US3403455A - Film drying apparatus - Google Patents

Description

United States Patent "ice 3,403,455 FILM DRYING APPARATUS Robert J. Wilson, Rochester, N.Y., assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey Filed Mar. 2, 1967, Ser. No. 620,084 9 Claims. (Cl. 34-159) ABSTRACT OF THE DISCLOSURE A film drier wherein a single film strand within an easily threadable shallow channel moves past a plurality of oppositely disposed hot air jets developed in the shallow channel walls. By distributing the jets uniformly along both sides of the channels, high-speed, efficient, drying is accomplished without shoreline degradation or flutter damage of the film.

Background of the invention The present invention relates to driers and more particularly to high-speed driers suitable for drying continuous webs or strips.

In the art of high-speed drying of strips such as photographic filmstrips there are several problems which require unique solutions to effect a most satisfactory drier. One of the more popular prior art film driers has many coaxial conveyor rollers placed in a manner making it quite complicated to thread the film therethrough. A more acceptable design from a threading standpoint has hot air presented to only one side of the film. However, in such a system, the film tends to flutter when the drier is operated, particularly at the higher air flow rates necessary for high-speed drying. This, of course, raises a problem of film tension variation which, in an extreme case, such as a wet film momentarily sticking to another surface, can cause film breakage with resulting loss of time and material. Avoidance of destructive flutter can be accomplished by use of short lengths of film between closely spaced support rollers. However, certain driers with short film runs between turnaround rollers tend to develop shoreline residue damage. This damage effects a discoloration of the strip which occurs when the film is moved between two high-speed drying regions by means of a turn-around mechanism or a cross-over region. In the cross-over the drying is slowed considerably. Such alternate fast and slow drying periods tend to create drying ridges having a visible flaw pattern that resembles the patterns created by waves on a sandy shoreline.

Therefore, an object is to provide an improved highspeed filmstrip drying apparatus.

Summary of the invention In accordance with one embodiment of my invention a drier segment comprises a corrugated or fluted panel having a tortuous channel path on one side. Film support rollers are positioned at the corners of the path to convey a single web or strip of film through each of the straight channel sections. The single strip depth solves the prior art difficulty of threading the drier. Along the side walls of each of the channels are provided a plurality of opposed apertures or slots whereby heated air forced to fiow through the drier panel creates hot air jets. These balanced hot jets impinge on opposite sides of the filmstrip at a plurality of closely spaced locations. Impingement of air on opposite sides of the filmstrip does away with the flutter problem. Thus, long channels may be used without excessive tension problems, and the channel pattern of the drier may be arranged to fit almost any available space. The air flow pattern provides hot air 3,403,455 Patented Oct. 1, 1968 jets along the entire length of each channel section and throughout the region of turn-around roller and the crossover areas. This distribution of hot air jets throughout the tortuous channel path continuously maintains a high rate of drying so that shoreline damage is avoided.

The subject matter which is regarded as my invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, as to its organization and advantages thereof, will best be understood by reference to the following description taken in connection with the accompanying drawing, in which:

FIG. 1 is a block diagram of a conventional drier layout suitable for use with my invention;

FIG. 2 is a simplified perspective cut-away view of one conventional drier apparatus;

FIG. 3 is an enlarged plan view of a film segment illustrating the shoreline residue damage problem;

FIG. 4 illustrates a preferred embodiment of my invention;

FIG? 5 is a sectional view taken along the line 55 of FIG. 7;

FIG. 6 is a cut-away view taken along the line 6--6 of FIG. 5 and FIG. 7 is a view of another embodiment of my invention.

Referring now to the drawing, wherein like numbers indicate similar parts, I have shown in FIG. 1 a drier 10 which receives, through a drier input slot 12, a wet strip of material such as a 16 mm. or 35 mm. photographic filmstrip 11 from a processor. Air, indicated by the arrows 14, is pumped by a blower 15 through a heater 16 to pass through the drier 10 at a high-speed drying temperature such as F.

