JP2006170780A - Sensor output value detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensor output value detecting device capable of reducing a labor required for adjustments. <P>SOLUTION: The sensor output value detecting device 1 is equipped with a microcomputer 30. The microcomputer 30 is configured so as to read a reference voltage Va from a reference voltage generating circuit 20 disposed in addition to a sensor 10 in order to previously obtain a read error. Furthermore, the microcomputer 30 is configured so as to compensate an output voltage Vs of the sensor 10 based on the read error. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a sensor output value detection device.

Conventionally, when a sensor output is read (detected) by a microcomputer, a technique is known in which a variable resistor is provided and a resistance value of the variable resistor is adjusted in order to eliminate a reading gain error of the microcomputer (for example, Patent Document 1) reference).
JP-A-5-249128

  However, conventionally, it has been necessary to adjust the resistance value of the variable resistor for each sensor, which requires a great deal of time for adjustment.

  The present invention has been made to solve such a conventional problem, and an object of the present invention is to provide a sensor output value detection device capable of reducing the labor required for adjustment.

  The sensor output value detection device of the present invention includes a sensor that outputs a voltage value corresponding to a detection amount, and detection means that detects the detection amount based on the output voltage of the sensor. The sensor output value detection apparatus further includes a reference voltage generation unit, a calculation unit, and a correction unit. The reference voltage generating means outputs a reference voltage as a reference. The calculating means compares the reference voltage from the reference voltage generating means with the ideal value of the reference voltage stored in advance, and calculates the deviation ratio between them. The correcting means corrects the value of the voltage from the sensor in accordance with the deviation ratio calculated by the calculating means.

  According to the present invention, the detected amount of the reference voltage is compared with the ideal value of the detected amount of the reference voltage, and the ratio between the two is calculated. For this reason, an error in reading (detection) gain when the reference voltage is read by a microcomputer or the like can be clarified. Further, the detection amount of the output voltage of the sensor is corrected based on the obtained deviation rate. For this reason, the detection amount of the output voltage of the sensor is corrected based on the error of the read gain obtained based on the detection amount of the reference voltage. As described above, since the error of the reading (detection) gain of the microcomputer or the like is adjusted, there is no need to provide a variable resistor and adjust the resistance value of the variable resistor. Therefore, the labor required for adjustment can be reduced.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.

  FIG. 1 is a detailed configuration diagram of a sensor output value detection apparatus according to an embodiment of the present invention. As shown in the figure, the sensor output value detection device 1 has a function of eliminating a reading error when reading the output of the sensor, and includes a sensor 10, a reference voltage generation circuit (reference voltage generation means) 20, a microcomputer (detection). Means) 30.

  The sensor output value detection device 1 receives the output voltage Vs of the sensor 10 and receives the reference voltage Va from the reference voltage generation circuit 20 to obtain a reading error of the microcomputer 30 based on the reference voltage Va. Based on this error, the output voltage Vs of the sensor 10 is corrected. The sensor output value detection apparatus 1 outputs a signal (hereinafter referred to as a correction voltage) Vsr indicating a corrected voltage value to an external device or apparatus. Hereinafter, each element will be described in detail.

  The sensor 10 outputs, for example, a voltage value corresponding to the detection amount of a voltage sensor or a current sensor as an analog signal, and is directly connected to the A / D port of the microcomputer 30. Therefore, the output voltage Vs of the analog signal sensor 10 is directly input to the microcomputer 30 without going through an output value correction circuit or the like as in the prior art.

  The reference voltage generation circuit 20 outputs a reference voltage Va of an analog signal serving as a reference, and includes a Zener diode 21, a resistor 22, and a constant current circuit 23. The Zener diode 21 has an anode grounded and a cathode connected to the resistor 22. The resistor 22 has a constant current circuit 23 connected to the opposite side to which the Zener diode 21 is connected. The constant current circuit 23 causes a constant current to flow through the Zener diode 21 due to the connection relationship described above. The cathode of the Zener diode 21 is connected to the microcomputer 30. Then, the voltage on the cathode side of the Zener diode 21 is output to the microcomputer 30 as the reference voltage Va.

