JPH061201B2 - Position detection sensor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position detection sensor, and more particularly, it utilizes magnetism to detect the position of a moving body such as a rotating body or a displacement body, and yet obtains a sine wave output. The present invention relates to a position detection sensor suitable for.

[Background of the Invention]

The position detecting sensor previously filed by the applicant of the present invention (Japanese Patent Application No. 59-166496) was provided with a compensating sensor for correcting a change in sensor output due to a change in spacing. However, no consideration was given to the magnetic recording of the compensation sensor.

Therefore, the output of the compensation sensor does not change remarkably with respect to the spacing change due to the eccentricity of the rotating body, and sufficient correction cannot be obtained as a position detection sensor that obtains a sine wave output.

[Object of the Invention]

The present invention has been made in view of the above, and an object thereof is to change a spacing, which is a distance between a magnetic recording medium on which a magnetic signal is recorded and a magnetic sensor arranged to face the magnetic recording medium, An object of the present invention is to provide a position detection sensor that can take out a stable sine wave analog signal as an output of a magnetic sensor.

[Outline of Invention]

The present invention relates to a magnetic recording medium having a signal track in which a magnetic signal is recorded on a moving body or a surface which is not fixedly mounted, and a magnetoresistive element provided in a fixed portion or a moving portion arranged at a position facing the magnetic recording medium. And a magnetic sensor for detecting a moving position of the moving body or a moving portion as a resistance change of the magnetoresistive element, the first signal track recording a magnetic signal on the magnetic recording medium. And a second signal track having a plurality of channels and recording a magnetic signal in a direction different from the magnetic signal recorded in the first signal track, and the magnetic sensor opposes the first signal track. A first magnetoresistive element and a second magnetoresistive element facing a track other than both ends of the second signal track. A change in the distance between the recording medium and the magnetic sensor is detected as a change in resistance of the second magnetoresistive element, and the detection signal detected by the first magnetoresistive element is detected by the detection signal of the second magnetoresistive element. It is characterized in that the signal is corrected.

Example of Invention

The present invention will be described in detail below with reference to the embodiments shown in FIGS. 1, 2, 6, and 7 and FIGS.

FIG. 1 is a block diagram showing an embodiment of the position detection sensor of the present invention, and FIG. 2 is an enlarged development view showing a part of FIG. In FIG. 1, reference numeral 1 is an axis of a rotating moving body, to which a magnetic drum 2 on which a magnetic recording medium is arranged is fixed. The magnetic recording medium is composed of first and second signal tracks 21 and 22, and the first signal track 21
Is used for a position detection sensor that obtains a sine wave output,
N.S. magnetic signals are recorded at intervals of recording pitch .lambda. In the circumferential direction. The second signal track 22 is composed of three channels M ₀ , M ₁ and M ₂ and is a signal in which a change due to a change in spacing of the analog signal obtained by the first signal track 21 is corrected. It is provided for the purpose of recording the magnetic field, and magnetic signals of N · S are recorded on the entire circumference in the axial direction. That is, the first channel M ₀ of the second signal track 22 is N · S by the recording head in the axial direction.
The (S.N) magnetic signal is recorded, and the second channel M ₁ is displaced in the axial direction by the amount of the head gear of the recording head, and the magnetic signal and the recording direction of the first channel M ₀ are recorded. The magnetic signals of S · N (N · S) are recorded so as to be reversed. Also, the third channel M ₂
Similarly, the magnetic signal of N · S (S · N) is recorded so that the magnetic signal of the second channel M ₁ is reversed by shifting the position in the axial direction by the amount of the head gear of the recording head. .

