JPH01270613A - Apparatus for magnetically detecting position or speed - Google Patents

Abstract

PURPOSE:To detect a position and a speed with high accuracy and high resolving power, by providing a magnetoresistance effect element changing in its internal resistance in proportion to the temp. of an atmosphere other than a plurality of magnetoresistance effect elements. CONSTITUTION:A magnetic drum 2 having a magnetic medium 21 on the surface thereof is fixed to a rotary shaft 1. Magnetic signals N-S, S-N are continuously recorded on the magnetic medium 21 of the drum 2 by magnetization writing. A magnetic sensor 3 has a substrate 31 corresponding to said drum 2, and magnetoresistance effect elements MR1-MR4 and the temp. compensating magnetoresistance effect element MR5 arranged on the side thereof are provided to the substrate 31. Therefore, when the drum 2 is rotated, the magnetic field applied to the elements MR1-MR4 changes corresponding to the magnetic signal N-S and, therefore, the rotary position of the drum 2 can be detected as the resistance change of the elements MR1-MR4. Since this apparatus is constituted so as to correct the inputs or outputs of the elements MR1-MR4 by the output of the element MR5, the outputs of the elements MR1-MR4 are not affected by a temp. change and a position or speed can be detected with high accuracy and high resolving power.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a device for detecting position and velocity, and in particular to temperature compensation of a detection device using a magnetoresistive element, or a device suitable for use therein. This relates to magnetic sensors.

[Conventional technology]

Conventional position detection devices using magnetoresistive elements generally do not take temperature changes in output amplitude into consideration. This is because the output of the magnetoresistive element is waveform-shaped and used as a square wave, so even without temperature compensation there is little effect on the square wave output. However, in order to improve the resolution of position detection, a device with a sine wave output is required. If the output is a sine wave, the resolution can be higher than that of a conventional square wave by using analog values. Regarding this technology, we published JP-A-62-204, 1
This has already been proposed in Publication No. 1-8.

[Problem to be solved by the invention]

However, if the amplitude of the sine wave output changes due to the influence of temperature, an error occurs and temperature compensation is required. Also,
Even when shaping the waveform into a square wave, if temperature compensation is included, higher accuracy and resolution can be achieved.

However, in the prior art described in Section 2, consideration has been given to temperature-compensating the output amplitude of the magnetoresistive element, but since the amplitude of the output voltage changes depending on the temperature, it is difficult to obtain high resolution.

The first object of the present invention is to provide a device for detecting position and velocity with high accuracy and high resolution by compensating for changes in the output of a magnetoresistive element due to temperature and eliminating the influence of temperature. The second purpose is to provide a magnetic sensor suitable for this device.

[Means to solve the problem]

The first object is to provide a first member and a second member that are relatively movable in close proximity, a magnetic recording medium supported by the first member, and a magnetic signal recorded on the magnetic recording medium. , a base of a magnetic sensor supported on the second member, a plurality of magnetoresistive elements supported on the base and whose electrical resistance changes in response to a magnetic signal of the magnetic recording medium, and these magnetoresistive elements. In the device for detecting the relative position and velocity between the first and second members using an electric signal from an effect element, the base body is proportional to the temperature of the atmosphere in which a magnetic sensor is arranged in addition to the plurality of magnetoresistive elements. This is achieved by carrying a second element whose internal resistance changes, and by configuring the output of the latter second element to correct the input or output of the former magnetoresistive element. 2
The purpose of this is to create both a magnetoresistive element on the same insulating substrate that is sensitive to a predetermined external magnetic field and whose internal resistance changes, and an element that is substantially insensitive to this external magnetic field but whose internal resistance changes depending on the ambient temperature. This is achieved by a magnetic sensor structure carrying

[Effect]

The output of the magnetoresistive element in the magnetic sensor that makes up the position detection device changes depending on the temperature, so this temperature is measured and the input voltage of the magnetic sensor is controlled so that the output remains constant with respect to temperature. Alternatively, by making the gain of the circuit that amplifies the output of the magnetoresistive element variable in accordance with the temperature, the output of the position detection device can be kept constant with respect to temperature.

