JPH0254481A - Magnetic head positioning device - Google Patents

Abstract

PURPOSE:To prevent the title device from increasing in size and to improve the accuracy by moving a magnetic scale unit and a magnetoelectric converting means relatively as a carriage moves and positioning them according to the output of the electromagnetic converting means. CONSTITUTION:A head assembly 12 where a magnetic head 11 is mounted is fixed to the carriage 13. This carriage 13 is arranged on a linear guide 14 slidably as shown by an arrow. The magnetoelectric converter 15 is fixed on the flank of the carriage 13. Further, a magnet scale unit 16 is arranged nearby the flank of the guide 14 opposite the converter so that the carriage 13 moves lengthwise. The unit 16 consists of magnet scales 16a and 16b and S and N poles are magnetized in the scales 16a and 16b alternately at pitch lambda. Further, the scales 16a and 16b are arranged in parallel while shifting in magnetization position by a distance lambda/16. Consequently, the resolution of the position detection of the magnetic head can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a magnetic head positioning device used in, for example, a magnetic disk device that records or reproduces information on a magnetic disk.

(Prior Art) In conventional magnetic disk devices, especially hard disk drive devices, a disk-shaped magnetic disk is rotated at high speed by a spindle motor, and magnetic disks formed concentrically on the surface of this high-speed rotating magnetic disk are used. Information is recorded on the track or information recorded on the track is reproduced by driving a magnetic head as a recording/reproducing means close to the track.

In such magnetic disk drives, a stepping motor or a voice coil motor is generally used as a drive source for moving a magnetic head to a target track.

The above stepping motor has a slow access time, but the motor itself is equipped with a position (angle) detection mechanism, and
Because they are cheaper than other motors, they are often used in small-diameter magnetic disk drives.

On the other hand, although the voice coil motor is suitable for high-speed access and is employed in large-capacity magnetic disk drives, it does not include a position detection mechanism.

Therefore, a control system called a so-called surface servo system is usually employed to detect the position of the magnetic head. That is, in addition to the magnetic disk used for recording and reproducing data, a magnetic disk dedicated to position and speed control is provided, and servo information is obtained from this magnetic disk to detect position and speed.

However, providing a magnetic disk exclusively for control other than for recording and reproducing such data is difficult to implement in a small-diameter magnetic disk device, and is also disadvantageous in terms of cost.

Therefore, in recent years, DC servo motors and magnetic scales (
A system has been developed that detects the position and speed of a magnetic head using a position/speed detection mechanism consisting of a magnetic head (magnescale) and an MR element (magnetoelectric element).

For example, FIG. 8 shows a linear magnetic head drive mechanism. In the figure, reference numeral 1 denotes a magnetic disk as a recording medium, which is rotated at high speed by a spindle motor (not shown). A magnetic helad 3 is mounted on the tip of the head assembly 2, and the head assembly 2 itself is fixed to a carriage 4, and the carriage 4 is arranged to be slidable with respect to a linear guide 5. . In addition, the pinion 6 is connected to a DC servo motor 7.
It is fixed to the rotating shaft of the carriage 4, and meshes with a rack 8 provided on the side of the carriage 4. Then, the carriage 6 slides on the linear guide 5 as the pinion 6 is rotationally driven by the DC servo motor 7.
As a result, the magnetic head 3 is moved along the surface of the magnetic disk 1 in the direction of the arrow shown in the figure, and is moved to a target track.

A disc-shaped magnetic scale (Magnescale) 9 is attached to the rotating shaft of the DC servo motor. The outer periphery of the magnetscale 9 is magnetized so that S poles and N poles appear alternately at a predetermined pitch. Further, a magnetoelectric transducer 10 consisting of a magnetoelectric element (MR element) is provided near the outer circumference of the magnetescale 9, and detects changes in the magnetic field accompanying the rotation of the magnetescale 9, thereby controlling the magnetic head 3. It is designed to detect position and velocity.

