TW201708794A - Encoder capable of reducing the impact to offset voltage caused by the temperature of a magneto-resistive element - Google Patents

Abstract

The present invention provides an encoder capable of reducing the impact to offset voltage caused by the temperature of a magneto-resistive element. When in operation, an offset adjustment part 94 sequentially record the temperatures of the offset voltage and the magnetic induction element in the memory 95. Based on the data of the memory 95, the offset adjustment part 94 calculates an approximate formula, so as to calculate the temperature of the offset voltage. When the encoder is activated the next time, the offset adjustment part 94 would immediately calculate the offset voltage based on a temperature monitoring resistive film, a detection result of a temperature calculation part 93, and the temperature characteristic.

Description

Encoder

The present invention relates to an encoder, and more particularly to an encoder having a magnetic sensor device.

In the encoder for detecting the rotation of the rotating body, for example, a magnetic sensor device in which a magnet is provided on the side of the rotating body and a magnetoresistive element (hereinafter referred to as "MR element") or a Hall element is provided on the fixed body side. In the magnetic sensor device, a magnetic induction film made of a magnetoresistive film is formed on one surface of the substrate, and the output of the bridge circuit output of the two phases (A phase and B phase) formed by the free magnetic induction film is detected, and the rotating body is detected. Angle speed or angular position, etc.

Here, in general, the resistance value of the magnetic induction film for the MR element or the Hall element used in the magnetic magnetic sensor device varies depending on the temperature. Therefore, a technique for obtaining stable detection accuracy even when the ambient temperature changes has been proposed (for example, refer to Patent Document 1). Specifically, a temperature monitoring resistive film and a heating resistive film (heater pattern) are formed on the substrate on which the magnetic induction film is formed. Then, the temperature difference or temperature change from the set temperature is monitored by the resistance value of the temperature monitoring resistive film, and the heating resistive film is supplied with power based on the monitoring result, and the magnetic induction film is heated to the set temperature. Therefore, when the ambient temperature changes, even if the resistance change due to the influence of stress or the change in resistance due to the difference in film quality is different, it is not easily affected by the ambient temperature, so even if a temperature change occurs, A stable detection accuracy can be obtained.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2014-194360

However, in the technique disclosed in Patent Document 1, temperature control is performed using the heater pattern and the MR element is maintained at a fixed temperature, but there are the following problems: (1) It takes time to reach the temperature of the MR element at the time of startup; (2) Since the temperature sensor and the magnetic induction film are disposed at different positions, the temperature inside the wafer is different, and it is easy to cause an error due to temperature distribution; or (3) in order to cope with the change of the compensation voltage over the last year, when the last action is used The compensation voltage is used as the MR component compensation voltage at startup, but the temperature characteristics are not considered here. For example, there is a problem in that the compensation is recorded in a state where the temperature is high during the operation, but since the temperature is low at the time of starting, the error is large.

The present invention has been made in view of such circumstances, and an object thereof is to provide an encoder that reduces the influence of temperature characteristics of an MR element.

The encoder of the present invention has: a magnetoresistive element formed on a substrate; a compensation voltage detecting unit that detects a compensation voltage of the magnetoresistive element; a temperature detecting unit that detects a temperature of the magnetoresistive element; and a memory unit that The compensation voltage is recorded in association with the temperature of the magnetoresistive element, and the compensation voltage determining unit calculates the compensation voltage and the magnetic quantity from data of the compensation voltage recorded in the memory unit and the temperature of the magnetoresistive element. An approximation of the relationship between the temperatures of the resistive elements, at the time of startup, the current compensation voltage is estimated based on the approximate expression of the temperature of the magnetoresistive element, and the estimated compensation voltage is used as the new compensation voltage. Therefore, it is possible to perform constant temperature control without a heating element at the time of starting, and an appropriate compensation value can be obtained even if the time until the fixed temperature is not reached. That is, it is possible to achieve a highly accurate output immediately after startup.

Further, the temperature detecting unit may be provided on the same substrate on which the magnetoresistive element is formed. Therefore, the temperature detection of the magnetoresistive element itself can be substantially realized, that is, Achieve high precision temperature detection.

Further, when the compensation voltage is recorded in the memory unit in association with the temperature of the magnetoresistive element, the temperature range may be divided for each specific range, and the compensation voltage detected in the temperature range may be averaged. Chemical. Therefore, by recording in accordance with a specific temperature range and averaging the compensation voltage, the data capacity can be suppressed. For example, it is possible to select a memory unit having a small capacity, and to record data for a long period of time, and to perform long-term correction of data.

