JP2550085B2 - Absolute position detector - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a position detecting device, and more particularly to a device for magnetically detecting an absolute position by analog output of a magnetic sensor.

[Conventional technology]

As a conventionally known apparatus for magnetically detecting a position, there is one described in Japanese Patent Application Laid-Open No. 61-22205 previously developed by us.

The one described in this publication detects a magnetic signal magnetized on a magnetized track by a magnetoresistive effect element.

A technique equivalent to this is also described in Japanese Utility Model Laid-Open No. 58-41448.

[Problems to be solved by the invention]

In the above-mentioned conventional technique, the resolution is determined by the magnetizing pitch of the magnetic signal magnetized on the magnetized track, and it is impossible in principle to detect a fine position smaller than this magnetizing pitch.

Further, in the above-mentioned published patent publication, 2 ⁿ
There is a problem that a bit track is required and the device becomes large.

Furthermore, since a magnetoresistive effect element is required for each track, a large number of output signal lines are required, the structure becomes complicated, and the wiring process becomes difficult.

An object of the present invention is to provide a small-sized magnetic absolute position detection device having high resolution.

[Means for solving problems]

The present invention relates to a first and a second member that move relative to each other, and a magnetic recording medium having a large number of small magnetism-producing bodies provided on the first member and recorded so as to be aligned along the relative movement direction. A magnetoresistive effect element provided on the second member so as to be close to the magnetic recording medium so as to be sensitive to the magnetic field of the magnetic body, and is changed by relative movement of the first and first members. In an absolute position detecting device for detecting an absolute position between the two members based on a resistance change of the magnetoresistive element, a pair of S magnetic poles and N magnetic poles formed on the small magnetic body are arranged in a direction in which the small magnetic bodies are arranged. The small magnets are arranged so that the magnetic poles of the adjacent small magnets have the same polarity as each other, and the width length in the direction perpendicular to the arrangement direction of the small magnets depends on the position in the relative movement direction. change Thus, the absolute position detecting device is characterized in that the small magnetic body is formed and the longitudinal direction of the magnetoresistive effect element is arranged so as to be orthogonal to the arrangement direction of the small magnetic body.

[Action]

Since the small magnets are arranged so that the magnetic poles of the adjacent small magnets have the same polarity as each other, there is more magnetic flux that the magnetoresistive effect element is sensitive to, as compared with the case where the magnetic poles of different polarities are adjacent to each other. Therefore, the detection output of the magnetoresistive effect element increases.

Further, the small magnetic body is formed so that the width length in the direction perpendicular to the arrangement direction of the small magnetic body changes depending on the position in the relative movement direction, and the longitudinal direction of the magnetoresistive element is orthogonal to the arrangement direction of the small magnetic body. Since they are arranged, the detection output of the magnetoresistive effect element changes depending on the difference in the width of the small magnet. The positions of the first member and the second member can be detected by the change in the detection output.

〔Example〕

The configuration of an embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a perspective view showing an embodiment of the present invention. In the figure, reference numeral 1 denotes a rotary shaft, and a carrier (first member) 2 such as aluminum is provided on the rotary shaft 1.

On the outer peripheral surface of the carrier 2, a magnetic medium 2A made of a resin mixed with magnetic powder and having a thickness of about 80 (μm) is applied.

On the magnetic medium 2A, as shown by the magnetic signals N and S, magnetic generators are provided with a pitch λ in the rotational direction by a magnetic recording method.

Further, the small small magnetized body having the N magnetic pole and the S magnetic pole is recorded such that the width thereof linearly decreases in this example in the rotating direction.

The magnetized body can be read as a magnet. A magnetic sensor 3 is fixed to face the carrier 2. Magnetic sensor (second
Member 3) is a magnetoresistive effect element (hereinafter abbreviated as MR element) _Ra
And R _b . The carrier 2 and the magnetic sensor 3 are expanded and shown in detail in FIGS. 2 (A) and 2 (B). The carrier 2 has one track A divided into a magnetic signal recording part 21 and a magnetic signal non-recording part 20. If the track width is l ₂ , the maximum width of the magnetic signal is l ₁ and the carrier 2 It is recorded that the width l ₁ changes depending on the position. The magnetic sensor 3 is composed of two MR elements R _a and R _b , and the distance between them is λ / 2. The length l ₀ of the MR elements R _a and R _b is almost the same as the track width l ₂ , but the MR elements R _a and R _b which are at least longer than the width l ₁ are arranged in the longitudinal direction. It has the characteristics shown in FIG. 3 for the magnetic field in the perpendicular direction. The electric resistance changes with respect to the magnetic field, and the resistance changes similarly with respect to both positive and negative magnetic fields. In the ferromagnetic magnetoresistive effect element, the resistance is maximum when the magnetic field is zero, and the resistance decreases when a magnetic field is applied. FIG. 4 shows a connection diagram of the magnetic sensor. MR element R _a , R
_b is connected in series as shown, and is further connected in series with an MR element R arranged so as not to be influenced by a fixed resistance or a magnetic field, and a DC power supply V is applied to both ends of the MR element R to take out an output e from the midpoint. It has a circuit configuration.

