JP6409323B2 - CIRCUIT DEVICE, TEMPERATURE DETECTING DEVICE, ELECTRONIC DEVICE, TEMPERATURE DETECTING METHOD, AND TEMPERATURE DETECTING METHOD - Google Patents

Description

  The present invention relates to a circuit device, a temperature detection device, an electronic device, a temperature detection method, a method for manufacturing the temperature detection device, and the like.

  Conventionally, a temperature detection device using a thermopile is known as a device that performs temperature detection without contact. This temperature detection device has a thermopile (infrared sensor) that detects infrared radiation of a target object, and a thermistor (temperature sensor) that is provided in the vicinity of the thermopile and detects self temperature (ambient temperature). The thermopile has a property of generating an electromotive force (electromotive voltage) due to a temperature difference between the object temperature and the self temperature. Therefore, the object temperature can be detected based on the detection voltage detected using the thermopile and the detection voltage detected using the thermistor.

JP 2002-48648 A

  In the temperature detection apparatus as described above, for example, adjustment is made so that the temperature of the black body can be measured in an inspection environment in a manufacturing process or the like. However, since the object is not always a black body in an actual use environment, there is a problem that the actual temperature of the object is different from the temperature measured by the temperature detection device for the object. Since the assumed object varies depending on the application, the measurement error also varies depending on the application.

  As a method for inputting a correction value for a measurement error, for example, in Patent Document 1, an infrared ray corresponding to a correction value is output from a correction device, and the infrared ray is received by a thermopile of a temperature detection device, so that the correction value is non-contacted. Is input to a temperature detection device. However, the correction value in this method is for correcting manufacturing variations (individual differences between devices), and does not correct the error between the measured value adjusted in the inspection environment and the measured value in the actual use environment. .

  According to some aspects of the present invention, a circuit device, a temperature detection device, an electronic device, a temperature detection method, and a temperature detection device that can correct an error between a measurement value adjusted in an inspection environment and a measurement value in an actual use environment. Manufacturing methods and the like can be provided.

  One embodiment of the present invention performs A / D conversion on the first detection voltage detected using the infrared sensor, outputs the first detection value of the digital value, and detects the second detected using the temperature sensor. A detection circuit that performs A / D conversion on the detection voltage and outputs a second detection value of a digital value; a control unit that calculates an object temperature based on the first detection value and the second detection value; A storage unit that stores a correlation correction value that represents a difference between the temperature of the target object in an actual use environment and the target object temperature that the control unit calculates for the target object, and the control unit includes the correlation The present invention relates to a circuit device that performs a correlation correction process for correcting the object temperature based on a correction value.

  According to one aspect of the present invention, by correcting the object temperature based on the correlation correction value stored in the storage unit, the temperature in the actual use environment of the object and the object detected for the object The difference with temperature can be corrected. Thereby, it is possible to correct an error between the measured value adjusted in the inspection environment and the measured value in the actual use environment.

  In one aspect of the present invention, the storage unit stores the correlation correction value at each object temperature point of a plurality of object temperature points having different object temperatures, and the control unit stores each object The correlation correction process may be performed based on at least one correlation correction value at a temperature point.

  The error of the measured value in the actual use environment differs depending on the object temperature. In this regard, according to one aspect of the present invention, since the correlation correction can be performed by using at least one correlation correction value at a plurality of object temperature points, it is possible to perform highly accurate correlation correction over a wide temperature range.

  In one aspect of the present invention, the storage unit stores the correlation correction value at each self temperature point of a plurality of self temperature points having different self temperatures for each object temperature point, and the control unit includes: The self-temperature may be obtained based on the second detection value, and the correlation correction process may be performed based on the self-temperature and at least one correlation correction value at each self-temperature.

  The error between the measured value adjusted in the inspection environment and the measured value in the actual use environment depends on the self-temperature of the infrared sensor, and the self-temperature varies depending on the environment and application. In this regard, according to one aspect of the present invention, since the correlation correction can be performed by using at least one correlation correction value at a plurality of self-temperature points, it is possible to perform highly accurate temperature measurement that does not depend on the self-temperature.

  In one aspect of the present invention, the control unit obtains a correction value corresponding to the object temperature by interpolation processing of the correlation correction value, and the object temperature based on the correction value obtained by the interpolation process. The correlation correction process may be performed.

  In this way, a correlation correction value corresponding to the measured object temperature and the self temperature can be obtained from the plurality of correlation correction values at the plurality of object temperature points and the plurality of self temperature points. As a result, the correlation correction can be performed with higher accuracy.

  In the aspect of the invention, the storage unit may store temperature interval information of the plurality of object temperature points.

  In the aspect of the invention, the storage unit may store start temperature information of the plurality of object temperature points.

  According to these one aspect | modes of this invention, the temperature range which sets a target object temperature point can be variably set. Although the temperature range to be measured varies depending on the application, the temperature range can be variably set, so that the correlation correction can be performed in the temperature range to be used.

  In the aspect of the invention, the storage unit may store setting information for variably setting a temperature range that can be set as the correlation correction value and a temperature increment per 1 LSB of the correlation correction value.

  The range of error between the measured value adjusted in the inspection environment and the measured value in the actual use environment depends on the object in the actual use environment. In this regard, in one embodiment of the present invention, the temperature range that can be set as the correlation correction value is variable, so that the range of the correlation correction value according to the error range can be set. Further, since the temperature increment per 1 LSB can be set, the correlation correction value can be performed with the necessary correction accuracy.

  In one aspect of the present invention, the control unit corrects the object temperature based on a correction parameter obtained in an inspection environment, and performs the correlation correction process on the corrected object temperature. Also good.

  In the aspect of the invention, the storage unit may include the correction parameter of at least one correction process of a gain correction process for a temperature characteristic, a correction process for an offset, and a conversion process based on a characteristic coefficient parameter of a thermopile. It may be stored as the correction parameter obtained in the environment.

  In the inspection environment, for example, the manufacturing variation is adjusted using an object that does not depend on the application. For this reason, there is an error in the temperature measured for the object in the actual use environment. According to one aspect of the present invention, such an error can be corrected by the correlation correction process.

  Another aspect of the present invention relates to a temperature detection device including any one of the circuit devices described above, the infrared sensor, and the temperature sensor.

  Another aspect of the invention relates to an electronic device including any one of the circuit devices described above.

  In another aspect of the present invention, A / D conversion is performed on the first detection voltage detected using the infrared sensor, the first detection value of the digital value is output, and the detection is performed using the temperature sensor. A / D conversion is performed on the second detection voltage, a second detection value of a digital value is output, an object temperature is obtained based on the first detection value and the second detection value, and the actual object is detected. A temperature for storing a correlation correction value representing a difference between a temperature in a use environment and the object temperature to be obtained for the object, and performing a correlation correction process for correcting the object temperature based on the correlation correction value Related to the detection method.

  Another aspect of the present invention is a method for manufacturing a temperature detection device including an infrared sensor, a temperature sensor, and a circuit device for obtaining an object temperature based on an output voltage from the infrared sensor and the temperature sensor. The correction parameter for correcting the object temperature is obtained in the inspection environment, the correction parameter is written in the storage unit of the circuit device, and the circuit device obtains the temperature in the actual use environment of the object and the object. The present invention relates to a method for manufacturing a temperature detection device that writes a correlation correction value representing a difference from the object temperature into the storage unit.

