JP2529960B2 - Magnetic position detector - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a position detecting device, and more particularly, to an improvement of a magnetic position detecting device that magnetically detects a position to obtain a sine wave output. .

Further supplementing, the present invention is directed to high resolution,
For example, the present invention relates to a magnetic position detecting device that is used for speed control of an NC machine tool that processes a sine wave output circuit, and more specifically, for example, when detecting the position of a rotating device to perform speed control, The present invention relates to a magnetic position detecting device capable of removing harmonic distortion with respect to a fundamental wave.

[Conventional technology]

In the field of precision equipment, a so-called magnetic position detection device composed of a magnetic medium and a magnetic sensor is used to detect the position of, for example, a rotating device.
Highly accurate and highly reliable measurement is required.

Further, in order to improve the accuracy of speed control, a direct drive without a reducer (gear) between the motor and the load is required.

That is, in a precision machine such as an NC machine tool, the uneven rotation of the rotating body directly relates to the quality of the product, and therefore low speed rotation with less uneven rotation is required.

Therefore, the magnetic sensor used for such speed control is required to have high resolution and high accuracy.

In other words, since a microcomputer is used for the speed control described above, a magnetic sensor with high resolution and high accuracy is used to change the position within a certain reference time or the ratio of the time change to a certain position change. The speed is controlled by obtaining the speed.

One way to improve the resolution of the magnetic sensor is to increase the number of output cycles per rotation of the rotating drum that generates a magnetic field. The length of the signal N-S becomes shorter and has a limit [for example, the diameter of the rotating drum (unit:
mm) is φ50, 3000 cycles is the quantitative limit].

On the other hand, one cycle of the sine wave is subdivided to obtain position information for each position, and the resolution in one cycle of the sine wave thus obtained is Y If X is the number of output cycles of, the resolution of the magnetic sensor as a whole becomes a very large value of X × Y (By the way, a sine wave output of several hundred cycles or more is obtained for one rotation of the rotary drum, If the output of is further divided in analog to improve the resolution, for example, if the analog division is 8 bits, the resolution per rotation will be 256 × several hundreds, and high resolution will be obtained). If it is used, it is possible to obtain a system with less uneven rotation even at low speed. Of course, depending on the application, the former, that is, the number of output cycles per rotation of the rotating drum that generates a magnetic field, can be set. Using the increased one is fine, but the latter is suitable for use when very high resolution is required.

A conventional technique relating to the magnetic position detecting device is described in, for example, Japanese Patent Publication No. 60-45804.

[Problems to be solved by the invention]

By the way, a magnetoresistive effect element (hereinafter, abbreviated as MR element) is changed by a magnetic field lateral to the longitudinal direction, which is shown in FIG.

As shown in FIG. 4, when the input magnetic field of the magnetic medium is increased, the resistance of the MR element decreases, but the resistance saturates at a certain value.

In addition, the maximum amount of this resistance change is about 2 times the resistance of the MR element.
Very small, ~ 3%.

For this reason, in order to obtain as large an output as possible with a magnetic sensor, it is advantageous to change the input magnetic field of the magnetic medium sufficiently from zero to the point where the magnetic field saturates. I am trying to use.

On the other hand, the relationship between the magnetic sensor composed of the MR element and the rotating drum that generates the magnetic field is arranged via a spacing lg as shown in FIG.

Here, the magnitude of the magnetic field applied to the MR element depends on the magnetic characteristics of the magnetic paint, the pitch λ of the signal magnetic fields N and S, the spacing lg, and the like. Particularly, the spacing lg is an important factor in manufacturing and assembling the rotating drum of the same specifications.

That is, the magnitude of the magnetic field applied to the MR element largely changes depending on the magnitude of the spacing lg.

Then, when the spacing lg is large, the input magnetic field of the magnetic medium is small, and the resistance change of the obtained MR element is also small, so that the output of the magnetic sensor is reduced.

However, in this case, since the MR element resistance saturation point is not used, a sinusoidal wave without distortion can be obtained as the output waveform (this state is shown in B of FIG. 15). The B range with a large lg was used.

