Patent Application
20070144346
The present invention relates generally to an apparatus and method for thermally processing an imaging media, and more specifically to an apparatus and method for thermally developing an imaging media employing a contaminant removal cartridge to collect airborne contaminants produced by the development process.
Photothermographic film generally includes a base material, such as a thin polymer or paper, typically coated on one side with an emulsion of heat sensitive materials, such as dry silver. Once the film has been subjected to photo-stimulation, such as by light from a laser of a laser imaging system, for example, the resulting latent image is developed through application of heat to the film to form a visible image.
Several types of processing machines have been developed for developing photothermographic film. One type employs a rotating heated drum having multiple pressure rollers positioned around the drum's circumference to hold the film in contact with the drum during development. Another type of processor, commonly referred to as a flat-bed processor, includes multiple rollers spaced to form a generally horizontal transport path that moves the photothermographic film through an oven. Regardless of their type, processors are typically designed to heat the photothermographic film to at least a desired processing temperature for a set time, commonly referred to as the dwell time, for optimal film development.
As the photothermographic film is heated, some types of emulsions produce gasses containing contaminants, such as fatty acids (FAZ), which may subsequently condense when coming in contact with cooler air or surfaces within the processor. When contacting cooler air or cooler surfaces, the gasses may condense and contaminants, fatty acids in particular, may become deposited on the photothermographic film and subsequently be transported to other processor components. These deposits can accumulate over time and can damage processor components, cause film jams within the processor, and cause visual defects in the developed image.
In efforts to reduce the occurrence of such problems, processors generally include systems designed to remove the gasses from the processor before the contaminants can condense. These systems generally include a duct or vent system designed to direct a stream of heated air and gasses from a processing chamber through some type of condensate accumulator and then through a filtering module before exhausting the air to the environment.
Condensate accumulators are generally designed to cool the air stream and cause contaminants to precipitate and collect on accumulator surfaces. Condensate accumulators take a variety of forms, ranging from condensation traps that simply mix ambient air with the heated air stream to various forms of heat exchangers. The cooled air stream is passed from the condensate accumulator through the filtering module. The filtering module typically includes an absorbent block which removes odorous materials before exhausting the air stream from the processor.
While the absorbent block of the filtering module is typically replaceable, the condensate accumulator generally remains affixed to the processor. Also, the condensate accumulator and filter module are typically positioned remotely from the processing chamber and require an extended duct system through which to receive gasses from the processing chamber. Due to its distance from the processing chamber, contaminants often condense and accumulate within the duct system. As a result, even though the filter module may be user replaceable, regular maintenance is generally required to remove contaminant build-up from within both the duct system and the condensate accumulator. Such maintenance can be costly and result in processor downtime.
It is evident that there is a need for improving thermal processors to reduce problems associated with contaminants produced during development of photothermographic film.
In one embodiment, the present invention provides a thermal processor including an oven for thermally developing an imaging media which produces gaseous contaminants during development, the gaseous contaminants including an odorous portion and a condensable portion which condenses at or below a condensation temperature, and a contaminant removal cartridge having a housing configured to selectively couple to the oven. The contaminant removal module includes, within the housing, a heat exchanger and a filter module. The heat exchanger is configured to receive from the oven at least a first air flow at a first temperature, wherein the first temperature is above the condensation temperature, and including gaseous contaminants. The heat exchanger is further configured to cool the first air flow to a desired filtering temperature, which is below the condensation temperature, so as to condense and collect substantially all of the condensable portion of the gaseous contaminants and form a filtering air flow. The filter module is configured to receive the filtering air flow, to collect substantially all remaining condensed contaminants, and to absorb substantially all of the odorous portion of the gaseous contaminants so as to form an exhaust air flow.
In one embodiment, the first temperature is substantially equal to a processing temperature of the oven. In one embodiment, the filter module includes an absorbent material configured to absorb the odorous portion of the gaseous contaminants from the filter air flow such that the exhaust air flow is substantially free of gaseous contaminants. In one embodiment, the desired filtering temperature is approximately equal to a temperature at which the absorbent material is most absorbent. In one embodiment, the desired exhaust temperature is approximately equal to an ambient temperature of an environment in which the thermal processor operates.
