CN110617841A - Resistive sensor array reading circuit based on two-wire system equipotential method - Google Patents

Resistive sensor array reading circuit based on two-wire system equipotential method Download PDF

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Publication number
CN110617841A
CN110617841A CN201810635406.5A CN201810635406A CN110617841A CN 110617841 A CN110617841 A CN 110617841A CN 201810635406 A CN201810635406 A CN 201810635406A CN 110617841 A CN110617841 A CN 110617841A
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line
column
resistive sensor
row
sensor array
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赵莉民
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Long Yao Electronic Technology (jiangsu) Co Ltd
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Long Yao Electronic Technology (jiangsu) Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
    • G01D5/16—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying resistance

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  • General Physics & Mathematics (AREA)
  • Transforming Light Signals Into Electric Signals (AREA)

Abstract

The invention discloses a resistive sensor array reading circuit based on a two-wire system equipotential method, and belongs to the technical field of sensors. The sensing circuit of the invention being directed to sharing row and column linesM×NA two-dimensional resistive sensor array, comprising: the circuit comprises a current feedback operational amplifier, a column line driving operational amplifier, a row multiplexer, a column multiplexer, a test current setting resistor, a reference voltage source and two connecting wires which are respectively arranged for each row line and column line of the resistive sensor array. The invention also discloses a reading method of the reading circuit and a sensing system. Compared with the prior art, the method takes a two-wire system equipotential method as a key technology, can effectively eliminate the measurement errors generated by the lead resistance of the connecting cable, the contact resistance of the cable joint and the conduction resistance of the multi-way switch channel, and greatly improves the measurement precision of the resistive sensor array.

Description

Resistive sensor array reading circuit based on two-wire system equipotential method
Technical Field
The invention relates to the technical field of sensors, in particular to a resistive sensor array reading circuit.
Background
The array type sensing device is a device which combines a plurality of sensing elements with the same performance according to the structure of a two-dimensional array, and can change or generate corresponding forms and characteristics by detecting the change of parameters focused on the array. This feature is widely used in biosensing, temperature sensing, and thermal imaging based on infrared sensors, among others.
The resistive sensor array is widely applied to an infrared imaging simulation system, force touch sensing and temperature touch sensing. Taking the temperature sense of touch as an example, because the temperature sense sensing device involves heat transfer and temperature sensing, the device puts high requirements on temperature measurement accuracy and resolution for obtaining the thermal properties of the object, and puts high requirements on spatial resolution capability for further obtaining the thermal properties represented by different position materials of the object.
The quality or resolution of a resistive sensor array needs to be increased by increasing the number of sensors in the array. However, as the size of the sensor array increases, information acquisition and signal processing for all components becomes difficult. Typically, all of the resistive sensors of an M x N array are accessed individually, each resistive sensor having two ports, requiring 2 x M x N connecting wires. The connection mode not only has complex connection, but also can only select a single resistor to be tested each time, and has slow scanning speed, long period and low efficiency. To reduce the complexity of device interconnections, researchers have proposed two-dimensional array structures that share row and column lines. FIG. 1 shows the structure of a two-dimensional resistive sensor array sharing row and column lines. As shown in FIG. 1, the sensor array includes two sets of orthogonal lines as common row lines and common column lines, respectivelyM×NThe two-dimensional structure of the physical quantity sensitive resistor (i.e. resistive sensor) array is distributed, one end of each physical quantity sensitive resistor in the array is connected with a corresponding row line, the other end is connected with a corresponding column line, each resistor in the array has a unique combination of the row line and the column line and is positioned at the second positioniGo to the firstjFor resistance of the columnR ij It is shown that, among others,Min the case of the number of rows,Nis the number of columns. With such a structure, can be made as followsM×NOf the two-dimensional structure of (2) only requiresM+NThe number of wires ensures that any one particular resistive element can be accessed by controlling the corresponding combination of row and column lines, and therefore the number of wires required is greatly reduced.
The resistance sensor array sharing the row column line generally needs to be connected with a reading circuit through a long cable, lead resistors exist on a plurality of leads of the long connecting cable, the resistance values of the lead resistors are basically the same among a plurality of leads made of equal-length materials and increase along with the increase of the length of the cable, contact resistors exist between a plug and a socket of the connecting cable, for each pair of the contact points, the resistance values of the contact resistors change within a certain range (about 0 ~ 3 omega) along with different contact states (the contact states of the contact points change along with time, mechanical vibration and the like), the lead resistors with basically the same resistance values and the contact resistors with different resistance values have obvious influence on the testing accuracy of the resistance sensor array.
Disclosure of Invention
The technical problem to be solved by the invention is to overcome the defects of the prior art, and provide a resistive sensor array reading circuit based on a two-wire system equipotential method, which can effectively eliminate the measurement errors generated by testing the lead resistance of a cable, the contact resistance of a cable joint and the conduction resistance of a multi-way switch channel, and greatly improve the measurement precision of a resistive sensor array.