In other words, the second element whose internal resistance changes depending on the temperature of the atmosphere in which the magnetic sensor of the present invention is arranged changes to the magnetoresistive element when the output of the magnetoresistive element tends to decrease due to a change in humidity. Increase the applied input voltage7,
Further, when the output of the magnetoresistive element tends to increase, it acts to reduce the input voltage applied to the magnetoresistive element.

〔Example〕

Hereinafter, the structure of one embodiment of the present invention will be explained with reference to FIGS. 1 to 6. FIG. 1 shows the configuration of a rotational position detection device using a magnetoresistive element. 1 is a rotating shaft such as a motor shaft. A magnetic disk A2 having a magnetic medium 21 on its surface is fixed to the rotating shaft 1. As shown in FIG. A magnetic signal N-8 is continuously recorded on the magnetic medium 21 by magnetized writing. Reference numeral 3 designates a magnetic sensor 3 disposed close to and facing the magnetic ram. This magnetic sensor 3 has a base body 3), and each base body 31 has a plurality of magnetoresistive elements.

Once, when the magnetic tram A2 rotates, the magnetic field applied to the magnetoresistive element changes in accordance with the magnetic signal N-8, so the magnetic tram 2 changes as the resistance change of the magnetoresistive element.
The rotational position of can be detected.

FIG. 2 shows an expanded view of the relationship between the magnetic I spatulas 1 and 2 and the magnetic sensor 3. As shown in the figure, the magnetic medium 21 of the magnetic 1<ram 2 receives a magnetic signal 1f-8 with a recording pitch λ.
, S-N are recorded continuously, and correspondingly, the magnetic sensor 3 has magnetoresistive elements M R+ to M14 and M
It consists of R5. Magnetoresistive element M R+ ~ M R
4 are arranged at intervals of λ/2, and MR3 is arranged in a direction orthogonal to these. Figure 33 shows magnetoresistive element M
Each magnetoresistive element M in the connection diagram of R1 to M, Ra
RI-M and Ra constitute a bridge. In addition, each magnetoresistive element M Ri to MRs is made of permalloy or Ni.
It is made of a thin film such as C0, and its internal electrical resistance changes as shown in FIG. 4 by a magnetic field H in a direction perpendicular to the longitudinal direction. However, there is almost no change in electrical resistance in response to a longitudinal magnetic field. Therefore, when the magnetic driver l\2 shown in FIG. 1 rotates, a magnetic signal magnetic field 1-T as shown in FIG. 4 is applied to each magnetoresistive element M R1 to M R4 of the magnetic sensor 3 by a magnetic signal. . This magnetic field I(.

Since the magnetic ram 2 is continuously generated while the magnetic ram 2 is rotating, the resistance change of the magnetoresistive element MR1, etc. has a continuous waveform as shown in the figure. Furthermore, since the magnetoresistive element MR2 is shifted in position by λ/2 from MRt, the resistance changes as shown by the broken line in the figure. Similarly, magnetoresistive element MR
3 and MR4 also have waveforms as shown. Therefore, the third
Since the DC voltage ■ is applied to the input terminal of the bridge circuit shown in the figure, an output like eQ in FIG. 4 is obtained at the output terminal eo.

The resistance value of each magnetoresistive element changes with temperature, and as the temperature rises, the resistance value also increases.
＝ Having sex. Therefore, as the temperature rises, the output eQ in Figure 3
The amplitude of the output eo decreases, and the temperature characteristic of the output eo with respect to temperature changes with the temperature as shown by the broken line eoi in FIG.

