CN101629975A - Relay contact-voltage measuring and conditioning circuit and measuring method - Google Patents

Abstract

The invention discloses a measuring and conditioning circuit and a method. The circuit comprises five channels: a channel VCOMOut: the voltage of a COM terminal signal is sequentially amplified by a COM terminal protection/ filter circuit and an amplifying circuit and is sent to a data acquisition module for A/D conversion; a channel VNCOut': the voltage of an NC terminal signal is firstly attenuated by one third by voltage division and is sent to the data acquisition module for the A/D conversion by an NC protection/filter circuit and finally a follower; a channel VNCOut: the voltage of the NC terminal signal is firstly attenuated by one third by the voltage division, is amplified by an NC protection/filter circuit and finally an amplifying circuit and is sent to a data acquisition module for the A/D conversion; a channel VNOOut': an NO terminal signal is firstly attenuated by one third by the voltage division and is sent to a data acquisition module for the A/D conversion by an NO protection/filter circuit and finally the follower; a channel VNOOut: and the NC terminal signal is firstly attenuated by one third by the voltage division, is amplified by an NO protection/filter circuit and finally an amplifying circuit and is sent to the data acquisition module for the A/D conversion. The invention also discloses calibrating and measuring methods of each channel. The circuit and the methods are compatible with a normally opened relay, a normally closed relay and a conversion-type relay, select the anode terminal of a load power supply as a reference terminal of a measuring circuit in contact voltage measurement so as to reduce a measured common-mode voltage and improve the precision of the contact voltage measurement by filtration, amplification, attenuation, grading test and multi-channel test.

Description

A kind of relay contact-voltage measuring and conditioning circuit and measuring method

Technical field

The present invention relates to and measures and the control field especially a kind of relay contact-voltage measuring and conditioning circuit and measuring method.

Background technology

Relay durability test in the past all is that relay manufacturer adopts the bench teat instrument combination to measure, or ownly develops automanual measuring equipment and combine with desk-top instrument and measure.Because measuring technique in the past falls behind, measuring accuracy is not high.Along with the continuous development of science and technology, more and more higher to the relay performance requirement, also more and more higher to the requirement of testing apparatus, means of testing in the past can not satisfy the production of high-performance relay far away, has not caught up with science and technology developing steps fast.

Summary of the invention

The objective of the invention is that existing relay contact-voltage measuring is backward in technique, measuring accuracy is low in order to solve.The relay contact-voltage measuring and conditioning circuit and the measuring method that the invention provides a kind of measuring accuracy height, be applicable to automatic measurement, easily expand.

Wherein this measurement modulate circuit comprises 5 passages altogether:

Passage VCOMOut:COM end signal holds protection/filtering circuit and amplifying circuit with voltage amplification by COM successively, and carries out the A/D conversion with giving data acquisition module after the voltage amplification;

Passage VNCOut ': the NC end signal at first by dividing potential drop, makes that voltage attenuation is 1/3, then by NC protection/filtering circuit, carries out the A/D conversion by giving data acquisition module behind the follower at last;

Passage VNCOut:NC end signal makes that at first by dividing potential drop voltage attenuation is 1/3, then by NC protection/filtering circuit, gives data acquisition module after with voltage amplification by amplifying circuit at last and carries out A/D and change;

Passage VNOOut ': the NO end signal at first by dividing potential drop, makes that voltage attenuation is 1/3, then by NO protection/filtering circuit, carries out the A/D conversion by giving data acquisition module behind the follower at last;

Passage VNOOut:NC end signal makes that at first by dividing potential drop voltage attenuation is 1/3, then by NO protection/filtering circuit, gives data acquisition module after with voltage amplification by amplifying circuit at last and carries out A/D and change.

