JPS6315529B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for moving a magnetic signal recorded in a magnetic storage medium formed in a predetermined shape in the form of repeating magnetization having a predetermined interval by moving relative to the magnetic storage medium. The present invention relates to a position detector that detects the relative position or velocity of the magnetic storage medium and the magnetic sensor by reading the information with a magnetic sensor.

As magnetic sensors used in this type of position detector, ferromagnetic metal thin film magnetoresistive elements (hereinafter referred to as MR elements) and Hall elements are known.

Typically, for magnetic signals, the signal output values obtained from these magnetic sensors become significantly smaller as the temperature increases. For example, in the case of an MR element made of an iron-nickel alloy, the temperature coefficient of its resistance change rate Δρ/ρ is approximately -0.33%/°C. This changes the signal magnetic field to the resistance change rate Δρ/ρ of the MR element.
This means that the signal output value when detected via the sensor is approximately 33% lower at 100°C than at 0°C. Therefore, in general, as the temperature increases, accurate position or velocity detection becomes more difficult.

Therefore, conventional position detectors have problems such as the operating temperature being limited to a narrow range and the need for a temperature correction circuit.

An object of the present invention is to easily reduce fluctuations in the signal output value due to temperature fluctuations by devising the configuration of the position detector, and to provide a position detector with excellent temperature resistance characteristics. It is something to do.

The present invention provides a magnetic storage medium in which a magnetic signal is recorded in the form of repeating magnetization having a predetermined interval;
The support for the magnetic storage medium and the magnetic storage medium arranged to sense the magnetic signal include a magnetic sensor that moves relative to each other, a support for the magnetic sensor, and a base that supports both of the supports. The position detector is characterized in that the distance between the magnetic sensor and the magnetic storage medium decreases as the temperature increases and increases as the temperature decreases.

Next, the present invention will be described in detail with reference to the drawings regarding several embodiments in which an MR element is used as a magnetic sensor. As a first example, a first example of an angle detector that detects the rotation angle of a rotating shaft
This will be explained using Figures 5 to 5. FIG. 1a is a schematic configuration diagram thereof, and FIG. 1b is a front view of FIG. 1a viewed from the x direction so as to clarify the positional relationship between the magnetic storage medium and the magnetic sensor. Reference numeral 4 denotes a magnetic storage medium, and the main components of its support are a rotating shaft 1 and a cylindrical support 2 attached to it via a mounting jig 3.
It consists of The magnetic signal is recorded in the form of repeated magnetizations 5 having equally spaced bit lengths P on the surface of the cylindrical support 2, and the magnetic sensor 7 detects the magnetic storage medium 4 as the rotating shaft 1 rotates. The magnetic sensor is mounted on the base 6 via a magnetic sensor support 8 at a position a predetermined spacing D away from the surface of the magnetic storage medium 4 so that changes in the magnetic field generated from the magnetic storage medium 4 can be sensed. The signal detected by the magnetic sensor 7 is extracted via a reproducing circuit 9.

This first embodiment is characterized in that the coefficient of thermal expansion α ₁ of the cylindrical support 2 is larger than the coefficient of thermal expansion β ₁ of the base 6 .

FIG. 2 shows an example of the magnetic sensor 7, in which strip-shaped MR elements 11 to 18 are mounted on a substrate 10.
are formed in parallel with an interval of 1/4P (P is the bit length).

FIG. 3 shows an example of the connection between the magnetic sensor 7 and the reproducing circuit 9.

The MR elements are MR elements 11, 13, 15 and 17.
The MR elements 12, 14, 16 and 18 are also connected to form a bridge.
The regeneration circuit 9 includes two sets of a differential amplifier 19 and a comparator 20 whose output is input and V _cp is used as a comparison level, and the output of each comparator 20 is taken out as an A-phase output and a B-phase output. It is composed of Signal outputs from each set of MR elements are input to different differential amplifiers 19, respectively.

