CN201964897U - Wireless passive measuring circuit - Google Patents

Abstract

The utility model discloses a wireless passive measuring circuit which comprises a wireless passive sensor part and an external controller part, wherein the wireless passive sensor part consists of a capacitor and a coil, and the capacitor or the coil is a sensor which can work without a power supply. The wireless passive measuring circuit has characteristics of simplicity, small volume, light weight and the like and is particularly suitable for measuring occasions which need long time detection and in which wirings are not allowed to exist.

Description

A kind of metering circuit of wireless and passive

Technical field

The present invention relates to the circuit of physical quantitys such as a kind of gaging pressure, temperature, displacement, particularly relate to a kind of circuit of wireless and power free physical quantity.

Background technology

Usually, when needing pressure, displacement, the temperature of inner certain internal organs in measuring vessel inside, animal or human's body, the method for wound be can adopt, pressure, displacement, temperature sensor are about to by the lead output signal.Also can adopt wireless method.Preceding a kind of mode often is restricted by the wire transmission signal; A kind of mode in back need give sensor and wireless launcher configuration electronics supplying with power supply, thereby its volume, life-span, weight or the like all are subjected to the restriction of battery.

Summary of the invention

Technical matters to be solved by this invention is, provides a kind of when having certain distance in the space, do not need line also not need the metering circuit of the physical quantitys such as pressure, temperature to the pressure transducer power supply.

The technical solution adopted in the present invention is: a kind of wireless and passive physical quantity circuit, it is characterized in that: comprise wireless sourceless sensor part and peripheral control unit part, wherein the wireless sourceless sensor part constitutes antiresonant circuit by a capacitive transducer and a coil, or constitutes antiresonant circuit by electric capacity and inductance sensor; Peripheral control unit comprises, with the magnetic test coil of above-mentioned coil formation loosely coupled transformer, pulse excitation signal generator, resonance signal period measurement circuit, and switch, wherein this switch can make magnetic test coil switch between pulse excitation signal generator and resonance signal period measurement circuit.A kind of metering circuit of wireless and passive physical quantity, it comprises following steps: a). and switch is in first closure state, makes magnetic test coil and pulse excitation signal generator constitute the closed-loop path; B). the pulse excitation signal generator produces a pulse signal; C). constitute antiresonant circuit by loosely coupled transformer excitation capacitive transducer and coil; D). switch is switched to second closure state, make magnetic test coil and resonance signal cycle detection circuit constitute the closed-loop path; E). the oscillator signal cycle of resonance signal cycle detection circuit measuring resonant circuit; F). can obtain the measured of sensor institute sensing by calculating.

Metering circuit of the present invention, have simple in structure, with low cost, volume is little, need not advantages such as debugging.

Description of drawings

Fig. 1 is the schematic diagram of wireless and passive metering circuit of the present invention.

Fig. 2 is the schematic diagram of the wireless and passive pressure measurement circuitry of employing capacitive transducer of the present invention.

Fig. 3 is the schematic diagram of the wireless and passive displacement measurement circuit of employing inductance sensor of the present invention.

Embodiment

Below in conjunction with embodiment and accompanying drawing wireless and passive physical quantity circuit of the present invention is made a detailed description.

Embodiment one: as shown in Figure 2, wireless and passive pressure measurement circuitry of the present invention, capacitive pressure transducer C and coil L2 constitute antiresonant circuit, and coil L2 and magnetic test coil L1 constitute a loosely coupled transformer B.During measurement, be connected with the pulse excitation signal generator by the magnetic test coil L1 of K switch earlier loosely coupled transformer B, external circuit produces a pulse signal by the pulse excitation signal generator, constitute antiresonant circuit by loosely coupled transformer B excitation capacitive pressure transducer C and coil L2, by K switch the magnetic test coil L1 of loosely coupled transformer B is switched to resonance signal period measurement circuit then, measure the cycle of the oscillator signal of resonant network, and then by calculating the force value that can obtain capacitive pressure transducer institute sensing.

