PHOTOGRAPHIC APPARATUS

Abstract: Apparatus for treating photographic film or paper with a fluid comprises means for defining a thin fluid treatment channel (48) for receiving the web and having at least one pair of elongated juxtaposed fluid injection openings (34, 36) for injecting fluid into said channel (48) on opposite sides of the web and at least one pair of elongated evacuation openings (38, 40) on opposite sides of the web in spaced relationship with the injection openings. Means are provided for supplying treatment fluid under pressive to the injection openings (34, 36) to inject treatment fluid under pressive into the channel (48) on opposite sides of the web to support the web and to establish a high velocity laminar flow of treatment fluid from the injection openings (34, 36) to the evacuation openings (38, 40), the evacuation openings (38, 40) being spaced from the injection openings (34, 36) by a predetermined distance to effect discharge of fluid from the channel (48) when the fluid boundary layer reaches a predetermined thickness to maintain a mass transfer rate in the fluid which exceeds the mass transfer rate in the web.

Description: PHOTOGRAPHIC APPARATUS Technical Field This invention relates to apparatus for transferring thermal energy or chemical mass through a fluid medium and, more specifically, to such transfer in the processing of light sensitive material such as photographic film or paper. Background Art Conventional film (or paper) processing devices do not provide a sufficient level of agitation at the film-liquid interface. As a result, a layer of liquid that is depleted of reactants and enriched in reaction by-products exists at the film surface. This layer is the chemical boundary layer. During photographic processing, this boundary layer can influence both the rate at which photochemicals are transferred to and from the film, as well as their concentrations within the film. Either influence can affect the rate and quality of processing. An analogous thermal boundary layer, a region of reduced temperature, is created in the layer of gas which exists at the film surface during the drying portion of the processor. Analysis and experimental measurements of conventional processors indicate that boundary layers exist which are thick enough so as to become the processing rate limiting parameter. More specifically, the transfer of chemicaL mass and heat energy through the chemical and thermal boundary layers occurs more slowly than transfer through the film itself. This condition results in low processing speeds, excessively long processing paths and increased size of the processor, including the dryer section. Also, the chemical concentrations in the processor boundary layer need to be excessively high to maintain reasonable mass transport rates resulting in inefficient utilization of the processing chemicals. In the dryer section of the processor drying, temperatures need to be excessively high to maintain reasonable film drying rates resulting in inefficient utilization of thermal energy. The rate of chemical mass transfer through this boundary layer to the film surface can be approximated to the first degree by the following equation: where: = Mass Transfer Rate (Grams/sec) A = Film Area (cm-2) D = Chemical Diffusivity (c ^/sec) δ = Boundary Layer Thickness (cm) ΔC = Concentration Gradient (Grams/CM^) The ratio of diffusivity/delta is typically called the mass transfer coefficient. A high mass transfer coefficient will result in a high chemical mass transfer rate, for a given concentration difference between the film and bulk solution concentration. Diffusivity is a function of such variables as molecule size and temperature. While diffusivity can easily be increased by increasing processing solution temperatures (thereby increasing chemical mass transfer rates) , this involves the use of complicated equipment and increased cost of processing. Alternatively the chemical mass transfer rate can be increased by decreasing the chemical boundary layer thickness independent of increasing temperature. It is known in the prior art that increased agitation decreases boundary layer thickness and that decreased boundary layer thickness produces an increase in developed film density. Also it is know that increased temperatures increase chemical diffusivity. Further, it is known that treating film with a continuous spray (jet impingement) or turbulent flows provides a high degree of agitation, and high reductions in boundary layer thickness. The paper "Heat Transfer Characteristics of Impinging Two- Dimensional Air Jets," Gordon and Akfirat, Journal of Heat Transfer. February 1966, pages 101-108, outlines studies of impinging air jets in the heat transfer domain. The results reported indicate that very high heat transfer coefficients can be obtained through the use of direct impinging jets, that the high heat transfer coefficient falls off quite rapidly with increasing distance from the center or stagnation point of the impinging jet, and that the rapid fall off produces an average coefficient over a longer area of impingement that is substantially less than the maximum value. Typically high turbulent flow rates or jet impingement have been used to achieve adequate mixing. The problem with increasing agitation through turbulence or with jet impingement is that it is extremely difficult to achieve uniformity of the treatment process since any non-laminar fluid condition contains non-uniform fluid disturbances such as pockets of turbulence, eddy currents, etc. Also turbulent flows dissipate a great deal of energy in places where it does no useful work, specifically areas away from the film surface. This is due to the high "shearing" action that occurs within the turbulent flow field. Moreover, with turbulent flows and jet impingement it is difficult to treat large areas where uniformity is ever a greater problem. For the above reasons processors in current use are typically roller transport processors where film or paper is transported by rollers through a tank of solution. While such processors provide more uniform processing than impinging jets or turbulent flows, they are massive in size, inefficient and thus subject to the boundary layer problems discussed above. Disclosure of the Invention It is an object of the invention to provide a processor which minimizes the above effects by providing laminar flow of a web treating liquid or gaseous fluid and reducing the rapid build up of the boundary layer and subsequent decrease in chemical or heat transfer rate. In a preferred embodiment this object is accomplished by providing a means which defines an elongated channel for receiving a web (in continuous or sheet form) to be treated with a fluid. The fluid is injected into the channel at one or more injection sites. Fluid is evacuated from the channel at spaced evacuation sites. Each injection site is positioned between two evacuation sites and spaced therefrom such that fluid will flow from the injection site to the evacuation sites with laminar flow and be evacuated when the boundary layer of the fluid reaches a predetermined minimum thickness. Brief Description of the Drawings In the detailed description of the embodiments of the invention presented below, reference is made to the following drawings wherein: Fig. 1 is a perspective view in partial section illustrating a portion of a parallel plate processor in accordance with the invention; Fig. 2 is a schematic sectional view illustrating the basic fluid circulation paths of a parallel processor in accordance with the invention; Fig. 3 is a section showing the end wall and . exit or entrance of the processor illustrated in Fig. 2; Fig. 4 is a schematic illustration of a plurality of serially arranged processors; Fig. 5 is a sectional view illustrating another embodiment of the parallel plate processor; Fig. 6 is a partial sectional view illustrating the application of the embodiment shown in Fig. 5 to the processing of light sensitive material; Fig. 7 is a graph illustrating boundary thickness of the processor illustrated in Fig. 2 compared with the boundary layer thickness of a prior art processor; Fig. 8 is a force curve illustrating the stabilizing action of the fluid cushions; Fig. 9 is a perspective view of a dryer for photographic film or paper in accordance with the invention; Fig. 10 is a cross section of the air bearings shown in Fig. 9; Fig. 11 shows actual measured heat transfer coefficient values for the apparatus depicted in Figs. 9 and 10 when constructed with a 4cm wide bearing versus the impingement jet system of a commercially available dryer; Fig. 12 is an exploded perspective view of a portion of a film dryer illustrating still another embodiment of the invention; Fig. 13 is a view similar to Fig. 12 with parts omitted to show the construction in more detail; Fig. 14 is a plan view of the manifold arrangement shown in Fig. 12 with the cover plate partially cutaway; Fig. 15 is a section taken along the line 15- 15 of Fig. 14; Fig. 16 is an enlarged detail of the area 205 of Fig. 15; Fig. 17 is a plan view of the injection and evacuation openings of the dryer depicted in Figs. 12 and 13 with arrows indicating the fluid flow paths; Fig. 18 is a side view showing the corrugation of the web while transported through the dryer depicted in Figs. 12 and 13; Fig. 19 is side view of an assembled dryer of the type shown in Figs. 12 and 13 with film transport rollers; Fig. 20 is a schematic illustration of another embodiment of the dryer shown in Figs. 12 and 13; Fig. 21 is a sectional view of a film processor in accordance with still another embodiment of the invention with the fluid conduits depicted schematically; Fig. 22 is a schematic illustration of a film processor in accordance with still another embodiment of the invention; Fig. 23 is a perspective view of a processor in accordance with still another embodiment of the invention with the top removed and a portion of the sidewalls cut away to illustrate internal parts; Fig. 24 is an exploded perspective view of the processor shown in Fig. 23; Fig. 25 is an elevation view of portions of apparatus such as depicted in Figs. 23 and 24 illustrating the transport of film between two processor tanks; Fig. 26A-G are front views of the manifold plates or walls of the processor depicted in Figs. 23 and 24; Fig. 27 is a front view of the processor shown in Fig. 23 partially cut away to show the pump chamber; Fig. 28 is a side view of the processor shown in Fig. 23 partially cut away to show the pump chamber; Fig. 29 is an enlarged view of the bottom group of hydrostatic bearings of the processor shown in Fig. 23; Figs 30 and 31 are enlarged perspective views of portions of a hydrostatic bearing used in the processor of Fig. 23; Fig. 32A-C are enlarged cross-sections showing three configurations of the hydrostatic bearing used in the processor of Fig. 23; and Fig. 33 is a side view of the hydrostatic bearings of another embodiment of the processor depicted in Fig. 23. Mode of Carrying Out the Invention Embodiments of Figs. 1-8 While the invention will be disclosed in connection with the treatment of light sensitive materials, it is to be understood that the invention is applicable to any treatment process that is rate limited by the diffusion of chemicals or chemical energy through an adjacent aqueous or gaseous boundary layer or to any process that is rate limited by the transfer of heat through an adjacent thermal boundary layer. Also, it is to be understood that the term "fluid" encompasses both gaseous and liquid mediums including air and water. Referring to Fig. 1 of the drawings, there