JPH03218413A - Rotational angle sensor - Google Patents

Abstract

PURPOSE:To suppress output fluctuation caused by the change of a surrounding temperature by providing a temperature compensating resistor element composed of the same material as the ferromagnetic resistor element of a detecting element. CONSTITUTION:On an element substrate 11, a magnetic sensor 10 forms the patterns of a detecting element 12 and a temperature compensating resistor element 13 by the magnetic resistor element of ferromagnetic alloy and the sensor 10 is mounted on a circuit board 30. Then, a magnet member 20 is arranged at a prescribed interval to the sensor 10 and the board 30. When a shaft 2 is rotated and a permanent magnet 21 is rotated around the sensor 10, the change of magnetic flux is generated to the detecting element 12 and the resistance value of the magnetic resistor element constituting a bridge circuit is changed by a magnetic resistance effect. Since a constant current flows from a current control circuit to this element 12, the rotational angle of the shaft 2 is detected as the output of the bridge circuit corresponding to the change of the resistance value. When the surrounding temperature of the sensor 10 is changed and a resistance value of the magnetic resistor element of the element 12 is changed, the element 13 also shows the similar change of the resistance value and the supplying current of the current control circuit is controlled in response to this change. Then, the output fluctuation of the element 12 can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rotation angle sensor for detecting the rotation angle of a shaft, and more particularly to a non-contact rotation angle sensor using a magnetoresistive element.

[Prior Art] Recently, the use of magnetic sensors has been attracting attention due to the need to construct a non-contact mechanism or to reduce the inertia loss of a shaft as a sensor for detecting rotational angle or rotational position. This magnetic sensor uses a magnetoresistive element,
The plate surface of the element is arranged to face, for example, a permanent magnet attached to the tip of the shaft.

As the above-mentioned magnetoresistive element, a ferromagnetic magnetoresistive element is known that utilizes the property that the resistance of a ferromagnetic substance in a magnetic field changes anisotropically depending on the angle formed between the magnetization direction and the current direction. This property is called the anisotropic magnetoresistive effect, and is distinguished from the negative magnetoresistive effect due to the magnitude of the magnetic field. That is, in a normal ferromagnetic material, due to the anisotropic magnetoresistance effect, the resistance is maximum when the current and the magnetization direction are parallel to each other, and minimum when the current and magnetization direction are perpendicular to each other. In order to take advantage of this effect, a ferromagnetic magnetoresistive element is constructed by attaching a thin film of ferromagnetic metal to the surface of the substrate in the form of a broken line.
As described in Japanese Patent Application No. 302, a rotational position detection device is known in which a ferromagnetic magnetoresistive element is provided on either an end face of a shaft or a position facing the end face, and a permanent magnet is provided on the other end.

By the way, when the above-mentioned ferromagnetic magnetoresistive element is driven by a constant current power supply or a constant voltage power supply, since the ferromagnetic magnetoresistive element has a positive temperature coefficient, the output decreases approximately linearly as the temperature rises. The temperature coefficient of the output is smaller when driven by the former. As described above, the output characteristics of magnetoresistive elements including the above-mentioned ferromagnetic magnetoresistive elements vary depending on temperature changes, and temperature compensation is required when the ambient temperature, that is, the external environment temperature changes. For this reason, electrical circuit processing is generally performed to compensate the output according to temperature changes in the external environment, and various processing is performed. For example, in Japanese Unexamined Patent Publication No. 63-42403, a series circuit of a temperature compensation diode and a resistance element is installed between a constant current circuit that supplies a constant current to a bridge of a magnetoresistive element and a constant voltage circuit that drives it. A temperature compensation circuit has been proposed in which the intermediate connection point is connected to a constant current circuit.

[Problem 8 to be solved by the invention] However, in the temperature compensation circuit described in the above publication,
An element different from the magnetoresistive element for rotation detection is added for temperature compensation, and both elements exhibit their own unique temperature characteristics.

In this way, if the temperature characteristics of the detection magnetoresistive element and the temperature compensation element differ, adjustment between the two becomes necessary, and it is extremely difficult to perform stable temperature compensation over the entire temperature range during measurement. be. Moreover, it is necessary to individually select and adjust elements depending on the situation in response to temperature changes in the external environment in various situations, which increases costs.

