JP2001227904A - Magnetic scale unit and device using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic scale unit capable of providing high resolution by doubling the number of pulses of electric signals output from a conversion means, without narrowing magnetization pitches, and devices using it. SOLUTION: The magnetic scale unit 10 has a line of magnetic poles 56 comprising a plurality of magnetic poles 54 aligned in equally spaced relationship on a base 52. The magnetic poles 54 are of the same polarity and the spacing Ls between the magnetic poles 54 is greater than the width Lm of each magnetic pole 54 in their alignment direction but smaller than twice the width Lm. Using the magnetic scale unit 10, a signal generator with increased resolution, a displacement detecting device with increased displacement detecting accuracy, and a motor control device with increased stability for the rpm of a motor can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting a displacement or a position of a head such as a pickup or a magnetic head used for recording / reproduction of an optical disk device or a magnetic disk device, and for detecting an optical disk or a magnetic disk. The present invention relates to a magnetic scale unit used when controlling the number of rotations of a motor to be rotated.

[0002]

2. Description of the Related Art A magnetic scale unit is composed of a substrate having an outer shape formed in a disk shape or a long plate shape, and a plurality of magnetic poles formed on the substrate at equal pitches so as to extend in a circumferential direction or a longitudinal direction. And a pole row arranged side by side. As the magnetic pole array, there is a magnetic pole array in which a plurality of magnets are arranged on a substrate, or a magnetic pole array formed by magnetizing a magnetic material substrate.

[0003] Such a magnetic scale unit will be described in detail with reference to FIG. In the magnetic scale unit 50, the base 5 whose outer shape is formed in a disk shape or a long plate shape is used.
A plurality of magnets 53 are arranged at equal pitches (λ) along the circumferential direction or the longitudinal direction on the side of the end of 2. The magnetic poles 54 (N-pole and S-pole) formed on the end surfaces of the magnets 53 on the end side of the base 52 constitute a magnetic pole row 56 of the magnetic scale unit 50.

A conversion means 58 such as an MR sensor or a magnetic sensor using a Hall element is provided opposite to the magnetic pole row 56 so that a change in the magnetic field line b between the magnetic poles 54 is detected by the conversion means 58. Detects the amount of displacement and the current position of a head such as a pickup or a magnetic head used for recording / reproduction of an optical disk device or a magnetic disk device, and controls the rotation speed of a spindle motor for rotating an optical disk or a magnetic disk. Used for

More specifically, for example, when detecting the displacement or position of a head, a conversion means 58 is attached to a carriage for transferring a head used for recording / reproduction such as an optical disk drive or a magnetic disk drive, and the conversion means 58 is provided. The magnetic scale unit 50 is arranged along the moving direction of the means 58 so that the magnetic pole row 56 of the magnetic scale unit 50 and the conversion means 58 face each other. As a result, when the head moves, the conversion means 58 and the magnetic scale unit 50 are relatively displaced. Therefore, the conversion means 58 outputs a change in the magnetic field of the magnetic pole row 56 (the loop waveform of the magnetic field line b between the magnetic poles 54). An electric signal a that changes correspondingly is output at a frequency proportional to the relative speed between the head and the magnetic scale unit 50. Therefore, by counting the number of pulses included in the electric signal a, the conversion means 58 and the magnetic scale unit 5 are counted.
0 relative displacement, ie, the head and the magnetic scale unit 5
A relative displacement amount of 0 can be detected, and the relative displacement speed between the head and the magnetic scale unit 50 can be detected by detecting the number of pulses included in the electric signal a detected per unit time.

A conventional magnetic scale unit 50 is disclosed in, for example, Japanese Patent Application Laid-Open No. 2-54881, and as shown in FIG.
The configuration is such that the poles and the S poles are arranged alternately.
As described above, in the case of the magnetic scale unit 50 in which the N poles and the S poles are alternately arranged, for example, as shown in FIG. Becomes a loop waveform input to the adjacent magnetic pole 54.

Therefore, the electric signal a output from the converting means 58 (for example, a magnetic sensor using a Hall element for detecting the magnetic flux density in the direction of the arrow) has an amplitude (for example, Is an AC signal having a peak in voltage amplitude and having one cycle (the cycle is 2λ) between adjacent N poles. Therefore, when the conversion means 58 moves from the N pole to the next N pole, the electric signal a output from the conversion means 58 has a voltage peak (both positive and negative peaks).
Are included. In other words, only one peak is included in the electric signal a during the time when the displacement amount moves from the half N pole to the adjacent south pole, that is, between the magnetic poles 54. The electric signal a is rectified, so that each peak becomes one pulse.