Wherein, the NC end protection/filtering circuit of forming by Rv1 and C1; The COM that is made up of Rv2 and C2 holds protection/filtering circuit; The NO end protection/filtering circuit of forming the NO end by Rv3 and C3;Resistance R 1 and R2 are NC end divider resistance, and the voltage attenuation that NC is held is 1/3;Resistance R 3 and R4 are NO end divider resistance, and the voltage attenuation that NO is held is 1/3; Diode D1 and D2 protect metering circuit with NC end voltage after partial clamper in the contact between ground reference and measuring junction negative supply; Diode D3 and D4 protect metering circuit with NO end voltage after partial clamper in the contact between ground reference and measuring junction negative supply; Operational amplifier U1 is as follower, and operational amplifier U2 is as follower, and operational amplifier U3 and peripheral resistance are formed amplifying circuit, and operational amplifier U4 and peripheral resistance are formed amplifying circuit, and operational amplifier U5 and peripheral resistance are formed amplifying circuit.

This measurement modulate circuit comprises the measurement input interface, is used to connect COM, NC and the NO end of relay.

Before the measurement modulate circuit is used for measuring, need gather path to each and calibrate one by one, least square method is adopted in calibration; Choose the measurement point of some in measurement range, during the calibration of COM end, when adding standard straight stream signal, the high termination of standard signal is measured ground, low termination COM; When NC or the calibration of NO end, when adding standard straight stream signal, the high termination COM end of signal, low termination NC or NO, each measurement point is gathered a measured value; If VNCOut, VNCOut ', VCOMOut, VNOOut, the corresponding ch0～ch4 that gathers of VNOOut ' then can obtain the parameter k of each passage and b (k0～k4 and b0～b4), wherein each passage by calibration;

$k=\frac{\underset{i=1}{\overset{11}{\mathrm{\Σ}}}{x}_i\underset{i=1}{\overset{11}{\mathrm{\Σ}}}{E}_i-11\×\underset{i=1}{\overset{11}{\mathrm{\Σ}}}{x}_i{E}_i}{{\left(\underset{i=1}{\overset{11}{\mathrm{\Σ}}}{E}_i\right)}^2-11\underset{i=1}{\overset{11}{\mathrm{\Σ}}}{E_i}^2}$

$b=\frac{\underset{i=1}{\overset{11}{\mathrm{\Σ}}}{x}_i{E}_i\underset{i=1}{\overset{11}{\mathrm{\Σ}}}{E}_i-\underset{i=1}{\overset{11}{\mathrm{\Σ}}}{x}_i\underset{i=1}{\overset{11}{\mathrm{\Σ}}}{E_i}^2}{{\left(\underset{i=1}{\overset{11}{\mathrm{\Σ}}}{E}_i\right)}^2-11\underset{i=1}{\overset{11}{\mathrm{\Σ}}}{E_i}^2}$

In the formula: the standard value of i signaling point input of Ei;

Measured value on i signaling point of Xi;

The slope of k fitting a straight line;

The intercept of b fitting a straight line.

If the data of VNCOut, VNCOut ', VCOMOut, VNOOut, VNOOut ' are respectively Vnc, Vnc ', Vcom, Vno, Vno ', establish contact voltage to be measured and be respectively Vcom, Vc and Vo; Computing machine can obtain contact voltage to be measured according to the parameter k0～k4 and the b0～b4 of data Vnc, Vnc ', Vcom, Vno, Vno ' and each passage gathered:

Wherein the COM end is (Vcom-b2)/k2;

When Vnc ' 〉=200mV, the voltage of normally closed contact calculates the value of using Vnc ', then Vc=((Vnc '-(Vcom-b2)/k2)-b1)/k1;

When Vnc '＜200mV, the voltage of normally closed contact calculates the value of using Vnc, then Vc=((Vnc-(Vcom-b2)/k2)-b0)/k0;

When Vno ' 〉=200mV, the voltage of normal contact calculates the value of using Vno ', then Vc=((Vno '-(Vcom-b2)/k2)-b4)/k4;

When Vno '＜200mV, the voltage of normally closed contact calculates the value of using Vno, then Vc=((Vnc-(Vcom-b2)/k2)-b3)/k3.

