METHOD FOR SELF-MONITORING A CERAMIC PRESSURE MEASURING CELL OF A CAPACITIVE PRESSURE SENSOR AND EVALUATION CIRCUIT FOR CARRYING OUT SAID METHOD
First Claim
1. A method comprising:
- monitoring an operation of a pressure measuring cell of a capacitive pressure sensor, wherein a pressure measuring cell has a measuring capacitor and a reference capacitor and the pressure measuring value is obtained from the capacity values of the measuring capacitor (CM) and the reference capacitor;
wherein a control pressure measuring value is obtained with an auxiliary capacitor arranged outside the pressure measuring cell and the operability of the pressure measuring cell is inferred by comparing the pressure measuring value to the control pressure measuring value.
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Abstract
A method for monitoring the operation of a pressure measuring cell (10) of a capacitive pressure sensor (1), wherein the pressure measuring cell (10) has a measuring capacitor (CM) and a reference capacitor (CR) and the pressure measuring value (p) is obtained from the capacity values of the measuring capacitor (CM) and the reference capacitor (CR), characterized in that a control pressure measuring value (p′) is obtained with an auxiliary capacitor (CZ) arranged outside the pressure measuring cell (10) and the operability of the pressure measuring cell (10) is inferred by comparing the pressure measuring value (p) to the control pressure measuring value (p′) is provided.
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Citations
11 Claims
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1. A method comprising:
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monitoring an operation of a pressure measuring cell of a capacitive pressure sensor, wherein a pressure measuring cell has a measuring capacitor and a reference capacitor and the pressure measuring value is obtained from the capacity values of the measuring capacitor (CM) and the reference capacitor; wherein a control pressure measuring value is obtained with an auxiliary capacitor arranged outside the pressure measuring cell and the operability of the pressure measuring cell is inferred by comparing the pressure measuring value to the control pressure measuring value. - View Dependent Claims (5, 6, 7, 8)
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2. A method comprising:
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monitoring an operation of a pressure measuring cell of a capacitive pressure sensor, wherein the pressure measuring cell has a measuring capacitor and a reference capacitor and a pressure measuring value is obtained from the capacity values of the measuring capacitor and the reference capacitor; wherein a processing unit comprising at least one converter unit and a microcontroller is provided, in which the capacity values of the measuring capacitor as well as the reference capacitor are registered, the pressure measuring value is formed from the two capacity values, and another capacity value is registered, which corresponds to an auxiliary capacitor and from which a control pressure measuring value is obtained, wherein the operability of the pressure measuring cell is inferred by comparing the pressure measuring value to the control pressure measuring value. - View Dependent Claims (3, 4)
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9. An evaluation circuit for a capacitive sensor comprising:
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a measuring capacitor and a reference capacitor, wherein the reference capacitor is provided in a differential branch and the measuring capacitor is provided in an integrating branch, which are connected in parallel and on which a voltage signal is applied, wherein the output signal of the integrating branch is fed to the differential branch, at whose output a first pressure-dependent output signal is applied; wherein a control measuring branch is connected to an auxiliary capacitor in parallel with the differential branch and the output signal of the integrating branch is additionally fed to the control measuring branch, at whose output a second pressure-dependent output signal is applied, and both output signals, are fed to a comparator unit, at whose output a diagnosis signal is emitted. - View Dependent Claims (10, 11)
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Specification