Further, as another conventional magnetic head drive mechanism, one based on a rotary system is shown in FIG. In the figure, reference numeral 1 denotes a magnetic disk as a recording medium, which, like the above, is rotated at high speed by a spindle motor (not shown). The carry nozzle 4a is rotatably provided around a rotating shaft 4b, and a magnetic head 3a is mounted on one end thereof via a head assembly 2a, and a rack 8a is provided on the other end. It is being Further, the pinion 6a is fixed to the rotating shaft of the DC servo motor 7a, and meshes with the rack 8a.

Then, the carriage 4a rotates about the rotating shaft 4b as the pinion 6a is rotationally driven by the DC servo motor 7a, and the magnetic head 3a is moved along the surface of the magnetic disk 1 in the direction of the arrow shown in the figure. It is now possible to move the track to the desired track.

At a distance from the magnetic head 3a at one end of the carriage 4a, an arcuate magnet scale 9a is attached, which is magnetized so that S poles and N poles appear alternately at a predetermined pitch. Also, near this Magnescale 9a, M
A magnetoelectric transducer 10a consisting of an R element is provided to detect changes in the magnetic field accompanying rotation of the magnet scale 9a integrated with the carriage 4a, thereby detecting the position and speed of the magnetic head 3a. There is.

In order to improve the resolution of detecting the position and speed of the magnetic head 3.3a as described above, the diameter of the magnescale 9 is increased in the case of a linear system, and the diameter of the magnescale 9a is moved away from the rotating shaft 4b in the case of a rotary system. Attempts are being made to install it in a different location. Although detection resolution can be improved with such a configuration, on the other hand, the inertia (moment of inertia) of Magnescale 9.9a increases,
This has the disadvantage of reducing access time. Furthermore, increasing the diameter of the Magnescale 9 or disposing the Magnescale 9a at a position distant from the rotating shaft 4b requires a considerable amount of space, and there is also the drawback that the device cannot be miniaturized.

Further, the magnetoelectric transducer 10.10a is constructed of four-element, two-phase MR elements, as shown in FIG. 10, for example. That is, Magnescale 9.
With respect to the magnetization pitch λ of 9a, each MR element is arranged at a spacing of λ/4, and two MR elements at a spacing of λ/2 are connected to each other to obtain outputs E1 and E2 at the intermediate portions of each. Then, the phase difference between these output signals is λ/4 (90 degrees), as shown in Fig. 11, and the magnetic scale is 9.9.
A signal with accuracy equivalent to dividing the magnetization pitch λ into four on a can be obtained.

On the other hand, when trying to improve the recording capacity of a magnetic disk, it is necessary to improve the track density, and correspondingly, the magnetization pitch λ of the Magnescale 9.9a described above must be decreased or the number of MR elements must be increased. Increase the magnetization pitch λ
It is necessary to increase the number of divisions.

The above-mentioned magnetization pitch λ is currently limited to 200p, and it is difficult to magnetize with a pitch larger than this. In addition, as an example of increasing the number of divisions, for example,
There is an example in which an 8-element, 4-phase MR element is used with the magnetization pitch λ divided into 8, but if the number of elements is increased further in the direction of the magnetized column, the difference between the MR element and Magnescale will be reduced. There is a drawback that the separation distance varies depending on the elements, making accurate positioning impossible. This is particularly noticeable in the case of a rotary system.

