each of gears301,303extend perpendicular to each gear's major plane and extend threadably into each of support towers215,217. Thus, a turning of the gears301,303results in a raising or lowering of the support towers215,217. Even though this relationship provides a certain leverage advantage depending upon the thread pitch of the threaded shafts302,304fixed to the circular gears301,303, the strength of the springs205is such that greater leverage may be needed by many human operators. Accordingly, the gears301,303are driven and coordinated via respective worm gears305,307, attached to a common shaft309. Thus, in accordance with an important feature of the invention, the rotation of the common shaft309results in the substantially identical, simultaneous movement of the support towers215,217. A further gear reduction is provided by a spur gear311attached to shaft309and indexed to a pinion gear (not visible in this view). One exemplary gearing arrangement will be discussed in greater detail below with respect toFIG. 7.

The pinion gear is attached to a common shaft315that also carries a handle313that may be manipulated by an operator. The handle also preferably further includes an exposed socket on a common axis with the shaft315, allowing the handle to be alternatively turned via an electric screwdriver or other rotary tool. This feature may aid the operator when there is insufficient time to turn the handle by hand the required number of turns to provide the necessary counterbalance.

It will be appreciated that rotation of the handle313will cause a rotation of gears301,303, and a subsequent coordinated raising or lowering of support towers215,217. In turn, the raising or lowering of the towers compresses the springs205to a greater or lesser degree, providing varying degrees of nonlinear counterbalance force to counter the tilting of the head about tilt axis13.

To provide a third degree of movement and adjustment, a dutch roll head may optionally be used in conjunction with the panhead. A dutch roll head rotates about a third axis, typically referred to as the roll axis. A roll axis is one that is substantially parallel with the camera sight line axis, although the two need not be co-linear.FIG. 4illustrates a roll head assembly401. The roll head401comprises a base403fixable to the top of the panhead previously discussed by for example a dovetail mount, and pivotally fixed to roll platform405at roll axis407. Roll axis407preferably coincides with camera axis409, although it is sufficient that both axes are simply substantially parallel.

According to an important feature of the invention, however, the center of gravity of the mounted camera and roll platform405is disposed along the roll axis407. In this way, the equipment balance of the head1remains unaffected by the roll of the equipment mounted on the dutch roll head401. In order to facilitate adjustment of the height of platform405, both to assure necessary clearance with the base403and to place the center of gravity of the platform405and camera along the roll axis407, the platform405is movable up and down in the direction of axis415. The base403is illustrated as being slotted to permit rod413to be moved vertically. However, other techniques for allowing vertical movement may also be used. For example, the platform405may be vertically movable with respect to rod413. In any case, the movement of the platform405alone or the platform405and rod413is linearly constrained, as along a dovetail mount or along a track made of two rods.

While alternative mechanisms may be used to allow vertical movement of the platform405, a rack and pinion, screw, or other suitable mechanism is preferably employed to reduce the force needed to adjust the position of the camera and platform405. Such mechanism may be hand-operated, such as via a crank or other actuator. Alternatively, the mechanism may be motorized, such as thru the use of an electric motor geared to controllably alter the vertical position of the camera and platform405, as will be appreciated by those of skill in the art. An exemplary geared vertical adjustment mechanism is illustrated inFIG. 3for adjusting the counterbalance force, and a similar mechanism can be used for any other vertical adjustment such as for adjustment of the roll head. Additionally, a lock417is provided so that the platform405may be fixed in the desired position. The lock may employ compression of dovetail sides, or may use any other mechanism such as a setscrew with a knob head.

A handle411is preferably fixed to platform405via shaft413, the shaft413being coaxial with roll axis407and usable to pivot the platform405about the roll axis407. Within base403, several mechanisms are preferably attached to shaft413. In particular, it may be desirable to provide an adjustable counterbalance mechanism on shaft413to laterally counterbalance the camera weight using the same principles discussed above to provide counterbalance on the tilt axis. Such counterbalance will, however, typically not be required if the camera center of gravity is placed as described above. Additionally, a drag mechanism is preferably indexed to shaft413within base403so as to allow for smooth camera movement about the roll axis407. These elements will be discussed in greater detail hereinafter. The base403may be fixed to the panhead using any suitable mechanism, but it is preferable that attachment be by way of the dovetail platform to be discussed in greater detail below.

The degree of roll attainable depends upon the dimensions of the camera, in that interference between the camera and the base403will determine the limits of travel. Base403preferably exposes other controls usable to affect the roll behavior of the camera. In particular, such controls preferably include a lock417to prevent roll movement of the camera about the roll axis, and a drag adjustment419to adjust the amount of drag about the roll axis407. A mechanical drag indicator421may also be exposed on base403, and/or an electrical output may supply the drag information along with counterbalance adjustment information if counterbalance is used, and encoded roll position information. If counterbalance is used, base403preferably also exposes a counterbalance adjustment control as discussed with respect to the tilt axis counterbalance mechanism.

