JP4613643B2 - Temperature measuring device - Google Patents

Description

  The present invention relates to a temperature measuring device.

  Conventionally, this type of temperature measuring device includes a resistance temperature detector (see FIG. 2) whose resistance value changes approximately exponentially while the temperature of the object to be measured changes linearly, and a resistance temperature detector, Equipped with one constant resistor connected in series and a control unit including an AD converter (AD converter) that reads changes in voltage at approximately equal intervals, and calculates the measured temperature based on the voltage across the resistance temperature detector To do. However, the resistance value of the resistance temperature detector changes in a non-linear manner, resulting in a difference between the high resolution area (area where fine changes can be read) and the low resolution area (area where only coarse changes can be read). There was a problem that appeared large. Further, in the case of a temperature measuring device that calculates the measured temperature based on the voltage across the constant resistance, as shown in FIG. 7, the high resolution region (C1 in FIG. 7) and the low resolution region ( There is a problem that the difference between C2 and C3) in FIG. For example, when the resistance value of the constant resistance is 5.15 kΩ, the rate of change of the voltage across the constant resistance in the low resolution region is about 0.6 mV / ° C.

In order to solve the above-described problem, a temperature measurement device is provided that has a low resolution region and has a measurement resolution of a certain level or more over the entire temperature range. For example, in Patent Document 1, when a control device determines that the current temperature has reached a high temperature region with low measurement resolution, a series circuit of a constant resistor (fixed resistor) connected in series with a resistance temperature detector Among these, there is disclosed a temperature measuring device that controls the open / closed states of a plurality of switch means so as to selectively close (turn on) a series circuit to which a constant resistance having a low resistance value belongs. As a result, the temperature characteristic of the output voltage is changed to a steep slope that can improve the measurement resolution. Therefore, a resistance temperature detector whose resistance value decreases approximately exponentially as the temperature increases linearly is used. Even in such a case, the measurement resolution in the high temperature region can be improved and the measurement temperature can be calculated. Patent Document 2 discloses a temperature measuring device (temperature measuring device) that uses a resistance temperature detector and stores a conversion table to correct the measured temperature.
JP-A-10-239171 (pages 4 and 5 and FIG. 1) Japanese Patent Laid-Open No. 7-151612 (page 3 and FIG. 1)

  However, although the temperature measurement device of Patent Document 1 switches the constant resistance when it is in the low resolution region, the measurement resolution is not optimized for each measurement region corresponding to each constant resistance. There was a problem that a new constant resistance had to be added each time the voltage dropped. In addition, since there is a dead zone (a region that cannot be read as a change in voltage value even if the temperature changes) between the two measurement regions, there is a problem that the accuracy deteriorates. It was.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a temperature measurement device capable of efficiently increasing measurement resolution without providing a dead zone.

According to the first aspect of the present invention, the resistance value of the resistance temperature sensor changes approximately exponentially when the temperature changes linearly, and the resistance value of the resistance temperature sensor at both end temperatures becomes a geometric series. As described above, a predetermined temperature region is divided into a plurality of measurement regions, and a measurement value is input, and a measurement temperature is calculated based on the measurement value, or the measurement value is regenerated by switching the measurement region. Control means for determining whether to input, a plurality of constant values corresponding to the different measurement areas , each having a resistance value having a magnitude between the minimum value and the maximum value of the resistance temperature detector in the corresponding measurement area. A resistance , and an auxiliary resistance having a resistance value that is approximately the square root of the product of the resistance values of two constant resistances corresponding to adjacent measurement regions, and the control means includes the plurality of constant resistances and the auxiliary resistance. The function of selectively connecting in series with the resistance temperature detector Then, in the auxiliary measurement region in a predetermined range among the adjacent measurement regions, voltages at both ends of two constant resistances corresponding to the adjacent measurement regions are input as the measurement values, and the constant measurement is performed based on the measurement values. A temporary measurement temperature by resistance is calculated, a voltage across the auxiliary resistor is input as the measurement value, a temporary measurement temperature by the auxiliary resistance is calculated based on the measurement value, and a temporary measurement temperature by the constant resistance and the auxiliary resistance are calculated. The average value with the temporary measurement temperature is used as the measurement temperature .

In this configuration, since the rate of change of the corresponding constant resistance with respect to the temperature change in each measurement region can be increased, the measurement resolution can be increased efficiently without providing a dead zone. In this configuration, the portion with the highest measurement resolution in the auxiliary measurement region can be set near the boundary of the measurement region, so that the measurement resolution can be increased. Even when a white reading error occurs, the error factor can be reduced by an average value of the temporary measurement temperature by the constant resistance and the temporary measurement temperature by the auxiliary resistance.