Computation process is:

The resonance frequency of the antiresonant circuit that capacitive transducer and coil L2 constitute is:

$f=\frac{1}{2\mathrm{\π}\sqrt{\mathrm{LC}}}$

Or

$C=\frac{1}{{\left(2\mathrm{\π}\right)}^{2}L}$

In the formula: L is the inductance value of coil L2.Promptly under the known condition of L, can calculate C by detected f.And the electric capacity of capacitive transducer:

C＝F(P)

In the formula: P is tested force value, and F (P) is the function that calculates electric capacity C.Usually, can select linearity sensor preferably, thereby the funtcional relationship of following formula can be rewritten as again

C＝kP+C ₀

In the formula: k is a sensitivity coefficient, C ₀0 point value for capacitive transducer.Or following formula is rewritten as

P＝βC+P ₀

In the formula: β=1/k is a sensitivity coefficient, P ₀=-C ₀/ k is 0 point value of capacitive transducer.Can calculate tested pressure value P at last.

Embodiment two: as shown in Figure 3, wireless and passive displacement measurement circuit of the present invention, capacitor C and inductance displacement sensor L2 constitute antiresonant circuit, and inductance displacement sensor L2 and magnetic test coil L1 constitute a loosely coupled transformer B.During measurement, be connected with the pulse excitation signal generator by the magnetic test coil L1 of K switch earlier loosely coupled transformer B, external circuit produces a pulse signal by the pulse excitation signal generator, constitute antiresonant circuit by loosely coupled transformer B excitation capacitor C and inductance displacement sensor L2, by K switch the coil L1 of loosely coupled transformer B is switched to resonance signal period measurement circuit then, measure the cycle of the oscillator signal of resonant network, and then by calculating the shift value that can obtain inductance displacement sensor institute sensing.

The resonance frequency of the antiresonant circuit that capacitor C and inductance displacement sensor L2 constitute is:

$f=\frac{1}{2\mathrm{\π}\sqrt{\mathrm{LC}}}$

Or

$L=\frac{1}{{\left(2\mathrm{\π}\right)}^{2}C}$

In the formula: promptly under the known condition of C, can calculate L by detected f.And the inductance value of displacement inductance sensor L2:

L＝F(X)

In the formula: X is tested shift value, and F (X) is the function that calculates inductance value L.Usually, can select linearity sensor preferably, thereby the funtcional relationship of following formula can be rewritten as again

L＝kX+L ₀

In the formula: k is a sensitivity coefficient, L ₀0 point value for inductance displacement sensor.Or following formula is rewritten as

X＝βL+T ₀

In the formula: β=1/k is a sensitivity coefficient, X ₀=-L ₀/ k is 0 point value of inductance displacement sensor.Can calculate tested shift value X at last.

Claims (6)

1. wireless and passive metering circuit is characterized in that: comprise wireless sourceless sensor part and peripheral control unit part,

Wherein the wireless sourceless sensor part constitutes antiresonant circuit by a capacitive transducer and a coil;

Peripheral control unit partly comprises, magnetic test coil with above-mentioned coil formation loosely coupled transformer, the pulse excitation signal generator, resonance signal period measurement circuit, and switch, wherein this switch can make magnetic test coil switch mutually between pulse excitation signal generator and resonance signal period measurement circuit.

2. wireless and passive metering circuit according to claim 1 is characterized in that: wherein this switch is a double-point double-throw switch.

3. wireless and passive metering circuit according to claim 1 and 2 is characterized in that: wherein this capacitive transducer is a capacitive pressure transducer.

4. wireless and passive metering circuit is characterized in that: comprise wireless sourceless sensor part and peripheral control unit part,

Wherein the wireless sourceless sensor part constitutes antiresonant circuit by an electric capacity and an inductance sensor;

Peripheral control unit partly comprises, magnetic test coil with above-mentioned inductance sensor formation loosely coupled transformer, the pulse excitation signal generator, resonance signal period measurement circuit, and switch, wherein this switch can make magnetic test coil switch mutually between pulse excitation signal generator and resonance signal period measurement circuit.

5. wireless and passive metering circuit according to claim 4 is characterized in that: wherein this switch is a double-point double-throw switch.

6. according to claim 4 or 5 described wireless and passive metering circuits, it is characterized in that: wherein this inductance sensor is an inductance displacement sensor.

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