JP2014095656A - Magnetic sensor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic sensor device which can correct, with a simple circuit configuration, lowering of an output level of a voltage signal from a bridge circuit having a magnetoresistive element due to temperature change.SOLUTION: A magnetic sensor device 3 includes a bridge circuit 20 having a magnetoresistive pattern 21, a constant voltage circuit 50 outputting a constant voltage Vref, and an amplifier circuit 51 which changes an amplification factor according to the change of an environment temperature. The amplifier circuit 51 applies an amplified voltage MRVcc obtained by amplifying the constant voltage Vref to the bridge circuit 20. When a resistance value of the magnetoresistive pattern 21 increases due to increase of the environment temperature, and the level of the voltage signal output from the bridge circuit 20 lowers, the amplifier circuit 51 increases the amplification factor to raise the amplified voltage MRVcc so as to increase the level of the voltage signal output from the bridge circuit 20. The circuit configuration is simpler compared with the case where the levels of a plurality of voltage signals from the bridge circuit 20 are corrected with a plurality of signal amplification circuits.

Description

  The present invention relates to a magnetic sensor device that detects a change in a magnetic field by a magnetoresistive element.

  There is known an encoder including a magnetic scale having tracks in which N poles and S poles are alternately arranged in the relative movement direction, and a magnetic sensor device for detecting the relative movement of the magnetic scale. The magnetic sensor device of such an encoder includes a magnetic detection circuit for detecting the A phase and the B phase on a sensor substrate arranged to face the magnetic scale.

  The magnetic detection circuit for detecting the A phase is generally a bridge circuit including two sets of two magnetoresistive elements directly connected. When a predetermined constant voltage is applied to the bridge circuit and the magnetic scale and the sensor substrate move relative to each other, the + a phase corresponding to the relative movement between the magnetic scale and the sensor substrate starts from the two midpoint positions of the bridge circuit. -A phase voltage signal is output. The magnetic detection circuit for detecting the B phase is also a bridge circuit similar to the magnetic detection circuit for detecting the A phase. When a predetermined constant voltage is applied to the bridge circuit and the magnetic scale and the sensor substrate move relative to each other, the + b phase corresponding to the relative movement between the magnetic scale and the sensor substrate starts from the two midpoint positions of the bridge circuit. -B phase voltage signal is output. The + a phase voltage signal, the -a phase voltage signal, the + b phase voltage signal, and the -b phase voltage signal are respectively input to the signal amplification circuit, amplified by the signal amplification circuit, and then the magnetic scale and the sensor substrate. Is input to an arithmetic circuit for calculating the relative movement speed. Patent Document 1 describes a magnetic sensor device that applies a voltage to a bridge circuit including a magnetoresistive element and obtains a voltage signal as an output.

Japanese Patent Application Laid-Open No. 2004-340692

  The magnetoresistive element has a temperature characteristic that the resistance value increases as the environmental temperature increases. Therefore, when the environmental temperature rises above the preset reference temperature, the amplitude of the voltage signal output from the midpoint position of the bridge circuit becomes small.

  Here, when the amplitude of the voltage signal output from the bridge circuit is reduced, there is a problem that the resolution is lowered and the accuracy of the relative movement speed calculated based on the voltage signal is lowered. For such a problem, amplification of each signal amplifier circuit to which a + a phase voltage signal, a −a phase voltage signal, a + b phase voltage signal, and a −b phase voltage signal are input in response to a rise in environmental temperature It is conceivable to increase the amplitude of each voltage signal by increasing the rate, thereby correcting the level of the voltage signal input to the arithmetic circuit.

  However, in order to change the amplification factor of each signal amplifier circuit to which the + a phase voltage signal, the -a phase voltage signal, the + b phase voltage signal, and the -b phase voltage signal are input, a plurality of signal amplifications are used. Since it is necessary to configure an amplification factor adjustment circuit that changes the amplification factor according to changes in environmental temperature in the circuit, the circuit configuration becomes complicated, resulting in an increase in the number of components and an increase in the mounting area of components on the circuit board There is.

  SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a magnetic sensor device capable of correcting with a simple circuit configuration that the level of a voltage signal output from a bridge circuit including a magnetoresistive element is lowered due to a temperature change. Is to provide.

In order to solve the above-described problems, a magnetic sensor device of the present invention includes:
A bridge circuit comprising a magnetoresistive element;
And a voltage adjustment circuit that changes a voltage applied to the bridge circuit based on a change in environmental temperature.