[0008]

By the way, in recent years, as optical disks and magnetic disks have become smaller and larger in capacity, track pitches have become narrower, and heads such as optical pickups and magnetic heads have been positioned with even higher precision. Is being required. Similarly, the rotation speed of optical disks and magnetic disks has been increasing, and the stability of the rotation speed itself has been required to be higher. High accuracy is required. For this reason, the magnetic scale unit has been required to have higher resolution.

[0012] In the case of the conventional magnetic scale unit 50 shown in FIG. 12, the electric power output from the conversion means 58 is not circulated until the conversion means 58 such as a magnetic sensor moves between the adjacent magnetic poles 54 as described above. Since the signal a includes one peak (which is also a pulse),
In order to increase the resolution, it is necessary to further narrow the pitch λ of each magnetic pole 54. For example, in order to double the resolution, the pitch of each magnetic pole 54 needs to be 0.5λ.

However, even now, the magnetic pole pitch has been narrowed to an appropriate interval in order to increase the resolution of the magnetic scale unit, and in order to further narrow the magnetic pole pitch, the use of a magnetizing head having a narrower gap has been considered. It is necessary to form the magnetic poles while positioning the magnetizing head with higher accuracy, and a high level of technology is required, so that there is a problem that the manufacturing cost of the magnetic scale unit increases. In addition, since the N pole and the S pole must be alternately magnetized, current control to the magnetizing head becomes complicated, and there is a problem that the manufacture of the magnetic scale unit is troublesome and troublesome.

The biggest problem associated with reducing the magnetic pole pitch is that the required signal magnetic field decreases due to the decrease in the volume to be magnetized, so that the level of the electric signal output from the conversion means is higher than a processable level. In this case, the distance between the pole face and the conversion means must be further reduced. Because, if the distance between the magnetic pole surface and the conversion means is to be further reduced, it is necessary to assemble with higher precision than before, and even if it is assembled with high precision, it will be susceptible to the influence of floating dust in the device. For,
This is because there arises a problem that a stable level electric signal cannot be obtained from the conversion means.

The present invention has been made in view of such a conventional situation,
An object of the present invention is to provide a magnetic scale unit that can further increase the number of pulses included in an electric signal output from a conversion unit and obtain high resolution without making the magnetization pitch narrower than before. It is another object of the present invention to provide a signal generator with increased resolution, a displacement detection device with improved displacement detection accuracy, and a motor control device with increased stability of the number of revolutions of a motor, using this magnetic scale unit. I do.

[0013]

Means for Solving the Problems To achieve the above object, a magnetic scale unit provided by the present invention is a magnetic scale unit having a magnetic pole array in which a plurality of magnetic poles are arranged on a substrate at regular intervals at intervals. The magnetic poles have the same polarity, and the interval between the magnetic poles is larger than the width in the arrangement direction of the magnetic poles and smaller than twice the width in the arrangement direction of the magnetic poles.

In the magnetic scale unit according to the present invention, the base is made of a non-magnetic material, and the magnetic poles are constituted by magnetic poles of the same polarity of permanent magnets disposed in the base. The base is a magnetic material, and the magnetic poles are constituted by magnetic poles of the same polarity formed by magnetizing the base. The base of the magnetic scale unit may be a disk or a long plate. However, for control of various disk devices, the base is preferably a disk, and the same circle around the rotation axis of the base is preferable. A plurality of magnetic poles are arranged on the circumference.

Further, the present invention provides various application devices using the above-mentioned magnetic scale unit, and one of them is a signal generator which includes the above-mentioned magnetic scale unit and a magnetic pole array of the magnetic scale unit. And a conversion means for converting a change in a magnetic field due to a relative displacement with the magnetic scale unit into an electric signal. Further, the displacement detection device includes the signal generator described above, and an arithmetic unit that detects a relative displacement amount and / or a relative displacement speed between the magnetic scale unit and the conversion unit based on an electric signal from the signal generator. Features.

