JP6963488B2 - Temperature measuring device - Google Patents

Description

The present invention relates to a temperature measuring device.

Conventionally, a technique has been known in which a diode, a thermistor, or the like is used as a temperature sensor, and the temperature of the ambient environment is measured by utilizing the change in the electric signal output by the temperature sensor as the temperature of the ambient environment changes (for example, patent documents). See 1).

Japanese Unexamined Patent Publication No. 7-158966

Here, depending on the characteristics of the temperature sensor, the voltage range that the electric signal can take according to the ambient temperature change does not match the input voltage range of the conversion target of the A / D conversion circuit that A / D-converts the electric signal. There was a case. In this case, there is a problem that the resolution of the temperature indicated by the digital value converted in the A / D conversion circuit becomes lower than the resolution originally possessed by the A / D conversion circuit.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a temperature measuring device capable of A / D converting an electric signal corresponding to a temperature change in an ambient environment with high resolution.

In order to solve the above problems, the temperature measuring device according to one aspect of the present invention includes a temperature detecting unit for detecting a temperature, a temperature signal indicating the temperature detected by the temperature detecting unit, and a first reference voltage. Amplifies the first amplified signal based on the difference between the first amplifier that amplifies the temperature signal, the first amplified signal amplified by the first amplifier, and the second reference voltage based on the difference between the two. The first reference voltage is fixed to a predetermined voltage, and the A / D is provided. The conversion circuit is a voltage corresponding to the lower limit of the input voltage range capable of A / D conversion, the second reference voltage is fixed to a predetermined voltage, and the A / D conversion circuit is capable of A / D conversion. This is the voltage corresponding to the upper limit of the input voltage range.

The first reference voltage may be a voltage having the same potential as the ground potential.

The second reference voltage may be a voltage having the same potential as the reference voltage applied to the A / D conversion circuit.

The second reference voltage may be a voltage supplied from a reference voltage supply unit that supplies an operation reference voltage of the A / D conversion circuit.

The temperature detection unit is a diode, and the temperature signal may include the forward voltage of the diode at a certain reference temperature as an offset.

The temperature detection unit is a thermistor, and the temperature signal may include a voltage generated across the thermistor at a certain reference temperature as an offset.

A light receiving / emitting unit that receives infrared rays emitted by a temperature measurement target or emits infrared rays to the measurement target, and the measurement target based on the intensity of the infrared rays received or emitted by the light receiving / emitting unit. The infrared energy difference acquisition unit that acquires the infrared energy difference, the ambient environment temperature acquisition unit that acquires the temperature of the ambient environment of the own device based on the value output by the A / D conversion circuit, and the infrared energy difference acquisition unit. The target temperature acquisition unit that acquires the temperature of the measurement target and the target temperature acquisition unit based on the infrared energy difference acquired by the unit and the temperature of the ambient environment acquired by the ambient environment temperature acquisition unit. An output unit that outputs information indicating the temperature of the measurement target acquired by the above may be provided.

The light receiving / receiving unit may be a thermopile sensor.

The temperature measuring device according to each aspect of the present invention can appropriately change the electric signal of the temperature sensor within the range of the temperature change in the ambient environment.

It is a figure which shows an example of the temperature measuring apparatus of this embodiment. It is a figure which shows an example of the structure of the ambient temperature measurement processing part of this embodiment. It is a figure which shows an example of the temperature characteristic of the diode of this embodiment. It is a figure which shows an example of the adjustment of the temperature signal of this embodiment. It is a figure which shows an example of the reference voltage of the A / D conversion circuit of this embodiment.

[Embodiment]
Hereinafter, the temperature measuring device according to the embodiment of the present invention will be described in detail with reference to the drawings.

<1. Overview of temperature measuring device>
FIG. 1 is a diagram showing an example of the temperature measuring device 1 of the present embodiment.
The temperature measuring device 1 measures the temperature of the object for temperature measurement (measurement object P shown in the figure). Specifically, the temperature measuring device 1 measures the temperature of the measuring object P in a non-contact manner without the temperature measuring device 1, the sensor, or the like coming into contact with the measuring object P. As shown in FIG. 1, it includes an ambient temperature measurement processing unit 10, an energy difference measurement processing unit 20, and a control unit 30.

