Conductive liquid property measurement using multiple charge transfer times
First Claim
1. A liquid property measurement system comprising:
- a measurement cell having at least two conducting electrodes configured to receive a liquid between the at least two conducting electrodes;
a capacitor;
a voltage measurement circuit configured to determine a voltage on the capacitor;
a first switch coupled to the capacitor and in a current path between the capacitor and a voltage source; and
a second switch coupled to the capacitor and in a current path between the capacitor and the measurement cell,whereinthe first switch is initially open,the first switch is then closed to initially charge the capacitor and then opened, and a voltage on the capacitor is determined for an initial voltage measurement,after the first switch is opened, the second switch is closed for a first time period and then the voltage on the capacitor is determined for a first voltage measurement,the first switch is then closed to charge the capacitor again and then opened,after the first switch is opened, the second switch is closed for a second time period and then the voltage on the capacitor is determined for a second voltage measurement, andusing the initial voltage measurement, the first voltage measurement, and the second voltage measurement, a value is calculated related to the capacitance between the at least two conducting electrodes of the measurement cell.
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Accused Products
Abstract
Systems and methods for making repeatable measurements of the dielectric constant and conductivity of a material, such as a liquid. In one example, a material property measurement system includes a measurement cell, a voltage measurement circuit, a capacitor, and a switch. The measurement cell is made of at least two conducting electrodes with liquid between the conducting electrodes. The switch is in a current path between the capacitor and the measurement cell. The capacitor is charged and then the switch is closed for a first time period and a first voltage measurement on the capacitor is performed. The capacitor is charged again and the switch is closed for a second time period and a second voltage measurement on the capacitor is performed. The two voltage measurements are used in a calculation to calculate a value related to capacitance between the at least two conducting electrodes of the measurement cell.
18 Citations
18 Claims
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1. A liquid property measurement system comprising:
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a measurement cell having at least two conducting electrodes configured to receive a liquid between the at least two conducting electrodes; a capacitor; a voltage measurement circuit configured to determine a voltage on the capacitor; a first switch coupled to the capacitor and in a current path between the capacitor and a voltage source; and a second switch coupled to the capacitor and in a current path between the capacitor and the measurement cell, wherein the first switch is initially open, the first switch is then closed to initially charge the capacitor and then opened, and a voltage on the capacitor is determined for an initial voltage measurement, after the first switch is opened, the second switch is closed for a first time period and then the voltage on the capacitor is determined for a first voltage measurement, the first switch is then closed to charge the capacitor again and then opened, after the first switch is opened, the second switch is closed for a second time period and then the voltage on the capacitor is determined for a second voltage measurement, and using the initial voltage measurement, the first voltage measurement, and the second voltage measurement, a value is calculated related to the capacitance between the at least two conducting electrodes of the measurement cell. - View Dependent Claims (2, 3, 4)
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5. A method of measuring a property of a liquid using a liquid property measurement system, the method comprising:
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receiving the liquid between at least two conducting electrodes; initially charging a capacitor; determining an initial voltage on the capacitor; closing a switch connected to the capacitor to at least partially discharge the capacitor, wherein the switch is located on a current path between the capacitor and the at least two conducting electrodes; determining voltage on the capacitor after closing the switch to discharge the capacitor for a first time period to determine a first voltage; charging the capacitor again; determining voltage on the capacitor after closing the switch to discharge the capacitor for a second time period to determine a second voltage, wherein the first time period is a different length of time than the second time period; and calculating a value related to an impedance between the at least two conducting electrodes using the initial voltage, the first voltage and the second voltage. - View Dependent Claims (6, 7, 8)
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9. A capacitance measurement system comprising:
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a measurement cell having at least two conducting elements; a capacitor; a voltage measurement circuit configured to measure a voltage on the capacitor; a switch coupled to the capacitor and in a current path between the capacitor and the measurement cell, wherein the switch is initially open, the capacitor is initially charged and the voltage on the capacitor is measured for an initial voltage measurement, the switch is closed, after a first time period the voltage on the capacitor is measured for a first voltage measurement, and after a second time period the voltage on the capacitor is measured for a second voltage measurement, and using the initial voltage measurement, the first voltage measurement, and the second voltage measurement, a value is calculated related to the capacitance between the at least two conducting elements of the measurement cell. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A capacitance measurement system comprising:
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a measurement cell having at least two conducting elements; a capacitor; a voltage measurement circuit configured to measure a voltage on the capacitor; a switch coupled to the capacitor and in a current path between the capacitor and the measurement cell; a microprocessor configured to execute instructions that use a plurality of voltage measurements on the capacitor to calculate a value related to the charge sent through the switch to the measurement cell, wherein the charge sent through the switch to charge the measurement cell is used to calculate a value related to the capacitance between the two conducting elements of the measurement cell. - View Dependent Claims (16, 17, 18)
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Specification