CN1139793C - Multi-parameter sensor for micro-power optical fibre transmission - Google Patents

Abstract

The present invention relates to a multi-parameter sensor with low power consumption for optical fiber transmission, which has the structure that a detecting sensitive element comprises a differential capacitor and a semiconductor thermosensitive resistor, and meantime, a power supply voltage stabilizing circuit with micro power consumption is added, which solves the problem of unstability of sending signals. The differential capacitor is formed by the fusing of three welding rings and five metal assemblies to form a shared electrode grounding mode of the differential capacitor. A signal conversion circuit uses a pulse-width coding modulation technology to increase three to eight transmission parameters of an optical fiber from the original two transmission parameters, which solves the problem of temperature compensation of the sensor. A trigger is used for converting the pulse width of the capacitor in view of the characteristics of the contact of the shared electrode grounding of the differential capacitor and measuring media.

Description

Multi-parameter sensor for micro-power optical fibre transmission

The present invention relates to automation process control and use the thermal measurement instrument, belong to little power consumption Optical Fiber Transmission multiparameter variable differential capacitance type differential pressure or pressure, temperature sensor specifically.

A large amount of on-the-spot differential pressure/pressure, temperature measuring instrument that existing automation field uses, one class is a pneumatic instrument, variation with air pressure transmits information measured, one class is to use the electric signal that changes by analog quantity to transmit information measured, and a class is to use the electric signal that changes by digital quantity to transmit information measured.All need to consume the more energy during above-mentioned three class instrumentations, general power supply is the power consumption of 30～40mw, and transmission manner has that pipeline transmission, lead transmit, the radio modulation emission transmits.In order to reach the little power consumption work below the 0.7mw, take light signal to send in-site measurement information with the photoconduction transmitting fiber tow, once there was the patent No. 95223991.4 to introduce the Optical Fiber Transmission luminous power and promoted little power consumption differential pressure pick-up, send in actual applications and have more problem, particularly it is applied in differential capacitive structure, its common electrode need connect shell, the contacted sensor of the earth and measured medium adopts this patent, circuit can't make measured value stable, under external interference, can cause the blocking of oscillator, the output of sensor no signal, but adopt differential capacitive structure, can't accomplish that common electrode and measured medium and the earth are isolated, therefore adopt this patented technology can't produce product.This patented technology simultaneously, only can transmit the single channel pressure signal an optical-fibre channel, can't transmit signal synthesis such as multiparameter such as temperature, pressure, differential pressures, therefore also can't compensate and correct temperature performance, change in voltage is big in the luminous power change-over circuit of its transmitting terminal in addition, cause and send the data instability, measuring error is increased, poor stability in the demodulator circuit of its receiving end, circuit parameter needs often to adjust, and therefore can't use in the differential capacitive sensor of public electrode ground connection.

The purpose of this invention is to provide same optical fiber and carry out the multiparameter information transmission, it is stable to be used for its measured value of the contacted sensor of the earth and measured medium, keep the circuit of transmitting terminal and receiving end stable simultaneously, can adapt to a kind of multi-parameter sensor for micro-power optical fibre transmission of differential capacitive sensor with public electrode ground connection.

For finishing the technical scheme that above-mentioned purpose is taked: differential capacitor measurement of film thickness head is middle by both sides isolation diaphragm assembly to be insulation course, the centre of insulation course is a fixed capacity pole plate extension line by shared capacitor plate and both sides, middle filling silicon oil, above-mentioned isolation diaphragm assembly, shared capacitor plate, electric capacity seat are welded into three weld-rings and form, differential capacitor measurement of film thickness head is established web member and is connected with flange, and connect converting member by web member again, converting member connects control box by optical fiber, wherein is provided with by light emitting diode D in the converting member ₂It is elementary to connect transformer B, and next level connects stabilivolt Z ₁～Z ₆, diode D ₃, resistance R ₅～R ₆, capacitor C ₂With electric capacity E ₁～E ₃The light of forming promotes power supply generative circuit 16 and reaches by differential capacitor C _H, C _LWith thermistor R _TPass through R respectively ₁₀, R ₉And capacitor C ₄Connect integrated package U ₁CD4013 and U ₂The d type flip flop of CD4013 connects reverser U simultaneously ₅4069 and U ₆, U ₇The CD4051 analog switch, U ₆And U ₇Other connects oscillatory circuit U ₃CD4069 and timing circuit U ₄CD4069 and R ₁₄, R ₇～R ₈And C ₃, U ₇Other connects U ₈MC14528 and U ₉CD4071 and R ₁₁～R ₁₂And C ₅～C ₆U wherein ₉Connect triode T ₃, luminous fine diode D ₄, resistance R ₁₃The coded modulation circuit is surveyed in the signal danger of forming, and connects optical fiber, deliver to control box by optical fiber, and above-mentioned control box is interior by resistance R ₁, R ₂And capacitor C ₁Connect integrated package six reverser square-wave oscillator U respectively ₁₄CD4069 passes through R ₃And R ₄Connect triode T ₂And laser diode D ₁The light of forming promotes exciting circuit and 17 by photo-detector D ₅, D ₅Connect R ₁₅And C ₇And triode T ₄, connect integrated package U through amplifying ₄And R ₁₈, C ₈And connection JK flip-flop U ₁₂CD4027, U ₁₂Signal is delivered to XOR gate electricity U ₁₃74LS89 is until CPU ₂, other delivers to CPU ₁Form measuring-signal reception Jie and mediate reason circuit 18.

