Abstract:
The track system of the present invention provides dolly track whose joints are substantially seamless, providing a substantially smooth riding surface over the entire length of joined sections of track. The ferrule design of the invention provides ridged piece to piece joining, eliminating pinching and hinging points. This allows multiple assembled track pieces to be moved without damage. The system uses self locking track buckles. A folding cross member system may be folded for ease of movement and placement. In one embodiment, the track is comprised of a carbon fiber hybrid composite with lighter weight and greater strength than prior art steel or aluminum tracks. In addition the track of the present invention does not bend, eliminating the need to reshape or repair the track each time before use.

Description:
RELATED APPLICATION 
   This patent application claims priority to provisional patent application 60/671,245 filed on Apr. 12, 2005 and incorporated by reference herein in its entirety. 

   BACKGROUND OF THE INVENTION 
   Motion pictures often use cameras mounted on a wheeled dolly for certain shots. The wheeled dolly travels on a track, similar to a train track in that it comprises two rails mounted on cross members. 
   Dolly track is often rented instead of owned. Not all shots require a dolly mounted camera so it is often useful to rent dollies and dolly track only for scenes or shoots that require it. Because of this, rental track is often mishandled and damaged by renters. Even when owned, dolly track may become worn and damaged by use. This is a problem because an important aspect of the dolly track is to provide a smooth surface for moving the camera during the shot. Imperfections in the dolly track can result in unwanted vibrations in the camera, degrading the camera shot. Because dolly track is comprised of joined sections of track, there are joints between sections that have the potential for creating breaks or bumps in the track surface that can be transmitted to the camera during use. In addition, the dolly wheels traveling over these joints can make unwanted noise that is transmitted to the scene being recorded. 
   One prior art solution to dolly track problems is to use tube style tracks to provide a smooth surface for the dolly wheels. Even with a tube track, the joints are susceptible to poor joins, leading to unwanted surface variations. One prior art track solution is described in U.S. Pat. No. 6,435,421. 
   There are a number of disadvantages of prior art track systems. One disadvantage is that it is not possible to carry joined sections of track without damaging the track and increasing the possibilities of poor joint performance. This requires completely disassembling all track pieces when the track is to be moved. This is a time consuming process and adds to the cost of filmmaking. Another disadvantage of prior art track systems is the changing performance when temperatures change. The tracks lack consistent performance over typically temperature ranges of use. Another disadvantage of prior art tube tracks is the method used for joining the track sections. The methods used often result in a poor joint that interrupts the desired smooth surface of track. Another disadvantage is that metal tracks can bend or be dented. When a track section is bent, it must be leveled before it can be used. Often a great deal of time is spend before operation simply in leveling or straightening track sections. 
   SUMMARY OF THE INVENTION 
   The track system of the present invention provides dolly track whose joints are substantially seamless, providing a substantially smooth riding surface over the entire length of joined sections of track. The ferrule design of the invention provides ridged piece to piece joining, eliminating pinching and hinging points. This allows multiple assembled track pieces to be moved without damage. The system uses self locking track buckles. A folding cross member system may be folded for ease of movement and placement. In one embodiment, the track is comprised of a carbon fiber hybrid composite with lighter weight and greater strength than prior art steel or aluminum tracks. In addition the track of the present invention does not bend, eliminating the need to reshape or repair the track each time before use. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features, aspects and advantages of the invention will become better understood with regard to the following description, appended claims and accompanying drawings where: 
       FIG. 1  is a cross sectional end view of an embodiment of the track of the invention. 
       FIG. 2  is an isometric view of the track of  FIG. 1  unfolded. 
       FIGS. 3A-3D  illustrate an embodiment of a cross member of the invention. 
       FIG. 4  is a top view of a folded track section. 
       FIGS. 5A-5C  illustrate one embodiment of the ferrules of the invention. 
       FIG. 6  illustrates the track joining mechanism of the invention. 
       FIGS. 7A-7E  illustrate another embodiment of a buckle system for use with the invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   In the following description of the invention, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration a specific embodiment in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope and spirit of the invention. 