  According to a second aspect of the present invention, in the first aspect of the present invention, the control unit divides the predetermined temperature region into three or more measurement regions, and the resistance values of the plurality of constant resistances are determined. It is characterized by being a geometric series. In this configuration, the resistance values of the plurality of constant resistances are set in a geometric series, so that the measurement resolution can be further increased.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein the resistance value of each constant resistance is substantially equal to the resistance value of the resistance temperature detector at an intermediate temperature of the corresponding measurement region. It is characterized by. In this configuration, the range of the magnitude of the voltage across each constant resistor can be made substantially the same, so that the measurement resolution can be further increased. Further, the measurement resolution on the high temperature side and the low temperature side in each measurement region can be made equal.

According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects of the present invention, the control means is arranged in the boundary region of a predetermined range among the adjacent measurement regions, in the adjacent measurement region. The voltage across the two corresponding constant resistances is input as the measurement value, and the temporary measurement temperature by the constant resistance is calculated based on each input measurement value. For the calculated temporary measurement temperature by the two constant resistances, A weight set so as to become smaller as it approaches each other measurement region side is given, and an average value of provisional measurement temperatures by two weighted constant resistances is set as the measurement temperature. With this configuration, when the temperature is measured beyond the measurement area, the measurement temperature can be calculated without the user being aware of the boundary of the measurement area. In addition, the you completely prevent dead zone, it is possible to measure the measured temperature with higher accuracy in the vicinity of the boundary region.

According to a fifth aspect of the present invention, in the first aspect of the present invention, the auxiliary resistance is provided in all of the adjacent measurement areas, and the control means assists a predetermined range of the adjacent measurement areas. The determination is performed in all measurement areas. In this configuration, in all the adjacent measurement areas, the portion with the highest measurement resolution of the auxiliary measurement area can be set near the boundary of the measurement area, so that the measurement resolution can be increased.

The invention according to claim 6 is the invention according to claim 1 or 5 , wherein the control means sets the adjacent auxiliary measurement region in the auxiliary boundary region within a predetermined range among the adjacent auxiliary measurement regions. The voltage across the two corresponding auxiliary resistors is input as the measured value, and the temporary measurement temperature by the auxiliary resistor is calculated based on each input measurement value, and the calculated temporary measurement temperature by the two auxiliary resistors is calculated. A weight set so as to become smaller as it approaches the other auxiliary measurement region side, an average value of temporary measurement temperatures by two weighted auxiliary resistances, and a measurement value that is a voltage across the constant resistance An average value with a temporary measurement temperature by a constant resistance calculated based on is used as the measurement temperature. In this configuration, when the temperature is measured beyond the boundary temperature of the auxiliary measurement area, the measurement value can be changed smoothly with respect to the temperature change, so the user can measure without being aware of the boundary of the auxiliary measurement area. The temperature can be calculated. In addition, since there is no dead zone, the measurement temperature can be measured with high accuracy even in the vicinity of the auxiliary boundary region.

The invention according to claim 7 is the invention according to any one of claims 1 to 6 , wherein the control means switches between a standard voltage and the measured value and inputs the standard voltage and the measured value. The measurement temperature is calculated .

  According to the present invention, the measurement resolution can be efficiently increased without providing a dead zone.

( Basic form )
First, a basic configuration of the basic form will be described with reference to FIGS. As shown in FIG. 1, the basic form temperature measuring apparatus includes a resistance temperature detector 1, a plurality of constant resistances 2, and a control unit 3.

The resistance temperature detector 1 is, for example, a NTC (Negative Temperature Coefficient) thermistor or the like, and is connected to a DC voltage source (not shown) at one end and to a plurality of constant resistors 2 at the other end. The DC voltage source supplies a DC voltage Vcc. As shown in FIG. 2, the resistance temperature detector 1 has a characteristic that the resistance value decreases approximately exponentially as the temperature of the measurement target increases linearly. The resistance value of the resistance thermometer 1 of the basic form is 1000 kΩ at 0 ° C., and increases 0.9 times every time the temperature rises by 1 ° C., and 0.0265 kΩ at 100 ° C. The temperature measuring range of the resistance temperature detector 1 is 0 to 100 ° C. The resistance value and the temperature measurement range of the resistance temperature detector 1 are not limited to the above, and are appropriately selected according to the application.