Further, in the motor control device provided by the present invention, in the above-mentioned magnetic scale unit, the rotating shaft of the disk-shaped base is directly or indirectly attached to the output shaft of the motor, and the rotation of the output shaft is controlled. A magnetic scale unit that rotates the base, a driving unit that drives the motor, and a magnetic field that is provided to face the magnetic pole array of the magnetic scale unit and that is caused by a relative change between the magnetic scale unit and the output shaft that rotates. Converting means for converting the change of the output shaft into an electric signal, calculating means for detecting the rotation speed of the output shaft based on the electric signal from the converting means, and the output based on the rotation speed of the output shaft detected by the calculating means. Control means for controlling the driving means of the motor so that the number of rotations of the shaft becomes a desired number of rotations.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, first,
As shown in FIG. 1, the adjacent magnetic poles 54 constituting the magnetic pole row 56 of the magnetic scale unit 10 have the same polarity (N pole in the figure). A place arises. For this reason, when the change of the magnetic field of the magnetic scale unit 10 is detected by the conversion means 58, the amplitude of the electric signal a output from the conversion means 58 becomes
A position where the conversion means 58 faces each magnetic pole 54 (each magnetic pole 54
Not only at the front of the magnetic pole 54) but also at the intermediate portion between the magnetic poles 54. Therefore, the electric signal a output when the conversion means 58 moves between the adjacent magnetic poles 54 is 2
One peak is included, and the resolution of the magnetic scale unit 10 is doubled even with the same magnetization pitch as compared with the related art.

However, as shown in FIG.
In the case where the width Lm in the arrangement direction and the interval Ls between the magnetic poles 54 are equal to each other, the electric signal a output from the conversion unit 58 is compared with the electric signal at the position facing the magnetic pole 54. Since the electric signal at the intermediate position between the magnetic poles 54 is relatively weaker, the detected signal becomes asymmetric between positive and negative and the duty ratio is not 1: 1. If control is performed using such signals, accurate control becomes difficult,
Control can even be lost.

Therefore, in the present invention, as a second characteristic point, as shown in FIG.
It is larger than the width Lm of the magnetic poles 54 in the arrangement direction, preferably at least 1.01 times the width Lm of the magnetic poles 54 in the arrangement direction, and smaller than twice the width Lm of the magnetic poles 54 in the arrangement direction. By setting the relationship between the interval Ls between the magnetic poles 54 and the width Lm of the magnetic poles 54 as described above, as shown in FIG.
By compensating for the asymmetry of the electric signal a output from the controller, an electric signal suitable for control with a duty ratio of 1: 1 can be obtained.

Further, the thickness of the magnetic pole 54 is set to the width Lm in the arrangement direction.
By making it equal to or larger than the ratio, the ratio of the magnetic force lines in the direction in which the magnetic poles 54 are arranged is greater than the ratio of the magnetic force lines in the direction perpendicular to the direction in which the magnetic poles 54 are arranged. As the ratio of the lines of magnetic force in the direction in which the magnetic poles 54 are arranged increases, the number of lines of magnetic force detected by the converting means 58 that shifts in the direction in which the magnetic poles are arranged opposing each magnetic pole 54 increases. The amplitude increases and signal processing becomes easier.

Further, in the present invention, since the polarities of the magnetic poles in the magnetic pole row may be the same as described above, it is not necessary to magnetize the S pole and the N pole alternately as in the prior art, and the magnetizing work is extremely difficult. It's easy. The relationship between the outer shape of the base and the arrangement direction of the magnetic poles is such that, when the base is formed in a disk shape, the magnetic poles are arranged on the same circumference around the rotation axis of the base. When the outer shape of the base is formed in a long plate shape, the magnetic poles are arranged along the longitudinal direction of the base.

In the signal generator of the present invention using the above-described magnetic scale unit, the resolution of the magnetic scale unit is doubled with the same magnetization pitch as compared with the conventional one, so that the resolution is also doubled. Also, in the displacement detection device of the present invention, even if the relative displacement speed between the conversion means and the magnetic scale unit is the same, and even if the relative displacement amount is the same, the electric signal output from the signal generator is The number of included pulses is doubled, and the detection accuracy of the detectable displacement speed and displacement amount is doubled.

Further, in the motor control device according to the present invention, the resolution of the magnetic scale unit is doubled even if the magnetizing pitch is the same as before, so that the relative displacement speed between the conversion means and the magnetic scale unit is reduced. Even if the amount of displacement is the same or the amount of relative displacement is the same, the number of pulses contained in the electric signal output from the signal generator is doubled, and the detectable displacement speed and the accuracy of detecting the amount of displacement are doubled. In addition, the control of the number of rotations of the motor can be performed with twice the accuracy.