An alternative dutch roll head arrangement is shown inFIGS. 4b-d. As with the previously discussed embodiment, a base425is provided for attachment to a head as described herein or otherwise. The base comprises or is attachable to a first socket427for receiving a horizontal support tube429. A second socket431also receives horizontal support tube429. Each of sockets427and431are fixable in relation to horizontal support tube429via a clamping action facilitated by bolts433and435respectively, or otherwise. Second socket431has a perpendicularly oriented third socket437fixed thereto for receiving a perpendicularly oriented vertical support tube439. A clamping bolt (not shown) is usable to fix the vertical support tube with respect to the third socket437, in a similar fashion as bolts431and433.

In order to further couple a roll head support441to the base425, a fourth socket443is secured to the roll support441and fixed atop the vertical support tube439via the fourth socket443, and via a clamping action provided by a clamping bolt445. The roll head support441rotatably supports an axle447having a roll handle449optionally coupled thereto on one side. The handle449may be disposed in a hole in axle447and fixed in place via a set screw451, although other attachments are envisioned. On the other side of the roll head support441, the axle447is attached to a roll platform453, to which is attached, via screws or otherwise, a camera base455. A camera457is mounted to the camera base455. It will be appreciated by those of skill in the art that dutch rotation or roll of the roll platform453, camera base455and the camera457will occur about the axis461defined by axle447. In this embodiment, an axis459including the center of gravity of the camera457, the camera base455and the platform453is conveniently illustrated as coinciding with the sight line459of the camera. Thus, those of skill in the art will appreciate that it is desirable to align the axis459, which includes the center of gravity, and, here, the sight line, with the dutch rotational axis461.

FIG. 4billustrates a possible initial mounting position of the camera and the elements of the dutch head before adjustment of the roll axis.FIGS. 4c-dillustrate further adjustments to better align the axis of the center of gravity459of the camera (about which no gravitational tilt moment is exerted) with the roll axis461about which axle447rotates. As shown inFIG. 4c, the roll platform453is first raised vertically so that the central gravitational axis459of the camera substantially coincides with the roll axis461of the roll head441. This adjustment may be allowed and then fixed via a set screw or other means, fixing the roll platform453in relation to the axle447. Subsequently as shown inFIG. 4d, the camera is lowered (to attain a lowest possible center of gravity for stability) while maintaining the registration between the central axis459of the center of gravity and the camera and the roll axis461of the roll head assembly. This is done by loosening the clamping bolt (not shown) associated with socket437and lowering vertical support member439until further substantial adjustment would cause interference between the roll platform453and any other member of the dutch roll head or of a pan head to which the dutch roll head may attached. After adjustment, the clamping bolt associated with socket437is retightened. Note that the alternative dutch roll head shown inFIGS. 4b-dpreferably embodies all the same tilt locks, sensors, indicators, outputs, drag adjustment mechanisms, etc. as the head shown with reference toFIG. 4a.

Further, note that the vertical adjustment mechanisms described with respect toFIG. 4amay likewise be applied to the roll head arrangement shown inFIGS. 4c-d. For example, the vertical movement of the platform453and base455, and accordingly the camera457may be geared due to the extreme weight of the camera457, and such gearing may be actuated either manually, such as via a crank, or automatically such as via a geared electric motor. By way of further example, a gearing mechanism that can be either manually actuated, or driven by a power screw driver or the like may be provided. Alternately, a drive motor may be provided. It will be appreciated that the various mounting and adjustments may also be provided in accordance with the spirit and teaching of the invention.

An alternative roll platform adjustment mechanism is shown inFIG. 4e. In particular, the roll platform461, which is pivotable about the roll axis465at axle463, is vertically adjustable via a slide467retained within a rectangular tube469. The fit between the slide467and the tube469is preferably such that the slide cannot move substantially in lateral dimensions, but may move vertically within the tube469for adjustment. Additionally, as with the other embodiments, the camera platform471is adjustable fore and aft, such as in a direction parallel to the roll axis465, and is also adjustable laterally, or side-to-side. In this manner, the center of gravity of the camera and platform may be adjusted so that they do not exert a roll moment or a tilt moment. Such fore and aft and lateral adjustment is preferably, but not necessarily, effected by way of a dovetail slide and mount disposed along each direction. Once the vertical, fore and aft, and lateral positions of the camera are set, the movement of the platform in each dimension is preferably lockable so that the balance of the camera package does not change during use.

Referring now toFIG. 17, an optional motor drive and actuator for the dutch roll head is shown schematically. In this embodiment, a user actuated actuator grip1701is mountable on a handle, such as a pan handle, usable to pan the camera on the pan head as described elsewhere herein. The grip1701may be mounted by clamps, friction fit, or otherwise. For example, the grip may have a cavity1703that cooperates with the exterior of a tubular handle to secure the grip1701to the handle.

