JP2000081350A - High frequency electromagnetic induction switch and water quantity inspection unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high frequency electromagnetic induction switch for use in radio water quantity inspection unit which can operate for a long term without requiring maintenance/management, e.g. replacement of battery. SOLUTION: A capacitor C1 having capacity resonant in high frequency induction field is connected across a coil L1 formed by winding a thin insulated wire tubularly. A diode D for converting high frequency voltage into DC current is connected between one terminal of the coil L1 and the gate terminal of a field effect transistor Q1 and a voltage equal to gate cut-off voltage is applied to the field effect transistor Q1 through one terminal of the coil L1. A DC voltage is applied through a resistor to the drain terminal of the field effect transistor having source terminal connected with an earth terminal. A receiving section controls the electric switch of a CMOS integrated circuit IC2 based on the fluctuation of DC current at the drain terminal of the field effect transistor incident to fluctuation of high frequency induction field.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a high-frequency electromagnetic induction switch and a water meter reading device. More specifically, the present invention relates to a high-frequency electromagnetic induction switch capable of driving an electric switch from a remote location without requiring an electrical or mechanical connection, and a water flow using the high-frequency electromagnetic induction switch. The present invention relates to a meter reading device.

[0002]

Conventionally, as a meter reading operation for the usage of water, gas, kerosene, etc., a wire type automatic meter reading system utilizing the idle time of a telephone line has been partially adopted. The majority of the systems are for workers to visually read usage and input data directly to the handy terminal.

[0003] Of the conventionally adopted methods, the visual meter reading method has the problems that it takes time and effort to read the meter, which leads to an increase in cost, and that a meter reading error tends to occur. This is particularly remarkable in water meter reading work.When reading water meter usage, the meter reader opens the top cover of the handhole buried in the ground, and the water meter is installed in the handhole. Had to read the numbers.

[0004] The wire-based automatic meter reading system, which is partially adopted, has the advantage that the meter reading operation can be carried out efficiently and reliably. Since electrical wiring is required up to a water amount display unit attached to a building or the like, equipment costs are increased, and the wiring may be erroneously cut due to excavation work or the like.

On the other hand, in order to overcome the drawbacks of the visual meter reading system and the wire type automatic meter reading system, various researches and developments have been made on a wireless water meter reading system.
The wireless water meter reading system has the advantage that the meter reading is not troublesome, the meter reading is not mistaken, and there is no possibility that the wiring is cut off by mistake.However, the water meter is buried underground. Since it is installed in the hall, a battery must be used as a power source for the water quantity integrated data transceiver. Therefore, if the meter reading operation is to be carried out at any time without setting a specific meter reading date and time, the water volume integrated data transceiver must be constantly operated, which increases the load on the battery and causes the battery to be periodically charged. The problem is that a natural exchange becomes indispensable. In addition, since the water meter is buried underground, it is difficult to use a solar cell as a power source.

[0006] Under such circumstances, there is a strong demand for a wireless water meter reading system that can be operated for a long time without requiring maintenance such as battery replacement.

Accordingly, an object of the present invention is to provide a high-frequency electromagnetic induction switch for use in a wireless water meter reading system that can be operated for a long time without requiring maintenance such as battery replacement. .

[0008]

According to a first aspect of the present invention, there is provided a high-frequency electromagnetic induction switch including a capacitor having a capacitance that resonates with a high-frequency induction magnetic field at both ends of a coil in which an elongated insulating-coated conductor is wound in a cylindrical shape. Connected, a diode for converting a high-frequency voltage to a DC voltage is connected between one terminal of the coil and the gate terminal of the field effect transistor, and the field cutoff voltage is applied to the field effect transistor through the one terminal of the coil. Apply an equal voltage, apply a DC voltage to the drain terminal of the field-effect transistor through a resistor, connect the source terminal of the field-effect transistor to the ground terminal, and change the DC voltage of the drain terminal of the field-effect transistor due to a change in the high-frequency induction magnetic field. Changes in CMO
The present invention is characterized in that a receiver for controlling an electrical switch of the S integrated circuit is provided.

