1990-01-30
1992-08-18
Hix, L. T.
354319, 354323, 354324, G03D 1300, G03D 308
Patent
active
051403552
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a continuous developing apparatus for photographic films, in particular X-ray films.
BACKGROUND
An apparatus of this type is described in U.S. Pat. No. 4,023,190. In the latter, the papers and pieces of film to be developed are moved with only a quite slight deviation from a continuous conveying plane and due to the dynamic sealing of the processing chambers, at their inlet or outlet opening, a liquid level lying above the conveying plane can be maintained dynamically in the processing chamber, since the circulating pump associated with the processing chamber can supply slightly more processing liquid to the dynamically sealed processing chamber than is lost through the leakage points at the inlet opening and outlet opening.
However, if a developing apparatus of this type is stopped for a relatively long time, for example overnight or for the weekend, or if the apparatus is generally only required at intervals of several days, then when the circulating pump is switched off, on account of the leakage losses at the dynamic seals, the liquid level falls slowly to below the seals. Thus, the conveying means serving for moving the material to be developed are at least partially no longer covered with processing liquid and after the evaporation of water, developer salt or fixer salt remains on the conveying means. After the apparatus is once more set in operation, these salt crusts dissolve only slowly or on the whole no longer completely and then impede the troublefree conveyance and uniform processing of the material to be developed and may lead to scratches on the film.
Further developing apparatus with dynamically sealed processing chambers, filled with liquid, are described for example in U.S. Pat. No. 3,057,282, DE-OS 26 33 145, DE-OS 27 31 045 and DE-PS 33 45 084. For these developing apparatus, the above-described drawbacks are true to the same extent.
THE INVENTION GENERALLY
The present invention intends to develop a developing apparatus so that even with a relatively long stoppage of the apparatus, no salt crusts are formed on the conveying means, which serve for moving the material to be developed through the processing chambers.
This object is achieved according to the invention by a developing apparatus according to the following description.
In the developing apparatus according to the invention, a flood tank is additionally located below at least one processing chamber. In an operating position pre-set in the operating apparatus, the latter frees the inlet opening and the outlet opening of the associated processing chamber, so that in this case the same operating conditions exist as in the known developing apparatus described at the beginning, with the single difference that processing liquid overflowing from the processing chamber does not trickle back directly into the outer tank, on the contrary first of all passes into the flood tank and then overflows from the latter into the outer tank. However, as regards the liquid processing of the material to be developed, this difference is negligible.
In a raised operating position, which the flood tank assumes when the developing apparatus is switched off, the overflow edge of the flood tank lies above all the conveying means of the associated processing chamber. The conveying means are thus completely immersed in processing liquid, and thus no salt crusts may form thereon, even in the case of a very long stoppage of the developing apparatus. Since the flood tank is normally filled with processing liquid at the beginning of the lifting operation and at the time of lifting the flood tank, part of this liquid is displaced by the conveying means and the other parts of the processing chamber, reaching a sufficiently high liquid level is always guaranteed, even if the circulating pump is stopped at the beginning of the lifting operation.
Vertically movable outer tanks are already known per se in continuous developing apparatus. Thus, U.S. Pat. No. 3,624,728 discloses an automatic developing apparatus with a vertically movable
REFERENCES:
patent: 4023190 (1977-05-01), Fassler
patent: 4577949 (1986-03-01), Geyken
Haag Siegfried
Korn Joachim
Durr Dental GmbH & Co KG
Hix L. T,.
Philpitt Fred
Rutledge D.
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