The grip1701is electrically connected to a motor1705. A switch1707on the grip1701allows the user to actuate the motor in either direction, and preferably at a rate that is proportional to the user induced displacement of the switch1707, such as by sliding, toggling, or rotation. The motor1705is geared to an axle1711at the roll axis, such as axle413ofFIG. 4a, such that the actuation of the motor1705causes the roll platform, and hence the camera package, to roll about the tilt axis. The gearing of the motor to the tilt axle may be by belt drive, chain drive, or geared drive, and preferably should use reduction gearing both to allow the motor to more easily adjust the roll, and to allow greater precision of movement. Note that the other functions of the roll head, such as position measurement through a rotary encoder1709, are preferably employed within this embodiment as well.

Using the actuator grip as described above, a user can pan, tilt, and roll the camera package using only one hand. This provides a smoother camera operation and eases the task of the camera operator. Additionally, the user's other hand can then be used to actuate other desired functions, such as drag adjustment, axis locks, and so on.

The mechanisms for adjusting the drag on each axis will now be discussed. As mentioned previously, providing a certain amount of drag on a given axis of rotation will tend to smooth the movement about that axis, eliminating camera overshoot and unsteadiness. Because cameras and operators differ greatly, it is desirable to provide an adjustment mechanism whereby the amount of drag may be preset or modified. The '568 patent, already incorporated by reference in its entirety, discloses the basic principle of viscous drag mechanisms, and the reader is referred to that patent for a full discussion of such mechanisms. The present invention utilizes the basic principles set forth in that patent, but utilizes an improved mechanism to actuate the drag sectors.

Referring toFIG. 6, a schematic view of an exemplary viscous drag mechanism601is shown. The drag assembly601includes a number of drag sector assemblies603and a drag disc assembly605. The drag sector assemblies603are mounted so as to be movable linearly along a radius of the drag disc assembly605. The individual stacked discs619of the drag disc assembly605are fixed to a shaft607. In this way, when the shaft607rotates, the drag disc assembly605rotates as well.

The individual elements619of each of the drag sector assemblies603are appropriately fixed relative to each element619in a given drag sector assembly603by rods and spacers620or other appropriate mechanism. The individual elements619in turn are interleavably related to the drag disc assembly605. In turn, the drag sector assemblies603are actuated in a coordinated fashion by gears609which are manipulated by a user through a knob621or other mechanism. Thus, as the user turns the adjustment knob621, the drag sector assemblies603become symmetrically more or less interleaved with the drag disc assembly605depending upon the direction in which the knob621is turned. Note that although a direct connection is shown between knob621and gear609, any alternative actuating arrangement may be used. For example, the knob621may drive a worm, which drives a worm gear, which is geared to gear609.

The spaces between stacked discs617of the drag disc assembly605, between the stacked individual elements619of the drag sector assemblies630, and between the stacked discs619and individual elements619are filled with a viscous fluid. A greater level of interleaving will create a stronger viscous drag on the drag disc assembly605and hence on the shaft607. Likewise, a lesser degree of interleaving will lessen the amount of drag associated with the rotation of shaft607. The reader is referred to the '568 patent and U.S. Pat. No. 3,822,769 to O'Connor, hereby incorporated by reference in its entirety for all that it teaches, for a fuller discussion of the drag-producing interaction and environment.

The gears609are coordinated by interceding gears, chain and cogs, or other suitable mechanism for coordinating their movement, so that the assemblies603move symmetrically with respect to disc605. Although two drag sector assemblies603are shown for clarity, any number of such assemblies may be employed. In another embodiment, only one such drag sector assembly and one such disc605are provided for each axis. In this presently preferred embodiment, the drag sector assemblies603each comprise23sector pieces619with22spacer elements (see620) located between the sector pieces619, and each disc605comprises22disc elements617spaced apart by21spacer elements (not visible) along shaft607.

Having described the mechanical aspects of the invention in detail above, the electrical features of the panhead according to the invention will now be discussed. In accordance with an important feature of the invention, the position of the panhead1with regard to the degree which the mounted equipment is rotated about the pan axis7, and/or tilted about the tilt axis13, and/or the dutch head roll axis461may be directly read by the user. In this way, a given shot may be recorded or read for later duplication, for example, or for special effects applied based upon a given position of the equipment. In overview, the electrical features provided facilitate the measurement and reporting of camera position and adjustment settings. Other electrical features such as backlighting for camera level indicators are also preferably provided. In order to electronically sense the position of the panhead1, rotary encoders are positioned within housings5and11(and dutch roll head, if utilized), as will be discussed more fully hereinafter. The sensed positions are converted to electronic data digitally displayable on graphical user interface panel25(as shown, for example, inFIG. 1). The electronic module27of which the graphical user interface25is a part also preferably comprises buttons and switches usable to interact with the module to control features of the display or other features such as head level backlights, as well as electrical inputs and outputs.