A magnetic sensor 3 is arranged so as to face the magnetic drum 2 on which the magnetic recording medium is arranged, with a spacing 1 _S interposed therebetween. This magnetic sensor 3 is composed of two parts. That is, one is a first magnetoresistive element 31 arranged in a portion facing the first signal track 21 of the magnetic drum 2 and is long in the axial direction, and the other is a first magnetoresistive element 31 as shown in FIG. The second magnetoresistive element 32 is long in the circumferential direction and is arranged so as to face the channels M ₁ other than the outermost channels M ₀ and M _{2 in the} second signal track 22. The magnetoresistive elements 31 and 32 change their electric resistances when a magnetic field is applied in a direction perpendicular to their longitudinal directions. Therefore, in such a configuration, when the magnetic drum 2 rotates, a magnetic field corresponding to the magnetic signal recorded in the first signal track 21 of the magnetic drum 2 is applied to the magnetoresistive element 31. Therefore, since the resistance of the magnetoresistive element 31 changes, if a current is applied to the magnetoresistive element 31,
A voltage change corresponding to the rotation of the magnetic drum 2 is obtained.

On the other hand, the magnitude of the magnetic field with respect to the magnetoresistive element 31 also changes depending on the spacing l _S. That is, as the spacing l _S becomes wider, the magnetic field becomes weaker and the spacing l
_{When S} is sandwiched, the magnetic field becomes stronger.

The magnetic resistance element 32 facing the second signal track 22 of the magnetic drum 2 does not change the magnetic field from the magnetic drum 2 if the spacing l _S is constant even when the magnetic drum 2 rotates. , Resistance change does not occur. However, when the magnetic drum 2 rotates due to the difference in processing accuracy and the eccentricity when the magnetic drum 2 is attached to the shaft 1, the spacing l _S varies. In this case, as shown in FIG. 3 (b), the output e _C of the magnetoresistive element 32 is
It changes in response to changes in spacing l _S. Similarly,
Also in the output e _R of the magnetoresistive element 31, as shown in FIG. 3 (a), a change corresponding to the change in the spacing l _S appears superposed on the change due to the magnetic signal. For example, when the spacing l _S is wide, the outputs e _C and e _R of the magnetoresistive elements 32 and 31 are lowered as shown at point (b) in FIG.
When the spacing l _S is narrow, if the changes in e _C and e _R change with a similar slope with respect to the spacing l _S as shown in point (a) of FIG. 3, correction is easy and circuit processing is also performed. It will be easy.

The relationship between the outputs e _C and e _{R of the} magnetoresistive elements 32 and 31 and the spacing l _S is measured as shown in FIG.
In FIG. 4, a curve is e _C , b in the case of the present invention.
The curve is a characteristic curve of e _{R in} the case of the present invention, and the characteristic curve of e _C in the case of the previous application shown for reference.

In the output e _R, becomes below a certain value the spacing l _S, the magnetic sensor 3 is saturated, the output waveform is distorted from the sine wave, the spacing l _S at this time
It is good to use above. On the other hand, for the output e _C ,
According to e _C indicated by c curve before application, because the tracks for compensation was one and, in the case of a magnetic recording by the recording head, since having a width that the tip portion of the recording head, apparently recorded It is recorded in a wider width than the head gear tape. Therefore, the magnetic flux distributions of the signal tracks 21 and 22 are different, and the same inclination cannot be obtained. On the other hand, according to the embodiment of the present invention, as can be seen from FIG. 4, the output e _{C represented} by the curve a and the output e _{R represented} by the curve b are in substantially the same relationship due to the effect of the plurality of channels. Become. Here, FIG. 5 is a detailed development view for explaining the relationship between the magnetic drum 2 and the magnetic sensor 3 of FIG. 1 in detail. The first signal track 21 of the magnetic drum. 2 are recorded magnetic signals N · S of the recording pitch λ is, the magnetoresistive element 31 of the magnetic sensor 3 which faces this, the magnetoresistance element 31 _{1-31 4} Λ / 2 for the recording pitch λ
They are separated from each other. A second signal track 22 having a plurality of channels M _{0 to} M ₂ of the magnetic drum 2 is also provided.
, The magnetic signals of N and S are respectively recorded in the direction perpendicular to the magnetic signal of the first signal track 21, and the magnetoresistive element 32 of the magnetic sensor 3 facing this is the magnetoresistive elements 31 ₁ , 32. ₂ and ₂ are arranged in directions orthogonal to each other. Therefore, the magnetic signal of the second signal track 22 is detected only by the magnetoresistive element 32 ₁ .