When this relay contact-voltage circuit of application is measured, because the anode of selecting load power source is as the reference ground of measuring, common mode voltage when measuring is reduced, do not need to use complicated resistance pressure-dividing network like this, help eliminating the influence that load current brings too greatly, thereby improve the precision of measuring.

When this relay contact-voltage circuit of application was measured, clamp diode and voltage dependent resistor (VDR) were carried out front-end protection, relay is switched the voltage overshoot that produces suppress, and will measure the input voltage clamper between ground reference and measuring junction negative supply voltage

When this relay contact-voltage circuit of application is measured, every group of contact COM terminal voltage amplified collection again, NO or NC terminal voltage are used two passage collections respectively because measurement range is wide, promptly a passage collection is through the signal after amplifying, signal after a passage collection decays, choose the value that suitable channel value deducts COM by software at last, obtain the contact drop or the open-circuit voltage of normally opened contact or normally closed contact, 5 passages in every group of contact are measured simultaneously.Adopt the stepping multi-channel measurement like this, can improve the precision of measurement widely, use more high-precision acquisition module and carry out the software correction, will obtain higher measuring accuracy.

Description of drawings

The present invention is described in further detail below in conjunction with accompanying drawing.

Fig. 1 is the synoptic diagram of the relay of measurement;

Fig. 2 relay contact-voltage measuring circuit block diagram of the present invention;

Fig. 3 is embodiment of relay contact-voltage measuring circuit.

Embodiment

Disclosed all features in this instructions, or the step in disclosed all methods or the process except mutually exclusive feature and/or step, all can make up by any way.

Disclosed arbitrary feature in this instructions (comprising any accessory claim, summary and accompanying drawing) is unless special narration all can be replaced by other equivalences or the alternative features with similar purpose.That is, unless special narration, each feature is an example in a series of equivalences or the similar characteristics.

Is the type synoptic diagram of three kinds of measured relay measuring as Fig. 1, for the conversion hysteria relay, when coil applies operating voltage, COM and NO connect, product coil outage, COM and NC connection; For the open type relay, when coil applied operating voltage, COM and NO termination were logical, and during the product coil outage, COM and NO end disconnect; For the closed type relay, when coil applied operating voltage, COM and NC end disconnected, and during the product coil outage, COM and NC termination are logical.

Fig. 2 is the relay contact-voltage measuring theory diagram, and upper part is the test loop of measured relay among the figure, and lower part is the contact-voltage measuring block diagram.The measured relay support supports with three contacts (being common port COM, Chang Kaiduan NO, normal-closed end NC) to be many groups contact relay test of one group, a load power source power supply.In Fig. 2, upper part shows position and the test philosophy block diagram of measured relay in test circuit of the coil in one six groups contacts, NO end after load current is connected through the COM end process of every group of contact by the load power source anode or NC end flow to the pull-up resistor in the pull-up resistor case, I1, I2, Pang I6 are load current, organize contact in turn more and analogize.Lower part is the instrumentation plan of 3 contacts of one group of contact among Fig. 2, every group of contact provides 3 connector terminals (being COM end, NO end, NC end), during measurement, adopting the anode of load power source is the reference edge of measuring system, common mode voltage in reducing like this to measure, with respect to the anode of load power source, the magnitude of voltage of each COM, NC, NO contact is negative, and the anode of load power source is connected to the power supply of metering circuit with reference to ground.During measurement, tested contact is connected to corresponding connector, wherein COM end is via behind overvoltage protection/filtration module, and 20 times of voltage amplifications are as passage VCOMOut.Wherein NC end is via behind overvoltage protection/filtration module, andvoltage attenuation 1/3 is divided into two branch roads then, branch road by behind the follower as passage VNCOut ', another branch voltage amplifies 50 times as passage VNCOut; Wherein the NO end is via behind overvoltage protection/filtration module;voltage attenuation 1/3; be divided into two branch roads then; article one, branch road by behind the follower as passage VNCout '; another branch voltage amplifies 50 times as passage VNCout; whole relay contact-voltage measuring circuit comprises VCOMOut, VNCOut ', VNCOut, VNCout ' and VNCout totally 5 passages, sends into computing machine after the signal of 5 passages is changed by capture card A/D and handles.Wherein computing machine is used for the signal of gathering is handled.

