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US 4,392,383 AGranted
Distance-frequency transducer
AssigneeRobert Bosch GmbH
InventorsHans Bauerlen, Thomas Pfendler, Berthold Wocher
Life of this patent
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Abstract
The distance-frequency transducer includes a capacitor whose capacitance changes as a function of movement of one electrode relative to the other. The movement is controlled by the parameter to be measured, as, for example, the pressure in a pressure pickup. The capacitance determines the frequency of an RC oscillator. The output frequency of the oscillator can be calibrated directly in pressure units.
Claims10
Pressure transducer comprising an RC oscillator circuit including
- a measuring capacitor having a capacitance (C) varying in dependence on pressure, and determining the frequency of the RC oscillator circuit, said capacitor having
- a fixed electrode (E1) and a movable electrode (E2);
- wherein the fixed electrode comprises a layer of electrically conductive material surrounding a central area which comprises non-conductive material (100),
- and wherein the movable electrode comprises a metallic, corrugated membrane (M) having a surface facing said fixed electrode, said membrane (M) forming a pressure pick-up (D) and being movable relative to said fixed electrode (E1) as a function of pressure applied thereon.
1 more element
Distance-frequency transducer comprising
- an RC oscillator circuit including
- an operational amplifier having a direct input forming an integrator circuit;
- a Schmitt trigger circuit connected to the integrator circuit;
- and
- a measuring capacitor having a capacitance (C) varying in dependence on distance, connected to said operational amplifier, for controlling the frequency thereof in dependence on the capacitance of the capacitor;
- said capacitor having a fixed electrode (E1) and a ring electrode (E5) surrounding said fixed electrode, said ring electrode being connected to the direct input of the operational amplifier.
3 more elements
Dependencies are inferred from the claim text.