  According to the present invention, the voltage applied to the bridge circuit is increased when the level of the voltage signal output from the bridge circuit decreases due to an increase in the resistance value of the magnetoresistive element as the environmental temperature increases. The voltage signal level can be increased. Therefore, with a simple circuit configuration, it is possible to prevent or suppress the resolution of the magnetic sensor device from being lowered due to a change in environmental temperature.

  In the present invention, the voltage adjustment circuit includes a constant voltage circuit that outputs a constant voltage and an amplification circuit that changes an amplification factor based on a change in environmental temperature, and the amplification circuit amplifies the constant voltage. It is desirable to apply an amplified voltage amplified at a rate to the bridge circuit. In this way, the voltage applied to the bridge circuit can be arbitrarily set by setting the amplification factor of the amplifier circuit.

  In the present invention, the amplification circuit applies a reference voltage preset as the amplification voltage to the bridge circuit when the environmental temperature is a predetermined reference temperature, and the environmental temperature has risen above the reference temperature. In some cases, it is desirable to increase the amplification factor and decrease the amplification factor when the environmental temperature falls below the reference temperature. In this way, the amplified voltage becomes higher than the reference voltage when the environmental temperature rises above the reference temperature, and becomes lower than the reference voltage when the environmental temperature falls below the reference temperature. Accordingly, it is possible to suppress a decrease in the level of the voltage signal that occurs when the environmental temperature rises, and to suppress an excessive increase in the level of the voltage signal that occurs when the environmental temperature decreases.

  In the present invention, it is desirable that the amplifier circuit includes a resistance element whose resistance value varies depending on the environmental temperature. In this way, it becomes easy to change the amplification factor of the amplifier circuit in response to a change in the environmental temperature.

  In this case, if the amplifier circuit is an inverting amplifier circuit and has a negative feedback in which the output of the operational amplifier and the negative input are connected via the resistor element, the amplifier circuit can cope with a change in environmental temperature. Thus, the amplification factor of the amplifier circuit can be changed.

  In this case, if the amplifier circuit is an inverting amplifier circuit and the positive input of the operational amplifier is connected to the ground via the resistor element, the amplifier circuit is amplified in response to a change in environmental temperature. The gain of the circuit can be changed.

  In the present invention, the resistance element may be a thermistor.

  In this invention, it has a sensor board | substrate, The said magnetoresistive element is a magnetoresistive pattern formed on the said sensor board | substrate, The said magnetoresistive pattern of the said magnetoresistive element is on the said sensor board | substrate. A magnetoresistive pattern formed at a position spaced from the formed region is desirable. That is, since the magnetoresistive pattern has a temperature characteristic that the resistance value increases as the environmental temperature rises, the magnetoresistive pattern can be used as a resistance element whose resistance value changes depending on the environmental temperature. In addition, in this way, a resistance element whose resistance value changes depending on the environmental temperature is formed on the sensor substrate by using a process of forming a magnetoresistive pattern of the magnetoresistive element for detecting a change in the magnetic field. Therefore, the manufacturing cost of the magnetic sensor device can be suppressed.

  According to the present invention, since the level of the voltage signal output from the bridge circuit is adjusted by the voltage applied to the bridge circuit, it is possible to reduce the resolution of the magnetic sensor device due to a change in environmental temperature with a simple circuit configuration. It can be prevented or suppressed.

It is explanatory drawing of the linear encoder to which this invention is applied. It is a perspective view of a magnetic sensor apparatus, and explanatory drawing of an internal structure. It is the block diagram of a magnetic sensor apparatus, and the circuit diagram of an amplifier circuit. It is a graph which shows the resistance value of the thermistor accompanying the temperature change, the gain of an amplifier circuit, and the change of an amplification voltage.

  A linear encoder equipped with a magnetic sensor device will be described below as an embodiment to which the present invention is applied with reference to the drawings.

(overall structure)
FIG. 1 is an explanatory diagram showing the configuration of a linear encoder to which the present invention is applied. FIG. 2A is a perspective view of the magnetic sensor device of the linear encoder viewed from the sensor surface side, and FIG. 2B is a perspective view showing the internal structure of the magnetic sensor device. As shown in FIG. 1, the linear encoder 1 includes a magnetic scale 2 having tracks in which N poles and S poles are alternately arranged along the longitudinal direction, and a magnetic sensor device 3 that detects relative movement of the magnetic scale 2. Yes. The longitudinal direction of the magnetic scale 2 is the relative movement direction of the magnetic scale 2 and the magnetic sensor device 3.