  In another aspect of the present invention, the correlation correction value at each object temperature point of a plurality of object temperature points having different object temperatures may be written in the storage unit.

  In another aspect of the present invention, for each object temperature point, the correlation correction value at each self temperature point of a plurality of self temperature points having different self temperatures may be written in the storage unit.

The structural example of the circuit device of this embodiment and a temperature detection apparatus containing the same. Explanatory drawing of the whole operation | movement of the circuit apparatus of this embodiment. The flowchart of a measurement of a correlation correction value. The flowchart of a correlation correction process. FIG. 5 is a detailed explanatory view of a correlation correction process. FIG. 6A to FIG. 6C are explanatory diagrams of setting parameters for the correlation correction process. Explanatory drawing of the structure of the detection circuit for thermopile. 8A and 8B are explanatory diagrams of the configuration of the thermistor detection circuit. FIG. 9A and FIG. 9B are explanatory diagrams of the temperature detection method of the present embodiment. 10A and 10B show examples of temperature tables stored in the first storage unit and the second storage unit. Explanatory drawing of the detailed process example of the temperature detection method of this embodiment. 1 is a configuration example of an electronic apparatus according to an embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail. The present embodiment described below does not unduly limit the contents of the present invention described in the claims, and all the configurations described in the present embodiment are indispensable as means for solving the present invention. Not necessarily.

1. Circuit Device and Temperature Detection Device FIG. 1 shows a configuration example of a circuit device of this embodiment and a temperature detection device including this circuit device. The circuit device (IC) of this embodiment includes a detection circuit 10 and a control unit 50. Further, the characteristic storage unit 70, the storage unit 80 (parameter storage unit), the output unit 90, and the I / F unit 100 can be included. In addition, the temperature detection device of the present embodiment includes a circuit device, an infrared sensor, and a temperature sensor. As the infrared sensor, a current collecting element type, a thermocouple type, or a bolometer type sensor element may be used. The temperature sensor may use a thermocouple or a thermistor as a sensor element. 1 includes a thermopile 2 as an infrared sensor and a thermistor 4 as a temperature sensor. The thermopile 2 is an element (electric part) that converts heat energy into electric energy. The thermopile 2 can be realized, for example, by connecting a plurality of thermocouples in series (or in parallel). The thermistor 4 is, for example, a resistor whose electrical resistance changes greatly with respect to temperature changes.

  The detection circuit 10 performs detection processing of the thermopile 2 and the thermistor 4. For example, one end (positive electrode side) and the other end (negative electrode side) of the thermopile 2 are electrically connected to the detection circuit 10 via a terminal (pad or the like) of the circuit device. One end of the thermistor 4 is electrically connected to the detection circuit 10 via a terminal (pad or the like) of the circuit device. The other end of the thermistor 4 is connected to a node of the power supply VSS (GND).

  The detection circuit 10 performs A / D conversion on the first detection voltage VD1 detected using the thermopile 2 and outputs a first detection value DT1 as a digital value. The detection circuit 10 performs A / D conversion on the second detection voltage VD2 detected using the thermistor 4, and outputs a second detection value DT2 as a digital value.

  Specifically, the detection circuit 10 includes a thermopile detection circuit 20, a thermistor detection circuit 30, and an A / D conversion circuit 40. The thermopile detection circuit 20 is connected to one end and the other end of the thermopile 2 and outputs the first detection voltage VD1 to the A / D conversion circuit 40. For example, signal amplification of the voltage at both ends of the thermopile 2 is performed, and the first detection voltage VD1 is output. The A / D conversion circuit 40 performs A / D conversion on the first detection voltage VD1, and outputs a first detection value DT1 as a digital value.

  The thermistor detection circuit 30 includes a reference current source 32 (reference current generation circuit). The thermistor detection circuit 30 outputs the second detection voltage VD2 generated when the reference current from the reference current source 32 flows to the thermistor 4 to the A / D conversion circuit 40. The A / D conversion circuit 40 performs A / D conversion on the second detection voltage VD2, and outputs a second detection value DT2 as a digital value.

  The control unit 50 performs various control processes and various arithmetic processes of the circuit device. The control unit 50 can be realized by a logic circuit such as a gate array circuit, a processor, or the like.

  The characteristic storage unit 70 includes a first storage unit 72, a second storage unit 74, and a third storage unit 76. The characteristic storage unit 70 can be realized by a memory such as a ROM. The storage unit 80 stores various parameters. The storage unit 80 can be realized by a non-volatile memory (a memory capable of electrically programming information) such as an OTP (One Time Programmable ROM).

  The output unit 90 D / A converts the temperature detection result measured by the control unit 50 into an analog signal and outputs it to the outside. The I / F (interface) unit 100 performs interface processing with an external device. Through this I / F unit 100, the control unit 50 outputs the temperature detection result as a digital signal to an external device (microcomputer, controller, etc.). In addition, the external device can set various parameters and the like to the circuit device via the I / F unit 100.

  FIG. 2 is a diagram for explaining the overall operation of the circuit device of this embodiment. In the present embodiment, first, after setting and adjusting the function of the circuit device, actual temperature measurement using the thermopile 2 and the thermistor 4 is performed.

  The function setting / adjustment shown in FIG. 2 is performed, for example, when a circuit device (temperature detection device) is manufactured. Specifically, first, various function settings and sensor coefficient parameters of the circuit device are written in the storage unit 80 (OTP) (step S1). The function setting is, for example, a setting of a temperature measurement range, a measurement time, an output format of a temperature measurement result, or the like. The sensor coefficient is a sensitivity coefficient of the thermopile 2 or the like.

  Next, measurement at the control temperature is performed (step S2). The measurement at the control temperature is a measurement (temperature detection process) performed by setting the self temperature (ambient temperature) or the object temperature to a predetermined temperature. For example, the management temperature is a temperature setting such that self temperature = 25 degrees and object temperature = 70 degrees (or self temperature = 25 degrees, object temperature = 25 degrees, etc.). Then, based on the measurement result at the control temperature, a correction parameter for temperature measurement is calculated and written in the storage unit 80 (step S3). The correction parameter is a parameter used when calculating the object temperature or the self temperature based on the detection result of the temperature measurement at the actual temperature measurement.

  Then, the actual temperature measurement is performed using the circuit device that has been set and adjusted in this way (step S4). Then, the control unit 50 performs a correction operation based on the detection results (DT1, DT2) of the detection circuit 10 and the correction parameter obtained in step S3, and outputs a temperature measurement result such as the object temperature or the self temperature. (Step S5).

2. Correlation Correction Processing In the correction calculation in the temperature measurement of FIG. 2, processing for correcting manufacturing variations (individual differences) of the circuit device, the thermopile 2 and the thermistor 4 and correlation correction are performed. Correlation correction is different from correction of manufacturing variation, and further corrects an error between a measured value after correcting manufacturing variation and an actual temperature of an object assumed according to an application. Hereinafter, the correlation correction performed by the present embodiment will be described.

  FIG. 3 shows a flowchart of the correlation correction value measurement (correlation evaluation). This flow is executed in the function setting / adjustment of FIG.

  First, in the inspection environment, a correction parameter used for correcting manufacturing variation is measured (step S31). An inspection environment is an ideal object that does not depend on the application (for example, an object that emits black body radiation) as a temperature measurement target, and that target object is set to a given management temperature. Is the environment where temperature measurement is performed.

