JPH02199604A - Write circuit for magnetic disk - Google Patents

Abstract

PURPOSE:To reduce distortion at the end of write and to decrease a readout data error due to noise by providing a circuit selecting an output of an oscillation circuit and an external write DATA signal and a circuit retarding a trailing edge of a write control signal. CONSTITUTION:The circuit is provided with a selection circuit 2 selecting an output 12 of an oscillation circuit 1 and an external write DATA signal 11 and with a delay circuit 3 retarding a trailing edge of the enable side of the write control signal 10. When the write control signal 10 goes to an H, the selection circuit 2 selects the output 12 of the oscillation circuit 1 and a write current profile generating circuit 5 generates a profile to decrease a write current of the write driver circuit 4 gradually. The profile is set so that the amplitude of the write current is sufficiently decreased within a delay time of the delay circuit 3. Thus, the distortion remaining in the magnetic head is reduced at the end of write and a DATA readout error due to noise is avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic disk device used as an auxiliary storage device in a computer system, etc., and particularly to a write circuit that is a constituent circuit thereof.

[Conventional technology]

Conventionally, the write circuit of this type of disk device has performed writing using the external write DATA signal as a magnetization pattern in accordance with an external write control signal, and then completed the write operation.

[Problem to be solved by the invention]

In the conventional write circuit described above, the end point of the external write signal is not synchronized with the external write DATA, and the current flowing through the write/read head at the end of writing is not synchronized with the external write data. There is a high probability that the #4 stream is at its maximum. Therefore, if writing ends at the maximum point in the #4 stream, magnetic distortion based on the strong magnetic field generated during writing will remain in the head even after writing is completed. Distortion is dissipated by external magnetic or mechanical stress, but there is a drawback that noise at this time causes errors in read data.

An object of the present invention is to provide a write circuit for a magnetic disk device that solves the above problems.

[Means to solve the problem]

In order to achieve the above object, a write circuit for a magnetic disk device according to the present invention includes an oscillation circuit and a selection circuit that selects an output of the oscillation circuit and a write DATA signal from the outside based on a write control signal from the outside. , a delay circuit that delays the trailing edge of the write control signal; a write driver circuit capable of externally controlling the amount of write current by inputting the output of the selection circuit and the output of the M delay circuit; The write current profile generation circuit has a signal as an input and an output connected to the write current control input of the driver circuit.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a circuit diagram showing one embodiment of the present invention.

The external write control signal 10 is the output 12 of the oscillation circuit 1.
and a write DATA signal 11 from the outside are connected to a selection input of a selection circuit 2, a delay circuit 3 that delays the trailing edge of the enable side of the write control signal 10, and a write current profile generation circuit 5. The output 13 of the selection circuit 2 is connected to the magnetization current reversal input of the write driver circuit 4, and the output 14 of the delay circuit 3 is connected to the write ON10FF control input of the driver circuit 4. Output 1 of current profile generation circuit 5
5 is connected to the write current control input of the write driver circuit 4. 6 is a head.

FIG. 2 shows an embodiment of the write current profile generation circuit when the write current control input of the write driver circuit 4 in FIG. 1 is voltage control.
51 is an inverter circuit with a push-pull type output;
2 is a diode, 53 is a resistor, and 54 is a capacitor.

The operation of the above circuit will be explained using a time chart.

FIG. 3 is a time chart for explaining the operation of the circuits shown in FIGS. 1 and 2. FIG. In FIG. 3, numerals 10 to 15 represent voltage waveforms at various parts, and numeral 16 represents a current waveform flowing through the head 6.

Now, when the write control signal 10 becomes enabled (L (IW)), the selection circuit 1i12 receives write data from the outside.
On the other hand, the output 14 of the delay circuit 3 is also enabled, and the write current profile generation circuit 5 controls the write current to the normal DATA write current value. Therefore, a current with a constant wave height that is inverted according to the write DATA All flows through the head 6, and the write control signal 1
When 0 becomes disabled (H1ah), selection circuit 2
selects the output 12 of the oscillation circuit 1, and the write current profile generation circuit 5 generates a profile that gradually reduces the write current of the write driver circuit 4. The circuit of FIG. 2 uses a time constant determined by the resistor 53 and capacitor 54, but this profile is different from the delay circuit 3.
1 of the write current within the delay time of ! Set so that @ is sufficiently small. The oscillation frequency of the oscillation circuit 1 is set to a value that can ensure a current rise at the point where the write current starts to attenuate and can generate a sufficient number of pulses within the delay time of the delay circuit 3.

Due to the operation of the circuit described above, when writing is completed, the head 6
is in a state where bulk erase has been performed, and the aforementioned magnetic distortion within the head 6 does not remain.

〔Effect of the invention〕

By configuring the magnetic disk write circuit as described above, it is possible to reduce the distortion remaining in the magnetic head at the end of writing, eliminate DATA read errors due to noise when distortion diverges, and provide a highly reliable disk device. There is.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing one embodiment of the present invention, FIG. 2 is a diagram showing an example of a write current profile generation circuit, and FIG. 3 is a circuit diagram showing an example of a write current profile generation circuit.
FIG. 2 is a time chart of the second Uf1. 1...Oscillation circuit 2...Selection circuit 3...
Delay circuit 4...Write driver circuit 5...Write current profile generation circuit 6...Head 10...Write control signal 11...Write DATA signal 12...Oscillation circuit output 13...Selection Circuit output 14...Delay 1 circuit output 15...Write current control signal 16...Write driver circuit output

Claims (1)

[Claims] (1) an oscillation circuit, a selection circuit that selects between the output of the oscillation circuit and an external write DATA signal based on an external write control signal, a delay circuit that delays the trailing edge of the write control signal, and the selection circuit a write driver circuit that can externally control the amount of write current by using the output of the output of the input circuit and the output of the delay circuit as input; 1. A write circuit for a magnetic disk device, comprising a write current profile generation circuit connected thereto.