JPS61229272A - Vertical magnetic disk device - Google Patents

Abstract

PURPOSE:To output stably read-out data in high density recording by providing a magnetic head, a pre-amplifier, an equalizing and selecting circuit, a delay time selecting circuit, a differential amplifier selecting circuit and a differential amplifier. CONSTITUTION:After a read signal 101 is read through the magnetic head 7 and amplified by the pre-amplifier 1, it is outputted as a sub-read signal 107 in a differential amplifier adjusting circuit 5 through the delay time selecting circuit 2, and inputted to the differential amplifier 3 together with a main read signal 108. A difference between them is inputted as a differential signals 108 to a shaping circuit 4, and transmitted as a read data 109. On the other hand, a step signal 110, a direction selecting signal 111 and a track signal 112 are inputted to the equalizing and selecting circuit 6, and a delay selecting signal 113 and an amplitude selecting signal 114 are changed together with the shift of a track. Then either one of switches of a selecting circuit 2b and the differential amplifier adjusting circuit 5 is selected. With this constitution the delay time and the amplitude are optimized for each track, and the stable read-out data with less peak shifts can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates primarily to a magnetic disk device that performs perpendicular magnetic recording.

(Prior art) In the readout of perpendicular magnetic recording, the readout signal due to a solitary wave has an asymmetrical characteristic in that the fall is gradual and the rise is steep. The distortion rate of the waveform changes.

(Problem to be solved by the invention) Therefore, an equalizer is used in the reproducing circuit to correct the asymmetry, but the waveform distortion changes greatly depending on the recording density, and the attenuation amount and delay time of the equalizer are optimized. The disadvantage is that it is extremely difficult to determine a single set value.

The purpose of the present invention is to determine the optimal values of delay time and attenuation amount for each track, and to combine analog switches so that these optimal values can be selected by an external signal, and to select the optimal values according to the track number. It is an object of the present invention to provide a perpendicular magnetic recording device configured to eliminate the above-mentioned drawbacks by allowing selection and to output stable read data even in high-density recording.

(Means for Solving the Problems) A perpendicular magnetic disk drive according to the present invention includes a magnetic head, a preamplifier, an equalization selection circuit, a delay time selection circuit, a differential amplification selection circuit, and a differential amplifier. It is configured with the following.

The magnetic head is for reading information written on a magnetic disk, and the amplifier is for amplifying the output signal of the magnetic head.

The equalization selection circuit receives a step signal, which is a signal for moving the magnetic head, a direction selection signal, and an O track signal, which is a signal indicating a KO track, and outputs equalization information. .

The delay time selection circuit provides a delay time to the output signal of the preamplifier according to the output signal of the equalization selection circuit, and is switched by an analog switch.

The differential amplification selection circuit receives the output signal of the delay time selection circuit and adjusts the output amplitude according to the output signal of the equalization selection circuit.

The differential amplifier is for adding the input signal of the delay time selection circuit and the output signal of the differential amplification selection circuit.

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

FIG. 1 is a block diagram showing an embodiment of a reproducing system of a perpendicular magnetic disk device according to the present invention. In Figure 1,
1 is a preamplifier, 2 is a delay time selection circuit, 2a is a delay circuit, 2b is a selection circuit, 3 is a differential amplifier, 4 is a shaping circuit,
5 is a differential amplification adjustment circuit, 6 is an equalization selection circuit, and 1 is a magnetic head.

In FIG. 1, a read signal on a signal line 101 is read from a medium through a magnetic head 7, amplified by a preamplifier 1, and then input to a delay time selection circuit 2. The delay time selection circuit 2 consists of a delay circuit 2a and a selection circuit 2b composed of many analog switches, and sets the delay time at the time of selection according to an external signal. The output of the delay time selection circuit 2 is input to the differential amplification adjustment circuit 5. This circuit is composed of a constant current source and an analog switch, and the level of one output signal can be selected according to an external signal. The output of the differential amplification adjustment circuit 5 is sent onto the signal line 107 and becomes a sub-read signal. The sub-read signal is input to the differential amplifier 3 together with the main read signal on the signal line 105, and the difference between the read signal on the main signal edge 105 and the sub-read signal on the signal line 107 is output as a differential signal. As signal IIj! Obtained on 108.

The differential signal is input to the shaping circuit 4 and sent out on the signal line 109 as read data.

On the other hand, a step signal is input to the equalization selection circuit 6 via a signal line 110, and a direction selection signal is input to the equalization selection circuit 6 via a signal line 111. Further, an O-track signal is input to the reset terminal via a signal line 112.

It is composed of a six-digit equalization selection circuit and a decoder, and as the track moves, the delay selection signal output on the signal line 113 and the amplification selection signal output on the signal line 114 change. One of the analog switches of the selection circuit 2b and the differential amplification adjustment circuit 5 operates to select each one.

FIG. 2 is a time chart showing operating waveforms of the perpendicular magnetic disk device shown in FIG.

The operation of the above configuration will be explained with reference to the time chart shown in FIG. In Figure 2, (a) is 110
(b) is the delay signal (amplitude A) output from the delay time selection circuit 2 to the signal lines 102 to 104, respectively. (e) is the differential signal when the signal line 103 is selected. The negative phase output (amplitude B) of the amplification adjustment circuit 5, (d
) is the output of the differential amplifier 3, and (e) is the read data.

As described above, if the delay time 'pa obtained from K(IL) and (b) and the amplitude ratio (B/A) between (b) and (e) are set in advance according to the track, ( As shown in d), a waveform with less peak shift is obtained.

(Effects of the Invention) As explained above, the present invention is capable of changing the delay time and amplification degree to be optimum for each track in the readout multi-circuit enricher, and is capable of achieving stability with very little peak shift. This has the effect that read data can be obtained in a timely manner.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a reproducing system of a perpendicular magnetic disk device according to the present invention. FIG. 2 is a signal waveform diagram showing the operation of the reproduction system of the perpendicular magnetic disk device shown in FIG. 1... Preamplifier 2... Delay time selection circuit 2a... Delay circuit 2b... Selection circuit 3... Differential amplifier 4... Shaping circuit 5... Differential amplification adjustment circuit 6. ... Equalization selection circuit T ... Magnetic heads 101 to 114 ... Signal line

Claims (1)

[Claims] A magnetic head for reading information written on a magnetic disk, a preamplifier for amplifying the output signal of the magnetic head, a step signal that is a signal for moving the magnetic head, a direction selection signal, and a 0 an equalization selection circuit for inputting a 0 track signal, which is a signal indicating a track, and outputting equalization information; and a delay in the output signal of the preamplifier according to the output signal of the equalization selection circuit. a delay time selection circuit for giving time and switching by an analog switch; and a differential circuit for inputting the output signal of the delay time selection circuit and adjusting the output amplitude according to the output signal of the equalization selection circuit. 1. A perpendicular magnetic disk drive comprising: an amplification selection circuit; and a differential amplifier for adding an input signal of the delay time selection circuit and an output signal of the differential amplification selection circuit.