JPS62295278A - Head feeding mechanism - Google Patents

Abstract

PURPOSE:To attain the low cost for a feeding mechanism with high accuracy by making the magnetized region opposite in adjacent magnetized regions in the polarity direction of a magnetic field and using a ring member having a nonmagnetized region not magnetized between the magnetized region and its adjacent magnetized region. CONSTITUTION:The magnetized region (N S) comprising magnetic pole NS and the magnetized region (S N) comprising magnetic pole SN different from the direction of this magnetic field are formed alternately to the magnetizing ring 7 and a nonmagnetized part not magnetized exists between the magnetized regions. Each magnetized region corresponds to a stop position (track position) in each cam face 8. Since the magnetized region is applied as magnetic recording to a position of the ring member corresponding to a stop position (track position) in response to the radius of a cam face while using a jig for each cam with a sufficiently excellent accuracy than that of the cam face, the cam stop position accuracy is nearly the recording accuracy of a position information recording signal.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a magnetic head feeding mechanism in a magnetic disk device, and particularly in a device using a magnetic disk with a small diameter. This invention relates to a head feeding mechanism that accurately stops the head at a predetermined position on the disk surface.

[Conventional technology]

In conventional magnetic disk drives that use eccentric cams to feed the head, the relationship between the rotation angle and displacement of the cam is changed in stages to rotate the cam, as described in Japanese Patent Laid-Open No. 59-3752. It was designed to absorb errors in the stop position of the pulse motor.

[Problem that the invention seeks to solve]

However, the accuracy of the above-mentioned step directly affects the stopping position of the magnetic head, and a highly accurate cam is required.

The purpose of the present invention is to improve the shortcomings of the prior art, compensate for the accuracy of the cam, and make it possible to accurately stop the head at a predetermined stopping position without requiring high accuracy from the cam itself. The object of the present invention is to provide a low-cost head feeding mechanism.

[Means for solving problems]

The above purpose is to make the relationship between the rotation angle and displacement (head feed amount) of the cam approximately linear, and furthermore, to make the relationship between the rotation angle of the cam and the displacement (feed amount of the head) approximately linear, and also to make the rotation of the cam corresponding to the predetermined stop position (track position) where the magnetic head should stop near the outer periphery of the cam. A ring member is provided in which position information is recorded with sufficient accuracy in the form of a pH range, and as the cam rotates, the cam position is recorded on the ring. This is achieved by determining the stopping position of the cam based on this sensing and compensating for the accuracy of the cam.

In addition, the one sensing word obtained in the above sensing is such that the direction of the magnetic field in the magnetized area (stop position) as rotational position information is made to be opposite to each other for each adjacent stop position (track position), and This can be obtained by providing a non-magnetized region that is not magnetized between the attached region (track position) and the magnetized region (track position).

[Effect]

The magnetized area as the above position information recording signal corresponds to the stop position (track position) according to the radius of the cam surface using a jig etc. for each cam with sufficiently better accuracy than the accuracy of the cam surface. Since magnetic recording can be performed at a position on a ring member (a ring member provided on the outer circumference of the cam so as to rotate integrally with the cam), the cam stop position accuracy can be approximately the recording accuracy of the position information recording signal. .

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail.

FIG. 1 is a perspective view showing a schematic configuration of a head feeding mechanism as an embodiment of the present invention.

In the figure, 4 is a magnetic disk, and chassis 13
The disc motor 3 is mounted on a hub 12 provided on a rotating part of a disc motor 3 fixed to the disc motor 3, and rotates at a predetermined number of revolutions. 1
1 is a sensor fixed to the chassis 13.

On the other hand, the magnetic head 2 is fixed to the tip of the head carriage nozzle 1 and is in contact with the magnetic disk 4.

The head carriage 1 is guided by a guide shaft 18 and slides. The height and position of the guide shaft 18 are determined by attaching a presser plate 15 to height pins 14 fixed to the chassis 13 at both ends with screws 16. Therefore, the magnetic head 2 can move in the direction of the arrow 19.

The cam 6 has a rotation hole 9 concentrically with the disc motor 3 and is rotatably attached to the underside of the disc motor 3.
It is constructed as shown in FIG.

A gear 10 is integrally formed on the outer periphery of the cam 6 and meshes with a pinion gear 17 of a pulse motor 26. The side portion of the pin 5 fixed to the hand carriage 1 is in contact with the cam surface 8 with appropriate pressure.