FIG. 5illustrates an exemplary graphical user interface for allowing an operator to observe measurement data and to affect the operation of the electronic features. Note that all measurement data may also or alternatively be fed to the camera or image storage device itself, so that the camera position will be stored in direct association with the captured image at any point in time. Panel501is part of electronics module503. In addition to the panel501, the electronics module503also exposes electrical contacts, preferably LEMO connectors, for providing and receiving electrical power and signals. Within module503are standard electrical circuits to receive, convey, and process information to provide the indicated outputs and displays.

More specifically, panel501comprises a power button or switch505for turning on and off the power to the electronics module503. Another button or switch507is operable to turn on and off certain lights. Such lights may be, for example, back-lights, such as LEDs used to enhance the readability of liquid bubble level devices mounted on the head which are usable to level the camera on one or more axes.

Further, panel501also comprises display elements related to the position of each axis as well as the drag setting for each axis and any counterbalance setting for each axis. Thus, for example, row509displays information related to the roll axis, such as head angle511on the roll axis, drag setting513for the roll axis, and counterbalance setting515for the roll axis. A reset button517is preferably provided for each axis to allow the operator to set the current angle as zero, so that subsequent angle measurements may be taken from that point. The display rows for the tilt519and pan529axes expose the same features and functionality, keeping in mind that a given axis may omit certain features. For example, it will not be typical to provide a counterbalance or associated counterbalance adjustment reading for the pan axis, but such may be provided.

The LEMO connector ports exposed by the electronics module preferably include a 5 volt auxiliary power input521, a computer output523, a remote output525, and a roll head input527. Although batteries typically power the electronics module, the 5 volt auxiliary power input521allows the operator to optionally power the electronics module via an external 5 volt DC power source. The computer output523provides the information collected and displayed in the form of a digital data stream to be received by a separate computer through a serial port or otherwise, so that the positions and settings of the head may be tracked and stored in the computer. The remote output525outputs head position and setting data in a digital or analog form usable by a remote display module. This function allows the operator to attach a remote display module to the remote output525via a cable and to place the remote display module in a location where the operator may conveniently view and/or record all or some of the data available on the panel501. For example, the operator may place the remote display module adjacent to the camera eyepiece via an adhesive or mechanical connection for convenient and instantaneous viewing of head data.

While those of skill in the art will readily appreciate how to configure the circuitry of the electronics module to provide the desired behavior, certain features will be expressly set forth for the convenience of the reader. The electronic components within the electronics module may be placed on separate circuit boards, but it has been found that the use of a single dual sided circuit board is more compact and robust. Furthermore, it is desirable to backlight the panel501. It has been found that an ideal way to provide such backlight is to illuminate the ends of a plurality of fiber optical cables, and terminate the non-illuminated ends of such cables at the back of the LCD display that provides the display information at panel501. While the electronics module may be mounted on any part of the head, it has been found that the most convenient location for mounting the module is on the main body above the joint between the stationary base3and the housing5, as illustrated inFIG. 1.

In order to sense the position of the drag sector assemblies603, a potentiometer611is associated with the gears609. In one exemplary arrangement, a gear615is fixed to the shaft613of the potentiometer611. This gear615mates with one of the gears609so that rotation of gears609causes a rotation of the shaft613of the potentiometer611. In this way, the resistance exhibited by the potentiometer611gives an indication of the current position of the drag sector assemblies603, and hence of the level of drag currently experienced by shaft607. In another embodiment, the shaft613of the potentiometer is directly attached to the shaft of a gear609, providing a corresponding rather than simply proportional reading. The electrical outputs of the potentiometer611are supplied to the electronic module503, for use in deriving a digital representation of the current drag.

The electronic module503also comprises two potentiometer adjustments for each drag assembly in order to adjust the indication of drag given so that it travels from at or near0% for the minimum amount of drag applied, to at or near 100% for the maximum amount of drag applied. In particular, as those skilled in the art of electronics will appreciate, one factory settable potentiometer is provided to adjust the percentage indicated when the drag sector assemblies603are minimally interleaved, while a second factory settable potentiometer is provided to adjust the slope of the percentage indicated as a function of the amount of interleaving. In this way, the percentage of drag indicated on panel501can be adjusted so that minimal interleaving yields a reading at or near 0% while maximum interleaving yields a reading at or near 100%.

A drag mechanism such as that described above is placed on each axis, so that the shaft607is rotated coincident with rotation on the relevant axis. Likewise, the drag adjustment setting on each axis is relayed to the electronic module503and is displayed in the appropriate location on the panel501.

The remaining mechanisms usable to collect data for display on panel501will now be discussed in greater detail. Turning first toFIGS. 3 and 7, gears301,303are driven via respective worm gears305,307, attached to a common shaft309, and a further gear reduction is provided by a spur gear311attached to shaft309and indexed to a pinion gear. Referring toFIG. 7, a portion of the above gearing arrangement is shown in greater detail. Like numerals indicate like components, i.e., elements709,711,713, and715ofFIG. 7correspond to elements309,311,313, and315ofFIG. 3.