Hereinafter, preferred embodiments of a magnetic scale unit according to the present invention, a signal generator using the magnetic scale unit, a displacement detection device, and a motor control device will be described in detail with reference to the drawings. First, the basic configuration of the magnetic scale unit will be described, and then the basic operation of the signal generator using the magnetic scale unit and the conversion means will be described.

First, the magnetic scale unit 10 of the present invention
As shown in FIG. 1, the basic structure of the device comprises a base 52 made of a non-magnetic material and a plurality of magnets 12 arranged on the end side of the base 52. Each magnet 12 is like a Hall element. The magnetic poles 54 facing the conversion means 58 are arranged at a predetermined pitch λ along the moving direction of the conversion means 58 so that the polarities of the magnetic poles 54 facing each other have the same polarity (N pole in FIG. 1). In addition, each magnet 12 is configured such that its own N pole and S pole are arranged in a direction orthogonal to the arrangement direction of the magnets 12 (also the moving direction of the conversion means).

Here, the nonmagnetic base 5 made of resin or the like is used.
In order to arrange the magnets 12 in the magnet 2, for example, as shown in FIG. 3 (a), recesses 13 corresponding to the outer dimensions of the magnets 12 are formed in advance at the magnet arrangement positions of the base body 52 at a predetermined pitch λ. The magnet 12 may be fitted into the recess 13.
Although not shown, a through hole corresponding to the outer dimensions of the magnet 12 is formed in place of the recess 13, and the magnet 1 is inserted into the through hole.
2 is also available. Incidentally, in these cases, the thickness d of the magnet 12 is not restricted to the thickness d ₀ of the substrate 52. Further, the N pole of each magnet 12 is not exposed on the end face of the base 52 facing the conversion means 58, and the lines of magnetic force output from the N pole of each magnet 12 pass through the base 52 on the movement path of the conversion means 58. Reach

As another structure, as shown in FIG. 3B, the conversion means 58 is previously placed on the magnet placement position of the base 52.
There is a structure in which notches 15 reaching the end face facing the above are formed side by side at a predetermined pitch λ, and a magnet 12 having the same length as the notch 15 is fitted in the notch 15. In the case of this structure, the magnetic pole (N pole in the figure) 54 of the same polarity of each magnet 12 is exposed on the end face of the base 52 facing the conversion means 58. When arranging a plurality of magnets 12 in the base 52 made of a non-magnetic material in this way, a permanent magnet that has been magnetized in advance may be fitted into the recess 13 or the cutout 15 of the base 52, After attaching the magnet 12 to the notch 15 or the notch 15, the magnetizing process may be performed in one direction. Also,
After filling the concave portion 13 or the cutout portion 15 of the base 52 with the magnetic material, the magnetic material can be realized by performing a magnetizing process.

Further, although the magnetic scale unit 10 in FIG. 3 is a block N and S poles of each magnet 12 is arranged in the direction perpendicular to the thickness d ₀ direction of the base 52, for example, as shown in FIG. 4, arranged magnets 12 in the substrate 52 as N poles and S poles of each pole 12 are arranged in the thickness d ₀ direction of the base 52, the same on one surface of the substrate 52 polar (N on the surface in FIG. 4
(Pole) only. In FIG. 4, since the notch 15 is formed in advance at the place where the magnet 12 is arranged, another polarity (S-pole) appears on the other surface. It is also possible to adopt a structure in which the other polarity is not exposed on the other surface by fitting the magnet 12 into the magnet. In the case of FIG. 4, the conversion means 58 is arranged so as to face one surface of the base 52 on which one magnetic pole (for example, N pole) of each magnet 12 appears, and a magnetic pole row composed of this one magnetic pole It moves along.

The above is a case where a plurality of magnets are arranged on a non-magnetic substrate. As shown in FIG. 5, the substrate 52 of the magnetic scale unit 10 is made of a magnetic material, and its magnetic poles should be formed. It is also possible to form a permanent magnet by magnetizing only a part and arrange the magnets 12 in the base 52. Also in this case, the distance between adjacent magnetic poles (magnetized regions) of the same magnetism is larger than the width of the magnetic poles in the arrangement direction and the second
It is formed smaller than twice. The magnetic poles forming the magnetic pole row of each magnet 12 formed by magnetization are magnetized in the same direction so as to have the same polarity.