Fig. 3 is one of specific embodiment of the invention, the measurement modulate circuit schematic diagram of the one group of contact of having drawn, and each device and circuit theory are described below among the figure: P1 provides interface for measuring input, is used to connect COM, NC and the NO end of relay.Wherein Rv1, Rv2, Rv3 are voltage dependent resistor (VDR), shield, and the influence that the back electromotive force in the time of can effectively preventing the actuating of relay brings, the effect ofcapacitor C 1, C2, C3 are to filter the high fdrequency component that is added in the load power source of two ends, contact.Wherein the NC of Rv1 and C1 composition holds protection/filtering circuit.Wherein the COM of Rv2 and C2 composition holds protection/filtering circuit.Wherein Rv3 and C3 form the NO end protection/filtering circuit of NO end.Wherein resistance R 1 and R2 are NC end divider resistance, and the voltage attenuation that NC is held is 1/3; Whereinresistance R 3 and R4 are NO end divider resistance, and the voltage attenuation that NO is held is 1/3.Wherein diode D1 and D2 protect metering circuit with NC end voltage after partial clamper in the contact between ground reference and measuring junction negative supply; Wherein diode D3 and D4 protect metering circuit with NO end voltage after partial clamper in the contact between ground reference and measuring junction negative supply.Wherein operational amplifier U1 is as follower, operational amplifier U2 is as follower, operational amplifier U3 and peripheral resistance are formed 50 times of amplifying circuits, and operational amplifier U4 and peripheral resistance are formed 20 times of amplifying circuits, and operational amplifier U5 and peripheral resistance are formed 50 times of amplifying circuits.

This circuit comprises 5 passages altogether:

The COM end protection/filtering circuit that passage VCOMOut:COM end signal is formed by Rv2 and C2; by amplifying circuit with 20 times of voltage amplifications; and carry out A/D conversion with giving data acquisition module after the voltage amplification, wherein the voltage measurement scope of COM end be 0～-500mV.

Passage VNCOut ': the NC end signal is at first by R1 and R2 dividing potential drop; make that voltage attenuation is 1/3; NC protection/the filtering circuit of forming by Rv1 and C1 then carries out A/D and changes by giving data acquisition module behind the follower at last, and this channel measurement scope is-600mV～-30V.

Passage VNCOut:NC end signal is at first by R1 and R2 dividing potential drop; make that voltage attenuation is 1/3; NC protection/the filtering circuit of forming by Rv1 and C1 then; carry out the A/D conversion by amplifying circuit with giving data acquisition module after 50 times of the voltage amplifications at last, this channel measurement scope is 0～-600mV.

Passage VNOOut ': the NO end signal is at first by R3 and R4 dividing potential drop; make that voltage attenuation is 1/3; NO protection/the filtering circuit of forming by Rv3 and C3 then carries out A/D and changes by giving data acquisition module behind the follower at last, and this channel measurement scope is-600mV～-30V.

Passage VNOOut:NC end signal is at first by R3 and R4 dividing potential drop; make that voltage attenuation is 1/3; NO protection/the filtering circuit of forming by Rv3 and C3 then; carry out the A/D conversion by amplifying circuit with giving data acquisition module after 50 times of the voltage amplifications at last, this channel measurement scope is 0～-600mV.

