US3438140A

US3438140A - Drier for photographic layer supports in sheet form

Info

Publication number: US3438140A
Application number: US566691A
Authority: US
Inventors: Roland Koehler; Rudolf Birk; Hans Dieter Frick; Harald Fengler; Erwin Geyken
Original assignee: Agfa Gevaert NV
Current assignee: Agfa Gevaert NV
Priority date: 1965-07-20
Filing date: 1966-07-20
Publication date: 1969-04-15
Anticipated expiration: 1986-04-15
Also published as: DE1497394A1; GB1157281A; BE684359A; US3435539A; FR1560219A; NL6610172A

Description

April 1969 R. KOEHLER ETAL 3,438,140

DRIER FOR PHOTOGHAPHIC LAYER SUPPORTS IN SHEET FORM Filed July 20, 1966 F/GZ FIG]

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ATTORNEY United States Patent U.S. Cl. 34-160 5 Claims ABSTRACT OF THE DISCLOSURE A drying apparatus for photographic sheet material, especially film, of the general type in which the sheet material is transported along a given path by co-operating pairs of guide rollers arranged in spaced parallel relation along such path, the sheet material being guided by the roller pairs being contacted by air streams issuing from blower tubes arranged on either side thereof between adjacent pairs of rollers, each of the blower tubes when viewed in cross-section having flattened side walls extending generally normally to the support path, an inside end wall adjacent said support path which is inclined relative to said path, and an outside end wall remote from said path extending between the remote ends of said flattened side walls to complete the tube, said inclined inside wall having a slit-like air passage extending lengthwise therein, whereby a current of air emerging from said passage flows parallel to said inclined wall and upon passing the limit of said wall generally parallel to the support path. Preferably the remote end wall of each tube is of semicylindrical configuration and the inclined end wall faces in the direction of movement of the sheet material through the apparatus. The air passage in each tube is preferably located at a point in the inclined end wall closer the shorter of the two flattened side walls.

This invention relates to a drier for photographic layer supports in sheet form, especially sheet film.

Such driers are known with a series of transport rollers arranged on both sides of the path of the layer support, blower tubes being arranged between the rollers to blow onto the layer support dry air which enters the tubes from their ends at both sides.

In known arrangements of this type, the blower tubes direct streams of air extending over the whole width of the layer support substantially normal to said layer support. These constructions have the disadvantage that even if the air streams from two opposed tubes do not precisely cancel each other out as regards their efl ect on the layer support, satisfactory passage of the leading edge of the layer support is not ensured. It is often the case that the leading edge of the layer support becomes deflected and does not reach the next guide roller in the correct position.

The present invention provides a drier for photographic layer supports in sheet form, especially sheet film, said drier having a succession of transport rollers for the layer supports, arranged on both sides of the path of the supports, and between the rollers, in the transport direction, blower tubes for directing air onto the supports, the said tubes having a cross section so deviating from the circular, and having exit apertures for the air so arranged in a tube surface inclined with respect to the path of the supports, that after exit from said surface the air passes along it and, when it becomes clear of said surface, flows in a direction tangential or approximately tangential to the layer supports.

By means of this tangential guiding of the air flow, the possibility of the leading edge of the layer support being deflected to any great extent from its path is practically excluded.

In one embodiment of the invention the blower tubes are of near trapezium shaped cross section, the parallel sides of the trapezium being arranged perpendicular to the path of the layer supports, the rear side with respect to said path being of cylindrical curvature and the side' facing said path being inclined thereto at an angle in a range close to 45, an exit aperture in the tube being in the latter surface at a point nearer to the shorter than to the longer parallel side. With a blower tube of this type, experiments have shown that the flow of air is particularly closely tangential to the layer supports.

Preferably the exit aperture in a tube is in the form of a slit extending over a distance corresponding to the relevant dimension of the largest layer support to be dried in the drier. This construction allows the use of a simple manufacturing method, namely the milling of the slit, and ensures a sufliciently even distribution of air over the whole width of the layer support.

An arrangement is to be preferred in which in the case of a trapezium shaped tube cross section, the tubes are arranged with their longer parallel side facing the direction of approach of the layer supports. The tangential flow is then in the opposite direction to the layer supports passing through. A counter flow is thus produced which is particularly advantageous for drying, and since there is a higher relative speed of layer support to air stream, lower drying temperatures can be used than with conventional arrangements, whilst maintaining the same drying time.

The invention is illustrated by way of example in the accompanying drawing, in which:

FIG. 1 is a diagrammatic sectional elevation of a drier according to the invention, and

FIG. 2 is a cross-section of a blower tube of the drier of FIG. 1.

Referring to FIG. 1 of the drawing, in a fixed airtight housing 1 are supported a large number of pairs of transport rollers 2, 3 which are driven by conventional drive, not illustrated, e.g. by way of bevel gears. The rollers are supported in frames 4 which can be inserted into corresponding recesses 5a in partitions 5 which are normal to the roller axis and of which only one is visible in the drawing. In order not to damage the photographic layer, which is extremely sensitive in the damp state, the rollers are made of butyl rubber, polyethylene, hardened paper or the like.

The drier is intended to be fed with the photographic layer supports to be dried, at an opening 1a in the housing, either by hand or automatically from a known type of continuous developing device in the case of sheet film. The sheet film, for example, passes downwards in the drier. This construction is of advantage, but the drier could be adapted for horizontal passage of the sheet film.

