Temperature sensor module

Abstract

One temperature sensor module (100), comprising: a temperature sensor element (1) whose resistance value changes according to the temperature of a target medium; and a signal processing circuit (2) which is connected to the temperature sensor element (1) and which outputs an electrical signal which correlates with the resistance value of the temperature sensor element (1), wherein the signal processing circuit (2) comprises a series connection resistor (3) which is connected in series with the temperature sensor element (1) and whose resistance value changes according to a command signal that has been transmitted, a temperature detection circuit (4) that detects and outputs a temperature of the signal processing circuit (2), a first analog-to-digital conversion circuit (5) that converts an output signal from the temperature detection circuit (4) into a digital signal and outputs the digital signal a memory (7) which stores a series connection resistance data element about a relationship between a temperature and the resistance value of the series connection resistor (3), a digital signal processing circuit (6) which uses the series connection resistor data element stored in the memory (7) to calculate a digital command signal on the basis of the digital signal indicating the temperature of the signal processing circuit (2) in order to maintain the resistance value of the series connection resistor (3) at a constant value, and outputs the digital command signal, and a digital-to-analog conversion circuit (8) that converts the digital command signal into an analog command signal and outputs the analog command signal to the series connection resistor (3).

Description

Background of the invention 1. Field of the invention

[0001] The present disclosure relates to a temperature sensor module. 2. Description of the state of the art

[0002] Resistance thermometers, whose resistance values ​​change with temperature, are used as temperature sensors. Platinum resistors and NTC thermistors (temperature sensors) are examples of resistance thermometers. One method for detecting temperature using a resistance thermometer involves connecting a resistance thermometer and another resistive element in series, applying a predetermined supply voltage to both ends, and obtaining an output voltage corresponding to a change in temperature from a junction between the resistance thermometer and the resistive element.

[0003] To measure a temperature with high accuracy using a resistance thermometer, the following measures must be taken: a measure to use a resistance element with low tolerance and high accuracy as a resistance element to be connected to the resistance thermometer; a measure to add a circuit and linearize an output voltage obtained from a connection point; or something similar.

[0004] As an example where the accuracy of a temperature measurement using a resistance thermometer is highly developed, the following configuration is described: a configuration in which a temperature sensor element and a resistance element are connected in series in an integrated circuit, a signal at a connection point between them is subjected to a correction process using information about the resistance value of the resistance element stored in a memory in the integrated circuit to correct for fluctuations in the resistance value of the resistance element, and adjustment (bending) of a property due to the temperature sensor element being corrected by a digital calculation through a correction process section (see, for example, JP 2014 - 102 218 A).

[0005] DE 694 25 933 T2 discloses a device for measuring the temperature prevailing in an area to be monitored. This device comprises a measuring chain supplied with a supply voltage and means for processing a measurement signal, which includes an analog-to-digital converter. The device according to the invention is characterized in that it further comprises a plurality of resistors connected in series, which are arranged in the measuring chain, and a selection means which serves to select a reference voltage from a plurality of voltages tapped at a point of the plurality of resistors and to supply this selected reference voltage to the converter.

[0006] DE 695 04 537 T2 discloses a method for temperature sensing using a sensor with a negative temperature coefficient. The sensor is associated with a signal processing stage containing one or more transistors arranged in parallel with one or more pull-up resistors. An analog-to-digital converter receives a voltage from an intermediate point between the sensor and the pull-up resistors. The transistor is controlled by a square wave voltage, causing it to alternately and regularly switch between an on-state and an off-state. The voltage at an analog input of the converter is measured when the transistor is on and when it is off. A saturation voltage of the transistor is determined from these two measured values.The value of a corrected voltage and the temperature around the sensor are derived from this.

[0007] DE 10 2016 105 506 A1 discloses a temperature measuring device comprising an electrical circuit with a first, temperature-dependent resistor and a second resistor, a microcontroller for determining a temperature based on an input voltage, wherein the input voltage depends at least on the first resistor, and a switching device for switching back and forth between a first and a second switching state, wherein the input voltage in the first switching state also depends on the second resistor, and wherein the input voltage in the second switching state is independent of the second resistor.

[0008] DE 11 2015 005 117 T5 discloses a temperature detection device comprising a thermistor; a resistor connected in series with the thermistor; a temperature detector connected to a first node between the thermistor and the resistor; and a switching circuit comprising a first switch, a second switch, a third switch, and a fourth switch. The first and third switches are connected in series, the second and fourth switches are connected in series, the first and second switches are connected to a supply side, the third and fourth switches are connected to a ground side, the thermistor is connected to a second node between the first switch and the third switch, and the resistor is connected to a third node between the second switch and the fourth switch.

[0009] JP 2008 - 14 774 A discloses a temperature measuring device capable of accurately measuring temperature without being dependent on a supply voltage. A temperature measuring element measures the temperature when a supply voltage is applied. The temperature measuring element outputs a voltage containing information about the temperature and information about the supply voltage. Additionally, the temperature measuring element outputs a voltage containing the information about the supply voltage but without the temperature information. A temperature determination element receives the voltages. The temperature determination element determines a temperature value by subtracting the information about the supply voltage from the voltage.

[0010] US 2014 O 219 316 A1 discloses a temperature sensing device connected to a temperature sensor and comprising two resistors, a transistor, and a microcomputer. The temperature sensor is connected to ground. The resistors are connected in series between the temperature sensor and a power supply line. The transistor is connected to the resistor on the power supply side. The microcomputer converts a sensor voltage characteristic, generated at a junction between the resistor and the temperature sensor, into a first characteristic and a second characteristic by switching the transistor to an on and an off state. The microcomputer calculates a temperature based on the sensor voltage.When the transistor is in the on state, the microcomputer detects a voltage that develops at a low-voltage output terminal of the transistor and calculates the temperature based on the transistor output voltage and the sensor voltage.

