Winding – tensioning – or guiding – Material guide or guard – With material confining portion
Reexamination Certificate
1999-11-08
2001-04-24
Mansen, Michael R. (Department: 3653)
Winding, tensioning, or guiding
Material guide or guard
With material confining portion
C492S008000, C226S190000
Reexamination Certificate
active
06220542
ABSTRACT:
FIELD OF THE INVENTION
The instant invention relates to rollers for use in polymeric film handling systems, more particularly to film transport rollers which are modified to prevent sticking and bunching of the film due to build-up of static electric charges.
BACKGROUND OF THE INVENTION
Motion picture equipment currently used in theaters utilizes complex film handling systems which require the film to travel considerable distances from the supply reel to the projector and back to the take-up reel. The film also passes over a number of guiding or film transport rollers and through feed controls also utilizing such rollers. A considerable amount of static electricity often builds up on the the film, especially during dry conditions, causing the film to stick and/or bunch. This requires the projectionist to stop and rethread the film, often causing unrest among the theater patrons. Various means have been devised to remove the static electricity and thereby to eliminate this problem.
U.S. Pat. No. 3,585,446 to McKee disclosed a conducting system to dissipate static electric charges that build up on motion picture reels. A plastic spindle covered with a conductive coating was secured to the metal shaft supporting the reel. The coating was in contact with both metal flanges of the reel and with the shaft, enabling the charges to migrate from the reel to the coating and then to the shaft and finally to the projector where the charges were dissipated. The projector preferably was grounded.
Whitmore, in U.S. Pat. No. 3,611,028 disclosed a metal roller with metal stub axles which were supported by the grounded frame of a conveyor system. The metal roller, used to guide a web, particularly photographic film, was covered with a layer of an elastomeric plastic which prevented charges on the metal roller from being imparted to the film.
Rollers, composed of non-magnetic stainless steel, in contact with brushes for grounding, were used in a complex web device color copier photoelectrophoretic imaging machine as taught by Hermanson in U.S. Pat. No. 4,049,343. A conductive web surface, in contact with a roller, was grounded by another set of brushes.
Geyken, in U.S. Pat. No. 4,392,177 described four embodiments of rollers for use with webs, sheets or strips of flexible radiation sensitive material such as X-ray film. The rollers were constructed of a plastic material with imbedded metal particles surrounding a metal shaft that extended beyond the ends of the plastic material. The metal shaft was grounded.
In U.S. Pat. No. 4,737,809, Konno taught a camera fitted with two guide rollers in pressure contact with the film. Both guide rollers were in further contact with springs that contacted grounding parts of the camera to remove static charges generated on the film under dry conditions.
Another roller for use with lengths of polymeric film was taught by Ko in U.S. Pat. No. 5,216,571. A metallic conducting core having a metal shaft at each end was surrounded by a non-conducting material having a helical groove cut into it. A conducting wire placed in the groove was in contact with a grounded bearing located at the end of one shaft. The wire had conducting needles radiating outwardly along its length.
Means to remove static electricity from photographic film was taught by Oosaka in U.S. Pat. No. 5,625,468. Four embodiments were described: a metal brush that contacted the perforated edge of the film; arms in contact with conducting members that made contact with each side of the film; conductive pins that contacted the edge of the film; and conductive flanges that contacted the edge of the film. All of these contact means were conductors and all were grounded.
All of the prior art devices for the prevention of sticking or bunching of flexible films or webs depended on the removal of the static electricity from the films or webs through one or another form of ground. There is a need for a simple means to prevent such sticking or bunching of films that can be used with a variety of film handling methods and apparatuses without the additional requirement of a ground.
BRIEF SUMMARY OF THE INVENTION
The present invention may be a guide or film transport roller for use with professional film handling and projection systems. In such systems the film may be introduced into the system by way of a film control plate and threaded over several film transport rollers as it passes to the projector after which it may return again by passing over a number of film transport rollers to a film receiving plate. The polymeric films used today may tend to develope a considerable charge of static electricity when utilized in such systems, especially under conditions of low atmospheric humidity. Such charges may cause the film to stick or bunch which in turn may necessitate that the projectionist stop the film and rethread it through the system. A modified film transport roller may be provided for use with polymeric flexible webs such as motion picture film which may prevent the film from sticking or bunching by polarizing static electric charges that may build up on the film as it moves through the film handling system.
It is an object of the present invention to provide a film transport roller that can be used with conventional film handling systems without the need to modify or change the systems.
Another object of the present invention is to provide a simple modification to film transport rollers such that they will polarize any static electric charges that may build up on the film.
A further object of the present invention is to provide a film transport roller that is easy and inexpensive to manufacture.
A still further object of the present invention is to provide a film transport roller that does not have to be grounded so that special considerations are not necessary in the placement of such rollers in a large or complex apparatus.
Another object of the present invention is to provide a film transport roller that can be interchanged with rollers already in use.
A film transport roller for use in polarizing static electric charges present on polymeric films with which it is in moving relationship comprising a non-conducting core having a cylindrical outer surface covered with a magnetized coating.
A method for preventing the bunching and sticking of a linear web that is passed through a web handling system requiring said web to travel a distance over a multiplicity of web transport rollers from a feed control member to a receiving member over which distance the web acquires a build-up of static electric charges, said method comprising the steps of providing a modified web transport roller having a cylindrical core, guide flanges disposed at each end of said core and a coating of magnetic polymeric material having an associated magnetic field surrounding the core and forming a web contacting surface of said roller; removing at least one web transport roller from the web handling system; replacing the web transport roller that has been removed with the modified web transport roller; threading the web through the web handling system; and running the web through the web handling system; whereby as the web passes over the modified web transport roller and through the magnetic field the static electric charges are polarized preventing the web from bunching and sticking.
A method for preventing the bunching and sticking of motion picture film that is passed through a film handling system requiring the film to travel a distance over a multiplicity of film transport rollers from a feed control plate to a projector and return to a film receiving plate over which distance the film acquires a build-up of static electric charges, said method comprising the steps of providing a modified film transport roller having a cylindrical core, collar means disposed at both ends of said core forming a film contacting surface of the roller, guide flanges disposed at each end of said core contiguous with said collar means and a coating of flexible magnetic polymeric material having an associated magnetic field surrounding the core and of
Kotin Sandra M.
Mansen Michael R.
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