  The reference voltage generation circuit 20 is provided in the vicinity of the sensor 10 and is exposed to substantially the same temperature environment as the sensor 10. Here, the vicinity refers to a distance that allows the sensor 10 and the reference voltage generation circuit 20 to be exposed to substantially the same temperature environment.

  Further, the reference voltage generation circuit 20 is set so that the temperature characteristics of the output reference voltage Va have substantially the same temperature characteristics as the sensor 10. More specifically, the reference voltage generation circuit 20 can be set to have the same temperature characteristics as the sensor 10 by setting the Zener current of the Zener diode 21 to an appropriate value.

  FIG. 2 is a graph showing the relationship between the Zener current of the Zener diode 21 and the Zener voltage. In FIG. 2, the horizontal axis represents the Zener current (mA), and the vertical axis represents the rate of increase / decrease of the Zener voltage with respect to temperature (% / ° C.).

  As shown in the figure, the Zener diode 21 has a different influence on the temperature environment depending on the Zener current. Specifically, when the Zener current is 4 mA, the Zener voltage is reduced by 0.002% as the temperature of 1 ° C. rises. Further, the Zener diode 21 is not affected by the temperature when the Zener current is 7 mA, and when the Zener current is 9 mA, the Zener voltage increases by 0.0005% as the temperature increases by 1 ° C.

  For this reason, if the Zener current is set using the characteristics of the Zener diode 21 as shown in FIG. 2, the temperature characteristics of the reference voltage generation circuit 20 and the sensor 10 can be made substantially the same. The relationship shown in FIG. 2 is established when the ambient temperature is in the range of −25 ° C. to 75 ° C.

  The microcomputer 30 includes a reference voltage input unit 31, a correction coefficient calculation unit (calculation unit, abnormality detection unit) 32, a sensor output detection unit 33, and a correction unit (correction unit) 34.

  The reference voltage input unit 31 reads the reference voltage Va from the reference voltage generation circuit 20, performs A / D conversion (analog / digital conversion), and uses the detected amount Vad corresponding to the read reference voltage Va as a digital signal as a correction coefficient. It is configured to transmit to the calculation unit 32.

  The correction coefficient calculation unit 32 compares the detection amount Vad corresponding to the reference voltage Va from the reference voltage input unit 31 with the ideal detection amount Vat, which is an ideal value of the detection amount corresponding to the reference voltage stored in advance, and corrects the correction amount. A coefficient K (ratio of deviation between the two) is calculated. Specifically, the correction coefficient calculation unit 32 obtains the correction coefficient K from the equation: correction coefficient K = detection amount Vad / ideal detection amount Vat. Then, the correction coefficient calculation unit 32 transmits information on the correction coefficient K to the correction unit 34.

  The correction coefficient calculation unit 32 also functions as a unit that detects an abnormality in the reference voltage generation circuit 20. Here, the correction coefficient calculation unit 32 determines whether or not the value of the reference voltage Va is outside a predetermined voltage range when detecting an abnormality in the reference voltage generation circuit 20. That is, the correction coefficient calculation unit 32 determines that the value of the reference voltage Va has reached an unthinkable level based on the detected amount Vad from the reference voltage input unit 31. 20 abnormalities are detected.

  The sensor output detection unit 33 reads the output voltage Vs of the sensor 10, performs A / D conversion, and transmits the detection amount Vsd corresponding to the read main voltage Vs to the correction unit 34 as a digital signal.

  The correction unit 34 corrects the detection amount Vsd corresponding to the output voltage Vs from the sensor output detection unit 33 according to the correction coefficient K calculated by the correction coefficient calculation unit 32 to obtain a correction detection amount Vsr. . Specifically, the correction unit 34 obtains the correction detection amount Vsr from the equation: correction detection amount Vsr = detection amount Vsd × correction coefficient K.