However, in the range of B, although a sine wave is obtained, the output amplitude is small, and when the spacing lg changes, the output abruptly changes, causing a large fluctuation due to eccentricity of the rotating drum and the like.

On the other hand, in the range C of FIG. 15, the output is large and the change of the fundamental wave component is small with respect to the change of the spacing lg. Therefore, the influence of the eccentricity of the rotating drum can be ignored. By using the range of C, the output is large, the change of the fundamental wave component with respect to the change of the spacing lg is small, and the influence of the eccentricity of the rotating drum or the like can be ignored.

However, in the range of C, since the vicinity of magnetic saturation of the MR element is used, harmonic distortion will occur in the output.

The reason is that the range of C including the range of A in FIG. 15 is caused by the small spacing lg, and when harmonic distortion occurs, it is output with the high resolution of X × Y described above. An error also occurs in the signal, which hinders accurate speed control.

Note that it is easy to cancel out even harmonic components of the frequency components of the AC distortion wave contained in the output signal, as is well known in the art.

An object of the present invention is to provide a magnetic position detection device aiming for high resolution, in which an amplitude change with respect to a spacing change is small, a large output is obtained as an output signal, and an odd harmonic component due to saturation of resistance change is removed. Will be
An object of the present invention is to provide an improved magnetic position detecting device capable of obtaining a sinusoidal component with little distortion.

[Means for solving problems]

The present invention is provided on one of a moving body and a fixed body,
Further, a large number of small magnetic field magnetic poles are continuously arranged at a predetermined interval so as to be aligned along the moving direction, and one of the fixed body or the movable body is provided so as to face the small magnetic field magnetic poles. And a plurality of magnetoresistive effect elements that are sensitive to the signal magnetic field of the small magnetic pole for signal magnetic field and change so that the internal resistance decreases as the signal magnetic field increases, and the longitudinal direction of the magnetoresistive effect element is The magnetoresistive effect elements are arranged so as to be orthogonal to the arrangement direction of the small magnetic poles for the signal magnetic field, and the plurality of magnetoresistive effect elements are arranged in parallel with each other at intervals, and the internal resistance of the plurality of magnetoresistive effect elements In a magnetic position detecting device for detecting the position of a moving body or a fixed body based on an electrical output signal due to a change, the signal magnetic field sensitive to the magnetoresistive effect element is increased. The magnetoresistive effect element is arranged close to the small magnetic pole for the signal magnetic field so that a resistance change saturation state in which the decrease of the internal resistance is slowed down is brought about, and at least one odd number with respect to the output fundamental wave of the output signal A magnetic position detecting device is characterized in that a plurality of magnetoresistive effect elements are arranged at intervals P as described below so as to cancel and cancel harmonic components in opposite phases.

λ: interval between small magnetic poles for signal magnetic field k: odd harmonic order n: integer m: odd number (except when matching with k) [Operation] According to the present invention having the above configuration, high resolution is achieved. In a magnetic position detection device that aims at, a small amplitude change with respect to a spacing change, a large output can be obtained as an output signal, and an odd harmonic component due to saturation of resistance change is removed. Can be obtained.

〔Example〕

The present invention will be described below with reference to an embodiment shown in FIGS. 1 to 5, in which FIG. 1 is an explanatory view of a combination of a magnetic medium 3 and a magnetic sensor 4, and FIG. 2 is a magnetic diagram shown in FIG. FIG. 3 is a developed view of the medium 3, FIG. 3 is an electric circuit diagram of the magnetic sensor 4 shown in FIGS. 1 and 2, and FIG. 4 is a magnetoresistive effect element constituting the magnetic sensor 4 shown in FIGS. An operation characteristic diagram of (MR element), and FIG. 5 are various signal waveform diagrams obtained by the position detecting device shown in FIGS. 1 and 2.

In FIG. 1 showing the engagement between the magnetic medium 3 and the magnetic sensor 4, a rotary drum 2 is fixed to a moving body such as a rotary shaft 1, and a magnetic signal is recorded on the outer circumference of the rotary drum 2 at a pitch λ. A magnetic medium 3 having a so-called magnetic pole 31
Is arranged. The magnetic medium 3 is, for example, a ferromagnetic material or a permanent magnet, or a magnetic powder hardened with resin to form a magnetic pole.
It is formed by magnetizing 31. Facing the magnetic medium 3,
A magnetic sensor 4 in which MR elements are arranged at a predetermined interval is fixed to the magnetic medium 3 with a spacing lg. In the figure, reference numeral 41 indicates a sensor substrate.

