DE69122125T2 - PHOTOGRAPHIC DEVELOPMENT DEVICE - Google Patents

Description

The invention relates to a device for transferring heat energy or chemical mass via a liquid medium and in particular to the transfer in the context of the processing of light-sensitive materials, such as photographic films or papers.

Conventional film processors (or paper processors) do not create sufficient movement at the interface between film and liquid. As a result, a liquid layer is present on the film surface, the reactants of which are consumed and which is enriched with reaction byproducts. During photographic development, this edge layer can limit the transfer rate of the photochemicals to and from the film.

from the film and their concentrations within the film. Any such influence can affect the duration and quality of processing. Analogously, a thermal boundary layer, i.e. an area of reduced temperature, is created in the gas layer that forms on the film surface during the drying process.

Analyses and experimental measurements with conventional processors indicate that there are boundary layers that are thick enough to act as a limiting parameter for the processing rate. The transfer of chemical mass and thermal energy through the chemical and thermal boundary layers is slower than the transfer through the actual film. These conditions result in slow processing speeds, excessively long processing paths, and larger processor dimensions, including the dryer section. In addition, chemical concentrations in the processor's periphery must be sufficiently high to achieve acceptable mass transport rates, resulting in inefficient utilization of processing chemicals. Temperatures in the dryer section of the processor must be excessively high to achieve acceptable film drying times, resulting in inefficient utilization of thermal energy.

The chemical mass transfer rate through this edge layer of the film surface can be approximately determined by the following first order equation:

m/A=D/δΔC

where:

m = mass transfer rate (g/s)

A = Film area (cm²)

D = chemical diffusivity (cm²/s)

δ = surface layer thickness (cm)

AC = concentration gradient (g/cm³)

The ratio D/A is called the mass transfer coefficient. A high mass transfer coefficient results in a high chemical mass transfer rate for a given concentration difference between the film and the solution concentration. The diffusivity is a function of such variables as molecular size and temperature. Although the diffusivity can be increased without any problems, by increasing the temperatures of the developer solution (thereby increasing the chemical mass transfer rates), but this requires the use of more complicated equipment and thus higher processing costs. Alternatively, the chemical mass transfer rate can be increased by reducing the thickness of the chemical boundary layer independently of any increase in temperature.

According to the state of the art, it is known that a stronger movement reduces the thickness of the edge layer and that a reduced edge layer thickness results in a higher density of the developed film. It is also known that higher temperatures increase the chemical diffusivity. It is also known that treating the film by continuous spraying (impinging jets) or vortex flows results in a stronger movement and thus also a significant reduction in the edge layer thickness. The article "Heat Transfer Characteristics of Impinging Two-Dimensional Air Jets", Gordon and Akfirat, Journal of Heat Transfer, February 1966, pages 101-108, describes investigations into the application of air jets in the field of heat transfer. The results presented indicate that very high heat transfer coefficients can be achieved by using direct impingement jets and that the high heat transfer coefficient drops relatively quickly as the distance to the center or stagnation point of the impingement jet increases and that the rapid drop results in an average coefficient over a longer impingement area that is significantly smaller than the maximum value.

To achieve adequate mixing, high eddy current rates or impingement jets were typically used. US-A-3 192 846 describes a processor in which the film rests on thin layers of fluid at high speed and with strong turbulence during transport and causes processing of both film surfaces. US-A-3 372 630 describes a processor in which the film rests on pads of developer fluid and in which the developer is sprayed onto the film or applied to the film in a swirling motion.

The increased movement caused by turbulence or impact jets brings with it the problem that it is very difficult to achieve a uniform treatment process, since any non-laminar fluid state involves uneven fluid movements such as turbulence cavities, eddy currents, etc. Eddy currents also release a large amount of energy where it is not useful, especially in areas that are not part of the film surface. This is due to the "shearing" that occurs within the eddy current field. Large areas, where uniform processing is already difficult, are also difficult to treat with eddy currents and impact jets.

For the reasons mentioned above, the processors currently in use are typically roll-feed processors, in which film or paper is transported through a solution tank by rollers. Although such processors provide more uniform processing than impingement jets or vortex flows, they are bulky, inefficient, and subject to the edge layer problems described above.

The invention defined in claim 1 is based on the object of providing a processor which minimizes the aforementioned effects by providing a laminar Flow of a liquid or gaseous fluid to treat a web-shaped material and reduces the rapid build-up of the edge layer and the resulting reduction in the chemical or heat transfer rate.

In a preferred embodiment, this object is achieved by providing a means which forms an elongated channel for receiving a web-like material (in continuous or sheet form) to be treated by a fluid. The fluid is introduced into the channel at one or more inlet openings. The fluid is removed from the channel at spaced outlet openings. Each inlet opening is located between two outlet openings and is spaced therefrom such that the fluid flows from the inlet opening to the outlet openings in laminar flow and is removed when the boundary layer of the fluid reaches a predetermined maximum thickness.

The invention is explained in more detail below using embodiments shown in the drawing.

Show it

Fig. 1 is a perspective view of a partial section showing a part of a parallel plate processor according to the invention;

Fig. 2 is a schematic sectional view showing the basic fluid circulation paths of a parallel processor according to the invention;

Fig. 3 is a sectional view showing the end wall and the output or input of the processor shown in Fig. 2;

Fig. 4 is a schematic representation of a plurality of processors arranged in series;

Fig. 5 is a sectional view showing another embodiment of the parallel plate processor;

Fig. 6 is a partial sectional view showing the application of the embodiment shown in Fig. 5 for processing photosensitive material;

Fig. 7 is a graphical representation of the edge layer thickness of the processor shown in Fig. 2 in comparison with the edge layer thickness of a prior art processor;

Fig. 8 a force curve to illustrate the stabilizing activity of the fluid cushions;

Fig. 9 is a perspective view of a dryer for photographic film or paper according to the invention;

Fig. 10 is a section through the air bearings shown in Fig. 9;

Fig. 11 the actually measured heat transfer coefficients for the devices shown in Fig. 9 and 10, constructed with a 4 cm wide bearing as opposed to the impingement jet system a commercially available dryer;

Fig. 12 is an exploded perspective view of a portion of a film dryer illustrating another embodiment of the invention;

Fig. 13 is a view similar to that shown in Fig. 12, with parts removed to show the construction in more detail;

Fig. 14 is a plan view of the manifold assembly of Fig. 12 with the cover plate partially cut away;

Fig. 15 is a section along the line 15-15 of Fig. 14;

Fig. 16 is an enlarged detail of the surface 205 of Fig. 15;

Fig. 17 is a plan view of the inlet and outlet openings of the dryer shown in Figs. 12 and 13, with arrows pointing to the fluid flow paths;

Fig. 18 is a side view showing the corrugation of the web material during transport through the dryer shown in Figs. 12 and 13;

Fig. 19 is a side view of an assembled dryer of the type shown in Figs. 12 and 13 with film transport rollers;

Fig. 20 is a schematic representation of another embodiment of the dryer shown in Figs. 12 and 13;

Fig. 21 is a sectional view of a film processor according to another embodiment with schematically illustrated fluid channels;