The ambient temperature measurement processing unit 10 is an electric circuit that measures the temperature of the ambient environment (hereinafter referred to as the ambient temperature) in which the temperature measuring device 1 is installed. The ambient temperature measurement processing unit 10 includes a temperature detection circuit 11, an offset gain adjustment circuit 12, and an A / D conversion circuit 13. The temperature detection circuit 11 includes, for example, a temperature detection unit that detects the temperature and a peripheral circuit for operating the temperature detection unit. The temperature detection circuit 11 is an electric signal output by the temperature detection unit, and outputs an electric signal indicating the ambient temperature. In the following description, the electric signal output by the temperature detection circuit 11 is also simply referred to as a temperature signal.

The offset gain adjustment circuit 12 is a circuit that adjusts the temperature signal based on the offset voltage superimposed on the temperature signal. The A / D conversion circuit 13 converts the temperature signal output by the offset gain adjustment circuit 12 into a digital signal. The A / D conversion circuit 13 supplies the converted digital signal to the control unit 30 as information indicating the ambient temperature.

Here, the voltage range of the analog signal (hereinafter referred to as the input voltage range) in which the A / D conversion circuit 13 can convert the analog signal into the digital signal may be different from the voltage range that the temperature signal can take. For example, the voltage range that the temperature signal can take may be narrower than the input voltage range of the A / D conversion circuit 13. In this case, it may be difficult for the A / D conversion circuit 13 to A / D convert the change in the ambient temperature with high resolution. The offset gain adjusting circuit 12 adjusts the temperature signal so that the range that the temperature signal can take matches the input voltage range of the A / D conversion circuit 13. In this embodiment, the input voltage range is from ground potential to voltage VD. The voltage VD is a voltage used when operating the ambient temperature measurement processing unit 10. Specifically, the input voltage range is 0 to 4.1 [V].

The energy difference measurement processing unit 20 is an electric circuit including a thermopile sensor 21, an amplifier circuit 22, and an A / D conversion circuit 23, and measures the difference in infrared energy between the measurement object P and the thermopile sensor 21. .. When the measurement object P is higher than the temperature of the thermopile sensor 21, the thermopile sensor 21 receives the infrared rays emitted by the measurement object P. In this case, the thermopile sensor 21 outputs a positive voltage according to the intensity of the received infrared rays. When the temperature of the measurement object P is lower than the temperature of the thermopile sensor 21, the thermopile sensor 21 emits infrared rays to the measurement object P. In this case, the thermopile sensor 21 outputs a negative voltage according to the intensity of the emitted infrared rays. That is, the thermopile sensor 21 generates an electric signal indicating an infrared energy difference between the measurement object P and the thermopile sensor 21. The amplifier circuit 22 amplifies the electric signal output from the thermopile sensor 21 at a predetermined amplification factor. The A / D conversion circuit 23 converts the electric signal amplified by the amplifier circuit 22 into a digital signal. The A / D conversion circuit 23 supplies the converted digital signal to the control unit 30 as information indicating an infrared energy difference.

The control unit 30 is realized by, for example, a hardware processor such as a CPU (Central Processing Unit) executing a program (software) stored in a storage unit (not shown). The control unit 30 includes an ambient environment temperature acquisition unit 31, an infrared energy difference acquisition unit 32, a target temperature acquisition unit 33, and an output unit 34 as its functional units. Some or all of these components (excluding the contained storage unit) are LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), GPU (Graphics Processing Unit). , It may be realized by hardware such as DSP (Digital Signal Processor), or it may be realized by the cooperation of software and hardware.

