KR20090011396A - Calibration method for current-driven sensor and the apparatus thereof - Google Patents

Abstract

An error correction device of a sensor measurement circuit and a method thereof are provided to verify accuracy of a sensor in a real-time period and to correct an error in an abnormal state in a real-time period. A sensor(120) and two or more resistors(130,140) are connected in parallel to a constant current source(110). A first switch unit(150) is installed in a parallel line. A second switch unit(160) is installed in an output line of the sensor and output lines of the resistors. The second switch unit is connected to an input side of an amplifier(170). An output side of the amplifier is connected to an input side of an analog/digital converter(180). An output side of the analog/digital converter is connected to a correction unit(190). The correction unit corrects the output value of the sensor by linearizing output values of the resistors.

Description

Calibration method for current-driven sensor and the apparatus thereof}

The present invention relates to an error correction device and an error correction method of a sensor measuring device.

In general, the measured value using the sensor has an error, and based on the component in which the error occurs, the error of the sensor itself caused by the design and the process of the sensor is large, the sensor is driven, and the value output from the sensor is processed. It can be divided into errors caused by devices or components (measuring devices) except for the sensors necessary to do so. In addition, it can be divided into errors due to deterioration associated with long-term use, errors due to temperature / pressure, and simple system errors caused by digital circuits among components.

Among these errors, the biggest influence on the sensor's final measurement results is the effects of degradation, temperature and pressure on the measuring equipment using analog devices.

Regular calibration of measuring equipment is essential to get accurate measurement results. As a general method, regular check-ups of the measuring equipment are carried out at regular time intervals to determine the abnormality of the measuring equipment and to perform calibration.

After the actual product is released, it is necessary to correct the error of the sensor and the sensor measurement circuit that can be made immediately and in real time as the use environment such as process variables in manufacturing and assembly, deterioration due to use, and temperature changes, Phosphorus examination has a limitation in that it is not possible to know in real time whether there is an abnormality in the measured value using the measuring equipment.

An object of the present invention for solving the above problems is to correct the error caused by the temperature or deterioration of the sensor device itself without the introduction of an external device, the error correction of the sensor measurement circuit for correcting the error by judging itself whether there is an abnormality An apparatus and method are provided.

In the error correction device of the sensor measurement circuit of the present invention, in the error correction device of the sensor 120 driven by the constant current source 110, the sensor 120 and two or more resistors (130, 140) is the constant current source ( 110 connected in parallel, the parallel line is provided with a first switch unit 150, the output line of the sensor 120 and the second switch unit on the output line of the two or more resistors (130, 140) 160 is provided and the second switch unit 160 is connected to the input side of the amplifier 170, the output side of the amplifier 170 is connected to the input side of the analog / digital converter 180 and the analog / digital The output side of the transducer 180 is connected to the corrector 190, and the sensor 120 is linearized by receiving and outputting the output values of the two or more resistors 130 and 140 from the corrector 190. ), The output value is corrected.

Correction of the output value by the sensor 120 is the first correction and the sensor 120 itself to correct the error by the configuration device including the constant current source, the amplifier and the analog / digital converter by the linearized equation The linearization is corrected by a second correction that corrects the error of the linearization between the two or more resistance values and the output value by the two or more resistors or the value of the voltage determined by the value of the two or more resistors and the two values. This is linearization of the output value by the above resistance.

The correction unit 190 preferably includes a correction program, a computer readable medium storing data on the values of the two or more resistances and the error of the sensor itself, and a processor accessing the medium and executing the correction program. Do.

In the error correction method of the sensor measurement circuit of the present invention, in the error correction method of the sensor 120 driven by the constant current source 110, an output value of two or more resistors connected in parallel with the sensor with respect to the constant current source. Obtaining (s120 and s130) for each of said resistors; Linearizing the values of the two or more resistors and the two or more output values to obtain a linearized equation (s140); Obtaining an output value by the sensor (s150); A first correction step (s160) of correcting the output value by the sensor using the linearized equation; and a second correction step (170) of correcting the output value by the sensor using data on the error of the sensor itself; It has features to include.

The linearization is a linearization of the value of the voltage determined by the value of the two or more resistors and the output value of the two or more resistors.

