Fluid flow rate measuring device and water meter
원문보기
IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
G01F-001/56
G01D-004/02
G01F-001/075
G01F-001/58
G01F-015/075
G01F-001/60
출원번호
US-0754512
(2013-01-30)
등록번호
US-10156463
(2018-12-18)
우선권정보
JP-2012-018319 (2012-01-31)
발명자
/ 주소
Yonezawa, Yoshiaki
Kondo, Hideo
출원인 / 주소
Semiconductor Components Industries, LLC
대리인 / 주소
Dover, Rennie William
인용정보
피인용 횟수 :
0인용 특허 :
23
초록▼
A water meter that requires neither a smoothing capacitor of large capacitance nor a high frequency reference clock is offered. A rotation detection unit is formed to include a first coil, a first capacitor, a charging transistor, a power supply line, an activation transistor, an output buffer circu
A water meter that requires neither a smoothing capacitor of large capacitance nor a high frequency reference clock is offered. A rotation detection unit is formed to include a first coil, a first capacitor, a charging transistor, a power supply line, an activation transistor, an output buffer circuit, a DA converter, a comparator and a counter. A first LC resonant circuit is provided with the activation transistor connected in series with the first coil, the first capacitor connected in parallel with the first coil and the charging transistor for charging the first capacitor. The first LC resonant circuit is activated by turning on the activation transistor after the first capacitor is charged by turning on the charging transistor.
대표청구항▼
1. A fluid flow rate measuring device having a circular plate comprising a metal portion disposed on its principal surface and an insulator portion disposed on the rest of the principal surface and rotating at a rotation speed proportional to a flow rate of a fluid and measuring the flow rate of the
1. A fluid flow rate measuring device having a circular plate comprising a metal portion disposed on its principal surface and an insulator portion disposed on the rest of the principal surface and rotating at a rotation speed proportional to a flow rate of a fluid and measuring the flow rate of the fluid based on the rotation speed of the circular plate, comprising: an LC resonant circuit comprising a coil disposed above the principal surface of the circular plate, the coil having a first terminal and a second terminal, a first switching device connected in series with the coil, and a capacitor having a first terminal and a second terminal connected in parallel with the coil and the first switching device that are connected in series, wherein the first switching device has a control terminal and first and second current carrying terminals, the first current carrying terminal of the first switching device coupled for receiving a first source of operating potential, and the second current carrying terminal of the first switching device coupled to the first terminal of the coil, and wherein the first switching device is configured to have an adjustable ON resistance;a second switching device for charging the capacitor, the second switching device having a control terminal, a first current carrying terminal, and a second current carrying terminal, the second current carrying terminal of the second switching device coupled to the second terminal of the coil and the second terminal of the capacitor and the first current carrying terminal of the second switching device coupled for receiving a second source of operating potential, the second source of operating potential at a voltage greater than a voltage of the first source of operating potential;a resistor coupled between the second current carrying terminal of the second switching device and the coil, the LC resonant circuit being activated to output the oscillation signal by turning on the first switching device after the capacitor has been charged in response to turning on the second switching device;an output buffer circuit having an input, an output, a first supply terminal, and a second supply terminal, the output buffer circuit configured to change the ON resistance of the first switching circuit, to have an adjustable output impedance, and to output a switching signal for controlling turning on/off of the first switching device, wherein the output buffer circuit is configured so that a transition time of the switching signal at the turning on of the first switching device is adjustable;a charge pump coupled to the first supply terminal of the output buffer circuit and configured to change an output voltage level of the output buffer circuit, wherein the charge pump is configured to generate the output voltage level to be greater than the first source of operating potential and the second source of operating potential, and wherein the second supply terminal of the output buffer circuit is coupled for receiving an output impedance control signal to change the output impedance of the output buffer circuit;a comparator comparing the oscillation signal from the LC resonant circuit with a reference voltage;a counter having a first input, a second input, and an output, the first input of the counter coupled to the output of the comparator and the second input of the counter coupled for receiving a reset signal, the counter configured to count a number of pulses outputted from the comparator; andan arithmetic unit obtaining information on whether the coil is above the metal portion or above the insulator portion based on the number of pulses counted by the counter and calculating the rotation speed of the circular plate based on the information. 2. The fluid flow rate measuring device of claim 1, wherein the arithmetic unit resets the counter when the number counted by the counter is smaller than a predetermined number. 3. The fluid flow rate measuring device of claim 1, wherein the arithmetic unit generates a flag showing an abnormal oscillation of the LC resonant circuit when the number counted by the counter is smaller than a predetermined number. 4. The fluid flow rate measuring device of claim 1, wherein the reference voltage is set variably. 5. The liquid flow rate measuring device of claim 4, wherein the reference voltage is generated by a DA converter. 6. The fluid flow rate measuring device of claim 1, wherein the arithmetic unit comprises a microcomputer. 