The cam surface 8 is configured such that its radius of rotation increases as it rotates in the direction of the arrow 20. Therefore, as the cam 6 rotates in the direction of arrow 20, the magnetic head 2 moves in the direction of arrow 19 (from the inner circumference to the outer circumference of the magnetic disk 4).

The stroke of movement is 5 mm, and if the cam 6 is usually made of plastic material, the cumulative accuracy of the cam surface 8 will be about ±20 μm. Further, a magnetized ring 7 made of a magnetic material is press-fitted or bonded to the cam 6 as shown in the figure.

That is, when the cam 6 rotates around the rotation hole 9, the magnetized ring 7 rotates together with the magnetized ring 7. Here, the reduction ratio of the rotational speed from the pulse motor 26 to the cam 6 is set to 1:10, and in 10 steps of the pulse motor 26, the magnetic head 2 moves a distance of one track, that is, 100 μm.

On the other hand, the variation in the stop angle of the pulse motor 26 is usually about ±10% of one step angle. Therefore, the error in the stopping position of the magnetic head 2 largely depends on the accuracy of the cam surface 8.

Therefore, the method of compensating for this accuracy adopted in the present invention will be explained below.

FIG. 3 is a plan view of the cam showing the relative positional relationship between the cam surface 8 and the magnetized state of the slave ring 7. FIG. The number and position are the magnetic pole position in the ring 7 and the sensor 11.
FIG. 2 is an explanatory diagram showing the relative positional relationship among the position of the ferromagnetic thin film resistance element, the magnetic field distribution of the magnetized ring 7, and the sensing signal after waveform shaping of the signal obtained by the sensor 11.

That is, in FIG. 3, the magnetized ring 7 has a magnetized region (denoted as N-3) consisting of the magnetic pole NS, and a magnetized region (denoted as S) consisting of the magnetic pole SN having a different magnetic field direction. −
N) are formed alternately, and a non-magnetized thermally bonded portion exists between the magnetized regions. Each magnetized region corresponds to a stop position (track position) on the cam surface 8, respectively.

A sensor 11 is provided at a fixed position (chassis) with a gap of about 0.1 mm from the top surface of the magnetized ring 7. The sensor 11 consists of a ferromagnetic thin film resistance element (hereinafter abbreviated as MR element), and its specific resistance ρ is ρ=ρ
. −Δρ(H/Hs)2. Here, ρ. ,
Δρ is a constant value determined by the element material, etc., H is the signal magnetic field applied from the outside, H3 is the saturation magnetic field, which is also determined by the element material, etc., and ρ is the external (when the magnetic field H is applied, as shown in Figure 5) As shown, it exhibits bell-shaped characteristics.

In addition, as shown in Fig. 4 (as the sensor 11, two MR elements are arranged horizontally to the magnetized ring as shown in ① and ②), and the pinch between ⋅ and O is The circumference of the ring 7 is 243 μm, which corresponds to one step of a pulse motor.

Further, the magnetized width (length dimension of one magnetized region) of the magnetized ring 7 in the feeding direction is also set to approximately the same value. Therefore, M
When the cam rotates so that the R element is in the position shown in (3) in Fig. 4, if the electrical connections are made as shown in Fig. 6, the sensing signal from the sensor 11 becomes H level and the result is obtained. It will be done.

Here, the sensor 11 includes two MR elements ■.

Although the explanation has been made assuming that ◎ is used, this is merely for technical reasons, and in principle, it is sufficient to use only one element.

In addition, the magnetization of the magnetization ring-7 (the magnetization is the formation of a region) is as follows:
This can be done with a sufficiently good accuracy (±5 μm or more) compared to the accuracy of the cam surface 8 of ±20 μm, and at a position where the pulse motor 26 can be stopped.

This can be done at the stage where the cam 6 and the magnetized ring 7 have been assembled in advance using a jig or the like.

Here, the jig uses a magnetizing head to attach if! ring 7
Magnetization will be carried out, but the magnetization pattern at this time is shown in (2) of Figure 4, so that the direction of the magnetic field in each magnetized region is alternately opposite. A magnetized region is formed by switching the current of the magnetic head.

This means that (1) the magnetization of the magnetized ring 7 is stabilized as a whole because the magnetization polarity is different for every other ring, and (2) there is a non-magnetized region between each magnetized region. Therefore, there is less interference between the magnetized regions and the SN of the sensing signal is improved (3
) Prevents magnetization of the magnetizing head (alternately attaching with opposite polarity)
), it has advantages such as

Furthermore, since the magnetization pattern has a heat bonding area, the required power for the magnetization head can be reduced and heat generation of the magnetization head can be prevented.