The invention specifically adopts the following technical scheme to solve the technical problems:
resistive sensor array read-out circuit based on two-wire system equipotential method, wherein the resistive sensor array shares row wires and column wiresM×NA two-dimensional resistive sensor array; wherein the readout circuit comprises: the circuit comprises a current feedback operational amplifier, a column line driving operational amplifier, a row multiplexer, a column multiplexer, a test current setting resistor, a reference voltage source and two connecting wires which are respectively arranged for each row line and column line of the resistive sensor array; the output end of the current feedback operational amplifier is connected with the non-inverting input end of the column line driving operational amplifier, the non-inverting input end of the current feedback operational amplifier is connected with zero potential, and one end of the test current setting resistor is connected withA reference voltage source; the column multiplexer can enable any one column line in the resistive sensor array to be connected with the output end of the column line driving operational amplifier through one connecting line of the column line multiplexing selector, and to be connected with the inverting input end of the column line driving operational amplifier through the other connecting line of the column line multiplexing selector, and simultaneously enables each other column line in the resistive sensor array to be respectively connected with a zero potential through the two connecting lines of the resistive sensor array; the line multiplexer can enable any one line in the resistive sensor array to be connected with the inverted input end of the current feedback operational amplifier through one connecting line, and connected with the other end of the test current setting resistor through the other connecting line, and meanwhile, each other line in the resistive sensor array is respectively connected with zero potential through the two connecting lines.
Preferably, the row multiplexer comprises a resistive sensor arrayMWith one-to-one correspondence of strips and linesMA plurality of double pole double throw switches; for each double-pole double-throw switch, one pair of common ends of the double-pole double-throw switch are respectively connected with the corresponding row line through two connecting lines of the row line, one pair of independent ends of the double-pole double-throw switch are respectively connected with the inverted input end of the current feedback operational amplifier and the other end of the test current setting resistor, and the other pair of independent ends of the double-pole double-throw switch are both connected with zero potential.
Preferably, the column multiplexer comprises a resistive sensor arrayNWith one-to-one correspondence of row and column linesNA row of double pole double throw switches; for each column double-pole double-throw switch, a pair of common ends of the column double-pole double-throw switch is respectively connected with the column line through two connecting wires of the corresponding column line, one pair of independent ends of the column double-pole double-throw switch is respectively connected with the output end of the column line driving operational amplifier and the inverted input end of the column line driving operational amplifier, and the other pair of independent ends of the column double-pole double-throw switch is connected with zero potential.
As for any resistive sensor to be tested in the resistive sensor array, the method for reading out the readout circuit according to any of the above technical solutions firstly gates the resistive sensor to be tested, specifically as follows: the column line where the resistive sensor to be tested is located is connected with the output end of the column line driving operational amplifier through one connecting line of the column line multiplexer, and the column line driving operational amplifier is connected with the output end of the column line driving operational amplifier through the column multiplexerThe other connecting wire is connected with the inverting input end of the column line driving operational amplifier, and simultaneously, each other column line in the resistive sensor array is respectively connected with a zero potential through the two connecting wires; meanwhile, a row line where the resistive sensor to be tested is located is connected with the inverted input end of the current feedback operational amplifier through one connecting line of the row multiplexer, and is connected with the other end of the test current setting resistor through the other connecting line of the row multiplexer, and meanwhile, each other row line in the resistive sensor array is respectively connected with zero potential through the two connecting lines of the other row line; then, the resistance of the resistive sensor to be measured is calculated by using the following formula：
Wherein the content of the first and second substances,the feedback voltage of the output end of the operational amplifier is fed back by the current,a reference voltage provided for a reference voltage source,the potential of the resistor and the end of the row multiplexer to which it is connected is set for the test current,the resistance value of the resistor is set for the test current.
The following technical scheme can be obtained according to the same invention concept:
resistive sensor array read-out circuit based on two-wire system equipotential method, wherein the resistive sensor array shares row wires and column wiresM×NA two-dimensional resistive sensor array; wherein the readout circuit comprises: a current feedback operational amplifier and a column line driverThe device comprises a dynamic operational amplifier, a row multiplexer, a column multiplexer, a test current setting resistor, a reference voltage source and two connecting wires which are respectively arranged for each row line and column line of the resistive sensor array; the output end of the current feedback operational amplifier is connected with the non-inverting input end of the column line driving operational amplifier, the non-inverting input end of the current feedback operational amplifier is connected with a reference voltage source, and one end of the test current setting resistor is connected with a zero potential; the column multiplexer can enable any one column line in the resistive sensor array to be connected with the output end of the column line driving operational amplifier through one connecting line of the column line multiplexing selector, and to be connected with the inverting input end of the column line driving operational amplifier through the other connecting line of the column line multiplexing selector, and simultaneously enables each other column line in the resistive sensor array to be respectively connected with a reference voltage source through the two connecting lines of the resistive sensor array; the line multiplexer can enable any one of the line lines in the resistive sensor array to be connected with the inverting input end of the current feedback operational amplifier through one connecting line of the line selector, and to be connected with the other end of the test current setting resistor through the other connecting line of the line selector, and meanwhile, each of the other line lines in the resistive sensor array is respectively connected with the reference voltage source through the two connecting lines of the line selector.
