Patent Application
20110097074
This invention is in the field of high speed motion picture film processors.
Generally, the processing, sometimes also referred to as developing, of motion picture films consists of passing an exposed film though numerous different chemical solutions.
Modern film processors, sometimes referred to as film developers, consist of a set of tanks, sprockets, and rollers.
The design speed of these processors has been increased over the years. In 1975 the fastest processors were processing film at 300 feet per minute. In 2005 some processors are running at 1000 feet per minute. The problem with processing at high speeds is that the film tension or drag increases drastically as the speed increases. At processing speeds above 1000 feet per minute the film tension becomes excessive due to solution drag. An additional problem which occurs at high speed is the whirling, or bending, of the sprocket shaft 3 which causes severe vibrations in the processor.
As a result of the tension increase at higher speeds, manufacturers began lowering the solution levels such that only a lower portion of the film was submersed in the solution as shown in
The problem with the primary solution is that the developer will oxidize when exposed to excessive amounts oxygen. Since air contains oxygen, oxidation of the developer solution can be eliminated by replacing the air with a gas which will not oxidize the developer.
One section of this patent deals with the design and method of maintaining a low oxygen concentration in the tank. A second section of this patent deals with eliminating the vibrations in the processor when it is running a high speeds
Filling the developer tank 2 with a non-oxidizing gas has been tried several times and found to be unsuccessful. The reason for the failure was not the principle of the approach but rather the execution. In previous attempts to do this the developer tank 2 was not properly sealed, the oxygen concentration was not monitored, the tank 2 pressure was not monitored and the film entry and exit ports were not properly sealed. Sealing the developer tank is not a trivial problem. The wet transport beams 6 may be in excess of 20 feet long and need to be raised (for maintenance purposes) by a distance of up to 10 feet above the tank 2 and again lowered to the top of the tank 2.
The present invention is generally directed to a high speed motion picture film processor having a film feeder, a developer tank having a positive pressure relative to an ambient air pressure outside of the tank, multiple secondary tanks and a film takeup unit wherein film is fed by the film feeder into the developer tank and then into the plurality of secondary tanks before it enters the film takeup unit.
In a separate group of aspects of the present invention, the high speed motion picture film processor also has a gas make-up system for adding a non-reactive gas (such as nitrogen) inside of the developer tank and a system of seals to minimize leakage of the non-reactive gas from inside of the developer tank outside of the developer tank. The system of seals includes a first seal along a periphery of the developer tank below a sprocket level plus a tank cover and a second seal along a second periphery of the tank cover above the sprocket level, the sprocket level being determined by a centerline of a shaft that supports a plurality of sprockets used for high speed processing of film inside of the developer tank.
In another, separate group of aspects of the present invention, the first and the second seals are barriers, such as a knife-edge, with a lower end in a liquid reservoir which is filled with the developer solution by operation of the high speed motion picture film processor when the high speed motion picture film processor is in operation. Both the liquid reservoir and the barrier are constructed so as to allow movement of the barrier within the liquid reservoir without allowing the non-reactive gas to exit the developer tank when the high speed motion picture film processor is in operation. The liquid reservoirs are formed by an outer wall, a trough and an inner wall, and the height of the inner wall is less than the height of the outer wall so that when the liquid reservoir overflows any overflow will flow over the inner wall into the developer tank. A mechanism (such as an overpressure relief valve) may also be used to prevent the tank cover from being lifted up by the positive pressure inside of the developer tank.
In still another, separate group of aspects of the present invention, the secondary tanks may also have a dual sealing system similar to that described for the developer tank, although the secondary tank is maintained at a slight negative pressure relative to the ambient air pressure external the secondary tank.
In yet another, separate group of aspects of the present invention, the developer tank also has a film entrance sealing device and a film exit sealing device, each of which has a housing, a pair of rollers located inside the housing to deflect the path of the film within the housing and a pair of flexible barriers located in the housing. The pair of flexible barriers (which may be a pair of wiper blades or a barrier pair of rollers) are located in the path of the film between the pair of rollers so that the film passes between a gap (which may be approximately a few thousands of an inch or less) between the pair of flexible barriers when the film processor is in operation. The pair of flexible barriers separate a tank gas chamber located in the housing in communication with the developer tank from an air chamber located in another portion of the housing in communication with ambient air and the tank gas chamber contains the non-reactive gas contained in the developer tank at a pressure slightly higher than the pressure in the air chamber. The air chamber of the film entrance sealing device also contains a partial pressure of the non-reactive gas contained in the developer tank and non-reactive gas can be fed into the air chamber to maintain the partial pressure.