The present invention can correct the error caused by the temperature and deterioration of the sensor measuring device, which is a component except the sensor, by linearization using the output values of two or more resistors without introducing external equipment, and verify the accuracy of the sensor in real time. It can be corrected in real time in case of abnormalities.

In the error compensator of the present invention, in the sensor 120 driven by the constant current source 110, the sensor 120 and two or more resistors 130 and 140 are connected in parallel with the constant current source 110. The first switch unit 150 is provided on the parallel line, and the second switch unit 160 is provided on the output line of the sensor 120 and the output line of the two or more resistors 130 and 140. The switch unit 160 is connected to the input side of the amplifier 170, the output side of the amplifier 170 is connected to the input side of the analog-to-digital converter 180, the output side of the analog-to-digital converter 180 is the correction unit 190 ), The correction unit 190 receives and linearizes the output values of the two or more resistors 130 and 140, thereby correcting the output value of the sensor 120 by the linearized equation.

Sensors to which the error correction apparatus and method of the present invention can be applied are all driven by a constant current source and outputting an electrical signal (voltage, resistance, current), but are preferably a pressure sensor or a temperature sensor. The pressure sensor is more preferably a bridge type pressure sensor including a semiconductor pressure sensor and a piezoelectric sensor, and the temperature sensor is more preferably a temperature sensor by a 4-wire resistance measurement method including a thermistor and a platinum resistance sensor.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided as examples to sufficiently convey the spirit of the present invention to those skilled in the art. Accordingly, the invention is not limited to the embodiments described below and may be embodied in other forms. Also, like reference numerals denote like elements throughout the specification.

In addition, unless there is another definition in the technical terms and scientific terms used, it has the meaning that is commonly understood by those of ordinary skill in the art.

1 is an example showing the configuration of an error compensating device of a sensor measuring circuit of the present invention. In FIG. 1, only two resistors 130 and 140 are used for correction, but the present invention is not limited thereto.

As can be seen in Figure 1 the error correction device of the present invention is a constant current source, a sensor 120 driven by a constant current source 110 and two resistors (130, 140) for the constant current source 110, the sensor ( A first switch unit 150 connected in parallel with 120 and having switches 151, 152, and 153 in each of the parallel lines is present, and an output line of the sensor 120 and the two resistors 130. And a second switch unit 160 including switches 161, 162, and 163 on the output lines of the second and second lines 140, and the second switch unit 160 is connected to an input side of the amplifier 170. The output side of the 170 is connected to the input side of the analog-to-digital converter 180 and the output side of the analog-to-digital converter 180 has a configuration connected to the correction unit 190.

The correction unit 190 is a computer-readable medium 191 storing a correction program, values of the two resistances, data on the error of the sensor itself, and error data by designing, manufacturing and assembling a measuring device including the sensor. And a processor 192 that accesses the medium and executes the calibration program. The calibration program reads the values of two resistors 130 and 140 connected in parallel with the sensor 120 with respect to the constant current source 110 from the medium and uses them as a standard that does not change in the linearization operation for error correction. Done. In this case, a specific voltage value by the resistor may be read from the medium instead of the values of the resistors 130 and 140.

In addition, the correction unit 190 controls the first switch unit 150 and the second switch unit 160, in this case, the control may be performed by the processor 192, as shown in FIG. As described above, the correction unit 190 may be further configured to include the controller 193 to control the first switch unit 150 and the second switch unit 160 by the controller 193.

The first and second switch units 150 and 160 select one component of the sensor and two resistors 130 and 140 to generate an output. The first switch unit 150 is composed of switches 151, 152, and 153 provided on the parallel lines, respectively, and the second switch unit 160 includes switches provided on the output lines. Each of the switches 151, 162, 163, and 163, and the switches 151, 152, 153, 161, 162, 163 constituting the first switch unit 150 and the second switch unit 160 are respectively controlled by the corrector 190. Accordingly, the first and second switch units 150 and 160 determine the measurement line.

Correction of the output value by the sensor 120 is the first correction to correct the error by the component (sensor measurement circuit) including the constant current source, the amplifier and the analog-to-digital converter by the linearized equation and the The sensor 120 is made of a second correction to correct an error of itself.

In the first correction, the linearized equation corrects an error due to temperature or deterioration caused by a sensor measuring circuit that is a component (constant current source, amplifier, analog / digital converter) other than the sensor 120. In the difference correction, the error of the sensor 120 itself is corrected. Therefore, the correction of the present invention is to correct the error by all the components up to the sensor 120 and the front end of the digital processor except the sensor (up to the front end of the correction).