The gearing arrangement ofFIG. 7provides for an electronic reading of the counterbalance position in the following manner. When knob713is rotated, in turn rotating pinion717and consequently spur711, the counterbalance support towers215,217are raised or lowered accordingly, adjusting the degree of counterbalance applied. At the same time, worm gear719fixed to common shaft715is rotated. This causes mating gear725, fixed to the shaft723of potentiometer721, to rotate as well, changing the resistance of the potentiometer721. The leads of the potentiometer721are supplied to the electronic module503in order to give an indication of counterbalance applied on the relevant axis. Each axis that is counterbalanced has an associated potentiometer for measuring the counterbalance position as, for example, described above, and a corresponding display is provided at panel501. As described above with respect to the calibration of drag position indication, each position measuring potentiometer is associated with two calibration potentiometers in the electronic module503, usable to calibrate the indication of counterbalance displayed on panel501.

Within an embodiment of the invention, the position of the head itself is measured and displayed to the user via panel501. In this case, it is desirable to use precision rotary encoders rather than simple resistance measurements because greater accuracy may thus be obtained. Exemplary rotary encoders are commercially available. For example, the High-Sensing Accuracy Optical Photo Interpreter, part number GP1A35RV, sold by SHARP ELECTRONICS may be used to encode the movement of an appropriately slotted disc.FIG. 8schematically illustrates the basic configuration of a rotary encoder in use. An encoder disc801is attached to a shaft or other rotation center of interest so that the disc rotates when the rotation center rotates. Typically, the rotation center and the disc801are arranged to remain in a fixed angular relation to one another, although the disc may also be geared up or down to the rotation center of interest. The disc is perforated with slots803that are typically approximately several thousandths of an inch wide and deep. For example, the slots803provided with the GP1A35RV are 2 thousandths of an inch wide and 2 thousandths deep, corresponding to the axial thickness of the disc at the location of a slot.

A pick-up805having a slot807is situated such that the sides809,811of the slot are in a straddling relationship with the disc801. One or more light sources such as LEDs or laser diodes reside within one of the sides809, while one or more light detection devices such as photodiodes or other devices reside in the other side811. The light source and light detection devices are situated so that light from a light source in side809passing through a slot803is detected by a light detection device in the other side811. In this manner, the motion of the disc is detected electronically and an indication of the motion is transmitted on leads813. It is preferable that the disc801and pick-up805combination selected also detect the direction of movement of the disc801. In addition, although the preferred encoding mechanism operates via light transmission, other systems, such as those that operate using reflectance rather than transmission may also be used. Also, the described encoders are absolute encoders as are preferable for best accuracy. However, other types of encoders such as relative encoders may also be used alternatively.

An encoder disc/pick-up combination such as that described above is preferably placed on each axis of movement for which it is desired to display position information. Preferably, position information is displayed for each axis, i.e. the roll, tilt, and pan axes.FIG. 9shows a schematic cross section of a panhead according to an embodiment of the invention in the plane defined by axes7and13ofFIG. 1, at the level of axis13. Housing901and shaft903define a first annular cavity907centered about shaft903, while housing901, endplate905, and shaft903define a second annular cavity909centered about shaft903.

The first annular cavity907contains an adjustable drag mechanism as discussed with respect toFIG. 6. In particular, an annular drag disc assembly915is fixed to shaft903so as to rotate therewith, while one or more drag sector assemblies917are fixed with respect to the housing901except that they may be adjusted along a radius of axis13. Adjustment of these drag sector assemblies917affects the drag associated with the rotation of shaft903in the manner described with respect toFIG. 6.

A slotted encoding disc911such as the disc801ofFIG. 8resides within cavity909, being fixed upon and co-axial with shaft903. A pick-up919such as pick-up805ofFIG. 8is situated within cavity909as well, being fixed to housing901so as to straddle encoding disc911as the disc rotates. Shaft903is also fixed to the tilting components of the panhead and defines the axis of tilting.

Accordingly, as the camera is tilted, in turn tilting the tilting components of the head, shaft903rotates in registration with the camera, causing disc911to rotate as well. As disc911rotates, the slots of the disc alternatingly pass and block light within the pick-up909, creating an electrical signal indicative of the motion of the camera about the tilt axis13. As discussed above, this signal is conveyed via electrical leads to the electronics module913, corresponding to module503ofFIG. 5, which then interprets and displays the information as a percentage of the range of available tilt motion. Note that the user may use the reset button for a given axis such as element517inFIG. 5, to set the current camera position as the zero position with respect to which future positions may be measured.