Further, when the relationship between the measured compensation voltage and the temperature of the magnetoresistive element is different from the approximation by a certain amount or more, the compensation voltage determination unit calculates a new approximation formula based on the new data. Therefore, when the compensation voltage largely deviates due to an external cause or the like, the compensation voltage of the adaptive condition can be obtained by temporarily resetting the temperature characteristic of the approximate expression, that is, the magnetoresistive element.

Further, the temperature detecting unit may detect the temperature of the magnetoresistive element once in a communication cycle in which each of the control devices communicates with the external control unit, and the compensation voltage determining unit may calculate the approximate expression in the communication cycle. That is, the temperature calculation process is executed from the start of the angle response to the next request from the control device. As described above, by performing temperature detection for each communication cycle, the process can be simplified as compared with the non-periodical temperature detection by interrupt processing or the like. In other words, since the processing time can be sufficiently ensured, the temperature calculation processing can be surely completed.

Further, the temperature detecting unit may calculate a resistance value of the magnetoresistive element, and may detect a current temperature based on the calculated resistance value. Therefore, since the resistance value of the magnetoresistive element itself is used, it is not necessary to separately provide the temperature detecting portion. Further, since the temperature of the magnetic induction portion of the magnetoresistive element can be detected, the error due to the temperature distribution in the wafer is reduced.

Moreover, the temperature detecting unit may include a temperature monitoring resistive film formed on the substrate on which the magnetoresistive element is formed. Therefore, by using the temperature monitoring magnetic resistance film to detect the temperature of the magnetic induction portion of the magnetoresistive element, it is possible to grasp The temperature distribution within the wafer (on the substrate) can reduce errors due to temperature distribution.

According to the present invention, it is possible to provide an encoder which reduces the influence of the temperature characteristics of the magnetoresistive element on the compensation voltage.

1‧‧‧Rotary encoder

2‧‧‧Rotating body

4‧‧‧Magnetic sensing elements

4a‧‧‧Bridge circuit

4b‧‧‧Bridge circuit

10‧‧‧Magnetic sensor device

20‧‧‧ magnet

21‧‧‧Magnetized surface

31, 32‧‧‧Amplification circuit

35, 36‧‧‧Amplification circuit

40‧‧‧Substrate

40a‧‧‧One side of the substrate

41‧‧‧Magnetic Sensing Film

42‧‧‧Magnetic Sensing Film

43‧‧‧Magnetic Sensing Film

44‧‧‧Magnetic Sensing Film

45‧‧‧Magnetic sensing area (magnetic sensing part)

47‧‧‧Resistance film for temperature monitoring (temperature detection unit)

61‧‧‧1st Hall element

62‧‧‧2nd Hall element

90‧‧‧Control Department

91‧‧‧ADC Department

92‧‧‧Signal Processing Department

93‧‧‧Temperature calculation unit (temperature detection unit)

94‧‧‧Compensation Adjustment Department

95‧‧‧ memory

150‧‧‧current detection circuit (temperature detection unit)

151‧‧‧Resistance for current detection

152‧‧‧Amplifier for current detection

AL‧‧‧ Approximate straight line

D1~D4‧‧‧1st to 4th information

Dx‧‧‧Wrong data

GNDA‧‧‧ Grounding terminal

GNDB‧‧‧ Grounding terminal

GNDS‧‧‧ Grounding terminal

L‧‧‧Rotation axis direction

Sin, cos‧‧‧ sine wave signal

VccA‧‧‧ power terminal

VccB‧‧‧ power terminal

VccS‧‧‧ power terminal

Vout‧‧‧ output

Θ‧‧‧ angle

1(a) to 1(c) are views showing the principle of a magnetic sensor device and a rotary encoder according to the first embodiment.

2(a) and 2(b) are views showing an electrical connection structure of a magnetic induction film of a magnetic induction element for a magnetic sensor device and a rotary encoder according to the first embodiment.

Fig. 3 is a view showing a planar configuration of a magnetic induction element of the magnetic sensor device of the first embodiment.

Fig. 4 is a block diagram of a control unit according to the first embodiment.

Fig. 5 is a graph showing the relationship between the temperature of the magnetic induction element of the first embodiment and the compensation voltage.