In FIG. 2 which is a development view of the magnetic medium 3 shown in FIG. 1, the magnetic poles N and S are recorded at the recording pitch λ on the magnetic medium 3 as described above. The magnetic sensor 4 has MR elements R ₁₁ and R
₁₂ , R ₁₃ , R ₁₄ , R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , R ₁₁ and R ₁₂ ,, R ₁₃
And R ₁₄ , R ₂₁ and R ₂₂ , R ₂₃ and R ₂₄ are respectively separated by λ / 10, and R ₁₁ and R ₁₃ , R ₂₁ and R ₂₃ are respectively separated by λ / 6. There is. Also, R ₁₁ and R ₂₁ , R ₁₂ and R ₂₂ , R ₁₃
R ₂₃ , R ₁₄ and R ₂₄ are arranged apart from each other by λ / 2.
In FIG. 3, among the MR elements described above, R ₁₁
And R ₂₁ , R ₁₂ and R ₂₂ , R ₁₃ and R ₂₃ , R ₁₄ and R ₂₄ are connected in series, and both ends of each are connected to the power supply V. Further, the midpoints a, b, c, d of the MR elements connected in series are respectively connected to the negative input of the differential amplifier OPA via the resistors R _i . A feedback resistor R _f is connected between the output P ₀ and the negative input of the differential amplifier OPA. The positive input of the differential amplifier OPA, a voltage V _R is applied. Therefore, the signals of the outputs a, b, c, d of each MR element are added together and amplified, and appear at the output terminal P ₀ of the differential amplifier OPA. The MR element of the magnetic sensor 4 changes its electric resistance with respect to a magnetic field.
It is made by depositing a thin film of ferromagnetic material NiFe or NiCo on the surface of glass or the like. As shown in FIG. 4, the resistance change with respect to the magnetic field changes in proportion to the magnitude of the magnetic field regardless of the direction of the magnetic field. However, with respect to the magnitude of the magnetic field, the resistance change is saturated at a certain value. Now, when the rotary drum 2 shown in Figure 1 is the magnetic medium 3 is moved by rotating, assuming the magnetic field of the magnetic pole 31 is changed as the input field of FIG. 4, the resistance of the MR element R ₁₁ is first It changes as shown in Fig. 5 (1). In addition, MR element R ₂₁
Is placed λ / 2 away from R ₁₁ , so MR element R ₁₁
The phase is delayed by λ / 2 with respect to the resistance change, and R _{21 in} Fig. 5 (1)
It changes like. Then, MR elements R ₁₁ and R shown in FIG.
The output voltage v _{a0 at} the midpoint a of ₂₁ becomes a distorted waveform as shown by the solid line in FIG. 5 (a), and this waveform is the fundamental wave v _{a1 of the} broken line.
In addition, the third harmonic wave v _a3 and the fifth harmonic wave v _a5 are included. Then, MR element R ₁₂ and R ₂₂ are, to R _11, R _21, because it is arranged offset respectively lambda / 10 position, R ₁₂ and R
Phase of the voltage obtained from the output terminal b of _22, v _a0 than lambda /
It becomes v _b0 in FIG. Similarly, MR
The output voltage v _c0 due to the elements R ₁₃ and R ₂₃ , and further the output voltage v _d0 due to R ₁₄ and R ₂₄ are respectively λ / 6 and v 6 with _respect to v _a0 as shown in FIGS. 5 (c) and (d). It has a phase difference of λ / 6 + λ / 10. Further, the outputs v _b0 , v _c0 , v _d0 are v _a0
And the fundamental wave v _b1 , v _c1 , v _d1 , respectively, the third harmonic wave v _b3 , v _c3 , v _d3 and the fifth harmonic wave v _b5 ,
It contains v _c5 and v _d5 respectively. Focusing on each of these waveforms, the fifth harmonic v _a5 of the output voltage v _a0 shown in FIG. 5 (a) and the fifth harmonic of the output voltage v _b0 shown in FIG. 5 (b).
v _b5 is out of phase, and therefore adding v _a0 and v _{b0 cancels} the fifth high frequency. Also, comparing the output voltages v _c0 and v _d0 in FIGS. 5 (c) and 5 (d),
The order components v _c5 and v _d5 are in anti-phase, so adding v _c0 and v _d0 cancels the fifth order component. Further, considering the third harmonic, the third component v _a3 of the output voltage v _a0 shown in FIG. 5 (a) and the third component v _c3 of the output voltage v _c0 shown in FIG. 5 (c). Is the opposite phase, and the third-order component v of the output voltage v _b0 shown in FIG.
_b3 third order component v _d3 of the output voltage v _d0 shown in FIG. 5 (d) is also in phase opposition. Therefore, FIG. 5 (a), (b),
By adding the four signals v _a0 , v _b0 , v _c0 , v _d0 of (c) and (d), it becomes possible to cancel the fifth and third harmonics, and the remaining four fundamental waves v _a1,, v _b1 , v _c1 ,
If v _d1 is added by the differential amplifier OPA of FIG. 3, a sine wave output v ₀ as shown in FIG. 5 (2) can be obtained at its output terminal P _0, which is apparent from the above description. Like, MR
The waveform distortion of the magnetic sensor 4 caused by element saturation can be canceled. Also, the output change of the fundamental wave component with respect to the spacing change between the MR element incorporated in the magnetic sensor 4 and the magnetic medium 3 is as shown by the broken line in FIG. When used in this range, the output fluctuation with respect to the spacing becomes extremely small.