  The plurality of constant resistances 2 include three constant resistances 20, 21, and 22, as shown in FIG. Each constant resistance 20, 21, 22 is connected in series with the resistance temperature detector 1 on one end side, and connected in series with switches 40, 41, 42 described later on the other end side. Each of the constant resistors 20, 21, 22 corresponds to a measurement region set by the microcomputer 8, and outputs the both-end voltage Va as a measurement value to the AD converter 7. The resistance values rA1, rA2, and rA3 of the constant resistances 20, 21, and 22 are substantially equal to the resistance value of the resistance temperature detector 1 at the intermediate temperature in the corresponding measurement region, and are sequentially 172.3 kΩ, 5.15 kΩ, 0 154 kΩ (see FIG. 3). That is, it is set to the same value as the logarithmic central value of the resistance value of the resistance temperature detector 1 in each measurement region. For example, the resistance value rA1 of the constant resistance 20 is the same resistance value as R in FIG. rA1 = 1000 ÷ ((1000 ÷ 0.0265) 1/3) 1/2 (kΩ). The resistance values rA1, rA2, and rA3 of the constant resistors 20, 21, and 22 are geometric series, the resistance value rA2 of the constant resistor 21 is about 33.4 times the resistance value rA3 of the constant resistor 22, The resistance value rA1 of the constant resistance 20 is about 33.5 times the resistance value rA2 of the constant resistance 21. Thereby, the measurement resolution of the high temperature region and the low temperature region can be made substantially equal in each measurement region. The resistance values rA1, rA2, and rA3 of the constant resistances 20, 21, and 22 may be between the minimum value and the maximum value of the resistance temperature detector 1 in the corresponding measurement region. Even with this setting, the measurement resolution can be increased.

  As shown in FIG. 1, the control unit 3 includes a plurality of switches 4, a reference voltage generation unit 5, a standard voltage generation unit 6, an AD converter 7, and a microcomputer (hereinafter referred to as “microcomputer”) 8. I have.

  The plurality of switches 4 includes three switches 40, 41 and 42. Each switch 40, 41, 42 is connected in series with the constant resistances 20, 21, 22 on one end side and grounded on the other end side, and is switched on and off by the microcomputer 8.

  The reference voltage generation unit 5 connects two resistors 50 and 51 in series, divides a DC voltage Vcc supplied from a DC voltage source (not shown), and uses the divided DC voltage as a reference voltage for an AD converter. 7 is output.

  The standard voltage generator 6 includes two resistors (voltage dividing resistors) 60 and 61 and a switch 62. The resistors 60 and 61 have a certain resistance value and are connected in series, and divide the DC voltage Vcc supplied from a DC voltage source (not shown). The switch 62 is connected to an input port 70 of an AD converter 7 to be described later on one end side, and connected between the resistor 60 and the resistor 61 on the other end side, and is switched on and off by the microcomputer 8. When the switch 62 is turned on, the DC voltage divided by the resistors 60 and 61 is output to the input port 70 as a standard voltage.

  The AD converter 7 is formed of, for example, an IC or the like, and has an input port 70 connected to one end side of the constant resistors 20, 21, and 22 and the standard voltage generator 6, and an output connected to the microcomputer 8. A port 71 and a reference voltage input port 72 connected to the reference voltage generator 5 are provided. The AD converter 7 inputs the voltage Va across the constant resistances 20, 21, and 22 obtained by dividing the DC voltage Vcc by the resistance temperature detector 1 and the constant resistances 20, 21, and 22 into the input port 70 as a measured value. The voltage Va is converted from an analog value to a digital value by equally dividing or multiplying the voltage.

  However, an internal resistor 73 exists in the internal circuit connected to the reference input voltage port 72. The internal resistance 73 has a greater influence than an internal resistance (not shown) of an internal circuit connected to the input port 70. That is, when looking at the AD converter 7, the internal impedance of the input port 70 is larger than the internal impedance of the reference voltage input port 72. Further, when the AD converter 7 is formed of an IC, the internal resistor 73 has a large variation in resistance value and a poor characteristic with respect to a temperature change. For this reason, when the DC voltage is input from the reference voltage generator 5 as the reference voltage, the AD converter 7 has a problem in that the variation in the internal resistance 73 causes a variation in the reference voltage and the measurement accuracy deteriorates. It was.

  In order to solve the above problem, the AD converter 7 inputs (reads) a DC voltage from the standard voltage generator 6 to the input port 70. By using the input DC voltage as a standard voltage, even if the resistance value of the internal resistor 73 varies greatly, the reference voltage is calculated based on the standard voltage, and the true reference voltage is calculated. Yes.