  In the measurement in this inspection environment, the temperature actually measured with respect to the control temperature object is different for each solid of the temperature detection device, and a correction parameter for correcting the individual difference is obtained. Then, the correction parameter is written in the storage unit 80 (OTP) (step S32).

  Next, the correlation correction value used for the correlation correction is measured in the actual use environment (step S33). The actual use environment is an environment in which an object that is supposed to be the object to be measured (identical or simulated) in the application of the final product incorporating the temperature detection device is installed, and the temperature of the object is measured. That is. Although it is a measurement in the actual use environment, what is performed in the inspection in the manufacturing process is the same as the measurement in the inspection environment.

  In the measurement in the actual use environment, since the manufacturing variation is corrected by the correction parameter, each solid of the temperature detection device outputs almost the same measurement value for the same object at the same temperature. However, since the object is different from the inspection environment, the actual temperature of the object (for example, the temperature measured by a thermometer that is not the temperature detection device of the present embodiment) and the temperature measured by the temperature detection device are different. For example, an air conditioner can assume indoor walls and people as objects, or an IH heater can assume cooking utensils such as pots and pans as objects. Since these objects do not emit ideal blackbody radiation (the amount of infrared rays is different from a blackbody of the same temperature), the actual temperature of the object differs from the temperature measured by the temperature detector. It will be a thing. In this embodiment, the difference is written in the storage unit 80 (OTP) as a correlation correction value (step S34).

  FIG. 4 shows a flowchart of the correlation correction process using the above-described correlation correction value. This flow is executed in the temperature measurement of FIG.

  First, the self-temperature measurement result and the object temperature measurement result stored in a memory (not shown) such as a RAM are read (steps S41 and S42). These measurement results are the self-temperature and the object temperature after correction of manufacturing variation. For example, in the temperature detection method described later with reference to FIG. 11, the manufacturing variation of the first detection value DT1 due to the thermopile 2 is corrected in steps S14 to S16, and the target in steps S17 to S19 based on the corrected first detection value DT1 and the self temperature. Find the object temperature. The object temperature and the self temperature are temporarily stored in a memory (not shown).

  Next, the correlation correction value is read from the storage unit 80 (OTP), and the object temperature is corrected based on the correlation correction value (step S43). Specifically, a correction value corresponding to the measured self temperature and object temperature is obtained based on the correlation correction value read from the storage unit 80 (OTP), and the correction value is added to the object temperature. Correct the object temperature.

  Next, the correlation-corrected object temperature is output to the outside (step S44). That is, the output unit 90 performs D / A conversion on the target temperature of the digital value subjected to the correlation correction, and outputs the analog output. Alternatively, the correlation-corrected digital object temperature is output to an external device via the I / F unit 100.

3. Details of Correlation Correction Processing The correlation correction processing will be described in more detail with reference to FIGS. 5 to 6C.

  As shown in FIG. 5, in the present embodiment, the first to fourth self-temperature points ta [0] to taj [0] to tobj [3] at the first to fourth object temperature points tobj [0] to tobj [3]. The correlation correction value of ta [3] is measured and stored in the storage unit 80 (OTP). When the correlation correction value of the object temperature point tobj [j] and the self temperature point ta [i] is c [i, j] (i, j is an integer from 0 to 3), c [i, j] Are correlation correction values at 4 × 4 matrix temperature points. Correlation correction values may be used by storing temperature points of a matrix different from the 4 × 4 matrix.

  When performing temperature detection, a correction value corresponding to the measured object temperature and self temperature is obtained from the correlation correction value c [i, j] at the matrix-like temperature points. When the measured object temperature and the self temperature coincide with the temperature point where the correlation correction value exists, the correlation correction value is added to the measured object temperature. If the detected object temperature and the self temperature do not coincide with the temperature point where the correlation correction value exists, the detected object temperature and the self temperature are based on at least one correlation correction value existing around the detected object temperature and the self temperature. A relation correction value may be calculated and added to the measured object temperature. For example, the correlation correction value may be calculated based on the correlation correction value of the temperature point closest to the detected object temperature and self temperature. Alternatively, the correction value may be calculated by performing interpolation processing based on at least two or more correlation correction values at temperature points near the detected object temperature and self temperature.

For example, it is assumed that the object temperature tobA and the self temperature taA are measured. In this case, since the measured value is between the temperature points, the correction value PA is obtained by interpolation. That is, the correction value PA is obtained by the following equation (1) using the four surrounding correction values c [2,2], c [2,3], c [3,2], c [3,3].

When the object temperature tobB and the self temperature taB are measured, since the measured value of the self temperature is outside the matrix, the correction value PB is obtained by extrapolating the self temperature. That is, the correction value PB is obtained by the following equation (2).

Further, when the object temperature tobC and the self temperature taC are measured, since the measured value of the object temperature is outside the matrix, the correction value PC is obtained by extrapolating the object temperature. That is, the correction value PC is obtained by the following equation (3).

  The object temperature point and the self temperature point can be variably set by setting parameters shown in FIGS. 6 (A) and 6 (B). Further, the temperature range and accuracy of the correlation correction value can be variably set by setting parameters shown in FIG. These setting parameters are written in the storage unit 80 (OTP) in the function setting / adjustment of FIG.

  Cor_ta shown in FIG. 6A is a parameter for setting a self-temperature point. Since the self-temperature is a value obtained by measuring the temperature of the thermopile 2, it is influenced by the environmental temperature and the radiation from the object (object temperature). Taking these into consideration, Cor_ta corresponding to the range of the self-temperature used in the actual use environment is set.

  Cor_tobj [2: 0] shown in FIG. 6B is a parameter for setting the interval between the object temperature points. Tst is a parameter for setting the starting temperature of the object temperature point. For example, Cor_tobj [2: 0] and Tst corresponding to the target temperature range to be measured with high accuracy are set according to the application.

  Cor_form [1: 0] shown in FIG. 6C is a parameter for setting a temperature range that can be set as a correlation correction value and a temperature step per 1 LSB of the correlation correction value. Specifically, the measured object temperature is, for example, 12-bit data, and the fifth bit from the LSB is the first integer digit. Cor_form [1: 0] sets, for example, how many bits are added to the object temperature as the first integer digit from the LSB of the correlation correction value, which is 8-bit data. Since the correlation correction value bit7 (MSB) represents a positive or negative sign, it is determined how many times each bit of the lower 7 bits (bit0 to bit6) corresponds. For example, when Cor_form [1: 0] = “00”, the correlation correction value can be set in the range of −63.5 degrees to +63.5 degrees, and the temperature step of 1LSB is 0.5 degrees.

  According to the above embodiment, the detection circuit 10 performs A / D conversion on the first detection voltage VD1 detected using the thermopile 2 (infrared sensor), and outputs the first detection value DT1 as a digital value. Then, A / D conversion is performed on the second detection voltage VD2 detected using the thermistor 4 (temperature sensor), and a second detection value DT2 of a digital value is output. The control unit 50 obtains the object temperature based on the first detection value DT1 and the second detection value DT2. The memory | storage part 80 (OTP) memorize | stores the correlation correction value showing the difference of the temperature in the actual use environment of a target object, and the target object temperature which the control part 50 calculates | requires about a target object. Then, the control unit 50 performs a correlation correction process for correcting the object temperature based on the correlation correction value.

