Abstract:
A camera track system comprising a track ( 100 ), a camera mounted on a movable truck ( 102 ) driven by drive means ( 104 ), control means ( 110 ) for controlling movement of the truck ( 102 ) along the track ( 100 ), in which commands between the control means ( 110 ) and the truck ( 102 ) are effected by means of a flexible link ( 136 ) contained within the track ( 100 ), allowing remote control of the truck ( 102 ). The control means ( 110 ) may comprise separate controls for the camera, operated by the hands of the operator, and for the truck, operated by the feet of the operator.

Description:
The present invention relates to an camera track system and controls therefor. 
     Previously such systems have used tracks to enable the movement of a camera along a fixed path for filming of motion pictures or sporting evens. Such systems have normally involved a camera mounted on a track which is moved by a truck operator whilst the camera is controlled by a cameraman. In previously proposed track camera systems the component to carry cameras and command feeds (wiring) have been placed around an open fabricated truss creating a large component which is often easily visible. Such systems have disadvantages due to their size which limits events which they can film and also due to the two-man operation of the system that it is not possible to take pictures of fast changing events such sporting events. 
     It is a first aim of the present invention to provide a compact track system to overcome size problems. 
     Accordingly, a first aspect of the present invention is directed to a camera track system comprising a camera mounted on a movable truck, track components which releasably join together to form a complete track, drive means which move the camera truck along the track, control means by which the camera and truck are controlled, in which commands between the control means and the camera truck are effected by means of a flexible link contained in the track. 
     Preferably the flexible link is a chain link surrounding power and command cables. 
     Advantageously the flexible link is contained in a boxed structure within the rack which has a slot to allow connection to the camera truck. 
     In a preferred embodiment inside of the boxed structure is provided with friction reducing materials. 
     Preferably the flexible link can be doubled back on itself to enable easy paying in and paying out of it within the boxed structure. 
     This provides the advantage that the track system is considerably more compact with the result that the camera can be mounted considerably close to the ground therefore not interfering with the view of spectators at a sporting event such as a football game. Furthermore, the system is light and portable and can easily be taken apart and put together again. The system due to the link contained in the track enables the system to work equally well in horizontal or vertical planes or when the camera truck is suspended. 
     It is a second aim of the present invention to enable a camera track system to be controlled from a long distance away. 
     Accordingly a second aspect of the present invention is directed to a camera track system comprising a camera mounted on a movable truck, a track, control means for controlling the truck and the camera in which commands are communicated between the control means and the camera track system by means of a RS 422 data link. 
     This provides the advantage that the camera system can be controlled by the operator a considerable distance away in some cases up to 16 kilometers away. 
     It is a third aim of the present invention to enable a camera track system to be controlled by a single person. 
     Accordingly a third aspect of the present invention is directed to a control apparatus for a camera track system, in which a camera is movable mounted on a truck which is movable backwards and forwards along the track, comprising means to control the movement of the camera itself operable by hand and means to control the movement of the truck operable by foot. 
     Preferably the means to control the movement of the truck comprise two pedals, one to move the truck to the left and one to move the truck to the right. 
     Advantageously the amount of depression of each pedal determines the speed of movement of the truck. 
     In a preferred embodiment the means for controlling the camera is a joystick system. 
     Preferably the control system has a number of selectors which upon use move the truck to a predetermined position on the track. 
     This provides the advantage of a moving camera perspective with pictures framed by a single camera person, an ideal perspective when that person is provided a view of for instance, moving play during a football match, where instant reaction to moves can be effected almost as a reaction, rather than by communication to a second operator who in turn would cause the camera truck to move. 
    
    
     An example of a camera system made in accordance with the present invention is described herein below with reference to the accompanying drawings in which: 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a schematic drawing of such a system from above; 
     FIG. 2 shows a side schematic drawing of a system shown in FIG. 1; 
     FIG. 3 shows side and sectional views of track elements; 
     FIG. 4 shows a schematic plan view of the track and control cable; 
     FIG. 5 shows a plan view of the pulley drive for the track system; 
     FIG. 6 shows a side view of the pulley drive of FIG. 4; 
     FIG. 7 shows a top schematic view of the camera truck; 
     FIG. 8 shows a cross sectional view of the camera truck next to the drive unit; 
     FIG. 9 shows views of the camera mounting for the camera for the system; and 
     FIG. 10 is a side view of the control apparatus for such a camera system. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows a schematic drawing of the camera track system. The camera track system is provided with a track  100 . On the track  100  is mounted a movable camera truck  102 . Next to the track  100  in the center is provided a drive unit  104  which contains the servo motors to move the truck  102  backwards and forwards. At either end of the track  100  there are buffers  106  which are made in a known fashion. The truck  102  moves backwards and forwards along the track  100  and is stopped at either end by the buffers  106 . The drive unit  104  is linked by RS 422 data link  108  to a remote control unit  110  which is operated by a single camera person. The track  100 , on either side of the drive unit  104  which has a separate unit of track attached to it, is composed of individual units, units  112  on one side of the drive unit and  114  on the other side. The number of track units  112  and  114  can be varied depending upon the length of coverage required. 