  The AD converter 7 may include a plurality of input ports. With such a configuration, it is possible to input the voltages across the plurality of constant resistors 2 and the standard voltage of the standard voltage generator 6 from different input ports.

  As shown in FIG. 3, the microcomputer 8 divides a predetermined temperature region (0 to 100 ° C. in FIG. 3) into three measurement regions A1, A2, and A3. The three measurement areas A1, A2 and A3 are divided so that the resistance value of the resistance temperature detector 1 at the temperature at both ends of each of the measurement areas A1, A2 and A3 becomes a geometric series (logarithmically equal). Yes. That is, the resistance value of the resistance thermometer 1 when the temperature is 0 ° C., T1, T2, and 100 ° C. becomes a geometric series (see a1, a2, and a3 in FIG. 3). As shown in FIG. 1, the microcomputer 8 is connected to an AD converter 7 and inputs a digital value converted from an analog value of the voltage Va at both ends from the AD converter 7 and measures based on the input digital value. Control means for calculating temperature or switching each of the constant resistances 20, 21, and 22 to switch between the measurement areas A1, A2, and A3 (see FIG. 3) and re-inputting the both-end voltage Va It is.

Next, the operation of the basic form temperature measuring apparatus will be described. First, the initial setting will be described. The microcomputer 8 switches the plurality of switches 4 to turn on the constant resistor 21 and turn off the constant resistors 20 and 22. The reference voltage is input to the reference voltage input port 72 and the standard voltage is input to the input port 70 by the AD converter 7. The standard voltage is converted from an analog value to a digital value, and the internal resistance 73 is estimated based on the converted digital value. A true reference voltage is calculated based on the estimated internal resistance 73. Subsequently, a description will be given after the initial setting. The voltage Va across the constant resistor 21 is input to the input port 70. A comparison is made by dividing the reference voltage by equal division or equal magnification with respect to the both-end voltage Va. Based on the comparison result, the both-end voltage Va is converted from an analog value to a digital value and output to the microcomputer 8. Next, the microcomputer 8 compares the both-ends voltage Va converted into a digital value with the minimum voltage and the maximum voltage (see FIG. 4) in the measurement region. When the both-end voltage Va is not less than the minimum voltage and not more than the maximum voltage, the measured temperature is calculated based on the both-end voltage Va. On the other hand, when the both-end voltage Va is smaller than the minimum voltage, the plurality of switches 4 are switched, the constant resistance 20 having a resistance value larger than the current value is switched to the low temperature side, and the AD converter 7 re-inputs the both-end voltage Va. . When the both-end voltage Va is larger than the maximum voltage, the plurality of switches 4 are switched, the constant resistance 22 having a resistance value smaller than the current value is switched to bring the measurement region to the high temperature side, and the AD converter 7 re-inputs the both-end voltage Va. By repeating the above steps, the measured temperature can be calculated continuously.

As described above, according to the basic form , the rate of change with respect to the temperature change of the voltage Va across the corresponding constant resistance 20, 21, 22 can be increased in each measurement region A1, A2, A3. Measurement resolution can be increased efficiently. Further, since the resistance values rA1, rA2, and rA3 of the plurality of constant resistors 20, 21, and 22 are set in a geometric series, the measurement resolution can be further increased. Further, since the range of the magnitude of the voltage Va at both ends can be made substantially the same in each measurement region A1, A2, A3, the measurement resolution can be further increased and the high temperature in each measurement region A1, A2, A3 can be increased. The measurement resolution of the region and the low temperature region can be made equal.

As a modification of the basic form , the resistance temperature detector is a PTC (Positive Temperature Coefficient), for example, and has a characteristic that the resistance value decreases approximately exponentially as the temperature of the measurement target increases linearly. It may be. Even if it is such a structure, the effect similar to a basic form can be acquired.

Further, as another modification of the basic form , instead of inputting the voltage across the constant resistance to the AD converter, the voltage across the resistance temperature detector may be inputted into the AD converter. Even if it is such a structure, the effect similar to a basic form can be acquired.

The temperature measuring device of the other basic form, similar to the temperature measuring device of the basic embodiment (see FIG. 1), and the temperature measuring resistor 1, although a plurality of the constant resistance 2, the temperature measuring device of the basic form There are some features that are not described below.

