IPC분류정보
국가/구분 |
United States(US) Patent
등록
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국제특허분류(IPC7판) |
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출원번호 |
US-0568551
(1984-01-05)
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발명자
/ 주소 |
- Czarnocki, Wlodzimierz S.
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출원인 / 주소 |
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대리인 / 주소 |
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인용정보 |
피인용 횟수 :
15 인용 특허 :
8 |
초록
▼
An electronic pressure transducer for providing a pressure-indicative analog output signal includes a capacitive pressure sensing oscillator having a frequency dependent on an applied pressure. A combining circuit combines the oscillator signal with a constant frequency signal generated by a referen
An electronic pressure transducer for providing a pressure-indicative analog output signal includes a capacitive pressure sensing oscillator having a frequency dependent on an applied pressure. A combining circuit combines the oscillator signal with a constant frequency signal generated by a reference oscillator to generate a difference signal having a duty cycle dependent on the frequency difference between the oscillator signals. The difference signal is applied to an integrating circuit and amplified by a variable-gain output amplifier to develop the pressure-indicative analog output signal. A pair of D-type flip-flops and an EXCLUSIVE OR logic gate in the combining circuit enable the combining circuit to function with oscillator frequency ratios of 1:1 to 2:1, thereby enabling the capacitive pressure sensing element of the pressure sensing oscillator to operate over a wider range of sensitivities. Non-linearities at the output of the integrating circuit are compensated for by a linearizing transistor having main electrodes coupled to a degenerative feedback network in the output amplifier. A second transistor having main electrodes coupled to the control electrode of the linearizing transistor compensates for temperature variations in the conduction level of the linearizing transistor.
대표청구항
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1. An electronic pressure transducer for providing a pressure-indicative output signal indicative of an applied pressure, comprising: a reference oscillator providing a reference signal having a frequency independent of the applied pressure; a sensor oscillator providing a pressure signal having
1. An electronic pressure transducer for providing a pressure-indicative output signal indicative of an applied pressure, comprising: a reference oscillator providing a reference signal having a frequency independent of the applied pressure; a sensor oscillator providing a pressure signal having a frequency dependent on the applied pressure; combining means for providing a difference signal having a duty cycle related to the frequency difference between said reference signal and said pressure signal over a relative frequency range of 2:1 to 1:1; and integrating circuit means responsive to said duty cycle for providing the pressure-indicative output signal. 2. An electronic pressure transducer as defined in claim 1 wherein said sensor oscillator includes a capacitive pressure sensor responsive to the applied pressure. 3. An electronic pressure transducer as defined in claim 1 wherein of said reference oscillator and said sensor oscillator have substantially identical temperature coefficients. 4. An electronic pressure transducer as defined in claim 1 wherein said combining means comprise said first and second flip-flop logic elements and a combining logic element, said first flip-flop being conditioned to one state by said reference signal, and to its other state by said sensor oscillator, said second flip-flop being conditioned to one state by said reference oscillator in alteration with said first flip-flop, and to its other state by said first flip-flop, and said combining logic element being responsive to said first and second flip-flops for producing said variable duty cycle difference signal. 5. An electronic pressure transducer as defined in claim 4 wherein said flip-flops are D-type flip flops each having clock and data inputs and Q and Q outputs, the clock input of said first flip-flop being connected to said reference oscillator, the data input of said first flip-flop being connected to said sensor oscillator, the clock input of said second flip-flop being connected through an inverter to said reference oscillator, the data input of said second flip-flop being connected to the Q output of said first flip-flop, and said combining logic element has one input connected to one output of said first flip-flop, and one input connected to one output of said second flip-flop. 6. An electronic pressure transducer as defined in claim 5 wherein said combining logic element comprises an EXCLUSIVE OR gate. 7. An electronic pressure transducer as defined in claim 6 wherein the inputs of said EXCLUSIVE OR gate are connected to respective Q outputs of said first and second flip-flops. 8. An electronic pressure transducer for providing a pressure-indicative output signal indicative of an applied pressure, comprising: a reference oscillator providing a reference signal having a frequency independent of the applied pressure; a sensor oscillator providing a pressure signal having a frequency dependent on the applied pressure; combining means comprising first and second flip-flop logic elements and a combining logic element having first and second inputs, said first flip-flop being conditioned to one state by said reference oscillator signal, and to its other state by said oscillator signal, said second flip-flop being conditioned to one state by said reference oscillator signal in alteration with said flip-flop, and to its other state by said first flip-flop, said first input of said combining logic element being connected to the output of said first flip-flop, said second input of said combining logic element being connected to the output of said second flip-flop, for providing at the output of said combining means a difference signal having a duty cycle dependent on the frequency difference between said sensor and said reference signals; and integrating circuit means responsive to said duty cycle for providing the pressure-indicative output signal. 9. An electronic pressure transducer as defined in claim 8 wherein said flip-flops are D-type flip-flops each having clock and data inputs and Q and Q outputs, the clock input of said first flip-flop being connected to said reference oscillator, the data input of said first flip-flop being connected to said sensor oscillator, the clock input of said second flip-flop being connected through an inverter to said reference oscillator, the data input of said second flip-flop being connected to the Q output of said first flip-flop, and said combining logic element has one input connected to one output of said first flip-flop, and one input connected to one output of said second flip-flop. 10. An electronic pressure transducer as defined in claim 9 wherein said combining logic element comprises an EXCLUSIVE OR gate. 11. An electronic pressure transducer as defined in claim 8 wherein said sensor oscillator includes a capacitive pressure sensor responsive to the applied pressure. 