[0011] In JP 2014 – 102 218 A, fluctuations in the resistance value of the resistor element integrated into the integrated circuit and connected in series with the temperature sensor element can be corrected, eliminating the need for a reference resistor to correct the resistor element's resistance value. This allows for the use of a temperature sensor where the resistor element is integrated into the circuit and is therefore small in size. However, the resistance value of both the temperature sensor element and the resistor element connected in series with it changes with temperature.A temperature difference can exist between a temperature sensor element and a signal processing circuit containing a resistor element. For example, if the temperature of the temperature sensor element remains constant but the temperature of the signal processing circuit changes, the resistance value of the resistor element will also change. This change in resistance value introduces an error into the voltage signal at the junction between the temperature sensor element and the resistor element. Since the configuration described in JP 2014-102218A cannot correct this error, a problem can arise that prevents highly accurate temperature measurement.

[0012] Additionally, JP 2014 - 102 218 A proposes a method for compensating for temperature changes in the resistive element, in which the resistive element is configured with a combination of a resistor with a negative temperature coefficient and a resistor with a positive temperature coefficient. However, a problem arises in that, with respect to the resistance value of the resistive element in the integrated circuit, fluctuations in the temperature coefficient and resistance value are introduced during the manufacturing process of the signal processing circuit, and the result of the signal processing circuit is not stabilized.Additionally, although it is possible to improve the result by using laser cutting or something similar to adjust the resistance values ​​of individual resistors, there is a problem in that the number of steps in manufacturing increases and manufacturing costs increase. Summary of the invention

[0013] In view of this, it is an objective of the present disclosure to provide a temperature sensor module that achieves highly accurate temperature measurement without increasing the number of manufacturing steps.

[0014] A temperature sensor module according to the present disclosure is a temperature sensor module comprising: a temperature sensor element whose resistance changes according to the temperature of a target medium; and a signal processing circuit connected to the temperature sensor element and outputting an electrical signal correlated with the resistance of the temperature sensor element. The signal processing circuit comprises: a resistor connected in series with the temperature sensor element, the resistance of which changes according to a command signal transmitted; a temperature detection circuit that detects and outputs a temperature from the signal processing circuit; and a first analog-to-digital conversion circuit that converts an output signal from the temperature detection circuit into a digital signal and outputs the digital signal.a memory that stores a series connection resistor data element about a relationship between a temperature and the resistance value of the series connection resistor; a digital signal processing circuit that uses the series connection resistor data element stored in the memory to calculate a digital command signal, based on the digital signal indicating the temperature of the signal processing circuit, to maintain the resistance value of the series connection resistor at a constant value, and outputs the digital command signal; and a digital-to-analog conversion circuit that converts the digital command signal into an analog command signal and outputs the analog command signal to the series connection resistor.

[0015] With the temperature sensor module according to the present disclosure, since the resistance value of the resistive element is kept at a constant value in the signal processing circuit, no error due to the resistance value of the resistive element in a voltage signal at a connection point between the temperature sensor element and the resistive element is included, thus enabling highly accurate temperature measurement. Additionally, since the resistance value of the resistive element is kept at a constant value within the signal processing circuit, the result of the signal processing circuit can be stabilized. Furthermore, the processing required to maintain the resistance value of the resistive element at a constant value in the signal processing circuit does not increase the number of steps, thereby reducing manufacturing costs. Brief description of the characters Fig. Figure 1 is a schematic diagram of a temperature sensor module according to a first embodiment; Fig. 2 is a diagram showing a change in an output voltage V A indicates when there is a temperature difference between a temperature sensor element and a series connection resistor, where a platinum resistor is used as the temperature sensor element; Fig. 3 is a diagram showing a change in the output voltage V A indicates when there is a temperature difference between the temperature sensor element and the series connection resistance, where an NTC thermistor is used as the temperature sensor element; Fig. Figure 4 is a diagram showing an example of the configuration of the series connection resistance; Fig. Figure 5 is a schematic configuration of a temperature sensor module according to a second embodiment; Fig. Figure 6 is a schematic configuration diagram of a temperature sensor module according to a third embodiment; and Fig. Figure 7 is a configuration diagram that shows an example of the temperature sensor module hardware. Detailed description of the preferred embodiments of the invention

[0016] A temperature sensor module according to an embodiment of the present disclosure is described below with reference to the figures. In the figures, identical or related elements and parts are designated by the same reference numerals in the description. First embodiment

[0017] Fig. Figure 1 is a schematic configuration diagram of a temperature sensor module 100 according to a first embodiment. The temperature sensor module 100 is a module for detecting the temperature of a target medium and outputs an electrical signal corresponding to the temperature of the target medium. The temperature sensor module 100 comprises a temperature sensor element 1 and a signal processing circuit 2. Here, a resistance thermometer, in which the resistance value changes according to the temperature of the target medium, is used as the temperature sensor element 1.A method for detecting temperature using the temperature sensor element 1 according to the present disclosure is a method in which the temperature sensor element 1 and a series connection resistor 3, which is included in the signal processing circuit 2, are connected in series, a predetermined supply voltage is applied to both ends of the temperature sensor element 1 and the series connection resistor 3, and an output voltage corresponding to a change in temperature is obtained from a connection point 9 between the temperature sensor element 1 and the series connection resistor 3, thereby detecting a temperature.

[0018] The temperature sensor element 1 is, for example, a platinum resistor or an NTC thermistor. The signal processing circuit 2 is connected to the temperature sensor element 1 and outputs an electrical signal correlated to the resistance value of the temperature sensor element 1. The signal processing circuit 2 is an integrated circuit obtained through integration via a semiconductor process. The signal processing circuit 2 includes the series connection resistor 3, which is connected in series with the temperature sensor element 1, and whose resistance value changes according to a command signal that is transmitted. The series connection resistor 3 is a thick film resistor, a diffuse resistor, or something similar formed within the integrated circuit.

[0019] For the supply voltage, which is applied to both ends of the series-connected temperature sensor element 1 and the series connection resistor 3, either end can be at a high potential. Fig. Terminal 1 is the high-potential end of series connection resistor 3, and the end of temperature sensor element 1 is grounded. However, the end of temperature sensor element 1 can be high-potential, and the end of series connection resistor 3 can be grounded. A signal of the output voltage obtained from connection point 9 passes through an amplifier or buffer circuit (neither is shown) included in signal processing circuit 2 to be output externally by signal processing circuit 2 as a temperature sensor signal 20, which is an analog signal. Alternatively, the output voltage signal can be routed through an analog-to-digital conversion circuit to be output externally by signal processing circuit 2 as a temperature sensor signal 20, which is a digital signal.Additionally, the analog-to-digital conversion circuit and a circuit that applies a supply voltage to both ends of the temperature sensor element 1 and the series connection resistor 3 can be provided outside the signal processing circuit 2. However, if these circuits are integrated with the signal processing circuit 2, the size of the temperature sensor module 100 can be made small.