Fig. 6 is a view showing an electrical connection structure of a magnetic induction film for a magnetic induction element of a magnetic sensor device and a rotary encoder according to a second embodiment.

Hereinafter, embodiments of a magnetic sensor device and a rotary encoder to which the present invention is applied will be described with reference to the drawings. Further, in the rotary encoder, when detecting the rotation of the rotating body with respect to the fixed body, a magnet may be disposed on the fixed body, a magnetic induction element may be disposed on the rotating body, and the magnetic induction element may be disposed on the fixed body and disposed on the rotating body. In the following description, the configuration of the magnet is mainly described in which the magnetic induction element is provided in the fixed body and the magnet is provided in the rotating body.

<First embodiment>

Fig. 1 is an explanatory view showing the principle of the magnetic sensor device 10 and the rotary encoder 1 according to the first embodiment of the present invention. Fig. 1(a) illustrates a signal processing system for a magnetic induction element 4 or the like. The map of the system. Fig. 1(b) is a view showing a signal output from the magnetic induction element 4. Fig. 1(c) is a view showing the relationship between the signal and the angular position (electrical angle) of the rotating body 2. 2 is a view for explaining an electrical connection structure of magnetic induction films 41 to 44 (magnetoresistive films) used in the magnetic sensor device 10 and the magnetic induction element 4 of the rotary encoder 1. Fig. 2(a) is a view showing a bridge circuit 4a composed of a magnetic induction film 43 of the +A phase and a magnetic induction film 41 of the -A phase. Fig. 2(b) is a view showing a bridge circuit 4b composed of a magnetic induction film 44 of the +B phase and a magnetic induction film 42 of the -B phase.

The rotary encoder 1 shown in Fig. 1 magnetically detects a rotation of the rotary body 2 relative to a fixed body (not shown) about an axis (around an axis of rotation) by the magnetic sensor device 10. The fixing system is fixed to a frame of the motor device or the like, and the rotating body 2 is used in a state of being coupled to a rotating output shaft of the motor device or the like. The magnet 20 is held on the side of the rotating body 2, and the magnet 20 is magnetized in the circumferential direction so that the magnetized surface 21 of each of the N pole and the S pole faces the one side in the rotation axis direction L. The magnet 20 rotates integrally with the rotating body 2 about the rotation axis.

A magnetic sensor device 10 is provided on the fixed body side, and the magnetic sensor device 10 is provided with a magnetic induction element 4 facing the magnetized surface 21 of the magnet 20 on one side in the rotation axis direction L, and is controlled by the following processing. Department 90 and so on. Further, the magnetic sensor device 10 includes the first Hall element 61 and the second Hall element 62 at a position facing the magnet 20. The second Hall element 62 is located at a position shifted by 90° from the first Hall element 61 by a mechanical angle in the circumferential direction.

The magnetic induction element 4 is provided with a magnetic field of a magnetic induction film (a phase (SIN) magnetic induction film and a B phase (COS) magnetic induction film) having a phase difference of 90° with respect to the phase of the magnet 20; Resistance element. Specifically, the magnetic induction film of the A phase includes a magnetic induction film 43 of a +A phase (SIN+) having a phase difference of 180° and detecting the movement of the rotating body 2, and a magnetic induction film 41 of the -A phase (SIN-). Similarly, the magnetic induction film of the B phase includes a magnetic induction film 44 of a +B phase (COS+) having a phase difference of 180° and detecting the movement of the rotating body 2, and a magnetic induction film 42 of a -B phase (COS-).

As shown in Fig. 2(a), one end of the magnetic induction film 43 of the +A phase and the magnetic induction film 41 of the -A phase are connected to the power supply terminal VccA for the A phase, and the ground terminal GNDA for the other end and the phase A is used. connection. An output terminal +A of the output +A phase is provided at a midpoint of the magnetic induction film 43 of the +A phase. An output-A phase output terminal -A is provided at a midpoint of the magnetic induction film 41 of the -A phase.

As shown in Fig. 2(b), the magnetic induction film 44 of the +B phase and the magnetic induction film 42 of the -B phase are also used in the same manner as the magnetic induction film 44 of the +A phase and the magnetic induction film 41 of the -A phase. The power supply terminal VccB is connected, and the other end is connected to the ground terminal GNDB for the B phase. An output terminal +B of the output +B phase is provided at a midpoint of the magnetic induction film 44 of the +B phase, and an output terminal -B of the output -B phase is provided at a position of the magnetic induction film 42 of the -B phase.