During operation of the thermal processor, substantially all condensable and all odor-causing gaseous contaminants produced by the imaging media during thermal development are collected and/or absorbed within the contaminant removal cartridge. Additionally, since the temperature of the first air flow is substantially at the processing temperature of the oven, condensation of gaseous contaminants within the oven or other internal components of processor 30 is substantially eliminated.
When the contaminant removal cartridge needs to be replaced, a user of the thermal processor is able to simply remove and replace the “used” contaminant removal cartridge with a “fresh” contaminant removal cartridge. Since collection of the gaseous contaminants is substantially confined to the user-replaceable contaminant removal cartridge, costly maintenance and downtime associated with cleaning condensed gaseous contaminants from within the thermal processor is substantially reduced. Furthermore, because substantially all of the condensable portion of the gaseous contaminants is collected in the heat exchanger, the effectiveness of the absorbent material is extended, thereby extending an expected life of the contaminant removal cartridge.
The foregoing and other objects, features, and advantages of the invention will be apparent from the following more particular description of the embodiments of the invention, as illustrated in the accompanying drawings. The elements of the drawings are not necessarily to scale relative to each other.
The following is a detailed description of the preferred embodiments of the invention, reference being made to the drawings in which the same reference numerals identify the same elements of structure in each of the several figures.
Contaminant removal cartridge 36 includes a heat exchanger 46 and a filter module 48 positioned within a housing 50 which is configured to enable contaminant removal cartridge 36 to be selectively coupled to and removed from thermal processor 30. In one embodiment, housing 50 of contaminant removal cartridge 36 is configured to slideably insert into and couple to enclosure 32 so as to be proximate to and couple to oven 34 (i.e. an “installed” position). In one embodiment, thermal processor 30 includes an insulation layer 52 positioned between oven 34 and contaminant removal cartridge 36. In one embodiment, when in an installed position, contaminant removal cartridge 36 is positioned so as to maintain an air layer 54 between housing 50 and insulation layer 52. In one embodiment, insulation layer 52 comprises melamine insulation.
Although illustrated and described by
In one embodiment, heat exchanger 46 includes a contaminated air path or duct 56 and a cooling air duct 58 which share and are separated by one or more duct walls 60, illustrated as duct walls 60a and 60b, such that heat exchanger 46 comprises a “separated air-flow” heat exchanger. In one embodiment, duct walls 60 comprise a material having a high thermal conductivity. In one embodiment, ducts walls 60 comprise aluminum. In one embodiment, contaminated air duct 56 is coupled to filter module 48 by a transfer vent 61.
In one embodiment, housing 50 is configured to selectively couple to oven 34 such that an exhaust inlet 62 through housing 50 from contaminated air duct 56 of heat exchanger 46 aligns and couples to an exhaust outlet 64 of oven 34. In one embodiment, as illustrated by
In one embodiment, exhaust fan 68 is configured to create a vacuum that creates an air flow from oven 34 through contaminant removal cartridge 36 and which is exhausted from enclosure 32 of thermal processor 30 via exhaust fan 68. As such, in one embodiment, contaminated air duct 56 of heat exchanger 46 is configured to receive a processor air flow 80 from oven 34 via exhaust outlet 64 and exhaust inlet 62, wherein processor air flow 80 is substantially at the desired processing temperature and includes the gaseous contaminants produced by imaging media 42. In one embodiment, the desired processing temperature is approximately 125° C.
Supply fan 66 is configured to provide a cooling air flow 82 at a cooling air temperature through cooling air duct 58 with cooling air flow 82 entering at cooling air inlet 70 and exiting via cooling air outlet 72 and cooling vent 74 through enclosure 32. In one embodiment, cooling air flow 82 comprises air from an environment in which thermal processor 30 is located. In one embodiment, the cooling air temperature is at an ambient temperature of the environment in which thermal processor 30 is located. In one embodiment, cooling air flow 82 may be provided by an external device (not illustrated) configured to provide chilled air, such that the cooling air temperature is less than the ambient temperature.