is shown a basic parallel plate processor 8 for circulating a processing fluid into contact with light sensitive material such as a photographic film (or paper) F. The processor illustrated in Fig. 1 comprises a pair of spac ;d parallel plates 10, 12 defining a channel 13 for the transport of the film F therebetween. The plates are supported by front and rear end walls 14 and are provided with juxtaposed solution injection ports or slits 16, 18 defining a fluid injection site for injecting solution under pressure into channel 13 on opposite sides of the film F. A pair of manifold plates 20, 22 having openings 24, 26 aligned with injection slits 16, 18 respectively are attached to the processor plates 10, 12 for supplying solutions to the injection slits. Alternatively, the manifold plates 20, 22 may be replaced with a direct feeding manifold such as that shown in Fig. 5. The system plumbing has been omitted to clarify the basic boundary layer concept. The basic solution flow path is indicated by the arrows in Fig. 1. Fluid under pressure will enter channel 13 on both sides of the film F and create a fluid cushion under pressure on opposite sides of the film which will support the film and permit it to be transported through the channel 13 without contact with the plates 10, 12. The fluid will move to the ends of the channel 13 with a laminar flow where it will be discharged. If the treating fluid is a liquid, it may be collected in a sump (not shown) and be recirculated to the manifold by pumps and conduits (also not shown) . Also, the solution may be replenished as described below. It will also be apparent that the processor may be used in a submerged state similar to the processor disclosed in Fig. 5 and 6. The fluid cushions on opposite side of the film apply pressure forces to the film which tend to stabilize it and support it in a position centered between the plates 10, 12. More specifically, if the film attempts to move off center, it will move closer to one plate than the other. The closer spacing to the one plate will decrease the thickness of the flow channel on that side of the film and decrease the flow . within the channel on that side. The reduced flow rate will decrease the drop in pressure across the injection opening on that side of the film. This will increase the fluid pressure in the thinner channel relative to that of the thicker channel producing a net force on the film tending to restore it to its center position. This stabilizing concept is illustrated by the curve depicted in Fig. 8 which is a plot of force (Dynes) exerted against the film vs film distance from the center of the channel. In accordance with the invention, the length L of channel 13 on each side of the injection slits will have a finite length related to the increase in thickness of the chemical boundary layer 13, so that the solution is discharged at the ends of the channel 13 when the boundary layer reaches a thickness at which the solution is no longer efficiently transferring chemicals (or heat) . More specifically, in the region of the injection slits 16, 18, maximum transfer will occur. However, as the solution moves away from the injection slits in the paths depicted by the arrows, the chemical boundary layer B will gradually increase in thickness as indicated in Fig. 2. At the point where the boundary layer has a thickness which renders the chemical or heat transfer efficiency less than a desired value, it is preferably discharged at the ends of the channel 13 and recirculated or replenished. This concept thus maximizes the effectiveness of the chemical or heat transfer process. The effectiveness of the chemical or heat transfer process is enhanced in two ways. First by minimizing the length L, the distance over which the boundary layer is permitted to develop. Second, the system parameters are selected to establish reasonably high fluid velocities in the laminar fluid flow region to minimize the rate at which the boundary layer is allowed to grow. A small plate separation is used to achieve high fluid velocities with laminar flow. Short distance and high velocity laminar flow result in a slowly developing boundary layer and efficient chemical or heat transfer with laminar flow. The invention uniquely uses laminar flow to advantageously achieve chemical mass or heat transfer rates that actually exceed those provided by all but the most turbulent flows at a fraction of the power requirements. The power requirements are very low because most of the fluid flow energy is dissipated at the film surface due to shear forces between the liquid and the film. This is a unique alternative to the use of turbulent flows which dissipate their flow energy through shear forces within the fluid itself—not at the film surface. The length of the fluid path L was determined in the following manner. It was assumed that the similarities between heat and mass transfer permit conclusions derived from heat transfer studies render conditions of incompressible flow to be extended to the transfer of chemical mass in the liquid domain. There are several ways to specify the effectiveness of heat or chemical mass to transfer. As disclosed in Fluid Dynamics and Heat Transfer, Knudsen and Katz, McGraw Hill, 1958, p. 366, Eg. 13-12, the heat-transfer coefficient h^eat °f a laminar flow along a surface as a function of x (distance from leading edge of a flow path) may be expressed by the following equation: i-_ = K r ° 1 1 3 bθΛC 0.893 l 9αx J where: K = thermal conductivity α = thermal diffusivity = K/CpP c = slope of velocity profile = u ∞ /y U oo = velocity of fluid parallel to the surface y = distance from surface Cp = specific heat of fluid P = Fluid Density To develop the mass transfer analogy the following assumptions can be made: For water: C p P = 1; α = K For liquid: K = D (chemical diffusivity) Therefore the chemical mass transfer coefficient may be expressed by the following equation: This equation defines the relationship between the chemical mass transport coefficient and relevant device fluid properties for the specific parallel plate flow concept incorporated into the processor of Fig. 1 and other embodiments described below. From this equation it can be determined what variables might be manipulated to maximize this coefficient and resulting mass transfer rate. Specifically, this invention involved the realization that hc jj -gM is maximized by increasing u, decreasing y and decreasing x. If it is assumed that a typical processing fluid temperature is 95 degrees Fahrenheit then the following variables have the values indicated: D = 5.0 x 10 ~6 cm 2 /sec U oo = 25.4 cm/sec y .075 cm It will be apparent that hcHEM 1 *-* ) will increase as x increases. An average value of hcnEM over the distance L can be obtained by integrating hc HEM ( ) over a distance X = L as follows: , r -D 2 u_, n/ , If L is assumed to have a value of 1.0 cm, then - - ι ιr-r (5 l0 ^/sec> 2 < 25 - 4CT /. cc 3 n m - L .« t L (i.oαn) (.075 0 1?) R = .0030°"/ sec The table set forth below indicates ranges for the system variables from which minimum, maximum and nominal values of chemical mass transfer coefficients were computed. u∞ y x For Max hcHEM Nominal h_;jj * EM (variables set forth above) Min hc HEM : U*» 20 cm/sec y 0.10 cm x = 2.5 cm kCHEM = .0018 cm/sec Considering the above data it is apparent that a chemical mass transfer value in the following range achieves optimum results for the invention: . ~10~-/ aβc ≥R CHEM .001 βB / 1Iβc This range is based on a chemical diffusivity D equal to 5.0 x 10 ~ ^cm2/sec. Other chemical species would have different values, even within the same solution and it is to be understood that there is a separate distinct boundary layer for each chemical species. This mathematical determination of the relevant dimensions thus resulted in a fluid treatment apparatus having laminar fluid flow while maximizing the efficiency of the treating fluid by preventing increase of the boundary layer thickness beyond a predetermined value. Preferably the maximum thickness is such as to maintain an aqueous chemical mass transfer rate that exceeds the transfer rate within the film by a reasonable design margin.To compare the value of h^jjEM with what one might expect to achieve in conventional tank and roller transport processing the hydrodynamics of roller transport processing was considered to be analogous to flow of liquid over a stationary flat plate. The equations which dictate the chemical mass transfer coefficient for this condition are disclosed in Fluid Dynamics and Heat Transfer, Knudsen and Katz, McGraw- Hill, 1958, p.482, Fg 17-39. The relevant equation is: h^ ~ .323D[—] 12 [- ] 13 Where: D is chemical diffusivity u∞ is free stream velocity v is kinematic viscosity By integration over the distance x = L, the average value of h_jHEM over the distance L can be determined: 1 1 3 For comparison assume that for the roller transport case, D = 5 x 10 ~ 6 cm^/sec (as before) , L = 1.0 cm, v = .0072 cm^/sec and a liquid temperature of 95 degrees Fahrenheit. Based on these corresponding assumptions h^HEM = -0022, 27 percent less than the value of .0030 achieved with the invention. In addition to the higher average value of he ^ the invention has many distinct additional advantages. Most apparent is the fact that a value of .0022 for would be extremely difficult to achieve for a number of reasons. For example, roller spacings of 1.0 cm would require very small rollers spaced very close together and many supporting parts. Also, the above equalizers for the roller transport apparatus assume that the rollers reduce the chemical boundary layer thickness to zero as the film contacts each successive roller. This is not the case. The film "hydroplanes" on each roller leaving some residual chemical boundary layer in place. This increases the mass transfer coefficient by a fixed amount over the entire film surface. In addition, roller transport tank processors require the film to move at high speeds creating difficult transport reliability problems. Also, reasonable development times require very large machines. As a practical matter, the same parameters cannot be assumed for a roller transport tank processor. More practically, L would be 4 cm or more, ϋ» would be in the range of 2.5-5.0 cm/sec and more likely 5.0 cm in the worst case situation. With these constraints hcjjEM would be .00048-84 percent less than the value of .0030 calculated for a parallel plate processor in accordance with the invention. Fig. 7 is a graph illustrating the results achieved with the invention incorporated into a chemical treating apparatus using hydroquinone as the treating fluid in comparison with a conventional roller transport processor. Curve A is a plot of boundary layer thickness vs. distance from the lead edge of a fluid path in a prior art roller transport processor. Curve B is a similar curve for a prototype processor incorporating the present invention. Curve B represents the boundary layer thickness with injection slits located at the far left and far right of the diagram and the evacuation slit located in the center. The difference in average boundary layer thickness (dashed lines A]_ and B^) is large and indicates the unexpected results achieved with the invention. Referring to Fig. 2 of the drawings, a parallel plate processor 28 is shown which incorporates the invention described in connection with Fig. 1. This processor comprises a pair of spaced parallel plates 30, 32 having a pair of juxtaposed injection slits 34, 36 and two pairs of juxtaposed evacuation slits 38, 40 and 42, 44. The plates may be supported by end walls (not shown) similar to the