1994-05-26
1995-12-12
Rutledge, D.
354330, G03D 308
Patent
active
054754615
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to photographic processing apparatus and is more particularly concerned with the processing of small areas of photographic material, for example, prints on photographic paper.
It is well-known to use rotating drums in photographic processing apparatus. U.S. Pat. No. 4,613,223 discloses an arrangement in which a flexible sheet of photographic material is driven along an endless curved path within a processing tank by passing the sheet through nips formed between at least one pair of driven rollers. At least one of the driven rollers is the drum itself. During processing, the emulsion (sensitive) surface of the sheet is arranged not to come into contact with any stationary part of the processing vessel as it is being processed. This prevents damage to the surface during processing. After driving the sheet around the endless path for a predetermined number of cycles, which defines the processing time, the sheet is then directed out of the processing tank.
The arrangement described above, has the disadvantage that little or no agitation is applied to the emulsion surface of the photographic material being processed. This may result in uneven processing of the material and variable sensitometry.
Furthermore, relatively large volumes of processing solution are required which makes the arrangement disclosed unsuitable for unstable processing chemistry and single use chemistry as large volumes of processing solutions need to be discarded on a regular basis.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide photographic processing apparatus which overcomes the problems mentioned above.
According to one aspect of the present invention, there is provided photographic processing apparatus including at least ode processing stage, each processing stage comprising: tank, the clearance between the vessel and the drum being substantially constant; and which is arranged to direct photographic material into and through the tank during processing, the rollers being driven at a rate to ensure that processing is achieved as the material passes through the processing tank; independently of the speed of the drive rollers.
By this arrangement, only low volumes of processing solution are required allowing unstable and single use processing chemistry to be used.
Preferably, the clearance between the drum and the interior surface of the processing tank is less than 5 mm, and most preferably, less than 2 mm.
BRIEF DESCRIPTION OF THE DRAWING
For a better understanding of the present invention, reference will now be made, by way of example only, to the accompanying drawing, the single FIGURE of which is a Schematic illustration of processing apparatus constructed in accordance with the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The arrangement to be described may be the only processing stage of a photographic processor, or it may form one of several similar stages.
In the Figure, a generally U-shaped processing tank 10 is shown. A central rotatable drum 20 is mounted in the tank 10 with a clearance between interior surface 12 of the tank 10 and the drum 20 of approximately 1 mm. Processing solution 30 is held in the tank 10 at the level shown. Two pairs of rollers 40, 42 and 44, 46 are respectively positioned at the inlet 14 and the outlet 16 of the tank 10. Photographic material is fed into the tank 10 by one pair of rollers 40, 42, at the inlet, passes around half of the drum 20 and then out of the tank 10 and through the other pair of rollers 44, 46. Rollers 44, 46 may be squeegee rollers to remove excess processing solution from the material before it passes to the next stage of the apparatus.
Rollers 40, 42, drive the material 50, for example, photographic paper, through the processing tank 10 at a rate to ensure that processing is completed in the time that the material 50 passes through inlet rollers 40, 42, through the tank 10 and out through outlet rollers 44, 46. The time during which the material is processed is det
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patent: 3368526 (1968-02-01), Matsumoto et al.
patent: 3690758 (1972-09-01), Knechtel et al.
patent: 4003070 (1977-01-01), Merz et al.
patent: 4613223 (1986-09-01), Cherry et al.
Patent Abstracts of Japan, vol. 13, No. 73, Feb. 20, 1989
Patent Abstracts of Japan, vol. 6, No. 41, Mar. 13, 1982.
Fyson John R.
Glover Edward C. T. S.
Eastman Kodak Company
Rutledge D.
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