In addition, for convenience, each of the power supply terminal VccA for the A phase and the power supply terminal VccB for the B phase is described in FIG. 2, but the power supply terminal VccA for the A phase and the power supply terminal VccB for the B phase may be shared. . Further, for convenience, each of the ground terminal GNDA for the A phase and the ground terminal GNDB for the B phase is described in FIG. 2, but the ground terminal GNDA for the A phase and the ground terminal GNDB for the B phase may be shared.

As shown in Fig. 1(a), the magnetic induction element 4 of such a configuration is disposed at a position overlapping the magnetization boundary portion of the magnet 20 in the rotation axis direction L. Therefore, the magnetic induction films 41 to 44 of the magnetic induction element 4 can detect the rotating magnetic field that changes in the in-plane direction of the magnetized surface 21 under the magnetic field intensity above the saturation sensitivity region of the resistance values of the magnetic induction films 41 to 44. In other words, in the portion of the magnetization boundary line, a rotating magnetic field which changes in the direction of the inner direction of the magnetic field intensity above the saturation sensitivity region of the resistance values of the respective magnetic induction films 41 to 44 is generated.

Here, the saturation sensitivity region generally means that the resistance value change amount k can be approximated to the magnetic field strength H by "k" The area outside the area indicated by H2". Further, the principle of detecting the direction of the rotating magnetic field (rotation of the magnetic vector) in the magnetic field intensity above the saturation sensitivity region is as follows: when the magnetic field strength of the magnetic resistance film 41 to 44 is applied, when the magnetic field strength of the resistance value is applied There is a relationship between the angle θ between the magnetic field and the current direction and the resistance value R of the magnetic induction films 41 to 44.

R=R ₀ -k×sin2θ

R ₀ : no resistance value in the magnetic field

k: amount of change in resistance value (constant when saturated sensitivity region or more)

When the rotating magnetic field is detected based on such a principle, when the angle θ changes, the resistance value R changes along the sine wave, so that the A-phase output and the B-phase output with high waveform quality can be obtained.

As shown in FIG. 1(a), a control unit 90 is connected to the magnetic sensor device 10. Specifically, the magnetic induction element 4 is connected to the control unit 90 via the amplifier circuits 31 and 32, and the control unit 90 is connected to the first Hall element 61 and the second Hall element 62 via the amplifier circuits 35 and 36.

The control unit 90 includes a CPU (arithmetic circuit) that performs interpolation processing or various arithmetic processing on the sine wave signals sin and cos output from the magnetic sensor device 10, based on the magnetic induction element 4, the first Hall element 61, and The output of the second Hall element 62 determines the rotational angle position of the rotating body 2 with respect to the fixed body.

More specifically, in the rotary encoder 1, when the rotary body 2 rotates once, the sine wave signals sin and cos shown in FIG. 1(b) are outputted from the magnetic induction element 4 (magnetoresistive element) for two cycles. The control unit 90 obtains the Lissajous figure shown in Fig. 1(c) based on the sine wave signals sin and cos amplified by the amplifier circuits 31 and 32, and further obtains θ=tan-1 based on the sine wave signals sin and cos (sin). /cos), calculate the angular position θ of the rotary output shaft.

Further, in the present embodiment, the first Hall element 61 and the second Hall element 62 are disposed at positions shifted by 90 from the center of the magnet 20. Therefore, by the combination of the outputs of the first Hall element 61 and the second Hall element 62, it can be seen which of the sine wave signals sin and cos the current position is. As a result, the rotary encoder 1 can generate the absolute angular position information of the rotating body 2 based on the detection result of the magnetic induction element 4, the detection result of the first Hall element 61, and the detection result of the second Hall element 62, and can perform absolute action.

FIG. 3 is a view for explaining the magnetic induction element 4 of the magnetic sensor device 10. Here, the planar configuration of the magnetic induction element 4 is exemplified, and for the sake of convenience, the temperature monitoring resistive film 47 is marked with a diagonal line toward the lower right.

As shown, in the magnetic sensor device 10, the magnetic sensing element 4 is provided with a substrate 40 and a shape The magnetic induction films 41 to 44 are formed on one surface 40a of the substrate 40. The magnetic induction films 41 to 44 constitute a circular magnetic induction region 45 by a portion extending in a mutually folded manner at the center of the substrate 40. The substrate 40 is, for example, a crucible substrate having a quadrangular planar shape.