   The invention provides a light and strong dolly track comprised of a carbon fiber/hybrid composite. The material has a certain memory so that even if it is overloaded it does not bend and returns to its true shape each time. It has a very low thermal reactivity so that the track has consistent performance over operating temperatures. The ferrule design of the invention provides a ridged section connection that eliminates pinch/hinging points. This permits assembled track sections to be carried without damaging the track. 
     FIG. 1  illustrates an end view of an embodiment of the invention in a folded position. The track consists of a pair of rail tubes  101  and  102 . The tubes rest on support members  103  and  104  respectively. Each support member has a curved section  105  and  106  that receives and holds the tubes  101  and  102 . In one embodiment the tubes are bonded to the support members with adhesives. In another embodiment, the tubes are coupled to the support members using mechanical fastening means, such as rivets  121  and  122  illustrated in  FIG. 1 . 
   The outside portion of the support members have a substantially rectangular section  107  and  108  that extends to the floor for track support. Upper inner portions  109  and  110  each have a hub  111  and  112  for pivotally mounting the cross members  117  and  118 . Sleeves  113  and  114  are pivotally mounted through cross sections  117  and  118  to hubs  115  and  116 . When the track rails are moved apart, the pivotally mounted cross sections can rotate from a closed and substantially co-linear position with the tubes to a substantially perpendicular position for track use. As can be seen in  FIG. 1 , in this embodiment, the rails are slightly separated when the track is in the folded position. The regions  109  and  110  of support members  103  and  104  come together to form a closed portion to protect the cross members from dust or other contaminants when the track section is folded. Sections  123  and  124  form part of the bottom support surface for the track sections. In one embodiment, the bottom surface of the support members are coated with a non-skid coating or material to help hold the track sections in place during use. 
     FIG. 2  illustrates an isometric view of one embodiment of a track section unfolded for use. Tube rails  201  and  202  are separated and positioned by cross members  205 A- 205 E. Referring to cross member  205 A, it can be seen that it is pivotally mounted to rail  201  at pivot mounting point  203 . Similarly, cross member  205 A is pivotally coupled to rail  202  at pivot mounting point  204 . The cross members can pivot in either direction for ease of use, movement and positioning. As seen in  FIG. 2 , the inner and upper portion  109  of the support member is recessed from the end of the track and the rest of the support member. In one embodiment, this recess is there so that buckles for joining track sections can be located there. 
     FIGS. 3A-3D  illustrate a cross member of an embodiment of the invention. The cross member  301  includes two sides, each having straight and curved sections. For example the left end of cross member  301  has an upper straight portion and a lower curved portion  304 . Conversely the right end of cross member  301  has an upper curved portion  305  and lower straight portion  303 . The cross member  302  includes openings  306  and  307  formed therein to permit the pivotal mounting of the cross member to the support members of the rails. In operation, the curved portions  304  and  305  of the cross member  301  permit the rotation of the cross member relative to the rails in one direction for closing. When opening, the straight portions  302  and  303  of the cross member serve as an automatic limit on the rotation of the cross member with respect to the rails, locking the cross member in its desired open position automatically. 
     FIG. 4  illustrates a view of a folded track section. When folded, one rail is offset from the other due to the pivoting action of the cross members. Rail  401  sticks out at one end while rail  402  sticks out at the other end. In  FIG. 4 , cross member  403  is visible in a folded position at one end of the folded track section. 
     FIGS. 5A-5C  illustrate one embodiment of the ferrules used in the invention for joining track sections. Tube rails  501  and  502  are shown from a track section. Rail  501  includes a male ferrule  506  mounted on its end. The male ferrule  506  comprises a cap  503 , plug  507  and shaft  504 . The cap  503  includes a rim on its edge that has an outer diameter coincident with the outer diameter of the rail  501 . The plug  507  is sized such that it can be mounted within the diameter of the rail tube  501 . In one embodiment the ferrule  506  is coupled to the shaft by bonding it to the shaft, such as by using adhesives. In one embodiment, the male ferrule shaft  504  is tapered for ease of insertion into the female ferrule  508 , shown mounted within rail  502 . The female ferrule comprises an inverted tapered cone shape for receiving the tapered shaft  504  of the male ferrule  506 . 
