JPS63281201A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To improve a reliability in a high recording density by providing a driving mechanism to move a magnetic head to arrange two gaps of a gap for recording and a gap for reproducing in parallel in the rotation direction of a recording medium only by the distance between two gaps. CONSTITUTION:A driving mechanism to move a magnetic head to arrange mutually in parallel two gaps of a gap 21 for recording and a gap 22 for reproducing at the interval of a physical distance in the rotation direction of a recording medium only by a distance Ld between two gaps 21 and 22 is provided. The recording of information to the recording medium is executed by the gap 21 for recording and the reproducing is executed by the gap 22 for reproducing. Thus, since the gap of a magnetic head is separated to the gap for recording and the gap for reproducing, the dimension, etc., of respective gaps 21 and 22 can be optimumly designed independently to match to respective conditions of the recording and reproducing and the mechanism to move the magnetic head is provided, and therefore, the gaps 21 and 22 come to the same position at the time of the recording and at the time of the reproducing viewed from the recording medium. Thus, in a high recording density, a stable and highly reliable recording and reproducing can be executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic disk device that writes and reads information to and from a rotating magnetic recording medium.

In particular, the present invention relates to a magnetic disk device that can realize recording and reproduction with high reliability even at high recording densities.

[Conventional technology]

In a conventional magnetic disk device that drives a flexible disk as a magnetic recording medium, signals are recorded and reproduced using a single gap provided in a magnetic head.

During recording, the gap in the magnetic head must have the ability to generate a sufficient recording magnetic field to counter the coercive force of the magnetic layer of the recording medium. It is necessary to have the ability to apply a magnetic field two to three times the coercive force of the layer to achieve complete saturation recording. In order to generate a strong magnetic field from a gear sop, the gap length must be wide, and generally needs to be equal to or greater than the thickness of the medium magnetic layer.

On the other hand, during playback, if the gap length is an integer multiple of the recorded signal wavelength, the playback output will be zero due to gap length loss, so considering the resolution of the playback output, it is better to keep the gap length as narrow as possible. It is necessary to narrow the wavelength to about 2 times the recording signal wavelength.

Therefore, in conventional magnetic disk drives, it is necessary to set the gap length of the magnetic head within a range that satisfies the conditions during recording and reproduction.

[Problem that the invention seeks to solve]

By the way, with the demand for smaller size and larger capacity of magnetic disk devices, there is a tendency for recording density to become higher and higher. In order to achieve high recording density, recording media must:
It is necessary to increase the coercive force and reduce the thickness of the media magnetic layer, but in the case of coated media, it is not possible to reduce the thickness of the magnetic media below a certain level when considering coating unevenness and the filling rate of the magnetic material. Currently, the limit is about 1 micron.

Therefore, in a conventional magnetic disk device in which recording and reproduction are performed using a single gear, the gap length cannot be made narrower depending on the recording conditions, and therefore there is a limit to the recording density. Conversely, if the gap length is narrowed in accordance with the recording density, it will not be possible to completely saturate the magnetic layer of the recording medium, and if signals are overwritten, the previously written signals will be completely erased. This causes problems with reliability, such as making it impossible to ensure compatibility of information or causing reading errors.

SUMMARY OF THE INVENTION In view of these problems, it is an object of the present invention to provide a magnetic disk device that enables stable and reliable recording and reproduction even at high recording densities.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention provides a magnetic head in which two gaps, a recording gap and a reproduction gap, are arranged parallel to each other with a physical distance between them; The recording medium is configured to include a drive mechanism that moves the recording medium in the rotational direction by the distance between the gaps.

[Effect]

By separating the magnetic gap into a recording gap and a reproduction gap in this way, it is possible to satisfy both the conditions required for recording and the conditions required for reproduction even at high recording densities. Moreover, when looking at the magnetic head from the recording medium, the recording gap during recording and the reproducing gap during reproduction can be located at the same position, so there is no azimuth loss during reproduction and good recording and reproduction can be achieved. Become.

〔Example〕

Embodiments of the magnetic disk device of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a head carriage used in a magnetic disk device according to the present invention and a part of a case to which the head carriage is attached.

The head cab 1 is provided with a hole 3 and a groove 4 into which a support rod 2.21 is inserted. Furthermore, a magnetic head 5.5' is mounted for recording and reproducing information on both sides of the disk. Both ends of the support rod 2' inserted into the groove 4 are fixed to the protrusion 6 of the box, and the support rod 2' inserted into the hole 3 has a longitudinal direction at both ends. A laminated piezoelectric element 7.7" that expands and contracts in the right angle direction is attached to a fixing jig 8.8'
Furthermore, the end of the piezoelectric element 7.7' opposite to the fixing jig 8.8' is attached to the protrusion 9.91 of the box.
is fixed.

With such a configuration, the head carriage 1 can freely move in the longitudinal direction of the support rod 2.2 degrees, that is, in the normal direction of the concentric tracks of the recording medium, but can move vertically or horizontally. Therefore, if the piezoelectric element 7.7" extends by applying a voltage, the movement in the direction of the support rod 2.2" is restricted.
Since the head carriage 1 moves in a direction perpendicular to its longitudinal direction, the head carriage 1 moves in the normal direction of the concentric tracks, that is, in the direction of medium rotation (direction of arrow A).