According to the configuration in which the magnetic poles are formed on the base material of the magnetic material by magnetization, it is not necessary to form a concave portion or a notch portion in which the magnet is fitted in the base member 52. The magnetic poles of the magnets 12 formed by magnetizing have the S pole exposed on the back surface with respect to the surface where the N pole is exposed as shown in FIG. 5, and the magnetic scale unit 10 shown in FIG. In some cases, both the N pole and the S pole are exposed on the same surface of the base 52.

The outer shape of the substrate may be formed in a long plate shape or a disc shape depending on the use of the magnetic scale unit. For example, when detecting the displacement amount and displacement speed of a moving body that moves linearly, a long plate-like base 52 as shown in FIG. 6 is used, and each magnetic pole 54 is formed along the longitudinal direction of the base 52. I do. Further, the magnetic scale unit 10 is arranged so that the longitudinal direction is parallel to the moving direction (the direction of the arrow) of the moving body, and the converting means 58 is provided.
Are arranged facing the magnetic pole row of each magnetic pole 54.

When detecting the rotational speed of the motor for driving the moving body, as shown in FIG. 7, the base 52 is formed in a disk shape, and the center of the body 52 is connected to the output shaft of the motor (not shown). ) And a rotating shaft X such as a gear rotated by a motor. In this case, the magnetic pole row 5 of each magnetic pole 54
8 are arranged on the same circumference having a radius R centered on the rotation axis X of the base 52 as shown in FIG. 8 in which the portion A of FIG. 7 is enlarged, and each magnetic pole 54 is exposed on the end face of the base 52. It does not have to be exposed or exposed. In the case where the moving body is displaced in an arc shape, the outer shape of the magnetic scale unit 10 may be formed in a disk shape or an arc shape, and a magnet may be arranged only at a necessary portion, although not shown. it can.

In the magnetic scale unit 10 of the present invention configured as described above, as shown in FIG. 1, the magnetic force lines b output from the magnetic poles 54 (for example, N poles) constituting the magnetic pole row 56 draw a loop. It goes to the opposite pole (S pole) formed on the opposite side of the same magnet 12, but since the magnetic poles 54 constituting the magnetic pole row 56 have the same polarity, each magnetic pole where the loop of the magnetic field lines b from the adjacent magnetic poles 54 gathers A place where the magnetic flux density becomes high also occurs in the middle part of 54. Therefore, two loops of the line of magnetic force b are formed between the adjacent magnetic poles 54.

Next, a signal generator using the above-described magnetic scale unit will be described. First, the signal generator 1
4 is provided opposite the magnetic scale unit 10 and the magnetic pole array 56 of the magnetic scale unit 10 as shown in FIGS. And conversion means 58 for converting. One of the magnetic scale unit 10 and the conversion means 58 is directly or indirectly attached to a moving body such as a head, a carriage for driving the head, or an output shaft of a motor, and is displaced and fixed to the other. And a relative displacement between them is generated.

In the signal generator 14, when the magnetic scale unit 10 and the converting means 58 are relatively displaced, the converting means 58 is displaced so as to cross the magnetic force lines b of the magnetic poles 54 of the magnetic scale unit 10. As described above, since there are two loops of the magnetic field lines b between the adjacent magnetic poles 54 and a place where the magnetic flux density is high also occurs in the middle part of the adjacent magnetic poles 54, the electric signal output from the conversion means 58 1 has a waveform as shown in FIG. 1, and the amplitude of the electric signal a has a peak at a position facing the front of each magnetic pole 54 and at an intermediate position between the adjacent magnetic poles 54. That is,
When the conversion means 58 moves between the adjacent magnetic poles 54,
Two peaks, twice that of the conventional example, are included in the electric signal. Therefore, even when the electric signal a is rectified into the pulse wave c shown in FIG. 1, twice as many pulses (two pulses) as between the conventional magnetic poles 54 can be obtained between the adjacent magnetic poles 54. Even if the pitch between them is the same, twice the resolution can be obtained.

The pulse wave c is usually further digitized (digitized), and thereafter, the number of pulses within a predetermined time is counted in order to detect the wave number, and the pulse wave c is detected in order to detect the displacement. Although the process of counting the number is performed, it is particularly desirable that the intervals between the respective pulses when digitized are equalized in order to increase the accuracy of the process of detecting the displacement amount serving as a reference for positioning or the like. .