12. An electronic pressure transducer as defined in claim 8 wherein said reference oscillator and said sensor oscillator have substantially identical temperature coefficients. 13. An electronic pressure transducer for providing a pressure-indicative output signal indicative of an applied pressure, comprising: a reference oscillator providing a reference signal having a frequency independent of the applied pressure; a sensor oscillator providing a pressure signal having a frequency dependent on the applied pressure; combining means comprising first and second D-type flip-flop logic elements each having clock and data inputs and Q and Q outputs, an inverter, and a combining logic OR element having first and second inputs, the output of one of said oscillators being applied to the clock input of said first flip-flop, the output of the other of said oscillators being applied to the data input of said first flip-flop, the output of said one of said oscillators being applied through said inverter to the clock input of said second flip-flop, the Q output of said first flip-flop being applied to the data input of said second flip-flop, and said inputs of said logic OR element being connected to respective elements of said flip-flops, for providng at the output of said combining means a difference signal having a duty cycle dependent on the frequency difference between said sensor and reference signals; and integrating circuit means responsive to said duty cycle for providing the pressure-indicative output cycle signal. 14. An electronic pressure transducer as defined in claim 13 wherein said one oscillator comprises said reference oscillator, and said other oscillator comprises said pressure sensor oscillator. 15. An electronic pressure transducer as defined in claim 13 wherein said combining logic element comprises an EXCLUSIVE OR gate. 16. An electronic pressure transducer as defined in claim 15 wherein the inputs of said EXCLUSIVE OR gate are connected to respective Q outputs of said first and second flip-flops. 17. An electronic pressure transducer as defined in claim 13 wherein said sensor oscillator includes a capacitive pressure sensor responsive to the applied pressure. 18. An electronic pressure transducer as defined in claim 13 wherein the output frequencies of said reference oscillator and said sensor oscillator have substantially identical temperature response characteristics. 19. A linearized electronic pressure transducer for providing a pressure-indicative output signal indicative of an applied pressure, comprising: pressure sensing circuit means for providing an analog pressure signal having a magnitude varying as a predetermined function of sensed pressure, said pressure signal having an undesirable non-linear variation relative to sensed pressure; output circuit means coupled to said pressure sensing means and responsive to said analog signal for producing an analog output signal, said output circuit means having a transfer characteristic dependent on an applied control signal; and compensating circuit means responsive to said output signal for varying the transfer characteristic of said circuit means to compensate for said non-linear characteristic in said pressure signal whereby said output signal is linearly indicative of the applied pressure, wherein said output circuit comprises an amplifier having a degenerative feedback circuit, and said compensating circuit means are coupled to said feedback circuit, and wherein said compensating means comprise a transistor having principal electrodes connected between said feedback circuit and a plane of reference potential, and wherein a control electrode of said transistor is connected to a control potential. 20. A linearized electronic pressure transducer as defined in claim 19 wherein said transducer is operable over a predetermined temperature range, said transistor is subject to variations in conduction level with changes in temperature, and said linearity compensating circuit means include temperature compensating means coupled to the control electrode of said transistor for applying a control signal to said transistor to maintain the conduction level of said transistor constant with variations in temperature. 21. A linearized electronic pressure transducer as defined in claim 20 wherein said temperature compensating means comprise a temperature compensating transistor having principal electrodes coupled between said control electrode of said linearity compensating transistor and said plane of reference potential. 22. A linearized electronic pressure transducer as defined in claim 21 wherein said linearity compensating transistor is of one gender, and said temperature compensating transistor is of the opposite gender. 23. A linearized electronic pressure transducer as defined in claim 22 wherein said linearity transducer is an NPN transistor, and said temperature compensating transistor is a PNP transistor. 24. A linearized electronic pressure transducer for providing a pressure-indicative output signal indicative of an applied pressure, comprising: pressure sensing circuit means for providing an analog pressure signal having a magnitude varying as a predetermined function of sensed pressure, said pressure signal having an undesirable non-linear variation relative to sensed pressure; output circuit means coupled to said pressure sensing means and responsive to said analog signal for producing an analog output signal, said output circuit means having a transfer characteristic dependent on an applied control signal; and compensating circuit means responsive to said output signal for varying the transfer characteristic of said circuit means to compensate for said non-linear characteristic in said pressure signal whereby said output signal is linearly indicative of the applied pressure, wherein said output circuit comprises an amplifier and said compensating circuit means are coupled to said amplifier and wherein said compensating means comprise a transistor having principal electrodes, at least one of which being connected to said amplifier output signal, and wherein a control electrode of said transistor is connected to a control potential. 25. A linearized electronic pressure transducer as defined in claim 24 wherein said transducer is operable over a predetermined temperature range, said transistor is subject to variations in conduction level with changes in temperature, and said linearity compensating circuit means include temperature compensating means coupled to the control electrode of said transistor for applying a control signal to said transistor to maintain the conduction level of said transistor constant with variations in temperature. 26. A linearized electronic pressure transducer as defined in claim 25 wherein said temperature compensating means comprise a temperature compensating transistor having principal electrodes coupled between said control electrode of said linearity compensating transistor and one of said principal electrodes of said linearity compensating transistor. 27. A linearized electronic pressure transducer as defined in claim 24 wherein said transistor principal electrodes are connected between said amplifier output signal and a plane of reference potential.
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