Although not shown in the figure, in order to move the head carriage 1 to each track, a stepping motor is connected to the carriage 1 via a steel band, a steel belt, or a single screw, as in the prior art.

FIG. 2 is a diagram showing the core portion of the magnetic head 5 (5') used in the magnetic disk device of the present invention, in which a recording gap 21 and a reproducing gap 22 are arranged parallel to each other with a physical distance Ld between them. has been done. A recording magnetic circuit is formed by the L core 23, i core 24, and back core 25 that form the recording gap 21, and a recording coil 28 is wound around a part of the magnetic circuit. Similarly, a magnetic circuit for reproduction is formed by the L core 26, I core 27, and back core 25 that form the reproduction gap 22, and a reproduction coil 29 is wound around a part of the magnetic circuit.

The recording gap length is set to be equal to or slightly wider than the thickness of the magnetic medium layer in order to completely saturate the medium magnetic layer. Further, the reproduction gap length is set to approximately A of the recording signal wavelength in order to prevent a decrease in reproduction voltage due to gap length loss.

The gap distance Ld is set to a thickness such that (1) the core 24.27 does not cause magnetic saturation, and is usually set to 0.2 mm or more.

In addition, the recording gap width Lw and the reproduction gap width Lr are set in consideration of the positioning error of the magnetic head in the magnetic disk device and the expansion and contraction of the medium due to changes in temperature and humidity. Lw>Lr is set so that there is no unerased signal or mixing of signals from adjacent tracks.

Such a core structure is suitable for bulk magnetic heads used in conventional flexible magnetic disk drives.
Since the structure is basically the same as that of the core that forms the erase gear 7, in which the central part is not hollowed out, manufacturing is easy.

The magnetic head configured as described above is configured such that the width direction of the recording gap 21 coincides with the normal direction of the recording medium.
It is mounted on the head carriage 1 shown in FIG. 1 above.

FIG. 3 is a diagram showing a circuit for driving the piezoelectric element 7.7° shown in FIG. 1. Two piezoelectric elements 7.7° are connected in parallel to each other, and these piezoelectric elements 7.7"
A DC current aI31, a switching transistor 32, and a variable resistor 33 are connected in series.

On/off of the voltage application to the piezoelectric element 7.7° is controlled by applying a write gate signal to the base terminal 34 of the switching transistor 32.

The value of the voltage applied to the piezoelectric element 7.7'' is determined by changing the value of the variable resistor 33 while reproducing a medium on which a signal has been recorded in the recording gap 21 during assembly of the magnetic disk device, using the reproduction gap 22. Set the resistance value to maximize the playback output.

The switching transistor 32 described above may be replaced with another switching element such as a relay.

In this figure, two piezoelectric elements 7.7' are connected in parallel, but an individual drive circuit is provided for each piezoelectric element 7.7°, and these piezoelectric elements 7.7° are driven independently. By doing so, more precise control can be performed, including variations in each piezoelectric element.

With the head carriage, magnetic head, and drive circuit configured as described above, the write gate signal is turned on during signal recording, the switching transistor 32 does not operate, and no voltage is applied to the piezoelectric element 7.71, so that the recording gap is 21 coincides with the normal direction of the rotation of the medium. During signal reproduction, the write gate signal is turned off, the switching transistor 32 operates, and the piezoelectric element 7.7'
A voltage is applied to the piezoelectric element 7.7'', which extends in the length direction, thereby causing the head carriage 1 to also move in the direction of rotation of the recording medium (in the direction of arrow A).

At this time, if the head carriage 1 is set to move by the distance Ld between the recording gap 21 and the reproduction gap 22 by adjusting the variable resistor 33 of the piezoelectric element drive circuit when assembling the magnetic disk device, the reproduction gap 22 can be moved by the distance Ld between the recording gap 21 and the reproduction gap 22. As a result, the signal recorded in the recording gap 21 can be reproduced in the reproduction gap 22 without any azimuth loss.

Note that in the above configuration, the cabling 1 is moved by applying a voltage to the piezoelectric elements 7 and 7' during reproduction, but
Conversely, it is also possible to adopt a configuration in which the cabling 1 is moved by applying a voltage to the piezoelectric element 7.7'' during recording.

FIG. 4 is a diagram showing another embodiment of a head carriage and a mounting portion used in a magnetic disk device.

Generally, a stacked piezoelectric element generates a large stress but a small amount of displacement. Therefore, here, the amount of displacement of the piezoelectric element is expanded and transmitted to the support rod 2 using the lever principle.