[0020] The resistance value of temperature sensor element 1 is given as R A defined when the temperature of the temperature sensor element 1 T A The resistance value of the series connection resistor 3 is defined as Rp, and the supply voltage applied to the temperature sensor element 1 and the series connection resistor 3 is defined as V0. If the end of the series connection resistor 3 is connected to the high-potential side for the supply voltage, an output voltage V is generated. Aat connection point 9 represented by equation (1) Equation 1 VA=RPRA+RP×V0

[0021] Similarly, if the end of the temperature sensor element 1 is connected to the high-potential side for the supply voltage, the voltage V will be A at connection point 9 is represented by equation (2). Equation 2 VA=RPRA+RP×V0

[0022] The resistance value of the series connection resistor 3, which is formed by a thick-film resistor, a diffuse resistor, or something similar, also changes according to the temperature. With regard to the temperature sensor element 1 and the series connection resistor 3, if the temperature sensor element 1 and the series connection resistor 3 are located close to each other, there may be cases in which a temperature difference is generated between the temperature sensor element 1 and the series connection resistor 3.The cases in which the temperature difference is generated include: a case in which a temperature difference is generated due to self-heating caused by the operation of the circuits integrated in the signal processing circuit 2; a case in which a temperature difference is generated between the temperature sensor element 1 and the series connection resistor 3 due to thermal resistance between the temperature sensor element 1 and the signal processing circuit 2; and similar cases. If a structure in which only the temperature sensor element 1 is exposed to the target medium is used to improve the accuracy of a detected temperature or to enhance responsiveness, there may also be a case in which a temperature difference is generated between the temperature sensor element 1 and the signal processing circuit 2.Regarding the case where a temperature difference is generated between the temperature sensor element and the series connection resistor 3, for example, if the temperature of the temperature sensor element 1 has not changed but the temperature of the series connection resistor 3 has changed, only the resistance value of the series connection resistor 3 changes. As a result, an error due to the change in the resistance value of the series connection resistor 3 is present in the output voltage V. A at the connection point 9 between the temperature sensor element 1 and the series connection resistor 3, and the output voltage V A It changes.

[0023] Fig. 2 and Fig. 3 each give an example of the way in which the output voltage V A changes when a temperature Tp and the temperature T Aof the temperature sensor element 1 differ from each other, where Tp is the temperature of the series connection resistor 3. Fig. 2 is a diagram showing a change in the output voltage V A indicates when there is a difference in temperature between the temperature sensor element 1 and the series connection resistor 3, where a platinum resistor is used as the temperature sensor element 1. Fig. Figure 3 is a diagram showing this change, using an NTC thermistor as the temperature sensor element 1. If there is a difference between the temperature T A and the temperature Tp is generated, the output voltage V changes. A as follows. If the temperature sensor element 1 is a resistance thermometer, such as a platinum resistor, where the resistance value changes essentially linearly with the temperature, the output voltage V changes. A , as in Fig. Figure 2 shows. However, if the temperature sensor element 1 is a resistance thermometer such as an NTC thermistor, where the resistance value changes non-linearly with the temperature, the output voltage V changes. A , as in Fig. Figure 3 shows that, therefore, in order to achieve a highly accurate temperature measurement, the resistance value of the series connection resistor 3 must be kept at a constant value, regardless of the temperature, thus preventing any change in the output voltage V. A is prevented due to a change in the resistance value of the series connection resistor 3. <schaltkreiskonfiguration>

[0024] The internal circuit configuration of the signal processing circuit 2, which is a major part of this disclosure and maintains the resistance value of the series connection resistor 3 at a constant value, is described. As in Fig. As shown in Figure 1, the signal processing circuit 2 comprises a temperature detection circuit 4, a first analog-to-digital conversion circuit 5, a digital signal processing circuit 6, a memory 7, and a digital-to-analog conversion circuit 8. The temperature detection circuit 4 detects a temperature of the signal processing circuit 2 and outputs the temperature to the first analog-to-digital conversion circuit 5. If the signal processing circuit 2 is a silicon integrated circuit, a silicon diode is provided as a semiconductor temperature sensor in the temperature detection circuit 4. The first analog-to-digital conversion circuit 5 converts the output signal from the temperature detection circuit 4 into a digital signal and outputs the digital signal to the digital signal processing circuit 6.

[0025] Memory 7 stores a series connection resistance data element about the relationship between temperature and the resistance value of series connection resistor 3. The series connection resistance data element specifies a reference temperature, a reference resistance value of series connection resistor 3 (which is the resistance value of series connection resistor 3 at the reference temperature), and a slope of any change in the resistance value of series connection resistor 3 relative to the temperature of series connection resistor 3. Digital signal processing circuit 6 uses the series connection resistance data element stored in memory 7 to calculate a resistance value of series connection resistor 3 based on the digital signal that specifies the temperature of signal processing circuit 2.The digital signal processing circuit 6 calculates a digital command signal based on the calculated resistance value to maintain the resistance value of the series connection resistor 3 at a predetermined constant value and outputs the digital command signal. The digital-to-analog conversion circuit 8 converts the digital command signal into an analog command signal and outputs the analog command signal to the series connection resistor 3. The resistance value of the series connection resistor 3 changes according to the transmitted analog command signal, thereby maintaining the resistance value of the series connection resistor 3 at the predetermined constant value.