In a further, separate group of aspects of the present invention, the developer tank has a sprocket shaft with multiple sprockets and two roller shafts which each have multiple rollers located proximate a bottom of the tank but at different levels relative to one another in the tank while the developer solution is maintained at a fluid level which is approximately located at a centerline of the first roller shaft so that the rollers of the second roller shaft are above the centerline and thus above the developer solution.
In still a further, separate group of aspects of the present invention, the sprocket shaft in the developer tank has a two small shafts mounted on two sets of bearings (which may be metal bearings) inside two beams with two flexible seals for preventing gas from leaving the developer tank on two sides of the developer tank opposite each other and a tube (which may be solid, but is preferably hollow) with a larger diameter than the small shafts is affixed at each of its ends to one of the small shafts, while sprockets are mounted on the tube. Rotational and lateral movement of the sprockets on and relative to the tube can be prevented. One way to prevent rotational movement of the sprockets is to use pins inserted through the tube and held in place by opposing indents formed in the sprockets. The inside of the two beams can be slightly pressurized relative to the positive pressure of the developer tank.
In yet a further, separate group of aspects of the present invention, an oxygen sensor is located outside of the developer tank for sounding an alarm whenever oxygen concentration exceeds a desired set point. A gas line feeds the non-reactive gas inside of the developer tank to a filter and then to the oxygen sensor due to the positive pressure of the non-reactive gas within the developer tank, and the gas may be exhausted through a throttling device. A secondary oxygen sensor, with its own exhaust throttling device, may also be located outside of the developer tank and the flow of gas may periodically be switched between the two oxygen sensor devices.
Accordingly, it is a primary object of the present invention to provide an improved high speed motion picture film processor.
This and further objects and advantages will be apparent to those skilled in the art in connection with the drawings and the detailed description of the preferred embodiment set forth below.
In accordance with the present invention, a high speed motion picture film developer is disclosed that can be represented in a simplified schematic diagram as shown in
The present invention will now be described in connection with several especially preferred embodiments that illustrate various aspects of the inventive concepts described herein. In the Figures and the following more detailed description, numerals indicate various features of the invention, with like numerals referring to like features throughout both the drawings and the description. Although the Figures are described in greater detail below, the following is a glossary of the elements identified in the Figures:
In accordance with an especially preferred embodiment of the present invention shown in
To ensure that no oxygen enters developer tank 101, the nitrogen is under positive pressure relative to the air outside the tank. To maintain the positive pressure and compensate for gas leakage, a small amount of nitrogen is continuously pumped into the tank by a make-up nitrogen system 44. To maintain this pressure, the system has to be sealed. In an especially preferred embodiment of the present invention, gaps 10 between beams 6 and developer tank 101 are sealed by a u-shaped tank seal channel 11 (having an outer wall, a trough and an inner wall) that is welded to the entire periphery of the tank as shown in
Similarly, a tank cover 9 with a similar barrier or knife edge 46 is placed into beam seal channel 12. Beam seal channel 12 is connected to beams 6 and runs around the entire periphery of tank cover 9. Beam seal channel 12 can be constructed with a u-shaped channel that is itself affixed to beams 6 or an outside lip 48 of the u-shaped channel can be formed by using the beam itself as a wall. Filling beam seal channel 12 with a liquid forms upper liquid reservoir 52 that provides a seal for the top of developer tank 101 in the same fashion as lower liquid reservoir 51 provides a seal for the developer tank 101 below sprockets 1.
Small shaft 34 is mounted on bearings 13. Bearings 13 have a flexible seal on both sides of bearing 13 which seals the bearing and thus seals the inside of developer tank 101 from ambient air 36.
Since the entire developer tank 101 is under positive pressure, tank cover 9 must be of sufficient weight or must be mechanically latched to beams 6 so that tank cover 9 is not lifted up by the pressure in developer tank 101.
The seals as described above serve an additional purpose. As film 7 moves through the developer solution, a substantial amount of solution is carried to the top of developer tank 101. The seals and covers as described above form a substantially complete seal, if not a complete seal, which prevents the solution from spilling outside developer tank 101.