Preferably, the row multiplexer comprises a resistive sensor arrayMWith one-to-one correspondence of strips and linesMA plurality of double pole double throw switches; for each double-pole double-throw switch, one pair of public ends of the double-pole double-throw switch are respectively connected with the corresponding row line through two connecting lines of the row line, one pair of independent ends of the double-pole double-throw switch are respectively connected with the inverted input end of the current feedback operational amplifier and the other end of the test current setting resistor, and the other pair of independent ends of the double-pole double-throw switch are both connected with a reference voltage source.
Preferably, the column multiplexer comprises a resistive sensor arrayNWith one-to-one correspondence of row and column linesNA row of double pole double throw switches; for each column double-pole double-throw switch, one pair of common ends of the column double-pole double-throw switch is respectively connected with the column line through two connecting wires of the corresponding column line, one pair of independent ends of the column double-pole double-throw switch is respectively connected with the output end of the column line driving operational amplifier and the inverted input end of the column line driving operational amplifier, and the other pair of independent ends of the column double-pole double-throw switch are respectively connected with the output end of the column line driving operational amplifier and the inverted input endIs connected to a reference voltage source.
As for any resistive sensor to be tested in the resistive sensor array, the method for reading out the circuit gates the resistive sensor to be tested first, specifically as follows: the method comprises the following steps that a column line where a resistive sensor to be detected is located is connected with an output end of a column line driving operational amplifier through one connecting line of the column line multipath selector, and is connected with an inverting input end of the column line driving operational amplifier through the other connecting line of the column multipath selector, and meanwhile, each other column line in the resistive sensor array is respectively connected with a reference voltage source through the two connecting lines of the resistive sensor array; meanwhile, a row line where the resistive sensor to be tested is located is connected with the inverted input end of the current feedback operational amplifier through one connecting line of the row multiplexer, and is connected with the other end of the test current setting resistor through the other connecting line of the row multiplexer, and meanwhile, each other row line in the resistive sensor array is respectively connected with a reference voltage source through the two connecting lines of the other row line; then, the resistance of the resistive sensor to be measured is calculated by using the following formula：
Wherein the content of the first and second substances,the feedback voltage of the output end of the operational amplifier is fed back by the current,a reference voltage provided for a reference voltage source,the potential of the resistor and the end of the row multiplexer to which it is connected is set for the test current,the resistance value of the resistor is set for the test current.
A sensing system comprising an array of resistive sensors sharing row and column lines and a corresponding sensing circuitM×NThe two-dimensional resistive sensor array is characterized in that the readout circuit is the resistive sensor array readout circuit based on the two-wire system equipotential method in any one of the technical schemes.
Compared with the prior art, the invention has the following beneficial effects:
1. aiming at the detection requirement of the resistive sensor array, on the basis of not improving the interconnection complexity of the array, a two-wire system voltage feedback method is taken as a key technology, so that the crosstalk error caused by the channel conduction resistance of a multi-channel selector, the contact resistance of a test cable joint and a long test cable is effectively eliminated, the measurement precision is improved, and meanwhile, the resistance range of a physical quantity sensitive resistor in the resistive sensor array is expanded; the invention can also effectively eliminate the interference of space electromagnetic noise;
2. the low-cost multiplexer with large channel on-resistance can be applied to the resistive sensor array, so that the cost of the test circuit is reduced;
3. the influence of the test cable joint contact, the resistance value of which changes along with time and the contact state, on the measurement precision of the resistive sensor array is eliminated, so that the resistive sensor array or a test circuit thereof can be replaced by the application system through a plug and a socket which are convenient to plug and unplug, and the measurement precision of the application system can be ensured.
4. The crosstalk error caused by the long test cable is eliminated, so that the long test cable can be applied to a resistive sensor array, and the flexible resistive sensor array is particularly suitable for the measurement of the flexible resistive sensor array with the requirement on the space size of a test circuit.
Drawings
FIG. 1 is a schematic view of a common row and column lineMThe structure schematic diagram of the x N two-dimensional resistive sensor array;
FIG. 2 is a schematic diagram of an equipotential readout circuit of a conventional shared row-column resistive sensor array;
FIG. 3 is a readout principle equivalent diagram of the readout circuit of FIG. 2;
FIG. 4 is a schematic diagram of one embodiment of a sensing circuit of the present invention;
FIG. 5 is a readout principle equivalent of the readout circuit of FIG. 4;
FIG. 6 is a schematic diagram of another embodiment of a sensing circuit of the present invention;
fig. 7 is a readout principle equivalent diagram of the readout circuit of fig. 6.