Fig. 1 assembly to define a channel 48 therebetween through which the film F is transported such as by rollers as described below. The solution circulation paths are illustrated in Fig. 2 by the arrows which are also schematically representative of system plumbing. It is to be understood that the processor depicted may include additional injection and evacuation slits by extending the length of the plates 30 and 32. Thus, the circulation pattern depicted schematically may be repeated by providing additional alternating solution injections and evacuations depending on the requirements of a particular application. Referring now to the circulation pattern, solution is supplied to injection ports 34 and 36 from mixing tanks 48, 50 respectively. Fluid will exit channel 48 via evacuation slits 42, 44 and 38, 40 as indicated by the arrows. A portion of the solution exiting via slits 38 and 42 may be recirculated by pumps 52, 54, respectively, to mixing tank 49 and the remainder circulated to the adjacent mixing tanks (not shown) in the series, as indicated by the arrows, if a need for replenishment exists, fresh solution may be supplied to tank 49 by a pump 56. The need for such replenishment may be sensed by sensors 60, 62 connected to the return inlet conduits to the mixing tank 49 and coupled to a control means 64 which will activate pump 56 when the need exists. Control means 64 can also be arranged to control pumps 52, 54. Slits 36, 40, 44 are similarly connected to mixing tank 50, pumps 66, 68 and 70 being provided to accomplish such recirculation and replenishment in the identical manner described in connection with tank 49. Also pumps 68, 70, 72 may be controlled by control means (not shown) and sensors (not shown) identical to control means 64 and sensors 60 and 62. For simplicity, two recirculation and replenishment systems have been shown. However, as will be obvious to those skilled in the art, the tanks 49, 50 may be replaced with a single tank connected to both injection slits 34, 36 and solution can be recirculated from evacuation slits 42, 44 and 38, 40 to such single tank. Alternatively fluid ducts and pumps with adequate capacity could be used without a specific tank. In operation of the processor shown in Fig. 2, solution will be circulated from tanks 49, 50 to injection slits 34, 36 to thereby create solution cushions under pressure on both sides of the film. From each silt, solution will flow right and left on both sides of the film as indicated by the arrows. At each evacuation slit, solution from the two adjacent injection ports will exit as indicated by the arrows. If the processor is a simple processor having only the ports shown in Fig. 2, the solution exiting slits 42, 44 and 38, 40 would only be that entering via slits 34, 36. Such a processor would be provided with a slit 76 in an end wall 78 for exiting of the film between a pair of squeegee and transport rollers 80, as shown in Fig. 3. Similar structure may be provided at the entrance to the processor to transport film into the processor. Similar to the processor shown in Fig. 1, solution entering the channel 48 will have maximum chemical or heat transfer adjacent the injection slits 34, 36. As it flows toward the evacuation slits, for example, slits 38 and 40, the boundary layer B will increase in thickness, as indicated in Fig. 2. As in the processor shown in Fig. 1, it is desirable to exit the solution when the boundary layer becomes so thick as to render the processing inefficient. Accordingly, length of channel 48 between adjacent slits is sized to exit the solution into an evacuation slit when a predetermined boundary layer thickness exists. As indicated above, the maximum thickness is such as to maintain an aqueous chemical mass transfer rate that exceeds the transfer rate within the film by a reasonable margin. Also, as discussed in connection with the Fig. 1 embodiment, the plate separation is made small to achieve high fluid velocities in the laminar flow region. It will be apparent to those skilled in the art that by providing appropriate valves and plumbing, different solutions may be successively supplied to the processors disclosed herein to sequentially subject the film to a series of treatments, e.g., developing, fixing, washing and drying. Alternately, a series of separate processors such as shown in Fig. 4 may be provided with each processor subjecting the film to a different treatment. Nip rollers 80 would be provided at the entrance and exit of each processor to transport the film along the treatment path. The exit rollers of wet solution processors would be squeegee rollers to remove excess solutions. If the system of Fig. 4 is used to process sheet film (e.g., X-ray film), the processor would be sized and spaced so that the distance between adjacent pairs of nip rollers is less than the length of the sheet. The invention has particular utility in processing sheet film because the increased processing efficiency enables use of smaller processing units to reduce machine size or to permit processing of small film sheets. Referring to Fig. 5 and 6 of the drawings, still another embodiment of the invention is disclosed for use in a submersed condition. This embodiment comprises a parallel plate processing unit 82 having a pair of parallel plates 84, 86 positioned and supported by side walls 88 to define a channel 90 for receiving a web F of light sensitive material such as photographic film. The plates 84, 86 are provided with first and second pairs of juxtaposed injection slits 92, 94 and 96, 98 disposed on opposite sides of a pair of juxtaposed evacuation slits 100, 102. The injection and evacuation slits are sized and spaced as described above to evacuate fluid from the channel 90 when the boundary layer of the treatment fluid becomes thick enough to render its use inefficient. The plates 84, 86 are attached to manifold plates 104, 106 respective, which in turn are attached to outer plates 108, 110. Manifold housings 112, 114 are attached to plates 108, 110 respectively and have chambers for receiving treating fluid under pressure via conduits 116, 118, respectively. The pressurized fluid in housings 112, 114 will flow to the injection ports 92, 94 and 96, 98 via openings in plates 104, 108 and plates 106, 110 and will be injected into channel 90 to establish a laminar flow of fluid on opposite sides of the film in one direction to the evacuation ports and in the opposite direction to the open ends of channel 90. Fluid evacuated from the channel 90 by evacuation ports 100, 102 will flow out the sides of the unit via openings in plates 104, 106. It is to be understood that, as described in connection with Fig. 2, additional injection and evacuation ports may be provided depending on the requirements of a particular treatment process. Fig. 6 depicts the use of processors of the type shown in Fig. 5 or Fig. 1 to process photographic film. More specifically, an elongated housing 126 is provided with a plurality of treatment chambers 128, 130, 132, 134 for film development, fixing, washing and drying, respectively, as indicated in Fig. 6. A processing unit 82 is suitably supported in each chamber with the units 82 in chambers 128, 130, 132 submersed in the liquid processing solutions, as indicated. Each processing unit may be provided with a circulation system, such as that shown in connection with the unit 82 in chamber 128. In its most simple form the system would include a pump 136 having its inlet connected to the chamber 128 and its outlet connected to the manifold housings 112, 114 whereby fluid will be continuously circulated from the chamber to the injection ports 92, 94 and 96, 98. Fluid discharged from the evacuation ports 100, 102 and the ends of the channel 96 will mix with the fluid in chamber 128. As will be apparent to those skilled in the art, the mixing action can be augmented by providing a mixing impeller (not shown) in chamber 128. Also, suitable replenishment means (not shown) may be provided to periodically supply fresh fluid to the system. The film transport means comprises entrance and exit chutes 140, 142 for guiding the film into the first chamber 128 and exiting the film from the last chamber 134. Identical chutes 144 and pairs of nip rollers 146, 148 (one pair between adjacent chambers) transport the film from chamber to chamber. At each processing unit, the associated chutes will guide the film into and out of the channel 90 and nip rollers. Embodiment of Figs 9-11 Referring to Figs. 9 and 10 of the drawings the invention is embodied in a film or paper dryer 160 comprising a pair of juxtaposed air bearings 162, 164. The bearings 162, 164 comprises rectangular housings having sidewalls, end walls and cover plates (not shown) attached to spaced parallel plates 166, 168 respectively. The plates are fixed together in spaced relationship with spacers 170 interposed to provide the desired spacing described below. The plates 166, 168 are provided with central elongated openings or slits 172, 174, for injecting air under pressure into the space between the plates from the interior of the bearing housings, respectively. A plenum 176 (one is shown in Fig. 10) connected to a source of air under pressure is attached to each housing. As shown in Fig 1 the bearings 162, 164 are spaced to define a channel 178 there between for a web W which may comprise light sensitive material. The web W may be transported to the channel 178 by a pair of nip rollers 30 which may comprise the exit squeegee rollers of a wash section of a film processor. Preferably, the air bearings are skewed 10 to 15 degrees from the longitudal axis of the rollers to reduce aeroelastic flutter in the leading and trailing portions of the web. In operation of the dryer air under pressure will be injected from the plenums 176 into the bearings 162, 164 and through the slits 172, 174 into the channel 178 to establish regions of air under pressure on opposite sides of the film. As a result a laminar flow of air will occur in opposite directions from each slit relative to the film path. The air streams will exit the channel 178 at the opposite sides of the plates 166, 168. The thickness and length of channel 178, width of slits 172, 174, air pressure with the bearings 162, 164 are parameters which are preferably selected to control the boundary layer thickness and to minimize the distance over which the boundary is permitted to develop. Also the system parameters are selected to establish reasonably high fluid velocities in the laminar flow region to minimize the rate at which the boundary layer is allowed to grow. The result is to establish a heat transfer rate in the fluid that exceeds the heat transfer rate within the film or paper. A small plate separation contributes to the achievement of high fluid velocities with laminar flow. These concepts are more fully described above. In accordance with the teachings presented above, the thickness of channel 178 is preferably .06- .09 inches. The length of the fluid path along the film direction is in the range of .3 to .8 inches depending on the total amount and transfer rate of heat needed. The slots 172, 174 in the plates 166, 168 are preferably .015 inches wide. Air within the bearing is typically at 3.4 inches of water pressure and a temperature of 90 to 130 degrees Fahrenheit depending on the drying speed needed and particular film characteristics such as amount of gel, etc. The pressure drop in the slots 172, 174 is approximately 50 percent of the available pressure. Pressure at the film plane is dependant on the flow rate of air through the slot, the higher the flow rate the greater the pressure