(Problems to be Solved by the Invention) As described above, this invention improves the detection resolution by increasing the diameter of the magnetic scale or by providing it at a position away from the rotation axis. increases, leading to a decrease in access time, and
This eliminates the drawbacks of requiring a considerable amount of space and making it impossible to miniaturize the device, as well as the inability to improve the resolution of position and speed detection due to improved track density on magnetic disks. It is an object of the present invention to provide a magnetic head positioning device that can improve the resolution of detecting the position and speed of a magnetic head while preventing a decrease in access time and a decrease in access time.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, a magnetic head positioning device of the present invention includes a carriage for transporting a magnetic head for recording and reproducing information, and a predetermined magnetized a magnetic scale unit comprising a plurality of magnetic scales magnetized alternately with opposite polarities at a pitch so as to have a predetermined phase difference; magneto-electric conversion means for converting changes in the magnetic field due to relative movement with the magnetic scale unit as the carriage moves into electric signals; and positioning by detecting the position and speed of the magnetic head using the electric signals from the magneto-electric conversion means. Further, for the same purpose, a carriage for transporting a magnetic head for recording and reproducing information, and a carriage that is alternately magnetized with opposite polarities at a predetermined magnetization pitch. A magnetic scale is disposed facing the magnetized surface of the magnetic scale so as to have a predetermined phase difference, and changes in the magnetic field due to relative movement with the magnetic scale accompanying movement of the carriage are electrically detected. It is characterized by comprising a magneto-electric conversion module consisting of a plurality of magneto-electric transducers that convert it into signals, and a control means that detects the position and speed of the magnetic head and performs positioning based on the electric signals from the magneto-electric conversion module. .

(Function) This invention provides a magnetic scale unit in which a plurality of magnetic scales are arranged so as to have a predetermined phase difference, and a magnetic scale unit in which a magnetic head is positioned at a target position by moving a carriage. The magnetic head is moved relative to the magneto-electric transducer provided oppositely as the carriage carrying the magnetic head moves, and the magnetic head is moved based on a signal obtained from the magneto-electric transducer as a result of this relative movement. It detects distance and speed and performs positioning. By setting the above predetermined phase difference to be smaller than the phase difference of the signal obtained in the case of a single magnetic scale, positioning can be performed with a resolution equal to the phase difference of the plurality of magnetic scales. .

Further, by providing only one set of the magnetic scales and providing a plurality of magnetoelectric conversion means facing the same so that they coexist in a predetermined phase, the same effect as above can be obtained. produce an effect.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows the main parts of a linear magnetic head drive mechanism. A head assembly 12 on which a magnetic head 11 is mounted is fixed to a carriage 13. The carriage 13 receives driving force from a C servo motor (not shown) as shown in the conventional example, and is disposed so as to be slidable on a linear guide 14 in the direction of the arrow in the drawing. Note that the motor for driving the carriage 13 is not limited to a DC servo motor, but may be a voice coil motor. Further, on the side surface of the carriage 13, a magneto-electric transducer (magneto-electric transducer) 1 consisting of an MR element is provided.
5 is fixed.

Further, near the side surface of the linear guide 14, a magnet scale unit (magnetic scale unit) 16 whose longitudinal direction is the moving direction of the carriage 13 is arranged so as to face the magnetoelectric transducer 15.

The Magnescale unit 16 is shown in FIGS. 2 and 3.
As detailed in the figure, it is composed of two rows of Magnescales 16a and 16b, and each Magnescale 16
The magnets a and 16b are magnetized so that S poles and N poles appear alternately at a pitch λ. In addition, the first Magnescale 1
As shown in FIGS. 3 and 4, the magnet scale 6a and the second magnet scale 16b are arranged in parallel with their magnetized positions shifted by a distance of λ/16.

The magnetoelectric transducer 15 is disposed so as to be movable in the directions of the arrows shown in FIGS. 1 and 2, and by moving opposite to the first magnescale 16a and the second magnescale 16b, respectively. It outputs a magneto-electrically converted signal. Further, the magnetoelectric converter 15 has 8
It is composed of four-phase MR elements a to h, and the third
As shown in the figure, the first and second magnescales 16
For the magnetization pitch λ of a and 16b, each MR element is
/4 spacing, and two M at λ/2 spacing.
Connect the R elements and output E1 ~ at the middle part of each
It is now possible to obtain E4. Each of these output signals E1
The phase/difference between ~E4 is λ/8 (45 degrees), and a signal with accuracy equivalent to dividing the magnetization pitch λ into 8 on the first magnet scale 16a can be obtained. Fifth
The figure shows the connection state of each MR element a to h of the magnetoelectric converter 15.

Similarly, each of the output signals E1 to E4 has a phase difference of λ/8 (45 degrees) on the second magnet scale 16b.
A signal with accuracy equivalent to dividing the magnetization pitch λ into 8 can be obtained.