  The magnetic sensor device 3 includes a rectangular parallelepiped sensor body 4 and a cable 5 extending from the sensor body 4. In the sensor body 4, the surface facing the magnetic scale 2 is a sensor surface 6. As shown in FIG. 2A, an opening 7 is formed in the sensor surface 6, and a sensor substrate 8 such as a silicon substrate or a ceramic grace substrate is disposed in the opening 7 in parallel with the sensor surface 6. ing. A magnetic detection circuit 9 is formed on the sensor substrate 8. The magnetic detection circuit 9 includes a magnetoresistive pattern (magnetoresistive element) 10 made of a magnetic film such as a ferromagnetic NiFe formed on a surface of the sensor substrate 8 facing the magnetic scale 2 by a semiconductor process.

  A rigid circuit board 11 is disposed in the sensor body 4 in parallel with the sensor board 8. The circuit board 11 includes a voltage adjustment circuit 12 for applying a voltage to the magnetic detection circuit 9, a signal amplification circuit 13 for amplifying a voltage signal output from the magnetic detection circuit 9 and outputting the amplified voltage signal, and the like. (See FIG. 3). The circuit board 11 and the sensor board 8 are connected via a flexible printed board 14. Power is supplied to the voltage adjustment circuit 12 from the outside via the cable 5. The amplified voltage signal output from the signal amplifier circuit 13 is input to an external arithmetic device (not shown) via the cable 5. The arithmetic device includes an A / D conversion circuit, and calculates the relative movement speed and the relative movement direction of the magnetic scale 2 and the magnetic sensor device 3 based on the amplified voltage signal.

(Circuit configuration)
FIG. 3A is a schematic block diagram showing a circuit configuration of the magnetic sensor device 3, and FIG. 3B is a circuit diagram of an amplifier circuit. As shown in FIG. 3, the magnetic sensor device 3 includes a magnetic detection circuit 9, a voltage adjustment circuit 12, and a signal amplification circuit 13.

  The magnetic detection circuit 9 includes an A-phase detection bridge circuit 20 that outputs A-phase (SIN phase), B-phase (COS phase), and Z-phase voltage signals corresponding to the relative movement of the magnetic scale 2 and the magnetic sensor device 3. A B-phase detection bridge circuit 30 and a Z-phase detection bridge circuit 40 are provided. The A-phase detection bridge circuit 20 and the B-phase detection bridge circuit 30 are formed at positions where the magnetic field of the magnetic scale 2 that moves relative to each other with a phase difference of 90 ° can be detected. The Z-phase detection bridge circuit 40 is for obtaining a reference voltage signal, and is formed at a position different from the A-phase detection bridge circuit 20 and the B-phase detection bridge circuit 30.

  The A phase detection bridge circuit 20 includes a + a phase detection pattern 23 composed of two magnetoresistive patterns 21 and 22 connected in series, and a −a phase composed of two magnetoresistive patterns 24 and 25 connected in series. A detection pattern 26 is provided. The + a phase detection pattern 23 and the -a phase detection pattern 26 are connected in parallel to form a bridge circuit. One end of the bridge circuit is connected to the power supply terminal Vcc and the other end is connected to the ground terminal GND. It is connected to the. A terminal 27 from which the + a phase is output is provided at the midpoint position of the + a phase magnetoresistive patterns 21 and 22, and the −a phase is output at the midpoint position of the −a phase magnetoresistive patterns 24 and 25. A terminal 28 is provided.

  The B-phase detection bridge circuit 30 includes a + b phase detection pattern 33 including two magnetoresistive patterns 31 and 32 connected in series, and a -b phase including two magnetoresistive patterns 34 and 35 connected in series. A detection pattern 36 is provided. The + b phase detection pattern 33 and the -b phase detection pattern 36 are connected in parallel to form a bridge circuit. One end of the bridge circuit is connected to the power supply terminal Vcc, and the other end is connected to the ground terminal GND. It is connected to the. Further, a terminal 37 for outputting the + b phase is provided at the midpoint position of the + b phase magnetoresistive patterns 31 and 32, and the −b phase is present at the midpoint position of the −b phase magnetoresistive patterns 34 and 35. An output terminal 38 is provided.