[0026] In this configuration, the resistance value of the series connection resistor 3 can be kept constant. Therefore, no error due to temperature-dependent changes in the resistance value of the series connection resistor 3 is superimposed on the output voltage obtained from the connection point 9 between the temperature sensor element 1 and the series connection resistor 3, and the output voltage correlates only with the temperature of the temperature sensor element 1. Accordingly, the temperature sensor module 100 can measure the temperature of the target medium with high accuracy. <Digital-Analog-Umwandlungsschaltkreis 8 und Serienverbindungswiderstand 3>

[0027] Configurations of the digital-to-analog conversion circuit 8 and the series connection resistor 3 for maintaining the resistance value of the series connection resistor 3 at a constant value are described. The digital-to-analog conversion circuit 8 and the series connection resistor 3 form, for example, a digital potentiometer included in the signal processing circuit 2. An example of the series connection resistor 3 formed in the digital potentiometer is shown in Fig. Figure 4 shows that the series connection resistor 3 comprises a plurality of resistive elements 3a connected in series and a plurality of switching elements 3b that establish or break a direct connection between the two ends of each plurality of resistive elements 3a. The plurality of switching elements 3b are individually switched on or off by the transmitted command signal. The resistance value of the series connection resistor 3 changes when the switches are turned on or off. Based on the digital command signal from the digital signal processing circuit 6, the on / off control of the switches is implemented to counteract the change in resistance that occurs according to temperature, thus allowing the resistance value of the series connection resistor 3 to be easily maintained at a constant value. The configuration of the series connection resistor 3 is not limited to what is shown in Figure 4. Fig. Figure 4 shows a variable resistor, such as a conductor circuit. The digital-to-analog conversion circuit 8 and the series connection resistor 3 can be configured with a combination of a fixed resistor and a digital potentiometer, or with a combination of multiple digital potentiometers. <Speicher 7>

[0028] Memory 7 uses a non-volatile ROM (read-only memory). If a mask ROM is used as memory 7, the content stored in the mask ROM cannot be overwritten after the mask ROM has been manufactured. Therefore, a series connection resistance data element is stored in memory 7 in a manufacturing process of the signal processing circuit 2, based on a standard average value for the series connection resistances 3. If mask ROMs are used, the series connection resistance data elements belonging to variations of corresponding series connection resistances 3 cannot be stored in memory 7.

[0029] If programmable ROMs are used as memory 7, data elements can be written individually to the programmable ROMs contained in the individual signal processing circuits 2 after the signal processing circuits 2 have been manufactured. After the resistance values ​​of the individual series connection resistors 3 have been measured at a specific temperature, the obtained series connection resistor data elements can be written to memory 7. Therefore, the series connection resistor data elements corresponding to variations in the respective series connection resistors 3 are written to memory 7. One specific method for acquiring data elements is, for example, as follows.The resistance of each series connection resistor 3 is measured when the temperature of the associated signal processing circuit 2 is set to a predetermined temperature T1, and the measured resistance value is defined as R1. Next, the resistance of the series connection resistor 3 is measured when the temperature of the signal processing circuit 2 is set to a temperature T2, which differs from T1, and the measured resistance value is defined as R2. From these measurements, a slope β, representing the change in the resistance of the series connection resistor 3 relative to its temperature, is calculated.The reference temperature T1, the reference resistance value R1 of the series connection resistor 3, and the rate of change in the resistance value of the series connection resistor 3 are written to the associated memory locations 7 as a series connection resistor data element. Accordingly, the memory locations 7 store series connection resistor data elements for the individual series connection resistors 3.

[0030] Even in a state where the temperature sensor element 1 and the signal processing circuits 2 are not connected, the resistance of the series connection resistor 3 can be measured at a specific temperature. Therefore, the resistance of the series connection resistor 3 can be measured in a form factor where the heat capacity is less than that of the temperature sensor module 100, such as a wafer form factor with multiple signal processing circuits 2 or a sub-module form factor where the temperature sensor element 1 has not yet been connected. Since the heat capacity is small, it is possible to reduce the time required to stabilize the temperature of the signal processing circuits 2 at the time of measurement.

[0031] If programmable ROMs are used as memory 7, series connection resistor data elements belonging to fluctuations of corresponding series connection resistors 3 can be stored in memory 7. Therefore, the resistance value of each series connection resistor 3 can be kept constant with high accuracy. Accordingly, the temperature sensor module 100 can measure the temperature of the target medium with higher accuracy.

[0032] A specific application of the temperature sensor module 100 is described. The temperature sensor module 100 is suitable for measuring the temperature of target media such as the intake air and exhaust gas of a motor vehicle engine. The flow rate of the intake air or exhaust gas changes according to the engine's rotational speed. In a motor vehicle engine control unit, the temperature sensor module 100 must exhibit a rapid temperature response capability. Therefore, the temperature sensor module 100 is positioned to protrude into the center of an intake air or exhaust gas flow pipe.Furthermore, to reduce pressure loss of air flowing in the flow tube due to the protruding temperature sensor module 100, the signal processing circuit 2 is arranged on the outer side of the flow tube to be separated from the temperature sensor element 1, thus minimizing the volume of the temperature sensor module 100 protruding into the flow tube. Additionally, to ensure that the temperature of the temperature sensor element 1 approaches the temperature of the exhaust gas inlet air, a connecting section between the temperature sensor element 1 and the signal processing circuit 2 has a thin and elongated structure, such that heat conduction from the temperature sensor element 1 to the signal processing circuit 2 is minimized.Therefore, the temperature sensor element 1 and the signal processing circuit 2 are thermally isolated from each other, and the temperature of the temperature sensor element 1 and the temperature of the signal processing circuit 2 do not coincide depending on the operating state of the vehicle. Even if the temperature of the temperature sensor element 1 and the temperature of the signal processing circuit 2 do not coincide, the configuration described above allows the resistance value of the series connection resistor 3 to be maintained at a constant value. Accordingly, the temperature sensor module 100 can measure the temperature of the target medium with high accuracy. The configuration of this disclosure is effective in such applications.