The present invention adopts the differential pressure/pressure transducer of differential capacitance type structure to combine with the Fibre Optical Communication Technology that special benefits is arranged, and can in same optical fiber, adopt width modulation, pulse code, the method that the arteries and veins position sends, the requirement that little power consumption is transmitted and reached to the realization parameter has promotional value, can use up the promotion method comes sensor that the energy is provided, also power supply is made from charged pool in available sensors inside, have very big dirigibility and security, be applicable to inflammable and explosive Medium Measurement and occasion, more can be applicable to the environment of strong electromagnetic radiation, the present invention can abandon complicated controller switching equipment in addition, and carries the lithium battery work that meets the Sefe antiexplosion requirement by in the instrument.

The embodiment of the invention is described in detail in conjunction with the accompanying drawings.

Fig. 1 structural drawing of the present invention;

Fig. 2 sensor differential capacitor of the present invention measurement of film thickness header structure figure;

Fig. 3 input coded modulation of the present invention circuit diagram;

Fig. 4 light of the present invention promotes power supply generative circuit figure;

Fig. 5 light of the present invention promotes exciting circuit figure;

Fig. 6 measuring-signal of the present invention receives to be situated between mediates the reason circuit diagram.

According to illustrated in figures 1 and 2, by being insulation course 11 in the middle of the both sides isolation diaphragm assembly 7, the centre of insulation course 11 by shared capacitor plate 10 and both sides be fixed capacity pole plate 9, extension line 8 in the middle of it filling silicon oils 12, isolation diaphragm assembly 7, shared capacitor plate 10, electric capacity seat 13 be welded into the differential capacitor measurement of film thickness that three weld-rings 14 form 1.Its shared capacitor plate 10 constitutes two capacitors with the fixed capacity pole plate 9 and the middle silicone oil of filling 12 of its both sides, and the high-pressure side is a capacitor C _H, low pressure is surveyed capacitor C _L, extraneous tested pressure P ₁, P ₂Act on the spacer of both sides, transmit pressure by silicone oil 12 and act on the shared capacitor plate 10, make shared capacitor plate 10 produce displacement, make C _HWith C _LElectric capacity change, by detecting C _HAnd C _LElectric capacitance change can measure P ₁With P ₂Difference, differential capacitor is directly contacted with measured medium and the earth by three weld-rings 14, so mode is delivered to input coded modulation circuit 15 with pressure and temperature measurement signal, as shown in Figure 3, U ₁, U ₂(can increase on demand) is the pulse width detection circuit of d type flip flop (CD4013) formation sensor, sensing element C _H, C _L, R _TConstitute the timing element of the RC charging and discharging circuit of d type flip flop, when these component parameters were measured effect of signals and changed, then the RC charging rate of d type flip flop changed.By U ₆Under the effect of output pulse, corresponding d type flip flop output terminal becomes high level, is charged in the RC loop.When the charging level on the C reaches a certain value, because an end in RC loop is continuous with the reset terminal of d type flip flop, therefore, make the d type flip flop upset, output becomes low level.The width of pulse and the parameter correlation of sensing element.The pulse of d type flip flop is by U ₃The time clock that reverser (CD4069) constitutes is as U ₄The count pulse of counter (CD40193), counter can be arranged to scale-of-eight (or 16 systems are decided on d type flip flop quantity) working method on demand, and its output end signal is as U ₆, U ₇The control signal of eight path analoging switch (CD4051) drives corresponding switch motion.Because at analog switch U ₆Public termination high level, so the output switching terminal mouth at gating can produce a positive pulse, its time that continues is depended on the frequency of time clock, this positive pulse will trigger the corresponding D trigger, make the output terminal of this d type flip flop produce the positive pulse that depends on the RC network parameter that connects, its pulsewidth has been represented the size of measured signal.Because U ₇Gating port and U ₆The output port of the d type flip flop of corresponding gating port links to each other, so at U ₇Common port obtain to press counter U ₄Control timing connects the pulse train that each d type flip flop produces, and the start bit of this pulse train can be by counter U ₄Control produces a specific identification pulse, forms coded pulse group (U ₇Function also can be finished with OR circuit).

Through U ₇The coded pulse group of common port output is via U ₈(MC14528) and the 3.5us pulsewidth that constitutes of outward element RC respectively by front and back along two monostalbe triggers that trigger, convert each pulse width signal to two narrow pulse signals, its time interval equals the width of former pulse width signal.Two monostalbe triggers output burst pulse is delivered to OR circuit U ₉(CD4071) input end is at U ₉Output terminal formed coding burst pulse group driving LED light emitting diode D ₄Change light pulse into, be sent to the pulpit secondary instrument through light transmitting fiber 5.