FIG. 6 is an electrical connection diagram showing an embodiment of the magnetic sensor 3 of FIG. In FIG. 6, the magnetoresistive elements 32 ₁ and 32 ₂ are connected in series between the constant voltage V ₁ and the ground. An output is obtained from the intermediate point a of the magnetoresistive elements 32 ₁ and 32 ₂ and is added to the inverted input of the amplifier 40. ing. The magnetic field from the second signal track 22 is effective for the magnetoresistive element 32 ₁ and
₂ does not work effectively. A bias voltage V ₀ is applied to the non-inverting input of the amplifier 40 for amplification. This amplifier 4
Between the output V _{3 of} 0 and the negative point of the constant voltage V ₂ ,
Magnetoresistive elements 31 ₁ and 31 circuit and a series circuit connected in parallel with the series circuit and the magnetoresistive element 31 ₃ and 31 ₄ and ₂ are then connected, constitute them in Buritsuji circuit, Buritsuji output Is amplified by the amplifier 41, and the output terminal 42
A more output signal is obtained. Therefore, when the spacing l _S becomes wider due to the eccentricity of the magnetic drum 2 or the like, the magnetic field of the magnetoresistive element 32 ₁ becomes weaker and the resistance value increases, so that the voltage at the intermediate terminal a decreases and the amplifier 4
The output voltage V _{3 of} 0 rises. On the other hand, the magnetoresistive element 31
_{1-31 4} to a first signal magnetic field applied from track 21 is also a weaker if wider spacing l _S connexion, voltage also decreases obtained from the output terminal of Buritsuji circuit consisting of the magnetoresistive element 31 _{1-31 4} However, since the output voltage V ₃ of the amplifier 40 increases as described above, the voltage at the bridge output terminal is prevented from decreasing. When the spacing l _S is narrowed, the output voltage V ₃ of the amplifier 40 is prevented from being lowered and the voltage at the bridge output terminal is prevented from rising, which is the reverse of the case where the spacing l _S is wide, and it is always constant. It operates so as to obtain the sine wave of the output.

In the Figure 6, there is a structure to be added to one end of Buritsuji circuit comprising an output voltage _{V 3} of the amplifier 40 from the magneto-resistive element ₃₁ 1-31 _4, amplification by connexion amplifier 41 the output voltage _{V 3} of the amplifier 40 The same effect can be obtained even if the rate is controlled.

FIG. 7 is a block diagram corresponding to FIG. 1 showing another embodiment of the present invention. FIG. 7 shows a position detection sensor for detecting a position when the moving body makes a linear motion or the like. Two signal tracks 21 'and 22' are provided on the surface of the moving body 2 '.
A magnetic recording medium having a first signal track 2
In 1 ', magnetic signals of N.S are recorded in the moving direction of the moving body 2'by the recording pitch λ, and in the second signal track 22' composed of a plurality of channels M _{0 to} M ₂ , the moving direction is recorded. N so that the polarities of each channel are the same in the direction perpendicular to
・ S magnetic signal is recorded. And this in the opposite way magnetic sensor 3 'first secure the signal track 21' to the opposite portions of the magnetic resistance element 31 ₁ to 31 ₄ are arranged at each lambda / 2 spacing, multiple channels M ₀ ~ M ₂
The magnetoresistive elements 32 ₁ and 32 ₂ are arranged in a direction orthogonal to each other in a portion facing the second signal track 22 ′ constituted by. Therefore, when the moving body 2'moves, it becomes the same as when the magnetic drum 2 of FIG. 5 described above rotates, and the spacing l _S is changed by the circuit of FIG. 6 connected thereto. On the other hand, a constant and stable sine wave output can be maintained.