Note that the various cavities defined within the head and roll head may be changed, so that for example, more of the cavity is defined by one piece than by another, and so on. The only matter of consequence is that such a cavity somehow be defined. Also, note that the relation between the cavities907,909need not be as shown. For example, the cavities, and associated elements, may be disposed on opposite sides of the head, rather than on the same side, such that one end of the axle903is associated with the drag mechanism, while the other end of the axle903is associated with the rotary measurement mechanism. Similarly, a tilt brake and tilt lock if used may be disposed at whichever end of the shaft903is convenient, and need not be on the same side as each other.

In a similar fashion, the position information for the other axes is measured and conveyed to the electronics module913for display.FIG. 10is a cross sectional view of the panhead taken in a plane defined by axes7and13, viewed at the level of line29.FIG. 10schematically illustrates an exemplary position sensing mechanism for measuring the position of the camera about the pan axis7. In particular, the base1001is fixed relative to a tripod or other support, while the upper housing1011which supports the remainder of the panhead is rotatably disposed upon the base1001and coupled thereto via a large bolt1019and washer assembly received in a channel in the upper housing1011.

A plurality of bearings1013,1015,1017are preferably employed to minimize the friction of rotation and to bear the considerable weight of the camera and the upper portion of the head, all of which can rotate about axis7. The bearings1013may be any suitable type, such as Timpkin tapered bearings, adapted to support both axial and radial loads. Bearings1015are preferably disposed to bear axial load associated with the central axle attachment between the upper housing1011and the base1001. Suitable bearings for this purpose include any bearing capable of bearing the magnitude and direction of stress applied, such as Torrington thrust bearings. Bearings1017are situated so as to bear radial loads between base1001and the lower part of upper housing1011. Note that the bearings1015and1017provide a balancing load for the preloaded the tapered bearings1013in the illustrated arrangement. As will appreciated by those of skill in the art, any other suitable number, type and arrangement of bearings may be used instead of the illustrated configuration.

The base defines two annular cavities1021and1023. The first annular cavity1021contains an adjustable drag assembly1003similar in structure and operation to that described above with respect to the tilt axis, the adjustment position of which is measured and displayed as described above. Thus, the cavity1021additionally contains a suitable viscous fluid, such as one of the many silicon-based fluids familiar to those of skill in the art. The second annular cavity1023contains an encoder disc1025and pick-up1009, operating in substantially the same manner as described above with respect to the tilt axis, to measure and relay the pan axis rotation position for display to the user. Note that in the illustrated embodiment, the pick-up1009rotates with the upper housing1011, while the encoder disc1025remains fixed relative to the base1001. However, those of skill in the art will appreciate that appropriate relative motion may also be achieved by fixing the pick-up1009relative to the base and allowing the disc1025to rotate with the upper housing1011.

Note that a pan axis lock may also be employed to lock the rotation of the upper housing1011relative to the base1001. This generally requires a moving locking piece fixed to the housing1011and a stationary locking piece fixed to the base1001. Locking of the pan axis is effected by locking the moving and stationary locking pieces together. Typically, one locking piece will be a disc and the other a disc clamp or other locking mechanism.

FIG. 11is a cross sectional view of the roll head attachment taken in a plane defined by axis407and vertical axis421inFIG. 4a. Note that although not shown in detail in this figure, the camera is preferably adjustable both fore and aft and side to side, so that the center of gravity of the camera exerts neither a roll moment nor a tilt moment. The adjustments may be made by way of sliding dovetails and dovetail mounts or otherwise, as will appreciated by those of skill in the art. The housing1101, corresponding to housing403, preferably contains a damping mechanism and a position encoding mechanism, and may also contain a counterbalance mechanism. In particular, a first annular cavity1103contains an adjustable drag assembly1105similar in structure and operation to that described above with respect to the tilt axis, the adjustment position of which is measured and displayed as described above. A second annular cavity1107contains an encoder disc1109and pick-up1111, operating in substantially the same manner as described above with respect to the tilt axis, to measure and relay the roll axis rotation position for display to the user.

The housing1101optionally defines a third annular cavity1113, containing an adjustable counterbalance mechanism, preferably of the design described above or alternatively as described in the '568 patent. If a counterbalance mechanism is employed to counterbalance the camera about the roll axis, its setting is preferably detected, relayed and indicated to the user as described above with respect to the tilt axis. Note that since the roll head attachment is optional, the electrical signals relating to the damping, counterbalance, and position of the roll head are carried by a separate cable having a male LEMO connector to be plugged into port527of the electronics module503. Note that the aforementioned features of the dutch roll head are preferably also included in an embodiment as illustrated inFIGS. 4b-d.

As discussed above, the electronic features of the panhead typically receive electrical power from a portable battery pack that is affixed to the head or to the tripod or other support. An exemplary construction for the battery pack is illustrated in cross sectional view inFIGS. 12aand12b.FIG. 12ashows the battery pack completely assembled whileFIG. 12bshows the battery pack completely disassembled. The battery pack is constructed of three mating pieces, a battery holder1201, a first top1203and a second top1205. The battery holder1201and the first top1203are made primarily of electrically nonconductive material such as plastic, while the second top1205is made primarily of electrically conductive material such as aluminum. The battery holder1201contains a bottom contact1207for contacting a bottom battery1209shown in outline inFIG. 12a. The bottom contact1207is electrically isolated from the battery holder1201, but is in electrical contact with pin1211via a wire, not visible in these illustrations, when the battery pack is assembled as inFIG. 12a.