Now, assuming that the carrier 2 rotates in the direction of the arrow, each MR element
R _a and R _b receive the magnetic field of the magnetic signal and the resistance changes as shown in FIG. At the beginning, the width l _{1 of the} magnetic signal is small and a part of the length l ₀ of the MR elements R _a and R _b does not receive the magnetic field and the resistance changes little with respect to the value R _{0 of the} magnetic field 0, but the magnetic drum rotates. However, since the width l _{1 of the} magnetic signal increases as the angle θ increases, most of the MR elements R _a and R _b and the length l ₀ are affected by the magnetic field, and the resistance change also increases. Since the phases of the resistance changes of MR elements R _a and R _b are 180 ° out of phase, adding a resistance that changes in a sinusoidal manner cancels the pulsating component, and as shown in the figure, R _a + R _b
Will be a straight line. Therefore, the voltage e of FIG. 5 is obtained at the output end of FIG. Since this voltage changes in proportion to the rotation angle θ of the carrier 2, the angle θ can be detected by measuring the magnitude from this output. As described above, in the present invention
Since the output is determined by the ratio of the width l ₁ of the magnetic signal to the length l ₀ of the MR elements R _a and R _b, a high resolution exceeding the resolution simply determined by λ can be obtained, and if λ is shortened It is possible to further increase the accuracy and resolution. Further, since there are only two output terminals, signal transmission is easy. Further, the carrier is only one track, and the magnetic sensor is simple and can be made small.

Another embodiment is shown in FIGS. 6 (A) and (B) and FIG.
FIG. 6 (A) is an example in which the width of the magnetic signal of the carrier 2 is recorded as l _m as shown in the figure. When the carrier 2 rotates, the MR elements R _a and R _b are affected by the maximum magnetic field in the vicinity of the central portion and almost no magnetic field is applied to the MR elements at both ends according to the same principle as in the previous embodiment. If connected in this way, the output voltage e becomes maximum at 0 ° and 360 ° at an angle of 180 ° as shown in FIG.

FIGS. 8 (A), (B) and FIG. 9 show another embodiment, which is a configuration for obtaining a sinusoidal output with respect to the rotation angle. If a magnetic signal having a sinusoidal magnetic signal width is recorded on the magnetic drum 2 as shown in FIG. 8 (A), the output e obtained by the connection shown in FIG. The output e is a sine wave.

10 (A) and (B) show still another embodiment. This is a magnetic medium 2A divided into two tracks A, B and both tracks A, B2.
A magnetic signal having a similar width is recorded on the disk as shown in the figure.
The magnetic signals of both tracks are recorded with a λ / 2 pitch offset, and the MR elements R _a and R _b of the magnetic sensor 3 facing them are arranged so as to be aligned in the vertical direction. With magnetic track 2
Since the relationship between the MR elements R _a and R _b is relatively the same as that of FIG. 2, the output e becomes like that of FIG. 11 by connecting them as shown in FIG.