Further, the number of magnetized regions in the magnetized ring 7 is set to be equal to the number of tracks on the disk surface (for example, 50). Here, the track position is the head feed stop position (
It goes without saying that this is the stop position on the cam surface.

In FIG. 4 (2), track numbers 0, 1° 2. (NS) and (SN) at the corresponding positions, respectively.

(NS) and a magnetized region are provided. In this way, one magnetized area is provided for each track, but for track number O, for convenience of cueing, an extra magnetized area is provided (41'6M area is EX).

As shown, the magnetized area (track number 0
(magnetized region corresponding to the magnetic field).

Here, as seen in FIG. 3, the difference between the maximum radius r2 and the minimum radius r1 of the cam surface 8 is the stroke of the magnetic head 2, and the effective rotation angle θ of the cam is 300°. Therefore, assuming that the number of tracks is 50, , the rotation angle per track is 6''.

Next, the track feeding operation will be explained.

In FIG. 4, in order for the magnetic head 2 to move from the track position of track number 0 to the track position of track number l, it is necessary for the pulse motor 26 to rotate by 10 steps, and the magnetic head 2 is O
When the MR element (sensor 11) is in the fourth position, the MR element (sensor 11)
In the position shown in figure (2), the sensed signal is at 1 lebel, as seen in (5).

At the start of the feed operation, the accuracy of the cam surface 8 is ±20 μm, and normally the pulse motor 26 should be sent in 10 steps, but it should be within ±22 steps. During this time, the sensing signal continues to be at the L level since the first step.

Thereafter, it is determined whether the sensing signal is high or low at that position, and the signal is sent one step at a time, and the pulse motor 26 is stopped at the position where it reaches the H level (in this example, the 10th step), thereby causing the magnetic head 2 to track. It is possible to accurately stop at the track number 1 position.

However, for the operation of sending one step at a time without determining the sensing signal, set an upper limit so that it is performed up to the 12th step, and if the sensing signal is at L level even after sending 12 steps, go back two steps and go back to the 10th step from the beginning. Pulse motor 2 at position
Stop 6.

This is a backup operation to prevent the feeding operation from being repeated infinitely if a sensing signal is not obtained for some reason. positioning.

Similarly, when moving to the second track, the pulse motor 26 stops at the position where the sensing signal (position information signal) becomes H level. Therefore, track number 0
The required rotation angle of the cam surface 8 from track number 1 to track number 1 and from track number l to track number 2 is as shown in FIG. 4 (1), that is, between tracks 0 and 1. Although there are 10 steps, there are 12 steps between tracks 1 and 2. Even if there is a difference, the position of the magnetized region in the magnetized ring 7 as the stop position information depends on the cam surface as described above. Because it is magnetized with high precision, at worst the resolution is 10 times the same as one step of a pulse motor.
The magnetic head 2 can stop within μm.

Next, the operation of cueing, that is, detecting the O track position will be explained.

In 0 track, there is another magnetized area E near the original magnetized area, and in 3 steps, another magnetized area E is located 3 steps away.
It has already been explained that X is provided as shown in FIG. 4(2).

Now, assuming that the magnetic head is stopped on the second track as an initial state, the cueing operation is started by first rotating the cam 6 in the inner circumferential direction by, for example, six steps for a six-step rotation. However, since this is performed using two-phase excitation drive, the number of rotational steps is not determined depending on the rotor position of the pulse motor. Therefore, next time, it is driven to the outer circumference by four steps.

Then, the sensing signal is determined and sent to the outer circumference one step at a time until it reaches the H level, and when it reaches the H level (when you think it has reached track number O), it is sent three more steps to the outer circumference, and the magnetized area EX is detected. Therefore, the sensing signal becomes H again.
or L level.

If it is L, there is no magnetized area EX, so the magnetized area EX, which I thought was track number 0 earlier, is track number 00.
Since it was not in the magnetized area, the operation is returned to the operation of sending it to the outer circumference in four steps unconditionally, and the above operation is repeated.

If it is H, it means that the magnetized region EX has been found, so it is determined that the outermost circumference (0 track) has been reached, and it returns to the inner circumference by three extra steps and stops. Of course, such control is performed using a control unit such as a microcomputer that receives sensing signals and controls the drive of the pulse motor.
Needless to say.

As described above, the O track position can also be determined based on the sensing signal (position information signal), and the accuracy in this case is also the same as described above.

FIG. 7 is a plan view of the cam showing the relationship between the magnetization status of the cam surface and the magnetizing ring in another embodiment of the present invention, and FIG. 8 is an explanatory diagram similar to FIG. 4 in the same other embodiment. be.