The high-frequency electromagnetic induction switch according to claim 2 of the present application is the high-frequency electromagnetic induction switch according to claim 1,
An electric switch of the CMOS integrated circuit, an inverter circuit connected to the field effect transistor, a set / reset latch circuit connected to the set terminal, and an inverted output of the set / reset latch circuit; Has a second field-effect transistor connected to the gate terminal, and the voltage output to the drain terminal of the second field-effect transistor becomes a signal for driving the power switch circuit. Is what you do.

According to a third aspect of the present invention, there is provided a water meter reading device, wherein the receiving portion of the high frequency electromagnetic induction switch according to the first or second aspect is attached to a water meter,
A high-frequency induction magnetic field induces a high-frequency voltage in the coil of the receiving unit, and the voltage is output, thereby supplying power to the water volume integration data transceiver attached to the water volume integration meter. Is what you do.

[0011]

Next, preferred embodiments of the present invention will be described in detail with reference to the drawings. First, the receiver of the high-frequency electromagnetic induction switch will be described,
The transmission section of the high-frequency electromagnetic induction switch will be described. FIG.
FIG. 2 is a circuit diagram showing a receiving unit of the high-frequency electromagnetic induction switch according to the preferred embodiment of the present invention. In FIG.
L1 indicates an electromagnetic induction receiving coil in which a long and thin insulated conductor is wound in a cylindrical shape, and a capacitor C1 is connected to both ends of the coil L1. The capacitor C1 has a capacity that resonates with a high-frequency electromagnetic induction magnetic field. Therefore, for example, when the electromagnetic induction frequency is 300 kHz, the inductance of the coil L1 is 2.8 mH,
The capacitance of 1 becomes 100 pF. The coil L1 and the capacitor C1 constitute a high-frequency electromagnetic induction resonance circuit that resonates with the high-frequency electromagnetic induction signal.

A diode D is connected between one terminal of the coil L1 and the gate terminal of the field effect transistor (FET) Q1. The diode D has a function of converting a high-frequency voltage induced in the high-frequency electromagnetic induction resonance circuit into a DC voltage. Preferably, the diode D has a small junction capacitance and good high-frequency characteristics in order to detect a small voltage induced by electromagnetic induction. In the present embodiment, a small signal Schottky barrier type diode is used as the diode D.

The field effect transistor Q1 converts the electromagnetic induction voltage, which has been converted to direct current in the
It has the function of amplifying the voltage to drive the latch circuit IC2 of the OS integrated circuit. In this embodiment, the N-channel field-effect transistor is used as the field-effect transistor Q1 in order to operate with a positive power supply. A transistor may be used.

R1 and R2 denote resistors, which have the function of supplying a bias voltage substantially equal to the gate cut-off voltage of the field effect transistor Q1.
Is divided and supplied to the gate terminal of the field effect transistor Q1. The resistors R1 and R2 preferably use resistors of about several milliohms in order to reduce power consumption.
The battery E1 preferably uses a lithium battery.

R3 is also a resistor, and is connected from the positive power supply terminal of the battery E1 to the drain terminal of the field effect transistor Q1. The source terminal of the field effect transistor Q1 is connected to the ground terminal.

When no induced voltage due to electromagnetic induction is supplied to the gate terminal of the field effect transistor Q1,
The field effect transistor Q1 is cut off and the resistance between the drain terminal and the source terminal becomes high, so that no drain current flows and the drain voltage of the field effect transistor Q1 becomes equal to the voltage of the battery E1. When an induced voltage due to electromagnetic induction is supplied to the gate terminal of the field effect transistor Q1, the resistance between the drain terminal and the source terminal decreases, and a drain current flows through the field effect transistor Q1. When a drain current flows through the field effect transistor Q1, the voltage at the drain terminal of the field effect transistor Q1 decreases due to a voltage drop caused by the resistor R3.