Detailed Description
The technical scheme of the invention is explained in detail in the following with the accompanying drawings:
FIG. 2 shows the principle of the equipotential readout circuit of the prior shared row-column line resistive sensor array, in which the current resistive sensor to be tested isR xy Is composed ofM×NIn arrays of shared row-column line resistive sensorsR 11 Fig. 3 is a readout principle equivalent diagram of the readout circuit of fig. 2. In this sensing circuit there is only one connection line between each row or column line of the array and the test circuit. In ideal working state, the circuit has channel on-resistance of one-out-of-two multi-way switch for all column linesR sc Cumulative resistance of lead resistance and joint contact resistance of drive connecting wireR Lc Is ignored, thusR xy Voltage of column lineV cy =V xy The voltage of the other column line is 0; simultaneous equal currentMChannel on-resistance of one-by-one multi-way switchR sr Cumulative resistance of lead resistance and joint contact resistance of equal current connecting wireR Lr Neglected, the voltage of the column line where the tested unit is located due to the action of the ideal current feedback operational amplifierV rx =0. Due to voltages of other column linesV rx Equal, so that of the unit under test: (N-1) the current on the row adjacent cell is 0; meanwhile, the reverse input end of the current feedback operational amplifier has large impedance, and the leakage current is ignored, so thatR xy Current ofI xy And testing the current setting resistanceR set Current ofI set Is equal toI set =-V I /R set =V xy /R xy . Due to the fact thatV I AndR set in the known manner, it is known that,R xy voltage ofV xy Can be measured and then calculatedR xy 。
Under the actual working condition of the reading circuit, the channel on-resistance of the two-way switch of the column line of the tested unitR sc Cumulative resistance of lead resistance and joint contact resistance of drive connecting wireR Lc Is present, resulting inV cy AndV xy not equal; at the same time, the current is equal in the row line direction of the tested unitMChannel on-resistance of one-by-one multi-way switchR sr Cumulative resistance of lead resistance and joint contact resistance of equal current connecting wireR Lr Is present, resulting inV rx Not equal to 0. The ideal isolation working condition of the circuit tested by the equal potential method is destroyed by the two main factors caused by the channel on-resistance of the row connecting cable, the column connecting cable and the multi-way switch, so that the ideal isolation working condition is ensuredR xy The measurement error becomes large.
In order to overcome the defects of the reading circuit shown in FIG. 2 and eliminate the influences of lead resistance of a connecting cable, contact resistance of a test cable joint, channel conduction resistance of a multi-way switch and the like, the invention provides a resistive sensor array reading circuit based on a two-wire system equipotential method, and the resistance value of each sensor in a shared row-line resistive sensor array is read by using the equipotential method of a double-connection wire.
The readout circuit of the present invention specifically includes: the circuit comprises a current feedback operational amplifier, a column line driving operational amplifier, a row multiplexer, a column multiplexer, a test current setting resistor, a reference voltage source and two connecting wires which are respectively arranged for each row line and column line of the resistive sensor array; the output end of the current feedback operational amplifier is connected with the non-inverting input end of the column line driving operational amplifier, the non-inverting input end of the current feedback operational amplifier is connected with a reference voltage source, and one end of the test current setting resistor is connected with a zero potential; the column multiplexer can enable any one column line in the resistive sensor array to be connected with the output end of the column line driving operational amplifier through one connecting line of the column line multiplexing selector, and to be connected with the inverting input end of the column line driving operational amplifier through the other connecting line of the column line multiplexing selector, and simultaneously enables each other column line in the resistive sensor array to be respectively connected with a reference voltage source through the two connecting lines of the resistive sensor array; the line multiplexer can enable any one of the line lines in the resistive sensor array to be connected with the inverting input end of the current feedback operational amplifier through one connecting line of the line selector, and to be connected with the other end of the test current setting resistor through the other connecting line of the line selector, and meanwhile, each of the other line lines in the resistive sensor array is respectively connected with the reference voltage source through the two connecting lines of the line selector.
In the readout method of the readout circuit, for any resistive sensor to be measured in the resistive sensor array, the resistive sensor to be measured is firstly gated, specifically as follows: the column line where the resistive sensor to be tested is located is connected with the output end of the column line driving operational amplifier through one connecting line of the column line multi-path selector, and is connected with the inverting input end of the column line driving operational amplifier through the other connecting line of the column line multi-path selector, and meanwhile, each other column line in the resistive sensor array is respectively connected with a zero potential through the two connecting lines of the resistive sensor array; meanwhile, a row line where the resistive sensor to be tested is located is connected with the inverted input end of the current feedback operational amplifier through one connecting line of the row multiplexer, and is connected with the other end of the test current setting resistor through the other connecting line of the row multiplexer, and meanwhile, each other row line in the resistive sensor array is respectively connected with zero potential through the two connecting lines of the other row line; then, the resistance of the resistive sensor to be measured is calculated by using the following formula：
Wherein the content of the first and second substances,the feedback voltage of the output end of the operational amplifier is fed back by the current,a reference voltage provided for a reference voltage source,the potential of the resistor and the end of the row multiplexer to which it is connected is set for the test current,the resistance value of the resistor is set for the test current.