The linearization may be a linearization between the two resistance values and the output values of the two resistors or a linearization of the voltage value determined by the values of the two resistors and the output values of the two resistors.

The two resistance values serve as reference points for error correction, and the output values obtained by the two resistors are obtained with respect to the previously inputted resistance values, and the linearization is performed using the resistance as one axis (or variable) and the output value as one axis (or variable). To calibrate the output to the sensor using a linearized equation. Alternatively, the predetermined voltage value determined by the two resistance values rather than the resistance value and the output value may be linearized by using one axis (or variable) and the output value as one axis (or variable). At this time, the output value is obtained as a digital value by the analog-to-digital converter 180.

The secondary correction may be correction by error data of the sensor 120 itself as described above, and may be applied to error data by designing, manufacturing, and assembling a measuring device including a sensor stored in a computer-readable medium 191. May be a secondary correction.

FIG. 2 is a graph showing first order correction by a linearized equation based on the configuration of FIG. 1. The straight line (a) of FIG. 2 is a linear equation in which errors due to the design of all components from the reference temperature to the front end of the digital processor including the sensor 120 (up to the front end of the compensator) are corrected. At this time, a new error occurs due to a change in temperature or deterioration. To correct this, as described above, in the configuration of FIG. 1, an output value A of one of the two resistors (hereinafter referred to as R1) is obtained, and the other of the two resistors (hereinafter referred to as R2) is obtained. After obtaining the output value (B), a new straight line (b) can be obtained through the linearization operation. Therefore, when the resistance of the sensor at the time of obtaining the output value of S, the output value (C) of the linearized linear sensor can have the value of the output value (D) in which the error due to temperature change or deterioration is corrected. .

This allows correction of errors for all components up to the front end of the digital processor except the sensor (up to the front end of the compensation), and from the computer readable medium 191 storing data about the error of the sensor itself to the error of the sensor itself. The error caused by the sensor is also corrected by the second correction, which reads and corrects the information.

3 is a partial circuit diagram of an embodiment of a circuit diagram implementing the error compensating apparatus of the present invention, wherein the partial circuit diagram is a part provided with a constant current source 110 and the resistors 130 and 140.

In the circuit diagram of FIG. 3, two resistors connected in parallel with a sensor with respect to the constant current source are connected in series with each other, and measured by each of the two resistors connected in series with each other through a series connection rather than a parallel connection between the two resistors. The advantage is that you get the values at the same time. As can be seen in Figure 3 is characterized in that the output value of the two resistors that already know the resistance value as a reference for the correction, the two resistors are characterized in that connected in parallel with the sensor with respect to the constant current source, The two resistors may be connected in series with each other as shown in FIG. 3, and may be connected in parallel with each other as shown in FIG. 1.

In the error correction method of the sensor 120 driven by the constant current source 110 of the present invention, the output value of two or more resistors connected in parallel with the sensor with respect to the constant current source is obtained for each of the resistors (s120). And s130); Linearizing the values of the two or more resistors and the two or more output values to obtain a linearized equation (s140); Obtaining an output value by the sensor (s150); A first correction step (s160) of correcting the output value of the sensor by using the linearized equation; and a second correction step (170) of correcting the output value of the sensor by using data on the error of the sensor itself; It has features to include.

The error correction method is performed by the correction unit 190 of the error correction apparatus of the sensor measurement circuit of the present invention.

4 is an example of a flowchart of an error correction method of a sensor measuring circuit of the present invention based on the configuration of FIG. 1.

In the step of determining whether the error is corrected (S110), the error correction may be performed when power is applied to a device equipped with a sensor to measure by using a sensor, and a state in which power is applied to the sensor is used. May be performed at regular intervals. When error correction is performed, an output value obtained by R1 is obtained (s120), an output value obtained by R2 is obtained (s130), and a linearization formula is obtained by linearizing the resistance value of R1 and the resistance value of R2 and the two output values (s140). . After the linearization operation is performed, a first correction is performed based on the linearization equation by obtaining an output value s150 by the sensor (s160), and a second correction (s170) is performed to correct an error of the sensor itself. In this case, if the error is not corrected, step S150 is performed. When continuously measuring the output value using the sensor, step S150 may be repeatedly performed.