In the control unit 3 (see FIG. 1) of another basic form , the microcomputer 8 has a temperature measurement range (temperature in FIG. 5) in two adjacent measurement regions (see A1 and A2 in FIG. 5) as shown in FIG. The measurement range C1 and the temperature measurement range C2) are expanded, and a boundary region (see B1 in FIG. 5) which is a predetermined overlapping range among the measurement regions is provided. Similarly, the microcomputer 8 sets a boundary region that is a predetermined overlapping range of the measurement regions A2 and A3 in the two adjacent measurement regions A2 and A3 (see FIG. 4). For example, the operation of the microcomputer 8 in the boundary region B1 provided between the measurement region A1 and the measurement region A2 will be described. First, the both-ends voltage of the constant resistance 21 corresponding to the measurement region A2 is input, and the temporary measurement temperature Ta2 by the constant resistance 21 is calculated based on the both-ends voltage. Subsequently, the both-ends voltage of the constant resistance 20 corresponding to the measurement region A1 is input, and the temporary measurement temperature Ta1 by the constant resistance 20 is calculated based on the both-ends voltage. Next, a weight P2 set so as to decrease as it approaches the measurement region A1 side is applied to the temporary measurement temperature Ta2 by the constant resistance 21. The weight P2 is lightly increasing distance from the boundary temperature T1 for the portion exceeding the measurement area A2 in a temperature measurement range C2, heavier increasing distance from the boundary temperature T1 for a portion at a temperature measurement range C2 do not exceed the measurement region A2. That is, the weight is continuously changed. On the other hand, a weight P1 set so as to decrease as it approaches the measurement region A2 side is applied to the temporary measurement temperature Ta1 by the constant resistance 20. The weights P1 is lightly increasing distance from the boundary temperature T1 for a portion at a temperature measurement range C1 exceeds the measurement region A1, heavier increasing distance from the boundary temperature T1 for a portion at a temperature measurement range C1 does not exceed the measurement region A1. That is, the weight is continuously changed. The average value of the provisional measurement temperature Ta1 with the weighted constant resistance 20 and the provisional measurement temperature Ta2 with the constant resistance 21 is defined as the measurement temperature Ta. In addition, the control part 3 of another basic form is the same as the control part 3 of a basic form except the above.

  As a result, even if each constant resistance is an error within the allowable range at the boundary point of the measurement region, it is possible to prevent discontinuous points from appearing in the temperature change, and to smoothly connect the boundary points. Therefore, the user can use this temperature measuring device without being aware of the boundary. Further, since no dead zone or discontinuous points are generated, the temperature accuracy at the boundary of the measurement region is not deteriorated.

As described above, according to the other basic forms , the same effect as the basic form can be obtained, and when the temperature is measured beyond the measurement area, the measurement temperature is calculated without the user being aware of the boundary of the measurement area. can do. Moreover, since there is no dead zone, the measurement temperature can be measured with high accuracy even in the vicinity of the boundary region.

(Embodiment 1 )
Temperature measuring apparatus according to the first embodiment, similar to the temperature measuring device of the basic embodiment (see FIG. 1), and the temperature measuring resistor 1, and a plurality of fixed resistors 2, a temperature measuring device of the basic form There are no features described below.

The temperature measurement device according to the present embodiment includes a plurality (two in the present embodiment ) of auxiliary resistors (not shown). Each auxiliary resistor is connected in series with the resistance temperature detector 1 (see FIG. 1) on one end side in parallel with the constant resistors 20, 21, 22 (see FIG. 1), and an auxiliary switch ( (Not shown) and connected in series. Each auxiliary resistor corresponds to an auxiliary measurement region set by the microcomputer 8 (see FIG. 1), and outputs the voltage Va between both ends as a measured value to the AD converter 7 (see FIG. 1). Also, the resistance values rB1, rB2 of each auxiliary resistor are the abbreviations of the product of the resistance values rA1, rA2, rA3 of the two constant resistances 20, 21, 22, corresponding to the adjacent measurement regions A1, A2, A3 to be supported. It is a square root value, and rB1 = (171.2 × 5.15) 1/2 = 29.8 (kΩ), rB2 = (5.15 × 0.154) 1/2 = 0.88 (kΩ) .

Further, in the control unit 3 (see FIG. 1) of the present embodiment , as shown in FIG. 6, the microcomputer 8 has an auxiliary measurement region (FIG. 6) in a predetermined range among the adjacent measurement regions A1, A2, and A3. T3-T4, T4-T5), provisional measurement with constant resistance based on voltage V1, V2, V3 across two constant resistances 20, 21, 22 corresponding to adjacent measurement areas A1, A2, A3 An average value of the temperature Tb1 and the provisional measurement temperature Tb2 by the auxiliary resistance based on the both-end voltages V4 and V5 of the auxiliary resistance (not shown) is defined as the measurement temperature Tb. In addition, the control part 3 of this embodiment is the same as that of the control part 3 of a basic form except the above.