Although the magnetic sensor 3'is fixed in FIG. 7, the magnetic sensor 3'may be moved to fix the magnetic recording medium on which a magnetic signal is recorded, and the same effect is obtained. be able to.

〔The invention's effect〕

As described above, according to the present invention, since the second signal track has a plurality of channels, it is possible to have the same magnetic flux distribution as the magnetic flux distribution obtained by the first signal track, and to avoid a spacing change. Since the change in the output signal of the magnetic sensor obtained by the first and second signal tracks can be made the same, correction due to the change in spacing becomes easy, and the amplification factor of the amplifier can be made low. ,
There is an effect that it becomes strong against noise and a stable sine wave output is obtained.

[Brief description of drawings]

1 is a block diagram showing an embodiment of the position detecting sensor of the present invention, FIG. 2 is an enlarged development view showing a part of FIG. 1 in an expanded manner, and FIG. 3 is a magnetoresistive element in FIG. Output waveform explanatory diagram of
FIG. 4 is a relational diagram between the spacing and the output of the magnetoresistive element, FIG. 5 is a detailed enlarged development view for explaining the operation of FIG. 1, and FIG. 6 is an electrical diagram of the position detection sensor of the present invention. FIG. 7 is a circuit diagram showing one embodiment of connection, and FIG. 7 is a configuration diagram corresponding to FIG. 1 showing another embodiment of the present invention. 1 ... Shaft of moving body, 2 ... Magnetic drum, 2 '... Moving body, 3,
3 '... magnetic sensor, 21, 21' ... first signal track, 22, 22 '... second signal track, 31, 31 ₁
˜31 ₄ , 32, 32 ₁ , 32 ₂ ... Magnetoresistive element, 4
0,41 ... Amplifier.

Claims (5)

[Claims] 1. A magnetic recording medium having a signal track on which a magnetic signal is recorded on a surface attached to a moving body or a fixed body, and a magnetic resistance provided in a fixed portion or a moving portion arranged at a position facing the magnetic recording medium. A magnetic sensor formed of an element, wherein the moving position of the moving body or the moving portion is taken out as a resistance change of the magnetoresistive element, wherein a magnetic signal recorded on the magnetic recording medium is recorded. A signal track and a second signal track, which is composed of a plurality of channels and has a magnetic signal recorded in a direction different from that of the magnetic signal recorded in the first signal track, are provided, and the magnetic sensor is provided with the first signal. A first magnetoresistive element facing the track and a second magnetoresistive element facing the track other than both ends of the second signal track, A change in the distance between the magnetic recording medium and the magnetic sensor is detected as a change in resistance of the second magnetoresistive element, and is detected by the first magnetoresistive element based on a detection signal of the second magnetoresistive element. A position detection sensor having a configuration for correcting the detected signal. 2. A second signal track composed of a plurality of channels, wherein a magnetic signal recorded in the first signal track and a magnetic signal in a direction perpendicular to the magnetic signal recorded in the first signal track are recorded. Position detection sensor. 3. The second magnetoresistive element is arranged so as to detect a magnetic signal of a channel other than the outermost portion of the plurality of channels of the second signal track, and the first magnetic resistance element is provided. The position detection sensor according to claim 1 or 2, wherein the position detection sensor is formed in the same chip as the resistance element. 4. The magnetic signal of the odd numbered channel of the second signal track is recorded in a direction perpendicular to the moving direction of the magnetic recording medium, and the magnetic signal of the even numbered channel is the magnetic signal of the odd numbered channel. The position detection sensor according to claim 1, 2 or 3, wherein recording is performed so that the recording directions are reversed. 5. A magnetic signal is recorded by a recording head in the second signal track, and a magnetic signal interval of each channel is set to be substantially equal to a head gear gap of the recording head. The position detection sensor according to item 2 or item 3 or item 4.