7. A fluid flow rate measuring device having a circular plate comprising a metal portion disposed on a first portion of a principal surface and an insulator portion disposed on a second portion of the principal surface and rotating at a rotation speed proportional to a flow rate of a fluid and measuring the flow rate of the fluid based on the rotation speed of the circular plate, comprising: a first switching device having a control terminal, a first current carrying terminal and a second current carrying terminal, wherein the first current carrying terminal of the first switching device is coupled for receiving a first source of operating potential that is at a first voltage level;a first resistor coupled to the second current carrying terminal of the first switching device;a first LC resonant circuit comprising a second switching device connected in series with a first coil and a first capacitor connected in parallel with the second switching device and the first coil that are connected in series, the first coil disposed above the principal surface of the circular plate, wherein the second switching device has a control terminal, a first current carrying terminal, and a second current carrying terminal, the first current carrying terminal of the second switching device is connected to a first terminal of the first coil and the second current carrying terminal of the second switching device is coupled for receiving a second source of operating potential that is at a second voltage level and to a first terminal of the first capacitor, the first voltage level greater than the second voltage level, and wherein the second switching device is configured to have an adjustable ON resistance;a first buffer circuit having an input, an output, a first supply terminal, and a second supply terminal, the output of the first buffer circuit coupled to the control terminal of the second switching device and configured to change the ON resistance of the second switching device;a first charge pump coupled to the first supply terminal of the first buffer circuit and configured to change an output voltage level of the first buffer circuit and wherein the second supply terminal of the first buffer circuit is coupled for receiving a first output impedance control signal to change the output impedance of the first buffer circuit;a third switching device having a control terminal, a first current carrying terminal and a second current carrying terminal, wherein the first current carrying terminal of the third switching device is directly coupled for receiving the first source of operating potential at the first voltage level;a second resistor coupled to the second current carrying terminal of the third switching device;a second LC resonant circuit comprising a fourth switching device connected in series with a second coil and a second capacitor connected in parallel with the fourth switching device and the second coil that are connected in series, the second coil disposed above the principal surface of the circular plate, wherein the fourth switching device has a control terminal, a first current carrying terminal, and a second current carrying terminal, the first current carrying terminal of the fourth switching device is connected to a first terminal of the second coil and the second current carrying terminal of the fourth switching device is coupled for receiving the second source of operating potential at the second voltage level and to a first terminal of the second capacitor, and wherein the fourth switching device is configured to have an adjustable ON resistance;a second buffer circuit having an input, an output, a first supply terminal, and a second supply terminal, the output of the second buffer circuit coupled to the control terminal of the fourth switching device and configured to change the ON resistance of the fourth switching device;a second charge pump coupled to the first supply terminal of the second buffer circuit and configured to change an output voltage level of the second buffer circuit and wherein the second supply terminal of the second buffer circuit is coupled for receiving a second output impedance control signal to change the output impedance of the second buffer circuit;a fifth switching device having a control terminal, a first current carrying terminal and a second current carrying terminal, wherein the first current carrying terminal of the fifth switching device is directly coupled for receiving the first operating potential at the first voltage level;a third resistor coupled to the second current carrying terminal of the fifth switching device;a third LC resonant circuit comprising a sixth switching device connected in series with a third coil and a third capacitor connected in parallel with the sixth switching device and the third coil that are connected in series, the third coil disposed above the principal surface of the circular plate, wherein the sixth switching device has a control terminal, a first current carrying terminal, and a second current carrying terminal, the first current carrying terminal of the sixth switching device connected to a first terminal of the third coil and the second current carrying terminal of the sixth switching device coupled for receiving the second source of operating potential at the second voltage level and to a first terminal of the third capacitor, and wherein the sixth switching device is configured to have an adjustable ON resistance;a third buffer circuit having an input, an output, a first supply terminal, and a second supply terminal, the output of the third buffer circuit coupled to the control terminal of the sixth switching device and configured to change the ON resistance of the sixth switching device;a third charge pump coupled to the first supply terminal of the third buffer circuit and configured to change an output voltage level of the third buffer circuit and wherein the second supply terminal of the third buffer circuit is coupled for receiving a third output impedance control signal to change the output impedance of the third buffer circuit; whereinthe second switching device is configured for charging the first capacitor, wherein the first LC resonant circuit is configured to be activated to output an oscillation signal by turning on the second switching device after the first capacitor has been charged in response to turning on the first switching device;a comparator comparing the oscillation signal from each of the LC resonant circuits with a reference voltage;a counter counting a number of pulses outputted from the comparator; andan arithmetic unit obtaining information on whether each of the coils is above the metal portion or above the insulator portion based on the number of pulses counted by the counter and calculating the rotation speed of the circular plate based on the information. 8. The fluid flow rate measuring device of claim 7, further comprising a selection circuit sequentially selecting each of a plurality of the oscillation signals outputted from the first, second, and third LC resonant circuits, wherein periods during each of which the oscillation signal from each of the first, second, and third LC resonant circuits is outputted are displaced from each other by displacing periods during each of which the first switching device in each of the first, second, and third LC resonant circuits is turned on from each other, and wherein the comparator compares the oscillation signal selected by the selection circuit with the reference voltage. 9. The fluid flow rate measuring device of claim 7, wherein the arithmetic unit resets the counter when the number counted by the counter is smaller than a predetermined number. 10. The fluid flow rate measuring device of claim 7, wherein the arithmetic unit generates a flag showing an abnormal oscillation of at least one of the first, second, and third LC resonant circuits when the number counted by the counter is smaller than a predetermined number. 