As described above, according to the present embodiment , the same effect as that of the basic embodiment can be obtained, and the auxiliary measurement region (between T3 and T4 in FIG. 6, between T4 and T5) has the highest measurement resolution (in FIG. 6). T1, T2 portion) can be set in the vicinity of the boundary where the measurement resolution of the measurement areas A1, A2, A3 is the lowest, and between the measurement areas A1, A2, A3 and the auxiliary measurement areas (between T3-T4, The temperature can be measured twice between T4 and T5, and the average of them can be taken, so that the measurement resolution can be increased. Even when a white reading error occurs, the provisional measurement temperature Tb1 by the constant resistance based on the voltages V1, V2, and V3 across the constant resistances 20, 21, and 22, and the voltages V4 and V5 across the auxiliary resistance. The error factor can be reduced by the average value with the temporary measurement temperature Tb2 by the auxiliary resistance based on the above.

(Embodiment 2 )
Similar to the temperature measurement device of the first embodiment, the temperature measurement device of the second embodiment includes a resistance temperature detector 1 (see FIG. 1), a plurality of constant resistors 2 (see FIG. 1), and a plurality of auxiliary resistors (see FIG. 1). However, the temperature measuring device of the first embodiment has the following characteristic part.

In the control unit 3 (see FIG. 1) of the present embodiment , the microcomputer 8 (see FIG. 1) is not a simple arithmetic average, but a temporary measurement temperature by a constant resistance according to the linearity of the measurement region and the auxiliary measurement region. And the temporary measured temperature by the auxiliary resistor are weighted and averaged, and the average value is used as the measured temperature. In addition, the control part 3 of this embodiment is the same as that of the control part 3 of Embodiment 1 in points other than the above.

As described above, according to this embodiment , the same effect as that of Embodiment 1 can be further increased.

(Embodiment 3 )
Similar to the temperature measurement device of the first embodiment, the temperature measurement device of the third embodiment includes a resistance temperature detector 1 (see FIG. 1), a plurality of constant resistors 2 (see FIG. 1), and a plurality of auxiliary resistors (see FIG. 1). However, the temperature measuring device of the first embodiment has the following characteristic part.

In the control unit 3 (see FIG. 1) of the present embodiment , the microcomputer 8 (see FIG. 1) expands the temperature measurement range in two adjacent auxiliary measurement areas (between T3-T4 and T4-T5 in FIG. 6). In the auxiliary measurement area (between T3 and T4, between T4 and T5), an auxiliary boundary area having a predetermined overlapping range is provided. In the auxiliary boundary region, voltages V4 and V5 (see FIG. 6) of auxiliary resistors (not shown) corresponding to the respective auxiliary measurement regions (between T3 and T4, between T4 and T5) are input, and the both end voltages are input. Based on V4 and V5, provisional measurement temperatures Tc1 and Tc2 by the auxiliary resistance are calculated. Next, a weight set so as to become smaller as it approaches the other auxiliary measurement region side is given to the temporary measurement temperatures Tc1 and Tc2 by the two input auxiliary resistors. Temporary measurement temperature Tc3 by the constant resistance based on the average value of the temporary measurement temperatures Tc1 and Tc2 by the two weighted auxiliary resistors and the voltages V1, V2 and V3 across the constant resistances 20, 21, and 22 (see FIG. 6). The average value is taken as the measurement temperature Tc. In addition, the control part 3 of this embodiment is the same as that of the control part 3 of Embodiment 1 in points other than the above.

As described above, according to the present embodiment , when the temperature is measured beyond the boundary temperature of the auxiliary measurement region (between T3 and T4 in FIG. 6, between T4 and T5), the measurement value changes smoothly with respect to the temperature change. Therefore, the measurement temperature Tc can be calculated without the user being aware of the boundary of the auxiliary measurement region (between T3 and T4, between T4 and T5). In addition, since there is no dead zone, the measurement temperature Tc can be measured with high accuracy even in the vicinity of the auxiliary boundary region. Furthermore, since the range in which the measurement areas A1, A2, A3 and the auxiliary measurement areas (between T3-T4 and T4-T5) overlap can be expanded, the same effect as in the first embodiment can be further increased. Can do.

( Reference Example 1 )
In Reference Example 1 , the change rate of the voltage at both ends with respect to the temperature is measured by changing the resistance value rA1 of the constant resistance 20 in the temperature measurement device of the basic form .