On the other hand, if the temperature compensation element is also a ferromagnetic magnetoresistive element, and the detection element and temperature compensation element are made of the same material, both will show the same change in resistance value. Therefore, fluctuations in the output of the detection element due to temperature changes in the external environment can be suppressed. However, JP-A-62-2
As described in Japanese Patent Application No. 37302, the detection element has a pattern shape in which a pair of horizontal blocks centered on an element whose longitudinal direction is horizontal and a pair of vertical blocks centered on an element whose longitudinal direction is vertical are connected alternately. In the case where the blocks are constructed using ferromagnetic magnetoresistive elements and the resistance values differ between these blocks, it may not be possible to sufficiently suppress output fluctuations due to changes in external environmental temperature depending on the rotation angle of the shaft. For example, when the rotation angle of the shaft is 90 degrees, large output fluctuations occur due to changes in the external environmental temperature.

Therefore, the present invention provides a rotation angle sensor that easily and reliably suppresses output fluctuations due to temperature changes in the external environment, regardless of the rotation angle of the shaft, even when the resistance values of the ferromagnetic magnetoresistive elements of each block constituting the detection element are different. The purpose is to suppress the detection accuracy and ensure stable detection accuracy.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a pair of horizontal blocks centered on an element whose longitudinal direction is horizontal, and a pair of vertical blocks centered on an element whose longitudinal direction is vertical. A detection element comprising a pattern-shaped ferromagnetic magnetoresistive element connected alternately to the plate surface of a substrate, and a bridge circuit configured by the pair of horizontal blocks and the pair of vertical blocks;
A rotation angle sensor comprising a current control circuit connected to the detection element and supplying a constant current, and configured to detect the rotation angle of the shaft by a change in magnetic flux accompanying rotation of the shaft relative to the detection element. A ferromagnetic magnetoresistive element made of the same material as the ferromagnetic magnetoresistive element, with a horizontal block centered on an element whose longitudinal direction is horizontal, and a horizontal block whose longitudinal direction is vertical and whose resistance value is different from that of the horizontal block. Temperature compensation comprising a pattern-shaped ferromagnetic magnetoresistive element connected to a vertical block centered on the element, arranged adjacent to the detection element, attached to the plate surface of the substrate, and connected to the current control circuit. A resistive element is provided, and the current supplied to the current control circuit is adjusted in accordance with a change in resistance value of the temperature-compensating resistive element due to a change in ambient temperature.

Note that the current control circuit connects the detection element between the output terminal and the inverting input terminal of the operational amplifier, and
A resistor whose one end is connected to a power supply is connected to the inverting input terminal of the operational amplifier, and one end of the temperature compensation resistance element is connected to the power supply and the other end is connected to the non-inverting input terminal of the operational amplifier. The temperature compensating resistive element can be grounded and configured such that the temperature compensating resistive element is a dividing resistor that sets a reference voltage for the operational amplifier.

[Function] In the rotation angle sensor configured as described above, magnetic flux changes occur in the detection element as the shaft rotates, and due to the magnetoresistive effect, the resistance value of the ferromagnetic magnetoresistive element of each block that makes up the bridge circuit changes. changes. Since a constant current is supplied to this detection element by a current control circuit, the rotation angle of the shaft is detected as an output of the bridge circuit in accordance with the change in the resistance value.

When the resistance value of the ferromagnetic magnetoresistive element in each block of the detection element changes due to a change in the ambient temperature of the rotation angle sensor, the temperature compensation resistance element placed adjacent to the detection element also changes due to the ferromagnetic magnetism of the detection element. Since it is composed of a ferromagnetic magnetoresistive element made of the same material as the resistance element, it exhibits a similar change in resistance value. Moreover, since the resistance value of at least one of the horizontal block and the vertical block constituting the temperature compensation resistance element is adjusted and the resistance values of both blocks are set to different values, the difference in the resistance value of both blocks is Accordingly, the temperature compensation resistance value shows a predetermined relationship with the rotation angle of the shaft.

Therefore, the supply current of the current control circuit is adjusted according to the change in the temperature compensation resistance value, and the output fluctuation of the detection element due to the change in the resistance value of the ferromagnetic magnetoresistive element due to the change in the ambient temperature is suppressed. . In particular, even if the resistance values of the blocks that make up the bridge circuit are different, the resistance value of the temperature compensation resistance element has a predetermined relationship with the rotation angle of the shaft. Fluctuations in the output of the detection element can be suppressed without being affected.

[Embodiments] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

1 to 3 show an embodiment of the rotation angle sensor of the present invention. As shown in FIG. 2, a magnetic sensor 10 is mounted on a circuit board 30, and a magnet is placed opposite to the magnetic sensor 10. A shaft 2 with a member 20 is arranged.