In this case, the linearization may be a linearization of the voltage value determined by the resistance values of the R1 and R2 and the output values of the two resistors.

In the embodiment of FIG. 1 excluding the sensor by the first correction step (s160), errors for all components up to the digital processor front end (up to the front end of the correction unit) are corrected, and the second correction step The error of the sensor itself is corrected by (s170). Data about the resistance values of the R1 and R2 and the error of the sensor itself is read in the information from the stored computer readable medium 191 in the linearization step, the first correction step and the second correction step (s140, s160, s170). Will be used.

Although the linearization operation is performed before obtaining the output value by the sensor in the flowchart of FIG. 4, the linearization step may be performed after obtaining the output values by R1, R2 and the sensor, and after the first correction, the second correction may be performed. Although the first correction may be performed after the second correction.

In order to increase the reliability of the correction, the output value of R1 and the output value of R2 may be repeatedly measured, and the linearization step may be performed using the average of the output values.

In the error correction method of the present invention, as shown in FIG. 5, it is possible to correct an error in real time by determining whether or not the measurement value of the sensor is corrected by itself. As described above with reference to FIG. 2, the straight line a of FIG. 5 is a linear type in which errors due to the design of all the components of the components from the reference temperature to the front end of the digital processor including the sensor 120 (up to the front end of the compensation) are corrected. The information on the straight line (a) is stored in a computer readable medium, and is accessed and loaded by a calibration program running using a processor. At this time, since the reference output values (E, F) for R1 and R2 having predetermined resistance values are known, the output values of R1 and / or R2 are periodically measured and compared with the reference output values (E, F) to compare the difference ( delR1, delR2) If it is above a certain value, by performing the calibration of FIG.

Figure 1 is an embodiment showing the configuration of the error correction device of the present invention,

2 is a graph showing the linearization correction of the present invention,

Figure 3 is a partial circuit diagram of an embodiment of a circuit diagram implementing the error correction device of the present invention,

4 is a flowchart of an error correction method of the present invention;

5 is another graph illustrating a correction method of the present invention.

Claims (6)

In the error correction device of the sensor 120 driven by the constant current source 110, The sensor 120 and two or more resistors 130 and 140 are connected in parallel with respect to the constant current source 110, The first switch unit 150 is provided on the parallel line, The second switch unit 160 is provided on the output line of the sensor 120 and the output lines of the two or more resistors 130 and 140, and the second switch unit 160 is connected to the input side of the amplifier 170. , The output side of the amplifier 170 is connected to the input side of the analog-to-digital converter 180 and the output side of the analog-to-digital converter 180 is connected to the correction unit 190, Error in the sensor measurement circuit, characterized in that the output value of the sensor 120 is corrected by the linearized equation by linearizing the output value of each of the two or more resistors (130, 140) in the corrector 190 Compensator. The method of claim 1, Correction of the output value by the sensor 120 is the first correction and the sensor 120 itself to correct the error by the configuration device including the constant current source, the amplifier and the analog / digital converter by the linearized equation Error correction device of the sensor measurement circuit, characterized in that the correction by the second correction to correct the error. The method of claim 1, The linearization is a linearization between the two or more resistance values and the output value by the two or more resistors or a linearization of the value of the voltage determined by the value of the two or more resistors and the output value by the two or more resistors. Error compensator of sensor measurement circuit. The method of claim 1, The correction unit 190 is configured to include a correction program, a computer readable medium storing data on the values of the two or more resistances and the sensor itself, and a processor accessing the medium and executing the correction program. Error compensator of sensor measurement circuit. In the error correction method of the sensor 120 driven by the constant current source 110, Obtaining (s120 and s130) output values for each of the resistors by two or more resistors connected in parallel with the sensor for the constant current source; Linearizing the values of the two or more resistors and the two or more output values to obtain a linearized equation (s140); Obtaining an output value by the sensor (s150); A first correction step (s160) of correcting the output value by the sensor using the linearized equation; and A second correction step 170 of correcting an output value by the sensor using data on the error of the sensor itself; Error correction method of the sensor measurement circuit comprising a. The method of claim 5, Wherein the linearization is a linearization of the voltage value determined by the values of the two or more resistors and the output value by the two or more resistors.

Images