Digital silver ion concentration controller for the precipitation of silver halide emulsions
First Claim
1. Apparatus for controlling the concentration of silver ions during the precipitation of a silver halide in a precipitation vessel comprising:
- a first means for controllably introducing a silver salt into said precipitation vessel;
a second means for controllably introducing a halide salt into said precipitation vessel;
an ion sensor positioned in said precipitation vessel for generating a voltage representative of the amount of silver ion in solution therein;
a temperature sensor positioned in said precipitation vessel for generating a voltage representative of the temperature of the silver ion solution therein;
means for converting the ion sensor voltage and the temperature sensor voltage to digital values;
computer means for receiving the digital values of the ion sensor and the temperature sensor for converting the digital value of the ion sensor to a digitized concentration value by computing the equation;
wherein;
R is a gas constantT is the absolute temperature of the solution in degrees KelvinF is the Faraday constant and by transforming the digitized concentration value to an equivalent constant coefficient differential equation;
space="preserve" listing-type="equation">dY/dt+aY=bD+bU where;
Y=[Ag+]1/n and where;
n=2D is the disturbance of the systemU is the control effortb is a constant, anda is a constant;
means for comparing the transformed digitized concentrated value against a digitized set point value to provide a difference signal; and
means for controlling said first and said second means as a function of said difference signal so as to drive said difference signal towards a zero value.
1 Assignment
0 Petitions
Accused Products
Abstract
Apparatus for controlling the concentration of silver ions during the precipitating of a silver halide emulsion in a precipitation vessel. The introduction of a silver salt and a halide salt is controlled in accordance with a preselected program, which in turn is responsive to the silver ion concentration measured in the vessel by a silver ion sensor. Linerization of the output signal from the sensor is accomplished by converting the sensor'"'"'s output voltage into a concentration voltage through the use of a Nernst equation and by transforming the concentration voltage into a variable value denoted Y representing a constant coefficient differential equation that is linear. The linear equation is then used to control the addition of the silver salt and the halide salt to the precipitation vessel.
-
Citations
4 Claims
-
1. Apparatus for controlling the concentration of silver ions during the precipitation of a silver halide in a precipitation vessel comprising:
-
a first means for controllably introducing a silver salt into said precipitation vessel; a second means for controllably introducing a halide salt into said precipitation vessel; an ion sensor positioned in said precipitation vessel for generating a voltage representative of the amount of silver ion in solution therein; a temperature sensor positioned in said precipitation vessel for generating a voltage representative of the temperature of the silver ion solution therein; means for converting the ion sensor voltage and the temperature sensor voltage to digital values; computer means for receiving the digital values of the ion sensor and the temperature sensor for converting the digital value of the ion sensor to a digitized concentration value by computing the equation; wherein; R is a gas constant T is the absolute temperature of the solution in degrees Kelvin F is the Faraday constant and by transforming the digitized concentration value to an equivalent constant coefficient differential equation;
space="preserve" listing-type="equation">dY/dt+aY=bD+bUwhere;
Y=[Ag+]1/nand where; n=2 D is the disturbance of the system U is the control effort b is a constant, and a is a constant; means for comparing the transformed digitized concentrated value against a digitized set point value to provide a difference signal; and means for controlling said first and said second means as a function of said difference signal so as to drive said difference signal towards a zero value.
-
-
2. Method for controlling the concentration of silver ions during the precipitation of a silver halide in a precipitation vessel comprising the steps of:
-
(a) measuring the amount of silver ion in the precipitation vessel with an ion sensor to provide a measured value; (b) converting the measured value to a concentration value; (c) transforming the concentration value to an equivalent constant coefficient differential equation; and (d) controlling the amount of silver ions added to the precipitation vessel as a function of the constant coefficient differential equation. - View Dependent Claims (3, 4)
-
Specification