IC1 indicates an inverter circuit of a CMOS integrated circuit, and IC2 indicates a set / reset / latch circuit of the CMOS integrated circuit. The drain terminal of the field effect transistor Q1 is connected to the inverter circuit IC1, and the inverter circuit IC1 is set / reset.
It is connected to the set terminal of the latch circuit IC2. As a result, the input from the drain terminal of the field effect transistor Q1 is logically inverted and input to the set terminal of the set / reset latch circuit IC2.

When the drain voltage of the field effect transistor Q1 drops and falls below the threshold voltage of the inverter circuit IC1, the set / reset latch circuit IC2 is set, and the inverted output of the set / reset latch circuit IC2 becomes "0". It becomes a logic voltage. The inverted output of the set / reset / latch circuit IC2 is connected to the gate terminal of the P-channel field-effect transistor Q2, and when the gate voltage becomes "0", the source terminal of the P-channel field-effect transistor Q2 The connection to the drain terminal is conducted, and a positive voltage is output to the drain terminal of the P-channel field effect transistor Q2. The voltage output of the P-channel field effect transistor Q2 obtained in this manner may be used as a power switch circuit connected to an electric circuit, or as a signal for driving another switch circuit.

As described above, the field effect transistor Q1
When the induced voltage due to electromagnetic induction is not supplied to the gate terminal of the transistor, the power consumption of the field effect transistor Q1 is substantially zero because the field effect transistor Q1 is in a cutoff state, and the power consumption of the P channel type field effect transistor Q2 is also zero. Becomes

As described above, since the CMOS circuit is used as the electrical switching circuit, the power consumed by the receiving section of the high-frequency electromagnetic induction switch is several microwatts or less, which is very small.

Next, the transmitting section of the high-frequency electromagnetic induction switch will be described. FIG. 2 is a circuit diagram showing a transmission unit of the high-frequency electromagnetic induction switch according to the preferred embodiment of the present invention. In FIG. 2, reference numeral 10 denotes a crystal oscillator,
Reference numeral 12 denotes a frequency divider. The crystal oscillator 10 oscillates a stable signal at a frequency that is an integral multiple of the frequency used for electromagnetic induction. Frequency divider 12 connected to crystal oscillator 10
Divides the signal oscillated from the crystal oscillator 10 to a frequency that is a fraction of an integer to obtain a signal having an electromagnetic induction frequency.

Q3 indicates a power amplifying transistor for amplifying the signal of the electromagnetic induction frequency divided by the frequency divider 12. The frequency divider 12 is connected to the base terminal of the power amplifying transistor Q3 via the resistor R4. The power amplifying transistor Q3 amplifies the power for driving the receiving unit of the high-frequency electromagnetic induction switch from a remote location.

A capacitor C3 is connected to the collector terminal of the power amplifying transistor Q3.
3, an electromagnetic induction transmission coil L3 is connected in series. The emitter terminal of the power amplifying transistor Q3 is connected to the ground terminal. The capacitance and the inductance of the capacitor C3 and the electromagnetic induction transmission coil L3 are selected so as to have a constant that resonates at a frequency used in high-frequency electromagnetic induction.

S indicates a switch. Switch S
Is used only when transmitting a high-frequency electromagnetic induction signal.
2 for supplying power from the switch S
Is turned on, the high-frequency electromagnetic induction signal is transmitted.

Reference numeral 14 denotes a booster circuit. The booster circuit 14 boosts the voltage of the battery E2 and supplies power to the power amplifying transistor Q3. By connecting the booster circuit 14, even when using a battery,
Sufficient power for a high-frequency electromagnetic induction signal can be obtained.

The choke coil L2 connected to the capacitor C3 has a sufficiently high impedance at a high frequency electromagnetic induction frequency and the power amplifying transistor Q
In order to supply a DC current to the power supply 2, one having a small DC resistance is used. C4 denotes a bus capacitor of the power supply circuit, which has a sufficiently low impedance at a high frequency electromagnetic induction frequency.