6 and 7 are both electric circuit diagrams showing the magnetic sensor 4 of FIGS. 1 and 2 in a connection mode different from that of FIG. 3. In FIG. 6, MR elements R ₁₁ and R are shown. ₁₂ , R ₁₃ , R ₁₄ and R
₂₁ , R ₂₂ , R ₂₃ , and R ₂₄ are connected in series, both ends thereof are connected in series to the power source V, and the output terminal P ₀ is provided at the middle point. Further, in FIG. 7, MR elements R ₁₁ , R ₁₂ , R ₁₃ , R ₁₄ , R ₂₁ , R
₂₂ , R ₂₃ and R ₂₄ are respectively connected in parallel and are connected in series to a power source V, and an output terminal P ₀ is provided at the midpoint thereof. Then, the MR elements R ₁₁ , R ₁₂ shown in FIG. 6 and FIG.
The resistance change of R ₁₃ and R ₁₄ is as shown in Fig. 8 (1) due to the same phase difference as the element arrangement, but each resistance change contains many odd harmonics. Has been. However, the combined resistance R ₁ in which these four MR elements are connected in series or in parallel has a waveform in which the odd harmonic components are canceled, as shown in FIG. 8 (2). Also, MR element R
_Since the resistance changes of ₂₁ , R ₂₂ , R ₂₃ , and R ₂₄ are arranged with the phase shifted by λ / 2 from the resistance changes of R _{11 to} R ₁₄ , the combined resistance R ₂ is different from R _1. R _{2 in} Fig. 8 (3) with a λ / 2 phase shift
It becomes a waveform like. Therefore, the waveform of the output voltage obtained from the output terminal P _{0 of} FIGS. 6 and 7 becomes the fundamental wave output v ₀ of FIG. 8 (4) with no harmonic component. And
According to the connection examples shown in FIGS. 6 and 7, it is possible to obtain a sine wave with less distortion only by connecting the MR element without using the differential amplifier OPA shown in FIG.