  The Z-phase detection bridge circuit 40 includes a + z phase detection pattern 43 including two magnetoresistive patterns 41 and 42 connected in series, and a −z phase including two magnetoresistance patterns 44 and 45 connected in series. A detection pattern 46 is provided. The + z phase detection pattern 43 and the -z phase detection pattern 46 are connected in parallel to form a bridge circuit. One end of the bridge circuit is connected to the power supply terminal Vcc, and the other end is connected to the ground terminal GND. It is connected to the. Further, a terminal 47 for outputting the + z phase is provided at the midpoint position of the magnetoresistive patterns 41 and 42 for the + z phase, and a −z phase is provided at the midpoint position of the magnetoresistive patterns 44 and 45 for the −z phase. Is provided.

  The voltage adjustment circuit 12 includes a constant voltage circuit 50 that receives power of a predetermined voltage and outputs power of a constant voltage Vref, and an amplifier circuit 51 that changes an amplification factor based on a change in environmental temperature. The constant voltage circuit 50 is a general circuit including, for example, a three-terminal regulator. In this example, the constant voltage circuit 50 is supplied with 5 V power and outputs a constant voltage Vref of 2.5 V. The amplifier circuit 51 supplies the amplified voltage MRVcc obtained by amplifying the constant voltage Vref from the constant voltage circuit 50 to the power supply terminal Vcc of the magnetic detection circuit 9. That is, the amplifier circuit 51 applies the amplified voltage MRVcc to each bridge circuit 20, 30, 40.

  The amplifier circuit 51 is an inverting amplifier circuit configured around an operational amplifier 52 as shown in FIG. The negative input of the operational amplifier 52 is connected to the ground terminal GND through the resistance element 53. A resistance element 55 is connected between the output terminal 54 of the amplifier circuit 51 and the output of the operational amplifier 52. On the output side of the operational amplifier 52, negative feedback is provided in which the output of the operational amplifier 52 and the negative input are connected via a thermistor 56 (resistive element). The positive input of the operational amplifier 52 and the ground terminal GND are connected via a resistance element 57. The constant voltage Vref from the constant voltage circuit 50 is supplied to the plus input of the operational amplifier 52 through the resistance element 58, and the amplified voltage MRVcc is output from the output terminal 54. Here, the amplification factor of the amplifier circuit 51 changes as the resistance value of the thermistor 56 changes. Note that the amplification factor of the amplifier circuit 51 can also be changed by replacing the resistance element 57 with another resistance element having a different resistance value.

  FIG. 4A is a graph showing a change in resistance value of the thermistor 56 accompanying a change in environmental temperature, and FIG. 4B is a graph showing a change in amplification factor of the amplifier circuit 51 accompanying a change in environmental temperature. FIG. 4C is a graph showing changes in the amplified voltage accompanying changes in the environmental temperature. As shown in FIG. 4A, the thermistor 56 has a positive temperature coefficient, and its resistance value increases as the environmental temperature increases. The temperature coefficient of the thermistor 56 is 3500 ppm / ° C.

  In this example, the reference temperature T of the environment in which the linear encoder 1 is used is set to 25 ° C., and when the environment temperature is the reference temperature T, the amplification circuit 51 outputs 3V of the reference voltage VT as the amplified voltage MRVcc. (Refer FIG.4 (c)). When the environmental temperature rises from the reference temperature T, as shown in FIG. 4A, the thermistor 56 linearly increases its resistance value as the environmental temperature rises. When the resistance value of the thermistor 56 increases, as shown in FIG. 4B, the amplification factor of the amplifier circuit 51 increases linearly. Therefore, the amplified voltage MRVcc output from the amplifier circuit 51 is equal to FIG. As shown in FIG. 4, the voltage rises linearly and becomes higher than the reference voltage VT. Therefore, an amplified voltage MRVcc larger than the reference voltage VT is applied to each bridge circuit 20, 30, 40.

  On the other hand, when the environmental temperature falls from the reference temperature T, as shown in FIG. 4A, the thermistor 56 linearly decreases the resistance value as the environmental temperature falls. When the resistance value of the thermistor 56 decreases, the amplification factor of the amplifier circuit 51 decreases linearly as shown in FIG. 4B, so that the amplified voltage MRVcc output from the amplifier circuit 51 is as shown in FIG. As shown, it falls linearly and becomes a value lower than the reference voltage VT. Therefore, an amplified voltage MRVcc smaller than the reference voltage VT is applied to each bridge circuit 20, 30, 40.