  First, if the resistance value rA1 is 29.9 kΩ, which is substantially the same as the minimum value of the resistance temperature detector 1 in the measurement region A1, the rate of change of the both-end voltage Va in the low resolution region in the measurement region A1 is about 3.1 mV. / ° C. The same result is obtained when the resistance value rA1 is set to 1000 kΩ, which is the same resistance value as the maximum value of the resistance temperature detector 1. Preferably, if the resistance value rA1 is 345 kΩ, which is approximately the same resistance value as the resistance value of the resistance temperature detector 1 at the intermediate temperature of the measurement region A1, the change rate is about 8.1 mV / It becomes ℃. The same result is obtained when the resistance value rA1 is set to 86.5 kΩ, which is substantially the same as the resistance value obtained by halving the resistance value of the resistance temperature detector 1 at the intermediate temperature in the measurement region A1. More preferably, when the resistance value rA1 is 173 kΩ, which is substantially the same as the resistance value of the resistance temperature detector 1 at the intermediate temperature in the measurement region A1, the rate of change is about 13.7 mV / ° C.

As described above, according to this reference example, when the resistance value of the constant resistance is set to a value between the minimum value and the maximum value of the resistance temperature detector in the corresponding measurement region, The rate of change can be increased. In particular, when the resistance value of the resistance temperature detector 1 at an intermediate temperature in the measurement region is equal to or greater than a value obtained by halving the resistance value of the resistance temperature detector 1, the voltage across the voltage Since the rate of change exceeds 3.5 mV / ° C., it is possible to obtain a rate of change that can be measured accurately with respect to the voltage range (0 to 1 V) at both ends. Furthermore, if the resistance value is substantially the same as the resistance value of the resistance temperature detector 1 at the intermediate temperature in the measurement region, the rate of change can be dramatically increased.

As a modification of this reference example , the resistance values rA2 and rA3 of the constant resistances 21 and 22 are set in the measurement regions A2 and A3 by the same method as the resistance value rA1 of the constant resistance 20, respectively. Can do. If it does in this way, the effect similar to this reference example can be acquired in measurement area | region A2, A3.

( Reference Example 2 )
The temperature measuring device of the reference example 2 includes the resistance temperature detector 1 as in the temperature measuring device of the basic form (see FIG. 1), but the following characteristic portions not included in the temperature measuring device of the basic form There is.

The plurality of constant resistances (see FIG. 1) of this reference example have two constant resistances. Each constant resistance corresponds to a measurement region set by the microcomputer 8. The plurality of constant resistances 2 in this reference example are the same as the plurality of constant resistances 2 in the basic form except for the above.

In the temperature measurement device of this reference example , the microcomputer 8 divides a predetermined temperature region into two measurement regions. The two measurement regions are divided so that the resistance values of the resistance temperature detectors at the temperature at both ends of each measurement region are geometric series. That is, the resistance value of the resistance temperature detector at 0, 50, and 100 ° C. becomes a geometric series. The microcomputer 8 of this reference example is the same as the microcomputer 8 of the basic form except for the points described above.

Next, the change rate of the both-ends voltage with respect to the temperature in the low resolution region when the resistance value of the constant resistance is changed in the low temperature side measurement region of the temperature measuring device of this reference example will be described. First, assuming that the resistance value of the constant resistance is 143 kΩ, which is substantially the same resistance value as the resistance value of the resistance temperature detector doubled at the intermediate temperature in the measurement region, the rate of change is about 3.7 mV / ° C. It becomes. The same result is obtained when the resistance value of the constant resistance is set to 36 kΩ, which is substantially the same as the resistance value obtained by halving the resistance value of the resistance temperature detector at the intermediate temperature in the measurement region. Preferably, if the resistance value of the constant resistance is 71.8 kΩ, which is substantially the same as the resistance value of the resistance temperature detector at the intermediate temperature of the measurement region, the rate of change is about 6.9 mV / ° C.

As described above, according to this reference example , even when the predetermined temperature region is divided into two measurement regions, the resistance value of the resistance thermometer 1 at the intermediate temperature of the measurement region is halved. If the resistance value is equal to or greater than the resistance value of the resistance temperature detector 1, the voltage change rate at both ends in the low resolution region can be 3.5 mV / ° C. or more. It is possible to obtain a rate of change that can be accurately measured with respect to the range (0 to 1 V). Furthermore, when the resistance value is substantially the same as the resistance value of the resistance temperature detector at the intermediate temperature in the measurement region, the rate of change can be greatly increased.

