JPS6117002A - Device for magnetically detecting position - Google Patents

Abstract

PURPOSE:To conduct detection with the same sensitivity and without any magnetic interference even from each magnetized track bearing magnetic signals different in record length from others, by providing magnetic signal elements bearing magnetic record units being continuous in required numbers in the direction of movement of a moving body and non-magnetic-field elements bearing no magnetic record units. CONSTITUTION:A rotary drum 5 fitted to a rotary body 1 through the intermediary of a rotary shaft 2 has magnetized tracks M0a-M3a which are prepared by recording magnetic signals in different record length on a magnetic recording medium on the surface of the drum, and a magnetic sensor 4a having magnetoresistance elements R01- R32 disposed thereon is provided opposite to the drum. Each track is provided with magnetic signal elements bearing magnetic poles of minimum magnetic record units which have polarities of N or S and are continuous in required numbers in the direction of movement of the drum indicated by an arrow, and with non-magnetic-field elements bearing no magnetic record units, and by this construction, magnetic detection signals are obtained. According to this constitution, magnetic signals can be detected with the same sensitivity and without any magnetic interference from each magnetized track even when it bears the signals different in record length from others.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an apparatus for magnetically detecting position.

[Background of the invention]

Regarding this device, for example, JP-A-54-1
An angle detector such as that described in Publication No. 18259 belongs to the public domain, and the technique described in this publication is based on the principle described below.

That is, FIG. 14 is a configuration diagram of a known example of an angle detector, FIG. 15 (A) is a developed view of a rotating drum, and FIG.
16 is a plan view of the magnetic sensor, and FIG. 16 is a resistance change waveform diagram of the magnetoresistive element.

In FIGS. 14 to 16, 1 is a rotating body related to the rotating body to be detected, 2 is a rotating shaft, 3 is a mounting base, 4 is a magnetic sensor having each magnetic detection element, and 5 is a magnetized track M. −
In the rotating drum made up of M2, Ro-R2 is a magnetoresistive element related to a magnetic detection element.

Accordingly, in this example, as shown in FIG.
A plurality of magnetized tracks M recorded at different recording wavelengths, N and S. - a rotating drum 5 having M2 and the rotating body 1;
is attached by the mounting base 3 to the magnetized track M0~
It is composed of magnetic sensors 4 each placed close to M2, and the magnetic signal is sent to the magnetoresistive element R.
o-R2 is used to extract a resistance change as shown in FIG. 16, and the resistance change waveform is shaped to obtain a 3-bit absolute signal.

However, in such an example, as is clear from FIG. 15(A), each magnetization track M. ~The magnetic signals indicated by the arrows in the figure recorded adjacent to M2 have different wavelengths and do not match in polarity, so there is a risk of mutual magnetic interference, as shown in Figure 16. It is thought that there is a possibility that it is difficult to obtain a resistance change waveform like this.

Also, each magnetized track M. - M2, the wavelength of the magnetic signal related to the recording signal is greatly different, so the magnetic field distribution on the surface of the magnetic recording medium of the rotating drum 5 is different, that is, the magnetized track M where the wavelength of the magnetic signal is short. Then, on the surface of the magnetic recording medium, an output as shown in FIG. In this case, the magnetic field distribution becomes pulse-like, and the magnetic field becomes weak in areas far from the surface, and there is a possibility that the output shown in FIG. 16 cannot be obtained.

Therefore, if the magnetic signal is long or short, the optimum output cannot be obtained unless the distance between the surface of the magnetic recording medium and the magnetic sensor is changed, so in this example, the output shown in Figure 16 is is difficult to obtain.

Furthermore, in order to obtain the output as shown in FIG. 16, when recording magnetic signals, if a strong magnet is used at a location where the wavelength of the magnetic signal is long, such as magnetized track M2, then other magnetized tracks This results in a large influence of the magnetic field on the M, .

In addition to the above, if the wavelength of the magnetic signal is long, for example, in the magnetized track M2, the output waveform end will sag, making it difficult to obtain edge precision when shaping the waveform into a square wave. The problem is that a detector is not yet available, which is a serious problem.

[Purpose of the invention]

The present invention provides an apparatus for magnetically detecting a position, which allows signals to be detected with similar sensitivity without causing magnetic interference even on magnetized tracks with different recording lengths of magnetic signals. That is the purpose.