The ambient temperature acquisition unit 31 acquires information indicating the ambient temperature supplied from the ambient temperature measurement processing unit 10. The infrared energy difference acquisition unit 32 acquires information indicating an infrared energy difference supplied from the energy difference measurement processing unit 20. The target temperature acquisition unit 33 is based on the ambient temperature acquired by the ambient temperature acquisition unit 31 and the infrared energy difference acquired by the infrared energy difference acquisition unit 32, and the temperature of the measurement object P (hereinafter, the target). Temperature). Specifically, the target temperature acquisition unit 33 acquires the target temperature based on the acquired ambient temperature, the infrared energy difference, and the conversion formula for converting the energy into the temperature. The conversion formula is represented by the formula (1).

Vo = A × Tbb ^ 4-B × Ta ^ 4 + C ... (1)
Target temperature: Tbb, ambient temperature: Ta, thermopile output voltage: Vo
A, B, C: Constants including emissivity, etc.

The target temperature acquisition unit 33 supplies information indicating the acquired target temperature to the output unit 34. The output unit 34 outputs information indicating the target temperature acquired from the target temperature acquisition unit 33. The output unit 34 outputs and displays the target temperature on, for example, a liquid crystal display panel or a display device including an organic EL (ElectroLuminescence) display panel. Further, the output unit 34 is connected to, for example, a collecting device that collects the target temperature via a network, and outputs information indicating the target temperature to the collecting device.

<2. Configuration of ambient temperature measurement processing unit 10>
FIG. 2 is a diagram showing an example of the configuration of the ambient temperature measurement processing unit 10 of the present embodiment. As shown in FIG. 2, the temperature detection circuit 11 includes a resistor Ru and a diode portion Du. The resistor Ru and the diode section Du are connected in series between the voltage VD and the ground potential in the order of the resistor Ru and the diode section Du. The diode unit Du includes at least one (three in the illustrated example) diodes (diode D in the figure). The diode D is, for example, a thermal diode. The diode D is an example of a temperature detection unit. When a voltage VD is applied to the resistor Ru, a predetermined current having a magnitude corresponding to the resistance value of the resistor Ru and the voltage drop due to the forward voltage of the diode D flows through the diode section Du.

FIG. 3 is a diagram showing an example of the temperature characteristics of the diode D of the present embodiment. The vertical axis of FIG. 3 indicates the magnitude of the forward current flowing through the diode D, and the horizontal axis indicates the magnitude of the forward voltage of the diode D. In the diode section Du, the characteristics of the band gap and the forward current change according to the ambient temperature. Specifically, when the ambient temperature of the diode portion Du is low, the band gap is large and the amount of forward current is small. Further, when the ambient temperature of the diode portion Du is high, the band gap becomes small and the amount of forward current increases. Therefore, by passing a predetermined current through the diode portion Du and measuring the change in the potential difference occurring at both ends of the diode portion Du, the change in the ambient temperature can be measured as the change in the voltage. An output terminal is connected to the connection point between the resistor Ru and the diode portion Du. The temperature detection circuit 11 outputs a voltage generated between the connection point of the resistor Ru and the diode portion Du and the ground potential (that is, a potential difference generated at both ends of the diode portion Du) as a temperature signal from the output terminal.

FIG. 4 is a diagram showing an example of a range for adjusting the temperature signal of the present embodiment. The vertical axis of FIG. 4 indicates the voltage, and the horizontal axis indicates the temperature. FIG. 4 shows a waveform (shown waveform W1) showing the correspondence between the voltage of the temperature signal and the temperature change. As shown in FIG. 4, the voltage range (the shown voltage range RV1) that the temperature signal can take between 0 and 80 [° C.] is 1.39 [V] to 1.95 [V]. Here, the forward voltage of the diode D at a certain reference temperature is superimposed on the temperature signal as an offset voltage. This offset voltage is, for example, about 0.65 [V] when the ambient temperature is 0 [° C.]. As described above, three diodes D are connected in series to the diode section Du. Therefore, an offset voltage of about 1.95 [V] is superimposed on the temperature signal when the ambient temperature is 0 [° C.].