  As described above, the circuit device adjusts the measurement value in the shipping inspection or the like, but the inspection environment and the actual use environment assumed by the user of the circuit device are generally different. For this reason, the actual temperature of the object in the actual use environment may differ from the object temperature detected by the circuit device. In this regard, according to the present embodiment, the object temperature detected by the circuit device can be corrected by storing the correlation correction value representing the difference. Thereby, it becomes possible to correctly measure the temperature of the object according to the application.

  Specifically, the storage unit 80 stores a correlation correction value at each object temperature point among a plurality of object temperature points tobj [0] to tobj [3] having different object temperatures. For example, at the self temperature point ta [0], the correlation correction values c [0,0] to c [0,3] are stored corresponding to tobj [0] to tobj [3]. And the control part 50 performs a correlation correction process based on the correlation correction value in each target object temperature point.

  For example, a black body or the like is an object in the inspection environment, but the difference between the radiation spectrum (infrared spectrum) of the black body and the radiation spectrum of the object in the actual use environment is an error in measurement temperature. Since the difference in spectrum generally depends on the temperature, the measurement temperature error varies depending on the object temperature. In this regard, in the present embodiment, since a plurality of correlation correction values at a plurality of object temperature points can be stored, a highly accurate correlation correction can be performed over a wide temperature range that is actually used.

  Further, the storage unit 80 stores, for each object temperature point, a correlation correction value at each self temperature point of a plurality of self temperature points ta [0] to ta [3] having different self temperatures. For example, tobj [0] stores the correlation correction values c [0,0] to c [3,0] for ta [0] to ta [3]. And the control part 50 performs a correlation correction process based on the self-temperature and the correlation correction value in each self-temperature point.

  In the inspection environment, the measured value is adjusted at a predetermined self temperature (management temperature, for example, 25 degrees). However, the self-temperature varies in an actual use environment. For example, in an air conditioner, the self-temperature varies depending on the temperature, or in an IH heater, the self-temperature increases due to overheated cooking utensils. The electromotive voltage of the thermopile 2 is expressed by a theoretical formula described later in FIG. 9A. In this embodiment, the measured value is calculated on the assumption that an electromotive voltage according to this theoretical formula is obtained. Therefore, as long as this theoretical formula is correct, the measured value is adjusted at the control temperature, and the correct measured value can be obtained even at other self-temperatures. However, since there is a slight error between the electromotive voltage actually obtained and the theoretical formula, an error occurs in the measured temperature at other self-temperatures only by adjusting the measured value at the management temperature. In this respect, in the present embodiment, since a plurality of correlation correction values at a plurality of self-temperature points can be stored, correlation correction according to the self-temperature can be performed, and highly accurate temperature measurement independent of the self-temperature can be performed. .

  As described with reference to FIG. 5, the control unit 50 obtains a correction value (for example, PA) corresponding to the object temperature by interpolation processing of the correlation correction values c [0, 0] to c [3, 3], and Based on the correction value obtained by the interpolation process, the object temperature correlation correction process is performed. For example, two object temperature points tobj [2] and tobj [3] in the vicinity of the measured object temperature tobA are selected, and two object temperature points ta [2] in the vicinity of the measured self temperature taA are selected. , Ta [3]. Then, 2 × 2 correlation correction values c [2,2], c [2,3], c [3,2], c [3,3] at these temperature points are interpolated to obtain a co A relation correction value PA is obtained.

  In this way, the correlation correction value corresponding to the measured object temperature and the self temperature is obtained from the correlation correction value at the temperature point of the matrix composed of the plurality of object temperature points and the plurality of self temperature points. Can be sought. In the present embodiment, a plurality of temperature points are provided to realize highly accurate correlation correction. However, such an interpolation process enables more accurate correlation correction.

  As described with reference to FIG. 6B, the storage unit 80 stores temperature interval information (parameters Cor_tobj [2: 0]) of a plurality of object temperature points tobj [0] to tobj [3]. In addition, the storage unit 80 stores start temperature information (parameter Tst) of a plurality of object temperature points tobj [0] to tobj [3].

  In actual applications, the temperature range to be measured varies. For example, an air conditioner measures the temperature fluctuation range, or an IH heater measures to a high temperature of several hundred degrees. In this regard, according to the present embodiment, since the interval between the object temperature points and the start temperature can be set, the correlation correction value can be arranged in the temperature range according to the application, and the accurate correlation correction is performed in the temperature range. be able to. Alternatively, if there is a temperature range that requires particularly high-accuracy measurement in the temperature range to be used, the correlation correction value can be arranged in that temperature range.

  As described with reference to FIG. 6C, the storage unit 80 sets the temperature range that can be set as the correlation correction value and the setting information (parameter Cor_form [1: 0]).

  Depending on the actual application, the assumed objects differ. For example, in an air conditioner, an indoor wall or the like is an object, or in an IH heater, a cooking utensil or the like is an object. The magnitude of the correlation correction value differs depending on the difference in the object. In this regard, according to the present embodiment, the temperature range that can be set as the correlation correction value can be set, so that the correlation correction value in the temperature range according to the object can be set. When the temperature range to be corrected with the correlation correction value is small, the temperature step of 1 LSB can be reduced by setting the temperature range narrow, and the accuracy of the correlation correction value can be increased.

  As described with reference to FIGS. 3 and 4, the control unit 50 corrects the object temperature based on the correction parameter obtained in the inspection environment, and performs a correlation correction process on the corrected object temperature. . As will be described later with reference to FIG. 11 and the like, the storage unit 80 performs a gain correction process for the temperature characteristics (step S15), a correction process for the offset (step S14), and a conversion process based on the characteristic coefficient parameter GS of the thermopile 2 (step S16). ) Of at least one correction process.

  As described with reference to FIG. 3, manufacturing variations (individual differences among thermopiles, thermistors, and circuit devices) are adjusted using an object that does not depend on the application in the inspection environment. Therefore, when used in an actual usage environment for each application, an error occurs in the measured temperature. In the present embodiment, such an error is corrected by the above-described correlation correction process, thereby enabling accurate temperature measurement.

4). Thermopile detection circuit Hereinafter, the temperature detection method of the present embodiment will be described in detail. First, the detection circuit 10 will be described in detail.

  FIG. 7 shows a configuration example of the thermopile detection circuit 20. The thermopile detection circuit 20 includes an amplification circuit 22, a gain adjustment circuit 24, and a reference voltage generation circuit 26.

  The amplifier circuit 22 is configured by an operational amplifier OPA1 using a switched capacitor circuit, for example. In the amplifier circuit 22 (operational amplifier OPA1), one end (positive terminal) of the thermopile 2 is connected to the first input terminal (inverting input terminal), and the other end of the thermopile 2 is connected to the second input terminal (non-inverting input terminal). (Negative terminal) is connected. The node of the first input terminal of the amplifier circuit 22 is set to the bias voltage VBS. Further, the reference voltage VREF generated by the reference voltage generation circuit 26 is supplied to the amplifier circuit 22 as a reference voltage for the output voltage VAQ.

