US3434225A - Drier for film processors - Google Patents

Description

March 25, 1969 E. M. KNIBIEHLY DRIER FOR FILM PROCESSORS Sheet Filed Sept. 5, 1967 INVENTOR Earle M. Knibiehly ATTORNEYS March 25, 1969 E. M. KNIBIEHLY DRIER FOR FILM PROCESSORS SheetLof? Filed Sept.

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INVENTOR Earle M. Knibieh ly ATTORNEYS United States Patent U.S. Cl. 34160 8 Claims ABSTRACT OF THE DISCLOSURE A plurality of rollers adapted to transport film through a processor drying zone are associated with bafiies defining an air inlet and an air exhaust located between each adjacent pair of rollers and extending respectively to air inlet and exhaust plenums. The bafiles are so oriented relative to the rollers that, when a sheet of film is in engagement with the rollers, an air flow pocket is formed adjacent the film causing air fiow turbulence extending over a limited region of the film between a pair of adjacent rollers, and the partially saturated air is then quickly exhausted without recirculation over other sections of the film.

Background of the invention The present invention is concerned with driers for use in various drying applications, and is more particularly concerned with an improved drying section for use in film processors, e.g., of the graphic arts types, wherein relatively large sheets of film, such as continuous tone emulsion film, must be dried.

It is well known that continuous film processors may incorporate a drying section therein adapted to dry the film after it has otherwise been processed. Various arrangements adapted to introduce or blow air over the film have been suggested in the past. For the most part, these prior arrangements have been so constructed that air flows from a main inlet port over the film, passing then to an appropriate exhaust port; and the air flow arrangements have been such that the air, during its flow between the inlet and exhaust ports, attempts to dry relatively large sections of the film. As the drying process continues, the relatively dry, warm inlet air absorbs moisture and becomes partially saturated; and in prior systems, this partially saturated air is often caused to impinge on relatively large areas of the film before being exhausted. The drying process, in these prior systems, is therefore relatively inefficient.

Prior arrangements have also often been so constructed that air passing toward the film tends to impinge on the film in relatively smooth flow, rather than turbulent flow. In this respect, it should be noted that the efficiency of any drying process does not depend upon the amount of air which may be caused to flow between a main inlet and an exhaust, but is actually determined by the amount of air which impinges upon any particular section of film, the characteristics of air flow at the region of film impingement, and the disposition which is then made of partially saturated air in the system. The present invention, taking all of these factors into consideration, assures that relatively small increments of film are exposed to intense turbulent air flows, with the partially saturated air resulting from film drying then being quickly removed from the entire system without circulation over other film sections.

Summary of the invention In accordance with the present invention, an improved drying section is provided wherein turbulent air flow is imposed upon a limited section of an object to be dried, with partially saturated air then being removed quickly,

3,434,225 Patented Mar. 25, 1969 and without recirculation. As will be apparent to those skilled in the art, driers of the type contemplated in the present invention can be used in various applications; but they find particular utility in the drying of continuous tone emulsion films. Such films have much thicker emulsion layers than other films, e.g., than lithographic films, and are accordingly much more difiicult to dry. The present invention achieves relatively rapid, highly eificient drying in these difiicult applications.

In accordance with the present invention, a drier is provided comprising a plurality of rollers adapted to transport a sheet of film along an essentially linear path through a drying zone. The rollers are arranged to engage opposing sides of the film sheet; and, between each pair of rollers, on both sides of the path of film travel, a series of bafiles, plates, or extrusions are provided defin ing a plurality of air inlets and outlets. The battle arrangement is such that both an air inlet and an air outlet is provided between each adjacent pair of rollers on each side of the path of film travel; and, as a result, air passing between a given inlet and its associated outlet is caused to impinge on one side only of a limited section of film extending between an adjacent pair of rollers on a given side of the path of film travel. By this arrangement, therefore, each increment of relatively warm and dry incoming air seeks to dry only a limited section of film; and increments of partially saturated air resulting from partial drying of said limited film sections are then quickly removed from the drier without recirculation over other sections of the film.

The arrangement of baflles, in association with the rollers and with a sheet of film being transported by said rollers, is moreover such that air passing from a given inlet to its associated outlet is caused to experience extreme turbulence. To this effect, a sheet of film engaging a given roller is arranged to form an air pocket exposed to incoming air; and the air impinging in this pocket becomes highly turbulent. This turbulent air, in passing from an inlet to its associated exhaust, causes far more efiicient drying than would be the case with laminar flow over a section of film.

The overall arrangement thus produces highly efiicient drying by concentrating air on successive separate sections of the film, by causing the air to exhibit turbulent flow over each of these separate sections, and by then quickly removing partially saturated air from the drier without recirculation.

