Liquid purification or separation – Filter – With central pervious tubular receiver
Reexamination Certificate
2000-07-10
2001-08-28
Upton, Christopher (Department: 1724)
Liquid purification or separation
Filter
With central pervious tubular receiver
C210S488000, C210S497010, C210S499000
Reexamination Certificate
active
06279751
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
REFERENCE TO A “MICROFICHE APPENDIX”
Not Applicable.
FIELD OF THE INVENTION
The present invention relates to filters for liquids. In particular, the present invention is a filtration device for removing particulate matter, debris and other items found as contaminants in solutions used in photographic processing equipment.
BACKGROUND OF THE INVENTION
In recent years, businesses offering rapid processing and printing of color print film, the “One Hour Photo” services, have proliferated. The commercial availability of the automated machines used for this rapid processing and printing, and their comparatively low cost have enabled many small business owners to enter the field, so that the photofinishing business is no longer confined to a few major commercial photo laboratories.
The processing equipment uses a variety of chemicals for film processing and printing. Each chemical is kept in a separate tank or reservoir from which it is pumped into the processing area of the machine at an appropriate time. After the specified time period for the chemical to be in contact with the film or print being processed, the chemical is pumped back to its storage tank, for reuse. The manufacturers supply directions as to the working life of each agent, and directions as how to replenish the chemicals after a specified usage. In the course of processing and storage of the chemicals, various types of particulate matter, debris such as film fragments or paper fragments, aggregates of photographic chemicals, dirt, dust, or microorganisms such as algae or bacteria may contaminate the chemicals and their storage tanks. The presence of contaminants can damage film or prints being processed by scratching negatives or prints, causing losses that may require reprocessing or retouching, assuming such damage can be remedied. Contaminants may decrease the efficacy of the chemicals themselves, or clog up the processing equipment, resulting in lost time spent to clean the equipment.
Although disposable filters are available, their replacement cost over time can be significant. The cumulative disposal of filters also has an environmental impact.
Nondisposable filters utilized in this equipment are difficult to reuse because the filtration material is mounted on the inside of the filter. Consequently, these filters are difficult to clean thoroughly. Some of the materials used to manufacture these filters are subject to being washed off or damaged when subjected to cleaning, thus preventing their reuse.
One commercially available product employs a stainless steel filter tube that is fitted over a frame manufactured from an extruded plastic material. Although this filter fits on the frame like a sleeve, it is difficult to clean and maneuver into a good (i.e., fluid-tight) fit within the apparatus.
Thus there is a need for a filtration device having a filter that in made of a reusable filtration material that is reusable, that won't be washed off of its support matrix during cleaning, and that won't be damaged during cleaning. Further, the filtration device should be made of materials capable of withstanding the physical conditions, including pressures, temperatures and flow rates, and chemical conditions of the environment of photographic processing chemicals in automated processing machines.
BRIEF SUMMARY OF THE INVENTION
An object of the present invention is to provide a filtration device that comprises a filter made of a reusable material.
Another object of the present invention is to provide a filtration device that can be used repeatedly over a long time period, making it economical to use.
Still another object of the present invention is to provide a filtration device that can withstand the extremes of pH that are characteristic of photographic developing and processing chemicals.
Yet another object of the present invention is to provide a filtration device which can be easily removed from its housing, washed free of particulate matter and other debris accumulated on the filter surface, and then be reused.
Still another object of the present invention is to provide a filtration device comprising a filtration material that is not readily damaged when being washed.
Yet another object of the present invention is to provide a filtration device in which the flow of the fluid is from the outside of the filter through the filter body and out through the inside of the filter body.
Still another object of the present invention is to provide a filtration device that can be used in a variety of high speed photographic processing equipment.
Yet another object of the present invention is to provide a filtration device that can be used in a variety of low speed photographic processing equipment.
The present invention is a filtration device for removing particulate matter from liquids, the filtration device having a rigid tubular body that terminates in a pair of open ends. The body has a plurality of openings therein, and a layer of a filtration material, such as a polypropylene mesh, is stretched over the surface of the body. The body is manufactured from plastic, and has a support means which prevents collapse of the filtration device under pressure. The filtration material is glued in place near the ends of the body, and a pair of end caps are attached to the ends. The end caps serve as means of fitting the filtration device within equipment such as automated photographic processing apparatus. The materials used to manufacture the filtration device are chosen so as to be resistant to both the physical conditions (such as temperature, pressure and flow rate) and the chemical conditions of the apparatus (such as developing agents, fixers or bleach solutions). An advantage of having the filter material on the outside is that liquid flows from outside the filter, through the body and the inside, trapping particulate matter on the outside surface of the filter. The filter can be removed from the equipment where it is used, and particulate matter trapped on its surface washed off, and the filter can be reused, resulting in a substantial cost savings compared to the use of disposable filters.
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Two photographs of a prior filter device.
Burns Doane Swecker & Mathis L.L.P.
Upton Christopher
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