drop. As discussed above, if the film moves from a center position towards either plate a pressure differential is established above and below the film which restores it to a center position. With the film thus centered in the channel 178 the boundary layer thickness reduction discussed above, and thereby improved heat and water vapor flow, is provided by the high speed flow of air from the slits over the film and out the sides of the bearings. Control of boundary layer thickness is a function of the channel size, length of the channel and the pressure of the air injected through the slits. Heat flow to the film is a function of air temperature and also boundary layer thickness. Water vapor removal is primarily a function of boundary layer thickness and the rate heat can be supplied to vaporize water in the gel coat of the film or paper. Fig. 11 depicts curves plotted from actual measured heat transfer coefficient values for a dryer in accordance with the invention (curve A) having 4 cm wide bearing plates 166, 168 and a commercially available M6B X-OMAT dryer (curve B) manufactured by Eastman Kodak Company. As can be seen from Fig. 11 the average value of the M6B dryer is approximately 7 BTU per hour per square foot per degree Fahrenheit whereas the dryer in accordance with the invention has an average value of approximately 38 BTU per hour per square foot per degree Fahrenheit. This dramatic increase in efficiency indicates the superior performance of apparatus in accordance with the invention. Most significant is the fact that this improvement in drying efficiency was achieved with a much smaller and lower cost dryer. It will be apparent that different web materials may require longer or smaller bearing widths (flow path lengths) or even multiple bearings. It will be apparent that the embodiment of Figs. 9-11 achieves higher heat transfer coefficiates which means faster drying, smaller simpler dryers, lower drying temperatures and less energy consumption. The air suspension of the film or paper in the dryer reduces the chance of film scratches/artifacts in the dryer. Less drying energy means less heat lost to the environment, less need to cool the processing chemicals and no need for special power connections to the processor. Also the simplicity and small size of the . dryer requires fewer parts and greatly reduces the cost of the dryer. Rmbodiments of Figs. 12-20 In the apparatus disclosed in Figs. 1-8 fluid is injected into and evacuated from the channel by means of juxtaposed injection slits and evacuated by means of juxtaposed evacuation slits. The slits extend transversely of the film axis in substantially perpendicular relationship therewith. Each juxtaposed path of injection slits is positioned between two pair of juxtaposed evacuation slits to cause fluid to flow in opposite directions from each injection site to adjacent evacuation sites. While the apparatus disclosed in Figs 1-8 achieves mass and heat transfer that is clearly superior than prior art apparatus while supporting a web out of contact with channel surfaces, it has been found that some instability of the web can occur which results in web vibrations particularly when such apparatus is used to dry web material with air. Such conditions do not effect the performance of the disclosed apparatus, but provide opportunities to further enhance the results achieved. Because of the alternating arrangement of injection and evacuation sites, there are also alternating regions of high and low pressure in the film channel. The pressure of the fluid on each side of the web is maximum at the injection sites and minimum at the evacuation sites. As a result, the web has maximum support at the injection sites and minimum support at the evacuation sites. If the injection and evacuation sites extend perpendicular to the film axis, then transversely extending low pressure regions exist which provide minimal support to the web and render it subject to displacement by gravity. Because of the alternating arrangement of these high and low pressure regions, the web can even vibrate or oscillate even though it remains out of contact with the surfaces of the channel. The condition described is most apparent when transporting the leading or trailing end of a web through the channel. Because the end is free, it can act as a cantilever beam and is even more affected by the high and low pressure zones. The pressure forces can even produce web end lift particularly when the treating fluid is air. These effects are more pronounced when drying large sheets of material such as photographic film. In accordance with this embodiment the condition described above is minimized by arranging the injection and evacuation slits at an angle relative to the longitudinal axis of the web. This causes the high pressure and low pressure regions to extend angularly across the film. With this arrangement each injection opening produces a fluid stream having one flow component angled relative to the longitudinal axis of the web in the direction of web travel and a second flow component angled relative to the longitudinal axis opposite to the direction of web travel. The components in the direction of web travel minimize lift of the web by the treating fluid and have a stabilizing effect. Also, the pressure of the fluid emitted from the angled openings tends to produce pressure corrugations in the web extending angularly to the web longitudinal axis. Such corrugations tend to reinforce the web and make it more resistant to bending and less subject to vibration. Referring to Figs. 12 and 13 of the drawings, there is shown a pair of spaced plates 210, 212 adapted to be clamped together and separated by spacers 213 to define a channel 214 (Fig. 15) therebetween for receiving a web W, eg. photographic film. The plates 210, 212 each have a plurality of elongated spaced fluid injection openings or slits 216 and a plurality of elongated spaced fluid evacuation openings or slits 218. When the plates are clamped together, the openings 216 in plates 210 and 212 will be aligned and in juxtaposed relationship. Similarly, openings 218 in plates 210 and 212 will be in aligned juxtaposed relationship. The openings 216 and 218 alternate so that each pair of juxtaposed injection openings is between two pairs of juxtaposed evacuation openings. As will be discussed in more detail below, all of the openings 216 and 218 are positioned in parallel relationship and define an axis having an angular relationship with the longitudinal axis of the film. This angular relationship of the openings with the longitudinal axis of the film is most clearly apparent from Fig. 17. While an angle of 45 degrees is preferred enhanced positional stability can be achieved with angles as small as 15 degrees and as large as 90 degrees. A plurality of elongated hollow spacer members 222 are fixed to the plates 210 and 212 with the hollow interiors of the members in communication with the openings 216. A pair of plates 224, 226 are positioned over the members 222 on the sides opposite from the plates 210, 212 respectively. Slots 228 in the plates 224, 226 communicate with interiors of members 222 to supply fluid to the slots 216 via the interiors of members 222. A pair of housings 230, 232 are fixed to the plates 224, 226, respectively, to provide manifold chambers 234 and 236 for supplying air to the openings 228. The ends of the chambers 234, 236 may be sealed by end plates 238, one of which is depicted in Fig. 12. Each housing 230, 232 is provided with an air inlet opening 240. Blowers 242, 244 (Fig. 12) supply air under pressure to each inlet. It will be obvious that each of the plates 224, 226 may be formed integrally with its associated housing and thus comprises a wall of such housing to thus define a housing means having chambers for supplying fluid to the channel 214. To complete the assembly bolts 246 which extend through holes in the plates and through the spacers 213 (Fig. 12), clamp the plates 210, 212, 224, 226 together. When so assembled, the channel 214 between plates 210, 212 will have a length equal to the thickness of spacers 213. In operation of the dryer, fluid under pressure (in this case, air) will be supplied to the chambers 234, 236 by blowers 242, 244 to pressurize the chambers. From chambers 234, 236, air will flow through slits 228 and the interior of members 222 to slits 216. Air will be injected through slits 216 into channel 214 on opposite sides of the film to create regions of air under pressure on opposite sides of the film. Air will flow from the slits 216 to the adjacent evacuation slits 218 as indicated by the arrows in Fig. 17 and be subsequently evacuated into the space between plates 210, 224 and between plates 212, 223. The slits 216 are preferably sized and spaced from the slits 218 by a distance such that the air is evacuated when the boundary layer reaches a thickness rendering the heat transfer between the air and film inefficient. More specifically, the heat transfer process is enhanced by minimizing the length of the flow path from an injection slit to an evacuation slit to minimize the distance over which the boundary layer is permitted to develop and by minimizing the rate at which the boundary layer is allowed to grow, the latter is achieved by using reasonably high fluid velocities in the laminar flow region. This concept is disclosed in more detail above. Referring now to Fig. 19 which is a side view of the assembled dryer, the web W is transported through the processor by two pairs of nip rollers 250 and 252 adjacent the entrance and exit of the channel 214 respectively. Such rollers may be driven by motors 254, 256 as indicated. When drying webs in sheet form, the rollers would be spaced by a distance less than the length of the sheet so that the sheet is gripped by the exit rollers before it leaves the entrance rollers. Considering now the angular relationship of the slits 216, 218 with the longitudinal axis of the web, it will be apparent from Fig. 17 that the air flowing from each slit 216 will have two components, one traveling with the web at a 45 degree angle to the longitudinal axis of the web and another traveling in the opposite direction to the first at a 45 degree angle to such axis. This increases film stability by minimizing the lift caused by the flow of air traveling against the direction of film travel. Also, as discussed above, the alternating high and low pressure regions extend angularly across the film and tend to produce a corrugated force pattern as shown in Fig. 18. Because this force pattern is angularly oriented relative to the film it tends to deform the film into a shape that has a higher bending moment that makes it more difficult to deform the film. These conditions coupled with the inherent stability produced by having fluid streams on opposite side of the film results in greater strength, less vibration and greater resistance to bending. The apparatus thus effectively adds to the basic stability achieved by having laminar air streams on opposite sides of a web as disclosed above by providing an singularly oriented force pattern across the web. Another embodiment is depicted schematically in Fig. 20. In this embodiment a dryer 260 is provided with a channel 262 having a plurality of injection slits 264 and a plurality of evacuation slits 266 which are shown exaggerated in size. In this embodiment the injection and evacuation slits alternate on each side of the channel as in the previous embodiment. However, in the case an evacuation slit 266 is always in juxtaposed relationship with an injection slit. This produces a differential force on the film at