Chemistry: electrical and wave energy – Apparatus – Electrolytic
Reexamination Certificate
1999-03-08
2001-05-08
Warden, Sr., Robert J. (Department: 1744)
Chemistry: electrical and wave energy
Apparatus
Electrolytic
C204S406000, C204S435000, C324S714000, C396S578000
Reexamination Certificate
active
06228237
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to the automatic measurement of the concentration of a developing agent in a developing bath, and in particular to a device for automatically measuring the concentration of a developing agent.
BACKGROUND OF THE INVENTION
Developing baths for photographic films comprise developing agents that are reducing compounds. As it is used, the developing bath becomes depleted in developing agent due to the development itself(redox reaction), and also due to aerial oxidation. This decrease of developing agent concentration causes a reduction of bath activity. In order to maintain bath activity, the bath has to be regularly replenished so as not to alter the quality of the developed products. However, it is desirable to replenish it so as to compensate solely for the variation of developing agent concentration. For this reason, regular and fast measurement of developing agent concentration in developing baths is desired.
Procedures for measuring the concentration of developing agents are known that include using a voltammetric method. Three-electrode cells are used to take measurements; they comprise three electrodes not fixed one to another. The operator who carries out the measurement arranges the electrodes in relation to one another in a position that allows correct measurement. One problem that occurs with this use is that the variation of position of the electrodes in relation one to another causes variations of the measurements. Another problem that occurs with this type of cell is that the measurement cannot be taken directly in the solution containing the developing agents. The solution is sampled and added into the cell. But the reaction continues to take place in the time that the solution is sampled and added into the cell. Thus the measurement that is taken in the cell does not allow the developing agent concentration in the developing bath to be obtained accurately. Furthermore, aerial oxidation can take place during the sampling.
On the other hand, procedures for measuring developing agent concentration that include using a voltammetric method use expensive apparatuses, which also requires operators to know about the chemical reactions that are taking place in developing baths and a certain number of adjustments.
SUMMARY OF THE INVENTION
An object of the present invention is to develop a device for measuring the concentration of a developing agent that does not have the drawbacks described above, and in particular a mobile device that is easy to use and has a low cost.
The invention relates to a device for automatically measuring a concentration of a developing agent in a developing bath. The device comprises a voltage generator capable of generating at least one voltage ramp for feeding a three-electrode cell; a potentiostat provided to maintain constant potential difference between two electrodes; a peak detector provided to identify the maximum current flowing in the three-electrode cell that corresponds to the concentration of the developing agent; and a display unit provided to show the maximum current.
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K. Brunt; “New Electrochemical Detector for High-performance Liquid Chromatography”, Journal of Chromatography, vol. 161, 1978, pp. 310-314.
Goumont Claude G.
Roussilhe Jacques
Sirand-Rey Gerard R.
Eastman Kodak Company
Novais David A.
Olsen Kaj K.
Warden, Sr. Robert J.
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