The pin1211in the first top1203serves to provide electrical contact between the bottom contact1207and the body of second top1205. A central contact1213in first top1203makes electrical contact with the positive end of the series of batteries within holder1201when the pack is assembled as inFIG. 12a. In turn a central contact1215in second top1205makes electrical contact with the central contact1213when the pack is assembled as inFIG. 12a. A spring1217allows for varying tolerance of the placement of the second top1205with respect to the first top1203. In this manner, the negative or ground voltage of the batteries in the pack is exposed to the panhead via top1205, while the positive voltage is exposed via contact1215. Note that contact1215is electrically isolated from top1205.

The fit and function of the battery pack are illustrated in perspective view in FIG.13for the convenience of the reader. Elements1301,1303,1305,1311,1313, and1315correspond to elements1201,1203,1205,1211,1213, and1215respectively ofFIGS. 12aand12b. It can be seen that the battery pack described herein allows a user to quickly change batteries in two different ways. In particular, the user may rotate and pull the holder1301to detach it from the first and second tops1303,1305. Once the batteries in the holder are exchanged for fresh batteries, the user may push and rotate holder1301to reassemble the battery pack. Alternatively, the user may push and rotate both the holder1301and first top1303, disengaging them as a unit from second top1305. In this manner, another assembled holder and first top may replace the removed unit to provide fresh electrical power. Preferably, the battery pack is assembled to a panhead using the same steps of linearly advancing the battery pack toward the panhead, and axially rotating the battery pack to make the electrical connections. While the holder1301and first and second tops1303,1305are illustrated as cylindrical in shape, it will be appreciated that alternate shapes may be provided.

Note that in either manner of changing out the battery pack from the panhead, power to the electronics module will be interrupted momentarily. For this reason, it is desirable that the electronics module incorporates a capacitor or other electrical energy storage device to provide a short period, such as thirty seconds, of reserve power during battery change. While the battery pack is preferably adapted to accommodate 2 “C” size cells, any other number and size of cells may equivalently be used.

Because the panhead and related components as described herein are generally intended for use with heavy cameras or other equipment, according to another feature of the invention, an improved mechanism for mounting the camera to the panhead is provided. In particular, it is difficult and inconvenient to be forced to slide a heavy camera or roll head mounted on a dovetail platform completely out of a dovetail base before being able to remove it. Even with dovetail bases that would allow a dovetail side to be forced down to permit camera removal, the operator is required to manually force the side down. Unfortunately, clearances are generally such that this is often difficult or impossible.

In an embodiment of the invention, a novel dovetail base is provided that allows an operator to automatically lower one dovetail side by simply moving a lever.FIG. 14shows a perspective view of the novel base1401, with a dovetail platform1403mounted. In operation, the dovetail rail assembly or platform1403is mounted to the bottom of the camera or roll head via screw holes1405, and is then mounted on the dovetail base1401by being compressed between dovetail sides1407shaped to mate with the platform1403. A lever1409is provided and is adapted to compress the dovetail sides1407when pushed in one direction B, and to uncompress the dovetail sides1407and then drop one of sides1407when pushed in the other direction A. The platform1403is indexed to the base1401via a rack and pinion mechanism to be more fully described below. Note that screw holes1411are used to attach the rack to the underside of the platform1403.

FIG. 15shows a schematic bottom view of the platform1401, including one dovetail side1501(see also1407inFIG. 14). This view is provided so that user may understand the mechanism by which the dovetail sides are pressed together. Manipulation of lever1509can be used to either cause dovetail side1501to move toward and mate with dovetail platform1503, or to cause dovetail side1501to move away and downward from dovetail platform1503. According to the presently preferred embodiment, one dovetail1501of the platform moves to allow placement of the dovetail platform1403, as explained herein, while the dovetail1407along the opposite side of the platform1403remains stationary. In this way, the user simply places one edge of the dovetail platform1403underneath the stationary dovetail1407, and then activates the opposite dovetail1501to clamp the platform1403in position.

In particular, as lever1509is pushed in a clockwise direction, it exerts a pull force on first link1521, pivoting lever1523, to which it is hinged, about pivot1525, thus exerting a leveraged pull force along dogbone1527, which is hinged to lever1525. Dogbone1527in turn pulls on and rotates link1529clockwise about pivot1531. This motion causes symmetrical pulling motions by side pieces1535and1533. With the left portion of the assembly as illustrated, the movement of dogbone1527causes link1529to pivot about pivot point1531, causing a clamping or downward motion as viewed on side piece1535via short link1537. This clamping motion is transmitted to the opposite side piece1533of the dovetail side1501by link1545, which causes link1563to rotate about pivot1543and place a downward clamping force on side piece1533via short link1539. In this way, the rotation of the lever1509clockwise will compress as dovetail side1501exerts a force against dovetail platform1503, locking the camera in position with respect to the dovetail base1561.