each site as indicated by the vertical arrows which indicate the force direction. As a result, the film is forced into a physically corrugated configuration as shown. If the slits are angularly oriented relative to the film axis, the physical corrugations will substantially increase the bending resistance of the film. It will be apparent that the appartus disclosed in Figs. 12-20 thus greatly improves the stability of a moving web during transport through a fluid treatment channel and have particular utility in a dryer. The fluid streams on opposite sides of the web tend to support and stabilize the web. The angled orientation of the fluid injection and evacuation openings further stabilize the web by minimizing web lift and producing a corrugated force pattern on the web to increase the strength of the web and reduce web vibration. Embodiments of Figs 21-22 In accordance with these embodiments, a web treatment apparatus such as a film or paper processor comprises a means defining a channel through which the web is transported. Treatment fluid is injected into the channel on opposite sides of the web at spaced injection sites and evacuated from the channel on opposite sides of the material at spaced evacuation sites. The injection sites and evacuation sites alternate so that injected fluid is evacuated from adjacent evacuation sites. The streams of evacuated fluid are combined such that streams varying in flow path length and chemical depletion are sequentially mixed together prior to reinjection into the channels. Such mixing results in more uniform composition of the fluid reinjected. Referring to Fig. 21, there is shown a portion of a parallel plate film processor 310 comprising a pair of spaced parallel plates 312, 314 defining an elongated fluid processing channel 316 adapted to receive a web (in continuous or sheet form) of photographic film. The plates are supported by a pair of end walls 317, 318 having slits 320, 322 respectively for the entrance and exit of the film. The film F is transported through the channel in the direction indicated by transport means comprising two pairs of nip rollers 324, 326. One or both pairs of the nip rollers may be motor driven depending on whether the film F is in sheet or web form. If sheet film is being processed, the length of channel 316 will be less than the sheet length whereby rollers 324 will grasp the sheet before it leaves rollers 326. Also, if a liquid solution is applied to the film, the exit rollers 324 may comprise squeegee rollers to remove excess solution. The plates 312, 314 are provided with a plurality of pairs of spaced juxtaposed injection slits 330, 332, 334 and a plurality of pairs of spaced juxtaposed evacuation slits 336, 338, 340, 342, which define injection and evacuation sites. The injection and evacuation slits extend transversely of the channel and have a length at least equal to the width of the film. The slits are placed in an alternating pattern so that each pair of juxtaposed injection slits is between two spaced pairs of juxtaposed evacuation slits with equal spacing between adjacent slits along the film path. In operation, fluid injected into the channel 316 under pressure will form cushions of fluid under pressure on opposite sides of the film. This cushion will support the film and cause a laminar flow of fluid on each side of the film to the adjacent evacuation slits where it will be evacuated to the exterior of the processor. As disclosed in connection with the embodiments of Figs. 1-8, the spacing between adjacent slits is selected to cause evacuation of the flowing fluid when its boundary layer becomes thick enough to render the treatment of the film inefficient. Such conditions are more fully described above and further description here is deemed unnecessary. The recirculation and replenishment system is illustrated by lines and arrows in the drawing for clarity. Arrangements of suitable piping to accomplish the flow and mixing indicated is within the capability of one skilled in the arts of fluid mechanics and plumbing and further disclosure is deemed unnecessary. Also, the fluid circulation and mixing system on the upper and lower sides of the film are identical and only the upper system will be described in detail. Referring to the drawing, the recirculation system includes a mixing means comprising a pair of spaced parallel plates 350 and 352 defining an elongated mixing chamber 354. The plates 350 and 352 may be supported by end plates 356 and 358. Alternatively, plates 350 and 352 and one of the end plates may be formed as an integral molded housing and the other end plate attached to such structure. The end plate 358 may be provided with elongated funnel-like outlet fitting 360 which is coupled to a recirculation pump 362. The plate 352 is provided with a plurality of inlet ports 364, 366, 368, 370 connected with the evacuation ports 336, 338, 340, 342 respectively by suitable plumbing as indicated schematically. The pump 362 is connected by suitable plu bing and/or manifolds to the injection ports 330, 332, 334 and 336 as indicated schematically. At the outlet of the pump, a sensor 372 may be provided to determine the condition of the fluid being recirculated. A control means 374 responsive to the output of the sensor may be arranged to open a replenishment valve 376 when the fluid condition in such as to require mixture with fresh solution. Alternatively, the fluid may be discarded or treated to remove undesirable byproducts, such as to minimize environmental discharges. In operation of the mixing system, it will be noted that a portion of the fluid injected at port 334 will be evacuated at port 342, the port most remote from the outlet 360 of the mixing chamber. Since this fluid stream treated the leading end of the film, it is most depleted in chemistry. The injection into the mixing chamber at the end remote from the outlet gives this stream the entire length of the mixing chamber to mix with less depleted fluid streams. The other portion of the fluid injected at port 334 and a portion of the stream injected at port 332 will be evacuated through port 340 and enter the mixing chamber at port 368, the second most remote port from the chamber outlet. These two streams will mix together in ports 340 and 368 prior to entering the chamber and the combined stream then will mix with the fluid evacuated at port 342. Thus, in the region of the mixing chamber adjacent port 368, three streams will essentially have been mixed, all of which originally differed in chemical depletion. These streams will also differ in time phasing with respect to injection into and evacuation from the processor resulting from the different flow path lengths from the pump to the injection ports. This difference in time phasing will also augment the mixing action. The sequential mixing action will continue as the mixed stream flows toward the outlet 360. At port 366, a mixed stream containing portions of the fluid streams injected at ports 332 and 330 will enter the chamber and mix with fluid stream comprised of fluids from ports 368 and 370. This further combined mixed fluid stream will mix with the remainder of the stream injected at port 330 in the region of port 364. Thus, the fluid discharged at the outlet of the chamber will be thoroughly mixed and substantially uniform in composition. It will also be apparent that mixing occurs in all parts of the system including the pump 362 the inlet ports to the mixing chamber, and the injection and evacuation ports. The apparatus thus comprises a closed loop processing system in which essentially all of the fluids are mixed and recirculated very frequently. Most importantly all fluids pass through a single region (the pump) which enhances the mixing before the fluid is redistributed. The high agitation within the pump insures complete mixing. The advantages of the mixing process will now be apparent. The most chemically depleted fluid streams are sequentially injected into the mixing chamber at points progressively spaced in order of depletion with the most depleted streams injected at the end most remote from the outlet and the least depleted stream injected closest to the outlet. In addition, adjacent streams are combined in the evacuation ports prior to injection into the mixing chamber to enhance the mixing process. The mixing is further enhanced by the different lead times of the fluid streams. For example, changes in the chemical concentration of fluids in the short flow paths having varying chemical concentrations are rapidly mixed with fluids in the medium and long flow paths. Similarly, the addition of chemical replenishment in the shorter path (exit of pump 362) is rapidly disseminated to the other longer paths. These features result in a highly ordered sequential mixing process with outstanding solution uniformity. Also, the mixing occurs without the use of moving parts. An apparatus incorporating the concepts disclosed herein is capable of achieving total solution turnover every 5-10 seconds. By comparison, a typical roller transport deep tank processor has stagnant regions which contain fluid that is turned over or recirculated only every 5-20 minutes. This comparison indicates the superior performance that is achieved with the closed loop mixing process in accordance with the invention. Referring to Fig. 22 of the drawings there is shown another embodiment of a closed loop mixing system. This embodiment would also include a pair of parallel plates similar to the Fig. 21 embodiment and would also have spaced slits in the plates to define a plurality of injection sites 310 and a plurality of evacuation sites 312, the sites alternating as in the case of the Fig. 21 embodiment so that an injection site is located between adjacent evacuation sites. The spacing between the sites is selected to cause evacuation of the flowing fluid when its boundary layer becomes thick enough to render the treatment of the film inefficient. The plumbing for the system shown in Fig. 22 is indicated schematically to clarify the operation of the invention. It will be obvious, however, that arrangements of suitable manifolds and plumbing to accomplish the circulation indicated are within the capabilities of one skilled in the arts of fluid mechanics and plumbing. It is also to be understood that as in the case of the Fig. 21 embodiment, the systems on each side of the film are identical with juxtaposed injection and evacuation slits. According only the system on the upper side of the film is shown and described. Referring now to the circulation system the solid lines represent the flow paths of fluid from the pump 314 to the injection sites 310 and the dashed lines represent the flow paths of fluid from the evacuation sites to the inlet of the pump. In the injection system it will be noted that the output of the pump is uniformly and sequentially divided at node or branch points 316 and that the evacuated fluid is uniformly and sequentially combined at node or branch points 318. In the evacuation system all fluids are progressively mixed after contacting the film or paper. Also, all fluids pass through a single region (the pump) before being circulated. The high agitation within the pump assures that the fluid streams are completely mixed and the branch points or nodes provide sequential mixing of streams varying in chemical depletion and time phasing prior to entering the pump. Embodiments of Figs, 23-33 In U.S. Patent No. 4,994,840, issued February 19, 1991 and entitled, Apparatus for Processing Photosensitive Material, there is disclosed a processor for photographic film or paper comprising a levitation chamber