FIG. 5 shows a circuit for compensating for this temperature change. The magnetoresistive element M R5 and fixed resistors R1 to R8 constitute a resistive bridge as shown in the figure, and the output terminals a and b are connected to the input terminal of the amplifier ○P1 via resistors R4 and R5, respectively. Further, a feedback resistor Re is connected between the negative input power and the output of the amplifier. The output of the amplifier OP1 is connected to the power supply terminal of the bridge circuit of the magnetoresistive elements MRL-MR4, and the other end of the power supply terminal is applied with a negative voltage -■. Magnetoresistive element M R1 to MR
The output terminals c and d of the bridge No. 4 are connected to the inputs of the amplifier OP2 via resistors R7 and Rδ. A feedback resistor R9 is connected between the negative input and output of the amplifier OP2. In this circuit configuration, when the temperature is constant, the resistance of the magnetoresistive element M R5 is constant, and the amplifier ○P
1, that is, the input voltage V of the bridge of the magnetic low resistance effect elements MR1 to MR4 is constant. However, as the temperature rises, the resistance value of the magnetoresistive element M R5 increases by 1, so the voltage at the negative input of the amplifier OP1 decreases, and as a result, the input voltage of the bridge of the magnetoresistive elements M R1 to M R4 decreases. ln increases. This input voltage V + n with respect to temperature becomes V In in FIG. Therefore, the amplitude of the output eo of the bridge of the magnetoresistive elements MR1 to MR4 shown in FIG. 5 is exactly canceled out against the temperature, and changes due to temperature are compensated for. As a result, the amplitude of the output Eo of the amplifier ○P2, which is the output of the position detection device, can be compensated for without changing the amplitude with respect to temperature, as shown by the solid line in FIG. Note that since the magnetoresistive element M R5 is arranged in the longitudinal direction with respect to the magnetic signal of the magnetic drum 2, the magnetic signal magnetic field H1
There is no change in resistance due to In addition, magnetoresistive elements MR~MR4 and magnetoresistive elements M for temperature compensation are also provided.
Since R5 is made of the same material and is constructed on the same chip, it undergoes almost the same change in temperature, so temperature compensation can be almost completely achieved.

Furthermore, magnetoresistive elements M R6 and M R1 to M R
If a different material is used, the temperature coefficients of the two will be different, but it is possible to completely compensate for the temperature by adjusting the amplification factor determined by the resistors R5 and R6 of the amplifier ○P1.

Further, in this example, the temperature compensation resistor MR5 is made of a magnetoresistive element, but the same effect can be obtained with other materials as long as the resistance changes with temperature. Furthermore, in the example of FIG. 2, the magnetoresistive element M R5 is arranged so as to receive the magnetic field from the magnetic drum 2 in the longitudinal direction, but if it is arranged at a position where the magnetic field from the magnetic drum 2 does not reach, The direction of the arrangement can be arbitrary.

Figure 7 shows another embodiment of the magnetoresistive element M for temperature compensation.
This is an example in which R5 is placed next to other magnetoresistive elements M Rs to MR4. In FIG. 7, L1 to L5 are lead wire portions of the respective magnetoresistive elements MR1 to MRr, and MR
It has a width sufficiently wider than MR1 to MR5 so that no change in resistance occurs with respect to the signal magnetic field H from the magnetic drum 2. Furthermore, since the magnetoresistive element MR5 is arranged in the longitudinal direction with respect to the signal magnetic field of the magnetic drum 2, no resistance change occurs due to the signal magnetic field. That is,
Since the magnetoresistive element MR5 causes a resistance change only in response to a temperature change, it can be used in combination with FIG. 5 to perform temperature compensation.

FIG. 8 shows a temperature compensation circuit showing another embodiment.

A resistance bridge made up of resistors R1 to R8 and magnetoresistive elements MR5 and a bridge made up of magnetoresistive elements M R1 to M R4 are connected to the DC voltage (1). The output of each bridge is resistor R7, R8 and R4, R3
It is applied to the input terminals of amplifiers ○P1 and OF2 via . Further, feedback resistors Ro and R6 are connected between the negative input terminal and output terminal of each amplifier OP 1 and OF2, and the output of each amplifier OP 1 and OF2 is added to the input of a multiplier MP, and the output Eo of the multiplier MP is is the output of the position detection device. Output V of amplifier OP1. is O in Figure 5
It has exactly the same configuration as the output V + n of P1, and changes in proportion to the temperature as indicated by the one-dot broken line Vc in FIG. Furthermore, as explained in FIG. 5, the output amplitude of the bridge outputs of the magnetoresistive elements M R1 to M Ra decreases depending on the temperature, so the output e of the amplifier OP2 that amplifies this decreases.
02 changes in inverse proportion to the temperature as shown by the broken line in FIG. Once the voltage in Figure 9 ■. The product of and eo is Eo, whose output amplitude does not change with temperature.

FIG. 10 shows another embodiment of the temperature compensation circuit.