Fig. 22 is a schematic representation of a film processor according to another embodiment of the invention;

Fig. 23 is a perspective view of a processor according to another embodiment of the invention, with the top removed and a portion of the side walls cut away to show the internal parts;

Fig. 24 is an exploded perspective view of the processor shown in Fig. 23;

Fig. 25 is an end view of parts of the apparatus, such as that shown in Figs. 23 and 24, to illustrate the transport of the film between two processor tanks;

Fig. 26A-G are front views of the distribution plates or walls of the processor shown in Figs. 23 and 24;

Fig. 27 is a front view of the processor shown in Fig. 23 with portions cut away to show the pump chamber;

Fig. 28 is a side view of the processor shown in Fig. 23 with parts cut away to show the pump chamber;

Fig. 29 is an enlarged view of the lower group of hydrostatic bearings of the processor shown in Fig. 23;

Figs. 30 and 32 are enlarged perspective views of portions of a hydrostatic bearing used in the processor of Fig. 23;

Fig. 32A-C are enlarged sectional views 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 shown in Fig. 23.

Embodiments of Fig. 1 - 8

Although the invention is described in connection with the treatment of photosensitive materials, it is to be understood that the invention can be applied 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. The term "fluid" also refers to gaseous as well as liquid states, including air and water.

Referring to Fig. 1 of the drawings, a basic parallel plate processor 8 for circulating a processing fluid in contact with photosensitive materials, such as photographic film (or paper) F. The processor shown in Fig. 1 comprises two spaced parallel plates 10, 12 defining a channel 13 for transporting the film F between these plates. The plates are supported by front and rear walls and are provided with correctly positioned solution inlet openings or slots 16, 18 defining a fluid inlet opening for supplying solution under pressure into channel 13 on opposite sides of the film F. Two manifold plates 20, 22 having openings 24, 26 respectively aligned with inlet slots 16, 18 are connected to the processor plates 10, 12 such that solution is supplied to the inlet slots. Alternatively, the manifold plates 20, 22 may be replaced by a direct feed manifold such as that shown in Fig. 5. The system piping has been omitted in order to illustrate the underlying boundary layer concept more clearly.

The basic solution flow path is shown by the arrows in Fig. 1. Pressurized fluid enters channel 13 on either side of film F, creating a cushion of fluid under pressure on opposite sides of the film which supports the film and allows it to travel through channel 13 without contact with plates 10, 12. The fluid moves in laminar flow to the ends of channel 13 for discharge. If the treatment fluid is a liquid, it may be collected in a collection tank (not shown) and returned to the manifold via pumps and tubing (also not shown). The solution may also be replenished as described below. The processor can of course also be used as a diving device, like the processor shown in Fig. 5 and 6.

The fluid pads on opposite sides of the film exert pressure on the film and stabilize it so that it is held in a central position between the plates 10, 12. As the film moves away from this central position, it moves closer to one of the two plates. Due to the closer proximity to one plate, the thickness of the flow channel on that side of the film is reduced, thereby reducing the flow within the channel on that side. Due to the reduced flow rate, the pressure across the inlet opening on that side of the film drops. This increases the fluid pressure in the thinner channel relative to the thicker channel, thereby exerting a force on the film that returns it to its central position. This type of stabilization is shown by the curve in Fig. 8, which is a curve of force on the film (dynes) versus film distance from the channel center.

According to the invention, the length L of the channel 13 on each side of the inlet slots is finite in relation to the increase in the thickness of the chemical boundary layer 13, so that the solution flows out of the ends of the channel 13 when the boundary layer reaches a thickness at which the solution no longer effectively transfers chemicals (or heat). Maximum transfer occurs in the region of the inlet slots 16, 18. The further the solution moves away from the inlet slots in the paths indicated by the arrows, the thicker the chemical boundary layer B becomes, as shown in Fig. 2. At the point where the boundary layer has reached a thickness where the chemical or heat transfer efficiency falls below a desired value, the solution flows preferentially out of the ends of the channel and is either returned or refilled. This concept maximizes the effectiveness of the chemical or heat transfer process.

The effectiveness of the chemical or heat transfer process is improved in two ways. First, by minimizing the length L, the length over which the boundary layer can develop. Second, the system parameters are chosen to achieve a reasonably high fluid velocity in the laminar flow region to minimize the rate at which the boundary layer can grow. A small plate spacing is used to achieve high fluid velocities with laminar flow. A short spacing and high-velocity laminar flow result in a slowly developing boundary layer and efficient chemical or heat transfer with laminar flow.

The invention uses laminar flow to advantageously achieve chemical or heat transfer rates that exceed those achieved by most vortex flows, with a fraction of the power required. The power requirements are very low because much of the fluid flow energy is dissipated only at the film surface, due to shear forces between the fluid and the film. This represents a unique alternative to the use of vortex flows, which release 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 way. It was assumed that the similarities between heat and mass transfer allow the conclusions obtained from heat transfer studies of incompressible flows to be applied to the transfer of chemical mass in the liquid regime.

There are several ways to express the efficiency of heat or chemical mass transfer. As described in Fluid Dynamics and Heat Transfer, Knudsen and Katz, McGraw Hill, 1958, page 366, eg. 13-12, the heat transfer coefficient hheat of a laminar flow along a surface as a function of X (distance of the leading edge of a flow path) can be expressed by the following equation:

where:

K = thermal conductivity

α = thermal diffusivity = K/CpP

C = Velocity profile = u∞/y

u∞ = velocity of the fluid parallel to the surface

y = distance to surface

Cp = specific heat of the fluid

P = fluid density

To develop the mass transfer analogy, the following assumptions can be made:

For water: CpP = 1; α; = K

For liquid: K = D (chemical diffusivity)

The chemical mass transfer coefficient can therefore be expressed by the following equation:

This equation defines the relationship between the chemical mass transfer coefficient and the fluid properties for the particular parallel plate flow concept of the processor of Figure 1 and other embodiments described below. From this equation, it can be determined which variables would need to be manipulated to maximize this coefficient and the resulting mass transfer rate. This invention is particularly based on the finding that hCHEM can be maximized by increasing u, decreasing y, and decreasing x.

Assuming a typical processing fluid temperature of 35ºC, the following variables have the values given:

D = 5.0 x 10⊃min;⊃6; cm²/s

u∞ = 25.4 cm/s

y = 0.075cm

The value of hCHEM(x) increases as the value of x decreases. An average of hCHEM over distance L can be obtained by integrating hCHEM(x) over a distance of X = L as follows:

If L is assumed to be 1.0, then

The table below shows the ranges for the system variables from which minimum, maximum and nominal values of the chemical mass transfer coefficients were calculated.

