Arrangement for detecting spatial inhomogeneities in a dielectric
First Claim
1. Arrangement for detecting spatial inhomogeneities in a dielectric for correlative measurement of the travel time or velocity of said inhomogeneities, the arrangement comprisinga transmitting electrode fed by an electrical supply voltage,at least one pair of sensor electrodes disposed opposite said transmitting electrode and spaced a distance therefrom so that said spatial inhomogeneities pass through the space between said transmitting electrode and said sensor electrodes, each pair of sensor electrodes including a first and second sensor electrode arrangement in side by side relation extending in the direction of travel of said spatial inhomogeneities and separated in said direction by a gap having a width which is small compared with the dimension of said transmitting electrode in said direction and compared with the effective spacing between said transmitter electrode and said at least one pair of sensor electrodes, andan electronic circuit associated with each pair of sensor electrodes, each electronic circuit including first means connected to its corresponding first sensor electrode for sensing the displacement current induced in said first electrode sensor and maintaining said corresponding first electrode sensor at any instant at a potential with respect to said supply voltage, second means connected to its corresponding second electrode sensor for sensing the displacement current induced in said corresponding second electrode sensor and maintaining said corresponding second electrode sensor at any instant at the same potential as said corresponding first electrode sensor with respect to said supply voltage, and third means for generating an output signal corresponding to the difference of the displacement currents sensed by said first and second means.
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Accused Products
Abstract
The arrangement includes a capacitive probe comprising pairs of sensor electrodes, arranged in a pseudo-random sequence, with which a common transmitting electrode is associated. The transmitting electrode is fed by an electrical voltage source and to the sensor electrodes of each pair an electrode circuit is connected which generates an output signal which corresponds to the difference of the displacement currents induced in the sensor electrodes. The electronic circuit is constructed such that it maintains the sensor electrodes at any time at a virtual ground potential. For this purpose each sensor electrode may be connected to the inverting input of an operational amplifier whose non-inverting input lies at the potential at which the sensor electrodes are to be held with respect to the supply voltage. The sensed signal is used in a correlative measurement of speed or travel time.
42 Citations
18 Claims
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1. Arrangement for detecting spatial inhomogeneities in a dielectric for correlative measurement of the travel time or velocity of said inhomogeneities, the arrangement comprising
a transmitting electrode fed by an electrical supply voltage, at least one pair of sensor electrodes disposed opposite said transmitting electrode and spaced a distance therefrom so that said spatial inhomogeneities pass through the space between said transmitting electrode and said sensor electrodes, each pair of sensor electrodes including a first and second sensor electrode arrangement in side by side relation extending in the direction of travel of said spatial inhomogeneities and separated in said direction by a gap having a width which is small compared with the dimension of said transmitting electrode in said direction and compared with the effective spacing between said transmitter electrode and said at least one pair of sensor electrodes, and an electronic circuit associated with each pair of sensor electrodes, each electronic circuit including first means connected to its corresponding first sensor electrode for sensing the displacement current induced in said first electrode sensor and maintaining said corresponding first electrode sensor at any instant at a potential with respect to said supply voltage, second means connected to its corresponding second electrode sensor for sensing the displacement current induced in said corresponding second electrode sensor and maintaining said corresponding second electrode sensor at any instant at the same potential as said corresponding first electrode sensor with respect to said supply voltage, and third means for generating an output signal corresponding to the difference of the displacement currents sensed by said first and second means.
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6. Arrangement for detecting spatial inhomogeneities in a dielectric for correlative measurement of the travel time or velocity of said inhomogeneities, comprising a transmitting electrode fed by an electrical supply voltage, first, second, and third sensor electrodes disposed opposite said transmitting electrode and spaced a distance therefrom so that said spatial inhomogeneities pass through the space between said transmitting electrode and said sensor electrode, said first and second sensor electrodes being arranged in side by side relation extending in the direction of travel of said spatial inhomogeneities to form a first pair of sensor electrodes and separated in said direction of travel by a first gap having a width which is small compared with the dimension of said transmitting electrode in said direction of travel and compared with the effective spacing between said transmitting electrode and said sensor electrodes, said second and third sensor electrodes being arranged in side by side relation extending in said direction of travel to form a second pair of sensor electrodes and separated in said direction of travel by a second gap having a width which is small compared with the dimension of said transmitting electrode in said direction of travel and compared with the effective spacing between said transmitting electrode and said sensor electrodes, and an electronic circuit including first means connected to said first sensor electrode for sensing the displacement current induced in said first sensor electrode and maintaining said first sensor electrode at any instant at a potential with respect to said supply voltage;
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second means connected to said second sensor electrode for sensing the displacement current induced in said second sensor electrode and maintaining said second sensor electrode at any instant at the same potential as said first sensor electrode with respect to said supply voltage; third means connected to said third sensor electrode for sensing the displacement current induced in said third sensor electrode and maintaining said third sensor electrode at any instant at the same potential as said first and second sensor electrodes with respect to said supply voltage, fourth means for generating an output signal corresponding to the differenceof the displacement currents sensed by said first and second means and fifth means for generating an output signal corresponding to the difference of the displacement currents sensed by said second and third means. - View Dependent Claims (7, 8, 9, 10)
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11. Arrangement for detecting spatial inhomogeneities in a dielectric for correlative measurement of the travel time or velocity of said inhomogeneities, comprising a transmitting electrode fe1 by an electrical supply voltage, at least one pair of sensor electrodes disposed opposite said transmitting electrode and spaced a distance therefrom so that said spatial inhomogeneities pass through the space between said transmitting electrode and said sensor electrodes, each sensor electrode being divided into a plurality of sub-electrodes, said sub-electrodes being arranged in side by side relation extending in the direction of travel of said spatial inhomogeneities and separated in said direction by gaps having widths which are small compared with the dimension of said transmitting electrode in said direction and compared with the effective spacing between said transmitter electrode and said at least one pair of sensor electrodes, and an electronic circuit including first means connected to the sub-electrodes of one of said sensor electrodes of said pair for generating an output signal corresponding to the sum of the displacement currents induced in said sub-electrodes and maintaining said sub-electrodes at any instant at a potential with respect to said supply voltage;
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second means connected to the sub-electrodes of the other sensor electrode of said pair for generating an output signal corresponding to the sum of the displacement currents induced in said sub-electrodes and maintaining said sub-electrodes at any instant at the same potential as the sub-electrodes of said first electrode with respect to said supply voltage and third means for generating an output signal corresponding to the difference of the output signals generated by said first and second means. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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Specification