The amplifier circuit 22 amplifies the electromotive voltage VTP = THPP-THPM generated in the thermopile 2. For example, when the gain of the amplifier circuit 22 is GC (for example, GC = 20), the output voltage VAQ of the amplifier circuit 22 can be expressed as, for example, the following expression (4).
VAQ = -GC · VTP + VREF (4)

  The gain adjustment circuit 24 (programmable gain amplifier) includes an operational amplifier OPA2 and resistors RA1 and RA2. One end of the resistor RA1 is connected to the output terminal of the amplifier circuit 22 (operational amplifier OPA1), and the other end of the resistor RA1 is connected to the first input terminal (inverting input terminal) of the operational amplifier OPA2. One end of the resistor RA2 is connected to the first input terminal of the operational amplifier OPA2, and the other end of the resistor RA2 is connected to the output terminal of the operational amplifier OPA2. The reference voltage VREF generated by the reference voltage generation circuit 26 is supplied to the second input terminal (non-inverting input terminal) of the operational amplifier OPA2. The resistor RA2 is a variable resistor whose resistance value is variable. By setting the resistance value of the resistor RA2, the gain of the gain adjusting circuit 24 is set.

The gain adjustment circuit 24 amplifies the output voltage VAQ of the amplification circuit 22 with a set gain with reference to the reference voltage VREF, and outputs a first detection voltage VD1. For example, when the resistance values of the resistors RA1 and RA2 are R1 and R2, the gain of the gain adjustment circuit 24 is GA = R2 / R1. Therefore, the first detection voltage VD1 that is the output voltage of the gain adjustment circuit 24 can be expressed as the following equation (5).
VD1 =-(R2 / R1). (VAQ-VREF) + VREF
= -GA. (VAQ-VREF) + VREF (5)

From the above equations (4) and (5), the first detection voltage VD1 can be expressed as the following equation (6).
VD1 = GC / GA / VTP + VREF (6)

  The A / D conversion circuit 40 performs A / D conversion for the first detection voltage VD1. Then, the first detection value DT1 (first voltage data), which is a digital value obtained by A / D conversion of the first detection voltage VD1, is output to the control unit 50. The A / D conversion circuit 40 also performs A / D conversion on the reference voltage VREF and outputs a digital value corresponding to the reference voltage VREF to the control unit 50.

  Although the offset voltage of the amplifier circuit 22 (the operational amplifier OPA1) and the gain adjustment circuit 24 has not been described in detail above, the control unit 50 also performs correction processing (offset cancellation processing) of these offset voltages. . Further, the values of the gain GA and the reference voltage VREF of the gain adjustment circuit 24 can be variably set via the I / F unit 100 of FIG. Thereby, the gain GA and the reference voltage VREF can be set in consideration of the sensitivity, temperature range, accuracy, and the like of the thermopile 2.

5. Thermistor Detection Circuit FIGS. 8A and 8B are diagrams illustrating the configuration of the thermistor detection circuit 30. As shown in FIG. 8A, the thermistor detection circuit 30 includes a reference current source 32. A voltage generated when the reference current IREF from the reference current source 32 flows to the thermistor 4 is output to the A / D conversion circuit 40 as the second detection voltage VD2. Then, the A / D conversion circuit 40 performs A / D conversion on the second detection voltage VD2, and sends the second detection value DT2 of the digital value obtained by the A / D conversion of the second detection voltage VD2 to the control unit 50. Output. The control unit 50 obtains the self temperature by referring to the third storage unit 76 (ROM 3) based on the second detection value DT2. For example, FIG. 8B is a diagram illustrating an example of temperature characteristics of the detection voltage of the thermistor 4. As shown in FIG. 8B, the self temperature can be obtained from the detection voltage of the thermistor 4. For example, the third storage unit 76 stores the self-temperature value and the second detection value DT2 (VD2) in association with each other. For example, a temperature table in which the self-temperature value is associated with the second detection value DT2 is stored. Therefore, the control unit 50 can obtain the self temperature by using the second detection value DT2 from the A / D conversion circuit 40 and the third storage unit 76. For example, the self temperature can be obtained by searching the self temperature value corresponding to the second detection value DT2 using, for example, a temperature table stored in the third storage unit 76.

6). Next, the temperature detection method (temperature detection method) of this embodiment will be described in detail. In the present embodiment, the object temperature and the self temperature are detected by the method described below.

  FIG. 9A is an example of a calculation formula (theoretical formula) for the electromotive voltage VTP (electromotive force) generated by the thermopile 2. TP is an object temperature, TTH is a self-temperature (thermistor temperature), and S is a characteristic coefficient of the thermopile 2. The characteristic coefficient S (unit: V) corresponds to the electromotive voltage generated by the thermopile 2 when the self temperature TTH = 25 degrees and the object temperature TP = 70 degrees, for example. G is a characteristic variation coefficient (0.8 to 1.2), and VTPOF is an offset voltage of the thermopile 2. G corresponds to gain variation. VTPOF corresponds to an electromotive voltage generated by the thermopile 2 when, for example, the self temperature TTH and the object temperature TP are equal (for example, TTH = TP = 25 degrees). These G and VTPOF affect the electromotive voltage VTP as an element variation factor of the thermopile 2.

  As shown in FIG. 9B, the electromotive voltage VTP includes a first electromotive voltage VTP0 that is an electromotive voltage of the thermopile alone, a second electromotive voltage VTH that is an electromotive voltage generated by the self temperature TTH, and an offset voltage V0 ( = VTPOF). The first electromotive voltage VTP0 is an electromotive voltage generated by a temperature difference between the object temperature TP and the self temperature TTH. The second electromotive voltage VTH is an electromotive voltage caused only by the self temperature TTH. The offset voltage V0 is an electromotive voltage that is generated even when the temperature difference between the object temperature TP and the self temperature TTH is zero.

  S in FIG. 9B has a different meaning from the characteristic coefficient S of the thermopile 2 in FIG. 9A, and S in FIG. 9B is a ROM when temperature data is stored in the characteristic storage unit 70. The coefficient S.

  In the present embodiment, for example, the calculation result of the first electromotive voltage VTP0 when the ROM coefficient S = 472 and G = 1.0 is stored in the first storage unit 72 as temperature determination data. Specifically, the value of the object temperature TP and the value of the first electromotive voltage VTP0 are stored in the first storage unit 72 in association with each other.

  Further, the calculation result of the second electromotive voltage VTH when S = 472 and G = 1.0 is stored in the second storage unit 74 as temperature determination data. Specifically, the value of the self-temperature TTH and the value of the second electromotive voltage VTH are stored in the second storage unit 74 in association with each other.

  10A and 10B show examples of temperature tables (temperature determination data) stored in the first storage unit 72 and the second storage unit 74. FIG. As shown in FIG. 10A, for example, when −31 degrees ≦ TP <204 degrees, the ROM coefficient S = 472, and the ROM 1 (TP value) which is the value (ROM value) of the first electromotive voltage VTP 0 at each object temperature TP. ). On the other hand, for example, when 204 degrees ≦ TP ≦ 401 degrees, ROM1 (TP) is calculated with ROM coefficient S = 118. As shown in FIG. 10B, ROM2 (TTH), which is the value (ROM value) of the second electromotive voltage VTH at each self-temperature TTH, for example, is calculated at −21 degrees ≦ TTH ≦ 106 degrees.

  The number of significant digits of the first storage unit 72 (second storage unit 74) is 12 bits = 4096, and the ROM coefficient S = 472 is set so that ROM1 (TP) is within 12 bits = 4096. Yes. In this case, when the object temperature TP becomes 204 degrees, ROM1 (TP) = 4103, which exceeds the effective number of bits of 12 bits = 4096. Therefore, when TP ≧ 204 degrees, the ROM coefficient S = 472/4 = 118. Is set. Then, the case where TP ≧ 204 degrees is dealt with by doubling the measurement result to be determined at the time of temperature determination.