As shown in Figure 4, the light-pulse generator that is transmitted by optical fiber 5 is through D ₂After silicon photocell receives, produce pulsating dc voltage, it is elementary to deliver to step-up transformer B, and level produces higher pulsating dc voltage secondarily, through D ₃Rectification, R ₅, Z ₅, Z ₆, voltage stabilizing, electric capacity E ₁, C ₂, E ₂, E ₃, form direct supply after the filtering for other circuit function.

Promotion exciting circuit in control box 6 as shown in Figure 5, U ₁₄CD4069 is that six reversers constitute square-wave oscillator, exports triode T to through shaping ₁And T ₂The complex pipe driving laser diode D that constitutes ₁, the output light-pulse generator is coupled to optical fiber 5 and transmits spot sensor.And for example shown in Figure 6, by the light pulse signal of optical fiber 5 transmission through photo-detector D ₅, change electric impulse signal into, deliver to transistor T ₄Base stage, through being amplified in its collector output encoder burst pulse group, deliver to by U ₁₁The monostalbe trigger of the 5us pulse front edge triggering that (CD4047) constitutes with pulse strenching, is delivered to by U ₁₂(CD4027) JK flip-flop is at JK flip-flop U ₁₂Q and

End just can demodulate coded pulse group signal or its reversed phase signal, and these two signals can directly send the INTO of CPU1, fracture among the INT1, through CPU1 to the counting computing of pulse width signal, just can obtain corresponding measured value.Also can be with U ₁₂The Q end signal is delivered to by U ₁₃(74LS86) NOR gate circuit is via the polarity orientation circuit that constitutes with two XOR gate and RC circuit, at U ₁₃Output terminal 6 pin can obtain the single polar signal identical with modulation signal, for computing machine or other circuit application.

Claims (5)

1, a kind of multi-parameter sensor for micro-power optical fibre transmission of forming by differential pressure pick-up, temperature detection sensitive element, light promotion circuit, differential capacitor measurement of film thickness head (1) is established web member (2) and is connected with mounting flange (3) also again by web member connection converting member (4), converting member (4) connects controller (6) by optical fiber (5), it is characterized in that being provided with by differential capacitor C in the described converting member (4) _H, L _LWith thermistor R _TPass through R respectively ₁₀, R ₉And capacitor C ₄Connect integrated package U ₁CD4013 and U ₂The d type flip flop of CD4013 connects reverser U simultaneously ₅CD4069 and U ₆, U ₇The CD4051 analog switch, U ₆And U ₇Connect vibration electrical equipment U in addition ₃CD4069 and timing circuit U ₄CD40193, and R ₁₄, R ₇～R ₈And C ₃, U ₇Other connects U ₈MC14528 and U ₉CD4071 and R ₁₁～R ₁₂And C ₅～C ₆, its U ₉Connect triode T ₃, light emitting diode D ₄And resistance R ₁₃Form input coded modulation circuit (15), light promotes power supply generative circuit (16), light is set in the control box (6) promotes exciting circuit (17) and measuring-signal and receive to be situated between to mediate and manage circuit (18).

2, multi-parameter sensor for micro-power optical fibre transmission according to claim 1 is characterized in that measuring-signal receives Jie and mediates reason circuit (18) by optical fiber (5) connection photo-detector D ₅, D ₅Connect R ₁₅And C ₇And triode T ₄Connect integrated package U through amplifying ₄And R ₁₈, C ₈And connection JK flip-flop U ₁₂CD4047, U ₁₂Signal is delivered to XOR social connections U ₁₃74LS86 to CPU ₂, other delivers to CPU ₁

3, multi-parameter sensor for micro-power optical fibre transmission according to claim 1, it is characterized in that differential capacitor bellows (1) is by both sides isolation diaphragm assemblies (7), the centre is insulation course (11), the centre of insulation course (11) is that fixed capacity pole plate (9) extension line 8 its middle filling silicon oils (12) are formed by shared capacitor plate (10) and both sides, and isolation diaphragm assembly (7), shared capacitor plate (10), electric capacity seat (13) are welded into three weld-rings (14).

4, multi-parameter sensor for micro-power optical fibre transmission according to claim 1 is characterized in that the Optical Fiber Transmission multi-parameter sensor, it is characterized in that light promotes power supply generative circuit (16) by light emitting diode D ₂Connect the transformer B utmost point just, next level connects stabilivolt Z ₁～Z ₆, diode D ₃, resistance R ₅And R ₆, capacitor C ₂Electric capacity E ₁～E ₃Form.

5, multi-parameter sensor for micro-power optical fibre transmission according to claim 1 is characterized in that light promotes exciting circuit (17) by R ₁～R ₂And C ₁Connect integrated package six reversers respectively and constitute square-wave oscillator U ₁₄CD4069 passes through R ₃And R ₄Connect triode T and light emitting diode D ₁Form.

Images