The magnetization pitch λ obtained when the magnetoelectric transducer 15 moves opposite to each magnescale 16a or 16b
A signal with an accuracy equivalent to dividing into 8 is the same signal obtained by a conventional 8-element 4-phase magnetoelectric converter. However, since the first magnescale 16a and the second magnescale 16b are arranged with a shift of λ/16, the magnetoelectric converter 15 is connected to the first magnescale 16a.
By combining the signals E1 to E4 obtained when moving facing the second magnet scale 16b and the signals E1 to E4 obtained when moving facing the second magnet scale 16b, using a control means (not shown), It is designed to generate a signal having a phase of λ/16. As a result, the magnetization pitch λ is set to 16
It is possible to obtain a signal with an accuracy equivalent to that obtained by dividing the signal into equal parts.

As a result of the above, the resolution can be improved to twice that of the conventional method, and therefore the positioning resolution of the magnetic head can be improved twice as much. Furthermore, since it is possible to suppress an increase in the moment of inertia of the head access system, the access time does not decrease and the apparatus does not become large.

When using the sector servo method, since the servo track is located in the middle of the data tracks, for example:
The magnetic scale 16a is adapted for the servo track, and the second magnetic scale 16b is adapted for the data track. When a disk manufacturer records servo data, the first magnetic scale 16a is used for positioning. Thereafter, the magnetoelectric transducer 15 is moved onto the second magnet scale 16b for use.

FIG. 6 shows the main parts of a rotary type magnetic head drive mechanism. The carriage 21 is rotatably provided around a rotating shaft 22, and a magnetic head 24 is mounted on one end of the carriage 21 via a head assembly 23, and a rack 25 is provided on the other end. There is.

Further, the pinion 26 is fixed to the rotating shaft of the DC servo motor 27 and meshes with the rack 25. When the pinion 26 is rotationally driven, the carriage 21 rotates about the rotating shaft 22, and the magnetic head 24 is moved to the magnetic disk 1 (not shown).
is rotated along the surface in the direction of the arrow shown in the figure to move it to the desired track.

Furthermore, an arc-shaped Magnescale unit 27 is attached to the inside and lower part of the carriage 21 . This Magnescale unit 27 is also composed of two rows of Magnescales arranged at a distance of λ/16, as in the linear type embodiment. Further, a magnetoelectric transducer 28 that is movable in the direction of the arrow shown in the figure is provided at a position facing the Magnescale unit 27, and detects changes in the magnetic field due to rotation of the Magnescale unit 27 integrated with the carriage 21. , thereby the magnetic head 24
It is designed to detect the position and velocity of the

With the above configuration, it works in the same way as the linear method described above, and it is possible to obtain a signal with accuracy equivalent to dividing the magnetization pitch λ into 16 equal parts. In other words, the resolution can be doubled, and therefore the positioning resolution of the magnetic head can be doubled.

Next, as shown in FIG. 7, the position/velocity detection mechanism using the above-mentioned Magnescale and MR element includes a magneto-electric conversion module 32 equipped with one row of Magne-scale 31 and two sets of magneto-electric transducers 32a and 32b. It can also be configured using

As shown in FIG. 7, the Magnescale 31 is magnetized so that S poles and N poles appear alternately at a pitch λ. The magnetoelectric conversion module 32 is configured to output a magnetoelectrically converted signal by moving opposite to the magnet scale 31. This magnetoelectric conversion module 32 has two sets of magnetoelectric transducers 32a and 32b each consisting of an 8-element, 4-phase MR element, which are arranged at a distance of λ/16 in the magnetized column direction (longitudinal direction) of the magnetescale 31. It was established. Each magnetoelectric transducer 32a132b has a third
As in the case of the linear type embodiment shown in the figure, each MR element is arranged at an interval of λ/4 with respect to the magnetization pitch λ of the magnet scale 31, and two MR elements at an interval of λ/2 are arranged. 7 to obtain outputs E1 to E4 at the respective intermediate portions. Therefore, the above output signals E1 to E obtained from the respective magnetoelectric transducers 32a and 32b
The phase difference of 4 is λ/8 (45 degrees), and a signal equivalent to dividing the magnetization pitch λ into 8 on the magnet scale 31 can be obtained.