Wherein computing machine is finished data processing, and data processing comprises calibrate and handles and calculate.Before formal the measurement, each to be gathered path calibrate one by one, least square method is adopted in calibration, chooses the measurement point of some in measurement range, such as 11 measurement points.During the calibration of COM end, when adding standard straight stream signal, the high termination of standard signal is measured ground, low termination COM; When NC or the calibration of NO end, when adding standard straight stream signal, the high termination COM end of signal, low termination NC or NO, each measurement point is gathered a measured value.If VNCOut, VNCOut ', VCOMOut, VNOOut, the corresponding ch0～ch4 that gathers of VNOOut ' then can obtain the parameter k of each passage and b (k0～k4 and b0～b4) by calibration.Wherein k0～k4 and b0～b4 are corresponding successively with ch0～ch4.Wherein least square method is adopted in calibration.

$k=\frac{\underset{i=1}{\overset{11}{\mathrm{\Σ}}}{x}_i\underset{i=1}{\overset{11}{\mathrm{\Σ}}}{E}_i-11\×\underset{i=1}{\overset{11}{\mathrm{\Σ}}}{x}_i{E}_i}{{\left(\underset{i=1}{\overset{11}{\mathrm{\Σ}}}{E}_i\right)}^2-11\underset{i=1}{\overset{11}{\mathrm{\Σ}}}{E_i}^2}$Pang Pang Pang Pang Pang (formula 1)

$b=\frac{\underset{i=1}{\overset{11}{\mathrm{\Σ}}}{x}_i{E}_i\underset{i=1}{\overset{11}{\mathrm{\Σ}}}{E}_i-\underset{i=1}{\overset{11}{\mathrm{\Σ}}}{x}_i\underset{i=1}{\overset{11}{\mathrm{\Σ}}}{E_i}^2}{{\left(\underset{i=1}{\overset{11}{\mathrm{\Σ}}}{E}_i\right)}^2-11\underset{i=1}{\overset{11}{\mathrm{\Σ}}}{E_i}^2}$Pang Pang Pang Pang? formula 2)

In the formula: the standard value of i signaling point input of Ei;

Measured value on i signaling point of Xi;

The slope of k fitting a straight line;

The intercept of b fitting a straight line.

As calibrate a COM passage, corresponding input range 0～-500mV, in this scope, choose 11 points, calibrate as stated above, thereby obtain parameter k2 and b2.By calibration, thereby obtain k0～k4 and b0～b4 to each passage.

When measuring, the data of establishing VNCOut, VNCOut ', VCOMOut, VNOOut, VNOOut ' are respectively Vnc, Vnc ', Vcom, Vno, Vno ', establish contact voltage to be measured and are respectively Vcom, Vc and Vo.Computing machine can obtain contact voltage to be measured according to the parameter k0～k4 and the b0～b4 of data Vnc, Vnc ', Vcom, Vno, Vno ' and each passage gathered.

Wherein the COM end is (Vcom-b2)/k2;

Because NC and NO end adopt stepping to measure, and after obtaining measurement data, are performed as follows calculating:

When Vnc ' 〉=200mV, the voltage of normally closed contact calculates the value of using Vnc ', then Vc=((Vnc '-(Vcom-b2)/k2)-b1)/k1;

When Vnc '＜200mV, the voltage of normally closed contact calculates the value of using Vnc, then Vc=((Vnc-(Vcom-b2)/k2)-b0)/k0.