As processor air flow 80 flows through contaminated air duct 56 toward filter module 48, heat is transferred from processor air flow 80 to cooling air flow 82 via thermo-conductive walls 60, thereby reducing the temperature of processor air flow 80. When the temperature of processing air flow 80 reaches and drops below the condensation temperature of the condensable portion of the gaseous contaminants (e.g. FAZ), the FAZ and other condensable contaminants begin to condense and collect on the internal surfaces of contaminated air duct 56. In one embodiment, heat exchanger 46 is configured to cool processor air flow 80 such that substantially all of the condensable portion of the gaseous contaminants precipitate and collect on the internal walls of contaminated air duct 56.
In one embodiment, a flow rate of processor air flow 80 and a flow rate of cooling air flow 82 are configured so that a heat transfer rate from processor air flow 80 to cooling air flow 82 is such that filtering air flow 86 is at a temperature substantially equal to a desired filter temperature as it enters filter module 48 via transfer vent 61 from heat exchanger 46. In one embodiment, the flow rate of cooling air flow 82 ranges from five to fifteen times the flow rate of processor air flow 80.
In one embodiment, as illustrated by
In one embodiment, absorbent block 88 comprises an absorbent material configured to absorb the odor-causing portion of the gaseous contaminants, including MEK, for example, as filtering air flows 94 are drawn through to exhaust manifold 92. In one embodiment, absorbent block 88 comprises activated carbon. In one embodiment, absorbent block 88 most effectively absorbs odor-causing contaminants when operating at or below a maximum operating temperature. In one embodiment, absorbent block 88 has a maximum operating temperature of approximately 50° C.
As such, in one embodiment, heat exchanger 46 is configured to provide filtering air flow 86 at a desired filter temperature which is at or below the maximum operating temperature of absorbent block 88. In one embodiment, heat exchanger 46 provides filtering air flow 86 at a desired filter temperature which is at or below approximately 50° C.
In one embodiment, in addition to absorbing the odor-causing portion of the gaseous contaminants, filter module 48 is configured to collect substantially all condensed contaminants (e.g. FAZ) that may be remaining in filtering air flow 86. As such, in one embodiment, exhaust manifold 92 of filter module 48 is configured to receive filtering air flows 94 after passing through absorbent block 88 and to provide an exhaust air flow 96 from thermal processor 30 via exhaust vent 76 and exhaust fan 68, where exhaust air flow 96 is substantially free of gaseous contaminants. It is noted that filter module 48 absorbs heat from filtering air flows 86 and 94 such that exhaust air flow 96 is at a temperature which is less than the desired filter temperature.
As described above, during operation of thermal processor 30, substantially all condensable gaseous contaminants (e.g. FAZ) and all odor-causing gaseous contaminants (e.g. MEK) produced during thermal development of imaging media in oven 34 are collected and/or absorbed within contaminant removal cartridge 36. Additionally, since contaminant removal cartridge 36 is positioned proximate to oven 34 to minimize the travel distance of processor air flow 80 from oven 34 to heat exchanger 46, the temperature of processor air flow 80 is substantially at the desired processing temperature upon entering contaminated air duct 56, thereby substantially eliminating condensation of gaseous contaminants within oven 34 or other internal components of processor 30.
When contaminant removal cartridge 36 has collected an amount of gaseous contaminants such that it begins to lose its effectiveness, such as after predetermined number of operating hours or after a certain amount of imaging media has been thermally developed, a user of thermal processor 30 is able to simply remove and replace a “used” contaminant removal cartridge 36 with a “fresh” contaminant removal cartridge. Since collection of gaseous contaminants is substantially confined to user-replaceable contaminant removal cartridge 36, costly maintenance and downtime associated with cleaning condensed gaseous contaminants from thermal processor 30 is substantially reduced. Additionally, because substantially all of the condensable portion of the gaseous contaminants is collected in heat exchanger 46, absorbent block 88 does not become quickly coated with condensable contaminants so that the effectiveness of absorbent block 88 is extended, thereby extending the life of contaminant removal cartridge 36.
