Patent Application
20060151457
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 an entrance guide 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. Once the film has been subjected to photostimulation, for example, by light from a laser of a laser imaging system, 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 slides the photothermographic film over flat, heated surfaces or plates. Still 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.
Each of these processors heats 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, which may subsequently condense when coming in contact with cooler air or surfaces within the processor. This is particularly true at the location where the photothermographic film enters a processor where external ambient air may be drawn into the processor. When contacting cooler air or 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. As such, regular maintenance may be required to address problems resulting from such contaminants, which 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 image in a media, the oven having an entrance, and a guide positioned at the oven entrance. The guide includes a receiver having a major surface configured to contact and receive the media, and a separator configured to lift and separate the media from at least a portion of the major surface and to direct the media into the oven.
In one embodiment, the present invention provides a thermal processor. The thermal processor includes an oven for thermally developing an image in a media, wherein the media emits gaseous contaminants as the media moves through the oven from an entrance to an exit during development, the gaseous contaminants having a condensation temperature. A guide is positioned at the oven entrance and configured to direct the media into the oven. The guide includes a major surface configured to receive the media and a plurality of lift elements configured to separate the media from at least a portion of the major surface so as to form at least one collection area on the major surface not in contact with the media, the at least one collection area configured to have a temperature not exceeding the condensation temperature such that the gaseous contaminants condense and collect on the at least one collection area.
By forming at least one collection area not in contact with the media in which the gaseous contaminants collect and deposit, the likelihood that contaminants will deposit on the imaging media and other processor surfaces is reduced. As a result, the likelihood of image artifacts caused by condensed contaminants is reduced and maintenance requirements are also reduced.
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.
Upper and lower covers 50 and 52 have respective first ends 56 and 58 spaced from one another to define a media (film) entrance region 60, and respective second ends 62 and 64 forming a media (film) exit region 66. Upper cover 50 can be rotated around a hinge 68 so that enclosure 48 can be opened to allow access to drum 42 and pressure rollers 46. A film diverter 70 diverts film from contact with drum 42 to exit region 66 over a perforated felt pad 72.
An upper condensation trap 74, lower condensation trap 76, and flexible duct 78 form a portion of contaminant removal system 40. As illustrated by the dashed lines in
Entrance region 60 includes a pair of feed rollers, 88a and 88b, and an entrance guide 90 according to one embodiment of the present invention.
During operation, drum 42 is heated to a temperature necessary to provide a uniform development temperature to the imaging media being developed. For photothermographic medical film, for example, drum 42 operates at a temperature of approximately 122.5° C. In one embodiment, drum 42 is heated by a circumferentially uniform resistive heater mounted within drum 42. Drum 42 heats pressure rollers 46, oven 54, and other processor components including guide plate 92 and lift elements 102 of entrance guide 90.
Feed rollers 88a and 88b receive a piece of imaging media, such as imaging media 104, at an ambient temperature and form a nip to feed imaging material to drum 42. Entrance guide 90 receives imaging media 104 along leading edge 96, and together with guide plate 100, channels imaging media 104 toward drum 42. In one embodiment, media ramp 94 (e.g., lift elements 102) is positioned so that imaging media 104 contacts drum 42 at a desired angle (θ) 106 (see
Photothermographic film, such as imaging material 104, generally comprises a base material, such as a thin polymer or paper, which is typically coated on side with an emulsion of heat sensitive materials. As imaging media 104 enters oven 54 and begins to wrap around drum 42, imaging media 104 begins to be heated to the desired development temperature. As the emulsion is heated, it produces gasses containing contaminants, fatty acids (FAZ) in particular, that may subsequently condense on processor surfaces having temperatures at or below a corresponding condensation temperature of the gasses.
In efforts to remove these airborne contaminants, vacuum system 80 draws air into oven 54 from entrance region 60 and produces upper and lower air streams 110 and 112 around drum 42, as illustrated in
As described above, entrance guide 90, including guide plate 92 and lift elements 102, are heated by drum 42. Also as described above, entrance guide 90 receives imaging media 104 at leading edge 96 and directs imaging media 104 to heated drum 42. As imaging media 104 moves across major surface 93 of guide plate 92, imaging media 104 absorbs heat from guide plate 92, causing guide plate 92 to become cooler than interior components of thermal processor 30, such as drum 42 and pressure rollers 46. In one embodiment, guide plate 92 comprises a material having a high thermal conductivity such that as imaging material 104 absorbs heat from guide plate 92, the temperature of guide plate 92 is reduced to a level not exceeding the condensation temperature of gases produced by the emulsion of imaging media 104. In one embodiment, guide plate 92 comprises a metal, such as stainless steel.
As imaging media 104 contacts and slides across lift elements 102, lift elements 102 separate and lift imaging media 104 away from major surface 93 of guide plate 92, forming a plurality of collection areas 108 adjacent to lift elements 102 on major surface 93 of guide plate 92 that are not in contact with imaging media 104. In one embodiment, lift elements 102 comprise a material having a low thermal conductivity, such that lift elements 102 transfer minimal amounts of thermal energy to imaging material 104 and maintain a temperature above the condensation temperature of gasses produced by the emulsion of imaging media 104. In one embodiment, lift elements 102 comprise a polycarbonate material.
Since guide plate 92 is maintained at a temperature less than the condensation temperature, collection areas 108 are also at or below the condensation temperature. Therefore, the gases produced by imaging media 104 as it enters oven 54 and begins to wrap around and be heated by heated drum 42 condense and deposit on collection areas 108. Additionally, since lift elements 102 are maintained above the condensation temperature, the gaseous contaminants produced by imaging media 104 do not condense on lift elements 102. As such, the gasses and associated contaminants produced in the vicinity of entrance region 60, FAZ in particular, condense and deposit in collection areas 108 on the surface of guide plate 92 and do not deposit on imaging media 104 or other surfaces.
By forming collection areas 108 that are not in contact with the imaging media and by maintaining these areas at temperatures not exceeding the condensation temperature; entrance guide 90 according to the present invention controls the locations where FAZ and other gaseous contaminants will condense and deposit. As such, entrance guide 90 reduces the likelihood that such contaminants will be deposited on the imaging media and, as a result, reduces the occurrence of image artifacts caused by contaminants deposited on the film. It also reduces the likelihood that such contaminants will be deposited on other processor surfaces, thereby reducing maintenance requirements and further reducing potential sources of image artifacts.
A pair of feed rollers 188a and 188b receive a piece of imaging material, such as imaging material 204, and form a nip to feed imaging material 204 to oven 156. Entrance guide 190 includes a guide plate 192 and a media ramp 194. Guide plate 192 has a leading edge 196 and a trailing edge 198 positioned within oven 156. Ramp 194 extends angularly from guide plate 192 along trailing edge 198 and is positioned substantially within oven 156. A guide plate 200 is positioned in a parallel with guide plate 192 and together with entrance guide 190 channel imaging media 204 into oven 156. In one embodiment, media ramp 194 is positioned such that imaging media 204 enters oven 156 at a desired angle relative to rollers 172 and 174.
In a fashion similar to that described above with respect to the drum-type processor illustrated by
All documents, patents, journal articles and other materials cited in the present application are hereby incorporated by reference.
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.