The process of reproducing magnetic signals in the reproducing circuit 9 will be explained using FIG. FIG. 4a schematically shows the MR element 1 by stretching the magnetic storage medium 4 in a straight line.
1 to 18. The MR elements 11, 13, 1 are
A signal output (V _A ) 21 as shown in FIG. 4b is obtained from the bridge composed of 5 and 17. This signal output 21A is amplified to a desired magnitude by an amplifier 19, and further pulsed by a comparator 20 at a comparison level V _cp , thereby converting it into bits of the magnetic storage medium 4 as shown in FIG. 4c. A corresponding angular position signal (A phase output) 22 is obtained. Similarly, from the bridge composed of MR elements 12, 14, 16, and 18, an angular position signal (B-phase output) 23 whose phase is delayed by 1/4P with respect to the A-phase output 22 is obtained. (Figure 4d). The phase relationship between the A-phase output 22 and the B-phase output 23 becomes exactly opposite when the moving direction of the magnetic storage medium 4 is reversed. In this manner, the rotation angle of the rotating shaft 1 is determined by counting the signal pulses obtained by electrically processing the A-phase output 22, the B-phase output 23, or both of these outputs. In addition, the direction of rotation is determined by both outputs 22,
It is detected by the phase relationship of 23.

FIG. 5 is a diagram for explaining the temperature correction operation according to the present invention, and shows the magnitude of the signal output (V _A ) 21 (or V _B ) obtained from the MR element and the spacing D from the surface of the magnetic storage medium 4. It shows the relationship between

Generally, when a magnetic signal is written to the magnetic storage medium 4 by repeating magnetization 5 of bit length P, the signal magnetic field strength at spacing D is approximately proportional to exp(-π/PD)... do. Therefore, the amplitude of the signal output from the MR element becomes smaller as the spacing D becomes larger.

In FIG. 5, 24 is a curve showing an example of the relationship between the signal output amplitude from the MR element and the spacing D at room temperature, and 25 is a curve showing an example of the relationship between the signal output amplitude from the MR element and the spacing D at room temperature. This is a similar curve when the As is clear from this figure, when the spacing at room temperature is D _p , MR
The magnitude of the reproduction output obtained from the element corresponding to the P point decreases to the magnitude corresponding to the Q point at high temperatures. and,
The degree of this decrease increases as the temperature increases.

According to the configuration of the first embodiment, the cylindrical support 2
Since the thermal expansion coefficient α ₁ of the base 6 is larger than the thermal expansion coefficient β ₁ of the base 6, when the temperature rises, the spacing D
As the temperature decreases and the temperature decreases, this has the effect of increasing the spacing. The amount of change ΔD in the spacing D due to this temperature rise is determined by subtracting the amount of expansion of the cylindrical support 2 and the base 6 in the radial direction. When the radius of the cylindrical support 2 is R and the amount of temperature rise is ΔT, ΔD is expressed by the following formula.

ΔD= _α1・R・ΔT− _β1・(R+D)・ΔT≒( _α1 − _β1 )・R・ΔT……For example, as the columnar support 2, Al( _α1 ≒23.2×
10 ^-6 /℃), Fe (β ₁ ≒ 11.2×
10 ^-6 /℃), R=20mm, ΔT=100℃, D=
If it is 200μm, ΔD≒24μm... As the spacing D decreases as the temperature rises, the reproduced output from the MR element becomes Q
Recover from point equivalent to S point.

According to the measurements made by the inventors, under the above configuration conditions, the magnetic storage medium 4 has a thickness of 10 μm.
A magnetic signal written with a bit length P of approximately 500 μm is applied to a Co-P medium with a width of 20 μm and a thickness of 20 μm.
When detecting reproduction with a strip-shaped MR element made of a 500 Å Fe-Ni alloy, the decrease in reproduction output due to temperature rise is suppressed to about half of the temperature change equivalent to the resistance change rate Δρ/ρ of the MR element. It was done.