Returning to FIG. 2, the offset gain adjustment circuit 12 includes a first amplifier OP1, a second amplifier OP2, a resistor R1 that determines the amplification factor of the first amplifier OP1, and a resistor R2 that determines the amplification factor of the first amplifier OP1. A resistor R3 for determining the amplification factor of the second amplifier OP2 and a resistor R4 for determining the amplification factor of the second amplifier OP2 are provided. The first amplifier OP1 and the second amplifier OP2 are, for example, operational amplifiers. The non-inverting input terminal of the first amplifier OP1 and the output terminal of the temperature detection circuit 11 are connected. One end of the resistor R1 is connected to the inverting input terminal of the first amplifier OP1, and the other end is grounded. One end of the resistor R2 is connected to the inverting input terminal of the first amplifier OP1, and the other end is connected to the output terminal of the first amplifier OP1. The non-inverting input terminal of the second amplifier OP2 and the output terminal of the first amplifier OP1 are connected. One end of the resistor R3 is connected to the voltage VD, and the other end is connected to the inverting input terminal of the second amplifier OP2. One end of the resistor R4 is connected to the inverting input terminal of the second amplifier OP2, and the other end is connected to the output terminal of the second amplifier OP2.

With the above configuration, the inverting input terminal of the first amplifier OP1 is grounded via the resistor R1. Therefore, the potential of the inverting input terminal of the first amplifier OP1 is a potential based on the lower limit potential (that is, the ground potential) of the input voltage range. Specifically, the potential of the inverting input terminal of the first amplifier OP1 is the potential obtained by dividing the sum of the ground potential and the potential of the first amplifier OP1 by the resistor R1 and the resistor R2.
The amplification factor of the first amplifier OP1 is set so that the temperature signal after amplification does not exceed the upper limit of the input voltage range (4.1 [V] in this example). In this example, the amplification factor of the first amplifier OP1 is doubled by the resistors R1 and R2. As a result, the first amplifier OP1 amplifies the difference between the temperature signal and the ground potential twice with reference to the ground potential. In the following description, the signal obtained by amplifying the temperature signal by the first amplifier OP1 will be referred to as the first amplified signal. Here, the ground potential is an example of the first reference potential.
FIG. 4 shows a waveform (shown waveform W2) showing the correspondence between the voltage of the first amplified signal and the temperature change. As shown in FIG. 4, the voltage range that the first amplified signal can take (voltage range RV2 in the figure) between 0 and 80 [° C.] is 2.78 [V] to 3.90 [V].
If the first amplification signal does not exceed the input voltage range in the temperature range of the measurement target (0 to 80 [° C.] in this example), the amplification factor of the first amplifier OP1 is set to a value other than double. May be done.

With the above configuration, the inverting input terminal of the second amplifier OP2 is connected to the voltage VD via the resistor R3. Therefore, the potential of the inverting input terminal of the second amplifier OP2 is a potential based on the upper limit potential of the input voltage range (that is, the potential of the voltage VD). Specifically, the potential of the inverting input terminal of the second amplifier OP2 is the potential obtained by dividing the sum of the potential of the voltage VD and the potential of the second amplifier OP2 by the resistor R3 and the resistor R4.
The amplification factor of the second amplifier OP2 is set so that the temperature signal after amplification does not exceed the lower limit of the input voltage range (0 [V] in this example). In this example, the amplification factor of the second amplifier OP2 is tripled by the resistors R3 and R4. As a result, the second amplifier OP2 amplifies the difference from the first amplified signal three times with reference to the potential of the voltage VD. In the following description, the signal obtained by amplifying the first amplified signal by the second amplifier OP2 will be referred to as a second amplified signal. Here, the potential of the voltage VD is an example of the second reference potential.
FIG. 4 shows a waveform (shown waveform W3) showing the correspondence between the voltage of the second amplified signal and the temperature change. As shown in FIG. 4, the voltage range that the second amplification signal can take (voltage range RV3 in the figure) between 0 and 80 [° C.] is 0.14 [V] to 3.50 [V]. The offset gain adjustment circuit 12 outputs the second amplification signal to the A / D conversion circuit 13. The A / D conversion circuit 13 converts the second amplification signal input from the offset gain adjustment circuit 12 into a digital signal.
If the second amplification signal does not exceed the input voltage range in the temperature range of the measurement target (0 to 80 [° C.] in this example), the amplification factor of the second amplifier OP2 is set to a value other than triple. May be done.