  In this embodiment, paying attention to the fact that the electromotive voltage VTP of the thermopile 2 can be expressed as shown in FIG. 9B, a temperature detection method described below is adopted.

  First, in the present embodiment, as described with reference to FIG. 1, the first detection voltage VD1 and the second detection voltage VD2 detected using the thermopile 2 and the thermistor 4 are subjected to A / D conversion to obtain the first A detection value DT1 and a second detection value DT2 are obtained. The first detection value DT1 corresponds to the electromotive voltage VTP.

  Then, the self temperature TTH is obtained from the second detection value DT2. For example, as described with reference to FIGS. 8A and 8B, the self-temperature TTH corresponding to the second detection value DT2 obtained by A / D converting the second detection voltage VD2 of the thermistor 4 is obtained. By searching for the value using the temperature table of the third storage unit 76, the self temperature TTH is obtained.

  Next, a value of the second electromotive voltage VTH corresponding to the self temperature TTH is obtained based on the obtained self temperature TTH. Specifically, as described in FIG. 9B, the value of the second electromotive voltage VTH corresponding to the self temperature TTH is read from the second storage unit 74 based on the value of the self temperature TTH. That is, the value of the second electromotive voltage VTH is calculated in advance with the ROM coefficient S = 472, and stored in the second storage unit 74 in association with the value of the self temperature TTH. Then, based on the self-temperature TTH obtained based on the second detection value DT2, the value of the corresponding second electromotive voltage VTH is read from the second storage unit 74.

  Then, based on the first detection value DT1 (VTP) and the obtained value of the second electromotive voltage VTH, the value of the first electromotive voltage VTP0 corresponding to the object temperature TP is obtained. For example, as is apparent from the equation shown in FIG. 9B, the value of the second electromotive voltage VTH is added to the value of the electromotive voltage VTP corresponding to the first detection value DT1, and the value of the offset voltage V0 (VTPOF) is obtained. By subtracting, the value of the first electromotive voltage VTP0 can be obtained.

  Next, the object temperature TP is obtained based on the obtained value of the first electromotive voltage VTP0. Specifically, the object temperature TP is obtained by searching the value of the object temperature TP corresponding to the value of the first electromotive voltage VTP0 using the temperature table of the first storage unit 72. That is, as the ROM coefficient S = 472 (118), the value of the first electromotive voltage VTP0 is calculated in advance and stored in the first storage unit 72 in association with the value of the object temperature TP. Then, the value of the object temperature TP corresponding to the value of the first electromotive voltage VTP0 obtained from the first detection value DT1 (VTP) and the second electromotive voltage VTH (and the offset voltage V0) is stored in the first storage unit 72. The object temperature TP is obtained by searching using the temperature table.

  As described above, in the present embodiment, the object temperature TP and the self-temperature TTH are obtained from the first detection voltage VD1 of the thermopile 2 and the second detection voltage VD2 of the thermistor 4. Thereby, even when the thermopile 2 having various characteristic coefficients is used, the object temperature TP can be obtained with a small processing load.

  That is, as a method of the comparative example of the present embodiment, a method of obtaining the object temperature TP only by analog processing by an analog circuit can be considered. However, in the method of this comparative example, since temperature correction or the like is performed only by gain adjustment, it is difficult to perform adjustment processing in accordance with a wide temperature range and the characteristic coefficient of the thermopile 2.

  On the other hand, in the present embodiment, the first detection voltage VD1 of the thermopile 2 and the second detection voltage VD2 of the thermistor 4 are converted into the first detection value DT1 and the second detection value DT2 of digital values, and are processed by digital processing. The object temperature TP is obtained. Specifically, as shown in FIG. 9B, the object of the object is effectively utilized by dividing the expression of the electromotive voltage VTP into the terms of the first electromotive voltage VTP0, the second electromotive voltage VTH, and the offset voltage V0. The temperature TP is obtained. Therefore, compared to the method of the comparative example in which the object temperature TP is obtained by analog processing using an analog circuit, the object temperature TP can be obtained with high accuracy even when the thermopile 2 having various characteristic coefficients is used. Become. That is, in the method of the comparative example, when the circuit constant of the analog circuit is set in accordance with the thermopile 2 having a specific characteristic coefficient, it is difficult to deal with the thermopile 2 having a characteristic coefficient different from this setting. On the other hand, in the present embodiment, the object temperature TP is obtained by digital processing using the first detection value DT1 and the second detection value DT2. Accordingly, the object temperature TP can be obtained with high accuracy by performing correction processing corresponding to the thermopile 2 having various characteristic coefficients.

  For example, in this embodiment, as described with reference to FIGS. 10A and 10B, the ROM coefficient S is set to a specific value (for example, S = 472, S = 118), and FIG. ) Of the first electromotive voltage VTP0 and the second electromotive voltage VTH (temperature table) are calculated and stored in the first storage unit 72 and the second storage unit 74. Further, in order to cope with the thermopile 2 having various characteristic coefficients, a characteristic coefficient parameter GS of the thermopile 2 described later is prepared. The characteristic coefficient parameter GS is written in the storage unit 80 (OTP) when the circuit device is manufactured, for example. Then, during actual temperature measurement, a conversion process based on the characteristic coefficient parameter GS is performed on the first detection value DT1, and based on the first detection value DT1 subjected to the conversion process and the value of the second electromotive voltage VTH, The value of the first electromotive voltage VTP0 is obtained. Then, the object temperature TP is obtained by searching the value of the object temperature TP corresponding to the obtained value of the first electromotive voltage VTP0 using the temperature table of the first storage unit 72.

  In this way, even when the thermopile 2 having various characteristic coefficients is used, the characteristic temperature parameter GS is set to a value corresponding to the thermopile 2 and the correction process is executed, whereby the object temperature TP Can be obtained with high accuracy. In addition, the first storage unit 72 and the second storage unit 74 need only store the calculation results when the ROM coefficient S is a specific value. Therefore, the used storage capacity of the first storage unit 72 and the second storage unit 74 can be saved, and the first storage unit 72 and the second storage unit 74 having a small storage capacity can be used to control the object temperature TP by digital processing. Arithmetic processing can be realized.

  Further, according to the present embodiment, the storage unit is divided into two first storage units 72 and second storage units 74, and the first storage unit 72 stores the calculation result for the first electromotive voltage VTP0, and the second storage unit 72 The storage unit 74 stores a calculation result for the second electromotive voltage VTH. Then, as shown in FIG. 9B, the object temperature TP is obtained by utilizing the fact that the expression of the electromotive voltage VTP is divided into terms such as the first electromotive voltage VTP0 and the second electromotive voltage VTH. Therefore, it is possible to simplify the arithmetic processing for obtaining the object temperature TP, and to obtain the object temperature TP with high accuracy while reducing the processing load of the control unit 50.

7). Detailed Processing Example Next, a detailed processing example of the temperature detection method of the present embodiment will be described with reference to FIG.

First, the electromotive voltage VTP generated by the thermopile 2 is detected and amplified by the amplification circuit 22 and the gain adjustment circuit 24 (PGA) of the detection circuit 10 (step S11). The first detection voltage VD1 after amplification can be expressed as the following formula (7).
VD1 = VREF + VTP × GC × GA (7)

  Here, GC is the gain of the amplifier circuit 22, and GA is the gain of the gain adjustment circuit 24.