Certain inner parts of one of the conventional driers are indicated in the simplified perspective cut-away view of FIG. 2. The drier has a plurality of plenum chambers 20. The front chamber 20 is indicated in phantom lines to allow a clear showing of one of the several spiral paths of the filmstrip 11 during the period it is being hot air dried between the several plenum chambers 20. The filmstrip 11 is conveyed on a plurality of transport rollers 22 in a spiral path between each set of the plenum chambers 20 so that the emulsion side of the filmstrip (the outer side of the spiral) faces a plurality of hot air emitting slots 24 to be dried rapidly.

Placing of an additional'plenum chamber within the filmstrip spiral between the rollers 22 could obviously increase the number of air slots 24. However, such a more complex construction would seriously complicate thread ing of the filmstrip over the rollers. For instance, plenum chamber in the center of each spiral usually requires partial dismantling of the drier for threadup. Since the two plenums shown in FIG. 2 direct air toward only one (the emulsion) side of the filmstrip, flutter is a problem. Flutter is the motion of a long strip segment in response to air flow directed toward only one side thereof. The flutter problem is further aggravated by the flow of the air from the center of the spiral toward the end thereof. Thus, the end strands of the spiral are subjected to a lateral air flow as well as the direct impingement from the slots 24. The distance between the upper and lower rollers 22 is kept short to avoid damaging flutter. At such times as tension in the filmstrip is momentarily relaxed long spacing tends to allow the filmstrip to stick to itself and sometimes break. Additionally, it should be noted that there are no air slots provided in the region of the outer surface of the turnaround rollers 22 nor in the cross-over regions 25 where the filmstrip 11 moves from one spiral roller group to a next.

Referring now to FIG. 3, I have shown one of the results of a film damage which tends to occur during the rapid drying of filmstrips 11 in a conventional drier of the FIG. 2 construction. This film damage is known as shoreline wherein the filmstrip dries rapidly in a first region adjacent to an edge. Then the drying is slowed in a next region, whereby a visible line is created, several being indicated at 26. This slower drying of the filmstrip 11 often occurs when the filmstrip is moving through the crossover regions 25 where the air impingement on the filmstrip is greatly reduced, and may also occur when the film moves over the turn-around rollers 22.

Referring now to FIG. 4, I have shown an embodiment of my invention having a completely different type of film path from that in the drier of FIG. 2. In my drier the filmstrip 11 is not moved through a spiral pattern but is moved through a tortuous channel path formed in the surface of several panels 28 (by way of example, two panels being shown). As these channels are only about one filmstrip width deep, the filmstrip 11 may easily be threaded into a cross-over channel 29 and over one of the rotatably mounted transport rollers 22 into a much longer drying channel 31 to a second transport roller 22, etc. These channels are perforated or slotted to allow heated air to impinge on both sides of the filmstrip 11. Moreover, the path of the filmstrip 11 (indicated in phantom) is never outside of the channels 29 or 31 during the drying cycle. Thus, heated air continually impinges on and dries the filmstrip as it moves through the drier, whereby shoreline damage is greatly reduced or eliminated compared to prior art structures.

This air impingement is better illustrated by the detail shown in FIGS. 5 and 6 wherein a panel 28 is indicated in section with apertures shown as slots 35 opposed to one another (FIG. 5) so that air pressure on opposite sides of the filmstrip 11 (indicated in phantom) is equalized. With such balanced air pressure no damaging flutter is created. With no flutter problem, the channels 31 may be made as long as desired to fill any available drier space without any problem of excessive tension in the filmstrip.

In fact when long channels are used and fewer transport rollers 22 are required, a lower driving force may be used with a further reduction of film tension. Also, balanced air impingement will provide a cushion or lubricant to prevent the filmstrip being driven against and sticking to a wall surface of the long channel 31. Moreover, the filmstrip is not in a position to stick to itself as it could with a drier of the FIG. 2 construction. Thus, momentary sticking is prevented, and this cause of film breakage is eliminated.

