Photography – Fluid-treating apparatus – Fluid application to one side only of photographic medium
Patent
1995-10-23
1997-07-15
Rutledge, D.
Photography
Fluid-treating apparatus
Fluid application to one side only of photographic medium
G03D 500
Patent
active
056492626
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a film cleaning apparatus and method and more specifically but not exclusively to such an apparatus and method for removal of dust from cinematographic films.
BACKGROUND OF THE INVENTION
The presence of dust and dirt on cinematographic films is a considerable problem in that it impairs the projected image and can lead to scratching of the film during transport through a projector. Various methods have been considered for removal of dust and dirt from films and perhaps the simplest idea would be to attempt to simply blow particles from the film. However, this is not satisfactory as electrostatic attraction of particles to cinematographic films makes it difficult to shift such particles. If a continuous jet of air is directed at the surface of a film an air boundary layer very close to the film surface is formed and this creates a downward pressure causing particles to cling to the film surface. The smaller the particles, the greater is the hold on the surface. The higher the velocity of air used the more pressure is exerted in or by the boundary layer making small particles apparently immovable. Accordingly such an arrangement will not work satisfactorily and will not remove grease.
In current cinematographic Film Cleaners. Film is cleaned by ultrasonic vibration of the film as it is passed through a bath containing a volatile hot liquid. The ultrasonics are generated electronically, and physically coupled from a transducer via the liquid in the bath, causing vibration of the Film which removes dust, dirt and grease by surface cavitation. the Film is then passed through a drying tower which evaporates the liquid and dries the Film. However, this drying process limits the cleaning speed of the film to approximately 200 feet per minute with current solvents and is expensive due to the solvent costs. Furthermore, the solvent most commonly used in the film cleaning process is Trichloreoethane--a CFC--which is being phased out from January 1994.
The present invention seeks to provide an alternative film cleaning apparatus and method which provides significant advantages over existing film cleaners.
SUMMARY OF THE INVENTION
According to the invention there is provided a film cleaning apparatus comprising a container provided with means for exposing the surface of the film to mercury which effects removal of contamination therefrom.
The mercury may be provided as a bath through which the film is transported and/or in the form of pressure jets.
Where a bath is employed the apparatus may include a transducer for introducing vibration into the mercury in the bath for example an ultrasonic transducer.
According to another aspect of the invention there is provided a method of cleaning a film comprising the steps of feeding the film through a cleaning station exposing the film to a supply of mercury to remove contaminants therefrom and purging the film of mercury.
BRIEF DESCRIPTION OF THE DRAWINGS
In order that the invention and its various other preferred features may be understood more easily, some embodiments thereof will now be described, by way of example only, with reference to the drawings which are schematic only and in which:
FIG. 1 is an illustration of the effect of a continuous flow of gas over a flat surface,
FIG. 2 shows part of a basic film cleaning apparatus employing the principles of the invention in which the film is routed through a mercury bath,
FIG. 3 shows part of an alternative film cleaning apparatus employing the principles of the invention in which the film is subjected to mercury pressure jets,
FIG. 4 shows part of another alternative film cleaning apparatus employing the principles of the invention where the film is subjected to a combination of mercury bath and pressure jet cleaning,
FIG. 5 shows a front schematic view of a particularly advantageous apparatus constructed in accordance with the invention employing mercury pressure jets mounted on rotatable hubs,
FIG. 6 shows an end schematic view of the apparatus illustrated in FIG.
Walker Michael Albert Chapman
Watts Terence Andrew
Rutledge D.
Walker Michael Albert Chapman
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