[Summary of the invention]

The configuration of the device for magnetically detecting a position according to the present invention includes a magnetized track having a magnetically recorded magnetic signal of a predetermined length, and a magnetic detection element disposed opposite to this magnetized track. In a system that detects the position of a moving object based on a detection signal obtained by a detection element, there is a magnetic signal section in which a required number of magnetic recording units are consecutive in the moving direction of the moving object, and a non-magnetic field section that does not connect the magnetic recording units. By providing this, a magnetic detection signal is obtained.

Further details are as follows.

The recording length of the magnetic recording signal is such that there is provided a portion where the magnetic poles N and S of the minimum magnetic recording unit are continuously recorded in the moving direction of the track, and a non-magnetic field portion where magnetic recording is not performed.

[Embodiments of the invention]

An embodiment according to the invention, for example for detecting an absolute value, will now be described with reference to each case.

First, FIG. 1 is a schematic configuration diagram of a magnetic rotation sensor which is an embodiment of a device for magnetically detecting a position according to the present invention, and FIG. Diagram (B)
is a plan view of the magnetic sensor, FIG. 3 is a resistance change waveform diagram of the magnetoresistive element, FIG. 4 is a bridge connection diagram of the magnetoresistive element, and FIG. 5 is an output voltage waveform diagram of the bridge. , FIG. 6 is a waveform diagram of the output voltage waveform after waveform shaping.

- In the figure, 4□ is a magnetic sensor in which magnetoresistive elements (hereinafter referred to as MR elements) R81 to R32 related to magnetic detection elements are arranged; 5. is a rotating drum, Mo, with a magnetic recording medium on its surface having the following magnetization tracks:
~M3. are four magnetized tracks on which magnetic signals are recorded on the magnetic recording medium with different recording lengths, respectively.

According to this embodiment, the fourteenth
In the one shown in the figure, the magnetic sensor.

The rotating tram is connected to a magnetic sensor 412 and a rotating drum 5. as shown in FIGS. 1 and 2(A). The present invention relates to an absolute position (absolute) type magnetic rotation sensor having a 4-bit gray code and having a resolution of 1/16 of the magnetic rotation sensor.

That is, the rotating drum 51 is divided into four tracks, and the magnetic poles of the minimum magnetic recording unit of N and S polarities as shown by the arrows in FIG. The recorded magnetic signals are recorded on the four trunks, and the magnetized track M is formed. 1-M3. The wavelength λ related to the minimum magnetic recording unit is equal to the wavelength λ related to the resolution of the magnetic rotation sensor.

Thus, in the magnetization track MO1 related to the least significant bit, two magnetic signals of wavelength λ are continuously recorded, and then,
Those two pieces are not recorded and are left blank, and then two more pieces are recorded in succession, and so on.

In the magnetized track M, 4 related to the second bit of the primary, four magnetic signals of wavelength λ are continuously recorded, and then
It is blank because no individual name is recorded.

Magnetization track M2 related to the next third bit. In this case, eight magnetic signals of wavelength λ are recorded in succession, and then the eight magnetic signals are left blank without being recorded.

Further, the magnetization track M31 related to the most significant bit is the magnetization track M2. Although the recording length is the same as that of the magnetized track M21, its phase is different from that of the magnetized track M21.

That is, the magnetized track M. a9M, &, M2. .

M3. The recording length of each magnetic signal is 2λ.

4λ, 6λ, 8λ, its magnetization track M. ,.

The end of the magnetic signal in M engineering@IM3g is the magnetization track M2. However, they are shifted by λ, 2λ, and 4λ.

The polarities N and S of the adjacent minimum magnetic recording units between the respective magnetized tracks are recorded with the same polarity.

Furthermore, the magnetic poles N and S of the adjacent minimum magnetic recording units of each magnetization track are arranged to have the same polarity.

Further, in order to make a part without a minimum magnetic recording unit in the same magnetized track a non-magnetic field part, the poles of the ends of adjacent magnetic signals separated by this region are made to be the same polarity.

In short, the above-mentioned apparatus is provided with a magnetic signal section in which a required number of magnetic recording units are consecutive in the moving direction of the moving body, and a non-magnetic field section in which there are no magnetic recording units.

Next, in the magnetic sensor 41, an MR element is arranged close to each magnetization track, as shown in FIGS. 2(A) and 2(B).
As shown in the magnetized trunk M. , the MR element Rol, R,2 relating to the least significant bit is arranged opposite to the magnetization track M1 . ~M3. pertain to the second, third and most significant bits, respectively. MR element R engineering 4.
R1□, R2□, R2□ and R31, R3□ are arranged.