Conversely, moving the lever1509in a counterclockwise direction serves to move dovetail side1501away and downward from dovetail platform1503, effectively allowing the camera and platform1503to be simply lifted off the base1561. The mechanism by which this occurs is illustrated in greater detail inFIG. 16.FIG. 16shows a schematic partial cross sectional view of a plane defined by axes7and13ofFIG. 1.FIG. 16ashows the mechanism in a compressed position, i.e., clamped with dovetail side1601pressed against a mating surface of dovetail platform1603. In this view, it can be seen that dovetail side1601is pivotally linked to side piece1635corresponding to side piece1535at pivot1619. Corresponding side piece1633is hidden from view behind side piece1635, but acts identically to side piece1635.

According to one feature of the invention, the dovetail side1601physically moves outward and downward to allow the dovetail platform1603to be easily placed and located beneath the stationary dovetail side along the opposite edge of the dovetail platform1603. In this way, as lever1509ofFIG. 15is moved from its compressed position in a counterclockwise direction, the reverse process to that described above occurs; that is, side piece1635pushes dovetail side1601away from platform1603. The dovetail side1601is then physically moved downward, through the horizontal plane by a camming arrangement. In the presently preferred camming arrangement, this movement is the result of the engagement of a trip lever1611and a trip catch1613, although other camming arrangements are likewise within the spirit and scope of the invention.

As can be seen inFIG. 16b, as dovetail side1601moves away, trip lever1611, which is pivotally mounted to dovetail side1601at1617, slides to engagement with the downward projection of trip catch1613. Both the trip lever1611and the dovetail1601are biased upward. Trip catch1613is fixed to base1561as shown and does not move with dovetail side1601. Consequently, as side piece1635continues to push dovetail side1601away from platform1603, trip lever1611, which can no longer move linearly because it abuts catch1613, rotates counterclockwise, exerting a clockwise rotational force on dovetail side1601, forcing it downward, as seen inFIG. 16c.

The clockwise rotational force depends upon the pivot point1617of the trip lever1611being lower than the pivot point1619between side piece1635and dovetail side1601. Theoretically, the force exerted along link lever1611can be resolved into two perpendicular components. One component1621is directed along the line between pivot points1619and1617, and this component has no effect and produces no movement. The other component1623is perpendicular to the line between pivot points1619and1617, and it is this component that produces the clockwise rotation that moves the side piece1601downward from platform1603.

While the trip lever1611has been shown pivotably coupled to the side piece1601and the trip catch1613fixed to the base1561, it will be appreciated by those of skill in the art that the trip lever could alternately be pivotably coupled to the base and the trip catch fixed to the side piece. Under such an arrangement, the trip lever could slide along the upper surface of the side piece until it engages the trip catch at which time continued force exertion would cause the side piece to pivot the dovetail side down and through the horizontal plane. In such an arrangement, the pivot axis of the trip lever would be disposed above, rather than below, the pivot axis of the side piece. These are but two examples of how such a camming arrangement may be incorporated to provide the lowering movement of the dovetail side. It is further within the invention, as will be appreciated by those of skill in the art, to actuate the dovetail side1601such that substantial lateral movement is not required before downward movement of the side1601commences.

Returning toFIG. 15, once the dovetail platform1503is placed on the base, but before it is locked into position by the force of dovetail side1501, it is desirable to adjust the position of the camera fore and aft to properly place the camera center of gravity. In the platform according to an embodiment of the invention, a pinion gear1547is used to move rack1549thus moving the dovetail platform1503and attached camera. This movement may be provided by way of a rotatable knob1559, which is coupled to the pinion gear1547. More specifically, pinion1547is secured to shaft1551. A helical gear1553is also attached to the shaft1551and is also mated to a helical gear1555. In turn, the helical gear1555is attached to a shaft1557that the user may turn by turning attached knob1559. In this manner, the user may conveniently use knob1559to move the dovetail platform1503fore and aft to properly place the camera center of gravity once the platform1503is resting on but not locked to the base.

It will be appreciated that a new and novel camera panhead, rollhead, mounting system, and power system have been described herein. In view of the many possible embodiments to which the principles of this invention may be applied, it should be recognized that the embodiments described herein with respect to the drawing figures are meant to be illustrative only and should not be taken as limiting the scope of invention. For example, those of skill in the art will recognize that the illustrated embodiments can be modified in arrangement and detail without departing from the spirit of the invention. Therefore, the invention as described herein contemplates all such embodiments as may come within the scope of the claims and equivalents thereof.