FIGS. 5 and 6 also showv a portion of the open support frame, in the form of a strut member 38, to which the panel 28 is bolted. With air pumped toward one side of the panels 28, their many slots 35 operate to develop air jets directed toward the film in a manner more effective than the slots 24 of the plenum chambers in FIG. 2, because each slot is used for directing air to a single strand of film. Thus every slot may be of a simple design and yet most efiicient and effective size and design compared to the slots 24 which must supply air to several filmstrip sections.

FIG. 6 shows the slots 35 being substantially equally spaced throughout the length of the channel section. Similar spacing is provided throughout the outer surface of the short cross-over channels 29 as well as around the outer surface of the rollers 22. Additionally, at least one hot air slot is provided at a channel wall tip 39 between the rollers 22. Thus, drying of the filmstrip 11 is not materially slowed down even in the cross-over region of channel 29. The rollers of the FIG. 4 construction do not turn the filmstrip more than about 90", whereby less relative time elapses between hot air impingement drying periods even on the inner surface of the filmstrip. Finally, the rollers 22 may be made as small as hot (140 F.) film bending limitations will allow, because the roller size is Cir no longer the determinative element in the spacing between the filmstrips as compared to the FIG. 2 drier construction.

Because of the low tension needed to transport the film with no flutter and because of long unobstructed runs, it is not necessary to drive all of the rollers 22. In fact, some of the time it is not necessary to power all of the several driving rollers provided. Therefore, a tendency drive roller 40 is positioned to drive one of the transport rollers 22 in each of the panels 28, whenever the film strip is tensioned sufficiently to press the roller 22 against it. As several acceptable tendency or take-up drives are known, such as that shown in Patent 3,132,574 Ernisse issued May 12, 1964, it is not necessary to set forth such a one way drive mechanism in great detail here.

FIG. 4 also shows the left side of the left (input) panel 28 as having a bafile member or block 41 positioned against the apertures 35 of the half channel which does not contain any film. The use of such a block reduces the wasted hot air fiow through the panels 28. A similar block may be positioned inside the right hand panel 28 topre vent some of the air flow through the last half channel" 31 also. In the channel arrangement of FIG. 4 about 25% to 35% of the panel surface is taken up by the tortuous channel path (29, 31).

Referring now to FIG. 7 a somewhat more efficient space utilizing embodiment of my invention is illustrated wherein about of the surface of panel 28a is recessed in the form of channels. In this construction, the filmstrip 11 is moved through channels 29a and 31a of the panel 28a and six transport rollers 22 are provided instead of the four transport rollers of the panel 28. Again, the crossover and turn-around regions are provided with slots 35 both at the outer side of the film and at the inner tips 39. With filmstrips wherein shoreline is a particular problem care should be used to be sure that each of the trans port rollers 22 being driven by the tendency drive roll 40 receives the filmstrip 11 so that the emulsion coating is outermost. Thus, the emulsion surface will be continually bombarded by hot drying air from slots around the driven roller.

As may be apparent to those familiar with the drying art my invention makes it quite practicable to provide drying chambers that are longer and thinner than those of a more conventional design. However, since these drying chambers of my invention are easily made of light weight material, for instance, the panels 28 may simply be molded plastic and the rest of the drier box may be relatively light weight sheet metal or transparent plastic sheets, the overall thickness of the drier may be no more than two or three inches greater than the width of the filmstrip. Thus, for many filmstrips the drier need be no wider than about six or eight inches.

With this construction, it is feasible to hinge the driers so that they may easily be moved out of the way either during use or when out of use. One instance when such a foldaway hinged drier is of value is when several of these processors and driers are closely positioned side by side, and it is necessary to rethread one of the driers. Obviously, all of the ones to one side of the one being rethreaded could be folded so that the panel surface is exposed to provide substantially greater access than has been available for rethreading driers in the past. With a film take-up system mounted on the hinged drier, it is not even necessary to disturb the operation of any of the driers which are moved out of the way.