Here, since the magnetoelectric transducer 32a and the magnetoelectric transducer 32b are arranged with a shift of λ/16, by combining the output signals E1 to E4 from each of the magnetoelectric transducers 32a and 32b, A signal with a phase of /16 is generated. This makes it possible to obtain a signal with accuracy equivalent to dividing the magnetization pitch λ into 16 equal parts.

In this case as well, the resolution can be doubled, and therefore the positioning resolution of the magnetic head can be doubled.

In the above embodiment, the case where the present invention is applied to a hard disk drive device has been described, but the present invention can also be applied to a magnetic head positioning device of a floppy disk device.

Furthermore, in the above embodiment, a case has been described in which the detection resolution is doubled by using two sets of Magnescales or two sets of magnetoelectric transducers, but the number of Magnescales or magnetoelectric transducers is limited to the above. It is also possible to further improve the detection resolution by using three or more sets of Magnescale or three or more sets of magnetoelectric transducers.

[Effects of the Invention] As detailed above, the present invention provides a magnetic head that can improve the resolution of position and speed detection of the magnetic head while preventing the device from increasing in size and reducing access time. A positioning device can be provided.

[Brief explanation of the drawing]

FIG. 1 to FIG. 5 show an embodiment of this invention.
Fig. 1 is a diagram showing the schematic configuration of the magnetic head drive mechanism;
The figure shows the configuration of the Magnescale unit, Figure 3 shows the arrangement of the MR element, Figure 4 shows the arrangement of the Magnescale, and Figure 5 shows the wiring state of the MR element. , FIG. 6 is a diagram showing a schematic configuration of a magnetic head drive mechanism of another embodiment, FIG. 7 is a diagram showing the arrangement of an MR element in another embodiment, and FIGS. 8 to 11 are diagrams showing a conventional implementation. FIG. 8 is a configuration diagram of a linear type magnetic head drive mechanism, FIG. 9 is a configuration diagram of a rotary type magnetic head drive mechanism, FIG. 10 is a diagram showing the arrangement of MR elements, and FIG. FIG. 11 is a diagram for explaining the output signal of the MR element. 11... Magnetic head, 12... Head assembly,
13... Carriage, 14... Linear guide, 15
--Magnetoelectric converter (magnetoelectric conversion means), 16A magnet scale unit (magnetic scale unit), 16a...
First Magnescale, 16b... Second Magnescale, 31... Magnescale (magnetic scale) 3
2... Magnetoelectric conversion module, 32a. 32b...Magnetoelectric converter. Applicant's Representative Patent Attorney Takehiko Suzue No. 6b Figures Figures Figures Figures Figures Figures Figures

Claims (2)

[Claims] (1) A carriage that transports a magnetic head that records and reproduces information and a plurality of magnetic scales that are alternately magnetized with opposite polarities at a predetermined magnetization pitch are arranged so that they have a predetermined phase difference. a magnetic scale unit comprising: a magnetic scale unit; and a magneto-electric conversion means provided opposite to a magnetized surface of the magnetic scale unit, for converting a change in a magnetic field due to relative movement with the magnetic scale unit as the carriage moves into an electrical signal. A magnetic head positioning device comprising: a control means for detecting the position and speed of the magnetic head and positioning the magnetic head using an electric signal from the magnetoelectric conversion means. (2) A carriage that transports a magnetic head for recording and reproducing information, a magnetic scale that is alternately magnetized with opposite polarities at a predetermined magnetization pitch, and a carriage that faces the magnetized surface of the magnetic scale. a magnetoelectric transducer, which is arranged to have a predetermined phase difference, and which converts changes in the magnetic field due to relative movement with the magnetic scale as the carriage moves into electrical signals; A magnetic head positioning device comprising: control means for detecting the position and speed of the magnetic head and positioning the magnetic head using an electric signal from a conversion module.