When operating the high-frequency electromagnetic induction switch constructed as described above, the switch S of the transmitting unit is turned on, and then the high-frequency electromagnetic induction transmitting coil L3 of the transmitting unit is turned on.
Is brought close to the high-frequency electromagnetic induction receiving coil L1 of the receiver. Then, the high-frequency electromagnetic induction receiving coil L1 is generated by the high-frequency electromagnetic induction transmitting coil L3.
, A high-frequency voltage is induced to output a voltage to the drain terminal of the P-channel field effect transistor Q2.

The strength of the high-frequency induction magnetic field generated by the high-frequency electromagnetic induction transmission coil L3 is reduced by the square of the distance from the coil, so that the operable distance is limited. Works well as a vessel.

The receiving part of the high frequency electromagnetic induction switch constructed as described above is attached to the water integrating meter.
Supply power only to the integrating meter part of the water integrating meter,
Turn off the power to other electrical circuits. Then, at the time of water meter reading, the transmitting unit of the high-frequency electromagnetic induction switch is brought close to the handhole in which the water volume integrating meter is housed (accordingly, the receiving unit of the high-frequency electromagnetic induction switch) to output a voltage. Power is supplied to the data transceiver that transmits and receives the integrated water volume data to transmit and receive the integrated water volume data. When the transmission / reception of the water amount integrated data is completed, the power supplies other than the water amount integrated data are cut off again.

[0030]

According to the present invention, the wireless water meter reading device can be operated for a long period of time without requiring maintenance such as battery replacement. In particular, if a general lithium battery is used, continuous operation for several years is possible.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a receiving unit of a high-frequency electromagnetic induction switch according to a preferred embodiment of the present invention.

FIG. 2 is a circuit diagram showing a transmission unit of the high-frequency electromagnetic induction switch according to the preferred embodiment of the present invention.

[Explanation of symbols]

 L1 Electromagnetic induction receiving coil C1 Capacitor D Diode Q1, Q2 Field effect transistor IC1 Inverter circuit IC2 Set / reset latch circuit L3 Electromagnetic induction transmitting coil C3 Capacitor 10 Crystal oscillator 12 Divider 14 Booster circuit

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hideaki Okino 142, Betsukai, Betsukai-cho, Notsuke-gun, Hokkaido (72) Yukio Masuda 3-2-1, Atsubetsu-minami, Atsubetsu-ku, Sapporo, Hokkaido F-term (reference) 2F031 AE09 AF04 2F073 AA07 BB01 BC01 CC01 GG02 5G057 AA01 AA05 BC01 BC03 KK02 KK12 KK23 KK41 RR10 RS05 RT01

Claims (3)

[Claims] 1. A capacitor having a capacitance that resonates with a high-frequency induction magnetic field is connected to both ends of a coil in which an elongated insulated conductor is wound in a cylindrical shape, and a capacitor is connected between one terminal of the coil and a gate terminal of a field effect transistor. A diode for converting a high-frequency voltage to a DC voltage, applying a voltage equal to the gate cutoff voltage to the field effect transistor through the one terminal of the coil, and applying a DC voltage to the drain terminal of the field effect transistor through a resistor. And connect the source terminal of the field effect transistor to the ground terminal,
A high-frequency electromagnetic induction switch comprising a receiving unit that controls an electrical switch of a CMOS integrated circuit by a change in a DC voltage at a drain terminal of a field-effect transistor due to a change in a high-frequency induction magnetic field. 2. An electric switch of the CMOS integrated circuit, comprising: an inverter circuit connected to the field effect transistor; a set / reset latch circuit having the inverter circuit connected to a set terminal;
A second field-effect transistor having an inverted output of the latch circuit connected to the gate terminal, and a voltage output to a drain terminal of the second field-effect transistor,
The high-frequency electromagnetic induction switch according to claim 1, wherein the signal serves as a signal for driving a power switch circuit. 3. A high frequency electromagnetic induction switch according to claim 1 or 2, wherein the receiving unit is attached to a water amount integrating meter, and a high frequency induction magnetic field induces a high frequency voltage in a coil of the receiving unit at the time of water meter reading. By outputting
A water meter reading device configured to supply power to a water meter integrated data transceiver attached to the water meter.