For this purpose, it is necessary that each loop of the two lines of magnetic force b generated between the adjacent magnetic poles 54, which is the source of the pulse wave c, has a line symmetry and the same waveform. In order to make the waveform of the loop of each line of magnetic force b a line-symmetric waveform, as shown in FIG. 1, the interval Ls between the magnetic poles 54 of the same polarity of each magnet 12 arranged on the base 52 is determined by the direction of arrangement of the magnetic poles 54. May be larger than the width Lm. That is, since the signal is generally large at the position facing the magnetic pole 54, the symmetry of the signal is broken in the above-described configuration of Ls = Lm shown in FIG. 2 and the duty ratio is shifted from 1: 1. According to the present invention, symmetry of a signal can be ensured by setting Ls> Lm. The interval Ls between the magnetic poles 54 is preferably equal to or greater than 1.05 of the width Lm of the magnetic poles 54. However, if the width Lm is too large, the symmetry of the signal is lost.

As shown in FIG. 3B, the magnetic force lines b output from the magnetic poles 54 (N poles) of the magnets 12 facing the conversion means 58 are output in the direction of the moving path of the conversion means 58. is, magnetic force lines b ₁ to return to the non-magnetized areas adjacent drawing a curve, but is output toward the movement path direction of the converting means 58, the corresponding opposite poles (S pole) of each magnet 12 depicts a curve It is roughly divided into two field lines b ₂ Back to. The magnetic field lines that are actually detected by the converting means 58 because it is the magnetic field lines b _1, it is desirable magnetic force lines b ₁ is greater than the magnetic force line b _2. Therefore, by setting the thickness d of the magnet 12 (= the thickness of the magnetic pole) to be equal to or more than the width Lm of the magnetic pole, the direction of the arrangement of the magnetic poles 54, that is, the direction of the moving path of the conversion means 58, is closer to the magnetic force line b ₂ returning to the opposite pole. it can be increased proportion of magnetic field lines b _1.

The waveform of the electric signal a in FIG. 1 is a case where a Hall element is used for the conversion means 58.
FIG. 9 shows the waveform of the electric signal a when a MR sensor is used as a solid line. This electric signal a is the FG of the MR sensor.
1, which is output when the conversion means 58 moves between adjacent magnetic poles 54 because the electric signal originally contains twice as many peaks in the electric signal as compared with the case where the Hall element is used. The number of peaks in the electrical signal is four,
That is, the number of pulses is four. Even when this MR sensor is used, it is needless to say that a peak twice as large as that of the conventional signal generator is included in the electric signal.

Next, a displacement detecting device using the signal generator 14 will be described. The displacement detection device 16 is shown in FIG.
As shown in FIG. 0, the signal generator 14 including the magnetic scale unit 10 and the conversion unit 58 supplies the relative displacement amount and / or the relative displacement between the magnetic scale unit 10 and the conversion unit 58 by the electric signal a from the signal generator 14. It is provided with a calculating means 18 for detecting the speed. In the specific example of FIG. 10, the conversion unit 58 is attached to the moving body 20 and moves along the magnetic pole row 56 in the direction of the arrow along the magnetic pole row 56 while facing the magnetic pole row 56 formed on the magnetic scale unit 10.

The calculating means 18 includes a counter (not shown) for counting the number of pulses included in the input electric signal a, and a relative displacement y and / or a relative displacement based on the counter value n of the counter. And a computer for calculating the speed v. For example, when calculating the relative displacement y, the computer previously stores the unit distance data m for one pulse, multiplies the counter value n by the unit distance data m, and calculates the relative displacement y (= n × m). calculate. Also, when calculating the relative displacement velocity v counts the number of pulses included in the electric signals per unit time in the counter, have a function to output a unit counter value n _s, the unit counter value n is a computer _s is multiplied by the unit distance data m and the relative displacement y per unit time
By calculating (= _ns × m), the relative displacement amount y becomes the relative displacement speed, and the relative displacement speed is obtained.

In the specific example of the displacement detecting device shown in FIG. 10 described above, the case where the converting means 58 is attached to the moving body 20 and relatively displaced with respect to the magnetic scale unit 10 has been described. In the case of the magnetic scale unit 10 using the disk-shaped substrate 52 as described above, for example, the magnetic scale unit 10 itself is displaced (rotated) by attaching the magnetic scale unit 10 to an output shaft of a motor. 58 may be fixedly arranged at a position facing the magnetic pole row 56 of the magnetic scale unit 10.