  Here, the correction coefficient K represents the ratio of deviation between the detected amount of the reference voltage Va and the ideal detected amount Vat, and can be said to represent the reading error of the microcomputer 30. Therefore, the correction unit 34 corrects the reading (detection) error of the output voltage Vs of the sensor 10 based on the error of the reading (detection) gain obtained based on the detected amount of the reference voltage Va. . For this reason, the reading error of the microcomputer 30 is adjusted, and there is no need to adjust the resistance value of the variable resistor as in the prior art. Therefore, it can be said that the labor required for adjustment is reduced.

  The correction unit 34 is configured not to perform correction according to the correction coefficient K when the correction coefficient calculation unit 32 detects an abnormality in the reference voltage generation circuit 20. If there is an abnormality in the reference voltage generation circuit 20, it cannot be said that the obtained correction coefficient K accurately reflects the reading error of the microcomputer 30, and if correction is performed based on such a correction coefficient K, correction is performed. This is because the subsequent voltage Vsr is far from the true value.

  Next, the operation of the sensor output value detection apparatus 1 according to this embodiment will be described. FIG. 3 is a flowchart showing the operation of the sensor output value detection apparatus 1 according to this embodiment. First, when the apparatus 1 is turned on, the microcomputer 30 reads the reference voltage Va from the reference voltage generation circuit 20 (ST1). Then, the reference voltage input unit 31 reads the reference voltage Va, and outputs Vad as a detection amount corresponding to the draft Tsu Va by reference. Next, the correction coefficient calculation unit 32 of the microcomputer 30 determines whether or not the reference voltage generation circuit 20 is normal by determining whether or not the value of the reference voltage Va is outside the predetermined voltage range based on the detected amount Vad. (ST2).

  Here, when it is determined that the reference voltage generation circuit 20 is normal (ST2: YES), the correction coefficient calculation unit 32 calculates the correction coefficient K from the value of the detection amount Vad of the reference voltage Va and the ideal detection amount Vat. (ST3). The microcomputer 30 reads the output voltage Vs of the sensor 10 (ST4), and the sensor output detection unit 33 outputs a detection amount Vsd corresponding to the output voltage Vs.

  Next, the correction unit 34 obtains a correction detection amount Vsr from the detection amount Vsd and the correction coefficient K (ST5). Then, the process returns to step ST1.

  If it is determined that the reference voltage generation circuit 20 is abnormal (ST2: NO), the microcomputer 30 reads the output voltage Vs of the sensor 10 (ST6), and the sensor output detector 33 corresponds to the output voltage Vs. The detection amount Vsd is output. Next, the correction coefficient calculation unit 32 notifies the correction unit 34 that the reference voltage generation circuit 20 is abnormal (ST7). As a result, the correction unit 34 does not perform correction using the correction coefficient K. That is, the detected amount Vsd is output as it is as the corrected detected amount Vsr. Thereafter, the process returns to step ST1.

  The processes in steps ST1 to ST7 are repeated until the power of the apparatus 1 is turned off. Since the process is repeated until the power is turned off, the correction coefficient K is repeatedly obtained, and the accuracy of the correction detection amount Vsr can be improved as compared with the case where the correction coefficient K is obtained only once.

  In this way, according to the sensor output value detection apparatus 1 according to the present embodiment, the detected amount of the reference voltage Va and the ideal value of the detected amount of the reference voltage Vat are compared, and the ratio of the deviation between them is calculated. . For this reason, an error in reading (detection) gain when the microcomputer 30 reads the reference voltage Va can be clarified. Further, the detection amount of the output voltage Vs of the sensor 10 is corrected based on the obtained deviation rate. For this reason, the detection amount of the output voltage Vs of the sensor is corrected based on the error of the read gain obtained based on the detection amount of the reference voltage Va. Thus, since the error of the reading (detection) gain of the microcomputer 30 is adjusted, there is no need to provide a variable resistor and adjust the resistance value of the variable resistor.

Therefore, the labor required for adjustment can be reduced.