This will be explained below with reference to FIGS. 7 and 8.

First, the arrangement of the sensor (MR element) 11 is different from that shown in FIG.
The other elements ◎ act only to compensate for noise, temperature, etc., and are placed at a distance that does not make them sensitive to the magnetic field of the attachment ring 7, so that they are configured like a magnetoresistive magnetic head. ing.

This is the arrival Eft eM at fi + J 7.
This configuration is effective for sensing when the area is formed by perpendicular magnetic recording.

The main difference from the magnetization pattern in Figure 4 is 0.
The magnetization pattern is only at one track position, and the other track positions have almost the same pattern.

That is, the length of the magnetized region is longer at the O track position than at other track positions.

Therefore, the difference from the example in FIG. 4 is that during cueing operation, the sensing signal goes to H level once and
The other operations are the same in that the step (or the third step is also possible) need only be determined again.

The advantages of this example are (1) the film direction of the MR element is
Since it faces the ring 7, the ffi width can be shortened, so it is possible to perform more subdivision, that is, it can handle perpendicular magnetic recording, and (2) the magnetization pins and notches can be configured freely. Can be mentioned.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to realize highly accurate feed control of the head. It has the advantage that it can be molded and a highly accurate feeding mechanism can be made at a low cost.

Furthermore, in the head feeding mechanism according to the present invention,
The magnetization of the magnetized ring is stabilized as a whole because every other ring has a different magnetization polarity, and because there is a non-magnetized region between each magnetized region, there is no interference between the magnetized regions. Gana(,
There are practical advantages such as improving the S/N ratio of the sensing signal and preventing the ball head from becoming magnetized because the magnets are alternately magnetized with opposite polarities.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a schematic configuration of an embodiment of the present invention;
Fig. 2 is a perspective view showing the structure of only the cam in Fig. 1; Fig. 3 is a plan view of the cam showing the relationship between the cam surface and the magnetized state in the ring in Fig. 2; The diagram shows the relative positions of the track position on the disk surface, the number of steps of the pulse motor, the magnetized area of the magnetizing ring, the magnetic field direction, the sensing output (position information signal) of the sensor, etc. in the embodiment shown in FIG. 1. Fig. 5 is a characteristic diagram showing the relationship between the signal magnetic field applied to the MR element, which is a specific example of the sensor, and resistance change, Fig. 6 is an electrical wiring diagram of the MR element, and Fig. 7 is an explanatory diagram showing the relationship. FIG. 8 is a cam plan view similar to FIG. 3 in another embodiment of the present invention, and FIG. 8 is an explanatory diagram similar to FIG. 4 in another embodiment of the present invention. Explanation of symbols 1...Head carriage, 2...Magnetic head, 3.
...Disk motor, 4...Magnetic disk, 5...
Pin, 6...Cam, 7...Magnetized ring, 8...Cam surface, 9...Rotating hole, 10...Gear, 11...Sensor, 12...Hub, 13 ...Chassis, 14...
・Height pin, 15... Pressing plate, 16... Screw, 17
...Pinion gear, 18...Guide shaft, 19...
Arrow, 20...Arrow, 25...Outer peripheral wall, 26...
Pulse motor agent Patent attorney Akio Namiki No. 1 G @2 Fig. 9 Rotating hole No. 3 Fig. 5 Fig. fx8r! J@7 Figure

Claims (1)

[Claims] 1. A carriage to which a head is attached, an eccentric cam, a means for rotationally driving the cam, and a means for converting the rotational motion of the cam into a reciprocating motion of the carriage, which is attached to the carriage. A reciprocating mechanism that reciprocates (feeds) a magnetic head relative to a magnetic disk surface, and rotation stop position information of the cam corresponding to a feed stop position (position corresponding to each track) of the head on the magnetic disk surface. rotation stop position information holding means for holding the rotation stop position information on the outer periphery of the cam, and sensing means for sensing which information position held by the rotation stop position information holding means the cam is located as the cam rotates. When the sensing means senses that the cam is at the rotation stop information position (track position), the cam rotation drive means is stopped to stop the rotation of the cam, thereby moving the magnetic head to a predetermined position. a stop means for stopping the feed at a feed stop position (track position); a ring-shaped member is provided on the outer periphery of the cam as the rotation stop position information holding means; A magnetized region is formed for each (track position), and the polarity direction of the magnetic field is opposite to each other between adjacent magnetized regions, and A head feeding mechanism characterized in that the ring-shaped member is provided with a non-magnetized region that is not magnetized between the magnetic region and the magnetic region.