In one embodiment (not illustrated) housing 50 includes a grip or handhold mechanism 98, such as a handle, for example, to enable a user to more easily couple/de-couple contamination removal cartridge 36 to/from thermal processor 30. In one embodiment, housing 50 comprises ABS plastic, which reduces a weight and cost of contaminant removal cartridge 36.
Processor 130 includes an overall enclosure 132, an oven 134, and a contaminant removal cartridge 136. Oven 134 includes a drum processor section 200 that functions as a pre-dweil section, a flatbed processor section 202 that functions as a dwell section, and a cooling section 204. An imaging media, such as imaging media 142, is thermally developed by thermal processor 130 by moving imaging media 142 along a transport path 143 (illustrated by a heavy line) through drum processor 200, flatbed processor 202, and cooling section 204.
Contaminant removal cartridge 136 includes a heat exchanger 146 and a filter module 148 (see
Drum processor section 200 includes a circumferential heater 206 positioned within an interior of a rotatable processor drum 208 that is driven so as to rotate as indicated by directional arrow 210. A plurality of pressure rollers 212 is circumferentially arrayed about a segment of processor drum 208 so as to hold imaging media 142 in contact with processor drum 208 as it rotates and moves imaging media 142 along transport path 143. In one embodiment, circumferential heater 206 heats processor drum 208 to a desired pre-dwell temperature. In one embodiment, the pre-dwell temperature is within a range from approximately 120° C. to approximately 135° C. In one embodiment, the desired pre-dwell temperature is approximately 125° C.
Flatbed processor 202 includes a plurality of rollers, such as illustrated at 220, positioned to form a planar path through flatbed processor 202. One or more rollers 220 are driven to move image media through flatbed processor 202 along transport path 143. A pair of idler rollers, 222a and 222b, are positioned to form a nip with a corresponding roller to ensure that imaging media 142 remains in contact with rollers 220 and does not lift from transport path 143.
Flatbed processor further includes a heat source 224 (e.g. a resistive heat blanket) and a heat plate 226 to heat imaging media 142 as it moves through flatbed processor 202. In one embodiment, as illustrated in
In one embodiment, as illustrated by
A system similar to that described above employing internal passages for exhausting air from flatbed processor 202 is described in U.S. Pat. No. 5,895,592 to Struble et al., assigned to the same assignee as the present invention, which is herein incorporated by reference. In one embodiment, the internal exhaust air passages also exhaust air from a junction region between drum processor 200 and flatbed processor 202 where transport path 143 transitions from processor drum 208 to rollers 220 as gaseous contaminants trapped between imaging media 142 and processor drum 208 are released in this region.
Cooling section 204 includes a plurality of transport rollers 230 to move imaging media 142 through cooling section 204 and a pair of nip rollers, 232a and 232b, to direct imaging media 142 out of cooling section 204 along transport path 143. Cooling section 204 is configured to cool imaging media 142 from the processing temperature of flatbed processor 202 so as to cause thermal development of imaging media 142 to cease.
In one embodiment, as illustrated by
Processor air flow 180 enters contaminated air duct 156 via exhaust inlet 162 and combines with cooling section air flow 181 entering contaminated air duct 156 via exhaust inlet 163 to form a filtering air flow 186 which is directed to filter module 148 (see
Exhaust fan 168 draws processing air flow 180 and cooling section air flow 181 into heat exchanger 146 to form filtering air flow 186, and draws filtering air flow 186 through filter module 148 to form exhaust air flow 196. In one embodiment, exhaust fan 168 causes processing air flow 180 and cooling section air flow 181 to each flow at a rate of approximately 1 CFM (cubic feet per minute) such that filtering air flow 186 and exhaust air flow 196 each flow at a rate of approximately 2 CFM. A supply fan 166 provides cooling air flow 182 through cooling air duct 158 from cooling air inlet 170 to cooling air outlet 172. In one embodiment, supply fan 166 provides cooling air flow 182 at a flow rate of approximately 10 CFM.