For the DC voltage V, the resistors R1 to R3 and the magnetoresistive elements M R5 and M Rt to MRB have the same configuration as in FIG. 9, and the configuration of the amplifier OP1 is also the same as in FIG. The bridge outputs of the magnetoresistive elements MR to MR4 are connected to the input of the variable gain amplifier ■○P via resistors R4 and R5. Variable gain amplifier □ device■OP is amplifier○
This is an amplifier whose internal gain is determined by the output voltage of P1. Therefore, the magnetoresistive elements M R1 to MR
The output amplitude of No. 4 changes with temperature as shown by the broken line in FIG. However, the gain of the amplifier ■○P that amplifies the output changes as indicated by the dotted line in Figure 9, so its output is E.

becomes a constant value with respect to temperature as shown by the solid line in FIG.

Although the present invention has been explained below using an example of a position detection device for a rotating body, the same operation and effect can be obtained even if the present invention is applied to a body that moves in a straight line.

FIG. 11 shows another embodiment of temperature compensation. This embodiment is an example in which temperature detection is shared by magnetoresistive elements M R1 to M R4 for position detection, without using any special temperature detection element. A resistor R1°R2 is connected in series to the power supply V, and the midpoint thereof is connected to the positive input of the amplifier OPI. In addition, the magnetoresistive effect element M R1 ~ connected to the output of the amplifier ○Pl
A resistor R3 is connected in series to the bridge of M R4, and its midpoint 8o is connected to the negative input of the amplifier ○P1 via the resistor R4.

Furthermore, the amplifier OP is connected from the output terminal of the bridge of the magnetoresistive elements MR1 to MR4 through the respective resistors Ro and Rho.
Connect to input 2. In addition, resistors R13 and R7 are connected in series to the output of the amplifier OF +, and from the midpoint to the resistor Rδ
to the input of the amplifier OP2. Each amplifier○P1. Feedback resistors R5 and R11 are connected between the output and negative input of P2. Since a bias is applied to the amplifier pt by the potential at the midpoint bo between the resistors R1 and R2, a certain voltage V + n is generated at the output of 0I)1. In addition, each magnetoresistive element 7-M R1 and M R
2 and M
The resistance change seen from the series terminal of 3 is canceled out and disappears.
Since it is a constant value, the potential at point ao is constant in the position detection operation. However, if the temperature increases by 1, the magnetoresistive effect element M
The resistance of R1 to M Ra increases. Since the resistance of the fixed resistor R3 hardly changes with temperature, the potential at point aO decreases as the temperature rises. Therefore the amplifier OP
Since the negative input potential of l decreases, the output of OPl increases, so the potential of point aQ is kept constant.

This changes depending on the temperature of the magnetoresistive elements M, R1 to MR.
4 increases, thereby compensating for the decrease in the amplitude of the position detection output. As shown in Fig. 6, the magnetoresistive effect element M Rl-
The voltage V In applied to M R4 is controlled to keep the amplitude of the position detection output Eo constant against temperature changes. Further, resistors R6 and R7 provide a bias so that the offset of the circuit does not change due to temperature. In other words, if an offset occurs in the frizz output of the magnetoresistive elements M Rs to M Ra, the voltage vI
Since n changes, this offset voltage also changes. Therefore, by canceling this offset using resistors R6 and R7, the offset change in the output of the amplifier OP2 can be removed.

As described above, in this embodiment, temperature compensation is made possible without using any temperature detection element other than the magnetoresistive element for position detection.

In the example of FIG. 11, the bridge is constructed using four magnetoresistive elements, but it can be used in exactly the same way for a position detection device using two or one magnetoresistive elements. Further, it is best to use a resistor R3 in FIG. 11 with a small temperature coefficient, but the same effect can be obtained as long as the resistor R3 is different from the temperature coefficient of the magnetoresistive element. Furthermore, if this resistance R3 has a small value compared to the magnetoresistive element, it is advantageous to increase the voltage applied to the magnetoresistive element. Therefore, good temperature compensation can be achieved by adjusting the amplification factor of the amplifier OP i using the resistors Ra and R5 depending on the value of the resistor R3.

FIG. 12 shows the arrangement of magnetoresistive elements M and R5.
Let's talk about other configurations.

In FIG. 12, an element MRB for detecting ambient temperature is supported on an insulating base 31, and is covered with an insulating coating G such as a glass. Then, the insulating film G supports the magnetoresistive elements MRi to MR4. At this time, element MR5 is positioned directly below magnetoresistive element MR3.