As described above, the input voltage range of the A / D conversion circuit 13 is 0 to 4.1 [V]. The voltage range that the temperature signal output by the temperature detection circuit 11 can take is 1.39 [V] to 1.95 [V]. The voltage range that the second amplification signal output from the offset gain adjustment circuit 12 can take is 0.14 [V] to 3.50 [V].
Here, when the A / D conversion circuit 13 indicates 0 to 4.1 [V] in 256 steps from 0 to 255, the temperature signal output by the temperature detection circuit 11 has a voltage range of 1.39 [V]. ~ 1.95 [V] is indicated by the range 86-121. On the other hand, the voltage range of 0.14 [V] to 3.50 [V] that can be taken by the second amplification signal output by the offset gain adjustment circuit 12 is in the range of 9 to 218. Therefore, the offset gain adjustment circuit 12 can adjust the temperature signal output by the temperature detection circuit 11 to a wide range that matches the input voltage range of the A / D conversion circuit 13.

In the above description, the case where the first amplifier OP1 amplifies the temperature signal with reference to the ground potential and the second amplifier OP2 amplifies the first amplification signal with reference to the voltage VD has been described, but the present invention is not limited to this. .. For example, the first amplifier OP1 may be configured to amplify the temperature signal with reference to the voltage VD, and the second amplifier OP2 may be configured to amplify the first amplified signal with reference to the ground potential.

<3. Summary of embodiments>
As described above, in the temperature measuring device 1 of the present embodiment, the temperature detecting unit (in this example, the diode D) for detecting the temperature, the temperature signal indicating the ambient environmental temperature detected by the diode D, and the first. The first amplifier OP1 that amplifies the temperature signal based on the difference from the reference voltage (ground potential in this example), the first amplification signal amplified by the first amplifier OP1, and the second reference voltage (in this example). , Voltage VD), a second amplifier OP2 that amplifies the first amplified signal, and an A / D conversion circuit 13 that performs A / D conversion of the second amplified signal amplified by the second amplifier OP2. , Equipped with. Further, the ground potential is a voltage corresponding to the lower limit of the input voltage range in which the A / D conversion circuit 13 can perform A / D conversion, and the voltage VD can be A / D converted by the A / D conversion circuit 13. The voltage corresponds to the upper limit of the input voltage range.

As described above, the on-voltage of the diode D is superimposed on the temperature signal as an offset voltage. Therefore, in order to match the temperature signal with the input voltage range, the offset voltage is also amplified when simply amplified (for example, in the case of the first amplified signal). In this case, the voltage range that the temperature signal can take is biased toward a value close to the upper limit value (4.1 [V] in this example) of the input voltage range. Therefore, when the temperature signal is simply amplified, the range below the offset voltage cannot be used in the input voltage range. On the other hand, the temperature measuring device 1 of the present embodiment amplifies the temperature signal to widen the range of voltages that the temperature signal (first amplified signal) can take, and then further amplifies the voltage VD as a reference. As a result, the temperature measuring device 1 of the present embodiment can further widen the range of voltages that the temperature signal (second amplified signal) can take in the input voltage range as compared with the case where the temperature signal is simply amplified. can. Therefore, according to the temperature measuring device 1 of the present embodiment, the change in the ambient temperature can be A / D converted with high resolution.