11. A water meter comprising: a circular plate comprising a metal portion disposed on its principal surface and an insulator portion disposed on the rest of the principal surface, the circular plate rotating at a rotation speed proportional to a flow rate of water;a first switching device having a control terminal, a first current carrying terminal, and a second current carrying terminal;a first resistor coupled to the second current carrying terminal of the first switching device;an LC resonant circuit comprising a coil disposed above the principal surface of the circular plate, a second switching device connected in series with the coil and a capacitor connected in parallel with the coil and the second switching device that are connected in series, wherein the first switching device is configured for charging the capacitor, the LC resonant circuit being activated to output an oscillation signal by turning on the second switching device after the capacitor has been charged in response to turning on the first switching device, wherein the second switching device has a control terminal and first and second current carrying terminals, the first current carrying terminal of the second switching device coupled for receiving a first source of operating potential, and the second current carrying terminal of the second switching device coupled to the first terminal of the coil, and wherein the second switching device is configured to have an adjustable ON resistance;an output buffer circuit having an input, an output, a first supply terminal, and a second supply terminal, the output of the output buffer circuit coupled to the control terminal of the first switching device and configured to change the ON resistance of the first switching device;a charge pump coupled to the first supply terminal of the buffer circuit and configured to change an output voltage level of the output buffer circuit and wherein the second supply terminal of the output buffer circuit is coupled for receiving an output impedance control signal to change the output impedance of the output buffer circuit;a comparator comparing the oscillation signal from the LC resonant circuit with a reference voltage;a counter counting a number of pulses outputted from the comparator; andan arithmetic unit obtaining information on whether the coil is above the metal portion or above the insulator portion based on the number of pulses counted by the counter and calculating the rotation speed of the circular plate based on the information. 12. The water meter of claim 11, wherein the arithmetic unit resets the counter when the number counted by the counter is smaller than a predetermined number. 13. The water meter of claim 11, wherein the arithmetic unit generates a flag showing an abnormal oscillation of the LC resonant circuit when the number counted by the counter is smaller than a predetermined number. 14. The water meter of claim 11, wherein the output buffer circuit outputs a switching signal for controlling turning on/off of the second switching device, and wherein the output buffer circuit is configured so that a transition time of the switching signal at the turning on of the second switching device is adjustable. 15. The water meter of claim 11, wherein the reference voltage is set variably. 16. The water meter of claim 15, wherein the reference voltage is generated by a DA converter. 17. The water meter of claim 11, wherein the arithmetic unit comprises a microcomputer. 18. A fluid flow rate measuring device configured to measure a flow rate of the fluid in response to a rotation speed of a circular plate having an insulator portion and a metal portion where the plate rotates in response to the flow rate of the fluid, the flow rate measuring device comprising: an LC resonant circuit comprising a coil disposed above the circular plate, a first switching device connected in series with the coil, and a capacitor connected in parallel with the coil and the first switching device that are connected in series, the first switching device having a control terminal, a first current carrying terminal, and a second current carrying terminal, wherein the first switching device is configured to have an adjustable ON resistance;a second switching device for charging the first capacitor, the second switching device having a control terminal, a first current carrying terminal, and a second current carrying terminal;a first resistor coupled between the second current carrying terminal of the second switching device and the coil and between the second current carrying terminal of the second switching device and the capacitor, the LC resonant circuit being activated to output an oscillation signal by turning on the first switching device after the capacitor has been charged in response to turning on the second switching device;a buffer circuit having an input, an output, a first supply terminal, and a second supply terminal, the output of the buffer circuit coupled to the control terminal of the first switching device and configured to change the ON resistance of the first switching device;a charge pump coupled to the first supply terminal of the buffer circuit and configured to change an output voltage level of the buffer circuit and wherein the second supply terminal of the buffer circuit is coupled for receiving an output impedance control signal to change the output impedance of the buffer circuit;a comparator having a first input, a second input, and an output, the comparator configured to compare the oscillation signal from the LC resonant circuit at the first input with a reference voltage at the second input;a counter having a first input, a second input, and an output and configured for counting a number of pulses outputted from the comparator, the first input of the counter coupled to the output of the comparator, and the second input of the counter coupled for receiving a reset signal; andan arithmetic logic unit coupled to the output of the counter. 19. The fluid flow rate measuring device of claim 18, further comprising a digital to analog converter circuit coupled to the second input of the comparator to provide the reference voltage. 20. The fluid flow measuring device of claim 18, wherein the charge pump changes the output voltage level of the buffer circuit to a level that is greater than a voltage at the second current carrying terminal of the first switching device and greater than a voltage at the first current carrying terminal of the second switching device. 21. The fluid flow rate measuring device of claim 7, wherein the charge pump sets the output voltage level of the first buffer circuit is greater than the first voltage level and the second voltage level. 22. The water meter of claim 11, wherein the charge pump changes the output voltage level of the output buffer circuit to a level greater than a voltage level of the first source of operating potential.
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