submersed in a tank. The film or paper is transported through the chamber. The static pressure of the fluid in the tank is used to circulate processing solution through the chamber. The film or paper web is fed into the end of a processing channel. Processing fluid is introduced at the opposite ends of the channel and discharged at the center of the channel. In accordance with this embodiment of the present invention, a plurality of hydrostatic bearings are supported in spaced relationship in a processing chamber filled with processing solution. Processing solution is circulated by a pump from the chamber to a manifold and to the bearings. The solution is discharged by the bearings into contact with the film to effectively suspend the film out of contact with bearing surfaces. Referring to Fig. 23 of the drawings, there is shown a film processor 410 comprising a container or tank 412 defining a chamber 413 for processing solution or wash water and a housing or tank 416 for a pump 418. Interposed between the tanks 414 and 416 are a plurality of stacked walls or plates 422, 424, 426, 428, 430 and 432 (Fig. 26) which define the solution distribution channels for the processor. The plate 422 may comprise one side wall of tank 412. The plates 424-432 are suitably attached to walls 422 of the container tank 412, as shown in Figs. 23 and 27. The tank 16 may be attached to end plate 432, as shown. A plurality of elongated hydrostatic bearings 438 are positioned in chamber 414 in parallel spaced relationship with the configuration shown in Fig. 26G which is a view of the end wall 422 with the bearings mounted on it, to produce a curved film path as described below. The ends of the bearings 438 are fixed to the plate 422. As described in more detail below, the bearings 438 are immersed in processing solution in tank 412 and have internal cavities which are supplied with processing solution by pump 418 through the manifold defined by plates 422, 424, 426, 428, 430 and 432. Plate or wall 432 (Fig. 26F) comprises a pump face or pump inlet and outlet plate and has an inlet opening 440 communicating with an inlet or suction chamber 442 (Figs. 27 and 28) of the tank 416, and an outlet opening 444 for discharging solution from the high pressure or outlet chamber 446 of the tank 416. The pump impeller 448 is positioned in the outlet chamber 446 and is rotatable by pump shaft 450 to circulate solution from chamber 442 into chamber 446 through openings 449. Plate 430 (Fig. 26E) , which comprises a solution return plate has an elongated rectangular opening 450 for circulating solution returned from the chamber 413 to the pump chamber 442 and has an opening 452 located to align with opening 444 of plate 432. Plate 428 (Fig. 26D) serves to provide positive to negative pressure insulation and is provided with openings 454, 456 and 458 located to communicate with opening 450 in plate 430. The plate 428 is also provided with an opening 460 located to align with opening 452 of plate 430. Plate 426 (Fig. 26C) is provided with a horseshoe shaped opening 462 which communicates with the opening 460 in plate 428 and is provided with openings 463, 464 and 466, which are aligned with openings 454, 456 and 458, respectively, of plate 428. Plate 424 (Fig. 26B) comprises an allocation manifold having solution return openings 468, 470 and 472 aligned with openings 463, 464 and 466 of plate 426. The plate 424 also has a plurality of equally- sized openings 474 (two for each bearing) arranged * in a horseshoe pattern in alignment with the openings in the ends of the bearings 438 to distribute solution to the ends of the bearings from the opening 462 in plate 426. Wall 422 (Fig. 26A) is almost identical to plate 424 and is provided with openings 476, 478 and 480 aligned with openings 468, 470 and 472, respectively, of plate 424. The plate 422 is also provided with a plurality of openings 482 (two for each bearing) aligned with but slightly smaller in size than openings 474 of plate 424 to gradually reduce the cross-section of fluid flow into the bearings 438. The bearings 438 are attached to the plate or wall 422 such as by welding of the bearing ends to the surfaces of wall 422 around the openings 482 whereby the openings 482 communicate with only the interiors of the bearings. In operation of the fluid distribution system pump 418 will pump fluid from chamber 446 through openings 444, 452 and 460 of plates 432, 430 and 428, respectively, into the manifold opening 462 of plate 426. From opening 462 of plate 426, solution will be distributed through openings 474 and 482 of plates 424 and wall 422, respectively, to the interior of the hydrostatic bearings 438. Fluid will be discharged from the bearings 438, as described in detail below, into tank 412. The discharged solution will be recirculated from tank 412 via openings 476, 478 and 480 in wall 422, openings 468, 470 and 472 in plate 424, openings 463, 464, and 466 in plate 426, openings 454, 456 and 458 in plate 428, opening 450 in plate 430 and opening 440 in wall 432 to the pump suction chamber 442. Referring now to the unique features of the hydrostatic bearings 438, and specifically to Figs. 23, 29, 30 and 31 of the drawings, each bearing comprises a pair of identical elongated juxtaposed assemblies 490a and 490b (Figs. 30 and 31) positioned in spaced relationship to permit passage of a web W of light sensitive material in continuous or sheet form therebetween. Each assembly defines an elongated channel shaped housing 491 having a rectangular cross section which receives solution under pressure from an opening 482 in plate 422. The channels 491a and 491b are fixed to flanges 492a and 492b, respectively, which are each provided with a plurality of spaced openings 494a and 494b, respectively, for discharging fluid from SUBSTITUTESHEET the interior of the channels to the area external of said flanges. A second pair of flanges 496a and 496b are fixed to flanges 492a and 492b, respectively, and are each provided with a plurality of spaced rectangular openings 498a and 498b, respectively, which receive solution from openings 494a and 494b, respectively, to establish regions of pressurized solution on both sides of the sheet W. Each pair of juxtaposed assemblies are positioned in closely-spaced relationship with a small gap between the faces of flanges 496a and 496b for the passage of web W therebetween, as shown most clearly in Fig. 30. For a web having a thickness of .007 inches, the spacing is preferably .050 inches. This spacing is achieved by positioning spacers 499 (Fig. 31) between the two assemblies at both ends thereof. The assembled bearings are then attached at one end to the plate 422 with the open ends of channels 490a and 490b aligned with a pair of openings 482. The other ends of the channels 490a and 490b are fixed together and sealed by an end cap 501 (Fig. 23) to restrict discharge of solution to openings 494. The fixed mounting of one end of the bearing 438 to the plate 420 and the attachment of the end cap 501 provides a rigid bearing structure. The bearings are preferably sized to define fluid path lengths within the bearing such as to evacuate solution into the tank when the fluid boundary layer reaches a predetermined thickness. Such criteria is disclosed above in connection with the embodiments of Figs. 1-8. The plumbing system is preferably structured to produce a fluid pressure of 2 - 6 inches of water in each of the rectangular openings 498a and 498b. With this arrangement, a liquid cushion will exist on each side of the web within each bearing to provide for smooth transport of the web without contact with the bearing surfaces. In the relatively straight portions of the web path, the juxtaposed face surfaces of the flanges 496a and 496b are flat, as shown in Fig. 30 and 31 and in detail in Fig. 32A. However, in the curved portions of the web path, the juxtaposed face surfaces of the flanges 496a and 496b are curved to define a curved web path therebetween. In these path sections, one flange 496 will be provided with a concave surface 500, as shown in Fig. 32C and the opposing flange 496 will be provided with a complemental convex surface 502, as shown in Fig. 32B. The curved web path thus established will be apparent from viewing the lower four bearings in Fig. 29. A bridging means is provided between adjacent bearings 438 to insure that the leading edge of the web leaving one bearing feeds correctly into the next bearing in the web path. Referring to Fig. 29 of the drawing, an arcuate bridging member 504 is positioned between adjacent bearings. Flanges 506 and 508 of the member 504 are fixed to the flanges 492 of the adjacent bearings 438 to position the surface 510 of member 504 into contiguous relationship with the surfaces of the flanges 496b. The surface 510 thus defines a bridge between the gaps of adjacent bearings. In Fig. 29, the bearings 438 are depicted in a curved film path. It will be apparent, however, that various path configurations may be employed and the disclosed configuration is exemplary only. If the web being processed is in sheet form such as, for example, X-ray sheet film, the film path defined by the hydrostatic bearings 438 will be shorter than the length of the film sheets so that roller means at the entrance and exit to the path can transport the sheets into and out of the path without losing the sheet. In such a sheet film processor, a pair of rollers 520, as shown in Fig. 23., will be positioned at the entrance and exit of the tank chamber. If a series of processing chambers are provided, a pair of rollers 520 may be provided between adjacent tanks, as shown in Fig. 25. In this case, film guides 522 would be provided to facilitate transport between adjacent chambers. If the material being processed is a continuous web, such as spliced together lengths of 35 mm film, a roller means, such as rollers 520, may be provided only at the entrance to the web path, such rollers being sufficient to transport the film through the bearings supported by the liquid cushions. In this case, the rollers 520 between adjacent chambers are not necessary and the rollers 520 at the entrance to the first chamber can be used to transport the web through the entire system. Figs. 23 and 29 of the drawings show an arrangement of hydrostatic bearings for a single chamber processor. In this case, the bearings 438 would be arranged in a simple horse shoe configuration. However, if multiple chambers are provided, the bearings would preferably be arranged in the festooned configuration shown in Fig. 33 so that the web or sheet leaves each chamber along a smoothly curved film path. In the case of both sheet and continuous webs, it may be desirable to have rollers between chambers of multiple chamber process to provide a squeegee effect for removing liquid from the material before it enters the next chamber. The advantages of the disclosed processor will now be apparent. The fluid cushions established in the rectangular openings and adjacent regions effectively support the web being processing and permit it to be transported through the processing solution. Also, the system is constantly subjecting the web to recirculated fluid discharged from the bearings to reduce fluid stagnation. Thus, the bearings not only support the web, but render the treatment process more efficient. With respect to each bearing, fluid is injected from the center region of the bearing and discharged at the sides. This arrangement provides discharging fluid streams on both sides of the web at both the entrance and exit of the bearing and avoids lifting of the web into engagement with the bearing surfaces.