Brief description 0 the drawings FIGURE 1 is a diagrammatic side View of a film processor incorporating an improved drying section of the type contemplated in the present invention;

FIGURE 2 is a diagrammatic detail view of a portion of the drying section, constructed in accordance with one embodiment of the present invention; and

FIGURE 3 is a diagrammatic detail view of a portion of the drying section constructed in accordance with another embodiment of the present invention.

Description of the preferred embodiments FIGURE 1 illustrates a film processor adapted to process relatively large sheets of film, such as: are employed in the graphic arts field. The overall processor is adapted to transport a sheet of exposed film along a path 10 through a plurality of processor sections including a developer tank 11, a fixer tank 12, and a pair of wash tanks 13 and 14. The tanks 11 through 14, and appropriate mechanisms for transporting film in succession from one to the next of these tanks, are in themselves well known to those skilled in the art.

In accordance with the present invention, a sheet of film, subsequent to its passage through the second wash tank 14, is caused to pass through a pair of squeegee rollers and said sheet is then conveyed, by a short conveyor illustrated diagrammatically at 16, to the inlet slot of a drying section 17. Drying section 17 comprises a plurality of rollers 18 adapted to engage one side of the film sheet, and a further plurality of rollers 19 adapted to engage the other side of said sheet. Rollers 18 and 19 are positively driven, in synchronism with one another, by appropriate motor means (not shown); and said driven rollers 18 and 19 have their axes mounted in parallel planes respectively, to move the sheet through drying section 17 along an inclined path (inclined, for example, at approximately 30 to the horizontal) to an exit slot 20. The dried sheets are then collected in an appropriate bin 21. Rollers 18 and 19 are mounted on centers so positioned relative to the nominally linear path of travel of the film sheet through the drier, as to very slightly overlap the linear path of travel on both sides of said path, whereby the film sheet actually exhibits a slightly serpentine configuration (exaggerated in FIGURES 2 and 3) as it passes from one to the next roller on opposing sides, respectively, of the path of travel. The amount of interference is determined by the characteristics of the sheet being processed, specifically the base thickness of the film (3-8 mils), and is appropriately selected to assure positive transport of the film through drying section 17, without scratching the film surface.

Drying section 17 comprises a relatively large housing 22 having inclined perforated metallic barriers 23 and 24 on its interior located on opposing sides of the rollers 18 and 19 to define a pair of equalizing pressure plenums 25 and 26 located, respectively, on opposing sides of the path of film travel through the drier. Plenums 25 and 26 are associated with blowers 27 and 28 respectively adapted to achieve a selected static air pressure in said plenums.

Resistance heaters 29 and 30 are disposed adjacent the perforated metallic sheets 23 and 24 for heating dry air passing through said sheets 23 and 24 from plenums 25 and 26 thereby to produce dry, warm air (preferably having a temperature less than 130 F. to assist in maintaining dimensional stability of the film) on the downstream sides of perforated sheets 23 and 24. As an alternative to heaters 29 and 30, appropriate inlet dehumidifiers may be provided, for supplying dry air at room temperatures (e.g., about 75 F.). When such a dehumidification system is employed, it is desirable to supply air haivng a greater moisture content at the entrance to the drier section than at locations farther downsream in the path of film travel to avoid glazing the emulsion surface at the beginning of the drying process, which glazing would tend to trap internal moisture in the emulsion.

A plurality of bafi les 31 are positioned adjacent rollers 18 between the path of travel of the film sheet and perforated barrier 23; and a further plurality of baffles 32 are located between rollers 19, between the path of travel of the film sheet and perforated barrier 24. These bafiles define an air inlet and an air exhaust between each pair of rollers, on each side of the path of film travel, whereby air passing from equalizing pressure plenums 25 and 26 is caused to impinge in a large plurality of separate flows on limited sections of both sides of the film being dried. Two possible arrangements for these bafiies are shown diagrammatically in FIGURES 2 and 3 respectively.

Referring initially to FIGURE 2, it will be seen that the baffles may take the form of extrusions or other metallic constructions having cross-sectional configurations of the types illustrated in FIGURE 2 and adapted to provide a plurality of inlet ducts 40, communicating respectively with plenum 25, and leading respectively to a plurality of relatively small inlet orifices 42. The battles further define a plurality of exhaust orifices 43 each of which communicates with an exhaust duct 44 isolated from equalizing pressure plenum 25 (and from inlets 40, 42) by means of solid walls 45. A similar arrangement of inlet and exhaust facilities 15 disposed between each pair of adjacent rollers on each side of the path of film travel 46, whereby increments of air from plenum 25 are caused to be introduced and then exhausted between each adjacent pair of rollers, on each side of the path of film travel. Thus, the battles associated with rollers 19 define a plurality of inlet ducts 40a, communicating with plenum 26; and further define a plurality of inlet orifices 42a, as well as plurality of exhaust ducts 44a. The several exhaust ducts 44 on one side of the path of film travel are connected together to a common exhaust isolated from plenum 25; and the several exhaust ducts 44a associated with rollers 19 on the other side of the path of film travel, are similarly interconnected to another exhaust isolated from plenum 26. The exhausts are preferably vented to a region or facility well isolated from that utilized to provide the inlet air to plenums 25 and 26.

