Eastman-kodak Company

Nicholas J Dartnell

Christopher B Rider

Andrew Clarke

Bruce S Gowans

Christopher Barrie Rider

A method and device for periodically perturbing the flow field within a microfluidic device to provide regular droplet formation at high speed.

Droplet generator

A method and device for passively periodically perturbing the flow field within a microfluidic device to cause regular droplet formation at high speed.

A method of processing photographic material includes the steps of processing the photographic material in a processing solution, monitoring the concentration of a process-retarding by-product of the processing in the processing solution during operation of the method, reducing the concentration of the by-product in the processing solution by a first method and as the by-product concentration in the processing solution exceeds a predetermined level, activating simultaneous operation of a second method for a period of time to thereby ensure that the photographic material is always adequately processed. The invention enables rapid processing of film whilst maintaining low replenishment rates and low fixer solution temperature such that inadequately fixed film is avoided.

Method and system for processing of photographic materials

The invention provides a method for calculating the fractional exposure of black and white photographic material, the developed material being processed in a processing system having a fixing stage and an in-line silver recovery unit associated with the fixing stage, comprising the steps of determining the mass of silver recovered by the in-line silver recovery unit during a period of operation of the method, calculating a first estimate for the fractional exposure of the photographic material in dependence on the determined mass of silver and, using said first estimate as an input to an iterative process, to calculate a subsequent estimate for the fractional exposure (&thgr;) of the photographic material. The invention provides a simple and accurate method and system for calculating the fractional exposure of photographic material without requiring the use of a silver sensor.

Method and system for calculating the fractional exposure of photographic material

The invention relates to a method for controlling the recovery of a metal, such as silver, from a solution flowing through an electrolytic cell. A constant current is applied between the anode and cathode of the cell and the rate of change of the voltage monitored, the information obtained from the monitored change of voltage being used to control the rate of recovery of the metal.

Recovery of metal from solution

An electrolytic cell for the recovery of silver from a photographic fixer solution is of generally cylindrical configuration. The cell has a screw-on lid that carries the disposable cathode of the cell. Inlet and outlet for the solution are at the bottom of the cell. The anode is tubular and extends upwardly from the outlet at the base of the cell towards the lid. The cathode is easily replaced, together with the lid, and flow through and the dimensions of the cell are arranged to avoid entrapment of gas therein.

Electrolytic cell

Recovery of silver from a photographic fixer solution in an electrolytic cell is controlled so as to maintain a high current efficiency whilst minimizing unwanted side effects. The difference between plating voltages when operating at two different current levels is monitored, and the plating current adjusted in response to detection of a maximum of said differences. Such control allows the cell to be operated continually at high current efficiency in response to changing chemical conditions within the cell.

Recovery of silver from a photographic fixer solution in an electrolytic cell is controlled so as to maintain a high current efficiency whilst minimizing unwanted side effects. The rate of change of plating voltage at constant current through the cell is monitored, and in response to detection of a maximum value thereof the current is reduced to a new constant level. Such control allows the cell to be operated continually at high current efficiency in response to changing chemical conditions within the cell.

Growing community of inventors

Longstanton, United Kingdom

Nicholas J Dartnell