As shown in FIG. 1, the magnetic sensor 10 has a thin film of a magnetoresistive element made of a ferromagnetic alloy such as a Ni-Co alloy attached to an element substrate 11 made of glass or the like. A pattern is formed. The ferromagnetic magnetoresistive element is formed by integrated circuit manufacturing techniques such as vapor deposition and photoetching.

The ferromagnetic magnetoresistive element (hereinafter simply referred to as magnetoresistive element) that constitutes the detection element 12 and the temperature compensation resistance element 13 is as follows:
In order to achieve high resistance, a strip-shaped thin film ferromagnetic alloy is bent to form a continuous U-shaped pattern, and is also divided into a plurality of blocks in consideration of the magnetoresistive effect. That is, the detection element 12 consists of a pair of horizontal blocks of magnetoresistive elements Ra, Rh centered on an element whose longitudinal direction is horizontal, and a pair of vertical blocks of magnetoresistive elements Rc.Rc, centered on an element whose longitudinal direction is vertical. Rd is formed in a pattern shape consisting of four blocks connected alternately. A terminal 12 is connected to the connection point between each block of the magnetoresistive elements Ra to Rd.
A to 12d are formed, and a bridge circuit is constituted by these magnetoresistive elements Ra to Rd. That is, the terminals 12a and 12b are so-called IT flow terminals, and are connected to a T flow control circuit 41 as shown in FIG. 3, which will be described later.

The terminals 12c and 12d are so-called voltage terminals, and detection signals are output from these terminals.

In addition, the temperature-compensated resistance element 13 has a vertical block of magnetoresistive elements Rla centered on an element whose longitudinal direction is perpendicular, and a horizontal block of magnetoresistive elements Rib centered on an element whose longitudinal direction is horizontal, which are orthogonal to each other. It is formed into a pattern shape that is connected in such a way that the At both ends are terminals 13a, 1
3b is formed, and as shown in FIG.
is connected to a constant voltage power supply Vc (hereinafter simply referred to as power supply Vc), and the terminal 13b is grounded via a resistor R2.

In this embodiment, a temperature compensation resistance element 1 is used as described later.
3 constitutes a part of the current control circuit 41. Although the temperature compensation resistance element 13 and the detection element 12 in this embodiment are attached on one element substrate 11, they may be formed separately and placed close to each other.

The terminals 12a to 12d, 13a and 13b are the second
A plurality of leads 31 formed on the circuit board 30 shown in the figure
electrically connected to. On the surface of the circuit board 30 opposite to the surface on which the magnetic sensor 10 is mounted, circuit elements constituting a detection circuit, which will be described later, are mounted. The detection element 12 and the temperature compensation resistance element 13 are electrically connected via.

Then, as shown in FIG. 2, the magnet member 20 is placed at a predetermined distance from the magnetic sensor 10 and the circuit board 30. The magnet member 20 consists of a permanent magnet 21 and a pair of abbreviated magnetic arms 22 and 23 joined to both sides of the permanent magnet. It is fixed to the magnet 21. The magnetic arm portions 22 and 23 have a tip portion 22a of each bent portion. Each of the magnets 23a is bonded to the side surface of the permanent magnet 21 by adhesive or the like so that the engaging surfaces thereof face each other, and a gap is formed between the end surfaces of the tip portions 22a and 23a. Thus, the permanent magnet 21 attaches an N pole and an S8 to the tips 22a and 23a of the magnetic arms 22 and 23, respectively.
i is formed, and a magnetic field of parallel magnetic flux with uniform magnetic flux density is formed between the two. As a result, the magnetic sensor 10 is in a uniform parallel magnetic field formed between the tips 22a and 23a, and the plate surface of the element substrate 11 is located parallel to this.
Therefore, a uniform magnetic flux parallel to the plate surface is applied to the magnetic resistance elements constituting the detection element 12 and the temperature compensation resistance element 13.

When the permanent magnet 21 rotates around the magnetic sensor 10 due to the rotation of the shaft 2, the tip portion 22a. The magnetic field between the magnetoresistive elements 23a rotates, and the angle between the magnetization direction and the current direction with respect to the magnetoresistive element changes.

In this case, the resistance value of the magnetoresistive element is maximum when the current supplied to the magnetoresistive element and the direction of magnetization due to the magnetic field between the tips 22a and 23a are parallel to each other, and is minimum when they are perpendicular to each other. Therefore, the terminal 12c of the detection element 12,
The output of the shaft 12d is a substantially sinusoidal wave, and an output characteristic that is substantially linear with respect to the rotation angle of the shaft 2 is obtained except for the vicinity of the maximum and minimum values.