  Here, when the sensor 10 is a voltage sensor or a current sensor, it is known that the output voltage Vs is affected by temperature and fluctuates. In the present embodiment, the reference voltage generation circuit 20 has substantially the same temperature characteristics as the sensor 10, is provided near the sensor 10, and is exposed to a temperature environment substantially the same as the sensor 10. For this reason, the output voltage Vs of the sensor 10 and the reference voltage Va are similarly affected by temperature, and the output voltage value fluctuates. Therefore, the temperature drift can be removed without increasing the processing load of the microcomputer 30 by sensing the ambient temperature of the sensor 10 with a temperature sensor or the like.

  The reference voltage generation circuit 20 includes a Zener diode 21 and a constant current circuit 23 that supplies a constant current to the Zener diode 21. For this reason, by setting the Zener current of the Zener diode 21, the temperature characteristics of the sensor 10 and the reference voltage generation circuit 20 can be made the same. Therefore, both temperature characteristics can be easily set to be substantially the same.

  Further, when an abnormality of the reference voltage generation circuit 20 is detected, the correction unit 34 does not perform correction using the correction coefficient K. Here, when there is an abnormality in the reference voltage generation circuit 20, it cannot be said that the obtained correction coefficient K accurately reflects the reading error of the microcomputer 30, and correction is performed based on such a correction coefficient K. Then, the corrected detection amount Vsr is far from the true value. Therefore, by not performing correction as described above, it is possible to prevent a significantly erroneous detection amount Vsr from being obtained.

  As described above, the present invention has been described based on the embodiment, but the present invention is not limited to the above embodiment, and may be modified without departing from the gist of the present invention. For example, in the present embodiment, the reference voltage generation circuit 20 may have another configuration as long as it generates a reference voltage.

It is a detailed block diagram of the sensor output value detection apparatus by embodiment of this invention. 3 is a graph showing a relationship between a Zener current of a Zener diode 21 and a Zener voltage. It is a flowchart which shows operation | movement of the sensor output value detection apparatus 1 which concerns on this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Sensor output value detection apparatus 10 ... Sensor 20 ... Reference voltage generation circuit (reference voltage generation means)
21 ... Zener diode 22 ... Resistance 23 ... Constant current circuit 30 ... Microcomputer (detection means)
31: Reference voltage input unit 32: Correction coefficient calculation unit (calculation means, abnormality detection means)
33 ... Sensor output detection unit 34 ... Correction unit (correction means)

Claims (5)

In a sensor output value detection apparatus comprising: a sensor that outputs a voltage value according to a detection amount; and a detection unit that detects the detection amount based on an output voltage of the sensor.
A reference voltage generating means for outputting a reference voltage as a reference;
A calculation unit that compares a detection amount corresponding to a reference voltage output from the reference voltage generation unit with an ideal detection amount corresponding to a reference voltage stored in advance, and calculates a ratio of the deviation between the two;
Correction means for correcting the detection amount detected by the detection means based on the voltage value output from the sensor in accordance with the ratio of deviation calculated by the calculation means;
A sensor output value detection device comprising:   The reference voltage generating means has a temperature characteristic of the output reference voltage substantially the same as the temperature characteristic of the output voltage of the sensor, and is provided in the vicinity of the sensor so as to be exposed to a temperature environment substantially the same as the sensor. The sensor output value detection device according to claim 1, wherein   3. The sensor output value detection device according to claim 1, wherein the reference voltage generation unit includes a Zener diode and a constant current circuit that supplies a constant current to the Zener diode. 4. An abnormality detection means for detecting an abnormality of the reference voltage generation means;
The correction means does not perform correction according to the deviation ratio calculated by the calculation means when the abnormality detection means detects an abnormality of the reference voltage generation means. Item 4. The sensor output value detection device according to any one of Items 3 to 4. The abnormality detection means determines that the reference voltage generation means is abnormal when the value of the voltage from the reference voltage generation means is outside a predetermined voltage range. 5. The sensor output value detection device according to 4.

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