It should now be apparent that the drier of my invention is easy to thread, because it is only a single strip in' depth; that there is no flutter produced because of the balanced air jet impingement; and that there is no shoreline drying because of the ample and evenly spaced distribution of hot air slots 35 throughout the drying distance. Also, the panels may be easily set up in drier strips of 2, 3, 4 panels etc. depending on particular drying capacity requirements.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

I claim:

1. A drier for strip material including a blower situated to pump heated air and comprising:

a panel member having on one side a tortuous channel path consisting of curved portions and straight portions, the channel path being of a depth less than about two widths of the strip material so that a single strand of the strip material may be effectively dried therein; and

transport rollers located at each corner portion of the tortuous channel path for transporting the strip material within the channel path without its touching any channel wall surface, each channel wall being provided with a plurality of apertures for directing streams of drying air against the strip material at a plurality of locations throughout the tortuous channel path, the apertures being spaced substantially uniform distances apart throughout the tortuous channel path except where one of said rollers is located between a channel wall surface and the strip material, such uniform spacing providing substantially uniform drying of at least one side of the strip material to prevent shoreline damage thereto.

2. The invention of claim 1 wherein:

said plurality of apertures are opposed through relatively long straight channel paths to prevent flutter of the strip material between widely spaced transport rollers.

3. The invention of claim 1 wherein:

said tortuous channel path comprises at least about 30% of the surface of said panel member.

4. A high-speed, hot-air drier for a photographic filmstrip, wherein a blower moves air past a heater to supply hot air impingement at the filmstrip surface, comprising:

a panel member having a continuous and curved channel path on one surface thereof with hot air emitting slots spaced along both opposing walls of the channel path; and

transport rollers located at each corner of the channel path for transporting a single filmstrip within the channel and between the opposed hot air emitting slots, said slots extending around the outer side of the curves of the channel to cause hot air jets to impinge against the filmstrip on said rollers so that the drying rate of the filmstrip is maintained substantially constant to prevent shoreline damage.

5. In a drier for photographic filmstrip having an air heater, a blower for moving heated air from the heater to impinge on the strip to be dried, and means for moving the strip through the drier, the improvement comprising:

a thin wall panel member having one strip receiving channel of substantial U-shaped cross section, the sides of the U being of slightly deeper than the width of the strip and being spaced a distance substantially greater than the thickness of the strip;

said channel including curved and relatively straight portions arranged to form a tortuous path for the strip and having a plurality of spaced apertures in said sides along said path for directing heated air against the strip surfaces; and

transport rollers mounted for rotation in the curved portions of said channel for guiding the moving strip through the channel out of contact with the panel member.

6. An air drier for a moving strip, comprising:

a panel member defining one strip receiving channel having opposed side walls of a depth slightly greater than the width of the strip to be dried;

said channel including curved portions and being arranged to form a continuous tortuous path for the strip;

said side walls being spaced a distance substantially greater than the thickness of the strip and having therein a plurality of spaced apertures for directing drying air against the strip as it moves through the channel; and

transport means mounted for rotation in the curved portions of said channel for guiding the strip through the channel out of contact with said side walls, whereby uniformity in the drying of the moving strip is enhanced.

7. The invention of claim 6 and wherein;

the apertures in one side wall of the channel are positioned in substantially opposed relation to the apertures in the other side wall of the channel to thereby reduce flutter of the moving strip in the channel.

8. The invention of claim 6 and wherein;

said apertures are in the form of narrow slots which are positioned in substantially opposed relation in the side walls of the channel so as to direct streams of heated air onto the full width of the strip.

9. The invention of claim 6 and wherein;

the length of at least some straight portions of channel exceeds the length of curved portions, and a plurality of straight portions in said panel member are substantially parallel.

References Cited UNITED STATES PATENTS 2,932,902 4/1960 Copenhefer 34159 2,920,399 1/1960 Fry 34l59 3,263,345 8/1966 Fleisher et a1. 3459 KENNETH w. SPRAGUE, Primary Examiner.

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