JPS6369075A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To improve the recording density of a magnetic disk device while decreasing the danger of head crash by impressing a voltage between a magnetic head and a disk plate only at the time of writing and reading operation. CONSTITUTION:A controller 12 instructs a head address changing-over device 10 and a direct current voltage generating device 11 to impress a direct current voltage to a magnetic head 2 only at the time of re-trying after a reading error occurs. Thus, the flying height of the head 2 comes to be lower by impressing the voltage only for the time to execute the reading writing operation, and an S/N is secured. Consequently, the chance to generate the contact with the magnetic head 2 and a magnetic disk plate 1 is small, the generating ratio of head crash is decreased and recording density can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic disk device that is an external storage device for a computer.

[Conventional technology]

Conventionally, in this type of magnetic disk drive, the distance between the magnetic head and the magnetic disk plate, that is, the flying height of the magnetic head slider, depends on the geometric shape of the slider, the load pressing the slider, and the relative speed between the magnetic head and the magnetic disk. It is determined at the time of design and cannot be changed at the moment of device lead error. Therefore, if a read error occurs in the magnetic disk device,
Perform a read retry as is. ①Correct the erroneous data using an error correction code (ECC). In addition, data is secured as much as possible using techniques such as (2) read retry, which involves offset of the read window or offset of the radial position of the magnetic head.

[Problem that the invention seeks to solve]

When correcting read errors in the conventional magnetic disk drive described above, a 0-term read retry has little effect on correction. Regarding item (2), additional circuits and software are required to process ECC, which is expensive. Regarding the 0 term, additional circuitry is needed to perform a punch track, and in particular, for read retry, which includes an offset in the radial position of the magnetic head, it is necessary to use servo loop technology for accurate positioning, and software control is required. This is an expensive device. In addition, neither the ECC processing method (section (2)) nor the offset method (section (2)) have a sufficient effect of correcting read errors, resulting in significant control when increasing the density of magnetic disk drives. On the other hand, in order to increase the recording density and ensure the S/N ratio of the read signal in the conventional magnetic disk device described above, it is necessary to reduce the flying height of the magnetic head slider. On the other hand, when the flying height is reduced, contact between the magnetic head slider and the magnetic disk plate becomes more likely to occur due to protrusions on the surface of the magnetic disk plate, dust I floating inside the magnetic disk device, etc. This has the disadvantage that head crashes are more likely to occur, impairing the reliability of the magnetic disk device.

[Means for solving problems]

The present invention provides an electrically conductive magnetic head slider, an insulator that interrupts electrical conduction between the magnetic head slider and the magnetic disk plate, a DC voltage generator that applies a DC voltage between the magnetic head slider and the magnetic disk plate, and a DC voltage generator that applies a DC voltage between the magnetic head slider and the magnetic disk plate. It has a controller that instructs the application of DC voltage only during a retry operation. In this configuration, a DC voltage is applied between the magnetic rad slider and the magnetic disk plate in order to lower the flying height during a retry operation after a read error occurs than the normal flying height.

The present invention relates to a conductive magnetic head slider, an insulator that interrupts conduction between the magnetic head slider and the magnetic disk plate, a DC voltage generator that applies a DC voltage between the magnetic head slider and the magnetic disk plate, and a DC voltage generator that applies a DC voltage during writing or reading. It has a controller that instructs the application of DC voltage only during both operations. In this configuration, a DC voltage is applied between the magnetic head slider and the magnetic disk plate in order to make the flying height during write/read operations lower than the flying height during non-write/read operations.

〔Example〕

Next, the present invention will be explained with reference to the drawings. FIG. 1 is a block diagram of an embodiment of the present invention.

A magnetic disk plate 1 is arranged facing a magnetic head 2,
The distance between the slider 2-1 of the magnetic head 2 and the magnetic disk plate 1, that is, the flying height, is determined by the shape of the slider, the load of the slider presser springs 2 and 3, and the relative speed of the magnetic disk plate with respect to the slider. The magnetic disk plate 1 is fixed to a spindle hub 3, and the spindle hub 3 is mounted on a bearing 7. It is rotationally driven by a brushless motor 6. The bearing 7 is held on the base plate 4. The spindle hub 7 is electrically connected to the contact pad 5 at its axial end. The magnetic head 2 is held by a carriage 8 and positioned at an arbitrary radial position on the magnetic disk plate.

The magnetic head slider 2-1 is held and insulated by an insulator holder 9 at the junction of the carriage 8 and the presser spring 2-3.

The magnetic head 2 is connected to the contact pad 5 through a head address switch 10 and a DC voltage generator 11. The controller 12 instructs the head address switch 10 and the DC voltage generator 11 to apply a DC voltage to the magnetic head only during a dry drive operation after a read error occurs.