Next, the amplified first detection voltage VD1 is input to the A / D conversion circuit 40, and A / D converted to the first detection value DT1 as a digital value (step S12). The first detection value DT1, which is the A / D conversion result, can be expressed as in the following equation (8).
DT1 = (VD1 / VD28) × 4096
= (VREF + VTP × GC × GA) / VD28 × 4096 (8)

  VD28 is an input full-scale voltage (input voltage range) of the A / D conversion circuit 40. For example, VD28 = 2.8V. Note that the bias voltage in FIG. 7 is set to VBS = VD28 / 2, for example. The A / D conversion circuit 40 is a circuit that performs 12-bit (= 4096) A / D conversion, and has a resolution of VD28 / 4096.

Next, as shown in the following equation (9), a portion related to the reference voltage VREF (A / D conversion value ADVREF corresponding to VREF) is subtracted from the first detection value DT1 which is the A / D conversion result (step S13). ).
DT1-ADVREF
= (VREF + VTP × GC × GA) / VD28 × 4096−ADVREF
= (VTP x GC x GA) / VD28 x 4096 (9)

Here, as described with reference to FIG. 9B, VTP can be expressed as the following equation (10).
VTP = VTP0−VTH + V0 (10)

Therefore, the above equation (9) can be expressed as the following equation (11) by substituting the above equation (10).
{(VTP0−VTH + V0) × GC × GA} / VD28 × 4096 (11)

Next, a process of subtracting the portion related to the offset voltage V0 of the thermopile 2 (AD converted value ADVTPOF corresponding to VTPOF) is performed (step S14). This is a process of subtracting ADVTPOF from the above equation (11) as shown in the following equation (12).
{(VTP0−VTH + V0) × GC × GA} / VD28 × 4096-ADVTPOF
= {(VTP0−VTH) × GC × GA} / VD28 × 4096 (12)

  The ADVTPOF subtracted here can include offset voltages (residual offset voltages) of the operational amplifiers OPA1 and OPA2 of the thermopile detection circuit 20 of FIG. 7 in addition to the offset voltage of the thermopile 2.

  Next, gain correction is performed using the gain correction parameter GAJ (step S15). The gain correction parameter GAJ is a parameter for correcting gain variation (temperature characteristic gradient). That is, the actual device gain varies with respect to the designed gain. Therefore, as shown in step S2 of FIG. 2, the actual device is measured at the management temperature, and the gain correction parameter GAJ of the actual device is calculated based on the measurement result. Then, at the actual temperature measurement in step S4 in FIG. 2, as shown in step S5, the temperature measurement result is corrected using the gain correction parameter GAJ and the like.

Next, in order to determine the temperature value with the temperature determination data (temperature table) of the first storage unit 72 and the second storage unit 72, a process of multiplying the characteristic coefficient parameter GS is performed (step S16). This is a process of multiplying the above equation (12) by the characteristic coefficient parameter GS as shown in the following equation (13). The value after multiplying by the characteristic coefficient parameter GS is described as ROM (VTP0−VTH). By multiplying by GS, it is converted into a value suitable for the ROM value.
{(VTP0−VTH) × GC × GA} / VD28 × 4096 × GS
= ROM (VTP0-VTH) (13)

Here, the characteristic coefficient parameter GS can be expressed as the following formula (14).
GS = {(472/4096) × VD28)} / (S × GC × GA) (14)

  The characteristic coefficient parameter GS is a conversion coefficient for matching the A / D conversion result value with the temperature table stored in the first storage unit 72 or the like. As shown in the above equation (14), the characteristic coefficient parameter GS is set according to S representing the characteristics of the thermopile 2 and gains GC and GA of signal amplification in the detection circuit 10. Specifically, in step S1 of FIG. 2, the characteristic coefficient parameter GS is written as a sensor coefficient in the storage unit 80 (OTP) at the time of manufacture. In this case, the value of the characteristic coefficient parameter GS to be written is set for each product according to the circuit constants (GC, GA) of the circuit device and the characteristics (sensitivity) of the thermopile 2 used by the circuit device. .

  Next, the ROM (VTH), which is the value of the second electromotive voltage VTH, is obtained by referring to the second storage unit 74 based on the value of the self-temperature TTH obtained from the second detection value DT2 of the thermistor detection circuit 30. (Step S17). For example, in the temperature table of the second storage unit 74 shown in FIG. 10B, if the ROM value corresponding to the self temperature TTH is ROM2 (TTH), then ROM (VTH) = ROM2 (TTH).

Next, as shown in the following equation (15), ROM (VTH) is added to ROM (VTP0−VTH) which is a value after multiplying by the characteristic coefficient parameter GS, and the first of the thermopile 2 itself is added. The value of the electromotive voltage VTP0 is obtained (step S18). A value obtained by this addition is described as ROM (VTP0).
ROM (VTP0−VTH) + ROM (VTH) = ROM (VTP0) (15)

  Next, the object temperature TP is obtained using the ROM (VTP0) obtained as in the above equation (15) and the temperature table (temperature determination data) of the first storage unit 72 (step S19). For example, ROM1 (TP), which is a ROM value corresponding to each object temperature TP, is sequentially read using the temperature table of the first storage unit 72 shown in FIG. Then, the ROM (VTP0) and the read ROM1 (TP) are compared, and the temperature at which ROM (VTP0) = ROM1 (TP) is obtained as the object temperature TP. In addition, you may obtain | require the temperature corresponding to ROM1 (TP) from which the difference of the value of ROM (VTP0) and ROM1 (TP) becomes the minimum as object temperature TP. Further, interpolation calculation may be performed from a plurality of ROM1 (TP) data, and the temperature corresponding to the ROM (VTP0) may be obtained as the object temperature TP.

  Next, the correlation correction of the object temperature TP is performed based on the obtained object temperature TP and the self temperature TTH, and the corrected object temperature TPC is output (step S20). That is, the correlation correction value used for the correlation correction is selected from the object temperature TP and the self temperature TTH, read out from the storage unit 80 (OTP), and the object correction temperature is interpolated to interpolate the object temperature TP and the self temperature TTH. Correlation correction value corresponding to is obtained, and the correlation correction value is added to the object temperature TP.

  In the method of the present embodiment described above, for example, ROM coefficients S and G in FIG. 9B are set to predetermined values (for example, S = 472, G = 1.0), and VTP0 in the equation in FIG. , VTH values are obtained, and the obtained VTP0 and VTH values are stored in the first storage unit 72 and the second storage unit 74 as shown in FIGS. 10 (A) and 10 (B).

  Further, based on the gains GC and GA which are circuit constants of the circuit device and the characteristic coefficient S of the thermopile 2 used, the characteristic coefficient parameter GS described in the above equation (14) = {(472/4096) × VD28) } / (S × GC × GA). Then, the obtained characteristic coefficient parameter GS is written in the storage unit 80 (OTP) as a sensor coefficient parameter when the circuit device is manufactured, as shown in step S1 of FIG. As a result, an appropriate characteristic coefficient parameter GS corresponding to the product specifications of each circuit device (each temperature detection device) is stored in the storage unit 80. Accordingly, it is possible to deal with the thermopile 2 having various characteristics while saving the used storage capacity of the first storage unit 72 and the second storage unit 74, and it is possible to cope with various product specifications.