In addition, MR elements R81 and R82, the same elements R11 and R12
, the same elements R2□ and R2□, the same elements R3□ and R3□,
The respective MR elements are arranged to be shifted from each other by λ/2, which is half the wavelength λ, and the MR elements are arranged on the same line as shown in the figure.

Therefore, in this embodiment, when a magnetic field perpendicular to the longitudinal direction of each MR element Ra1 to R3□ is applied, the resistance value utilizes the undercolor characteristic.

That is, with the arrangement configuration as shown in FIGS. 2(A) and (B),
Rotating drum5. When you move in the direction of the arrow shown in the figure, each MR
The resistance of each of the elements R81 to R3□ changes as shown in FIG.

In addition, as shown in FIG. 3, in both cases, the wavelength changes in the minimum magnetic recording unit according to wavelength &, so the wavelength edge becomes sharp.

Furthermore, since the magnetic fields from each magnetization track to the magnetic sensor are approximately equal, even if the distance between the magnetic recording medium and the magnetic sensor is the same for each magnetization track, approximately the same resistance change can be obtained. .

In such a magnetic rotation sensor, each of these MR elements R6□ to R32 and the resistor R1, for example, the rotating drum 5. which is arranged on the magnetic sensor 41 or separately attached and arranged. Resistance R related to other MR elements or resistors that are not affected by the magnetic field of
If a resistor bridge is constructed for each magnetized track as shown in FIG. 4, and each bridge is used by applying a voltage from the power supply V, the absolute position can be determined in the following manner. It is something that can be detected.

That is, the output terminal a is a detection terminal related to the least significant bit of each magnetized trunk. The output voltage between lbo and e. Closing, similarly, a process related to the second bit.

The output voltage between b1 is el, and the third bit is a21b2.
If the output voltage between a31 and b3 related to the most significant bit is 82 r 83 , then the output voltage e of each of these magnetized tracks is 82 r 83 . -e3, as shown in FIG. 5, even if the output signal lengths are different, the waveform ends are sharp in the same way.

FIG. 5 is a waveform diagram of voltage e01 that matches the sum of voltage changes due to resistance changes shown in FIG. That is, the magnitude of the voltage is e. □There is.

This output voltage e. -e3 is waveform-shaped by an amplifier or voltage comparator, etc., resulting in E shown in FIG.

-E, the waveform is as follows.

This E. -E3 is the output of a 4-bit gray code, in which a signal change of each bit appears every λ, and the absolute position divided into 16 equal parts can be detected.

As explained above, in this embodiment, FIG.
A magnetic detection signal can be obtained by providing a magnetic signal section for recording magnetic signals and a non-magnetic field section as explained in A).

Since magnetic signals are recorded in this way, the magnetic poles that face each other across the non-magnetic field area where there is no minimum magnetic recording signal in the moving direction of the magnetized track are the same polarity as the north poles or the south poles. As a result, they repel each other and create a completely non-magnetic field area, which also improves the precision of the magnetic signal.

In addition, when looking between each magnetized track, the N poles or S poles face each other and repel each other, so there is no magnetic interference.Also, since recording can be performed at the same minimum magnetic recording unit wavelength, each magnetized track The magnetic field distribution is uniform, and even if the distance between the magnetic recording medium and the magnetic sensor is the same for each magnetized track, the output will be approximately the same for each magnetized track, and a stable output will be obtained.

Furthermore, since the edges of the output waveform change sharply, accuracy is improved and high resolution can be achieved.In the above embodiment, the magnetic pole pitch of the minimum magnetic recording unit was made equal to the resolution of the magnetic rotation sensor. Below that resolution or
If it is reduced to one integer fraction, the output waveform end can be made sharper.

In addition to the above, in the above embodiment, an example of 4 bits was shown, but even if the number of bits increases, such as 5 bits with a resolution of 1/32 or 8 bits with a resolution of 1/256,
A similar effect can be obtained, and the Gray code is often used as a magnetic rotation sensor because only one bit changes when the value changes.
The same effect can be obtained even with pinary chords in which two or more chords change together.

Therefore, in the above, each MR element is shifted by λ/2, which is half the wavelength λ, but this is n
When is an integer, (n 2 )λ can be selected, and the same effect can be achieved.

Next, other embodiments will be described with reference to FIGS. 7 to 1J.

Therefore, this embodiment relates to a 4-bit gray code in which each pin 1-2 magnetized I-rack is used to increase the output voltage.