As film 7 is transported through developer tank 101, there is a tremendous amount of splashing of solution 14 throughout the tank. Inside lip 18 (i.e., the vertical section of tank seal channels 11) must be lower than the top edge of developer tank 101 to prevent liquid 14 from leaving developer tank 101 by spilling over the outside side of the tank. For the same reason, inside lip 18 of beam seal channel 12 (i.e., the vertical section of beam seal channel 12) must be lower than the top of beams 6 to prevent spilling outside of the tank since the tremendous amount of solution splashing within the tank enclosure will automatically fill seal channels 11 and 12 with developer fluid 14.
An important aspect of this especially preferred embodiment of design of tank seal channel 11 and beam seal channel 12 is that the both channels remain full of solution, due to the solution 14 splashing, at all times and thus sealing the tank 2.
The seals described above may also be employed on secondary tanks 102 having secondary solutions to prevent such solutions from spilling outside secondary tanks 102 and to also prevent undesired fumes from escaping from such tanks. Sealing the undesired fumes and preventing them from escaping into the immediate environment is extremely important. There are very pungent and environmentally damaging fumes in the tanks which do present health hazards. Secondary solution tanks 102 are usually provided with a slight negative pressure relative to the ambient pressure to ensure that any leakage into the secondary tanks will be exhausted to the outside of the processor building.
In addition to all of the seals mentioned above, developer tank 101 needs a sealing device which seals film 7 as it enters and exits developer tank 101.
As liquids are added or removed from developer tank 101 the tank pressure may change. If the tank pressure becomes negative the tank will suck in air and therefore oxygen. Consequently, the nitrogen pressure must be controlled with a pressure regulator and must at all times be positive relative to the pressure external to developer tank 101. This positive pressure assures that there is a positive pressure gradient moving from tank gas chamber 31 to air chamber 30. Also, when high speed film processor 100 is turned off, the gas temperature of gas inside of developer tank 101 will cool (the solution might be at 100° F. when running) and additional nitrogen must then be added to the inside of developer tank 101 to maintain its positive pressure (according to Boyle's Law).
The film seal device for sealing the film as it enters developer tank 102 is shown in
As a result of nitrogen passing from tank gas chamber 31 to air chamber 30 there is a certain tank gas concentration in air chamber 30. This is important for the film entering developer tank 101. A partial tank gas atmosphere in air chamber 30 ensures that the perforations in the film are at least partially purged of oxygen. This causes less oxygen to be drawn into developer tank 101. Also, air chamber 30 can be designed to be very large and the partial pressure of tank gas inside of air chamber 30 can be controlled through addition of tank gas into air chamber 30 to minimize oxygen that might be carried into tank gas chamber 31 by film perforations.
Running processors at high speeds requires that sprocket shaft 3 is quite straight.
In an especially preferred embodiment of the present invention small shafts 34 are not submersed. Submersed shafts can ordinarily only be run on plastic bearings because of corrosion problems encountered in the liquids. When small shafts 34 are mounted on the surface, they can be mounted on metal bearings which have a far longer life than plastic bearings. In order to prevent the developer solutions from migrating into the bearings, the inside of beams 6 are slightly pressurized relative to the inside of developer tank 101. This pressure causes any fluid which might migrate into the bearing to be forced out of the bearing and back into developer tank 101.
In order to ensure that developer tank 101 is always pressurized the tank must be equipped with a pressure gauge and an alarm which will sound if the pressure in the tank falls below a minimum set point.
Additionally, it is especially preferred that developer tank 101 is equipped with a primary oxygen sensor 23 (
Upon starting the processor 100, referring to
While the invention has been described herein with reference to several especially preferred embodiments, these embodiments have been presented by way of example only, and not to limit the scope of the invention. Additional embodiments thereof will be obvious to those skilled in the art having the benefit of this detailed description, especially to meet specific requirements or conditions. For example, while the preferred embodiments have been disclosed as using a liquid reservoir system for seals along the periphery of the developer or secondary tanks, a different suitable seal system could also be put into place, such as an inflatable seal that could replace the liquid reservoir system and still accommodate movement which is common when the high speed motion picture film processor is in operation. Further modifications are also possible in alternative embodiments without departing from the inventive concept.
Accordingly, it will be apparent to those skilled in the art that still further changes and modifications in the actual concepts described herein can readily be made without departing from the spirit and scope of the disclosed inventions as defined by the following claims.