FIG. 6 shows a second embodiment of the angle detector of the present invention, in which FIG. 6a is a schematic configuration diagram thereof, and FIG. This example differs from the first example in that the magnetic signal is applied to the magnetic storage medium 26 formed on the plane of the cylindrical support 2, which is magnetized with bit lengths P equally spaced along its circumference. 27, and the magnetic sensor 7 is disposed at a position a predetermined spacing D above the magnetic storage medium 26 in the Z direction.

Here, the thermal expansion coefficient α ₂ of the rotating shaft 1 is configured to be larger than the thermal expansion coefficient β ₂ of the magnetic sensor support 28 . Therefore, spacing D
becomes smaller as the temperature rises, so this angle detector has the same temperature compensation effect as the first embodiment.

FIG. 7 shows a third embodiment of the angle detector,
Figure a is a schematic configuration diagram thereof, and figure b is a front view seen from the x direction. This is because, compared to the second embodiment, the magnetic storage medium 26 is formed below the cylindrical support 2, and as a result, the magnetic sensor 7 is
The difference is that the magnetic storage medium 26 is disposed at a position downward in the Z direction by a predetermined spacing D.

Here, the thermal expansion coefficient β ₃ of the rotating shaft 1 is configured to be smaller than the thermal expansion coefficient α ₃ of the magnetic sensor support 29. Therefore, similarly to the above embodiment, the spacing D becomes smaller as the temperature rises.

FIG. 8 shows a linear scale for detecting the amount of linear displacement as a fourth embodiment of the present invention, and FIG. It is a diagram. The magnetic storage medium 30 has a linear flat plane, and is placed on the plane of the support 33 attached to the base 31 in the linear direction (y direction).
The magnetic sensor 7 is formed so as to have repeated magnetization 32, and the magnetic sensor 7 is spaced apart from the magnetic storage medium 30 by a predetermined spacing D so as to be able to sense the signal magnetic field. A magnetic sensor support 34 is attached to the base 31 via a linear movement mechanism 35 so as to be movable.

Here, the support body 33 of the magnetic storage medium 30 is configured such that the thermal expansion coefficient α ₄ is larger than the thermal expansion coefficient β ₄ of the base 31. Therefore, the spacing D is
Since it decreases with increasing temperature, this linear scale has a temperature compensation effect similar to some of the angle detectors described above.

FIG. 9 shows a fifth embodiment of the present invention.
is a schematic configuration diagram thereof, and b is a side view seen in the y direction. This differs from the fourth embodiment in that the magnetic storage medium 30 and the magnetic sensor 7 are arranged in the Z direction with respect to the base 37.

In this case, the structure is such that the thermal expansion coefficient α ₅ of the support 38 of the magnetic storage medium 30 is larger than the thermal expansion coefficient β ₅ of the support 39 of the magnetic sensor 7 . Therefore, similarly, the spacing D becomes smaller as the temperature rises.

FIG. 10 shows a sixth embodiment of the present invention, in which FIG. 10a is a schematic configuration thereof and FIG. 10b is a side view seen in the y direction. This differs from the fourth embodiment in that the support 40 of the magnetic sensor 7 is configured in an arm shape.

In this case, the support body 40 of the magnetic sensor 7 is configured such that the thermal expansion coefficient α ₆ is larger than the thermal expansion coefficient β ₆ of the base 41. Therefore, similarly,
The spacing D becomes smaller as the temperature increases.

FIG. 11 shows a seventh embodiment of the present invention; FIG. 11a is a schematic configuration diagram thereof, and FIG. 11b is a side view seen in the y direction. This configuration is very similar to the sixth embodiment shown in the previous figure, but the support 44 of the magnetic sensor 7 is fixed to the base 43, and the support 45 of the magnetic storage medium 30 is fixed to the base 43. Linear motion mechanism section 5
The difference is that it is configured to move in the y direction through 1.