As described above, with this configuration, the magnetic field H1 of the magnetic signal N-8 from the magnetic medium acts on M R3 to change the magnetic resistance of M R3. Has a magnetic shielding effect against MR5. This is clear from the fact that a magnetic closed circuit is formed in which the magnetic field from the magnetic signal N-8 passes through MR3. Therefore, the resistance of MR5 changes only under the influence of temperature.

At this time, when current flows through MRs, it generates heat, but M
Since MR5 is placed very close to the back surface of Rs, MR5 can accurately detect the temperature state of MRs, and is sensitive to the temperature of the space in which the magnetic sensor is placed as shown in other examples. Compensation sensitivity can be improved compared to the conventional one.

〔Effect of the invention〕

As described above, the first invention provides a first member and a second member that are relatively movable in close proximity, a magnetic recording medium supported by the first member, and a magnetic recording medium supported by the first member. a recorded magnetic signal, a base of a magnetic sensor supported on the second member, and a plurality of magnetoresistive elements supported on this base whose electrical resistance changes in response to the magnetic signal of the magnetic recording medium; , in a device that detects the relative position and velocity between the first and second members by electric signals from these magnetoresistive elements, the base body is an atmosphere in which a magnetic sensor is arranged in addition to the plurality of magnetoresistive elements. carries a second element whose internal resistance changes in proportion to the temperature of the second element;
Since the input or output of the former magnetoresistive element is corrected using the output of the former element, the output of the magnetoresistive element is not affected by temperature changes, making it possible to obtain a high-precision, high-resolution device. can.

Further, the second invention includes a magnetoresistive element whose internal resistance changes in response to a predetermined external magnetic field on the same insulating substrate, and a magnetoresistive element whose internal resistance changes depending on the ambient temperature although it is not substantially sensitive to the external magnetic field. Since both of the elements were supported, the first
A magnetic sensor suitable for application to the invention can be provided.

Note that the present invention is applicable to either a device that processes the output of a magnetic sensor to detect position or velocity, or a device that directly detects the output of a magnetic sensor as an analog value, but it is particularly applicable to the latter. It has a remarkable effect.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a position detection device according to the present invention, FIG. 2 is an exploded view of a magnetic sensor and a magnetic drum according to an embodiment of the present invention, and FIG.
The figure is a connection diagram of the magnetic sensor of the present invention, Figure 4 is a diagram explaining the characteristics and operation of the magnetoresistive element, Figure 5 is an embodiment of the temperature compensation circuit of the present invention, and Figure 6 is the characteristic of Figure 5. An explanatory diagram, FIG. 7 is a developed diagram showing another embodiment of the magnetic sensor of the present invention, and FIG.
The figure is a temperature compensation circuit diagram of another embodiment of the present invention, FIG. 9 is a characteristic diagram of FIG. 8, FIG. 10 is a temperature compensation circuit diagram of another embodiment of the present invention, and FIG. 11 is a diagram of the present invention. FIG. 12 is a sectional view showing the structure of another embodiment. 1. Rotating shaft, 2. Magnetic drum, 3. Magnetic sensor, 2
1. Magnetic medium, 31. Base, MRt to MR4 magnetoresistive element, MRs... Element whose resistance changes depending on temperature.

Claims (1)