Plenums 25 and 26 are maintained at a static pressure which has been arbitrarily designated P Air from the plenums 25 and 26 passes to inlet ducts 40 and 40a at a lesser pressure P and then passes through inlet orifices 42 and 42a, and is throttled to a still lesser pressure P In passing through restricted orifices 42, the air is caused to flow at increased velocity between a pair of adjacent rollers, e.g., the pair 18a and 18b. The air then exhausts through relatively large exhaust orifice 43 to exhaust duct 44 which is maintained at the lowest pressure P Exhaust orifice 43 is approximately three times the size of inlet orifice 42. to assure free flow of air between inlet duct 40 and exhaust duct 44.

When no film is passing between the rollers 18 and 19, air can pass between inlet ducts on one side of the path of travel, and exhaust ducts on the opposing side of the path of travel, e.g., along the paths marked 50, past the roller designated 19b. Air thus flows relatively smoothly across the normal film travel path 46. When a sheet of film is caused to enter the system, however, the film engages the rollers 18 and 19 so as to form air pockets which disrupt the normal cross flow paths. More particularly, in an arrangement shown in FIGURE 2, it has been assumed that a sheet of film designated 46a is in engagement with the rollers 18a, 19a, and 18b. Air flowing from inlet 42 is directed by inclined surface 51 of the baffle arrangement toward a pocket 52 caused by engagement of film 46a and roller 18b; and the air accordingly now experiences turbulence adjacent the side of film 46a between rollers 18a and 18b. This turbulent fiow absorbs moisture from that side of film 46a, and the partially saturated air is then immediately exhausted through duct 44 without recirculation to any other part of the drying system. It will be appreciated, of course, that this same action occurs between each adjacent pair of rollers, and that it occurs, moreover, on both sides of the film.

In a typical embodiment of the invention, the several rollers 18 and 19 may have a diameter of 1 /2 inches, with said rollers being mounted on Z-inch centers. The rollers 18 and 19 are, moreover, disposed in staggered relation to one another on opposing sides of the path of film travel. As a result of this overall arrangement, therefore, the leading edge of any entering sheet of film re mains unsupported for only a relatively small distance as it passes from roller to roller. The relatively short unsupported leading edge which can thus be present has sufiicient rigidity to avoid significant deflections due to any cross flow air 50 which the leading edge may engage as the film moves through the dried section. Since the cross flow which may occur involves equal and opposite flow velocities in both directions, there will be no significant resultant air force, and no significant turbulence in the region adjacent the lead-ing edge of the film.

In the arrangement of FIGURE 2, the path of air flow from a given inlet to its adjacent exhaust, along any one section of the film being dried, is essentially in the same direction as the path of film travel 46, i.e., each air inlet is upstream of its associated exhaust relative to the path of film travel. The relative positions of the inlets and exhausts can, however, be reversed so as to cause the air to flow in a direction counter to that of the path of film travel. An alternative arrangement of this type is shown in FIGURE 3.

The modified drying section of FIGURE 3 again employs a plurality of rollers 18 and 19, and a plurality of bafiies designated 60 and 61 on opposing sides of the path of film travel 46. The baffles 60 define inlet ducts 62 extending from plenum 2 5 to restricted orifices 63 positioned closely adjacent each of the rollers 18. A similar arrangement of inlet ducts and restricted orifices are provided adjacent rollers 19, as illustrated. The baffles, moreover, define exhaust ducts 64 and 64a which, it will be noted, are located upstream of their associated air inlets.

When no film is being transported through the drier, the path of flow can be a cross flow of the type designated by lines 65, with air flowing from an inlet duct 62 on one side of the path of travel to exhaust ducts 64a located on the other side of the path of travel. However, when a sheet of film is introduced into the system, and engages the rollers, pockets are formed between the film sheet and the rollers causing extreme turbulence of the air; and this turbulent air now passes in an upstream direction (relative to the path of film travel) to its associated exhaust duct.