Next, the motor control device of the present invention will be described. The motor control device is provided in a disk device such as an optical disk device or a magnetic disk device, and controls a spindle motor for rotating the disk to rotate the disk at a constant rotation speed, and CAV control for reproducing data from the disk with a head. It is mainly used for CLV control for rotating a disk so that the transfer speed of the disk is constant. In addition to the above-described disk devices, machine tools such as drilling machines and milling machines, audio equipment such as VTRs and CD players, and information devices such as external storage devices including the above-described disk devices are almost always used. Motors are used, and these motors are usually controlled in rotation speed so as to reach a target rotation speed.

The higher the precision of the motor speed control, the higher the quality of the product processed by the machine tool and the higher the performance of the audio equipment and the information equipment itself. Accuracy is desired. Therefore,
If the magnetic scale unit of the present invention is used for controlling the number of rotations of these motors, as described above, even if the pitch of each magnetic pole of the magnetic pole row is the same as the conventional one, the number of pulses included in the electric signal output from the conversion means Is doubled, and therefore the resolution is doubled, so that there is an effect that the number of rotations can be controlled with twice the accuracy.

A specific example of the motor control device according to the present invention will be described with reference to FIG. This motor control device 42
Controls the number of revolutions of the spindle motor 28 of the disk drive.
The magnetic scale unit 10 is attached to the center of the output shaft 28a of the spindle motor 28 so as to rotate integrally therewith. The conversion means 58 is fixed at a position facing the magnetic pole row 56 formed on the same circumference of the base 52 of the magnetic scale unit 10. Note that the magnetic scale unit 10 does not necessarily need to be directly attached to the output shaft 28a. If another unit (for example, a gear of a reduction mechanism) is rotated by the output shaft 28a, the magnetic It can be converted to a number. The driving means 38 drives the spindle motor 28.

The calculating means 18 detects the number of pulses contained in the electric signal from the converting means 58 and counts the number of pulses. The calculating means 18 operates between the magnetic scale unit 10 and the converting means 58 based on the counter value n of the counter. And a computer for calculating the relative displacement speed v of As described above, the relative displacement speed v is obtained by detecting the relative displacement amount y per unit time. Further, if the relative displacement speed v is known, the rotation speed of the magnetic scale unit 10 can be determined. , That is, the rotation speed of the output shaft 28a of the spindle motor 28 is also obtained. The control means 40 is constituted by a microcomputer or the like, controls the drive means 38 based on the rotation speed of the output shaft 28a detected by the calculation means 18, and controls the rotation speed of the output shaft 28a to a desired rotation speed. .

[0047]

According to the present invention, by forming the magnetic pole row with a plurality of magnetic poles having the same polarity, the pulse included in the electric signal output from the conversion means can be obtained without making the magnetization pitch narrower than before. The number can be doubled, and the resolution of the magnetic scale unit can be doubled with the same magnetized pitch as compared with the conventional one. In addition, by setting the interval between the magnetic poles to be larger than the width in the arrangement direction of the magnetic poles and smaller than twice the width, a signal with excellent symmetry can be obtained, so that the control using the magnetic scale unit can be more accurately performed. Can be done.

In particular, when the substrate is a disk like a magnetic scale unit used in a motor control device, the magnetic pole pitch must be reduced to 1/2 in the conventional configuration in order to double the resolution. However, this makes it difficult to form magnetic poles such as magnetizing work, increasing the manufacturing cost. In addition, unless the magnetic pole pitch is changed, it is necessary to double the distance of the magnetic pole row from the center of the base. According to the present invention, the resolution can be doubled without changing the outer shape of the magnetic scale unit and the pitch of the magnetic poles. Further, since the polarities of the magnetic poles in the magnetic pole row may be the same, it is not necessary to alternately magnetize the S pole and the N pole as in the related art, thereby simplifying the magnetizing operation.

Further, a signal generator used for detecting the displacement amount and the displacement speed using the magnetic scale unit of the present invention, and a displacement detecting device provided with this signal generator for detecting the displacement amount and the displacement speed are provided. With this configuration, the detection accuracy of the detectable displacement speed and the amount of displacement can be doubled as compared with the related art, and accurate signal processing can be performed.

Further, by using the magnetic scale unit of the present invention in a motor control device for controlling the number of rotations of a motor, the accuracy of the number of rotations of the motor can be reduced while maintaining the same pitch of the magnetic poles of the magnetic scale unit. As a result, the number of rotations can be controlled more accurately.

[Brief description of the drawings]

FIG. 1 shows a basic configuration of a magnetic scale unit according to the present invention;
FIG. 4 is an explanatory diagram showing a waveform of an electric signal output from the conversion unit when the magnetic scale unit and the conversion unit (Hall element) are relatively displaced.