On the other hand, in the temperature compensation resistance element 13, the patterns of the magnetoresistive elements Rla and Rtb in two orthogonal blocks are formed parallel to the patterns of the magnetoresistive elements Re and Rb, respectively, as shown in FIG. There is. These magnetoresistive elements Rla and Rlb are provided with leads FLI and L2, respectively, which connect the elements constituting the pattern, and the resistance value can be adjusted by cutting these leads Ll and L2. ing. That is, the magnetoresistive element R1a. Leads Ll and L2 connecting the elements of each pattern are cut by a laser trimming device so that R1b each exhibits a predetermined resistance value. In this example, the magnetoresistive element R when no magnetic field is applied is
The resistance value of the magnetoresistive element Rib is smaller than the resistance value of la, and the combined resistance of both is larger when the rotation angle of the shaft 2, that is, when the angle θ is 90° than when the angle θ is 0°. It is set as follows.

FIG. 3 shows an embodiment of a detection circuit connected to the magnetic sensor 10. The bridge circuit 40 includes four blocks of magnetoresistive elements Ra that constitute the detection element l2 shown in FIG.
Consisting of Rd to Rd. Then, as described above, the terminals 12a,
A current control circuit 4l is connected to 12b. The current control circuit 41 includes a temperature compensation resistance element 13, and has a terminal 13a.
is connected to the power supply Vc, and the terminal 13b is grounded via a resistor R2. The temperature compensation resistance element 13 made up of magnetoresistive elements Rla and Rib constitutes a part of the current control circuit 41. Terminals 12c and 12d are output terminals of the bridge circuit 40, and are connected to a differential amplifier circuit 42, respectively. Then, the output of the differential amplifier circuit 42 is output as a rotation angle signal from the output terminal (1).

The current control circuit 41 has an operational amplifier (hereinafter referred to as an operational amplifier) OP1, and a bridge circuit 40 is connected to its feedback circuit. That is, the output terminal of the operational amplifier opt is connected between the magnetoresistive elements Rb and Rd of the bridge circuit 40, that is, the terminal 12b, and the terminal 12a of the bridge circuit 40 is connected between the magnetoresistive elements Ra and Rc, that is, the terminal 12a is connected to the inverting input terminal of the operational amplifier OP1. It is connected to the power supply Vc via a resistor R3.

On the other hand, the magnetoresistive element R constituting the temperature compensation resistance element 13
1a. A series circuit of R1b and resistor R2 is connected to power supply Vc, and a connection point between magnetoresistive element Rib and resistor R2 is connected to a non-inverting input terminal of operational amplifier OPI. Therefore, the constant voltage applied to the magnetoresistive element R1a. It is divided by R1b and resistor R2 and inputted to operational amplifier OP1 as reference voltage Vs. Thus, the voltage across the resistor R3 is determined by the reference voltage Vs, and the output voltage of the operational amplifier OPI changes in accordance with changes in the resistance value of the entire bridge circuit 40, and a constant current is supplied. That is, even if the resistance values of the magnetoresistive elements Ra to Rd forming the bridge circuit 40 change, a constant current is supplied to the bridge circuit 40.

The output terminal of the bridge circuit 40 is connected to the differential amplifier circuit 4.
Connected to 2. The bridge circuit 40 between the magnetoresistive elements Ra and Rd, that is, the terminal 12d, is connected to the non-inverting input terminal of the operational amplifier OP2, and the magnetoresistive element Rb. The terminal 12c is connected to the non-inverting input terminal of the operational amplifier OP3.

The output terminal of the operational amplifier OP2 is connected to the inverting input terminal via the feedback resistor R4, and is also connected to the inverting input terminal of the operational amplifier OP4 via the resistor Rf. The output terminal of operational amplifier OP3 is connected to the inverting input terminal via feedback resistor R6, and is also connected to the non-inverting input terminal of operational amplifier OP4 via resistor R8. Further, the inverting input terminals of operational amplifiers OP2 and OP3 are connected via a variable resistor R5.

The output terminal of the operational amplifier OP4 is connected to the inverting input terminal via a resistor R9, and is also connected to the output terminal VTA. Non-inverting input terminal of operational amplifier OP4 and resistor R8
The connection point of is connected to the output terminal of the operational amplifier OP5 via a resistor RIO. A constant voltage of the power supply Vc is divided by a resistor Rll and a variable resistor R12 and input as a reference voltage Vt to a non-inverting input terminal of the operational amplifier OP5. The operational amplifier OP50 inverting input terminal is connected to the output terminal.

