Tomographic flow imaging system
First Claim
1. A tomographic flow imaging system, comprising three or more capacitance electrodes monitored passes, means for measuring the capacitance between each pair of the electrodes, and means for deriving from the measured capacitances an output representative of the distribution of material within the pipe, wherein means are provided for applying a predetermined voltage signal to one electrode at a time, and means are provided for connecting each electrode other than said one electrode to sources of equal fixed potential, the capacitance of each pair of electrodes being measured by measuring charge flowing between the said other electrode of the pair and the source of potential to which it is connected.
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Abstract
A tomographic flow imaging system comprising three or more capacitance electrodes positioned around a pipe through which a flow to be monitored passes. The capacitance between each pair of the electrodes is measured, and an output is derived from the measured capacitances which is representative of the distribution of material within the pipe. A predetermined voltage signal is applied to one electrode at a time, and the electrodes other than said one electrode are connected to sources of equal fixed potential. The capacitance of each pair of electrodes is measured by measuring charge flowing between the said other electrode of the pair and the source of potential to which it is connected.
41 Citations
10 Claims
- 1. A tomographic flow imaging system, comprising three or more capacitance electrodes monitored passes, means for measuring the capacitance between each pair of the electrodes, and means for deriving from the measured capacitances an output representative of the distribution of material within the pipe, wherein means are provided for applying a predetermined voltage signal to one electrode at a time, and means are provided for connecting each electrode other than said one electrode to sources of equal fixed potential, the capacitance of each pair of electrodes being measured by measuring charge flowing between the said other electrode of the pair and the source of potential to which it is connected.
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10. A circuit for measuring the capacitance of a capacitor formed by a pair of electrodes, comprising first and second pairs of switches arranged such that one switch of each pair is connected to a respective electrode, wherein a first switch of the first pair is connected between its respective electrode and a first source of fixed potential, a second switch of the first pair is connected between its respective electrode and a second source of fixed potential, a first switch of the second pair is connected between its respective electrode and the second source of fixed potential, and the second switch of the second pair is connected between its respective electrode and an input to a charge measuring circuit, the said input being maintained at the potential of the said second source of fixed potential, and means being provided to close the first pair of switches to charge the said capacitor, and to then open the first pair of switches and close the second pair of switches to discharge the capacitor into the charge measuring circuit.
Specification