As processing air flow 180 travels through contaminated air duct 156, heat is transferred to cooling air flow 182 via thermally conductive duct wall 160a. In one embodiment, as processing air flow 180 merges with cooling section air flow 181 to form filtering air flow 186, the temperature of processing air flow 180 is approximately equal to the temperature of cooling section air flow 181. As filtering air flow 186 travels through contaminated air duct 156, heat continues to be transferred to cooling air flow 182 via duct walls 160a and 160b such that the temperature of filtering air flow 186 is substantially equal to a desired filter temperature. In one exemplary embodiment, wherein processing air flow 180 has a temperature of approximately 125° C., cooling section air flow 181 has a temperature of approximately 80° C., and cooling air flow 182 has an ambient temperature of approximately 40° C., heat exchanger 146 is configured to provide a filtering air flow 186 to filtering module 148 having a temperature at or below 50° C.
In a fashion similar to that described above with reference to
Filter module 148 includes an absorbent block 188, an intake manifold 190, and an exhaust manifold 192. In one exemplary embodiment, absorbent block 188 is a block of granulated activated charcoal. In one embodiment, intake and exhaust manifolds 190 and 192 each consist of an open-cell foam material. As filtering air flow 186 enters intake manifold 190 via transfer vent 161, intake manifold 190 serves to provide a substantially evenly distributed air pressure across a surface 187 of absorbent block 188 so that filtering air flow 186 is pulled in a substantially even fashion across a cross-section of absorbent block 188 by exhaust fan 168. This evenly distributed filtering air flow is illustrated by multiple air flows 194.
Similarly, exhaust manifold 192 serves to provide a substantially evenly distributed air pressure across a surface 189, which is opposite absorbent block 188 from surface 187. Exhaust manifold 192 receives filtering air flows 194 after passing through absorbent block 188 and provides exhaust air flow 196 to exhaust fan 168.
In a fashion similar to that described above with reference to
In one exemplary embodiment, housing 150 is constructed of a plastic material having thermal characteristics such that the housing will not degrade when exposed to the processing temperatures associated with thermal processor 130. In one embodiment, the housing consists of glass-filled polycarbonate. In one embodiment, housing 150 consists of a combination of plastic and metal. In one embodiment, duct walls 160a and 160b are constructed of a material having high thermal conductivity characteristics. In one embodiment, duct walls 160a and 160b are constructed of aluminum. In one embodiment, housing 150 includes a handle 198 which enables a user to more easily insert/remove contaminant removal cartridge 136 into/from thermal processor 130.
Filtering air flow 186 enters intake manifold 190 from contaminated air duct 156 (see
The corrugated shape of duct walls 160a and 160b and fins 242 cause processing air flow 180 and filtering air flow 186 to travel in an undulating or serpentine fashion through contaminated air duct 156 before exiting to filter module 148 via transfer vent 161. Similarly, the corrugated shape of duct walls 160a and 160b causes cooling air flow 182 to travel in a serpentine fashion through cooling air duct 158 from cooling air inlet 170 to cooling air outlet 172. The corrugated shapes of contaminated air duct 156 and cooling air duct 158 increases the travel distance of processing air flow 180, cooling air flow 182, and filtering air flow 186 through heat exchanger 146 and increases the contact area of duct walls 160a and 160b between of contaminated air duct 156 and cooling air duct 158. As a result of the corrugated shape and serpentine air flows, heat exchanger 146 is able to be more efficiently and more effectively transfer heat to cooling air flow 182 from processing air flow 180, cooling section air flow 181, and filtering air flow 186 than if employing planar duct walls.
The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.