The magnetic induction films 41 to 44 integrally extend the wiring portion, and the power supply terminal VccA for the A phase, the ground terminal GNDA for the A phase, and the output terminal +A, -A for the +A phase output are provided at the end portion of the wiring portion. Output terminal for phase output - power supply terminal VCCB for phase B, ground terminal GNDB for phase B, output terminal +B for +B phase output, and output terminal -B for -B phase output.

Further, a temperature monitoring resistive film 47 is formed on one surface 40a of the substrate 40. The temperature monitoring resistive film 47 is provided in the lower right area of the substrate 40 as shown, and is close to the magnetic sensing region 45. The temperature monitoring resistive film 47 has a planar shape that is folded back and extended a plurality of times. Here, the temperature monitoring resistive film 47 partially overlaps the wiring portion of the magnetic induction film 44 in the plan view, but the temperature monitoring resistive film 47 is formed in a region deviated from the magnetic induction region 45 in the in-plane direction of the substrate 40. Without coincident with the magnetic sensing region 45.

The temperature monitoring resistive film 47 is a conductive film that does not exhibit a magnetoresistance effect. Therefore, even if the magnetic flux density of the temperature monitoring resistive film 47 changes, the temperature can be accurately monitored. Further, since the temperature monitoring resistive film 47 is formed adjacent to the magnetic induction elements 4 (magnetic induction films 41 to 44) on the same substrate, the temperature of the magnetic induction element 4 can be detected with high precision and high sensitivity.

A power supply terminal VccS for temperature monitoring is formed at one end of the temperature monitoring resistive film 47. Further, the other end portion of the temperature monitoring resistive film 47 is connected to the ground terminal GNDB for the B phase. Therefore, the ground terminal GNDB for the B phase can also be used as the ground terminal GNDS of the temperature monitoring resistive film 47.

FIG. 4 is a block diagram of the control unit 90. The control unit 90 includes an ADC unit 91, a signal processing unit 92, a temperature calculation unit 93, a compensation adjustment unit 94, and a memory 95.

The ADC section 91 classifies the output from the magnetic sensor device 10 by A/D conversion. The ratio signal is converted to a digital signal. The signal processing unit 92 detects the rotational angle position, the rotational speed, and the like of the magnet 20 based on the A/D converted signal.

The temperature calculation unit 93 performs temperature calculation processing on the magnetic induction element 4, and detects a temperature difference and a temperature change from the set temperature by the resistance value of the temperature monitoring resistor film 47.

As the timing of the temperature detection, for example, each communication cycle that communicates with a specific control device (upper device) that controls the rotary encoder 1 is detected once, and temperature calculation processing is performed in the communication cycle. That is, the temperature calculation process is executed from the start of the angle response until the next request from the control device is received. The temperature calculation process ends with a number of 10 μs, and the period has a period longer than 10 μs, so the processing is surely ended in the communication cycle. By performing temperature detection for each communication cycle, the process can be simplified as compared with non-periodical temperature detection by interrupt processing or the like.

The compensation adjustment unit 94 sequentially records the compensation voltage obtained based on the output of the magnetic induction element 4 in the memory 95 in association with the temperature of the element detected by the temperature calculation unit 93. Further, the compensation adjustment unit 94 calculates the temperature characteristic of the compensation voltage based on the data recorded in the memory 95 at the time of startup, and calculates the compensation voltage at the time of startup based on the current temperature. Furthermore, when the amount of writing of the memory 95 is full, the oldest data is overwritten with the latest information.

Fig. 5 is a graph showing the relationship between the temperature of the magnetic induction element 4 and the compensation voltage. The adjustment process of the compensation voltage will be described with reference to this chart. The horizontal axis represents the temperature of the magnetic induction element 4 (the detection result detected by the temperature monitoring resistive film 47 and the temperature calculating unit 93). The vertical axis represents the compensation voltage of the magnetic induction element 4.

As described above, during the operation of the rotary encoder 1, the compensation adjustment unit 94 sequentially records the compensation voltage in the memory 95 in pairs with the temperature of the magnetic induction element 4. For example, in Fig. 5, the first to fourth data D1 to D4 are shown on the graph.

The compensation adjustment unit 94 calculates an approximate expression (here, an approximate straight line AL) based on the first to fourth data D1 to D4, and calculates the temperature characteristic of the compensation voltage. As temperature specific, such as The intercept and slope of the approximate straight line AL are obtained.