Both ends of the support rod 2 inserted into the hole 3 of the carriage 1 are
T-shaped fixture 10.10° is engaged with one arm 11.111. The tip 12.121 of the leg of this T-shaped fixing jig 10.10' is pivotally supported by the protrusion 9.9° of the box, and the arm 1 on the opposite side to the side to which the support rod 2 is attached
A laminated piezoelectric element 7.7'' is inserted at 3.13° so as to be sandwiched between the T-shaped fixture 10, 10'' and the protrusion 9.9' of the box. With this configuration, if the length of the arm of the T-shaped fixture 10.10° is adjusted appropriately,
A small displacement of the piezoelectric element 7,7' allows the support rod 2 of the carriage to be moved significantly in the direction of the arrow B.

In FIG. 4, the direction in which the support rod 2 moves due to the expansion and contraction of the piezoelectric element is opposite to that in FIG. 1, but the T-shaped fixing jig 10
By changing the mounting method, it is easy to make the direction the same as in FIG. 1.

FIG. 5 is a diagram showing another embodiment of a head carriage used in a magnetic disk device. Carriage 1 support rod 2
．． A notch 1 is formed between the part 14 provided with the 2" insertion hole 3 and the groove 4 and the part 15 on which the magnetic head 5.5' is mounted.
6, and a laminated piezoelectric element 7'' is inserted into this part, and the support rods 2.2g are both attached to protrusions 6.9.9 of the box.
It is fixed at 9'. When a voltage is applied to the piezoelectric element 7'', the piezoelectric element 7'' stretches, and the head mounting portion 15 of the carriage moves around the carriage coupling portion 17 in a direction perpendicular to the direction in which the piezoelectric element 7 extends, that is, the recording medium. move in the direction of rotation.

With this configuration, only one piezoelectric element 7'' is required,
Also, the distance from the carriage coupling part 17 to the piezoelectric element 7'' is 5.5 degrees from the carriage coupling part 17 to the magnetic head.
If the distance from Because of the rotational motion, the magnetic field 5
．． An azimuth loss occurs by the distance Ld between the recording gap 21 and the reproduction gap 22 of 5 degrees, but this can also be reduced by adjusting the adjustment error if the distance between the carriage coupling part 17 and the magnetic head 5 is made sufficiently long with respect to the gap distance Ld. It can be kept to a certain extent.

〔Effect of the invention〕

As is clear from the above explanation, in the present invention, since the caps of the magnetic head are separated for recording and reproduction, the dimensions of each gap can be optimally designed independently according to each recording and reproduction condition. Moreover, since a mechanism for moving the magnetic head is provided, each gap can be placed at the same position during recording and reproduction when viewed from the recording medium, and the simple configuration allows for stable and high performance even at high recording densities. You can record and play back with confidence. Furthermore, since the laminated piezoelectric element generates a large stress, the rigidity of the carriage or the carriage attachment part can be made equal to that of the conventional one, and highly accurate positioning can be achieved. Furthermore, by appropriately adjusting the voltage applied to the piezoelectric element using an alignment disk when assembling and adjusting the magnetic disk device, azimuth adjustment, burst signal adjustment, etc. can be easily performed. In addition, the magnetic head has a simple structure, and since it is sufficient to consider recording conditions and reproduction conditions independently, it is easier to design and manufacture than conventional magnetic heads.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of a head carriage and a mounting part in a magnetic disk device of the present invention, FIG. 2 is a perspective view of an embodiment of a core of a magnetic head used in the magnetic disk device, and FIG. 1 is a circuit diagram of a drive circuit for a laminated piezoelectric element in the carriage mounting portion of FIG. 1, and FIGS. 4 and 5 are perspective views showing other embodiments of the head carriage and mounting portion in the same magnetic disk device. 1... Head carriage, 2.2'... Carriage support rod, 3... Hole, 4... Groove, 5.5°... Magnetic heel, 6... Projection of box , 7.7゛, 7''・
...Laminated piezoelectric element, 8...Fixing jig, 9.9'...
・Protrusion of the box, 1O110"...T-shaped fixing jig,
11.111...Arm, 12.12"...Tip, 13
．． 13g... Arm, 14... Part with holes and grooves, 15
... Magnetic head mounting portion, 16... Notch, 17... Carriage coupling portion, 21... Recording gap, 22... Playback gap, 23... L core,
24... ■Core, 25... Back core, 26...
L core, 27... ■core, 28.29... coil,
31... DC power supply, 32... Switching transistor, 33... Variable resistor. Agent Patent Attorney Tsuneaki Nagao Figure 4

Claims (3)

[Claims] (1) In a magnetic disk device that writes information to and reads information from a rotating magnetic recording medium, a magnetic head is used in which two gaps, a recording gap and a reproduction gap, are arranged parallel to each other with a physical distance between them. and a drive mechanism for moving the magnetic head in the rotational direction of the recording medium by the distance between the two gaps, recording information on the recording medium using the recording gap and reproducing information using the reproducing gap. A magnetic disk device that operates using gaps. (2) The magnetic disk device according to claim 1, wherein a laminated piezoelectric element is used in the drive mechanism. (3) The moving distance of the magnetic head in the medium rotation direction is made to match the gap interval of the magnetic head by adjusting the voltage applied to the laminated piezoelectric element. The magnetic disk device according to item 2.