The reading circuit of the invention can also adopt another structure, namely the zero potential position and the reference voltage source position in the technical scheme are exchanged, which is concretely as follows:
resistive sensor array read-out circuit based on two-wire system equipotential method, wherein the resistive sensor array shares row wires and column wiresM×NA two-dimensional resistive sensor array; wherein the readout circuit comprises: the circuit comprises a current feedback operational amplifier, a column line driving operational amplifier, a row multiplexer, a column multiplexer, a test current setting resistor, a reference voltage source and two connecting wires which are respectively arranged for each row line and column line of the resistive sensor array; the output end of the current feedback operational amplifier is connected with the non-inverting input end of the column line driving operational amplifier, the non-inverting input end of the current feedback operational amplifier is connected with a reference voltage source, and one end of the test current setting resistor is connected with a zero potential; the column multiplexer can enable any one column line in the resistive sensor array to be connected with the output end of the column line driving operational amplifier through one connecting line of the column line multiplexing selector, and to be connected with the inverting input end of the column line driving operational amplifier through the other connecting line of the column line multiplexing selector, and simultaneously enables each other column line in the resistive sensor array to be respectively connected with a reference voltage source through the two connecting lines of the resistive sensor array; the row multiplexer can enable any one row line in the resistive sensor array to be connected with the inverted input end of the current feedback operational amplifier through one connecting line of the row line, and the inverted input end of the current feedback operational amplifier is connected with the inverted input end of the current feedback operational amplifier through the one connecting lineAnd the other connecting wire is connected with the other end of the test current setting resistor, and simultaneously, each other row line in the resistive sensor array is respectively connected with a reference voltage source through the two connecting wires.
As for any resistive sensor to be tested in the resistive sensor array, the method for reading out the circuit gates the resistive sensor to be tested first, specifically as follows: the method comprises the following steps that a column line where a resistive sensor to be detected is located is connected with an output end of a column line driving operational amplifier through one connecting line of the column line multipath selector, and is connected with an inverting input end of the column line driving operational amplifier through the other connecting line of the column multipath selector, and meanwhile, each other column line in the resistive sensor array is respectively connected with a reference voltage source through the two connecting lines of the resistive sensor array; meanwhile, a row line where the resistive sensor to be tested is located is connected with the inverted input end of the current feedback operational amplifier through one connecting line of the row multiplexer, and is connected with the other end of the test current setting resistor through the other connecting line of the row multiplexer, and meanwhile, each other row line in the resistive sensor array is respectively connected with a reference voltage source through the two connecting lines of the other row line; then, the resistance of the resistive sensor to be measured is calculated by using the following formula：
Wherein the content of the first and second substances,the feedback voltage of the output end of the operational amplifier is fed back by the current,a reference voltage provided for a reference voltage source,the potential of the resistor and the end of the row multiplexer to which it is connected is set for the test current,the resistance value of the resistor is set for the test current.
In order to facilitate understanding of the public, the technical solution of the present invention is described in detail in the following with two specific embodiments.
FIG. 4 shows the circuit principle of an embodiment of the readout circuit of the present invention, in which the resistive sensor under test is currently testedR xy Is composed ofM×NIn arrays of shared row-column line resistive sensorsR 11 Fig. 5 is an equivalent diagram of the test principle of the readout circuit of fig. 4. In the present embodiment are respectivelyMA double-pole double-throw switch andNthe double-pole double-throw switches are used for respectively constructing a row multiplexer and a column multiplexer. As shown in FIG. 4, the invention isM×NEach row line or column line of the shared row-column line resistive sensor array is additionally provided with a connecting line, namely each column line and each column line correspond to two connecting lines (for convenience of distinction, from the functional point of view, the two connecting lines of the same row line are respectively called a driving connecting line and a driving sampling following connecting line, and the two connecting lines of the same column line are respectively called an equal current connecting line and an equal potential connecting line). Each column line of the shared row-column line resistive sensor array is respectively connected with two public ends of a column double-pole double-throw switch through a driving connecting line and a driving sampling following connecting line of the row-column line resistive sensor array, each column double-pole double-throw switch synchronously acts, namely the column double-pole double-throw switch is simultaneously attracted or released,Nroot row line common connectionNA pair of independent ends of each column double-pole double-throw switch are respectively connected to the output end and the inverted input end of a column line driving operational amplifier, and the other pair of independent ends are connected to a zero potential; the non-inverting input end of the column line driving operational amplifier is connected with the feedback voltage output by the output end of the current feedback operational amplifierV xy . Each row line of the shared row-line resistive sensor array is respectively connected with two public ends of a row double-pole double-throw switch through an equal current connecting line and an equal potential connecting line of the row-line resistive sensor array, each row double-pole double-throw switch synchronously acts, namely the row double-pole double-throw switch is simultaneously attracted or released,Mroot row line common connectionMA pair of independent ends of each row double-pole double-throw switch are respectively connected to the reverse phase input end of the current feedback operational amplifier and the test current settingResistance (RC)R set The other pair of independent ends are connected with zero potential; test current setting resistanceR set The other end of the reference voltage source is connected with the reference voltage provided by the reference voltage sourceV I The non-inverting input end of the current feedback operational amplifier is connected with zero potential.