  Further, measurement is performed at a control temperature as shown in step S2 of FIG. 2, and correction parameters for correcting element variations are calculated as shown in step S3. Specifically, the gain correction parameter GAJ in step S15 in FIG. 2, the offset voltage (ADVTPOF) in step S14, and the like are obtained as correction parameters. That is, there are variations due to element variations in the characteristic coefficient S such as the sensitivity of the thermopile 2, circuit constants such as the gains GC and GA of the detection circuit 10, and the offset voltage. Therefore, as shown in step S2 of FIG. 2, measurement is performed at the management temperature, and a correction parameter is obtained based on the measurement result and written in the storage unit 80 (OTP). Then, as shown in step S <b> 5, at the actual temperature measurement, the temperature measurement result is corrected based on the correction parameter stored in the storage unit 80. By doing so, even when the characteristic coefficient S of the thermopile 2, the circuit constant of the detection circuit 10, or the offset voltage varies, the temperature measurement result such as the object temperature TP can be obtained with higher accuracy. It becomes possible.

8). Electronic Device FIG. 12 shows a configuration example of an electronic device including the circuit device 210 and the temperature detection device 200 of this embodiment. The electronic device includes a processing unit 300, a storage unit 310, an operation unit 320, an input / output unit 330, a bus 340, and the temperature detection device 200. The temperature detection device 200 includes the circuit device 210, the thermopile 2, and the thermistor 4 of the present embodiment.

  Electronic devices to which this embodiment is applied include air conditioner equipment such as air conditioners, IH equipment such as IH cookers and IH rice cookers, FAX devices, printing devices, thermometers, human detection devices, flame detection devices, and gas. Various devices such as a detection device or a light meter can be assumed.

  The processing unit 300 performs various control processes and arithmetic processes of the electronic device, and is realized by a processor such as an MPU or an ASIC such as a display controller. The processing unit 300 performs various processes based on the temperature measurement results such as the object temperature and the self temperature detected by the temperature detection device 200.

  The storage unit 310 is a storage area of the processing unit 300 and the like, and is realized by, for example, a DRAM, an SRAM, an HDD, or the like. The operation unit 320 is used by the user to input various operation information. The input / output unit 330 exchanges data and the like with the outside, and is realized by a wired interface (USB or the like), a wireless communication unit, or the like.

  Although the present embodiment has been described in detail as described above, it will be easily understood by those skilled in the art that many modifications can be made without departing from the novel matters and effects of the present invention. Accordingly, all such modifications are intended to be included in the scope of the present invention. For example, a term described at least once together with a different term having a broader meaning or the same meaning in the specification or the drawings can be replaced with the different term in any part of the specification or the drawings. In addition, the configurations and operations of the circuit device, the temperature detection device, and the electronic device are not limited to those described in the present embodiment, and various modifications can be made.

2 Thermopile, 4 Thermistor, 10 Detection circuit,
20 Thermopile detection circuit, 22 amplification circuit, 24 gain adjustment circuit,
26 reference voltage generation circuit, 30 detection circuit for thermistor, 32 reference current source,
40 A / D conversion circuit, 50 control unit, 70 characteristic storage unit, 72 first storage unit,
74 second storage unit, 76 third storage unit, 80 storage unit, 90 output unit,
100 I / F unit, 200 temperature detection device, 210 circuit device, 300 processing unit,
310 storage unit, 320 operation unit, 330 input / output unit, 340 bus,
DT1 first detection value, DT2 second detection value, TP object temperature, TTH self temperature,
VD1 first detection voltage, VD2 second detection voltage, electromotive voltage of VTP thermopile,
c [0,0] to c [3,3] correlation correction value,
ta [0] to ta [3] self temperature point,
tobj [0] to tobj [3] Object temperature point

Claims (11)

A / D conversion is performed on the first detection voltage detected using the infrared sensor, and the first detection value of the digital value is output, and the A / D regarding the second detection voltage detected using the temperature sensor. A detection circuit that performs conversion and outputs a second detection value of the digital value;
A control unit for obtaining an object temperature based on the first detection value and the second detection value;
A storage unit that stores a correlation correction value that represents a difference between a temperature of the target in an actual use environment and the target temperature that the control unit calculates for the target;
Including
The storage unit
The correlation correction value at each object temperature point of a plurality of object temperature points with different object temperatures, and the respective self temperature points of a plurality of self temperature points with different self temperatures at each object temperature point Correlation correction value,
Remember
The controller is
At each object temperature point, the self temperature is obtained based on the second detection value, and the object temperature is corrected based on the self temperature and at least one correlation correction value at each self temperature. A circuit device characterized by performing a correlation correction process. In claim 1 ,
The controller is
A correction value corresponding to the object temperature is obtained by interpolation processing of the correlation correction value, and the correlation correction processing of the object temperature is performed based on the correction value obtained by the interpolation processing. Circuit device. In claim 1 or 2 ,
The storage unit
A circuit device for storing temperature interval information of the plurality of object temperature points. In claim 3 ,
The storage unit
A circuit device for storing start temperature information of the plurality of object temperature points. In any one of Claims 1 thru | or 4 ,
The storage unit
A circuit device that stores setting information for variably setting a temperature range that can be set as the correlation correction value and a temperature increment per LSB of the correlation correction value. In any one of Claims 1 thru | or 5 ,
The controller is
A circuit device that corrects the object temperature based on a correction parameter obtained in an inspection environment, and performs the correlation correction process on the corrected object temperature. In claim 6 ,
The storage unit
Storing the correction parameter of at least one correction process of a gain correction process for temperature characteristics, a correction process for offset, and a conversion process based on a characteristic coefficient parameter of a thermopile as the correction parameter obtained in the inspection environment. A circuit device characterized. A circuit device according to any one of claims 1 to 7 ,
The infrared sensor;
The temperature sensor;
A temperature detecting device comprising: An electronic apparatus comprising the circuit arrangement as claimed in any one of claims 1 to 7. A / D conversion is performed on the first detection voltage detected using the infrared sensor, and the first detection value of the digital value is output, and the A / D regarding the second detection voltage detected using the temperature sensor. Perform the conversion and output the second detected value of the digital value;
Based on the first detection value and the second detection value, an object temperature is obtained,
As a correlation correction value representing a difference between the temperature in the actual use environment of the object and the object temperature to be obtained for the object, a plurality of object temperature points having different object temperatures at each object temperature point Storing the correlation correction value and the correlation correction value at each self-temperature point of a plurality of self-temperature points having different self-temperatures at each object temperature point ;
At each object temperature point, the self temperature is obtained based on the second detection value, and the object temperature is corrected based on the self temperature and at least one correlation correction value at each self temperature. A temperature detection method characterized by performing a correlation correction process. An infrared sensor, a temperature sensor, and a circuit device for obtaining an object temperature based on an output voltage from the infrared sensor and the temperature sensor,
Determining a correction parameter for correcting the object temperature in an inspection environment;
Write the correction parameter to the storage unit of the circuit device,
Each object of a plurality of object temperature points with different object temperatures as a correlation correction value representing a difference between the temperature of the object in the actual use environment and the object temperature required by the circuit device for the object The correlation correction value at an object temperature point and the correlation correction value at each self temperature point of a plurality of self temperature points having different self temperatures at each object temperature point are written in the storage unit. Manufacturing method of the temperature detecting device.

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