   In operation the shaft  504  of the male ferrule  506  would be inserted into the opening (e.g. opening  505 ) and ultimately into the tapered opening of female ferrule  508  of rail  502 . As can be seen, by having the female ferrule  508  including a tapered opening, the shaft  504  of male ferrule  506  can have full contact with the female ferrule  508 , improving strength after joining. After insertion, buckles or some sort of latching members on the cross sections of the track would be locked in place to provide a compression fit of the two track sections. By using the ferrule  506 , the joint between the tracks is substantially continuous, with no gaps or raised areas. This is because the track tube is joined face to face with its corresponding partner. When the dolly wheels roll over the joint, it is substantially seamless so that substantially no vibration or sound introduced into the dolly by the joint, providing a smooth travel surface along all joined sections. 
   The shaft  504  of the ferrule  506  is sized so as to provide a relatively tight fit with in the opening  505  of a rail tube. This provides strength to the joint during use and also the ability to carry joined sections of track without weakness at the joints leading to bends and dents. 
     FIG. 6  illustrates one embodiment of a method of joining and locking track sections in the invention. This figure illustrates two track sections  601  and  602 . Track section  601  includes rails  603  and  605 , cross member  611 , buckle  609 , latch  615 , pin  617 , and ferrule  607 . Track section  602  includes rails  604  and  606 , cross member  612 , buckle  616 , latch  618 , pin  614 , and ferrule  608 . In this embodiment, the ends of any pair of tracks include one ferrule and one opening for receiving a ferrule. Here, the shaft of ferrule  607  of track section  601  is inserted into the opening of rail  604 , joining rails  603  and  604 . Correspondingly, the shaft of ferrule  608  of track section  602  is inserted into the opening of rail  605 , joining rails  605  and  606 . 
   To secure the rail sections together and to minimize any gaps at the joints, the invention provides cross members relatively near the ends of the rails and latching mechanisms to lock the two sections together. In the embodiment of  FIG. 6 , cross member  611  includes a buckle  609  that has a latch  615  that engages a pin  614  on cross member  612 . The buckle is then closed, tensioning the latch  615  and pulling the two track sections  601  and  602  towards each other for a secure and tight fit. Similarly, buckle  616  of cross member  612  includes a latch  618  that engages pin  617  of cross member  611 . When the buckle is closed, the latch is tensioned and pulls track sections  601  and  602  together in a secure fit. 
     FIGS. 7A-7E  illustrate another embodiment of joining track sections together.  FIG. 7A  shows a clevis mounted to an inside surface of an interior of support member  703 .  FIGS. 7B and 7C  are different views showing parts of the buckle.  FIG. 7D  shows a lever rotatably mounted on the clevis, and a latch rotatably mounted on the lever.  FIG. 7E  shows the latch captured by a fastener. In this embodiment, the buckle  701  is mounted sideways on the support member  703  of rail  702 . As noted in  FIG. 1 , there is an open section at the terminal end of the inner portion of the support member for receiving the buckle  701 . A post or pin on the opposite track section receives a latch from buckle  701 . A cam lever action is then closed to tighten the buckle and pull the two track sections together as noted above. In one embodiment, the end of each section includes a buckle on one side and a latch post or pin on the other side. 
   In one embodiment of the invention, the tube is comprised of a hybrid composite of fiberglass and carbon fiber. The material may be worked by pull-trusion or any other suitable means of forming hollow tubes. After initial forming, the ferrules can be placed in the tube such as by adhesive or any other suitable coupling means. The entire tube and ferrule assembly can then be further machined together to the tolerances desired. By doing this processing step in this manner, the problems of machining or producing separate pieces to exact tolerances is minimized and avoided.