Further, in the temperature measuring device 1 of the present embodiment, the ground potential is a voltage having the same potential as the reference voltage applied to the A / D conversion circuit 13. Further, the voltage VD is a voltage having the same potential as the reference voltage applied to the A / D conversion circuit 13, whereby the temperature measuring device 1 of the present embodiment has an input voltage range of the A / D conversion circuit 13. It is possible to perform A / D conversion with high resolution by using a simple circuit configuration without separately providing a reference potential for setting.

Further, the temperature measuring device 1 of the present embodiment has a light emitting / receiving unit (thermopile sensor 21 in this example) that receives infrared rays radiated by the temperature measurement target or emits infrared rays to the measurement target, and a thermopile sensor. The temperature is based on the infrared energy difference acquisition unit 32 that acquires the infrared energy difference from the measurement object P based on the intensity of the infrared rays received or emitted by 21 and the value output by the A / D conversion circuit 13. Based on the infrared energy difference acquired by the ambient environment temperature acquisition unit 31 that acquires the ambient environment temperature of the measuring device 1 and the infrared energy difference acquisition unit 32, and the ambient environment temperature acquired by the ambient environment temperature acquisition unit 31. The infrared energy difference acquisition unit 32 that acquires the temperature of the measurement object P and the information indicating the temperature of the measurement object P acquired by the infrared energy difference acquisition unit 32 are output as information indicating the radiation temperature of the measurement object P. It includes an output unit 34.

Here, the thermopile sensor 21 is a sensor that measures the infrared energy difference from the measurement object P. Therefore, when it is desired to grasp the target temperature of the measurement target object P, it is necessary to obtain it based on the infrared energy difference, the ambient environment temperature, and the conversion formula for converting the energy into the temperature. According to the temperature measuring device 1 of the present embodiment, the target temperature of the measurement target P can be acquired based on the ambient environment temperature and the infrared energy difference.

<4. When the temperature detector is a thermistor>
In the above description, the case where the temperature detection unit is the diode D has been described, but the present invention is not limited to this. The temperature detection unit may be, for example, a thermistor instead of the diode D. A thermistor is an element whose resistance value changes according to the ambient temperature. Therefore, by passing a predetermined current through the thermistor and measuring the change in the potential difference occurring at both ends of the thermistor, the change in the ambient temperature can be measured as the change in the voltage. Further, an offset voltage is generated in the temperature signal according to the resistance value of the thermistor at a predetermined ambient temperature (for example, 0 [° C.]). According to the ambient temperature measurement processing unit 10 of the present embodiment, the amplification factors of the first amplification signal and the second amplification signal are set according to the offset voltage of the thermistor, and the voltage that the temperature signal (second amplification signal) can take is set. The range can be further extended from the high voltage range to the constant voltage range. Therefore, according to the temperature measuring device 1 of the present embodiment, the change in the ambient temperature can be A / D converted with high resolution.

<5. When supplying an operation reference voltage to the A / D conversion circuit 13>
Further, in the above description, the input voltage range of the A / D conversion circuit 13 is from the ground potential to the voltage VD. The case has been described, but it is not limited to this. The reference voltage of the input voltage range of the A / D conversion circuit 13 may be supplied from a voltage source provided separately.
FIG. 5 is a diagram showing an example of a reference voltage of the A / D conversion circuit 13 of the present embodiment.
As shown in FIG. 5, in this example, the ambient temperature measurement processing unit 10 includes a voltage source (voltage source PW (shown)) that generates a reference voltage. The voltage source PW is, for example, a low-loss (Low Drop-Out) type linear regulator. The voltage source PW is an example of a reference voltage supply unit. The voltage source PW supplies the operation reference voltage of the A / D conversion circuit 13.