[0033] As described above, in the first embodiment of the temperature sensor module 100, the resistance value of the series connection resistor 3 is maintained at a constant value within the signal processing circuit 2, and the output voltage obtained from the connection point 9 between the temperature sensor element 1 and the series connection resistor 3 correlates only with the temperature of the temperature sensor element 1. Accordingly, the temperature sensor element 100 can measure the temperature of the target medium with high accuracy. Furthermore, since the series connection resistor 3 and the circuitry for maintaining the resistance value of the series connection resistor 3 at a constant value are integrated with the signal processing circuit 2, the size of the temperature sensor module 100 can be made small.Additionally, since the series connection resistor 3 comprises the multitude of resistive elements connected in series and the multitude of switching elements that establish or break a direct connection between the two ends of each of these resistive elements, the resistance value of the series connection resistor 3 can easily be kept at a constant value. Furthermore, if programmable ROMs are used as memory 7, individual series connection resistor data elements belonging to fluctuations of corresponding series connection resistors 3 can be stored in the programmable ROMs. Thus, the resistance value of each series connection resistor 3 can be kept at a constant value with high accuracy. Accordingly, the temperature sensor module 100 can measure the temperature of the target medium with higher accuracy.Additionally, since the resistance value of the series connection resistor 3 is kept constant within the signal processing circuit 2, the output of the signal processing circuit 2 can be stabilized. Furthermore, maintaining the resistance value of the series connection resistor 3 at a constant value within the signal processing circuit 2 does not increase the number of manufacturing steps for the temperature sensor module 100, thus reducing manufacturing costs. Second embodiment

[0034] A temperature sensor module 100 according to a second embodiment is described. Fig. Figure 5 is a schematic configuration diagram of the temperature sensor module 100 according to the second embodiment. In the temperature sensor module 100 according to the second embodiment, the signal processing circuit 2 comprises a second analog-to-digital conversion circuit 10.

[0035] The signal processing circuit 2 comprises the second analog-to-digital conversion circuit 10 in addition to the components described in the first embodiment. The second analog-to-digital conversion circuit 10 converts a voltage signal at the junction 9 between the temperature sensor element 1 and the series connection resistor 3 into a digital voltage signal and outputs the digital voltage signal to the digital signal processing circuit 6. The memory 7 stores a temperature sensor element data element about the relationship between the resistance value of the temperature sensor element 1 and the temperature of the temperature sensor element 1.The temperature sensor element data element specifies a reference temperature, a reference resistance value (which is the resistance value of temperature sensor element 1 at the reference temperature), and the rate of change in the resistance value of temperature sensor element 1 relative to the temperature of temperature sensor element 1. The digital signal processing circuit 6 uses the temperature sensor element data element, which is stored in memory 7, to calculate the temperature of temperature sensor element 1 based on the digital voltage signal and outputs a temperature sensor signal 20 as an electrical signal. The output electrical signal can be further output as an analog signal via a digital-to-analog conversion circuit (not shown).Alternatively, the output electrical signal can be output as a digital signal via a digital signal interface circuit of a PWM (pulse width modulation) type, a SENT (single-edge nibble transmission) type, or something similar. <platin-widerstand>

[0036] A case where the temperature sensor element 1 is a platinum resistor is described. Memory 7 stores, as the temperature sensor element data element, a reference temperature, a reference resistance value (which is the resistance value of the platinum resistor at the reference temperature), and the rate of change of the resistance value of the platinum resistor relative to the temperature of the platinum resistor. Here, if the reference temperature is defined as T0, the reference resistance value is defined as R0, the rate of change is defined as α, the resistance value of the series connection resistor 3 is defined as Rp, the supply voltage applied to the series connection resistor 3 and the platinum resistor is defined as V0, and the voltage at the junction 9 between the series connection resistor 3 and the platinum resistor is defined as V. A defined and is the resistance value of the platinum resistor at a specific temperature T A as R A The resistance value R is defined A represented by equation (3). Equation 3 RA=α×(TA−T0)+R0

[0037] If the end of the series connection resistor 3 is connected to the high-potential side for the supply voltage, the voltage V will be A represented by equation (4). Equation 4 VA=RP{α×(TA−T0)+R0}+RP×V0

[0038] From equation (4) the specific temperature T is obtained A , which is detected by the platinum resistor, is represented by equation (5). Equation 5 TA=T0+1α×(V0−VAVA×RP−R0)

[0039] Similarly, if the end of the platinum resistor is connected to the high-potential side for the supply voltage, the voltage V will be A represented by equation (6). Equation 6 VA=α×(TA−T0)+R0{α×(TA−T0)+R0}+RP×V0

[0040] From equation (6) the specific temperature T is obtained A detected by the platinum resistance using equation (7). Equation 7 TA=T0+1α×(VAV0−VA×RP−R0)

[0041] Using equation (5) or equation (7), the temperature of the platinum resistor in the digital signal processing circuit 6 is calculated on the basis of: the reference temperature T0, the reference resistance value R0 and the gain α stored in memory 7; the preset resistance value Rp of the series connection resistor, the preset supply voltage V0; and the voltage V A , which is a digital voltage signal.

[0042] Although the case where the temperature sensor element 1 is a platinum resistor has been described, the metal used as the temperature sensor element 1 is not limited to platinum, and the temperature sensor element 1 can be a resistance thermometer made of another metal such as nickel or copper. Regarding a property of the change in resistance relative to temperature of the resistor made of a metal such as nickel or copper, the change exhibits high non-linearity compared to the case of the platinum resistor. Therefore, it is preferred that the non-linearity be corrected to increase the accuracy of converting a resistance value into temperature information. In the platinum resistor example, the reference temperature T0, the reference resistance value R0, and the slope α are each used across the entire voltage range V. A stored in memory 7. In this case of a resistance thermometer with high non-linearity, the voltage range V is A divided into several segments, with the values ​​of the reference temperature T0, the reference resistance value R0 and the slope α in each segment stored in memory 7, and the temperature of the resistance is calculated for each segment, thereby correcting the non-linearity.