FIG. 2 is an explanatory view showing a magnetic scale unit in which the interval between magnetic poles is equal to the width of the magnetic poles, and a waveform of an electric signal output from a conversion unit.

3A and 3B are perspective views of main parts showing a structure for mounting a magnet on a base of a magnetic scale unit, wherein FIG. 3A shows a case where a magnet is fitted into a concave portion of the base, and FIG. The case of fitting is shown.

FIG. 4 is a perspective view of a main part showing another mounting structure of the magnet on the base of the magnetic scale unit, showing a case where magnetic poles of the magnet are arranged in a thickness direction of the base.

FIG. 5 is a perspective view of a main part showing another mounting structure of the magnet on the base of the magnetic scale unit, in which the magnet is formed by magnetizing such that the magnetic poles of the magnet are arranged in the thickness direction of the base. Show.

FIG. 6 is a perspective view showing a specific example of a long plate-shaped magnetic scale unit.

FIG. 7 is a perspective view showing a specific example of a disk-shaped magnetic scale unit.

FIG. 8 is an enlarged view of a portion A in FIG. 7;

FIG. 9 shows a magnetic scale unit and conversion means (MR element).
FIG. 9 is an explanatory diagram showing a waveform of an electric signal output from the conversion unit when and are relatively displaced.

FIG. 10 is a block diagram showing a basic configuration of a displacement detection device using the magnetic scale unit of the present invention.

FIG. 11 is a block diagram showing a basic configuration of a motor control device using the magnetic scale unit of the present invention.

FIG. 12 shows a basic configuration of a conventional magnetic scale unit,
FIG. 4 is an explanatory diagram showing a waveform of an electric signal output from the conversion unit when the magnetic scale unit and the conversion unit (Hall element) are relatively displaced.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Magnetic scale unit 12 Magnet 14 Signal generator 16 Displacement detection device 20 Moving body 42 Motor control device 52 Base 54 Magnetic pole 56 Magnetic pole row 58 Conversion means

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F063 AA02 AA35 BA30 BD15 BD16 CA09 DA05 EA02 EA03 GA52 GA64 GA65 GA66 GA67 GA72 KA02 KA04 5D088 BB02

Claims (7)

[Claims] 1. A magnetic scale unit having a magnetic pole array in which a plurality of magnetic poles are arranged at equal intervals at intervals on a substrate, wherein the magnetic poles have the same polarity, and the interval between the magnetic poles is a width in an arrangement direction of the magnetic poles. A magnetic scale unit, which is larger and smaller than twice the width of the magnetic poles in the arrangement direction. 2. The magnetic scale according to claim 1, wherein the base is a non-magnetic material, and the magnetic poles are constituted by magnetic poles of the same polarity of a permanent magnet disposed in the base. unit. 3. The magnetic scale unit according to claim 1, wherein the base is a magnetic material, and the magnetic poles are formed of magnetic poles of the same polarity formed by magnetizing the base. 4. The magnetic recording medium according to claim 1, wherein the base is a disk, and a plurality of magnetic poles are arranged on the same circumference around a rotation axis of the base. A magnetic scale unit according to any one of the above. 5. A magnetic scale unit according to claim 1, wherein the magnetic scale unit is provided so as to face a magnetic pole row of the magnetic scale unit, and converts a change in a magnetic field due to a relative displacement with the magnetic scale unit into an electric signal. A signal generator comprising: a conversion unit. 6. A signal generator according to claim 5, and a calculation means for detecting a relative displacement amount and / or a relative displacement speed between the magnetic scale unit and the conversion means based on an electric signal from the signal generator. A displacement detection device characterized by the above-mentioned. 7. The magnetic scale according to claim 4, wherein the rotating shaft of the disk-shaped substrate is directly or indirectly attached to the output shaft of the motor, and the disk-shaped substrate rotates with the rotation of the output shaft. A drive unit for driving the motor, and a magnetic pole unit of the magnetic scale unit, which is provided opposite to the magnetic pole unit, and converts a change in a magnetic field due to a relative change between the magnetic scale unit and the rotation of the output shaft into an electric signal. Converting means; calculating means for detecting the rotational speed of the output shaft based on the electric signal from the converting means; and determining that the rotational speed of the output shaft is a desired rotational speed based on the rotational speed of the output shaft detected by the calculating means. Control means for controlling the driving means of the motor so that the number of the motors becomes equal to the number of motors.