For CHEM max.:

u∞ = 100 cm/s

y = 0.05cm

x = 0.25cm

CHEM = 0.0086 cm/s

CHEM nominal:

CHEM = 0.0030 cm/s

(Variables as previously specified)

CHEM min.:

u∞ = 20 cm/s

y = 0.10cm

x = 2.5cm

CHEM = 0.0018 cm/s

Taking into account the above data, it is obvious that a chemical mass transfer value in the following range gives optimal results for the invention:

0.010cm/s ≥ h ≥ 0.001cm/s

This range is based on a chemical diffusivity D of 5.0 x 10-6cm2/s. Other chemicals would have different values, even if the solution is the same. Of course, each chemical has its own specific boundary layer. This mathematical determination of the relevant dimensions therefore results in a fluid treatment device with laminar fluid flow, maximizing the efficiency of the treatment fluid by preventing the boundary layer thickness from increasing beyond a predetermined value.

The maximum thickness is defined to maintain an aqueous chemical mass transfer rate that exceeds the transfer rate within the film by a reasonable amount. To compare the value of hCHEM with that expected to be obtained in conventional tank and roll-conveyor processing, the hydrodynamics of roll-conveyor processing were considered analogous to liquid flow over a fixed flat plate. The equations giving the chemical mass transfer coefficient for this condition are described in Fluid Dynamics and Heat Transfer, Knudsen and Katz, McGraw Hill, 1958, page 482, Figures 17-39. The appropriate equation is:

Where:

D = chemical diffusivity

u ∞= free flow velocity

v = kinematic viscosity

By integrating over the distance x = L, the mean value of hCHEM over the distance L can be determined:

For comparison, assume that for the roll transport D = 5 x 10-6 cm2/s (as before), L = 1.0 cm, v = 0.0072 cm2/s, liquid temperature = 35ºC. Based on these assumptions, CHEM = 0.0022, 27 percent less than the 0.0030 achieved with the invention. In addition to the higher mean value of hCHEM, the invention has many other advantages. Most notable is the fact that a value of 0.002 for CHEM would be extremely difficult to achieve for a number of reasons. For example, roll spacing of 1.0 cm would require very small rolls spaced very closely together and requiring many support members. In addition, the factors previously mentioned for the roll transport apparatus assume that the rolls reduce the chemical boundary thickness to zero as the film contacts each successive roll. This is not the case. The film "slides" on each roll on a liquid cushion and leaves a residual chemical layer behind. This increases the mass transfer coefficient by a fixed amount over the entire film surface. In addition, the film must move at high speed in roll-transport tank processors, which causes problems with the reliability of the transport. In addition, sustainable development times require very large machines.

The same parameters cannot be used for a roller transport tank processor for practical reasons. L would be 4 cm or more, u∞ would be in the range of 2.5 - 5.0 cm/s, with a worst case value of 5.0 cm/s being more likely. Under these constraints, CHEM would be 0.00048-84 percent smaller than the value of 0.030 calculated for a parallel plate processor according to the invention.

Figure 7 is a graphical representation of the results obtained with a chemical treatment device according to the invention using hydroquinone as the treatment fluid compared to a conventional roller conveyor processor. Curve A shows the plot of the edge thickness versus the distance to the leading edge of a fluid path in a prior art roller conveyor processor. Curve B is a similar plot for a prototype processor according to the invention. Curve B represents the edge thickness with the inlet slots at the far left and right of the graph and the outlet slot in the middle. The difference in the average edge thickness (dashed lines A1 and B1) is large and indicates the unexpected results obtained with the invention.

Referring to Fig. 2 of the drawings, there is shown a parallel disk processor 28 which implements the method described in connection with Fig. 1. This processor comprises two spaced parallel plates 30, 32 having two correctly positioned inlet slots 34, 36 and two pairs of correctly positioned outlet slots 38, 40 and 42, 44. The plates may rest on end walls (not shown) similar to those shown in Fig. 1 to form a channel 48 therebetween through which the film F is transported by means of rollers of the type described below.

The solution circulation paths are indicated in Fig. 2 by arrows which also indicate the system piping in schematic form. The processor shown can of course have additional inlet and outlet slots by extending the plates 30 and 32. The circulation pattern shown schematically can be repeated by providing additional alternative inlets and outlets for the solution, depending on the requirements of the particular application.

Referring to the recirculation pattern, solution is supplied to inlet ports 34 and 36 from mixing tanks 49 and 50, respectively. Fluid exits channel 48 through outlet slots 42, 44 and 38, 40, as indicated by the arrows. A portion of the solution exiting through slots 38 and 42 may be returned to mixing tank 49 by pumps 52 and 54, respectively, with the remainder being returned to adjacent mixing tanks (not shown) in the series, as indicated by the arrows. When refilling is required, fresh solution may be supplied to tank 49 by pump 56. The need for such refilling may be determined by sensors 60, 62 connected to the return inlet channels to mixing tank 49 and connected to a control means 64. which activates the pump 56 when necessary. Control means 64 can also be arranged on the control pumps 52, 54.

Slots 36, 40, 44 are similarly connected to mixing tank 50, pumps 66, 68 and 70 which provide circulation and refilling in the same manner as described in connection with tank 49. Pumps 66, 68 and 70 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 refill systems have been shown. Those skilled in the art will recognize that tanks 49, 50 have been replaced by a single tank connected to both inlet slots 34, 36. Solution can be recycled from outlet slots 42, 44 and 38, 40 into this single tank. Alternatively, fluid channels and pumps of sufficient capacity could be used without a separate tank.

In operation of the processor shown in Fig. 2, solution is supplied from tanks 49, 50 to inlet slots 34, 36 to thereby create pressurized solution pads on both sides of the film. From each slot, solution flows to the right and left of both sides of the film as shown by the arrows. At each outlet slot, solution exits from the two adjacent inlet openings as indicated by the arrows. If the processor were a simple processor provided only with the openings shown in Fig. 2, solution would exit from slots 42, 44 and 38, 40 and enter via slots 34, 36. Such a processor would be provided with a slot 76 in an end wall 78. to allow the film to exit between two doctor and transport rollers 80 as shown in Fig. 3. A similar construction may be provided at the entrance to the processor to allow the film to be transported into the processor.

Similar to the processor shown in Fig. 1, the solution entering channel 48 has maximum chemical or heat transfer adjacent to inlet slots 34, 36. As it flows toward, for example, slots 38 and 40, the boundary layer increases in thickness as shown in Fig. 2. As in the processor shown in Fig. 1, it is desirable for the solution to exit when the boundary layer reaches a thickness that makes processing inefficient. Accordingly, the length of channel 48 between adjacent slots is sized to allow the solution to exit an outlet slot when a predetermined boundary layer thickness is reached. As previously mentioned, the maximum thickness is defined to maintain an aqueous chemical mass transfer rate that exceeds the transfer rate within the film by a reasonable amount. As discussed in connection with the embodiment of Fig. 1, the plate spacing is kept small in order to achieve high velocities in the laminar flow region.

Those skilled in the art will recognize that by providing appropriate valves and tubes, different solutions can be sequentially fed to the processors described herein to subject the film to a series of treatments, e.g., developing, fixing, washing and drying. Alternatively, a series of separate processors can be provided as shown in Fig. 4, each processor subjecting the film to a different treatment. Nip rolls 80 would be provided at the entrance and exit of each processor to transport the film along the treatment path. The exit rolls of wet solution processors would be doctor rolls to remove excess solution.