Claims: Claims 1. In apparatus for subjecting a web to treatment fluid, the improvement comprising: means defining a fluid treatment channel for receiving the web, said means defining in said channel an elongated injection opening for injecting fluid into the channel and an elongated evacuation opening, said openings extending transversely of said channel; means for supplying treatment fluid under pressure to said injection opening to inject treatment into said channel and establish a high velocity laminar fluid flow from said injection opening to said evacuation opening, said evacuation opening being spaced from said injection opening by a predetermined distance to effect evacuation of the fluid when the boundary layer of the fluid reaches a predetermined thickness to maintain an energy transfer rate in the fluid that exceeds the energy transfer rate within the web. 2. Apparatus as claimed in claim 1 the improvement further includes a second elongated evacuation opening for evacuating fluid from said channel, said injection opening being positioned between said evacuation openings in equally spaced relationship therewith whereby fluid flows from said injection opening to both of said evacuation openings. 3. In apparatus for subjecting a web to treatment fluid, the improvement comprising: means defining a thin fluid treatment channel for receiving the web and having elongated aligned injection openings on opposite sides of the web and elongated aligned evacuation openings on opposite sides of the web in spaced relationship with the injection openings; means for transporting the web through said channel; means for supplying treatment fluid under pressure to said injection openings to inject treatment fluid under pressure into said channel on opposite sides of the web to establish cushions of treatment fluid on opposite sides of the web within said channel to support the web and to establish a high velocity laminar fluid flow from said injection openings to said evacuation openings, said evacuation openings being spaced from said injection openings by a predetermined distance to effect discharge of fluid from said channel when the fluid boundary layer reaches a predetermined thickness to maintain a mass transfer rate in the fluid which exceeds the mass transfer rate in the web. 4. Apparatus as claimed in Claim 3 wherein said evacuation openings comprises the ends of said channel. 5. Apparatus as claimed in Claim 3 wherein said evacuation openings comprises spaced juxtaposed openings in said channel on opposite sides of the material. 6. Apparatus as claimed in Claims 4 or 5 wherein said injection openings comprises juxtaposed openings in said channel defining means on opposite sides of the material. 7. In apparatus for subjecting a web to treatment fluid, the improvement comprising: means defining a thin fluid treatment channel for receiving the web and having at least one pair of elongated juxtaposed injection openings for injecting fluid into said channel on opposite sides of the web and at least two pairs of elongated juxtaposed evacuation openings upstream and downstream of said injection openings respectively for evacuating fluid from said channel; and means for supplying treatment fluid under pressure to said injection openings to establish a fluid cushion under pressure on opposite sides of the web for supporting the web and for establishing a high velocity flow of fluid from said injection openings to said evacuation openings, the spacing between said pairs of injection openings and said pairs of evacuation openings being such as to evacuate fluid from said channel when the fluid boundary layer reaches a predetermined thickness to maintain a mass transfer rate in the fluid which exceeds the mass transport rate in the web. 8. Apparatus as claimed in Claim 7 wherein a plurality of pairs of juxtaposed injection openings and a plurality of pairs of juxtaposed evacuation openings are provided in a repeating alternating pattern of juxtaposed injection openings and juxtaposed evacuation openings. 9. Apparatus as claimed in Claim 8 wherein each pair of juxtaposed evacuation openings evacuates fluid from the adjacent juxtaposed pair of injection openings respectively. 10. Apparatus as claimed in Claim 9 further comprising means for recirculating fluid from said evacuation openings back to said injection openings. 12. Apparatus as claimed in Claim 9 further comprising means for at least partially replenishing fluid circulated back to said injection openings. 13. In a film processor for subjecting a light sensitive web to treatment fluid, the improvement comprising: means defining a thin fluid treatment channel; means for transporting the web through said channel; means for evacuating treatment fluid from said channel on opposite sides of the web at a first location; and means for injecting treatment fluid into said channel on opposite sides of the web at a second location spaced from said first location to establish a cushion of fluid on opposite sides of the web and a high velocity laminar flow of fluid to said evacuation means, said first location being spaced from said second location by a predetermined distance whereby the fluid is evacuated from the channel when the boundary layer reaches a predetermined thickness to maintain a mass transfer rate in the fluid which exceeds the mass transfer rate in the web. 14. In a film processor for subjecting a light sensitive web to treatment fluid, the improvement comprising: means defining a thin elongated fluid treatment channel for receiving the web; means for evacuating treatment fluid from said channel at a first location; and means for injecting treatment fluid into said channel at a second location spaced from said first location to establish a high velocity laminar flow of treatment fluid along said web from said second location to said first location; the spacing of said first and second locations, the thickness of said channel, and the fluid velocity having predetermined values such as to maintain an energy transfer rate in the fluid in said channel which exceeds the energy transfer rate in the web. 15. A film processor as claimed in claim 14 or 15 wherever the fluid in said laminar flow has an average mass transfer rate in the range of .010 cm/sec to .001 cm/sec. 16. In apparatus for drying a web, the improvement comprising: a pair of spaced parallel members having flat surfaces defining a channel there between of predetermined length for movement of the web there between; juxtaposed elongated openings in said surfaces respectively; means for supplying air under pressure to said openings to inject air into said channel on opposite sides of the web, establish cushions of air on opposite sides of the web, and flow of air in opposite directions from said openings over the surface of the web with a predetermined velocity, said channel having a length and thickness and said velocity having a magnitude such as to minimize the thermal boundary layer of the air flow and to maintain a heat transfer rate in the air in said channel which exceeds the heat transfer rate in the web. 17. Apparatus as claimed in Claim 16 wherein said members comprise flat plates and said openings comprise elongated slits in said plates respectively. 18. Apparatus as claimed in claim 17 wherein said means for supplying air to said slits comprising elongated housings attached to said plates respectively each of said housing defining a chamber for air under pressure. 19. Apparatus as claimed in Claim 18 further including a plenum attached to each of said housings. 20. In apparatus for subjecting a web to treatment fluid,the improvement comprising: means defining a fluid treatment channel for receiving the web, said means including a plurality of elongated juxtaposed fluid injection openings on opposite sides of said channel and a plurality of juxtaposed fluid evacuation openings on opposite sides of the channel, said fluid injection openings being angularly oriented with respect to the longitudinal axis of the web; and means for supplying treatment fluid under pressure to said injection openings to inject treatment fluid under pressure into said channel on opposite sides of the web to establish a flow of treatment fluid from said injection openings to said evacuation openings in directions having an angular relationship with the longitudinal axis of the web. 21. Apparatus as claimed in Claim 20, wherein said injection openings comprise a plurality of spaced pairs of juxtaposed elongated slits. 22. Apparatus as claimed in Claim 21, wherein said evacuation openings comprises a plurality of spaced pairs of juxtaposed elongated slits, each of said pairs of injection slits being located between two adjacent pairs of evacuation slits in spaced relationship therewith. 23. Apparatus as claimed in Claim 22, wherein said channel defining means comprises a pair of spaced parallel plates for receiving the web therebetween, each of said pairs of injection openings and each of said pairs of evacuation openings comprising juxtaposed slits in said plates respectively. 24. In apparatus for drying webs of light sensitive material the improvement comprising: means defining a channel for receiving the web, said means including a plurality of elongated spaced injection openings for applying drying fluid to opposite sides of the web and a plurality of elongated spaced evacuation openings for evacuating drying fluid from opposite sides of the web, said injection openings and said evacuation openings being parallel and angularly oriented relative to the longitudinal axis of the web; and means for supplying drying fluid to said injection openings. 25. Apparatus as claimed in Claim 24, wherein said injection openings comprise a plurality of spaced pairs of juxtaposed elongated openings on opposite sides of said channel. 26. Apparatus as claimed in Claim 25, wherein said evacuation openings comprises a plurality of spaced pairs of juxtaposed elongated openings on opposite sides of said channel, each of said pairs of injection openings being located between two pairs of evacuation openings in spaced relationship therewith. 