Next, an example of increasing the output voltage is shown in FIG.
Shown in Figure 16. FIGS. 12 (A) and 12 (B) show the relationship between the carrier 2 and the magnetic sensor 3. The carrier 2 is divided into a first track A and a second track B, and the tracks A and B are shown in FIG. When the width of the magnetic signal is large, the other tracks are complementarily recorded so that the other tracks become smaller. The magnetic sensor 3 facing this is MR elements R _a and R _b at the position facing the first track A and the MR sensor at the position facing the second track B as shown.
Arrange the elements R _c and R _d . The intervals between the MR elements R _a and R _b and between R _c and R _d are λ / 2. This MR element is connected as shown in FIG. 13 or FIG. In FIG. 13, the MR elements R _a and R _b for A are connected in series to the first track, and the MR elements R _c and R _d facing the second track B are connected in series, and these are further connected in series. The connection is made to have three ends and a DC voltage V is applied to both ends to obtain an output e from the midpoint. Figure 14 shows four MR elements R _a as shown.
~ R _d is bridge-connected, voltage is applied to the feeding end and output e ₀ is obtained from the detection end. When the carrier rotates, each MR responds to this.
The resistances of the elements R _a , R _b and R _c and R _d change as shown in FIG. That is, in the width long right part of the magnetic signal in the first track A the width of the magnetic signal in the second track B is short, R _a, R _b is the amplitude varies greatly on the right side becomes a small amplitude on the left, The MR elements R _c and R _d are reversed. For this reason,
In the case of FIG. 13, the combined resistance of the MR elements R _a and R _b and R _c and R _d changes linearly as shown in FIG. Therefore, as shown in FIG. 16, the output voltage e is small when the angle θ is small, and is large when the angle θ is large.

In the case of the connection shown in FIG. 14, a series circuit of MR elements R _a and R _c and R _d and R _b is provided, and the resistance change is as shown in FIG. 15, so the outputs e ₁ and e _{2 at the} midpoint are As shown in Fig. 17, the voltage includes pulsation. However, the bridge output e ₀ becomes e ₁ −e ₂ , so
The pulsating component in the same phase disappears, both outputs are equal to zero when the angle of the carrier 2 is 180 °, and as shown in FIG. 16, e ₂ is large on the right side, so that it is a negative voltage, and on the right side, it is a positive voltage.

18 (A) and 18 (B) show the magnetic signals as shown in FIG. 12 due to the changes in FIG. 12, but the operation is exactly the same as in FIG.

19 (A) and 19 (B) are methods for obtaining a sinusoidal output, and the operation is the same as in FIG. 12, and as shown in FIG. 20, a sinusoidal output e ₀ according to the width of the magnetic signal e ₀ Is obtained. Further, when a 2-cycle width is changed in accordance with the magnetic signal of the magnetic drum 2, an output voltage of 2 cycles is obtained, and when a width of 4 cycles is changed, an output of 4 cycles is obtained.

FIG. 21 shows an example in which the magnetic sensor 3 is composed of three MR elements R ₁ , R ₂ and R ₃ . Each MR element with respect to the magnetic signal pitch λ
R ₁ , R ₂ and R ₃ are arranged λ / 3 apart. This is connected in series as shown in FIG. 22, and a fixed resistor R is connected in series, and an output is taken out from the midpoint as shown. Figure 23 shows MR
It shows the resistance change of the element. Since R ₁ , R ₂ and R ₃ are three phases with a phase difference of 120 °, if the waveform is a sine wave, the combined resistance R ₁ + R ₂ + R ₃ is a pulsating component. Disappears and changes linearly. Therefore, the output voltage e resulting from this also becomes a straight line with respect to the angle as shown in FIG.

FIG. 24 shows an example in which a linear motion is performed, and the magnetic medium 2A recording the magnetic signals N and S and the magnetic sensor 3 are opposed to each other as shown in the figure, and operates exactly as in the case of the previous rotation.

In the above description, the resistors R _a and R _b are connected in series, but the same effect can be obtained by adding the respective signals to the electric signals after conversion.

In the above-mentioned embodiment, the carrier 2 moves and the magnetic sensor 3
Are fixed, but these need only be movable. That is, the magnetic sensor 3
Alternatively, the fixed body may be provided with a magnetic medium.

〔The invention's effect〕

As described above, according to the present invention, the first and second members that move relative to each other, and a large number of small small magnetism bodies provided on the first member and recorded so as to be aligned along the relative movement direction. And a magnetoresistive effect element provided on the second member in close proximity to the magnetic recording medium so as to be sensitive to the magnetic field of the magnetic body.
And an absolute position detecting device for detecting an absolute position between the two members based on a resistance change of the magnetoresistive effect element that changes due to a relative movement of the first member. The magnetic poles and the N magnetic poles are arranged along the arranging direction of the small magnetic bodies, and the small magnetic bodies are arranged so that the magnetic poles of the adjacent small magnetic bodies have the same polarity. A small magnet is formed so that the width in the direction changes depending on the position in the relative movement direction, and the longitudinal direction of the magnetoresistive effect element is arranged so as to be orthogonal to the arrangement direction of the small magnets. There is an absolute position detector.