If the system of Fig. 4 is used to process sheet film (e.g., X-ray film), the processor would be sized and spaced such that the distance between adjacent pairs of squeegee rollers is less than the length of the sheet. The invention has particular utility in sheet film processing since the increased processing efficiency allows the use of smaller processing units to reduce equipment size or to allow for the processing of small sheets of film.

Referring to Figures 5 and 6 of the drawings, another embodiment of the invention for use as a dipping device is described. This embodiment includes a parallel plate processing unit 82 having two parallel plates 84, 86 positioned and supported by side walls 88 to form a channel 90 for receiving the web of photosensitive material F, such as photographic film. The plates 84, 86 are provided with first and second pairs of correctly positioned inlet slots 92, 94 and 96, 98 on opposite sides of two correctly positioned outlet slots 100, 102. The inlet and outlet slots are spaced and sized as previously described to remove fluid from the channel 90 when the edge layer of the processing fluid becomes so thick that its use becomes inefficient.

The plates 84, 86 are connected to distributor plates 104, 106, respectively, which in turn are connected to the outer plates 108, 110. The distributor housings 112, 114 are connected to plates 108, 110, respectively, and have chambers for receiving the pressurized treatment fluid via conduits 116, 118, respectively. The fluid pressurized in containers 112, 114 flows to the inlet ports 92, 94 and 96, 98 via openings in the plates 104, 108 and in the plates 106, 110 and is fed to the channel 90 to cause laminar flow of the fluid on the opposite sides of the film in one direction toward the outlet ports and in the opposite direction toward the open ends of the channel 90. The fluid removed from the channel 90 through the outlet openings 100, 102 flows out the sides of the unit via openings in the plates 104, 106. As described in connection with Fig. 2, additional inlet and outlet openings may be provided, depending on the requirements of a particular treatment process.

Fig. 6 shows the use of a processor of the type shown in Fig. 5 or Fig. 1 to process photographic film. In particular, an elongated housing is provided with a plurality of processing chambers 128, 130, 132, 134 for film development, fixing, washing and drying. A processing unit 82 is arranged in each chamber, the units 82 in the chambers 128, 130, 132 being immersed in the liquid processing solutions as shown. Each processing unit may be provided with a recirculation system such as that shown in connection with the unit 82 in chamber 128. In its simplest form, the system would comprise a pump 136 having its inlet connected to the chamber 128 and its outlet connected to the manifold housings 112, 114, wherein Fluid is continuously circulated from the chamber to the inlet ports 92, 94 and 96, 98. Fluid exiting the outlet ports 100, 102 and the ends of the channel 96 is mixed with the fluid in the chamber 128. As will be appreciated by those skilled in the art, the mixing action can be enhanced by providing a mixing impeller (not shown) in the chamber 128. In addition, replenishment means (not shown) can be provided to periodically supply fresh fluid to the system.

The film transport means comprise input and output chutes 140, 142 through which the film enters the first chamber 128 and through which the film exits the last chamber 134, respectively. Identical chutes 144 and pairs of nip rollers 146, 148 (one pair between each two adjacent chambers) transport the film from chamber to chamber. In each processing unit, the associated chutes feed the film to and from the channel 90 and the nip rollers.

Embodiment of Fig. 9-11

Referring to Figures 9 and 10 of the drawings, an embodiment of the invention is shown in a film or paper dryer 160 comprising two correctly positioned air bearings 162, 164. The bearings 162, 164 comprise rectangular housings having side walls, end walls and cover plates (not shown) secured to spaced parallel plates 166, 168 respectively. The plates are secured in spaced relation to one another by spacers 170 to obtain the desired spacing described below. The plates 166, 168 are provided with central longitudinal openings or slots 172, 174 for admitting air under pressure into the space between the plates from the interior of the bearing housings. A shaft 176 (one of which is shown in Fig. 10) is connected to a pressurized air source in each housing.

As shown in Fig. 1, the bearings 162, 164 are arranged to form a channel 178 for a web material W, which may be photosensitive. The web material W may be transported to the channel 178 by two nip rollers 180, which in turn may comprise the exit doctor rollers of a washing section of the film processor. Preferably, the air bearings 10 are rotated 15 degrees to the longitudinal axis of the rollers to avoid aeroelastic flutter in the leading and trailing sections of the web material.

During operation of the dryer, pressurized air is supplied from the ducts 176 to the bearings 162, 164 and through the slots 172, 174 to the channel 178 to form pressurized regions on opposite sides of the film. As a result, laminar air flow occurs in the opposite directions to each slot relative to the film path. The air streams exit the channel 178 on the opposite sides of the plates 166, 168.

The thickness and length of the channel 178, the width of the slots 172, 174 and the air pressure of the bearings 162, 164 are parameters which are preferably selected to control the edge layer thickness and to minimize the distance over which the edge layer can develop. In addition, the system parameters are selected to provide sufficiently high fluid velocities in the region of laminar flow to minimize the growth rate of the edge layer. As a result, a heat transfer rate is generated in the fluid which increases the heat transfer rate within the film or paper. A small plate spacing helps achieve high fluid velocities with laminar flow. These concepts have been described in more detail previously.

According to the invention, the thickness of the channel 178 is preferably 1.5 to 2.3 mm. The length of the fluid path in the film direction is between 7.6 to 20.3 mm, depending on the total amount and rate of heat transfer required. The slots 172, 174 in the plates 166, 168 are preferably 0.38 mm wide. The air pressure within the bearing is typically 86.3 mm H2O at a temperature of 32 to 54 degrees, depending on the required drying rate and the particular film properties, such as the gelatin content, etc.

The pressure drop in the slots 172, 174 is approximately 50 percent of the existing pressure. The pressure at the film plane is dependent upon the rate of air flow through the slot. The higher the flow rate, the greater the pressure drop. As previously discussed, as the film shifts from a central position to either plate, a pressure gradient is established between the upper and lower sides of the film, returning the film to its central position. Assuming the film is in its central position in channel 178, the high velocity air flow from the slots above the film and from the sides of the bearings causes a reduction in the previously discussed edge layer thickness and thus better heat and water vapor flow. The limitation of the edge layer thickness is a function of the channel size, the channel length and the pressure of the air supplied through the slots. The heat flow of the film is a function of the air temperature and also the Surface layer thickness. Water vapor removal is primarily a function of surface layer thickness and the rate at which heat can be applied to evaporate water in the gelatin coating of the film or paper.

Fig. 11 shows curves of the actual measured heat transfer coefficients for a dryer according to the invention (curve A) with 4 cm wide bearing plates 166, 168 and a commercially available M6B X-OMAT dryer (curve B) manufactured by the Eastman Kodak Company. As can be seen in Fig. 11, the average value for the M6B dryer is about 1.76 kcal/hr per 0.09 m² per 0.55°C, while the dryer according to the invention has an average value of about 9.6 kcal/hr per 0.09 m² per 0.55°C. This significant increase in efficiency indicates the superior performance of the device according to the invention. Most important is the fact that this improvement in drying efficiency was achieved with a much smaller and less expensive dryer.

