Digital transducer system including two reactive transducers forming resonant oscillator circuits
AssigneeTavis Corporation
InventorsJohn R. Tavis, Laurence R. Nicholson
Life of this patent
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Abstract
A variable reluctance transducer system incorporating digital control of parallel resonant circuits including two inductive sensors L1 and L2 on each side of a flat diaphram. The dual variable reluctance elements provide dual frequency signals for digital calculation to obtain a quotient of the frequencies, thereby substantially eliminating the resonant frequencies as a variable in the accuracy of the device. Manipulation of the produced quotient by a micro-controller 10 employing digital calibration tables stored in a programmable read only memory 14 allows calibration reponsive to a temperature sensor 16, thereby substantially eliminating temperature induced errors in the system, further increasing accuracy.
Claims6
A digital transducer system receiving a force input, the system comprising:
- a first resonant circuit activated by a first control signal and having a first variable resonant frequency dependant on the force input;
- a second resonant circuit activated by a second control signal;
- a means for producing the first control signal and the second control signal at predetermined times;
- a means for frequency measurement connected to the first resonant circuit and second resonant circuit;
- means for calculating a quotient of the first frequency and second frequency;
- means for calculating a transducer value proportional to the quotient;
- means for calibrating the transducer value to provide a system output;
- and
- oscillator control means receiving a frequency signal from the first and second resonant circuits, when activated, for providing feedback to the first and second resonant circuits to maintain constant amplitude oscillation.
An oscillator controller for use in a digital transducer system having parallel resonant circuits, the controller comprising:
- an amplifier receiving the frequency signal from the first and second resonant circuits;
- a detector receiving an output from the amplifier;
- a chopper receiving as a first input an output from the detector;
- a reference means for providing a voltage reference for the detector, the reference means having an output connected as a second input to the chopper;
- and
- feedback means receiving an output from the chopper and connected to the resonant circuits.
Dependencies are inferred from the claim text.