Here, FIGS. 7A and 7B are a developed view of a rotating drum of a magnetic rotation sensor according to another embodiment of the present invention and a plan view of the magnetic sensor, and FIG. 8 is a bridge of the MR element. The connection diagram, FIG. 9 is a resistance change waveform diagram of the MR element, FIG. 10 is an output voltage waveform diagram of the bridge, and FIG. 11 is a waveform diagram of the output voltage waveform after waveform shaping.

In the figure, 41 is an MR element R8 related to a magnetic detection element.
In the magnetic sensor 5, in which magnetic signals 1 to R34 are arranged, magnetic signals are recorded with different recording lengths in each track, and magnetized tracks M each have a set of two magnetized tracks related to the same bit. k~M3. It is a rotating drum with a

According to this embodiment, as in the previous embodiment, in the magnetic rotation sensor shown in FIG. 14, the magnetic sensor and the rotating drum are connected to the magnetic sensor 412 and rotating tram 51 as shown in FIG. The present invention relates to an absolute position (absolute) type magnetic rotation sensor having a 4-bit gray code as described above.

That is, rotating drum 5. is divided into eight tracks, N as shown by the arrows in FIG.

The magnetic poles of the minimum magnetic recording unit of S polarity and the same wavelength λ are recorded in eight tracks, and the magnetized track (a)
～(H) and magnetized tracks (A) and (B).

(c), (d), (e), (e), N-), (ch)
Each of the two magnetizations 1 to Rack corresponds to a 1-bit magnetization track. Bottom, 2nd place. Magnetization track M of the third and most significant bit. ,~M3. The wavelength λ is the resolution (1/16) of the magnetic rotation sensor.
This is the same as that related to .

Therefore, the pattern of the magnetized trunks (A) in the magnetized tracks M related to the lowest pins 1 to 1 is the same as the magnetized track M in the previous embodiment. Same recording pattern as 4, except that the magnetized track (b) is the same as the magnetized track (a).
The information is not recorded in the portion corresponding to the recorded portion, and is recorded in the portion corresponding to the unrecorded portion.

Similarly, the second. Magnetization track M1□M zb+ M3. related to the third and most significant bit. The magnetization track at (
C), (E), and (G) are the magnetization tracks M0. in the previous embodiment. ．． M, □2M3. The recording pattern is the same as that of the magnetized track (d), and the magnetized track (d) and
(F) and (H) are recorded in the same corresponding recording mode as above, and each set of magnetized trunks M□59M2 related to the same bit.
□M3.

And, as in the example of the rabbit, the magnetic pole N of wavelength λ at the adjacent location in each magnetization track.

S means to record the same.

Next, magnetic sensor 4. In, the lowest, second, third
．． Magnetization track M related to the most significant bit. , ~M3,
, the lowest, the second, and so on. MR elements R81 to R, 4°R□1 to R1, related to the third and most significant bit;
, R2□ to R24, and R3□ to R34 are arranged as shown in the figure, and the MR element R6□1Rfl: ItR construction 1. R, R2, R23, R31, and R13 are arranged in a straight line, and MR elements R02y Ro4. R1□, R14,R,□,
R24, R3□.

With this arrangement, the rotating drums 5. When moving in the direction of the arrow shown in the figure, the MR elements R8, to R1 each become
The resistance changes as shown in FIG.

If each of these MR elements is used by configuring a bridge for each bit and applying voltage from the power supply ■, as shown in FIG. . And. and the voltage between eo and the other second . Third
．． The voltage e□ between the output terminals a1 and bl of the least significant bit, the voltage e2 between the output terminals a2 and b2 + the same terminal a3
The voltage e3 between b3 and b3 becomes as shown in FIG.
Double the voltage can be obtained.

Furthermore, in the present embodiment, the output waveform edge of each bit also changes sharply.

When the above output voltages e, ``'-e'' are waveform-shaped through an amplifier or a voltage comparator, outputs E0 to E3 as shown in FIG. 11 are obtained, and a 4-bit gray code is obtained.

As described above, the device according to this embodiment can be expected to have the same effect as the Sagi embodiment, and can also increase the amplitude of the output voltage and improve accuracy. In addition, various selections can be made in the same manner as in the Sagi embodiment, such as the selection of the wavelength related to the minimum magnetic recording unit and the increase in the number of bits.

In each of the embodiments described above, a drum-shaped rotating drum 5. , '5. These rotating drums may be in the form of a rotating disc or a rotating disk.