The output terminal of the voltage source PW is connected to one end of the resistor R3 instead of the voltage VD. Further, the output terminal of the voltage source PW is connected to a terminal (AD_REFH (AD reference) shown in the figure) to which the input voltage range of the A / D conversion circuit 13 is input. Here, since the voltage VD is the voltage that drives the ambient temperature measurement processing unit 10, the voltage may not be stable depending on the operation of circuits other than the A / D conversion circuit 13. When the ambient temperature measurement processing unit 10 includes the voltage source PW, the A / D conversion circuit 13 appropriately maintains the input voltage range with a stable operation reference voltage, and converts the second amplification signal (temperature signal) into a digital signal. Can be converted. Further, the second amplifier OP2 amplifies the first amplification signal into the second amplification signal based on the operation reference voltage generated by the voltage source PW. Therefore, the temperature measuring device 1 of the present embodiment matches the upper limit value of the input voltage range of the A / D conversion circuit 13 with the operating reference voltage generated by the voltage source PW, so that the surrounding circuit operates more stably. Changes in environmental temperature can be measured.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment and may be appropriately modified without departing from the spirit of the present invention. can. The configurations described in each of the above-described embodiments may be combined.

1 ... Temperature measuring device, 10 ... Ambient temperature measurement processing unit, 11 ... Temperature detection circuit, 12 ... Offset gain adjustment circuit, 13, 23 ... A / D conversion circuit, 20 ... Energy difference measurement processing unit, 21 ... Thermopile sensor, 22 ... Amplifier circuit, 30 ... Control unit, 31 ... Ambient environment temperature acquisition unit, 32 ... Infrared energy difference acquisition unit, 33 ... Target temperature acquisition unit, 34 ... Output unit, D ... Diode, Du ... Diode unit, OP1 ... No. 1 amplifier, OP2 ... 2nd amplifier, P ... measurement object, PW ... voltage source, R1, R2, R3, R4, Ru ... resistor

Claims (8)

A temperature detector that detects the temperature and
A first amplifier that amplifies the temperature signal based on the difference between the temperature signal indicating the temperature detected by the temperature detection unit and the first reference voltage.
A second amplifier that amplifies the first amplified signal based on the difference between the first amplified signal amplified by the first amplifier and the second reference voltage.
An A / D conversion circuit that performs A / D conversion of the signal amplified by the second amplifier, and
With
The first reference voltage is a voltage that is fixed at a predetermined voltage and corresponds to the lower limit of the input voltage range in which the A / D conversion circuit can perform A / D conversion.
The second reference voltage is a voltage that is fixed at a predetermined voltage and corresponds to the upper limit of the input voltage range in which the A / D conversion circuit can perform A / D conversion.
Temperature measuring device. The first reference voltage is a voltage having the same potential as the ground potential.
The temperature measuring device according to claim 1. The second reference voltage is a voltage having the same potential as the reference voltage applied to the A / D conversion circuit.
The temperature measuring device according to claim 1 or 2. The second reference voltage is a voltage supplied from a reference voltage supply unit that supplies an operation reference voltage of the A / D conversion circuit.
The temperature measuring device according to claim 1 or 2. The temperature detection unit is a diode, and the temperature detection unit is a diode.
The temperature signal includes the forward voltage of the diode at a reference temperature as an offset.
The temperature measuring device according to any one of claims 1 to 4. The temperature detection unit is a thermistor.
The temperature signal includes as an offset the voltage generated across the thermistor at a reference temperature.
The temperature measuring device according to any one of claims 1 to 4. A light receiving / receiving unit that receives infrared rays radiated by the temperature measurement target or emits infrared rays to the measurement target.
An infrared energy difference acquisition unit that acquires an infrared energy difference from the measurement target based on the intensity of the infrared rays received or emitted by the light receiving / receiving unit.
An ambient environment temperature acquisition unit that acquires the temperature of the ambient environment of the own device based on the value output by the A / D conversion circuit.
A target temperature acquisition unit that acquires the temperature of the measurement target based on the infrared energy difference acquired by the infrared energy difference acquisition unit and the temperature of the ambient environment acquired by the ambient environment temperature acquisition unit.
An output unit that outputs information indicating the temperature of the measurement target acquired by the target temperature acquisition unit, and an output unit.
The temperature measuring device according to any one of claims 1 to 6. The light receiving / receiving unit is a thermopile sensor.
The temperature measuring device according to claim 7.

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