[0043] In this configuration, the reference temperature of the resistance thermometer, which is used as temperature sensor element 1, the reference resistance value (the resistance value of the resistance thermometer at the reference temperature), and the rate of change of the resistance value of the resistance thermometer relative to the temperature of the resistance thermometer are stored in memory 7 as the temperature sensor element data element. Thus, the temperature of the resistance thermometer can be calculated using the temperature sensor element data element. Therefore, even when resistance thermometers with different characteristics are used, the temperature sensor module 100 can measure the temperature of the target medium with high accuracy.Additionally, if a platinum resistor, which is a resistance thermometer with low non-linearity, is used as the temperature sensor element 1, a value of the reference temperature T0, the reference resistance value R0 and the slope α in the entire voltage range at the junction 9 is stored in the memory 7, and thus the capacity of the memory 7 can be reduced. <NTC Thermistor>

[0044] A case where the temperature sensor element 1 is an NTC thermistor is described. The NTC thermistor has the property that its resistance changes logarithmically with temperature. Memory 7 stores, as the temperature sensor element data element, a reference temperature, a reference resistance value (which is the resistance value of the NTC thermistor at the reference temperature), and the rate of change of the NTC thermistor's resistance value relative to its temperature.Here, if the reference temperature is defined as T0, the reference resistance value is defined as R0, the slope is defined as B, the resistance value of the series connection resistor 3 is defined as Rp, the supply voltage applied to the series connection resistor 3 and the NTC thermistor is defined as V0, the voltage at the connection point 9 between the series connection resistor 3 and the NTC thermistor is defined as VB, and if the resistance value of the NTC thermistor at the specified temperature TB is defined as Rp, the resistance value is R. B represented by equation (8). Equation 8 RB=R0×exp{B×(1TB−1T0)}

[0045] The end of the series connection resistor 3 is connected to the high-potential side for the supply voltage, resulting in the voltage V B represented by equation (9). Equation 9 VB=RPR0×exp{B×(1TB−1T0)}+RP×V0

[0046] From equation (9) the specific temperature T is obtained B represented by the NTC thermistor using equation (10). Equation 10 TB=1 / {1B×ln(RPR0×V0−VBVB)+1T0}

[0047] Similarly, if the end of the NTC thermistor is connected to the high-potential side for the supply voltage, the voltage V will be B represented by equation (11). Equation 11 VB=R0×exp{B×(1TB−1T0)}R0×exp{B×(1TB−1T0)}+RP×V0

[0048] From equation (11) the specific temperature T is obtained B represented by the NTC thermistor using equation (12). Equation 12 TB=1 / {1B×ln(RPR0×VBV0−VB)+1T0}

[0049] Using equation (10) or equation (12), the temperature of the NTC thermistor in the digital signal processing circuit 6 is calculated on the basis of: the reference temperature T0, the reference resistance value R0 and the slope B, which are stored in memory 7; the preset resistance value Rp of the series connection resistor; the preset supply voltage V0; and the voltage V B , which is a digital voltage signal.

[0050] In this configuration, the reference temperature of the NTC thermistor, which is used as temperature sensor element 1, the reference resistance value (the resistance of the NTC thermistor at the reference temperature), and the rate of change of the resistance value of the NTC thermistor relative to the temperature of the NTC thermistor are stored in memory 7 as the temperature sensor element data element. Thus, the temperature of the NTC thermistor can be calculated using the temperature sensor element data element. Therefore, the temperature sensor module 100 can measure the temperature of the target medium with high accuracy. Additionally, if the NTC thermistor is used as temperature sensor element 1, a value each for the reference temperature T0, the reference resistance value R0, and the rate of change B across the entire voltage range at junction 9 is stored in memory 7, thus reducing the capacity of memory 7. <Speicher 7>

[0051] If a mask ROM is used as memory 7, the content stored in the mask ROM cannot be overwritten. Therefore, in the manufacturing process of the signal processing circuit 2, if a temperature sensor element 1 is to be connected, a temperature sensor element data element is predetermined to be stored in memory 7, containing standard mean values ​​for a slope and a reference resistance value of the temperature sensor element 1 to be connected. If mask ROMs are used, temperature sensor element data elements belonging to fluctuations of corresponding temperature sensor elements 1 cannot be stored in memory 7.

[0052] Field-programmable ROMs are used as memory 7. Data elements can be individually written into the programmable ROMs, which are contained in individual signal processing circuits 2, after the signal processing circuits 2 have been manufactured. After the resistance values ​​of the individual temperature sensor elements 1 have been measured at a specific temperature, the resulting temperature sensor element data elements can be written into the memory. Therefore, the temperature sensor element data elements corresponding to the fluctuations of the respective temperature sensor elements 1 are written into memory 7. Additionally, since each temperature sensor element data element can be modified, a temperature sensor element 1 with a different property can also be connected to the signal processing circuit 2.Additionally, in the form of the temperature sensor module 100, in which the temperature sensor element 1 and the signal processing circuit 2 are connected, the reference resistance value of the temperature sensor element 1 and the value of the slope can be calculated from data obtained beforehand by measuring a voltage signal at the connection point 9 between the temperature sensor element 1 and the series connection resistor 3, when the temperature of the temperature sensor module 100 is kept at a predetermined temperature, thereby obtaining a temperature sensor element data element and storing the calculated temperature sensor element data element in the memory 7.

[0053] If the programmable ROMs are used as memory locations 7, the temperature sensor element data elements belonging to fluctuations of the corresponding temperature sensor elements 1 can be stored in memory locations 7. Accordingly, the temperature sensor module 100 can measure the temperature of a target medium with higher accuracy.

[0054] Additionally, the same circuit as the digital signal processing circuit 6 for calculating the resistance value of the series connection resistor 3, as described in the first embodiment, can be used as the digital signal processing circuit 6 for calculating the temperature of the temperature sensor element 1 using the temperature sensor element data element. Since the calculation of the temperature of the temperature sensor element 1 and the calculation of the resistance value of the series connection resistor 3 are performed in the same circuit, the size of the signal processing circuit 2 can be prevented from increasing.