9 (a) to (d) are shown in FIG. 1 and FIG.
This is an example of bridge connection of MR elements. FIG. 9 (a) shows
The MR elements R ₁₁ and R ₁₃ , R ₂₂ and R ₂₄ connected in series are connected in series to the power source V, and the terminal e ₁ is taken out from the midpoint. Similarly, MR elements R ₂₁ and R ₂₃ , R ₁₂ and R ₁₄
Those connected in series are connected in series to the power source V, and the terminal output e ₂ is taken out from the midpoint. Here, the combination of MR elements on each side of the bridge R ₁₁ and R ₁₃ , R
₂₂ and R ₂₄ , R ₂₁ and R ₂₃ , R ₁₂ and R ₁₄ are displaced from each other by λ / 6 position, and operate so as to cancel the third harmonic. Next, R ₁₁ and R ₂₂ , R ₁₃ and R ₂₄ are respectively There is a phase difference of, and it operates so as to cancel the fifth harmonic. Therefore, the voltage appearing at the output terminal e ₁ is only the fundamental wave in which the third and fifth harmonics are canceled. Similarly, since the MR elements R ₂₁ and R ₁₂ , and R ₂₃ and R ₁₄ are also arranged to cancel the fifth harmonic, the output terminal e ₂ also has no third and fifth harmonic components. The output of e ₁ gives the output of the fundamental wave with a λ / 2 phase difference. Therefore, according to the bridge connection described above, a sine wave output can be obtained. The connection shown in FIG. 9 (b) is opposite to that shown in FIG. 9 (a), and the two MR elements R ₁₁ and R ₁₂ , R ₂₃ and R ₂₄ , R ₂₁ and R ₂₂ and R _{13 on} each side of the bridge are connected. R ₁₄
In this example, the fifth harmonic is canceled, and the third harmonic is canceled at the place where it is connected in series to the power supply V. Fig. 9 (c)
Is each side of the bridge, namely R ₁₁ and R ₁₃ , R ₂₁ and R ₂₃ , R ₂₂ ,
The third harmonic is canceled by R ₂₄ , R ₁₂ , and R ₁₄ , and the output terminals e ₅ and e ₆ each include a fifth harmonic component. This fifth harmonic component is Since the same phase appears in e ₅ and e ₆ , the fifth harmonic is canceled as the bridge output. 9 (d) is the reverse of FIG. 9 (c), in which the fifth harmonic is canceled at each bridge side, and the third harmonic is canceled at the bridge output to obtain a sine wave output.

In summary, in the case of the embodiment described with reference to FIGS. 1 to 9, the harmonic order is k as a general expression,
If the pitch of NS of the signal magnetic field is λ, n is an integer, and m is an odd number, It can be seen that the MR elements may be arranged apart from each other.

FIG. 10 is an explanatory view of the combination of the magnetic medium 3 and the magnetic sensor 4 showing another embodiment of the magnetic position detecting device according to the present invention, and FIG.
The drawing is an electric circuit diagram of the magnetic sensor 4 shown in FIG. 10. In the present embodiment, the case where four MR elements cancel the fifth and third harmonics is shown.

In FIG. 10 showing the connection between the magnetic medium 3 and the magnetic sensor 4, the magnetic sensor 4 is composed of MR elements R ₁₁ , R ₁₂ , R ₂₁ and R ₂₂ , and for the MR element R ₁₁ , R ₁₂ is λ / They are placed 6 apart, and the R ₂₁ They are placed apart. Furthermore, R ₂₁ and R ₂₂ are placed λ / 6 apart. Then, in FIG. 11, the above-mentioned 4
Of the MR elements, R ₁₁ and R ₂₁ , R ₁₂ and R ₂₂ are connected in series to the power supply, and the output is obtained from the midpoints a ₁ and a ₂ and added together by the differential amplifier OPA2. From terminal P ₀₁ . MR
The elements R ₁₁ and R ₂₁ , R ₁₂ and R ₂₂ are respectively , And therefore operates to cancel the fifth harmonic. Further, R ₁₁ and R ₁₂ , and R ₂₁ and R ₂₂ have a λ / 6 phase difference, and therefore operate to cancel the third harmonic, and as a result, the third and third harmonics are output from the terminal P _0f . It is possible to obtain an output without the fifth harmonic.

