Constant power dissipation in capacitance pressure transducers
AssigneeMKS Instruments, Inc.
InventorsPhilip J. Maiorana, Santhi E. Mathew
Life of this patent
Estimating the term…
Abstract
A system and method are described for maintaining power dissipation substantially constant across the sensor interface board of a capacitance pressure transducer. A shorted diaphragm level detector detects a shorting of the diaphragm onto one or more reference electrodes. A power dissipating resistor is placed near the oscillator that drives the capacitance detecting circuit in the capacitance pressure transducer. The resistor is switched across a power supply when the shorting is detected, causing current to flow through the resistor so that power can be added in an amount sufficient to maintain power dissipation by the oscillator substantially constant when the diaphragm shorts.
Claims20
A system for controlling power dissipation in a capacitance pressure transducer having a capacitance detecting circuit configured to detect a change in capacitance between a diaphragm and a reference electrode, the system comprising:
- a shorted diaphragm level detector configured to detect a shorting of the diaphragm onto the reference electrode;
- and
- a switch configured to cause a current to be transmitted through a resistor, when the shorting of the diaphragm has been detected, thereby maintaining power dissipation in the transducer substantially constant when the diaphragm shorts.
A system for controlling power dissipation in a capacitance pressure transducer that measures pressure by detecting a change in capacitance between a diaphragm and a reference electrode, the system comprising:
- a detecting circuit configured to detect a shorting of a diaphragm onto a reference electrode;
- and
- a power dissipation circuit configured to add power to the capacitance pressure transducer, when the shorting of the diaphragm onto the reference electrode has been detected, by sending a current through a resistor connected to an oscillator that drives a capacitance bridge circuit that detects the change in capacitance between the diaphragm and the reference electrode.
A capacitance pressure transducer, comprising:
- a diaphragm;
- one or more reference electrodes;
- a capacitance detecting circuit configured to detect a change in capacitance between a diaphragm and a reference electrode, the change in capacitance being proportional to pressure applied to the diaphragm;
- an oscillator configured to drive the capacitance detecting circuit;
- a shorted diaphragm level detector configured to detect a shorting of the diaphragm onto the reference electrode;
- a resistor coupled to the oscillator;
- and
- a switch configured to allow a current to be transmitted through the resistor, in response to detection of the shorting of the diaphragm, so as to maintain power dissipation by the transducer substantially constant when the diaphragm shorts.
A method of controlling power dissipation in a capacitance pressure transducer configured to measure pressure by detecting a change in capacitance between a diaphragm and a reference electrode, the method comprising:
- detecting a shorting of the diaphragm onto the reference electrode;
- and
- adding power dissipation in the transducer by an amount sufficient to compensate for reduction in power dissipation in the transducer caused by the shorting of the diaphragm, thereby maintaining power dissipation in the transducer substantially constant.
Dependencies are inferred from the claim text.