In a vertical portion of the drier, constituting a drying chamber, between each pair of rollers and the next pair, a pair of

blower tubes

6, 7 is arranged, one on each side of the path of the sheets and spaced from said path. The shape of the blower tubes and the direction of the air stream therefrom are described below with reference to FIG. 2 of the drawing.

The

blower tubes

6, 7 are mounted in the partitions 5. One partition 5 is part of an air supply channel of large cross-section, into which air is blown by a blower 8 through a pipe 9. The blower 8 i mounted in a housing 10 which is attached to the housing 1. Between the housing 1 and the housing 10 there is an air passage 11, through which air can be aspirated from the drying chamber by the blower 8. In addition, the chamber 10 also has an opening 10a, so that fresh air can also be aspirated into it. From the pipe 9, a further pipe 12 branches off, which leads a proportion of the air conveyed by the blower 8 to the exterior. The drier is therefore an air circulating drier to which a certain proportion of fresh air is fed and from which a corresponding quantity of moist air is discharged.

Laterally of the rollers 2, 3 and the blower tubes 6, 7 a perforated partition 13 is arranged which provides a separate suction channel in the housing 1. Air which has emerged from the

blower tubes

6, 7, after contact with the film sheet, passes through holes in the partition 13 into the suction channel and through the passage 11 to the blower 8. A heater is preferably provided in the entry to the housing 10.

Beneath the lowest pair of rollers 2', 3 is arranged a slot 14 in the base of the housing 1, through which slot completely dried film sheets can fall into a receiver 15. This is accessible through an opening 16 in a front wall of the houing 1, so that the film sheets can be removed at that point.

Referring now to FIG. 2, a blower tube is seen to have a cross-section of near trapezium shape, the parallel sides 6a, 6b of which, perpendicular to the path of the layer supports, are approximately twice as long as the smaller transverse dimension of the tube. One narrow side 60! is inclined at about 45 with respect to the parallel surfaces and the other 60 is of cylindrical curvature. Resulting from the manufacturing method (extrusion), and to be preferred for improved guiding of the film sheets, all corners are rounded, particularly at the points facing towards the film sheet path. The blower tubes are preferably made of aluminium, which can easily be given the required shape by the extrusion method.

In the said inclined surface 6d, at a point nearer to the shorter than to the longer parallel side, there is milled an exit slit 6e. Experiments have shown that with this type of cross-section when there is excess pressure within the tube a stream of air is produced which, as shown by the arrow in FIG. 2, on emergence first flows in a direction tangential to the inclined surface 6d and when clear of the tube surface moves in a plane normal to the two parallel surfaces 6a, 6b, i.e. tangential or approximately tangential to the path of the film sheets.

The transport rollers need not be arranged opposite each other in pairs as shown, but alternately on the two sides of the path of the film sheet, A blower tube can then be arranged opposite a transport roller in each case. The blower tubes can, instead, be positioned to direct the air stream in the direction of travel of the film sheet, so that drying takes place with the air flow and the film sheet moving in the same direction. This arrangement has a rather poorer drying eflect compared with the counterflow method, but results in better guiding of the leading edge of the film sheet.

Furthermore, there may be used drier tubes of similar cross-section in which an air flow emerging from apertures is directed along a surface which is inclined at an angle of less than 60 to the direction of the outlet aperture and then is deflected into a more or less tangential direction to the articles being dried.

We claim:

1. Drier for photographic layer supports in sheet form, especially sheet film, comprising a series of rollers for transporting said supports along a predetermined path, said rollers being arranged in spaced parallel relation along both sides of said path; and a series of blower tubes for directing air upon said supports, said tubes being disposed in spaced parallel relation to said rollers, one between each adjacent pair of such rollers; each of said tubes when viewed in cross-section having flattened side walls extending generally normally to the support path, an inside end wall adjacent said support path which is inclined relative to said path, and an outside end wall remote from said path extending between the remote ends of said flattened side walls to complete the tube, said inclined inside wall having a slit-like air passage extending lengthwise therein the axis of the passage being at an acute angle to said outer surface of said inclined wall whereby a current of air emerging from said passage flows parallel to said inclined wall and upon passing the limit of said wall generally parallel to the support path.

2. Drier according to claim 1, wherein the blower tubes are of generally trapezoid shaped cross section with the two parallel sides of the trapezoid being arranged perpendicular to the path of the layer supports, the side between said parallel sides remote from said path being of approximately cylindrical curvature and the side bet-ween said parallel sides adjacent said path being inclined thereto; said air passage being in the latter side at a point nearer to the shorter of the two parallel sides.

3. Drier according to claim 2, wherein said side adjacent said path is inclined thereto at an angle in a range close to 45.

4. Drier according to claim 1, wherein said slit-like air passage extends at least over a distance equal to the corresponding dimension of the largest layer support to be dried in the drier.

5. Drier according to claim 1, wherein said inclined wall is inclined outwardly and forwardly with respect to the path of the supports.

References Cited UNITED STATES PATENTS 2,229,921 1/1941 Golf et a1. 34-23 XR 3,147,090 9/1964 Russell et al 34-160 3,316,657 5/1967 Haywood 341 16 XR FOREIGN PATENTS 218,770 2/ 1910 Germany. 612,366 4/1935 Germany.

H FREDERICK L. MATTESON, JR., Primary Examiner.

H. B. RAMEY, Assistant Examiner.