12 (a) and 12 (b) are both electric circuit diagrams showing the magnetic sensor 4 of FIG. 10 in a connection mode different from that of FIG. 11, and FIG. 12 (a) is shown in FIG. This is an example of bridge connection of MR elements. Then, according to the connection example shown in FIG. 12 (a), the waveforms in which the fifth harmonics are canceled by the MR elements R ₁₁ and R ₂₁ and R ₂₂ and R ₁₂ are obtained from the output terminals e ₉ and e ₁₀ , respectively. To be Further, in FIG. 12 (a), MR elements R ₁₁ and R
₂₂ and R ₂₁ and R ₁₂ cancel the third harmonic, respectively, so that a sinusoidal output is obtained at the bridge output. FIG. 12 (b) shows MR elements R ₁₁ and R ₁₂ , R ₂₁ and R _22.
Are connected in series to the power supply V, cancel out the third harmonics on each side, and the fifth side is above and below the output terminal P ₀₂ , that is, at R ₁₁ , R ₁₂ and R ₂₁ , R ₂₂ . Since the second harmonic is canceled, a sine wave output is obtained at the output terminal P ₀₂ .

Figure 13 and Figure 14 is a Togo explanatory view of the magnetic medium 3 and the magnetic sensor 4 showing still another embodiment of the magnetic position detecting apparatus according to the present invention, respectively, FIG. 13 and MR element R ₁₁
R ₁₂ , R ₂₁ and R ₂₂ are separated by λ / 10, R ₁₁ and R ₂₁ , R ₁₂ and R ₂₂
Is an example in which they are arranged at a distance of λ / 2 + λ / 6. And thirteenth
The wiring mode of the MR element shown in the figure may be the same as in the case of FIG. 11 and FIG. 12, and it can be considered that the third harmonic and the fifth harmonic in the embodiment of FIG. 10 are exchanged. it can. That is, this, referring to the circuit of Figure 11, the magnetic sensor 4 of FIG. 13 is a third harmonic wave and R ₁₁ R
₂₁ and R ₁₂ and R ₂₂ cancel each other, and operate so as to cancel the fifth harmonic wave, which is the signal of the output a _{1 and} the signal of a ₂ . Also,
When the magnetic sensor 4 of FIG. 13 is connected as shown in FIG. 12 (a), the magnetic sensor 4 of FIG. 13 has MR elements R ₁₁ and R ₂₁ and R ₂₂ and R ₁₂ which are the third harmonics. Is canceled, and the fifth harmonic is canceled by the bridge output. Furthermore, when the magnetic sensor 4 of FIG. 13 is connected as shown in FIG.
The magnetic sensor 4 shown in the figure cancels the fifth harmonic with the MR elements R ₁₁ and R ₁₂ and R ₂₁ and R ₂₂ , and above and below the output terminal P ₀₂ , that is, the MR elements R ₁₁ , R ₁₂ and R ₂₁ and R _22. Cancels the 3rd harmonic.