During testing, the row double-pole double-throw switch where the current row unit to be tested is located is closed, and the other rows of double-pole double-throw switches are disconnected; and the row double-pole double-throw switch where the current row unit to be tested is located is closed, and the other row double-pole double-throw switches are disconnected. Therefore, other column lines in the sensor array are grounded, and only the column line where the current to-be-detected column unit is located is connected with the output end and the inverting input end of the column line driving operational amplifier; meanwhile, other row lines in the sensor array are grounded, and only the row line where the current row unit to be tested is located and the test current set resistorR set And the inverting input end of the current feedback operational amplifier is connected. Therefore, the voltage of the column line of the current unit to be tested is under the action of virtual short and virtual disconnection of the column line driving operational amplifierV cy In-phase input terminal voltage following row line driven operational amplifierV xy But may vary. The input impedance of the inverting input end of the column line driving operational amplifier and the resistance value of the switch contact resistor of the column double-pole double-throw switchR sc And the lead resistances of the driving connection line and the column driving sampling following connection line and the cumulative resistance of the contact resistances thereofR Lc The comparison is very large, and due to the virtual short and virtual disconnection of the column line driving operational amplifier, the column line voltage of the current unit to be tested isV cy In-phase input terminal voltage following row line driven operational amplifierV xy Equality, cancelable read circuitR Lc 、R sc To pairR xy The effect of the measurement results. The voltage of the row line where the current unit to be tested is positioned is under the virtual short action of the current feedback operational amplifierV rx The current feedback operational amplifier keeps the same potential virtual ground with the same-phase input end of the current feedback operational amplifier, but the current scanning row line and the current scanning column line are grounded through the double-pole double-throw switch thereof and are virtually isolated; due to current feedbackVirtual short, virtual cut-off action of the amplifier, current on the unit to be measuredI xy Setting resistor following test currentR set Current ofI set But may vary. The input impedance of the inverting input end of the current feedback operational amplifier and the resistance value of the switch contact resistance of the row double-pole double-throw switchR sr And the lead resistance of the equal current connection line and the equal potential connection line and the cumulative resistance of the contact resistance of the sameR Lr The comparison is very large, and the current on the current to-be-detected column unit is caused by the virtual breaking action of the column line driving operational amplifierI xy Setting resistor following test currentR set Current ofI set Equality, cancelable read circuitR Lr 、R sr To pairR xy The effect of the measurement results.
FromV I First, a test current is passedR set Then, the current passes through the row double-pole double-throw switch, then passes through the equal-current connecting wire again to the row line of the tested unit, and then passes through the tested unit to the column line of the tested unit. The input impedance of the inverting input end of the current feedback operational amplifier is very large and is far larger than the switch contact resistance of the row double-pole double-throw switchR sr Lead resistance and contact resistance of equipotential connecting lineR Lr The sum of the two-phase current feedback operational amplifier can be considered as that the voltage of the inverting input end of the current feedback operational amplifier is equal to the voltage of the line voltage of the tested unit, and the value of the sum is 0; the input impedance of the inverting input end of the current feedback operational amplifier is large and far greater than that of the inverting input end of the current feedback operational amplifierR set Switch contact resistance of double-pole double-throw switchR sr Lead resistor of constant current connecting wire and contact resistor thereofR Lr Cumulative resistance ofR er Therefore, the leakage current of the inverting input end of the current feedback operational amplifier can be ignored; while the other column lines and the tested row line keep equal zero potential, the leakage current on the adjacent unit of the tested unit row is zero. Thus, it is possible to provideR set AndR xy the passing currents of the two circuits are equal, and the currents are also the sameCumulative resistance caused by common use of switch contact resistance of row double-pole double-throw switch, lead resistance of equal current connecting wire, contact resistance of equal current connecting wire and the likeR er While the current value is unchanged. Due to the fact thatR set AndR xy the currents on are equal becauseR set Is known, then if it is knownR set The precise voltage across can be determinedI xy . WhileV xy Can be measured and thus calculated accuratelyR xy 。
But due to accumulated resistanceR er Is caused to pass throughR set Current ofI real =-V I /(R set +R er )=V xy /R xy And the ideal set currentI set =-V I /R set Difference, cumulative resistanceR er Resulting in an error voltage ofV e Therefore if neglectedR er Will cause additional errors in the test results of the unit under test. Due to the fact thatR xy 、R set AndR er the currents flowing in the upper part are equal, so that the current can be adoptedR xy =V xy ×R set /(V e -V I ) To obtainR xy The resistance value of (c). It can be found that there is no in this formulaR er The presence of the one or more of,R er the effect of (c) is completely eliminated. Due to the fact thatR set AndV I is known, andV e andV xy we can measure and get, finally realizeR xy And (4) measuring a true value.