27. Apparatus as claimed in Claim 26, wherein said channel defining means comprises a pair of spaced parallel plates for receiving the web therebetween, each of said pairs of injection openings and each of said pairs of evacuation openings comprising juxtaposed slits in said plates respectively. 28. Apparatus as claimed in Claim 27, wherein said means for supplying drying fluid comprises: housing means defining fluid chambers adjacent said plates on opposite sides thereof; and means for conducting fluid from said chambers to said injection slits. 29. Apparatus as claimed in Claim 28, wherein said housing means comprise a pair of housings positioned in spaced relationship with said plates and said fluid conducting means comprise hollow spacers positioned between said housing means and said plates. 30. Apparatus as claimed in Claim 29, wherein air is evacuated from said channel through said evacuation slits into the space between said housings and said plates. 31. Apparatus as claimed in Claim 24 wherein each of said injection openings is positioned on one side of said channel and in juxtaposed relationship with one of said evacuation openings on the other side of said channel. 32. Apparatus as claimed in Claim 31 wherein said channel defining means comprises a pair of spaced parallel plates for receiving the web there between and said injection and evacuation openings comprise elongated slits in said plates. 33. In apparatus for treating a moving web with a fluid, the improvement comprising: means defining an elongated channel having an entrance for receiving the web and an exit for exiting the material; means for injecting the treating fluid into said channel at a plurality of sites spaced along said channel in a predetermined progression from said entrance to said outlet; means for evacuating treating fluid from said channel at a plurality of spaced sites along said channel in a predetermined progression from said entrance to said outlet; means defining an elongated mixing chamber adjacent said channel; and means for injecting fluid from said evacuation sites into said mixing chamber along the length of said chamber in a predetermined sequence whereby evacuated treatment fluid differing in treatment capability are introduced into the chamber in an ordered sequence; and means for circulating treatment fluid from said outlet to said injection sites. 34. Apparatus as claimed in Claim 33, wherein fluid most depleted in treatment capability are introduced into said mixing chamber at sites furthest from said outlet. 35. Apparatus as claimed in Claims 33 or 34, wherein fluids having differing flow path lengths are sequentially introduced into said mixing chamber. 36. Apparatus as claimed in Claim 35, wherein said evacuation sites alternate with said injection sites whereby each injection site located between two evacuation sites and fluid flows from each injection site to the two adjacent evacuation sites. 37. Apparatus as claimed in Claim 36, wherein each injection site is spaced from each adjacent evacuation site by a distance such that the fluid is evacuated when its boundary layer reaches a predetermined thickness. 38. Apparatus as claimed in Claim 37, wherein each of said sites in said mixing chamber correspond in number to said evacuation sites in said channel, said evacuation sites communicating with said mixing chamber sites whereby the progression of evacuation sites from said entrance communicate with the progression of mixing chamber sites from said outlet respectively. 39. In apparatus for treating light sensitive web or sheet material with a fluid during processing, the improvement comprising: means defining an elongated treatment channel having an entrance at one end for receiving the web and an exit at the opposite end for exiting the web; means for transporting the web through said channel from said entrance to said exit; means for injecting treating fluid into said channel at a plurality of sites along said channel; means for evacuating treating fluid from said channel at a plurality of spaced sites along said channel; means defining an elongated mixing chamber for mixing evacuated fluid prior to recirculation, said chamber having and outlet and a plurality of spaced fluid inlet sites along the length of said channel communicating with said injection sites respectively, the inlet sites in progression from said outlet communicating with the evacuation sites in progression from said exit whereby the most chemically depleted treatment solutions enter said mixing chamber at sites spaced further from said outlet than the less chemically depleted solutions; and means for circulating fluid from said mixing chamber to said injection sites. 40. Apparatus as claimed in Claim 39, wherein fluids differing in flow path length are sequentially introduced into said chamber. 41. Apparatus as claimed in Claim 40, wherein said injection and evacuation sites are equally spaced along said channel and said injection sites alternate with said evacuation sites so that each injection site is between two adjacent evacuation sites. 42. Apparatus as claimed in Claim 41, wherein said injection means and said evacuation means each comprises a plurality of pairs of spaced juxtaposed ports on opposite sides of the web. 43. Apparatus as claimed in Claim 42, wherein each of said evacuation ports and each of said injection ports comprise elongated openings extending transversely of said channel. 44. Apparatus as claimed in Claim 43, wherein said channel defining means comprises a pair of elongated plates having a predetermined space therebetween to define said channel, said elongated openings comprising slits in said plates. 45. Apparatus as claimed in Claim 44 further comprising: means for sensing the effectiveness of the solutions between said mixing tank and said injection ports; and means for replenishing portions of the solution with fresh solution in response to sensing of a particular threshold of ineffectiveness. 46. In apparatus for treating a moving web with a fluid, the improvement comprising: means defining an elongated channel for receiving the web; means for injecting the treating fluid into said channel at a plurality of sites spaced along said channel; means for evacuating treating fluid from said channel at a plurality of sites spaced along said channel; pump means having an inlet and outlet for circulating fluid from said evacuation sites to said injection sites; and means between said evacuation sites and said inlet for sequentially combining fluid evacuated at said evacuation sites to provide uniform combining and mixing of the evacuated fluids between the evacuation sites and the pump inlet. 47. Apparatus as claimed in Claim 46 wherein said fluid combining means comprises means for sequentially combining the evacuated fluid at node points. 48. Apparatus as claimed in Claim 47 further including means between said outlet and said injection sites for uniformly and sequentially dividing the fluid from the pump into fluid streams that are supplied to said injection sites. 49. In a processor for light sensitive web material having a chamber for liquid, the improvement comprising: a plurality of hydrostatic bearings positioned in spaced relationship within the chamber to be submerged in the liquid; means for supplying processing solution under pressure to said bearings; and an aperture means in each of said bearings for emitting said liquid under pressure so as to create a liquid cushion on both sides of the web to thereby support the film in said path without physical contact with bearings. 50. In a processor as claimed in Claim 49, wherein each of said bearings comprise a pair of spaced juxtaposed housings on opposite sides of the web for receiving the liquid. 51. In a processor as claimed in Claim 50 wherein each of said housings include an aperture for emitting said liquid under pressure. 52. In a processor as claimed in Claim 51 wherein each of said bearings comprise flanges attached to the sides of said housings facing the web, said flanges having rectangular openings communicating with said apertures for establishing a cushion of pressurized liquid adjacent to the web. 53. In a processor for light sensitive sheets having a chamber for liquid, the improvement comprising: a plurality of hydrostatic bearings positioned in spaced relationship within the tank to be submerged in the liquid, said bearings being positioned to support a sheet in a predetermined sheet path having a length less than the length of a sheet; means for supplying liquid under pressure to said bearings; and an aperture means in each of said bearings for establishing a liquid cushion on both sides of a sheet to thereby support the sheet without physical contact with the sheet; said. 54. In a processor as claimed in Claim 53 further including roller means for transporting the sheets into the first of said bearings in said path. 55. In a processor as claimed in Claim 54 further including pump means for circulating liquid from the chamber to the hydrostatic bearings. 56. In a processor as claimed in Claim 55 wherein each of said hydrostatic bearings comprise a pair of housings on opposite sides of the sheet path and having interior space for receiving solution from said pump means, said housings including said aperture means. 57. In a processor as claimed in Claim 56 wherein each of said bearings comprise flanges attached to the sides of said housings facing the web, said flanges having rectangular openings communicating with said apertures for establishing a cushion of pressurized liquid adjacent to the web. 58. In a processor as claimed in Claim 57 wherein a plurality of such chambers are provided each containing a plurality of said hydrostatic bearings for successively passing the sheets through different processing liquids. 59. In a processor as claimed in Claim 58 further including roller means between adjacent chambers for transporting the sheets from one tank to the next.

Inventors: DEVANEY MARK J JR, FRANK LEE F, HELFER JEFFREY L, KOCHER HARIBHAJAN S, WAGNER PAUL W, DEVANEY, MARK, J., JR., FRANK, LEE, F., HELFER, JEFFREY, L., KOCHER, HARIBHAJAN, S., WAGNER, PAUL, W.
Applicants: EASTMAN KODAK CO, EASTMAN KODAK COMPANY
Application year: 1991
Main classification: G03D5
IPC codes: G03D5, G03D15