  Here, each of the magnetoresistive patterns 21, 22, 24, 25, 31, 32, 34, 35, 41, 42, 44, 45 constituting each of the bridge circuits 20, 30, 40 of the magnetic detection circuit 9 includes There is a temperature characteristic that the resistance value increases as the environmental temperature increases. For this reason, when the environmental temperature rises above the reference temperature T, the amplitude of the voltage signal output from the terminals 27, 28, 37, 38, 47, 48 at the midpoint positions of the bridge circuits 20, 30, 40 decreases. When the amplitude of the voltage signal output from the magnetic detection circuit 9 is reduced, the resolution is lowered, and the accuracy of the relative movement speed calculated based on the voltage signal is reduced.

  In order to deal with such a problem, the voltage adjustment circuit 12 causes the bridge circuit 20 to change from the voltage adjustment circuit 12 when the level of the voltage signal output from each bridge circuit 20, 30, 40 decreases as the environmental temperature increases. , 30, and 40, thereby increasing the level of the voltage signal output from each bridge circuit 20, 30, and 40. That is, when the environmental temperature changes, the voltage applied to each bridge circuit 20, 30, 40 is adjusted to correct the level of the voltage signal output from each bridge circuit 20, 30, 40. Therefore, it is possible to prevent or suppress a decrease in the resolution of the magnetic sensor device 3 due to a change in environmental temperature. When the environmental temperature falls from the reference temperature T, the voltage adjustment circuit 12 lowers the voltage applied to each bridge circuit 20, 30, 40. Therefore, an excessive increase in the level of the voltage signal output from each bridge circuit 20, 30, 40 can be suppressed.

  Next, as shown in FIG. 3A, the signal amplifying circuit 13 includes a + a phase voltage signal output from the terminals 27 and 28 of the A phase detection bridge circuit 20 of the magnetic detection circuit 9, and a -a phase signal. A + b phase output from the terminals 37 and 38 of the A phase signal amplifying circuit 61 and the B phase detection bridge circuit 30 for amplifying the voltage signal and outputting the amplified voltage signal of the + a phase and the amplified voltage signal of the -a phase. The B phase signal amplifying circuit 62 that amplifies the voltage signal and the −b phase voltage signal and outputs the + b phase amplified voltage signal and the −b phase amplified voltage signal, and the terminals 47 and 48 of the Z phase detection bridge circuit 40. A Z-phase signal amplification circuit 63 that amplifies the + z-phase voltage signal and the −z-phase voltage signal output from the output signal and outputs the + z-phase amplification voltage signal and the −z-phase amplification voltage signal. Each of the A phase signal amplifying circuit 61, the B phase signal amplifying circuit 62, and the Z phase signal amplifying circuit 63 has a general configuration. For example, the first phase amplifying voltage signal for each + phase is amplified. An operational amplifier and a second operational amplifier for amplifying each -phase voltage signal may be provided.

(Function and effect)
According to this example, the level of the voltage signal output from each bridge circuit 20, 30, 40 by changing the voltage applied by the voltage adjustment circuit 12 to each bridge circuit 20, 30, 40 (magnetic detection circuit 9). In the case where a voltage correction circuit that corrects the level of the voltage signal is provided in the signal amplification circuit 13 that amplifies each of the voltage signals of each + phase and each − phase output from each bridge circuit 20, 30, 40. As compared with the circuit configuration, the circuit configuration can be simplified. Further, even when the magnetic sensor device 3 includes a plurality of bridge circuits 20, 30, and 40 for detecting the A phase, the B phase, and the Z phase, a voltage is applied to the bridge circuits 20, 30, and 40. Since the voltage adjustment circuit 12 to be shared can be made common, the circuit configuration can be further improved as compared with the case where the levels of the voltage signals of the A phase, the B phase, and the C phase are corrected on the signal amplification circuit side. It can be simple. Therefore, an increase in the number of components can be suppressed, and an increase in the mounting area of components on the circuit board 11 can be suppressed.

  Further, in this example, since the voltage adjustment circuit 12 includes the amplification circuit 51 that amplifies the constant voltage Vref from the constant voltage circuit 50, the voltage adjustment circuit 12 is applied to the magnetic detection circuit 9 by setting the amplification factor of the amplification circuit 51. The voltage can be set arbitrarily. More specifically, the voltage applied to the magnetic detection circuit 9 can be arbitrarily set by setting the resistance value of the resistance element 53 and the resistance value of the thermistor 56 to a desired ratio.