In this case, as in the sixth embodiment, the thermal expansion coefficient α ₇ of the support 44 of the magnetic sensor 7 is the same as that of the base 43.
It is constructed so that the coefficient of thermal expansion β is larger than ₇ , and has a similar temperature compensation effect.

FIG. 12 shows an eighth embodiment of the present invention, and FIG. 12a is a schematic configuration diagram thereof, and FIG. 12b is a side view seen in the y direction. This is a configuration very similar to the fourth embodiment, but the magnetic sensor 7 is connected to the base 46.
A support 47 is fixed, and the magnetic storage medium 3
The support body 48 of 0 moves through the linear motion mechanism 52
The difference is that it is configured to move in the direction.

In this case, as in the fourth embodiment, the thermal expansion coefficient α ₈ of the support 48 of the magnetic storage body 30 is the same as that of the base 46.
The thermal expansion coefficient β is larger than ₈ , and has a similar temperature compensation effect.

FIG. 13 shows a ninth embodiment, and FIG. 13A is a schematic configuration diagram thereof, and FIG. 13B is a side view seen in the y direction. This has a configuration very similar to the fifth embodiment, but the support 5 of the magnetic sensor 7 is attached to the base 53.
4 is fixed, and the support body 54 of the magnetic storage medium 30 is configured to move in the y direction via a linear motion mechanism section 55.

In this case, just like the fifth embodiment, the thermal expansion coefficient α ₉ of the support 54 of the magnetic storage medium 30 is configured to be larger than the thermal expansion coefficient β ₉ of the magnetic sensor support 54, and the same Has temperature compensation effect.

FIG. 14 shows a tenth embodiment of the present invention, and FIG. 14a is a schematic configuration diagram thereof, and FIG. In this embodiment, magnetic storage medium 56
is formed on the side surface of a cylindrical support 58 attached to a base 57 so as to have repeated magnetization 59 along its circumferential direction, and the magnetic sensor 7 is attached to a support 61. The base is rotated through a rotational movement mechanism 60 so that it can rotate around the cylindrical support 58 while maintaining a predetermined spacing D away from the magnetic storage medium 56 so that the signal magnetic field can be sensed. It is attached to a stand 57. This is an angle detector that detects angles by rotating the magnetic sensor 7 around a cylindrical support 58, unlike the first to third embodiments.

Here, a cylindrical support 58 of a magnetic storage medium 56
The base 57 is configured such that its thermal expansion coefficient α ₁₀ is larger than the thermal expansion coefficient β ₁₀ of the base 57, and has a similar temperature compensation effect.

FIG. 15 shows an eleventh embodiment of the present invention; FIG. 15a is a schematic configuration diagram thereof, and FIG.
B′ cross-sectional view. This is the same type of angle detector as the tenth embodiment shown in the previous figure, but a magnetic signal is applied to a magnetic storage medium 62 formed on the plane of a cylindrical support 58, which is magnetized along its circumference. The points recorded in the form of 63 repetitions and the magnetic sensor 7 attached to the support 64 are connected to this magnetic storage medium 62.
However, the difference is that it is disposed at a position a predetermined spacing D apart in the upper direction in the Z direction.

Here, the coefficient of thermal expansion α ₁₁ of the cylindrical support 58 is:
It is configured to have a thermal expansion coefficient β ₁₁ larger than that of the magnetic sensor support 64, and has a similar temperature compensation effect.

FIG. 16 shows a twelfth embodiment of the present invention, and FIG. 16a is a schematic configuration diagram thereof, and FIG. This is the same type of angle detector as the 10th and 11th embodiments shown in the previous figure and the figure before the previous figure, but the magnetic signal is transmitted on the plane facing the base 57 of the coaxial cylindrical support 59. A magnetic storage medium 62 formed in
The points recorded in the form of repeating magnetization 63 along the circumference and the magnetic sensor 7 attached to the support 66 are positioned at a predetermined distance near the base 57 with respect to the magnetic storage medium 62. The difference is that they are arranged at positions separated by pacing D.