Then, when the rotary encoder 1 is started, the compensation adjustment unit 94 calculates the compensation voltage from the start of the self-starting based on the temperature characteristics based on the detection results of the temperature monitoring resistor film 47 and the temperature calculation unit 93. As a result, the compensation voltage can be appropriately calculated immediately after the start, and the output error of the rotary encoder 1, that is, the angular error can be reduced. Further, even if the year-to-year variation of the compensation voltage or the year-to-year variation of the compensation voltage temperature characteristic occurs, it can be corrected in order. In other words, the compensation adjustment unit 94 learns the compensation voltage temperature characteristic, and can calculate the compensation voltage immediately after startup with high accuracy and high sensitivity.

Further, when the compensation voltage and the temperature of the magnetic induction element 4 are recorded in pairs in the memory 95, the temperature range may be divided according to a specific range, and the compensation voltage detected in the temperature range may be averaged and stored. Since the required capacity can be suppressed, it is effective when the capacity of the usable memory 95 is limited. Moreover, from another point of view, it is possible to extend the period until the data is overwritten, and it is possible to use long-term data.

Further, when it is detected that the compensation voltage and the data indicated by the temperature of the magnetic induction element 4 deviate from the approximate straight line AL by a certain value or more, the compensation adjustment unit 94 determines that an error has occurred and resets the existing temperature characteristic. That is, the compensation adjustment unit 94 performs initialization of learning.

For example, as shown in the figure, the error data D _error (Dx) is a value lower than the approximate line AL by ΔV. In this case, there is a possibility that the magnetic induction element 4 has a defect such as a change in the element, and the output characteristic of the magnetic induction element 4 changes. Therefore, in this case, the compensation adjustment unit 94 discards the existing data, records the new data acquired thereafter, and uses it. Further, when the initialization of the learning is frequently performed, the compensation adjustment unit 94 determines that the rotary encoder 1 has failed, and notifies the intention by a specific warning mechanism (display means or the like).

<Second embodiment>

In the present embodiment, the temperature of the magnetic induction element itself is directly detected based on the current flowing through the magnetic induction element (MR element), and the compensation voltage of the temperature is calculated. Furthermore, the configuration other than the temperature measurement technique of the magnetic induction element (MR element) can be configured by the first embodiment. The features and functions of the present embodiment are described in the same manner, and the same components and functions are denoted by the same reference numerals, and their description will be appropriately omitted.

FIG. 6 is a view for explaining an electrical connection structure of the magnetic induction films 41 to 44 (magnetoresistive films) used in the magnetic sensor device 10 and the magnetic induction element 4 of the rotary encoder 1. Here, the bridge circuit 4a on the A-phase side has a configuration in which the current detecting circuit 150 is added to the configuration of FIG. 2(a) of the first embodiment.

As shown in the figure, in the middle of the path of the power supply terminal VccA for the A phase and the bridge circuit 4a on the A phase side, that is, the current detecting circuit 150 is provided on the high side. Furthermore, the configuration of the current detecting circuit 150 shown here is a basic circuit configuration for current detection for ease of explanation. Actually, a dedicated current detecting IC is usually used, and the same applies to the present embodiment. Further, it is not limited to the high side, and current detection can be performed on the low side.

The current detecting circuit 150 includes a current detecting resistor 151 and a current detecting amplifier 152. The current detecting resistor 151 is inserted in series in the middle of the path of the power supply terminal VccA for the A phase and the bridge circuit 4a for the A phase. Here, when the resistance values of the magnetic induction films 41 and 43 are 500 Ω to 1000 Ω, by setting the resistance value of the current detecting resistor 151 to several tens of Ω, current detection can be performed without substantially reducing the S/N ratio. .

Both ends of the current detecting resistor 151 are connected to two inputs (+/-) of the current detecting amplifier 152. Further, an output (Vout) of the current detecting amplifier 152 is connected to the control unit 90.

Next, the temperature detection processing will be described. The temperature detection process is realized by the same configuration as that of the control unit 90 of Fig. 4 . The temperature coefficient of resistance α of the magnetic induction element 4 and the compensation value (resistance value R _{OMR at} a certain temperature) are recorded in the memory 95. The temperature calculation unit 93 calculates the resistance value R _{MR of the} magnetic induction element 4 based on the current flowing through the magnetic induction element 4 and the applied voltage, and refers to the memory 95 to calculate the temperature t of the current magnetic induction element 4. The temperature t of the current magnetic induction element 4 is derived according to the following relationship.