Different web materials may require longer or shorter bearing widths (flow path lengths) or even multiple bearings.

The embodiment shown in Fig. 9 - 11 achieves higher heat transfer coefficients, which leads to shorter drying times, smaller and simpler dryers, lower drying temperatures and less energy consumption. The air storage of the film or paper in the dryer reduces the risk of film scratches or other artifacts in the dryer. Lower energy requirements mean less heat dissipation to the environment, less cooling required for the processing chemicals and no special power connection for the processor. Thanks to the simple The design and small size of the dryer also means that fewer components are required, which contributes to considerable cost savings.

Embodiments of Fig. 12-20

In the apparatus shown in Figures 1-8, fluid is supplied to the channel through correctly positioned inlet slots and removed from the channel through correctly positioned outlet slots. The slots extend transversely and substantially perpendicular to the film axis. Each correctly positioned path of the inlet slots is arranged between the two correctly positioned pairs of outlet slots so that fluid flows in opposite directions from each inlet slot to the adjacent outlet openings.

Although the device described in Fig. 1-8 achieves a mass and heat transfer rate that is significantly higher than that of the prior art devices, where the sheet material does not contact the channel surfaces, it has been found that a certain instability of the sheet material can occur, which can lead to material vibrations, especially when this device is used to dry the sheet material with air. Such conditions do not affect the performance of the device described, but leave room for further improvement of the results achieved.

Due to the alternating arrangement of inlet and outlet openings, there are also alternating areas of high and low pressure in the film channel. The pressure of the fluid on each side of the web material reaches a maximum at the inlet openings and a minimum at the outlet openings. Accordingly, the web material is the inlet openings and minimally supported at the outlet openings. If the inlet and outlet openings extend perpendicular to the film axis, then low pressure regions extend transversely and provide minimal support to the web material, thereby subjecting it to gravitational displacement. Due to the mutual arrangement of these high and low pressure regions, the web material may even vibrate or oscillate, although it does not touch the surfaces of the channel.

The condition described is particularly likely to occur when the leading or trailing edge of a web material is transported through the channel. Since the end is free, it can act as a cantilever beam and is even more subject to the high and low pressure zones. The compressive forces can even lift the end of the web material, especially if the treatment fluid is air. These effects are more pronounced when drying large sheets or materials, such as photographic film.

In connection with this embodiment, the previously described condition is minimized by arranging the inlet and outlet openings at an angle to the longitudinal axis of the web-shaped material. As a result, the high and low pressure regions extend at an angle to the film. In this arrangement, each inlet opening generates a fluid flow with a flow component which runs at an angle to the longitudinal axis of the web-shaped material in the material transport direction and with a second flow component which runs at an angle to the longitudinal axis opposite to the transport direction of the web-shaped material. The components in the direction of web transport minimize the lifting of the sheet material by the treatment fluid and have a stabilizing effect. The pressure exerted by the fluid from the angled openings helps to create pressure waves in the sheet material which extend at an angle to the longitudinal axis of the sheet material. Such waves help to strengthen the sheet material and make it less sensitive to bending and vibration. Referring to Figures 12 and 13 of the drawings, there are shown two spaced plates 210, 212 which are connected together and spaced apart by spacers 213 to form a channel 214 (Figure 15) which receives a sheet material W, for example photographic film. The plates 210, 212 have a plurality of elongated, spaced apart fluid inlet openings or slots 216 and a plurality of elongated, spaced apart fluid outlet openings or slots 218. When the plates are joined together, the openings 216 in the plates 210 and 212 are aligned in the correct relationship to each other. Likewise, the openings 218 in the plates 210 and 212 are aligned in the correct relationship to each other. The openings 216 and 218 alternate so that each pair of correctly positioned inlet openings is located between two pairs of correctly positioned outlet openings. As will be described in detail below, all of the openings 216 and 218 are arranged parallel to each other and form an axis with an angular relationship to the longitudinal axis of the film. This angular arrangement of the openings to the longitudinal axis of the film is particularly evident in Fig. 17. Although a 45 degree angle is preferred, improved positional stability can be achieved at angles between 15 and 90 degrees.

A plurality of elongated spacer hollows 222 are secured to the plates 210 and 212, with the hollows of the spacers communicating with the openings 216. Two plates 224, 226 are disposed over the spacers 222 on the sides opposite the plates 210 and 212, respectively. Slots 228 in the plates 224, 226 communicate with the hollows of the spacers 222 to supply fluid to the slots 216.

Two housings 230, 232 are attached to the plates 224 and 226, respectively, to form distribution chambers 234 and 236 which supply air to the openings 228. The ends of the chambers 234, 236 may be sealed by end plates 238, one of which is shown in Fig. 12. Each housing 230, 232 is provided with an air inlet opening 240. The fans 242, 244 (Fig. 12) supply pressurized air to each inlet opening.

Each of the plates 224, 226 can form a structural unit with the associated housing and thus encompass a wall of this housing in order to form a housing with chambers for the supply of fluid to the channel 214.

To complete the assembly, the plates 210, 212, 224 and 226 are connected together by screws 246 extending through the openings in the plates and through the spacers 213 (Fig. 12). When so assembled, the channel 214 between the plates 210, 212 has a thickness equal to the length of the spacers 213.

During operation of the dryer, pressurized fluid (in this case air) is supplied to the chambers 234, 236 via fans 242, 244 to build up pressure in the chambers. Air flows from the chambers 234, 236 through slots 228 and the Interior of spacer hollows 222 to slots 216. Air is supplied to channel 214 on opposite sides of the film through slots 216 to create regions of pressurized air on opposite sides of the film. From slots 216, air flows to adjacent outlet slots 218 as shown by the arrows in Fig. 17 and is discharged into the space between plates 210, 224 and between plates 212, 223.

The slots 216 are preferably sized and spaced from the slots 218 so that the air is removed when the edge layer reaches a thickness that makes heat transfer between the air and the film inefficient. In particular, heat transfer is improved by minimizing the length of the flow path from an inlet slot to an outlet slot to minimize the length over which the edge layer can develop and by minimizing the rate at which the edge layer can grow. The latter is achieved by using fairly high fluid velocities in the laminar flow regime. This concept has been explained in detail previously.

Referring to Fig. 19, a side view of the assembled dryer is shown with the web material W being transported through the processor by two pairs of nip rollers 250 and 252 located adjacent the entrance and exit of the channel 214, respectively. These rollers may be driven by motors 254, 256, as shown. When drying web material in sheet form, the rollers would be spaced apart by an amount less than the length of the sheet so that the Sheet is grabbed by the exit rollers before it leaves the entry rollers.

Taking into account the angular relationship of the slots 216, 218 to the longitudinal axis of the web, it can be seen from Fig. 17 that the air from each slot 216 has 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 component at a 45 degree angle to that axis. This increases film stability by minimizing the lift caused by the air flowing in the opposite direction to the film transport direction. As previously explained, the alternating regions of high and low pressure extend at an angle to the film and establish a waveform pattern as shown in Fig. 18. Because this force pattern is angularly aligned with the film, it tends to give the film a shape that has a higher bending moment, making it more difficult to deform the film. These conditions, combined with the inherent stability created by fluid flow on opposite sides of the film, result in higher strength, less vibration, and greater bending resistance.