Here, the thermal expansion coefficient α ₁₂ of the magnetic sensor support 66 is configured to be larger than the thermal expansion coefficient β ₁₂ of the coaxial columnar support 59, and has a similar temperature compensation effect.

Next, the scope of application of the present invention will be described. The materials for the components of the various position detectors described above may be any combination of materials as long as they satisfy α _i >β _i , i=1 to 12... Further, the magnetic sensor is not limited to an MR element, but may be one whose magnetoelectric conversion efficiency decreases as the temperature rises, such as a Hall element.
Furthermore, the magnetic storage medium 4 is not limited to the above-mentioned example, and may be γ-Fe ₂ O ₃ or a rolled magnet.

In the above, in order to achieve a configuration with a temperature compensation effect in which the spacing between the magnetic storage medium and the magnetic sensor becomes smaller as the temperature rises and becomes larger as the temperature falls, the spacing between the magnetic storage medium and the magnetic sensor in the position sensor is Although the method for selecting the combination of expansion coefficients has been described, the method is not limited to this, and in short, any configuration may be used as long as the spacing is temperature compensated.

As described above, according to the present invention, it is possible to achieve a position detector with excellent temperature resistance characteristics in which fluctuations in signal output values due to temperature fluctuations are small.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram showing an embodiment of the present invention, in which a is a perspective view, b is a front view, Fig. 2 is a perspective view showing an example of a magnetic sensor consisting of an MR element, and Fig. 3 is a perspective view of a magnetic sensor. A circuit diagram showing an example of connection with the reproducing circuit, Figures 4a to d are diagrams showing the magnetic signal reproducing process, and Figure 5 shows the relationship between the signal output obtained from the MR element and spacing using temperature as a parameter. It is a diagram. 6 and 7 are views showing other embodiments of the present invention, in which a is a perspective view, b is a front view, and FIGS. 8 to 13 are views showing still other embodiments, in which a is a perspective view, and b is a front view. Perspective view, b is side view,
14 to 16 are views showing still other embodiments, in which a is a perspective view and b is a sectional view AA', BB' or CC'. 1... Rotating shaft, 2, 58, 59... Cylindrical support, 3... Mounting jig, 4, 26, 30, 56, 6
2...Magnetic storage medium, 5, 27, 32, 59, 6
3... Magnetization, 6, 31, 37, 41, 43, 4
6,53,57...base, 7...magnetic sensor,
8, 28, 29, 34, 39, 40, 44, 4
7, 54, 61, 64, 66...Magnetic sensor support, 9...Reproduction circuit, 10...Substrate, 11-1
8...MR element, 19...Differential amplifier, 20...
Comparator, 21...MR element bridge regeneration output, 22...A phase output, 23...B phase output, 24
...MR magnetic sensor output amplitude at room temperature, 25...
...MR magnetic sensor output amplitude at high temperature, 33,3
8, 42, 45, 48, 54... Support for magnetic recording medium, 35, 49, 50, 51, 52, 55...
...Linear motion mechanism section, 60, 65, 67... Rotary motion mechanism section.

Claims (1)

[Claims] 1. A magnetic storage medium in which magnetic signals are recorded in the form of repeating magnetization with predetermined intervals, a support for this magnetic storage medium, and a support that moves relative to the magnetic storage medium and senses the magnetic signals. A magnetic sensor comprising a plurality of strip-shaped ferromagnetic magnetoresistive elements arranged in parallel at a predetermined distance apart from each other; a support for the magnetic sensor; and a base supporting a support, such that the distance between the magnetic sensor and the magnetic storage medium decreases as the temperature increases and increases as the temperature decreases while maintaining a parallel positional relationship with each other. A position detector characterized in that at least two of the magnetic sensor support, the magnetic storage medium support, and the base have different coefficients of thermal expansion.