When Vno ' 〉=200mV, the voltage of normal contact calculates the value of using Vno ', then Vc=((Vno '-(Vcom-b2)/k2)-b4)/k4;

When Vno '＜200mV, the voltage of normally closed contact calculates the value of using Vno, then Vc=((

Vnc-(Vcom-b2)/k2)-b3)/k3。

When this relay contact-voltage circuit of application is measured, relay durability test that can compatible three types, different types only need connect corresponding binding post, for the conversion hysteria relay, the COM end is connected to the COM terminal adapter during connection, the NO end is connected to the NO terminal adapter, and the NC end is connected to the NC terminal adapter; For the open type relay, the COM end is connected to the COM terminal adapter during connection, and the NO end is connected to the NO terminal adapter, and the NC terminal adapter does not just connect; For the closed type relay, the COM end is connected to the COM terminal adapter during connection, and the NC end is connected to the NC terminal adapter, and the NO terminal adapter does not just connect.Select simultaneously, and in use corresponding passage setting to get final product in the software of measuring system.

When this relay contact-voltage circuit of application is measured, because the anode of selecting load power source is as the reference ground of measuring, common mode voltage when measuring is reduced, do not need to use complicated resistance pressure-dividing network like this, help eliminating the influence that load current brings too greatly, thereby improve the precision of measuring.

When this relay contact-voltage circuit of application was measured, clamp diode and voltage dependent resistor (VDR) were carried out front-end protection, relay is switched the voltage overshoot that produces suppress, and will measure the input voltage clamper between ground reference and measuring junction negative supply voltage

When this relay contact-voltage circuit of application is measured, every group of contact COM terminal voltage amplified collection again, NO or NC terminal voltage are used two passage collections respectively because measurement range is wide, promptly a passage collection is through the signal after amplifying, signal after a passage collection decays, choose the value that suitable channel value deducts COM by software at last, obtain the contact drop or the open-circuit voltage of normally opened contact or normally closed contact, 5 passages in every group of contact are measured simultaneously.Adopt the stepping multi-channel measurement like this, can improve the precision of measurement widely, use more high-precision acquisition module and carry out the software correction, will obtain higher measuring accuracy.

The present invention is not limited to aforesaid embodiment.The present invention expands to any new feature or any new combination that discloses in this manual, and the arbitrary new method that discloses or step or any new combination of process.

The above only is preferred embodiment of the present invention, not in order to restriction the present invention, all any modifications of being done within the spirit and principles in the present invention, is equal to and replaces and improvement etc., all should be included within protection scope of the present invention.

Claims (5)

1. the measurement modulate circuit is characterized in that, this circuit comprises 5 passages altogether:

Passage VCOMOut:COM end signal holds protection/filtering circuit and amplifying circuit with voltage amplification by COM successively, and carries out the A/D conversion with giving data acquisition module after the voltage amplification;

Passage VNCOut ': the NC end signal at first by dividing potential drop, makes that voltage attenuation is 1/3, then by NC protection/filtering circuit, carries out the A/D conversion by giving data acquisition module behind the follower at last;

Passage VNCOut:NC end signal makes that at first by dividing potential drop voltage attenuation is 1/3, then by NC protection/filtering circuit, gives data acquisition module after with voltage amplification by amplifying circuit at last and carries out A/D and change;

Passage VNOOut ': the NO end signal at first by dividing potential drop, makes that voltage attenuation is 1/3, then by NO protection/filtering circuit, carries out the A/D conversion by giving data acquisition module behind the follower at last;

Passage VNOOut:NC end signal makes that at first by dividing potential drop voltage attenuation is 1/3, then by NO protection/filtering circuit, gives data acquisition module after with voltage amplification by amplifying circuit at last and carries out A/D and change.

2. measurement modulate circuit as claimed in claim 1 is characterized in that, the NC that is made up of Rv1 and C1 holds protection/filtering circuit; The COM that is made up of Rv2 and C2 holds protection/filtering circuit; The NO end protection/filtering circuit of forming the NO end by Rv3 and C3; Resistance R 1 and R2 are NC end divider resistance, and the voltage attenuation that NC is held is 1/3; Resistance R 3 and R4 are NO end divider resistance, and the voltage attenuation that NO is held is 1/3; Diode D1 and D2 protect metering circuit with NC end voltage after partial clamper in the contact between ground reference and measuring junction negative supply; Diode D3 and D4 protect metering circuit with NO end voltage after partial clamper in the contact between ground reference and measuring junction negative supply; Operational amplifier U1 is as follower, and operational amplifier U2 is as follower, and operational amplifier U3 and peripheral resistance are formed amplifying circuit, and operational amplifier U4 and peripheral resistance are formed amplifying circuit, and operational amplifier U5 and peripheral resistance are formed amplifying circuit.