The device thus effectively contributes to the basic stability through laminar air flows on opposite sides of the web-like material, which, as previously described, is achieved by a simply aligned force pattern over the web-like material.

Another embodiment is shown schematically in Fig. 20. In this embodiment, a dryer 260 provided with a channel 262 having a plurality of inlet slots 264 and a plurality of outlet slots 266, which are not shown to scale here. In this embodiment, the inlet and outlet slots alternate on each side of the channel, as in the previous embodiment. However, an outlet slot 266 is always arranged in the correct relationship to an inlet slot. This creates a force gradient on the sides of the film, as indicated by the vertical arrows which indicate the direction of the force. The film is consequently corrugated, as shown in the figure. If the slots are angularly aligned to the film axis, the corrugation increases the bending resistance of the film significantly.

The device shown in Fig. 12-20 thus contributes greatly to increasing the stability of a moving web material during transport through a fluid treatment channel and finds particularly advantageous use in a dryer. The fluid flows on the opposite sides of the web material support and stabilize the web material. The angular orientation of the fluid inlet and outlet openings contributes to further stabilizing the web material by minimizing the stroke and by creating a wave force pattern on the web material which increases the strength of the web material and reduces the vibration of the web material.

Embodiments of Fig. 21-22

According to these embodiments, a device for treating web-shaped material, such as a film or paper processor, comprises means for forming a channel through which the web-shaped material is transported. The treatment fluid is supplied to the channel at spaced apart inlet ports on opposite sides of the web material and is removed from the channel at spaced apart outlet ports on opposite sides of the material. The inlet and outlet ports alternate so that the supplied fluid is removed at adjacent outlet ports. The streams of removed fluid are combined such that streams of different flow path lengths and chemical depletion are mixed sequentially before being reintroduced into the channels. This mixing results in a uniform composition of the reintroduced fluid.

Referring to Figure 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 of photographic film (in continuous or sheet form). The plates are supported by two end walls 317, 318 having slots 320, 322, respectively, for the entry and exit of the film.

The film F is moved through the channel in the designated direction by means of transport means comprising two pairs of nip rollers 324, 326. One or both pairs of nip rollers may be motorized, depending on whether the film F is used in sheet or web form. When sheet film is processed, the length of the channel 316 is less than the sheet length so that the rollers 324 grip the sheet before it leaves the rollers 326. When a liquid solution is applied to the film, the exit rollers 324 may also include doctor rollers to remove excess solution.

The plates 312, 314 are provided with a plurality of spaced, correctly positioned inlet slot pairs 330, 332, 334 and a plurality of spaced, correctly positioned outlet slot pairs 336, 338, 340, 342 forming inlet and outlet openings. The inlet and outlet openings extend transversely to the channel and are at least as long as the film is wide. The slots are arranged alternately such that each pair of correctly positioned inlet slots lies between two spaced pairs of correctly positioned outlet slots, the distances between adjacent slots along the film path being equal.

In operation, fluid supplied under pressure to channel 316 forms pressurized fluid pads on opposite sides of the film. These fluid pads support the film and cause laminar fluid flow on each side of the film to the adjacent outlet slots where it is discharged from the processor. As described in connection with the embodiments of Figures 1-8, the spacing between adjacent slots is selected such that withdrawal of the flow fluid occurs when its boundary layer becomes so thick as to render processing of the film inefficient. These conditions have been previously described in more detail so that further description is not necessary here.

The circulation and refill system is shown using lines and arrows for a better overview. The arrangement of suitable pipes to achieve the indicated flow and mixing is clear to the expert in fluid technology and pipe construction, so that a further description does not seem necessary here. The system for Circulation and mixing of the fluid is identical above and below the film, although only the upper system is described in detail here.

Referring to the drawing, the recirculation system includes a mixing means comprising two spaced parallel plates 350 and 352 forming an elongated mixing chamber 354. The plates 350 and 352 may be supported by end plates 356 and 358. Alternatively, the plates 350 and 352 and one of the end plates may be formed into an integrally molded housing with the other end plate secured to this structure.

The end plate 358 may be provided with an elongated, funnel-like outlet 360 connected to a circulating pump 362. The plate 352 is provided with a plurality of inlet openings 364, 366, 368, 370 which are connected to the discharge openings 336, 338, 340, 342, respectively, by suitable pipes, as shown schematically. The pump 362 is connected to the inlet openings 330, 332, and 334 by suitable pipes and/or manifolds, as shown schematically. The outlet of the pump may be provided with a sensor 372 to determine the condition of the circulating fluid. A control means 374 responsive to the output of the sensor may be arranged to open a refill valve 376 when the fluid condition requires the addition of fresh solution. Alternatively, the fluid may be disposed of or recycled to remove undesirable by-products and so minimize environmental impact.

During operation of the mixing system, part of the fluid supplied to opening 334 is removed at opening 342, i.e. the opening furthest from the outlet 360 of the mixing chamber. Since this fluid stream has treated the leading end of the film, it is the most chemically loaded. Feeding the mixing chamber at the end remote from the outlet allows the stream to mix with the less chemically loaded fluid streams throughout the length of the mixing chamber.

The other portion of the fluid supplied at port 334 and a portion of the stream supplied at port 332 is removed at port 340 and enters the mixing chamber at port 368, the second furthest port from the chamber outlet. These two streams mix at ports 340 and 368 before entering the chamber. The combined stream is then mixed with the fluid removed from port 342. Thus, in the area of the mixing chamber adjacent to port 368, the three streams are essentially mixed, with all streams initially having different chemical contents. The streams also differ in the timing of their delivery to and removal from the processor due to the different flow path lengths from the pump to the inlet ports. This time difference further increases the mixing process.

The sequential mixing process continues as the mixed streams flow to the outlet 360. At port 366, a mixed stream containing portions of the fluid streams added at ports 332 and 330 enters the chamber and mixes with the fluid stream composed of the fluids from ports 368 and 370. This combined mixed fluid stream mixes with the remainder of the stream added at port 330 in the region of port 364. In this way, the fluid exiting the outlet of the chamber Fluid is thoroughly mixed and has a uniform composition.

The mixing process takes place in all parts of the system, including the pump 362, the inlet ports to the mixing chamber, and the inlet and outlet ports. The device thus comprises a closed processing circuit in which essentially all fluids are mixed and circulated very often. All fluids also flow through a single area (the pump), which further enhances the mixing process before the fluid is redistributed. The high turbulence within the pump ensures complete mixing.

The advantages of the mixing process are shown below. The most chemically loaded fluid streams are fed sequentially into the mixing chamber at points progressively spaced in order of depletion, with the most depleted streams fed at the end farthest from the outlet, while the least depleted streams are fed closest to the outlet. In addition, adjacent streams are combined in the outlet ports before entering the mixing chamber to enhance the mixing process. The mixing process is enhanced by the different lead times of the fluid streams. For example, the fluids in the short flow paths with varying chemical concentrations are quickly mixed with the fluids from the medium and long flow paths. Similarly, the addition of make-up solution in the shorter path (outlet of pump 362) is quickly distributed to the other longer paths. This results in a strictly ordered, sequential mixing process with exemplary uniformity. Solution. The mixing process also requires no moving parts.