R _MR =R _OMR +α(tt ₀ )

α : temperature coefficient of resistance of the magnetic induction element 4

R _OMR : resistance value of the magnetic induction element 4 at a specific temperature t ₀

Here, the resistance values of the respective elements (magnetic induction films 41, 43) constituting the resistance bridge in the magnetic induction element 4 vary depending on the direction in which the external magnetic flux is applied, but are constituted by the bridge shown in Fig. 3 (magnetic induction film) 41, 43) The configuration is substantially fixed throughout the resistor. The same applies to the elements on the B-phase side (magnetic induction films 42, 44). The compensation adjustment unit 94 obtains the compensation voltage of the magnetic induction element 4 using the obtained temperature. Furthermore, the temperature characteristics of the compensation voltage are recorded in advance in the memory 95.

In addition, by providing the current detecting circuit 150 and providing the temperature monitoring resistive film 47 of the first embodiment, it is possible to grasp the temperature distribution in the magnetic sensor device 10, that is, the temperature distribution on the substrate 40, and it is possible to accurately Calculate the temperature condition. Further, the CPU mounted on the rotary encoder 1 has a built-in temperature sensor, but the temperature sensor output is not calibrated. Therefore, the current detecting circuit 150 can also be used as a temperature sensor for internal calibration.

The present invention has been described above based on the embodiments, but it should be understood by those skilled in the art that the embodiments are exemplified, and various combinations of the constituent elements and the like can be implemented, and the modifications are also within the scope of the present invention. Inside.

90‧‧‧Control Department

91‧‧‧ADC Department

92‧‧‧Signal Processing Department

93‧‧‧Temperature calculation unit (temperature detection unit)

94‧‧‧Compensation Adjustment Department

95‧‧‧ memory

Claims (10)

An encoder comprising: a magnetoresistive element formed on a substrate; a compensation voltage detecting unit that detects a compensation voltage of the magnetoresistive element; a temperature detecting unit that detects a temperature of the magnetoresistive element; and a memory unit; And recording the compensation voltage in association with the temperature of the magnetoresistive element; and the compensation voltage determining unit calculates the compensation voltage by using the data of the compensation voltage recorded in the memory unit and the temperature of the magnetoresistive element In the approximate expression of the relationship between the temperatures of the magnetoresistive elements, the current compensation voltage is estimated based on the approximate expression of the temperature of the magnetoresistive element at the start, and the estimated compensation voltage is used as the new compensation voltage. An encoder according to claim 1, wherein said temperature detecting portion is provided on said same substrate on which said magnetoresistive element is formed. The encoder of claim 2, wherein when the compensation voltage is recorded in the memory unit in association with the temperature of the magnetoresistive element, the temperature range is divided according to each specific range, and is detected within the temperature range. The compensation voltage is averaged out. The encoder of claim 3, wherein the compensation voltage determination unit calculates a new approximation based on the new data when the relationship between the measured compensation voltage and the temperature of the magnetoresistive element deviates from the approximation by a certain amount or more. The encoder of claim 4, wherein the temperature detecting unit detects the temperature of the magnetoresistive element once in each communication cycle in communication with an external control device, and the compensation voltage determining unit calculates the approximation in the communication cycle. formula. The encoder according to any one of claims 1 to 5, wherein the temperature detecting unit calculates The resistance value of the magnetoresistive element is measured, and the current temperature is detected based on the calculated resistance value. The encoder according to any one of claims 1 to 5, wherein the temperature detecting unit includes a temperature monitoring resistive film formed on the substrate on which the magnetoresistive element is formed. The encoder of claim 1, wherein when the compensation voltage is associated with the temperature of the magnetoresistive element and recorded in the memory portion, the temperature range is divided according to each specific range, and is detected within the temperature range. The compensation voltage is averaged out. The encoder of claim 1, wherein the compensation voltage determining unit calculates a new approximation based on the new data when the relationship between the measured compensation voltage and the temperature of the magnetoresistive element is different from the approximation by a certain amount or more . An encoder according to claim 1, wherein said temperature detecting unit detects a temperature of said magnetoresistive element once in each communication cycle in communication with an external control device, and said compensation voltage determining unit calculates said approximation in said communication cycle. formula.