This invention relates generally to the processing of photosensitive sheet material and more particularly is concerned with the processing of photosensitive sheet material with a relatively small amount of liquid processing solution, such as developer solution.
Photosensitive sheet material (PSM) as used herein and with which this invention is concerned is intended to include a substantially flexible base sheet or web and a coating of photographic emulsion carried on at least one of the major faces of the sheet. Commonly, the emulsion includes a plurality of layers wherein each layer is designed to produce a specific result when allowed to react with developer solution. For example, in the photographic art, reproduction of an image is commonly accomplished by exposing a photosensitive material such as, for example, a photographic film or paper, to light reflected from an object or image, and then the exposed PSM is thereafter developed to produce a reproduction, i.e., print of the image. Development of such flexible PSM commonly includes the subjecting of the PSM to a series of processing steps, such as immersing the emulsion-carrying face in a developer solution to bring forth the desired image.
Developer solutions comprise combinations of chemicals, generally in aqueous solution, wherein each of the chemicals is chosen to react with one or more of the constituents in one or more of the layers of the emulsion to produce a specific result. The quality of the resulting product depends, to a large extent, upon the nature of the physical contact of the PSM with the developer solution. However, chemical reactions which occur during development of a PSM generate by-products that are taken up in the developer solution which, in turn, renders the developer solution less effective. Therefore, it is important that during a development process, developer solution in contact with the PSM be cyclically exchanged to continuously expose the PSM to fresh or less-depleted solution.
The type of apparatus with which this invention is concerned includes a reservoir cell including an internal cavity for containing a processing solution, such as a developer solution, so that the body of solution contained within the cell cavity is substantially sheet-like in form (a continuous layer). During a processing step with such a reservoir cell, a PSM is routed edgewise through an opening provided in the reservoir and into the body of solution contained therein and conveyed through the cavity so that the processing solution acts upon the PSM in a desired manner and for a predetermined period of time. The apparatus may include a series of such reservoir cells arranged in a side-by-side arrangement so that conveyance of a PSM in sequence through the cells exposes the PSM in succession to the working fluid contained within each cell. The number of cells and the characteristics of the solution contained within each cell depends upon the characteristics which the PSM is desired to exhibit when processed. In addition, the rate at which the PSM is conveyed through any one cell and the rate of replenishment of the fluid contained within the one cell are commonly coordinated to control the exposure of the PSM to the working fluid within the one cell.
A reservoir cell of the aforedescribed class is shown and described in co-pending patent application Ser. No. 07/679,762, now U.S. Pat. No. 5,266,994, the disclosure of which is incorporated herein by reference. In one embodiment of the reservoir cell described in the referenced application, there is provided a plurality of elongated woven fabric loops which are secured to the upper part of the reservoir cell so that the bight of the loop extends downwardly into the reservoir cavity. A PSM which is moved through the cavity of such a cell slidably moves in contact with the underside of the loops so that the volumetric amounts of developer solution in contact with the emulsion is replaced with fresh or less-depleted volumetric amounts of developer solution. Heretofore, however, the distribution of replacement solution throughout the cavity was, to a large extent, unpredictable. It would therefore be desirable to provide a reservoir cell wherein the distribution of replacement solution with depleted solution through the cell cavity improved.
There are many processing chemicals, e.g., those which possess a pH greater than 11.0, which are highly susceptible to oxidation when exposed to air. When such a chemical remains within a cell of the aforedescribed class for a prolonged period of time, such as overnight, the chemical loses some of its effectiveness and may be rendered undesirable. It would be desirable to provide a reservoir cell wherein the likelihood of oxidation of processing solution contained within the cell cavity is substantially reduced so that if the solution is left within the cell for a prolonged period of time, the effects of oxidation of the solution are also reduced.
It is also well known that photographic processing operations are quite sensitive to temperature changes. Depending upon the process, temperatures may need to be held within ranges of between .+-.0.5.degree. F. to .+-.2.0.degree. F. from a base temperature for consistency and optimum results. In processing applications of the type with which this invention is concerned, i.e., those involving a relatively small amount of liquid processing solution, and especially solution disposed in a sheet-like form, an appreciable differential between the temperature of a reservoir cell and that of the working fluid introduced into the cell may alter, e.g., cool, the temperature of the introduced working fluid to such an extent that the temperature of the process operation is outside of an acceptable range. It would therefore be desirable to provide a reservoir cell wherein the temperature of the working fluid contained therein can be accurately controlled.
An aspect of the present invention is to provide a new and improved system and method utilizing a reservoir cell of the aforedescribed class wherein the distribution of processing solution throughout the cell cavity is enhanced.
Another aspect of the present invention is to provide a new and improved reservoir cell of the aforedescribed class which reduces the likelihood of aerial oxidation of processing solution contained within the cell cavity.
Still another aspect of the present invention is to provide a new and improved system and method utilizing a reservoir cell of the aforedescribed class wherein the temperature of the working fluid contained within the cell can be accurately controlled.