Having thus described my invention, I claim:

1. A drier for photographic film comprising housing means defining a film inlet, a film outlet located in horizontally spaced relation to said film inlet at a position vertically below said film inlet, and a drying zone between said film inlet and film outlet, a plurality of spaced rollers mounted for rotation on coplanar axes in said drying zone for transporting photographic film to be dried through said zone along a linear, downwardly inclined path extending between said film inlet and outlet, means for driving said rollers in synchronism with one another, said rollers being located both above and below said linear path and being so positioned relative to said path that the outermost surfaces of said rollers slightly overlap said path on both sides of said path to effect positive transport of said photographic film along said path without scratching the film surface, baflie means in said zone positioned along both sides of said downwardly inclined path adjacent said rollers for defining air inlets and air outlets, said air inlets and outlets being disposed in groups each of which groups consists of at least one air inlet and at least one air outlet both disposed between an adjacent pair of said rollers on a given side of said linear path, supply means coupled to said air inlets for directing air through each of said air inlets into the space between the pair of spaced rollers associated with said air inlet and passing in said space along an air flow path directed toward the region of engagement between at least one of said pair of rollers and said film surface, and exhaust means coupled to said air outlets for removing air via each of said outlets from the space between the pair of spaced rollers associated with said outlet.

2. The drier of claim 1 wherein the rollers on one side of said downwardly inclined path are mounted in staggered relation to the rollers on the other side of said downwardly inclined path.

3. The drier of claim 1 including squeegee roller means located adjacent the film inlet of said housing means.

4. The drier of claim 1 wherein said linear path is downwardly inclined at an angle of substantially 30 to the horizintal.

5. The drier of claim 1 including heater means for heating the air supplied to said air inlets to a temperature greater than room temperature and less than 130 F.

6. A drier comprising housing means defining a drying zone, a plurality of spaced rollers mounted for rotation on coplanar axes in said drying zone for transporting an object to be dried through said zone, baflle means in said zone positioned adjacent said rollers for defining air inlets and air outlets, said inlets and outlets being disposed in groups each of which groups consists of a single inlet and a single outlet both disposed between an adjacent pair of said rollers, the inlet in each of said. groups being positioned upstream of the outlet in said group relative to the direction of travel of an object to be dried through said zone, said bafile means defining a plurality of said groups of inlets and outlets disposed respectively between a plurality of pairs of adjacent rollers, supply means coupled to said air inlets for directing air through each of said inlets into the region between the pair of spaced rollers associated with said inlet, and exhaust means coupled to said air outlets for removing air via each of said outlets from the region between the pair of spaced rollers as sociated with said outlet.

7. A drier comprising housing means defining a dn ing zone, a plurality of spaced rollers mounted for rotation on coplanar axes in said drying zone for transporting an object to be dried through said zone, bafile means in said Zone positioned adjacent said rollers for defining air inlets and air outlets, said inlets and outlets being disposed in groups each of which groups consists of a single inlet and a single outlet both disposed between an adjacent pair of said rollers, the inlet in each of said groups being positioned downstream of the outlet in said group relative to the direction of travel of an object to be dried through said zone, said bafile means defining a plurality of said groups of inlets and outlets disposed respectively between a plurality of pairs of adjacent rollers, supply means coupled to said air inlets for directing air through each of said inlets into the region between the pair of spaced rollers associated with said inlet, and exhaust means coupled to said air outlets for removing air via each of said outlets from the region between the pair of spaced rollers associated with said outlet.

8. A drier comprising housing means defining a drying zone, a plurality of spaced rollers mounted for rotation on coplanar axes in said drying zone for transporting an object to be dried throughsaid zone, bafile means in said zone positioned adjacent said rollers for defining air inlets and air outlets, said inlets and outlets being disposed in groups each of which groups consists of at least one inlet and at least one outlet both disposed between an adjacent pair of said rollers, each of said inlets being directed toward a pocket defined between one of said rollers and an object to be dried in engagement with said roller, whereby air passing from said inlet toward an object to be dried has turbulent flow adjacent an object to be dried when said object is in engagement with said roller, said bafile means defining a plurality of said groups of inlets and outlets disposed respectively between a plurality of pairs of adjacent rollers, supply means coupled to said air inlets for directing air through each of said inlets into the region between the air of spaced rollers associated with said inlet, and exhaust means coupled to said air outlets for removing air via each of said outlets from the region between the pair of spaced rollers associated with said outlet.

References Cited UNITED STATES PATENTS 2,640,277 6/ 1953 Dungler. 2,700,226 l/ 1955 Dungler 34-160 FOREIGN PATENTS 964,768 5/1957 Germany.

CARLTON R. CROYLE, Primary Examiner. ALLAN D. HERRMANN, Assistant Examiner.

US. Cl. X.R. 34-162

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