As described above, the resistance value of the detection element 12 of the magnetic sensor 10 changes in accordance with the rotation of the shaft 2 shown in FIG.

This detection element 12 constitutes a bridge circuit 40 as shown in Figure 'f%3, and a current control circuit 41 is connected to this.
A constant current is supplied through the Therefore, the detection element 1
Bridge circuit 4 according to the change in resistance value of each block of 2.
The connection point of magnetoresistive elements Ra and Rd of 0 and magnetoresistive element R
An unbalanced potential difference occurs between the connection point of h and Re. This is applied to the differential amplifier circuit 42, and a voltage output as a rotation angle signal is obtained from the output terminal VTA. That is, a voltage output that increases linearly with the rotation angle except for the vicinity of the maximum and minimum values can be obtained.

When the ambient temperature of the detection element 12 changes and the resistance values of the magnetoresistive elements Ra to Rd change, the resistance values of the magnetoresistive elements Rla and Rib that constitute the temperature compensation resistance element 13 also change in the same way. Therefore, for example, when the ambient temperature rises and the resistance values of the magnetoresistive elements Ra to Rd increase and the output tends to decrease, the magnetoresistive elements R1a. The current supplied to the bridge circuit 40 by the current control circuit 41 is controlled to increase in accordance with the increase in the resistance value of R1b.

Specifically, when the ambient temperature of the magnetic sensor 10 rises and the resistance values of the magnetoresistive elements Rla and R1b having positive temperature coefficients increase, the input voltage at the non-inverting input terminal of the operational amplifier OPI decreases. Therefore, the output voltage of the operational amplifier OPI decreases and the current supplied to the bridge circuit 40 increases. At this time, each of the magnetoresistive elements Ra to Rd forming the bridge circuit 40, which are in approximately the same environment as the magnetoresistive elements Rla and Rib, has an increased resistance value as well as the magnetoresistive elements Rla and Rib, but as described above, Since the current supplied from the operational amplifier OPI increases, the output corresponding to the rotation angle is ensured without causing a decrease in output due to a rise in ambient temperature.

FIG. 4 shows the output characteristics of the bridge circuit 40, and when the temperature compensating resistance element 13 is not provided, the output decreases as the ambient temperature rises, as shown by the broken line. still,
The upper part of Fig. 4 shows the characteristics when the angle θ in Fig. 1 is 90°, that is, the rotation angle of the shaft 2 is 90°, and the lower part of Fig. 4 shows the characteristics when the angle θ is 0°. The characteristics when .

On the other hand, if the magnetoresistive elements Rla and Rib are interposed with temperature-compensated resistance elements with the same resistance value, the output characteristics will improve due to temperature compensation, but the resistance values of the magnetoresistive elements Ra to Rd will differ. If the angle θ is 90”, the temperature compensation of the output becomes insufficient as shown by the dashed line in FIG. 4. When the angle θ is 0°, the characteristic is shown by the solid line.

In this embodiment, as described above, the resistance values of the magnetoresistive elements Rla and Rib are set to be different, and the angle θ is 9.
It is set so that even when the temperature reaches 0°, the amount of increase in resistance value due to temperature rise is sufficient for temperature compensation, and 344
The output characteristics shown by the solid line in the figure are obtained. Thus, the output of the bridge circuit 40 is maintained at a constant value for the angle θ of the entire measurement region without being affected by changes in ambient temperature, and becomes an output corresponding only to the rotation angle of the shaft 2.

Although the rotation angle sensor configured as described above can be installed in various devices, for example, it is built into a throttle position sensor of an internal combustion engine. FIGS. 5 and 6 show a throttle position sensor 1 incorporating the rotation angle sensor shown in FIGS. They are supported so as to rotate in conjunction with each other.

That is, the throttle position sensor 1 is located between two adjacent recesses 3a. 3b, the housing 3 is made of synthetic resin and has recesses 3a. A shaft 2 is rotatably supported via a bearing 4 on the partition wall 3C between the partition walls 3b.

A lever 5 housed in one recess 3a of the housing 3 is fixed to one end of the shaft 2, and the lever 5 is connected to a throttle shaft (not shown). A return spring 6 is interposed between the housing 3 and the lever 5, and the lever 5 is urged toward a predetermined initial position.