An apparatus incorporating the concepts described here can circulate the entire solution every 5 to 10 seconds. By comparison, a typical roller transport tank processor has stagnation areas where the fluid is only circulated every 5 to 20 minutes. This comparison demonstrates the superior performance achieved with the closed mixing process of the invention.

Referring to Figure 22 of the drawings, another embodiment of a closed mixing system is shown. This embodiment also includes two parallel plates similar to those of the embodiment of Figure 21. It also includes spaced slots in the plates to form a plurality of inlet ports 310 and a plurality of outlet ports 312, the ports alternating as in the embodiment of Figure 21 so that an inlet port is located between two adjacent outlet ports. The spacing between the ports is such that fluid flow is removed when the boundary layer reaches a thickness that makes treatment of the film inefficient.

The piping of the system shown in Fig. 22 is shown schematically to illustrate the operation of the invention. It will be understood, however, that the requirements of suitable manifolds and piping to achieve the indicated circulation are within the knowledge of one skilled in fluid mechanics and piping. As in the case of the embodiment of Fig. 21, the systems on both sides of the film are identical with correctly positioned inlet and outlet ports. Accordingly, only the upper side of the film is shown and described.

Referring to the recirculation system, the solid lines indicate the flow paths of the fluid from the pump 314 to the inlet ports 310. The dashed lines indicate the flow paths of the fluid from the outlet ports to the pump inlet. In the supply system, it can be seen that the output of the pump is divided evenly and sequentially at the node or branch points 316. It can also be seen that the withdrawn fluid is brought together evenly and sequentially at node or branch points 318. In the withdrawal system, all fluids are progressively mixed with each other after contact with the film or paper. All fluids also pass through a single area (the pump) before being recirculated. Thanks to the strong turbulence within the pump, the fluid streams are completely mixed. In addition, the branching or junction points provide for a sequential mixing of the streams with different chemical depletion and lead time before they enter the pump.

Embodiments of Fig. 23-33

US Patent 4,994,840 describes a processor for photographic film or paper having a floating chamber submerged 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 web of film or paper is inserted into the end of a processing channel. The processing fluid is supplied at the opposite ends of the channel and released at the midpoint of the channel.

According to this embodiment of the invention, a plurality of hydrostatic bearings are arranged in spaced relation in a processing chamber filled with processing solution. The processing solution is circulated by a pump from the chamber to a manifold and to the bearings. The solution flows out through the bearings in contact with the film such that the film does not contact the bearing surfaces.

Referring to Figure 23 of the drawings, there is shown a film processor 410 having a container or tank 412 comprising a chamber 413 for the processing solution or wash water and a housing or tank 416 for a pump 418. Between tanks 412 and 416 are a plurality of superimposed plates 422, 424, 426, 428, 430 and 342 (Figure 26) which form the solution distribution channels for the processor. Plate 422 may comprise a side wall of tank 412. Plates 424-432 are suitably connected to walls 422 of container tank 412 as shown in Figures 23 and 27. Tank 416 may be attached to the end plate as shown.

A plurality of elongated hydrostatic bearings 438 are arranged in chamber 414 in parallel spaced relationship as shown in Figure 26G. This is a view of end wall 422 with the bearings attached thereto to create a curved film path as described below. The ends of the bearings 438 are attached to plate 422. As described in more detail below, the bearings 438 are immersed in processing solution in tank 412 and have internal cavities that are filled with processing solution through the distributor formed by plates 422, 424, 426, 428, 430 and 432.

The plate or wall 432 (Fig. 26F) includes a pump side or pump inlet and pump outlet plate and an inlet opening 440 communicating with an inlet or suction chamber 422 (Figs. 27 and 28) of the tank 416, and an outlet opening 444 for removing solution from the high pressure or outlet chamber 446 of the tank 416. The pump impeller 448 is disposed in the outlet chamber 446 and is rotated by the pump shaft 450 to circulate the solution from the chamber 442 into the chamber 446 through openings 449.

Plate 430 (Fig. 26E) comprises a solution recirculation plate and has an elongated rectangular opening 450 for circulating solution from chamber 413 to pump chamber 442. Opening 452 is positioned to align with opening 444 of plate 432.

Plate 428 (Fig. 26D) serves as a separator between positive and negative pressure and is provided with openings 454, 456 and 458 arranged to communicate with opening 450 in plate 430. Plate 428 is also provided with an opening 460 arranged to align with opening 452 of plate 430.

Plate 426 (Fig. 26C) is provided with a horseshoe-shaped opening 462 communicating with opening 460 in plate 428 and is provided with openings 463, 464 and 466 aligned with openings 454, 456 and 458 of plate 428, respectively.

Plate 424 (Fig. 268) includes a manifold having solution return ports 468, 470 and 472 aligned with ports 463, 464 and 466 of plate 426. Plate 424 has a plurality of uniformly sized ports 474 (two for each bearing) arranged in a horseshoe shape in alignment with ports in the ends of bearings 438 to distribute solution to the ends of the bearings from ports 462 in plate 426.

Plate 422 (Fig. 26A) is nearly identical to plate 424 and is provided with openings 476, 478 and 480 which are aligned with openings 468, 470 and 472 of plate 424, respectively. Plate 422 is also provided with a plurality of openings 482 (two for each bearing) which are aligned with openings 474 of plate 424, but are slightly smaller than them to gradually reduce the cross-section of fluid flow into bearings 438. The bearings 438 are secured to plate 422 such that the bearing ends are welded to the surface of plate 422 around openings 482 so that openings 482 only communicate with the interior portions of the bearings.

During operation of the fluid distribution system, pump 418 pumps fluid from chamber 446 through openings 444, 452 and 460 of plates 432, 430 and 428, respectively, into distribution opening 462 of plate 426. From opening 462 of plate 426, solution is distributed through openings 474 and 482 of plates 424 and plate 422, respectively, to the interior of hydrostatic bearings 438.

Fluid is discharged from the bearings 438 into the tank 412 as described below. The discharged solution is then discharged from the tank 412 via openings 476, 478 and 480 in the plate 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 to the features of the hydrostatic bearings 438, and in particular to Figs. 23, 29, 30 and 31 of the drawings, each bearing comprises two identical, elongated, correctly positioned assemblies 490a and 490b (Figs. 30 and 31) spaced apart to allow the passage of a photosensitive web material W in continuous or sheet form. Each assembly forms 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 attached to flanges 492a and 492b, respectively, which in turn are provided with a plurality of spaced-apart openings 494a and 494b, respectively, for discharging fluid from the interior of the channels to the area outside of these flanges. A second pair of flanges 496a and 496b are attached to the flanges 492a and 492b, respectively, and are each provided with a plurality of rectangular openings 498a and 498b, respectively, which receive solution from the openings 494a and 494b, respectively, to form regions of pressurized solution on both sides of the sheet material W.