[0055] As described above, in the temperature sensor module 100 according to the second embodiment, the reference temperature of the temperature sensor element 1, the reference resistance value (the resistance value of the temperature sensor element 1 at the reference temperature), and the rate of change in the resistance value of the temperature sensor element 1 relative to the temperature of the temperature sensor element 1 are stored in memory 7 as the temperature sensor element data element. The temperature of the temperature sensor element 1 can then be calculated using this data element. Thus, even if temperature sensor elements 1 with different properties are used, the temperature sensor module 100 can measure the temperature of the target medium with high accuracy.Additionally, if programmable ROMs are used as memory 7, temperature sensor element data elements from individual temperature sensor elements 1, which correspond to fluctuations of the respective temperature sensor elements 1, can be stored in memory 7. Accordingly, the temperature sensor element 100 can measure the temperature of the target medium with higher accuracy. Furthermore, if a platinum resistor is used as the temperature sensor element 1, a change in the resistance relative to the temperature of the platinum resistor exhibits some non-linearity, and a value of each of the reference temperature T0, the reference resistance value R0, and the slope α across the entire voltage range at junction 9 is stored in memory 7, thus reducing the capacity of memory 7.Additionally, if an NTC thermistor is used as the temperature sensor element 1, a value of the reference high toe zero, the reference resistance value R0, and the slope B across the entire voltage range at junction 9 is stored in memory 7, thus reducing the capacity of memory 7. Furthermore, since the temperature of the temperature sensor element 1 and the resistance value of the series connection resistor 3 can be calculated in the same circuit, the size of the signal processing circuit 2 can be kept smaller. Third embodiment

[0056] A temperature sensor module 100 according to a third embodiment is described. Fig. Figure 6 is a schematic configuration diagram of the temperature sensor module 100 according to the third embodiment. The temperature sensor module 100 according to the third embodiment comprises a physical quantity sensor 11, and the signal processing circuit 2 of the temperature sensor module 100 comprises a third analog-to-digital conversion circuit 12.

[0057] In addition to the components described in the second embodiment, the temperature sensor module 100 includes the physical quantity sensor 11 for detecting a specific physical quantity. The type of physical quantity to be detected by the physical quantity sensor 11 is not particularly limited. The type of physical quantity is light, pressure, flow rate, magnetism, or something similar, and any of these can be used as long as a detected physical quantity can be output as an electrical signal. Furthermore, the number of physical quantity sensors 11 is not limited to one and can be two or more. Additionally, the physical quantity sensor 11 can be integrated with the signal processing circuitry 2.

[0058] The signal processing circuit 2 comprises the third analog-to-digital conversion circuit 12 in addition to the components described in the second embodiment. The third analog-to-digital conversion circuit 12 converts an output signal from the physical quantity sensor 11 into a digital physical quantity signal and outputs the digital physical quantity signal to the digital signal processing circuit 6. The memory 7 stores a physical quantity sensor temperature data element about the relationship between the temperature and the output value of the physical quantity sensor 11. The physical quantity sensor temperature data element specifies a reference temperature, a reference output value (which is an output value of the physical quantity sensor at the reference temperature), and a slope of any change in the output value of the physical quantity sensor relative to the temperature of the physical quantity sensor.The digital signal processing circuit 6 uses the physical quantity sensor temperature data element stored in memory 7 to calculate the digital physical quantity signal based on the digital signal indicating the temperature of the signal processing circuit 2, and outputs the corrected digital physical quantity signal as a physical quantity sensor signal 21.

[0059] If programmable ROMs are used as memory 7, data elements can be individually written into the programmable ROMs that are contained in the individual signal processing circuits 2 after the signal processing circuits 2 have been manufactured. After the output values ​​of the individual physical quantity sensors 11 have been measured at a specific temperature, the obtained physical quantity sensor temperature data elements can be written to the memories. Therefore, physical quantity sensor temperature data elements that correspond to fluctuations of the respective physical quantity sensors 11 are written to the memories 7. Additionally, since each physical quantity sensor temperature data element can be changed, a physical quantity sensor 11 with a different property can also be connected to the signal processing circuit 2.Additionally, a physical quantity sensor 11 can also be connected to detect another physical quantity instead of the signal processing circuit 2.

[0060] When the digital signal processing circuit 6 is used to correct the output of the physical quantity sensor 11 using the physical quantity sensor temperature data element, the same circuit as the digital signal processing circuit 6 can be used to calculate the resistance value of the series connection resistor 3, as described in the first embodiment. Since both the calculation to correct the output of the physical quantity sensor 11 and the calculation of the resistance value of the series connection resistor 3 are performed in the same circuit, the size of the signal processing circuit 2 can be prevented from increasing.

[0061] If the physical quantity sensor 11 is located close to the signal processing circuit 2, there is no significant temperature difference between the physical quantity sensor 11 and the signal processing circuit 2. Therefore, if the output of the physical quantity sensor 11 is also corrected using information from the temperature detection circuit 4 of the signal processing circuit 2, temperature compensation can be performed for high-accuracy physical quantity detection. Additionally, if the physical quantity sensor 11 is integrated with the signal processing unit 2, there is no temperature difference between the physical quantity sensor 11 and the signal processing unit 2. Therefore, temperature compensation can be performed for even higher-accuracy physical quantity detection.

[0062] As described above, in the third embodiment of the temperature sensor module 100, the physical quantity sensor temperature data element is stored in memory 7 via the physical quantity sensor 11, and a calculation to correct the output of the physical quantity sensor 11 can be performed using the physical quantity sensor temperature data element. Thus, even if physical quantity sensors 11 with different properties are used, the temperature sensor module 100 can measure the physical quantity detected by the physical quantity sensor 11 with high accuracy. Additionally, if programmable ROMs are used as memory 7, physical quantity sensor temperature data elements from individual physical quantity sensors 11, which correspond to fluctuations of the respective physical quantity sensors 11, can be stored in memory 7.Accordingly, the temperature sensor module 100 can measure the physical quantity detected by the physical quantity sensor 11 with higher accuracy. Furthermore, since a calculation to correct the output of the physical quantity sensor 11 and a calculation of the resistance value of the series connection resistor 3 can be performed in the same circuit, the size of the signal processing circuit 2 can be prevented from increasing. Additionally, the temperature sensor module 100 can include the physical quantity sensor 11 without increasing the size of the signal processing circuit 2.

[0063] As in Fig. As shown in Figure 7, a device of the temperature sensor module 100, for example, consists of a processor 110 and a storage device 111. Although not shown, the storage device 111 comprises a volatile storage device, such as main memory, and a non-volatile auxiliary storage device, such as flash memory. Alternatively, the storage device 111 can include a hard disk as the auxiliary storage device instead of flash memory. The processor 110 executes a program given by the storage device 111. In this case, the program is input into the processor 110 from the auxiliary storage device via the volatile storage device. Additionally, the processor 110 can output data, such as a calculation result, to the volatile storage device of the storage device 111 or store candidates in the auxiliary storage device via the volatile storage device.