That is, FIGS. 12 and 13 show an embodiment in which a rotary disk is used instead of a rotary drum.

Here, FIG. 12 is a block diagram of a magnetic rotation sensor according to another embodiment of the present invention, and FIG. 13 is a diagram of the relationship between the rotating disk and the magnetic sensor.

In the figure, the same symbols as in Figure 1 indicate equivalent parts.
3-1 is a mounting base, 4-1 is an MR element R8-1, R-1. The magnetic sensor 5-1 in which R2-1°R3-1 is arranged has four magnetized tracks M o , in which magnetic signals are recorded with different recording lengths on each track.
It is a rotating disk with M 3°.

That is, the rotating disk 5-1 concentrically forms a magnetization track Moe related to the lowest bit from the outer periphery, then
Second. Magnetization track M1゜g MZ related to third pin 1-
. , furthermore, a magnetization trunk M3° related to the most significant bit is arranged, and two MR elements Ro-1, R, -1, R2-, respectively, of the magnetic sensor 4-1 are placed close to these trunks.
1, R3-1 are arranged facing each other in a straight line.

In this case, the minimum magnetic recording unit is the angle θ.

The same effects as those of the Sagi embodiments can be expected in this embodiment as well.

According to each of the embodiments described above, (1) magnetic signals with different recording lengths can be recorded without magnetic interference;
) By making the part where the minimum magnetic recording unit is not recorded a completely magnetic field-free part, highly accurate signal recording is possible. (3) Recorded signals can be detected with the same sensitivity, so the magnetic recording medium and magnetic sensor can (4) The edges of the output signal can be made sharp regardless of whether the recording length is long or short.
With these, it is possible to provide high precision and high resolution.

Up to now, the explanation has been given using an example of a rotating body as a moving body, but the position detection of an object that moves in a straight line can be similarly performed and the same effect can be obtained. Furthermore, although we have shown an example in which multiple tracks are used to record magnetic signals and repeated magnetic signals are recorded on each track, it is possible to use only one track.
The length of the magnetic signal is changed and recorded, and depending on the length of the signal, it can be used to detect the position, and a similar effect can be obtained.

〔Effect of the invention〕

According to the present invention, there is provided an apparatus for magnetically detecting a position, which allows signals to be detected with similar sensitivity without causing magnetic interference even on magnetized tracks having different recording lengths of magnetic signals. It is something that can be done.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of a magnetic rotation sensor, which is two embodiments of a device for magnetically detecting a position according to the present invention, and Fig. 2 (A) and (B') show the development of the rotating drum. Figure 3 is a resistance change waveform diagram of the magnetoresistive element, Figure 4 is a bridge connection diagram of the magnetoresistive element, and Figure 5 is the output voltage waveform of the bridge. 6 is a waveform diagram of the output voltage waveform after waveform shaping,
Figure 7(A). (B) is a developed view of a rotating drum of a magnetic rotation sensor according to another embodiment of the present invention and a plan view of the magnetic sensor, and FIG.
The bridge connection diagram of the magnetoresistive element, Fig. 9 is the resistance change waveform diagram of the magnetoresistive element, Fig. 10 is the output voltage waveform diagram of the bridge, and Fig. 11 is the waveform of the output voltage waveform. FIG. 12 is a waveform diagram after shaping, and FIG. 13 is a configuration diagram of a magnetic rotation sensor according to another embodiment of the present invention.
FIG. 14 is a diagram showing the relationship between the rotating disk and the magnetic sensor, and FIG. 14 is a configuration diagram of a known angle detector, FIG. 15, FIG. 3, FIG. 41, FIG. 5, and FIG. z [3 Figure 9 (μ Figure 10 /1 Figure !2 Country? Figure 73

Claims (1)

[Claims] 1. Consisting of a magnetized track having a magnetically recorded magnetic signal of a predetermined length and a magnetic detection element disposed opposite to this magnetized track, and detection obtained by the magnetic detection element. In a device in which the position of a moving object is detected based on a signal, by providing a magnetic signal section in which a required number of magnetic recording units are consecutive in the moving direction of the moving object, and a non-magnetic field section without magnetic recording units, A device for magnetically detecting a position, characterized in that it is configured to obtain a magnetic detection signal. 2. An apparatus for magnetically detecting a position according to claim 1, wherein the non-magnetic field portion has a pitch λ or more of the magnetic recording unit of the magnetic signal portion.