The pairs of correctly positioned assemblies are closely spaced from each other, forming a small gap between the sides of the flanges 496a and 496b for the passage of the sheet material W, as can be seen most clearly in Fig. 30. For a sheet material having a thickness of 0.178 mm, the gap is approximately 1.27 mm. This gap is achieved by arranging spacers (Fig. 31) between the two assemblies on each side. The complete bearings are then the plate 422 with the open ends of the channels 490a and 490b aligned with two openings 482. The other ends of the channels 490a and 490b are secured together and are sealed by an end cap 501 (Fig. 23) to restrict the discharge of solution to the openings 494. The attachment of one end of the bearing 438 to the plate 420 and the attachment of the end cap 501 forms a rigid bearing structure.

The bearings are preferably sized to form fluid path lengths within the bearing such that solution is discharged into the tank when the fluid boundary layer reaches a predetermined thickness. This criterion was previously described in connection with the embodiments of Figs. 1-8. The piping system is preferably structured to achieve a fluid pressure of 50.8 to 152.4 mm H2O in each of the rectangular openings 498a and 498b. With this arrangement, a fluid pad is located on each side of the sheet material within each bearing to effect smooth transport of the sheet material without contacting the bearing surfaces.

In the relatively straight portions of the web path, the correctly positioned sides of the flanges 496a and 496b are flat, as shown in Figs. 30 and 31 and detailed in Fig. 32A. In the curved portions of the web path, the correctly positioned sides of the flanges 496a and 496b are curved to form a curved web path therebetween. In these weaving portions, a flange 496 is provided with a concave surface 500, as shown in Fig. 32C. The opposite flange 496 is provided with a complementary convex surface 502, as shown in Fig. 32B. The The curved path of the web-like material thus formed is evident from the consideration of the lower four bearings in Fig. 29.

A bridging means is provided between adjacent bearings 438 to ensure that the leading edge of the sheet material exiting one bearing is properly guided into the next bearing in the path of the sheet material. Referring to Figure 29 of the drawings, an arched bridging means 504 is disposed between adjacent bearings. Flanges 506 and 508 of the means 504 are secured to the flanges 492 of the adjacent bearings 438 to bring the surface 510 of the means 504 into adjacent relationship with the surface of the flanges 496b. The surface 510 thus forms a bridge between the gaps of the adjacent bearings.

In Fig. 29, the bearings 439 are shown as a curved film path. However, different path configurations can of course be used, so that the configuration shown here is only to be understood as an example.

When the web material being processed is in sheet form, such as X-ray sheet film, the film path formed by the hydrostatic bearings 438 is shorter than the length of the film sheets so that roller means at the entrance and exit of the path can transport the sheets to and from the path without losing a sheet. In such a sheet film processor, two rollers 520 are arranged at the entrance and exit of the tank chamber as shown in Fig. 23. When there is a series of processing chambers, two rollers 520 may be arranged between adjacent tanks as shown in Fig. 25. In such a case, the film guides 522 would be provided to facilitate transport between adjacent chambers.

If the material being processed is a continuous web, such as 35mm films glued together, roller means, such as rollers 520, may be provided only at the entrance to the web path, these rollers being sufficient to transport the film through the bearings supported by the liquid pads. In this case, the rollers 520 between adjacent chambers are not required, and the rollers 520 at the entrance to the first chamber may be used to transport the web through the entire system.

Figures 23 and 29 of the drawings show an arrangement of the hydrostatic bearings for a processor having a single chamber. In this case, the bearings 438 would be arranged in a simple huffom. However, if multiple chambers are present, the bearings would preferably be arranged in the garland configuration shown in Figure 33 so that the web or sheet exits each chamber along a gently curved film path.

In the case of sheet or continuous web materials, it may be desirable to place rollers between chambers of a multi-chamber process to provide a doctoring action to remove liquid from the material before it enters the next chamber.

The advantages of the processor described are now obvious. The fluid cushions formed in the rectangular openings and adjacent areas effectively support the web-shaped material and enable it to be transported through the processing solution. In addition, the System constantly supplies the sheet material with circulating fluid that discharges from the bearings to prevent fluid stagnation. Thus, the bearings not only support the sheet material, but also create a more efficient treatment process.

With respect to each bearing, fluid is supplied from the central region of the bearing and discharged from the sides. This arrangement creates fluid discharge flows on both sides of the sheet material, both at the entrance and exit of the bearing, preventing the sheet material from lifting and coming into contact with the bearing surfaces.

Claims (6)

1. Device for treating a web-shaped material (F) with a liquid, with means that form a narrow, elongated channel (13) for receiving and treating the web-shaped material (F), characterized in that - the means comprise a plurality of elongate inlet openings (34, 36) spaced apart along the channel for introducing treatment liquid into the channel, and that the means comprise at least one elongate outlet opening (38, 42; 40, 44) associated with each of the inlet openings for removing treatment liquid from the channel, the openings extending transversely to the channel, and that - means are provided which feed treatment liquid into the inlet openings (34, 36) at high speed, with a pressure which is so great that a liquid cushion is formed between the means forming the channel and the web-shaped material, and which is so low that the laminar flow of liquid from the inlet openings to the outlet openings (38, 42; 40, 44) associated therewith is interrupted, the outlet openings being arranged at a predetermined distance (L) from their associated inlet openings in order to effect removal of the treatment liquid from the channel when the edge layer of the liquid reaches a predetermined thickness and to limit the increase in the thickness of the treatment liquid along the channel and the subsequent decrease in the chemical transfer rate or the heat transfer rate. 2. Device according to claim 1, characterized in that the treatment liquid consists of one or more treatment chemicals and that the distance (L) between the individual inlet openings (34, 36) and the outlet openings (38, 42; 40, 44) associated with them is so large that the chemical mass transfer rate H of each treatment chemical in the high-velocity liquid flow is expressed by the following formula: H = 1.467 [D²u∞/Ly 1/3 where - D is the chemical diffusivity of the respective treatment chemical in cm²/sec, - u∞ is the velocity of the flow parallel to the web-shaped material (F) and has a value in the range of about 20 to about 100 cm/sec, - L is the predetermined distance and has a value in the range of about 0.25 to about 2.5 cm, and - y is the distance from the web-shaped material (F) and has a value in the range of about 0.05 to about 0.10 cm. 3. Device according to claim 1 or 2, characterized in that the treatment liquid consists of one or more treatment chemicals and the distance (L) between the individual inlet openings (34, 36) and the outlet openings (38, 42; 40, 44) assigned to them is so large that the chemical mass transfer rate H of the liquid in the high-speed liquid flow is about 0.01 to about 0.001 cm/sec. 4. Device according to claim 1, characterized in that the distance is about 0.25 to about 2.5 cm. 5. Device according to claim 4, characterized in that the laminar liquid flow in a direction parallel to the web-shaped material is about 20 to about 100 cm/sec. 6. Device according to claim 1, characterized in that the distance (L) is so large that the liquid is removed when the boundary layer of the liquid has a predetermined thickness in order to maintain an energy transfer rate in the liquid which exceeds the energy transfer rate of the web-shaped material.