 This configuration has the following advantages.

(1). Since the small magnets are arranged so that the magnetic poles of adjacent small magnets have the same polarity as each other, the magnetic flux that the magnetoresistive effect element is sensitive to becomes larger than that of the adjacent magnetic poles of different polarities. The detection output of the resistance effect element increases.

(2). The small magnetic body is formed so that the width length in the direction perpendicular to the arrangement direction of the small magnetic body changes depending on the position in the relative movement direction, and the longitudinal direction of the magnetoresistive effect element is arranged so as to be orthogonal to the arrangement direction of the small magnetic body. Therefore, the detection output of the magnetoresistive effect element changes due to the difference in the width of the small magnet. The position of the first member and the second member can be detected by the change in the detection output.

[Brief description of drawings]

FIG. 1 is a perspective view of an apparatus implementing the present invention, FIGS. 2 (A) and 2 (B) are views showing the relationship between the magnetic sensor of the present invention and a magnetic medium, and FIG. 3 is an MR element used in the present invention. FIG. 4 is a characteristic diagram, FIG. 4 is a connection diagram, FIG. 5 is a waveform diagram for explaining the operation of the present invention, and FIG.
7A and 7B are diagrams showing the relationship between the magnetic medium and the magnetic sensor of another embodiment, FIG. 7 is the output waveform diagram of FIG. 6, and FIG.
FIGS. 9A and 9B are views showing a relationship between a magnetic medium and a magnetic sensor according to another embodiment, and FIG. 9 is an output waveform diagram thereof.
10 (A) and 10 (B) are views showing the relationship between the magnetic medium and the magnetic sensor according to another embodiment, FIG. 11 is its output waveform diagram, and FIGS. 12 (A) and 12 (B) are the same. FIG. 13 is a diagram showing the relationship between a magnetic medium and a magnetic sensor according to another embodiment, FIGS. 13 and 14 are connection diagrams thereof, FIG. 15 is an explanatory waveform diagram of FIG. 12, and FIG. 16 is a diagram of FIG. Output waveform diagram, Fig. 17 is the output waveform diagram of Fig. 14, Fig.
Figures 18 (A) and (B), and Figures 19 (A) and (B) are shown in Figure 12.
FIG. 20 is a diagram showing a modified example of the diagram showing the relationship between the magnetic medium and the magnetic sensor, FIG. 20 is an output waveform diagram of FIG. 19, and FIG. 21 is a still further embodiment of the present invention showing the magnetic medium. FIG. 22 is a connection diagram of the magnetic sensor, FIG. 22 is a connection diagram of FIG. 21, FIG. 23 is an explanatory waveform diagram of FIG. 21, and FIG. 24 is a perspective view when the present invention is applied to a linearly moving embodiment. is there. 1 ... Rotary axis, 2 ... Carrier, 2A ... Magnetic medium, N, S ...
... Small magnetic body magnetic pole, 3 ... Magnetic sensor, λ ... Magnetic signal pitch, R _a , R _b , R _c , R _d , R ₁ , R ₂ , R ₃ ...... MR element, R ...... Fixed resistance Or MR element that does not receive magnetic field, V power supply, 20 ... Magnetic signal non-recording section, 21 ... Magnetic signal recording section.

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP 62-47501 (JP, A) JP 62-24110 (JP, A) JP 51-2446 (JP, A) JP 63- 206613 (JP, A)

Claims (1)

(57) [Claims] 1. A magnetic recording medium having first and second members that move relative to each other, and a large number of small magnetic particles provided on the first member and recorded so as to be aligned along the relative movement direction. And a magnetoresistive effect element provided on the second member so as to be close to the magnetic recording medium so as to be sensitive to the magnetic field of the magnetic body, and change by relative movement of the first member and the first member. In the absolute position detection device for detecting the absolute position between the two members based on the resistance change of the magnetoresistive element, a pair of S magnetic poles and N magnetic poles formed on the small magnetic body are arranged in the small magnetic body. The small magnets are arranged so that the magnetic poles of the adjacent small magnets have the same polarity as each other, and the width length in the direction perpendicular to the arrangement direction of the small magnets is the position in the relative movement direction. Changed by To form a small magnetism generation body in so that the absolute position detecting device characterized by longitudinal direction is arranged so as to be perpendicular to the arrangement direction of the small onset magnetized body of the magnetoresistive element.