[Claims] 1. A first member and a second member that are relatively movable in close proximity, and a magnetic recording medium supported by the first member;
A magnetic signal recorded on the magnetic recording medium, a base of a magnetic sensor supported on the second member, and a plurality of sensors supported on the base whose electrical resistance changes in response to the magnetic signals of the magnetic recording medium. In a device that detects relative positions and velocities between first and second members using magnetoresistive elements and electric signals from these magnetoresistive elements, the base body includes a magnetic sensor in addition to the plurality of magnetoresistive elements. It carries a second element whose internal resistance changes in proportion to the temperature of the atmosphere in which it is placed, and is configured to correct the input or output of the former magnetoresistive element with the output of the latter second element. A device that magnetically detects position and speed. 2. An apparatus for magnetically detecting position and velocity according to claim 1, wherein the second element is made of the same material as the magnetoresistive element. 3. The device according to claim 2, characterized in that the magnetoresistive element and the latter second element are arranged on the same chip. Device to detect. 4. An apparatus for magnetically detecting position and velocity according to claim 2, wherein the longitudinal direction of the second element is aligned with the direction of the magnetic field of the magnetic signal. 5. The device according to claim 2, wherein the second element is arranged at a position that is not substantially sensitive to the magnetic signal recorded on the magnetic recording medium. A device that detects 6. A first member and a second member that are relatively movable in close proximity, and a magnetic recording medium supported by the first member;
A magnetic signal recorded on the magnetic recording medium, a base of a magnetic sensor supported on the second member, and a plurality of sensors supported on the base whose electrical resistance changes in response to the magnetic signals of the magnetic recording medium. A device for detecting relative positions and speeds between first and second members using magnetoresistive elements and electric signals from these magnetoresistive elements, further comprising a temperature detection element for detecting an ambient temperature of the magnetic sensor. . A device for magnetically detecting position and velocity, characterized in that the input voltage of the magnetic sensor is controlled according to the output of the temperature detection element. 7. An apparatus for magnetically detecting position and velocity according to claim 6, characterized in that the temperature detection element and the magnetoresistive element are carried on the same chip. 8. A first member and a second member that are relatively movable in close proximity, and a magnetic recording medium supported by the first member;
A magnetic signal recorded on the magnetic recording medium, a base of a magnetic sensor supported on the second member, and a plurality of sensors supported on the base whose electrical resistance changes in response to the magnetic signals of the magnetic recording medium. A device for detecting relative positions and speeds between first and second members using magnetoresistive elements and electrical signals from these magnetoresistive elements, comprising: an element for detecting the ambient temperature in which the magnetic sensor is arranged; 1. An apparatus for magnetically detecting position and velocity, characterized in that the device is configured to output the product of the output of this element and the output of the magnetoresistive element. 9. The device according to claim 8, wherein the element is made of the same material as the magnetoresistive element and is supported on the same chip as the magnetoresistive element. A device that detects speed. 10, a first member and a second member that move relatively in close proximity;
a magnetic recording medium supported on the first member, a magnetic signal recorded on the magnetic recording medium, a base of a magnetic sensor supported on the second member, and a magnetic sensor supported on the base; A plurality of magnetoresistive elements whose electrical resistance changes in response to magnetic signals from the magnetic recording medium, and detecting relative positions and speeds between the first and second members using electrical signals from these magnetoresistive elements. In the device, an element is provided for detecting the ambient temperature of a space in which the magnetic sensor is arranged, and an amplification gain for amplifying the output of the magnetoresistive element is adjusted based on the output of the element. A device that magnetically detects position and speed. 11. The device according to claim 10, wherein the element is made of the same material as the magnetoresistive element and is supported on the same base as the magnetoresistive element. A device that detects speed. 12, a first member and a second member that move relatively in close proximity;
a magnetic recording medium supported on the first member, a magnetic signal recorded on the magnetic recording medium, a base of a magnetic sensor supported on the second member, and a magnetic sensor supported on the base; A plurality of magnetoresistive elements whose electrical resistance changes in response to magnetic signals from the magnetic recording medium, and detecting relative positions and speeds between the first and second members using electrical signals from these magnetoresistive elements. In the device, an element having a temperature coefficient different from the magnetoresistive element is connected in series with the magnetoresistive element, and a voltage applied to the magnetoresistive element is applied using a potential at a midpoint between these elements. A device that magnetically detects position and speed. 13. Both a magnetoresistive element that is sensitive to a predetermined external magnetic field and whose internal resistance changes, and an element that is not substantially sensitive to this external magnetic field but whose internal resistance changes depending on the ambient temperature are placed on the same insulating substrate. Carrying magnetic sensor. 14. The device according to claim 13, characterized in that the latter element compensates the amplitude of the output signal obtained from the former magnetoresistive element so that it does not change with temperature. magnetic sensor. 15. The magnetic sensor according to claim 13, wherein the magnetoresistive element and the element whose internal resistance changes depending on temperature are made of the same material and supported on the same substrate. 16. A magnetic sensor according to claim 13, characterized in that a magnetoresistive element is supported via an insulating film on an element whose internal resistance changes depending on temperature. 17. The magnetic sensor according to claim 16, wherein the magnetoresistive element has a magnetic shielding effect with respect to the former element.