On the other hand, FIG. 14 shows a case in which not only the third and fifth harmonics but also the seventh harmonic are mixed in the output of the magnetic sensor 4 and the third harmonics are canceled at the same time. Illustrated. Then, in FIG. 14, MR elements R ₁₁ , R ₁₂ , R ₁₃ ,
The arrangement between R ₁₄ , and further the arrangement between R ₂₁ , R ₂₂ , R ₂₃ , and R ₂₄ are the same as in the case of FIG. But R ₁₁ and R ₂₁ , R ₁₂ and R ₂₂ ,
The intervals between R ₁₃ and R ₂₃ , R ₁₄ and R ₂₄ are as shown in the figure. They are located apart from each other. Here, the magnetic sensor 4 arranged as described above is connected as shown in FIG.
₁₁ and R ₂₁ , R ₁₂ and R ₂₂ , R ₁₃ and R ₂₃ , R ₁₄ and R ₂₄ output terminals a, b,
Consider the outputs of c and d. The 7th harmonic component due to MR element R ₁₁ and the 7th harmonic component due to R ₂₁ are just in opposite phase, and from the output v _{a0 at} point a in Fig. 3, the 7th harmonic component Is canceled. Similarly, R ₁₂ and R ₂₂ , R ₁₃ and R ₂₃ , R ₁₄ and R
_From the relationship of ₂₄ , each output v _b0 , v _c0 , v _{d0 at} point b, c, d becomes like v _b0 , v _c0 , v _d0 in Fig. 5 that does not include the 7th harmonic component. . Therefore, at the output terminal P ₀ in FIG. 3, a sine wave output in which the third and fifth harmonics are canceled is obtained as described in FIG. When the magnetic sensor 4 of FIG. 14 is connected as shown in FIGS. 6 and 7, the output terminal
Upper MR element R ₁₁ , R ₁₂ , R ₁₃ , R _{14 of} P ₀ and lower MR element R ₂₁ , R ₂₂ , R
₂₃ and R ₂₄ are respectively Since they are placed apart, they are out of phase with respect to the 7th harmonic, so the 7th harmonic does not appear at its output, and the 3rd and 5th harmonics have the second harmonic. It operates in the same way as described in the figure and cancels these third and fifth harmonics, so that its output v ₀ is
A sine wave output can be obtained. Similarly, when the magnetic sensor 4 of FIG. 14 is connected as shown in FIG. 9 (a), each side of the bridge R ₁₁ and R ₁₃ , R ₂₂ and R ₂₄ , R ₂₁ and R ₂₃ and R ₁₂ The third harmonic is canceled by R ₁₄ , and R ₁₁ , R ₁₃ and R ₁₂ , R ₁₄ and R ₂₁ , R
The 5th harmonic is canceled by ₂₃ , R ₂₂ and R ₂₄ . In addition, R ₁₁ , R
The seventh harmonic is canceled by ₁₂ , R ₁₃ , R ₁₄ and R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ . In addition, the magnetic sensor 4 shown in FIG.
Even in the case of the bridge connection as in (c) and (d), the same operation is performed, and the third and fifth harmonics, and further the seventh harmonic
It is possible to cancel the second harmonic and obtain a sine wave output at its output.

As described above, if the condition that the phases of the respective harmonics are opposite phases is satisfied, the intended purpose to be achieved by the present invention can be achieved. In the illustrated embodiment, the third
In order to cancel the second harmonic, it is basically necessary to shift the MR element by λ / 6. If n is an integer and m is an odd number, (n ± m /
6) It can be seen that the MR element can be arranged by shifting the λ position. The same can be said for the fifth and seventh harmonics in the case of the illustrated embodiment, which is the same as the embodiment described with reference to FIGS. 1 to 9 above. Including the embodiments described with reference to FIGS. 10 to 14, as a general formula, if the harmonic order is k, It can be seen that the MR elements may be arranged apart from each other.

In the illustrated embodiment, as shown in FIG.
Although the case where the rotating drum is used as the moving body 1 has been illustrated, there is no problem in molding this rotating drum with a plastic magnet, and a rotating disk may be used instead of the rotating drum. Furthermore, in the illustrated embodiment, the case where the position of the rotating body is detected has been illustrated, but the device of the present invention can also be used for detecting the position of a linearly moving device in addition to the rotating body.

〔The invention's effect〕

As described above, the present invention is provided on one of the moving body or the fixed body, and a large number of small magnetic fields for signal magnetic fields continuously arranged at a predetermined interval so as to be arranged along the moving direction, It is provided on one of the fixed body or the moving body so as to face the small magnetic pole for signal magnetic field, and the internal resistance decreases as the signal magnetic field increases in response to the signal magnetic field of the small magnetic pole for signal magnetic field. A plurality of magnetoresistive effect elements, the longitudinal direction of the magnetic field effect element is orthogonal to the arrangement direction of the small magnetic poles for the signal magnetic field, and the plurality of magnetoresistive effect elements are spaced from each other. A magnetic position detecting device in which magnetoresistive effect elements are arranged in parallel and the position of a moving body or a fixed body is detected based on an electrical output signal due to changes in internal resistance of a plurality of magnetoresistive effect elements. In, when the signal magnetic field sensed by the magnetoresistive effect element becomes large, the magnetoresistive effect element is placed close to the small magnetic pole for the signal magnetic field so that a resistance change saturation state in which the decrease in internal resistance is slowed down is brought about. Magnetic position in which a plurality of magnetoresistive effect elements are arranged at the following intervals P so as to cancel and cancel at least one odd harmonic component with respect to the output fundamental wave of the output signal in opposite phases. It is in the detector.