FIG. 6 shows another embodiment of the sensing circuit of the present invention, showing a current cell under testR xy Is composed ofM×NIn arrays of shared row-column line resistive sensorsR 11 (ii) a Fig. 7 is a readout principle equivalent diagram of the readout circuit of fig. 6. As shown in fig. 6, the readout circuit of the present embodiment is equivalent to exchanging the reference voltage source and the zero potential access position in the readout circuit of fig. 4, that is, the original zero potential position in the readout circuit of fig. 4 is changed to the reference voltage source, and the original reference voltage source position is changed to the zero potential. The test method of the test circuit comprises the following specific steps:
for any resistive sensor to be tested in the resistive sensor array, the resistive sensor to be tested is gated first, specifically as follows: the method comprises the following steps that a column line where a resistive sensor to be detected is located is connected with an output end of a column line driving operational amplifier through one connecting line of the column line multipath selector, and is connected with an inverting input end of the column line driving operational amplifier through the other connecting line of the column multipath selector, and meanwhile, each other column line in the resistive sensor array is respectively connected with a reference voltage source through the two connecting lines of the resistive sensor array; meanwhile, a row line where the resistive sensor to be tested is located is connected with the inverted input end of the current feedback operational amplifier through one connecting line of the row multiplexer, and is connected with the other end of the test current setting resistor through the other connecting line of the row multiplexer, and meanwhile, each other row line in the resistive sensor array is respectively connected with a reference voltage source through the two connecting lines of the other row line; then, the resistance of the resistive sensor to be measured is calculated by using the following formula：
Wherein the content of the first and second substances,the feedback voltage of the output end of the operational amplifier is fed back by the current,a reference voltage provided for a reference voltage source,the potential of the resistor and the end of the row multiplexer to which it is connected is set for the test current,the resistance value of the resistor is set for the test current.
The basic principle of the sensing circuit of fig. 6 for eliminating crosstalk errors caused by the channel on-resistance of the multiplexer, the contact resistance of the test connector, and the long test cable is the same as that of fig. 4, and is clearly understood by those skilled in the art from the above description and fig. 6 and 7; for the sake of brevity, no further description is provided herein. Compared with the readout circuit of fig. 4, with the readout circuit of fig. 6, all operational amplifiers can adopt rail-to-rail unipolar operational amplifiers, and only a unipolar reference voltage source needs to be provided at this time, so that the power supply cost is reduced.
In summary, with the readout circuit of the present invention, the real resistance of any unit to be tested in the resistive sensor array sharing the row line can be accurately measured, and the influence caused by the lead resistances of the row line and the row line of the resistive sensor array, the contact resistances of the joints thereof, and the on-resistance of the multi-way switch channel is completely eliminated.
Furthermore, it is to be emphasized that: the above-mentioned row and column concepts can be completely interchanged by those skilled in the art, and the row multiplexer and the column multiplexer can also be implemented by other specific structures; therefore, similar simple modifications based on the idea of the present invention are still covered by the technical solution of the present invention.

Claims (9)

1. Resistive sensor array read-out circuit based on two-wire system equipotential method, wherein the resistive sensor array shares row wires and column wiresM×NA two-dimensional resistive sensor array; wherein the readout circuit comprises: a current feedback op-amp, a column line driver op-amp, row multiplexer, column multiplexer, test current setting resistor, reference voltage source, and a reference voltage source for each of the row and column lines of the resistive sensor arrayTwo connecting wires are respectively arranged; the output end of the current feedback operational amplifier is connected with the non-inverting input end of the column line driving operational amplifier, the non-inverting input end of the current feedback operational amplifier is connected with a zero potential, and one end of the test current setting resistor is connected with a reference voltage source; the column multiplexer can enable any one column line in the resistive sensor array to be connected with the output end of the column line driving operational amplifier through one connecting line of the column line multiplexing selector, and to be connected with the inverting input end of the column line driving operational amplifier through the other connecting line of the column line multiplexing selector, and simultaneously enables each other column line in the resistive sensor array to be respectively connected with a zero potential through the two connecting lines of the resistive sensor array; the line multiplexer can enable any one line in the resistive sensor array to be connected with the inverted input end of the current feedback operational amplifier through one connecting line, and connected with the other end of the test current setting resistor through the other connecting line, and meanwhile, each other line in the resistive sensor array is respectively connected with zero potential through the two connecting lines.
2. A sensing circuit of claim 1, wherein the row multiplexer comprises a resistive sensor arrayMWith one-to-one correspondence of strips and linesMA row double pole double throw switch; for each row double-pole double-throw switch, one pair of common ends of the row double-pole double-throw switch is respectively connected with the row line through two connecting lines of the corresponding row line, one pair of independent ends of the row double-pole double-throw switch is respectively connected with the inverted input end of the current feedback operational amplifier and the other end of the test current setting resistor, and the other pair of independent ends of the row double-pole double-throw switch is connected with zero potential.
3. The sensing circuit of claim 1, wherein the column multiplexer comprises a resistive sensor arrayNWith one-to-one correspondence of row and column linesNA row of double pole double throw switches; for each column double-pole double-throw switch, a pair of common ends of the column double-pole double-throw switch are respectively connected with the column line through two connecting wires of the corresponding column line, one pair of independent ends of the column double-pole double-throw switch are respectively connected with the output end of the column line driving operational amplifier and the inverted input end of the column line driving operational amplifier, and the other pair of independent ends of the column double-pole double-throw switch is connected with the output end of the column line driving operational amplifier and theA pair of independent terminals are connected with zero potential.