FIG. 2 shows the relationship between the flying height of the magnetic head slider and the applied voltage. The flying height during normal write/read on the innermost circumference is set to 0.
．． Set to 3 μm. Applied voltage is 30V, 60V, 90V
The flying height for V is 0.26 μm and 0.19 μm, respectively.
m, 0.14 μm. The flying height when a voltage is applied becomes the flying height during a retrite operation. When the recording density at the innermost circumference (36 radius) is 18000 BP I, the maximum and minimum writing frequencies are 3jMHz and 1, respectively.
．． It becomes 25MHz. 34MHz output voltage and 1.25
The ratio of MHz output voltages is defined as resolution.

FIG. 3 shows the relationship between the read output voltage at the highest write frequency and the applied voltage at the resolution. By setting the applied voltage to 90 volts, the output voltage increased by 25% and the resolution increased by 9%.

In addition, only when a read retry operation is to be performed, a voltage is applied only during the time when the read retry operation is performed, and the floating
By simply reducing the amount, the chances of contact between the magnetic head and the magnetic disk plate can be significantly reduced, and the incidence of head crashes can be significantly reduced.

FIG. 4 is a block diagram of another embodiment of the present invention.

A magnetic disk plate 1 is arranged facing a magnetic head 2,
The distance between the slider 2-1 of the magnetic head 2 and the magnetic disk plate 1, that is, the flying height, is determined by the shape of the slider 1&, the load of the slider presser spring 2-3, and the relative speed of the magnetic disk plate with respect to the slider. The magnetic disk plate l is fixed to the spindle hub 3, and the spindle hub 3
is bearing 7. It is rotationally driven by a brushless motor 6.

The bearing 7 is held on the base plate 4. The spindle hub is electrically connected at its axial end by contact pads 5. The magnetic head 2 is held by a carriage 8 and positioned at an arbitrary radial position on the magnetic disk plate.

The magnetic head slider 2-1 is held and insulated by an insulator holder 9 at the junction of the carriage 8 and the presser spring 2-3. The magnetic head 2 is a head address switcher 1
0, connected to the contact pad 5 through a DC voltage generator 11. The controller 12A instructs the head address switch 10 and the DC voltage generator 11 to apply a DC voltage to the corresponding magnetic head only when writing and reading signals.

FIG. 5 shows the relationship between the read output voltage at the highest write frequency and the applied voltage at the resolution in this example. Magnetization reversal density I) which gives an output voltage of 50% of the output voltage of a high solitary wave
So is also shown in the same figure. By setting the applied voltage to 90 volts, the output voltage increases by about 1.5 times, and the resolution increases from 70% to 82%.

Again,. is 20500 FRP I to 26000
It rose to FR and PI.

In addition, since voltage is only applied to the head that performs write/read operations and the flying height is lowered only during the write/read time, the chances of contact between the magnetic head and the magnetic disk plate are significantly reduced, and head crashes are avoided. The incidence can now be significantly reduced.

〔Effect of the invention〕

As explained above, the present invention reduces the risk of head crash by applying DC voltage between the magnetic head and the disk plate only during write/read operations.
This has the effect of increasing the recording density of magnetic disc and tape devices.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention, FIG. 2 is a characteristic diagram showing the relationship between the applied voltage and the flying height in FIG. 1, and FIG. 3 is the applied voltage and output voltage in FIG. A characteristic diagram showing the relationship between read wind margin, FIG. 4 is a configuration diagram of an embodiment of the pond of the present invention, and FIG. 5 is a characteristic diagram showing the relationship between applied voltage, output voltage 1 resolution, and magnetization reversal density in FIG. 4. It is. 1... Magnetic disk plate, 2... Magnetic head, 2-1
...Magnetic head slider, 2-3...Magnetic head presser spring, 4...Base plate, 5...Contact pad, 6...Brushless motor, 7...Bearing, 8...
- Carriage, 9... Insulator holder, 10... Head address switch, 11... DC voltage generator, 12.
12A...Controller. O30ρ 2θ Wholesale Ka Q#7i (Bow 1bh) Fig. 2 0 wo θ Otsu 0 De 0 Application # catty (Board knowledge 3 section

Claims (2)

[Claims] (1) A conductive magnetic head slider, an insulator that breaks conduction between the magnetic head slider and the magnetic disk plate, a DC voltage generator that applies DC voltage between the magnetic head slider and the magnetic disk plate, and after a read error. 1. A magnetic disk drive comprising: a controller that instructs application of a DC voltage only during a retry operation. (2) A conductive magnetic head slider, an insulator that breaks conduction between the magnetic head slider and the magnetic disk plate, a DC voltage generator that applies a DC voltage between the magnetic head slider and the magnetic disk plate, and writing or reading. 1. A magnetic disk device comprising a controller that instructs application of a DC voltage only when one or both operations are performed.