As a modification of the present reference example , even in a constant resistance corresponding to the high temperature side measurement region, the resistance value can be set by the same method as the constant resistance corresponding to the low temperature side measurement region. If it does in this way, the effect similar to this reference example can be acquired in the measurement area | region of a high temperature side.

It is a circuit diagram of a temperature measuring device. In a temperature measuring device same as the above, it is a linear diagram showing the relation between temperature and resistance value of a resistance temperature detector. In a temperature measuring device same as the above, it is a logarithm figure showing the relation between temperature and resistance value of a resistance temperature detector. In a temperature measuring apparatus same as the above, it is a figure showing the relationship between temperature and the voltage of both ends of a constant resistance. In temperature measuring device is a diagram representing the weight of the auxiliary measurement region. In the temperature measuring device of Embodiment 1 by the present invention, it is a figure showing the relation between temperature and the both-ends voltage of constant resistance and auxiliary resistance. It is a figure showing the relationship between temperature and the voltage of both ends of a constant resistance in the conventional temperature measuring device.

1 RTD 2 Multiple constant resistance 4 Multiple switches 7 AD converter 8 Microcomputer

Claims (7)

A resistance temperature detector whose resistance value changes approximately exponentially when the temperature changes linearly,
A predetermined temperature region is divided into a plurality of measurement regions so that the resistance value of the resistance temperature detector at both end temperatures becomes a geometric series, and the measurement value is input and measured based on the measurement value. A control means for determining whether to calculate temperature or switch the measurement region and re-input the measurement value ;
A plurality of constant resistances corresponding to the different measurement areas, each having a resistance value having a magnitude between a minimum value and a maximum value of the resistance thermometer in the corresponding measurement area ;
An auxiliary resistor having a resistance value that is approximately the square root of the product of the resistance values of two constant resistances corresponding to adjacent measurement regions ;
The control means has a function of selectively connecting the plurality of constant resistances and the auxiliary resistors in series with the resistance temperature detector, and an auxiliary measurement region in a predetermined range among the adjacent measurement regions The voltage across the two constant resistances corresponding to the adjacent measurement regions is input as the measurement value, the temporary measurement temperature by the constant resistance is calculated based on the measurement value, and the voltage across the auxiliary resistance is measured A temporary measurement temperature by the auxiliary resistance is calculated based on the measured value and the average value of the temporary measurement temperature by the constant resistance and the temporary measurement temperature by the auxiliary resistance is used as the measurement temperature. Temperature measuring device. The control means divides the predetermined temperature region into three or more measurement regions;
The temperature measuring apparatus according to claim 1, wherein the resistance values of the plurality of constant resistances are geometric series.   The temperature measuring device according to claim 1 or 2, wherein a resistance value of each constant resistance is substantially equal to a resistance value of the resistance temperature detector at an intermediate temperature of the corresponding measurement region.   The control means inputs, as the measurement value, both-end voltages of two constant resistances corresponding to the adjacent measurement region in a boundary region of a predetermined range among the adjacent measurement regions, and each input measurement value The temporary measurement temperature with constant resistance is calculated based on the above, and the calculated temporary measurement temperatures with two constant resistances are weighted so as to decrease as they approach each other measurement area, and weights are assigned. The temperature measuring device according to any one of claims 1 to 3, wherein an average value of provisional measurement temperatures obtained by the two constant resistances is set as the measurement temperature. The auxiliary resistance is provided in all adjacent measurement areas,
Said control means, said all of the auxiliary measurement region of a predetermined range of the adjacent measurement regions, a temperature measuring device according to claim 1, characterized in that to perform said determination. Before SL control means inputs Oite auxiliary boundary area of a predetermined range of the next adjacent auxiliary measuring region, the two voltage across the auxiliary resistance corresponding to the auxiliary measurement region where the adjacent as the measurement value Based on each input measurement value, the temporary measurement temperature by the auxiliary resistance is calculated, and the calculated temporary measurement temperature by the two auxiliary resistances is set so as to become smaller as it approaches the other auxiliary measurement region side. The average value of the temporary measured temperature by the two auxiliary resistors weighted and the average value of the temporary measured temperature by the constant resistance calculated based on the measured value that is the voltage across the constant resistance the temperature measuring device according to claim 1 or 5, wherein the to the measured temperature. The temperature measurement according to any one of claims 1 to 6, wherein the control means switches between a standard voltage and the measured value and calculates the measured temperature from the standard voltage and the measured value. Equipment .

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