3. measurement modulate circuit as claimed in claim 1 or 2 is characterized in that, this measurement modulate circuit comprises the measurement input interface, is used to connect COM, NC and the NO end of relay.

4. as the channel calibration method of measurement modulate circuit as described in the claim 1-3, it is characterized in that each is gathered path calibrate one by one, least square method is adopted in calibration; Choose the measurement point of some in measurement range, during the calibration of COM end, when adding standard straight stream signal, the high termination of standard signal is measured ground, low termination COM; When NC or the calibration of NO end, when adding standard straight stream signal, the high termination COM end of signal, low termination NC or NO, each measurement point is gathered a measured value; If VNCOut, VNCOut ', VCOMOut, VNOOut, the corresponding ch0～ch4 that gathers of VNOOut ', then by calibration can obtain the parameter k of each passage and b (k0～k4 and b0～b4), wherein each passage:

$k=\frac{\underset{i=1}{\overset{11}{\mathrm{\Σ}}}{x}_i\underset{i=1}{\overset{11}{\mathrm{\Σ}}}{E}_i-11\×\underset{i=1}{\overset{11}{\mathrm{\Σ}}}{x}_i{E}_i}{{\left(\underset{i=1}{\overset{11}{\mathrm{\Σ}}}{E}_i\right)}^2-11\underset{i=1}{\overset{11}{\mathrm{\Σ}}}{E}_i^2}$

$b=\frac{\underset{i=1}{\overset{11}{\mathrm{\Σ}}}{x}_i{E}_i\underset{i=1}{\overset{11}{\mathrm{\Σ}}}{E}_i-\underset{i=1}{\overset{11}{\mathrm{\Σ}}}{x}_i\underset{i=1}{\overset{11}{\mathrm{\Σ}}}{E}_i^2}{{\left(\underset{i=1}{\overset{11}{\mathrm{\Σ}}}{E}_i\right)}^2-11\underset{i=1}{\overset{11}{\mathrm{\Σ}}}{E}_i^2}$

In the formula: the standard value of i signaling point input of Ei;

Measured value on i signaling point of Xi;

The slope of k fitting a straight line;

The intercept of b fitting a straight line.

5. as the channel measurement method of measurement modulate circuit as described in the claim 1-3, it is characterized in that, if the data of VNCOut, VNCOut ', VCOMOut, VNOOut, VNOOut ' are respectively Vnc, Vnc ', Vcom, Vno, Vno ', establish contact voltage to be measured and be respectively Vcom, Vc and Vo; Computing machine can obtain contact voltage to be measured according to the parameter k0～k4 and the b0～b4 of data Vnc, Vnc ', Vcom, Vno, Vno ' and each passage gathered:

Wherein the COM end is (Vcom-b2)/k2;

When Vnc ' 〉=200mV, the voltage of normally closed contact calculates the value of using Vnc ', then Vc=((Vnc '-(Vcom-b2)/k2)-b1)/k1;

When Vnc '＜200mV, the voltage of normally closed contact calculates the value of using Vnc, then Vc=((Vnc-(Vcom-b2)/k2)-b0)/k0;

When Vno ' 〉=200mV, the voltage of normal contact calculates the value of using Vno ', then Vc=((Vno '-(Vcom-b2)/k2)-b4)/k4;

When Vno '＜200mV, the voltage of normally closed contact calculates the value of using Vno, then Vc=((Vnc-(Vcom-b2)/k2)-b3)/k3.

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