Therefore, as the throttle valve (not shown) is operated, the lever 5 interlocked with the throttle shaft is driven against the biasing force of the return spring 6, and the shaft 2 is rotated.

A magnet member 20 is fixed to the other end of the shaft 2 and housed in the other recess 3b of the housing 3. and,
The magnetic sensor 10 is disposed so as to face the permanent magnet 21 constituting the magnet member 20 and to be located between the magnetic arms 22 and 23 at both ends thereof. As described above, the magnetic sensor 10 includes the element substrate 11, the detection element 12 and the temperature compensation resistance element 13 attached to the surface of the element substrate 11, and is mounted on one surface of the circuit board 30. On the other surface of the circuit board 30, elements such as the operational amplifier OP1 constituting the aforementioned detection circuit are mounted. A plurality of terminals 32 are provided at one end of the circuit board 30 to connect the leads on the front and back surfaces, and a plurality of lead members 7 are connected to the other end. These lead members 7 are embedded within the housing 3, and extend laterally to form a connector 8 integrally with the housing 3. The circuit board 30 is housed and fixed in a groove 3b of the housing 3, and this groove 3b is covered with a cover 9 made of synthetic resin.
It is sealed by.

According to the throttle position sensor 1 equipped with the rotation angle sensor shown in FIGS. 1 to 3, the lever 5 shown in FIG. It rotates 4 times, and the rotation angle signal of the throttle valve can be obtained without contact.

Moreover, the rotation angle sensor used in this example can suppress errors caused by ambient temperature as described above.
Stable detection accuracy can be ensured even in harsh external environments.

C Effects of the Invention Since the present invention is configured as described above, the effects described below can be realized.

That is, in the rotation angle sensor of the present invention, a pattern-shaped ferromagnetic magnetoresistive element in which a horizontal block and a vertical block made of the same material as the ferromagnetic magnetoresistive element constituting the detection element and having different resistance values are connected is mounted on a substrate. Since we decided to provide a temperature-compensated resistance element attached to the sensor element, placed adjacent to the detection element, and connected to the current control circuit, the shaft It is possible to reliably suppress output fluctuations due to changes in ambient temperature in the entire measurement angle range, regardless of the rotation angle of the sensor, and ensure stable detection accuracy. Furthermore, since the temperature compensation resistance element can be formed at the same time as the detection element, it is possible to provide a rotation angle sensor that is easy to manufacture and inexpensive.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a rotation angle sensor according to an embodiment of the present invention.
Figure 2 is a perspective view of the rotation angle sensor, Figure 3 is an electric circuit diagram of the detection circuit, Figure 4 is a graph showing the output characteristics of the bridge circuit with respect to ambient temperature changes, and Figure 5 is the same. FIG. 6 is a longitudinal sectional view of a throttle position sensor incorporating a rotation angle sensor according to an embodiment of the invention, and is a plan view of the throttle position sensor with the cover removed. ...Magnetic sensor. 12...Detection element 20...Magnet member. 30...Circuit board. 41...Current control circuit,...Shaft, 10 1...Element board 3...Temperature compensation resistance element, 1...Permanent magnet. 0... Bridge circuit, 2... Differential amplifier circuit

Claims (1)

[Claims] (1) A ferromagnetic magnetoresistive element with a pattern shape in which a pair of horizontal blocks centered around an element whose longitudinal direction is horizontal and a pair of vertical blocks centered around an element whose longitudinal direction is vertical are connected alternately to a substrate. A shaft for the detection element, comprising a detection element attached to a surface and configured as a bridge circuit by the pair of horizontal blocks and the pair of vertical blocks, and a current control circuit connected to the detection element and supplying a constant current. In a rotation angle sensor that detects the rotation angle of the shaft by changes in magnetic flux accompanying the rotation of the shaft, the sensor is a ferromagnetic magnetoresistive element made of the same material as the ferromagnetic magnetoresistive element constituting the detection element, and whose longitudinal direction is horizontal. Detecting the ferromagnetic magnetoresistive element having a pattern shape in which a horizontal block centered on an element whose resistance value is different from the resistance value of the horizontal block and a vertical block centered on an element whose longitudinal direction is perpendicular to the resistance value of the horizontal block is connected. A temperature-compensating resistor element is provided adjacent to the element, attached to the plate surface of the substrate, and connected to the current control circuit, and the temperature-compensating resistor element is adapted to resist changes in resistance due to changes in ambient temperature of the temperature-compensating resistor element. A rotation angle sensor characterized in that the current supplied to the current control circuit is adjusted accordingly.