(Other embodiments)
In the above example, the thermistor 56 is arranged between the output of the operational amplifier 52 and the negative input in the amplifier circuit 51. However, the thermistor 56 is a resistance element having a fixed resistance value, The resistance element 57 disposed therebetween may be used as the thermistor 56. Even in this case, the amplification factor of the amplifier circuit 51 can be changed in accordance with the change in the environmental temperature. That is, the amplified voltage MRVcc output from the amplifier circuit 51 is set to a value higher than the reference voltage when the environmental temperature rises above a predetermined reference temperature, and is higher than the reference voltage when the environmental temperature falls below the reference temperature. Can also be a low value.

  In the above example, the amplification circuit 51 of the voltage adjustment circuit 12 uses the thermistor 56 to change the amplification factor. However, the magnetoresistive pattern formed on the circuit board 11 or the sensor board 8 instead of the thermistor 56. Can also be used. That is, like the thermistor 56, the magnetoresistive pattern has a temperature characteristic that increases its resistance value as the environmental temperature increases. Further, each of the magnetoresistive patterns 21, 22, 24, 25, 31, 32, 34, 35, 41, 42, 44, 45 has a temperature coefficient equivalent to the temperature coefficient of the thermistor 56. Therefore, the thermistor 56 can be substituted for the magnetoresistive pattern.

  Here, a magnetoresistive pattern as a substitute for the thermistor 56 is formed on the sensor substrate 8 in the same manner as the magnetoresistive patterns 21, 22, 24, 25, 31, 32, 34, 35, 41, 42, 44, 45. Then, the magnetoresistive patterns 21, 22, 24, 25, 31, 32, 34, 35, 41, 42, 44, and 45 are formed on the sensor substrate 8 to replace the thermistor 56. A magnetoresistive pattern can be formed. Therefore, the manufacturing cost of the magnetic sensor device 3 can be suppressed. When forming a magnetoresistive pattern as a substitute for the thermistor 56 on the sensor substrate 8, it is desirable to set the formation position at a position where the magnetic field of the magnetic scale 2 is not detected. That is, the magnetoresistive pattern as an alternative to the thermistor 56 is from the formation region of the magnetic detection circuit 9 (each magnetoresistive pattern 21, 22, 24, 25, 31, 32, 34, 35, 41, 42, 44, 45). It is desirable to form at a spaced position.

DESCRIPTION OF SYMBOLS 3 ... Magnetic sensor apparatus 8 ... Sensor substrate 9 ... Magnetic detection circuit 12 ... Voltage adjustment circuit 21 ... Magnetoresistive pattern (magnetoresistive element)
20 ... A phase detection bridge circuit 30 ... B phase detection bridge circuit 40 ... Z phase detection bridge circuit 50 ... constant voltage circuit 51 ... amplifier circuit 52 ... op amp 56 ..Thermistors (resistance elements)
T ... Reference temperature VT ... Reference voltage

Claims (8)

A bridge circuit comprising a magnetoresistive element;
A magnetic sensor device comprising: a voltage adjustment circuit that changes a voltage applied to the bridge circuit based on a change in environmental temperature. In claim 1,
The voltage adjustment circuit includes a constant voltage circuit that outputs a constant voltage, and an amplification circuit that changes an amplification factor based on a change in environmental temperature,
The amplifying circuit applies an amplified voltage obtained by amplifying the constant voltage with the amplification factor to the bridge circuit. In claim 2,
The amplification circuit applies a reference voltage preset as the amplification voltage to the bridge circuit when the environmental temperature is a predetermined reference temperature, and when the environmental temperature rises above the reference temperature, the amplification circuit A magnetic sensor device characterized by increasing the rate and decreasing the amplification factor when the environmental temperature falls below the reference temperature. In claim 2 or 3,
The amplifying circuit includes a resistance element whose resistance value changes according to the environmental temperature. In claim 4,
The amplifying circuit is an inverting amplifying circuit, and includes a negative feedback in which an output of an operational amplifier and a negative input are connected via the resistance element. In claim 5,
The amplifying circuit is an inverting amplifying circuit, and a positive input of an operational amplifier is connected to the ground through the resistance element. In any one of claims 4 to 6,
The resistance element is a thermistor, and a magnetic sensor device. In any one of claims 4 to 7,
Having a sensor substrate,
The magnetoresistive element is a magnetoresistive pattern formed on the sensor substrate,
2. The magnetic sensor device according to claim 1, wherein the resistive element is a magnetoresistive pattern formed on the sensor substrate at a position separated from a region where the magnetoresistive pattern of the magnetoresistive element is formed.

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