λ: spacing between small magnetic poles for signal magnetic field k: odd harmonic order n: integer m: odd number (except when k matches) And according to the present invention, a magnetic position detecting device aiming at high resolution. , There is little change in amplitude with respect to spacing, and a large output is obtained as an output signal.
Moreover, it is possible to obtain a sinusoidal wave component with less distortion, in which odd harmonic components due to saturation of resistance change are removed.

[Brief description of drawings]

FIG. 1 is an explanatory view of a combination of a magnetic medium 3 and a magnetic sensor 4 showing an embodiment of a magnetic position detecting device according to the present invention, and FIG. 2 is a development view of the magnetic medium 3 shown in FIG. 1 is an electric circuit diagram of the magnetic sensor 4 shown in FIGS. 1 and 2, and FIG. 4 is an operating characteristic line of a magnetoresistive effect element (MR element) constituting the magnetic sensor 4 shown in FIGS. 1 and 2. FIGS. 5 and 5 are various signal waveform diagrams obtained by the position detecting device shown in FIGS. 1 and 2, and FIGS. 6 and 7 show the magnetic sensor 4 shown in FIGS. An electric circuit diagram shown in a connection mode different from that of FIG. 3, FIG. 8 is a waveform diagram of various signals obtained by the electric connection shown in FIGS. 6 and 7, and FIG. 9 is FIG. 1 and FIG.
FIG. 10 is an electric circuit diagram showing the magnetic sensor 4 shown in FIG. 3, 6, and 7 in a connection mode different from that shown in FIGS. 3, 6 and 7, and FIG. 10 is a magnetic medium showing another embodiment of the magnetic position detecting device according to the present invention. 11 is an electric circuit diagram of the magnetic sensor shown in FIG. 10, and FIG. 12 is an electric circuit diagram showing the magnetic sensor 4 of FIG. 10 in a connection mode different from that of FIG. Circuit diagram, Figure 13 and Figure
FIG. 14 is an explanatory view of the combination of the magnetic medium 3 and the magnetic sensor 4 showing still another embodiment of the magnetic position detecting device according to the present invention, and FIG. 15 is an output voltage characteristic with respect to spacing of the magnetic position detecting device. It is a diagram. 2 ... Moving body (rotating drum), 3 ... Magnetic medium (small magnetic pole for signal magnetic field), 4 ... Magnetic sensor.

Front page continuation (72) Inventor Shoichi Kawamata 4026 Kujimachi, Hitachi City Hitachi Ltd. Hitachi Research Laboratory (56) References JP-A-60-29611 (JP, A) JP-A-60-135768 (JP , A)

Claims (1)

(57) [Claims] 1. A movable body or a fixed body, which is provided
Further, a large number of small magnetic field magnetic poles are continuously arranged at a predetermined interval so as to be aligned along the moving direction, and one of the fixed body or the movable body is provided so as to face the small magnetic field magnetic poles. And a plurality of magnetoresistive effect elements that are sensitive to the signal magnetic field of the small magnetic pole for signal magnetic field and change so that the internal resistance decreases as the signal magnetic field increases, and the longitudinal direction of the magnetoresistive effect element is The magnetoresistive effect elements are arranged so as to be orthogonal to the arrangement direction of the small magnetic poles for the signal magnetic field, and the plurality of magnetoresistive effect elements are arranged in parallel with each other at intervals, and the internal resistance of the plurality of magnetoresistive effect elements In a magnetic position detecting device for detecting the position of a moving body or a fixed body based on an electric output signal due to a change, the signal magnetic field sensitive to the magnetoresistive effect element becomes large. By the way, the magnetoresistive effect element is arranged close to the small magnetic pole for the signal magnetic field so as to bring about a resistance change saturation state in which the decrease of the internal resistance becomes dull, and at least one odd harmonic of the output fundamental wave of the output signal is arranged. A magnetic position detecting device characterized in that a plurality of magnetoresistive effect elements are arranged at an interval P as described below so as to cancel and cancel wave components in mutually opposite phases. λ: Interval between small magnetic poles for signal magnetic field k: Odd harmonic order n: Integer m: Odd (However, when it matches with k)