4. A method for sensing a resistive sensor of a sensing circuit according to any one of claims 1 to 3, wherein for any resistive sensor to be sensed in the array of resistive sensors, the resistive sensor to be sensed is first gated, specifically as follows: the column line where the resistive sensor to be tested is located is connected with the output end of the column line driving operational amplifier through one connecting line of the column line multi-path selector, and is connected with the inverting input end of the column line driving operational amplifier through the other connecting line of the column line multi-path selector, and meanwhile, each other column line in the resistive sensor array is respectively connected with a zero potential through the two connecting lines of the resistive sensor array; meanwhile, a row line where the resistive sensor to be tested is located is connected with the inverted input end of the current feedback operational amplifier through one connecting line of the row multiplexer, and is connected with the other end of the test current setting resistor through the other connecting line of the row multiplexer, and meanwhile, each other row line in the resistive sensor array is respectively connected with zero potential through the two connecting lines of the other row line; then, the resistance of the resistive sensor to be measured is calculated by using the following formula：
Wherein the content of the first and second substances,the feedback voltage of the output end of the operational amplifier is fed back by the current,a reference voltage provided for a reference voltage source,the potential of the resistor and the end of the row multiplexer to which it is connected is set for the test current,the resistance value of the resistor is set for the test current.
5. Resistive sensor array read-out circuit based on two-wire system equipotential method, wherein the resistive sensor array shares row wires and column wiresM×NA two-dimensional resistive sensor array; wherein the readout circuit comprises: the circuit comprises a current feedback operational amplifier, a column line driving operational amplifier, a row multiplexer, a column multiplexer, a test current setting resistor, a reference voltage source and two connecting wires which are respectively arranged for each row line and column line of the resistive sensor array; the output end of the current feedback operational amplifier is connected with the non-inverting input end of the column line driving operational amplifier, the non-inverting input end of the current feedback operational amplifier is connected with a reference voltage source, and one end of the test current setting resistor is connected with a zero potential; the column multiplexer can enable any one column line in the resistive sensor array to be connected with the output end of the column line driving operational amplifier through one connecting line of the column line multiplexing selector, and to be connected with the inverting input end of the column line driving operational amplifier through the other connecting line of the column line multiplexing selector, and simultaneously enables each other column line in the resistive sensor array to be respectively connected with a reference voltage source through the two connecting lines of the resistive sensor array; the line multiplexer can enable any one of the line lines in the resistive sensor array to be connected with the inverting input end of the current feedback operational amplifier through one connecting line of the line selector, and to be connected with the other end of the test current setting resistor through the other connecting line of the line selector, and meanwhile, each of the other line lines in the resistive sensor array is respectively connected with the reference voltage source through the two connecting lines of the line selector.
6. A sensing circuit of claim 5, wherein the row multiplexer comprises a resistive sensor arrayMWith one-to-one correspondence of strips and linesMA row double pole double throw switch; for each row double-pole double-throw switch, a pair of public ends of the row double-pole double-throw switch are respectively connected with the corresponding row line through two connecting wires of the row line, and one pair of independent ends of the row double-pole double-throw switch is respectively connected with the inverted input end of the current feedback operational amplifier and the other end of the test current setting resistorAnd the other pair of independent terminals of the row of double-pole double-throw switches are connected with a reference voltage source.
7. A sensing circuit of claim 5, wherein the column multiplexer comprises a resistive sensor arrayNWith one-to-one correspondence of row and column linesNA row of double pole double throw switches; for each column double-pole double-throw switch, a pair of common ends of the column double-pole double-throw switch are respectively connected with the column line through two connecting wires of the corresponding column line, one pair of independent ends of the column double-pole double-throw switch are respectively connected with the output end of the column line driving operational amplifier and the inverted input end of the column line driving operational amplifier, and the other pair of independent ends of the column double-pole double-throw switch are both connected with a reference voltage source.
8. A method of sensing in a sensing circuit of claim 5, wherein for any resistive sensor under test in the array of resistive sensors, the resistive sensor under test is first gated as follows: the method comprises the following steps that a column line where a resistive sensor to be detected is located is connected with an output end of a column line driving operational amplifier through one connecting line of the column line multipath selector, and is connected with an inverting input end of the column line driving operational amplifier through the other connecting line of the column multipath selector, and meanwhile, each other column line in the resistive sensor array is respectively connected with a reference voltage source through the two connecting lines of the resistive sensor array; meanwhile, a row line where the resistive sensor to be tested is located is connected with the inverted input end of the current feedback operational amplifier through one connecting line of the row multiplexer, and is connected with the other end of the test current setting resistor through the other connecting line of the row multiplexer, and meanwhile, each other row line in the resistive sensor array is respectively connected with a reference voltage source through the two connecting lines of the other row line; then, the resistance of the resistive sensor to be measured is calculated by using the following formula：
Wherein the content of the first and second substances,the feedback voltage of the output end of the operational amplifier is fed back by the current,a reference voltage provided for a reference voltage source,the potential of the resistor and the end of the row multiplexer to which it is connected is set for the test current,the resistance value of the resistor is set for the test current.
9. A sensing system comprising an array of resistive sensors sharing row and column lines and a corresponding sensing circuitMA xN two-dimensional resistive sensor array, wherein the readout circuit is a resistive sensor array readout circuit based on a two-wire system equipotential method according to any one of claims 1 to 3 and 5 to 7.
CN201810635406.5A 2018-06-20 2018-06-20 Resistive sensor array reading circuit based on two-wire system equipotential method Withdrawn CN110617841A (en)

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