     FIG. 2 shows a side view of the camera track system. The camera truck  102  is moved along the track  100  by an endless toothed belt  116 . The toothed belt  116  runs round two pulleys  118  mounted underneath each buffer  106 . The toothed belt  116  is moved backwards and forwards by a pulley arrangement in a drive unit  104 . The camera truck  102  runs on a track  100  using wheels  120 . The truck  102  is held on the track by lower wheels  122  which restrict its vertical movement. Lateral movement of the truck  102  is restricted by wheels  124  mounted sideways to run on the side of the track  100 . 
     FIG. 3 a  shows a side view and a cross sectional of the track unit  112  and FIG. 3 b  shows a side view and a cross sectional view of the track unit  114 . Both track units  112  and  114  have two rail members  126  on either side of the track unit upon which the wheels  120 ,  122  and  124  of the camera truck  102  run. Between the rail members  126  there is a box structure  128  in both cases. The box structure  128  has a slot  130  in its top surface. Underneath the box structure  128  there is a triangular base compartment  132  at the apex of which are fitted feet  134  upon which the track  100  stands. Inside the box structure  128  in the case of track unit  112  there is a walling around the slot  130  so that half of the box structure  128  is walled off. The track unit  114  however does not have the wall and the whole of the box structure  128  is open inside. The inside of the box structure  128  is designed to hold a control cable  136  for the truck unit  102 . Therefore the exposed inside walls of the box structure  128  are coated with material to reduce friction between the control cable  136  and the inside of the box structure  128 . 
     FIG. 4 shows a schematic drawing of the box structure  128  along the whole length of the track. The area  138  shown in cross hatching corresponds to the boxed in part of the box structure in track units  114 . The camera truck  102  is connected for control purposes to the drive unit  104  by the control cable  136  which runs inside the box structure  128 . The control cable  136  comprises a segmented carrier in which the power and control cables are held. The segmented nature of the control cable  136  allows it to bend and be moved around easily and to be extended or reduced in length as desired. As can be seen from FIG. 4 the control cable  136  is attached at one end to the center unit of the track  100  next to the drive unit  104 . At its other end it is attached to the camera truck  102 . The control cable  136  proceeds to the right of FIG.  4  and then curves round and proceeds back to the camera truck  102 . This means that as the truck  102  moves to either the left or right on FIG. 4 the control cable is either paid out from the loop or doubled back on itself. This means that the control cable  136  can reach either end of the track easily. This is why the track units  112  on the right hand side of FIG. 4 have a open box structure  128  to enable the doubling up of the control cable  136  whereas the track units  114  on the left hand of FIG. 4 only contain a slot as they only have to contain one width of the control cable without the need for it double back on itself. 
     In FIG. 5 shows the drive system used by the drive unit to move the toothed belt  116  comprising two guide pulleys  140  and a drive pulley  142  whereby the toothed belt  116  is fed by the guide pulleys  142  round the outside of the drive pulley  142 . 
     FIG. 6 shows a side view of the drive pulley  142  in the drive unit  104  showing external cable linkages  144  whereby a power and control signals are supplied to the unit  104 . 
     FIG. 7 shows a top schematic view of the truck  102 . Two pairs of wheels  120  can easily be seen running on each rail element  126  of the track  100 . The side wheels  124  are also clearly visible. 
     FIG. 8 shows a side sectional view of the camera truck  102  next to the drive unit  104 . The sets of wheels  120  and  122  above and below the rail element  126  are clearly visible. The connection between the underside of the camera truck  102  and the endless toothed belt  116  which runs underneath the track can be seen clearly. 
     FIG. 9 shows side front and top views of the camera  146  for the camera truck  102 . The camera is mounted in a U-shaped base  148  which is rotationally movable left and right. The camera itself is held in the middle of the U in a unit which is rotationally movable up and down. 
     In FIG. 10 a base  10  is provided upon which a pair of pedals  12  are pivotably mounted by pivots  14 . The base  10  also possesses a mounting point  16  for the fitting of a chair for the operator to sit on. Attached to the pedals  12  are push pull control cables  18 . The push pull control cables  18  are attached underneath the seat at point  20  to linear variable differential transformers  22 . 
     The depression of the left-hand pedal  12  moves the camera truck to the left and depression of the right-hand pedal moves the camera truck to the right. The pedals provide a displacement signal to the servo drive computer of the servo drive motor for the camera truck indicating in which direction the camera truck is to move. The more each pedal is depressed the faster the truck moves. This is accomplished by the push pull cable providing a scale signal produced by the linear variable differential transformer  22 . The linear variable differential transformer  22  provides a precise command which gives a scale signal to the servo drive computer of the servo drive motor for the camera truck. 
     The control position is connected via an RS 422 data link to the camera track system which enables the operation of the camera to be controlled from a distance of up to 16 kilometers.