Sintered pressure sensor for a pressure transmitter
First Claim
1. A pressure transmitter in a process control system for transmitting pressure on a process control loop, the transmitter comprising:
- a transmitter housing;
a pressure sensor body of a brittle corrosion resistant material operably coupled to the housing and positioned in the housing, the pressure sensor body comprising a first portion bonded to a second portion by a fusion bond, the fusion bond substantially free of foreign material, the pressure sensor body including a cavity formed between the first and second portions, the cavity having at least one dimension which changes in response to applied pressure;
first and second capacitive plates coupled to an interior wall of the cavity having a capacitance formed therebetween, the plates configured whereby a spacing between the plates changes as a function of the at least one dimension which changes in response to applied pressure;
first and second electrical conductors extending from an exterior of the pressure sensor body and electrically coupled to respective first and second capacitive plates;
a signal generator in the transmitter housing having a periodic output electrically coupled to the capacitance through at least one electrical conductor; and
an analog to digital converter in the transmitter housing having a digitized output as a function of the capacitance;
a loop interface in the transmitter housing configured to transmit a pressure related signal on the process control loop as a function of the digitized output, the interface further configured to completely power the transmitter with power received from the process control loop.
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Accused Products
Abstract
A transmitter in a process control system transmits a pressure over a process control loop. The transmitter includes I/O circuitry, compensation circuitry and an absolute pressure sensor. The I/O circuitry transmits information over the process control loop. Compensation circuitry receives a pressure related signal and responsively control'"'"'s the I/O circuitry to transmit pressure information on the loop. The absolute pressure sensor includes a cavity which deforms as the sensor deflects in response to an applied pressure. A sensor in the cavity provides the pressure related signal to the compensation circuitry in response to the deformation.
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Citations
42 Claims
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1. A pressure transmitter in a process control system for transmitting pressure on a process control loop, the transmitter comprising:
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a transmitter housing; a pressure sensor body of a brittle corrosion resistant material operably coupled to the housing and positioned in the housing, the pressure sensor body comprising a first portion bonded to a second portion by a fusion bond, the fusion bond substantially free of foreign material, the pressure sensor body including a cavity formed between the first and second portions, the cavity having at least one dimension which changes in response to applied pressure; first and second capacitive plates coupled to an interior wall of the cavity having a capacitance formed therebetween, the plates configured whereby a spacing between the plates changes as a function of the at least one dimension which changes in response to applied pressure; first and second electrical conductors extending from an exterior of the pressure sensor body and electrically coupled to respective first and second capacitive plates; a signal generator in the transmitter housing having a periodic output electrically coupled to the capacitance through at least one electrical conductor; and an analog to digital converter in the transmitter housing having a digitized output as a function of the capacitance; a loop interface in the transmitter housing configured to transmit a pressure related signal on the process control loop as a function of the digitized output, the interface further configured to completely power the transmitter with power received from the process control loop. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
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Specification