Camera track and dolly system

Abstract

A system for moving a camera along a predefined path in space, the system comprising: a track (2), the track comprising at least one rail (10, 12); a dolly (4) adapted to ride on the track; and a rack and pinion drive mechanism (6) for driving the dolly along the track. The drive mechanism includes a rack (40) extending along the track and a driven pinion (60) mounted on the dolly, and the rack is positioned vertically inline with the at least one rail of the track.

Description

FIELD OF THE INVENTION[0001]The present invention relates to camera track and dolly systems for moving cameras (e.g. film and / or video cameras) along a predetermined path.BACKGROUND[0002]When creating films and videos it is very often necessary to change the orientation and position in space of one or more cameras during shooting. To control the orientation of a film or video camera it is known to mount the camera on a remote control head, enabling pan, tilt and roll movements of the camera and lens. Movement of the camera in space is typically achieved by mounting the camera (generally on its remote control head) on a carriage, known as a “dolly”, that rides on a linear track.[0003]Known track and dolly systems typically use tracks having a pair of parallel rails. The rails are held a fixed, constant distance apart by sleepers spaced along the track at regular intervals. Some systems use only straight tracks but other use curved tracks or combinations of straight and curved tracks ...

AI Technical Summary

Benefits of technology

[0015]By mounting the rack inline with a rail of a (single or twin rail) curved track the pitch circle diameter of the rack is the same as the pitch circle diameter of the rail with respect to the pinion of the rack and pinion drive mechanism and remains so as the dolly (on which the pinion is mounted) rides along the curved track. In this way it is much easier to ensure that the PCD of the pinion relative to the rack is maintained along the length of the track even at transitions from straight to curved sections of the track and vice versa.

[0022]Preferred embodiments of the present invention use a flexible rack component, e.g. of a moulded rubber or plastics material, that can readily conform to the shape of a curved track. This allows the rack to be flexed to assemble it with a curved support member section (for a correspondingly curved rail), for example by introducing it at one end of the support member section and sliding it into or onto locating and retaining formations on the support from that end.

[0023]The pinion of the rack and pinion drive mechanism is mounted on the dolly such that when the dolly sits on the rail or rails of the track the pinion (typically a spur gear) engages the rack. By driving the pinion the dolly can therefore be moved back and forth along the track and the positive engagement of the pinion with the rack results in very accurate and repeatable positioning of the dolly (and hence the camera that it carries) along the length of the track.

[0024]Furthermore, with the rack component of the rack and pinion drive mechanism mounted in the preferred manner discussed above, the rack is by default retained inline with the rail along the complete length of the track, enabling the relative position of the rack and pinion to be easily maintained irrespective of the curvature of the track.

[0025]To further ensure that the pinion (more specifically the PCD of the pinion) can maintain its optimum position with respect to the rack, the pinion is preferably mounted on the dolly in a manner that allows its rotational axis to itself pivot about a vertical axis in line with the vertical center line of the rail with which the rack is associated. For example, the drive shaft of the pinion (which is at its rotational axis) can be mounted on a swinging arm that pivots on a bearing mounted on the dolly to be inline with the vertical center line of the rail as the dolly rides along the track. This enables some degree of movement of the pinion relative to the dolly to ensure that it remains properly engaged with the rack at all times, especially at transitions between straight and curved sections of the track.

Problems solved by technology

On curved tracks, however, friction drives have been found to slip, resulting in less accurate repetition of camera movements.

A winch drive can give better accuracy for repeating movements on curved tracks but, as noted above, this approach significantly restricts the extent to which the track can curve.

Rack and pinion arrangements are, however, not easy to use with curved tracks as it is necessary to ensure that the correct pitch circle diameter (“PCD”) of the pinion relative to the rack is maintained along the length of the track and it can be particularly difficult to do this at transitions between straight and curved sections of track.

Curved racks are also expensive.

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