[0064] Although the disclosure above is described in relation to various exemplary embodiments, it should be understood that various features, aspects and functionalities described in one or more of the individual embodiments are not limited in their applicability to the specific embodiment with which they are described, but instead can be applied alone or in various combinations to one or more of the embodiments of the disclosure.

[0065] It is therefore understood that numerous modifications, not listed as examples, can be devised without deviating from the scope of protection described in this disclosure. For example, at least one of the feature components can be modified, added, or removed. At least one of the feature components mentioned in at least one of the preferred embodiments can be selected and combined with the feature components described in another preferred embodiment. Description of the reference symbols 1 temperature sensor element 2 Signal processing circuit 3 series connection resistor 3a Resistance element 3b Switching element 4 Temperature detection circuit 5 First analog-to-digital conversion circuit 6 Digital signal processing circuit 7 storage 8 Digital-to-analog conversion circuit 9 connection point 10 Second analog-to-digital conversion circuit 11 Physical Quantity Sensor 12 Third Analog-to-Digital Conversion Circuit 20 Temperature sensor signal 21 Physical quantity sensor signal 100 Temperature sensor module 110 processor 111 Storage device < / schaltkreiskonfiguration>

Claims

[1] A temperature sensor module (100), comprising: a temperature sensor element (1) whose resistance value changes according to the temperature of a target medium; and a signal processing circuit (2) which is connected to the temperature sensor element (1) and which outputs an electrical signal which correlates with the resistance value of the temperature sensor element (1), wherein the signal processing circuit (2) comprises a series connection resistor (3) which is connected in series with the temperature sensor element (1) and whose resistance value changes according to a command signal that has been transmitted, a temperature detection circuit (4) that detects and outputs a temperature of the signal processing circuit (2), a first analog-to-digital conversion circuit (5) that converts an output signal from the temperature detection circuit (4) into a digital signal and outputs the digital signal a memory (7) which stores a series connection resistance data element about a relationship between a temperature and the resistance value of the series connection resistor (3), a digital signal processing circuit (6) which uses the series connection resistor data element stored in the memory (7) to calculate a digital command signal on the basis of the digital signal indicating the temperature of the signal processing circuit (2) in order to maintain the resistance value of the series connection resistor (3) at a constant value, and outputs the digital command signal, and a digital-to-analog conversion circuit (8) that converts the digital command signal into an analog command signal and outputs the analog command signal to the series connection resistor (3). [2] Temperature sensor module (100) according to claim 1, wherein the series connection resistor (3) comprises a plurality of resistive elements (3a) connected in series and a plurality of switching elements (3b) that establishes or disconnects a direct connection between the two terminals of each plurality of resistive elements (3a), and the multitude of switching elements (3b) can be individually switched on or off by the command signal that was transmitted. [3] The temperature sensor module (100) according to claim 1 or 2, wherein the signal processing circuit (2) further comprises a second analog-to-digital conversion circuit (10) which converts a voltage signal at a connection point (9) between the temperature sensor element (1) and the series connection resistor (3) into a digital voltage signal and outputs the digital voltage signal, the memory (7) stores a temperature sensor element data element about a relationship between the resistance value of the temperature sensor element (1) and a temperature of the temperature sensor element (1), and The digital signal processing circuit (6) uses the temperature sensor element data element stored in the memory (7) to calculate a temperature of the temperature sensor element (1) based on the digital voltage signal and outputs the temperature as the electrical signal. [4] Temperature sensor module (100) according to claim 3, wherein the temperature sensor element (1) is a platinum resistor, and The memory (7) as the temperature sensor element data element stores a reference temperature, a reference resistance value which is a resistance value of the platinum resistor at the reference temperature, and a slope of a change in a resistance value of the platinum resistor relative to a temperature of the platinum resistor. [5] Temperature sensor module (100) according to claim 4, wherein the digital signal processing circuit (6) a temperature T A of the temperature sensor element (1) is calculated using the following equation: TA=T0+1 / α×{VA / (V0−VA)×RP−R0}, where where T0 represents the reference temperature, R0 represents the reference resistance value, α represents the slope, Rp represents the resistance value of the series connection resistor (3), V0 represents a supply voltage that is applied to the series connection resistor (3) and the temperature sensor element (1), and V A represents the digital voltage signal at the connection point (9). [6] Temperature sensor module (100) according to claim 3, wherein the temperature sensor element (1) is an NTC thermistor, and The memory (7) as the temperature sensor element data element stores a reference temperature, a reference resistance value which is a resistance value of the NTC thermistor at the reference temperature, and a slope of a change in a resistance value of the NTC thermistor relative to a temperature of the NTC thermistor. [7] Temperature sensor module (100) according to claim 6, wherein the digital signal processing circuit (6) a temperature T B of the temperature sensor element (1) is calculated using the following equation: TB=1 / [1 / B×ln{RP / R0×(V0−VB) / VB}+1 / T0], where T0 represents the reference temperature, R0 represents the reference resistance value, B represents the slope, Rp represents the resistance value of the series connection resistor (3), V0 represents a supply voltage that is applied to the series connection resistor (3) and the temperature sensor element (1), and V B represents the digital voltage signal at the connection point (9). [8] Temperature sensor module (100) according to any one of claims 1 to 7, wherein the temperature sensor module (100) further comprises a physical quantity sensor (11) that detects a specific physical quantity, wherein the signal processing circuit (2) comprises a third analog-to-digital conversion circuit (12) that converts an output signal from the physical quantity sensor (11) into a digital physical quantity signal and outputs the digital physical quantity signal, the memory (7) stores a physical quantity sensor temperature data element about a relationship between a temperature and an output value of the physical quantity sensor (11), and The digital signal processing circuit (6) uses the physical quantity sensor temperature data element stored in the memory (7) to correct the digital physical quantity signal based on the digital signal indicating the temperature of the signal processing circuit (2) and outputs the corrected digital physical quantity signal. [9] Temperature sensor module (100) according to any one of claims 1 to 8, wherein the memory (7) is a programmable ROM.

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