JPH0287306A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To prevent the decrease in the peak value of the highest frequency by preventing the interference of a low pass filter by a buffer amplifier, using a lead filter so as to increase the highest frequency component of a readout signal and adjusting the relation of the between a gate channel and a time channel by a delay line. CONSTITUTION:An output signal of an input amplifier 1 passes through a low pass filter 2 and inputted to a time channel and a gate channel respectively. The gate channel is provided with a buffer amplifier 10 and a lead filter 11 and an output signal of the input amplifier 1 is inputted to the buffer amplifier 10. The output of the buffer amplifier 10 is inputted to the lead filter 11 and since the lead filter has a bypass characteristic or a band pass characteristic, the maximum frequency component of the output signal from the buffer amplifier 10 is increased. Thus, a waveform shown in figure is obtained from the output signal of the buffer amplifier 10 at the inner circumferential side with a high recording density by using the lead filter 11. Thus, the peak of the highest frequency is averaged.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a magnetic disk device.

(Prior Art) Fig. 4 is a block diagram showing the configuration of a conventional magnetic disk device, in which 1 is an input amplifier, 2 is a low-pass filter, 3 is a full-wave rectifier circuit, 4 is an AGC circuit, 5 is a differentiator, 6 is a is a bidirectional one-shot, 7 is a differential comparator, 8 is a D flip-flop, and 9 is a bidirectional one-shot.

In conventional magnetic disk drives, as shown in FIG. 4, the original waveform slicing method is widely used as a peak detection method for output signals 101 and 102 of read/write amplifiers that match magnetic heads.

In FIG. 4, the read/write amplifier output signal 10
1 and 102 are AC-coupled to the input amplifier 1, and the output signal of the input amplifier 1 passes through the low-pass filter 2, is rectified by the full-wave rectifier circuit 3, is compared with the slice level signal 104 by the AGC circuit 4, and is connected to the input amplifier 1. Adjust and set the gain of 1. Further, the output signal of the input amplifier 1 that has passed through the low-pass filter 2 is input to a time channel and a gate channel. The time channel is composed of a differentiator 5 and a bidirectional one-shot 6, detects the peak of the output signal of the input amplifier 1, and generates a time pulse 107.

The gate channel is composed of a differential comparator 7 having a set hysteresis signal 105, a D flip-flop 8, and a bidirectional one-shot 9, and uses a time pulse 107 to generate read data 106.

Here, when the input waveform of input amplifier 1 reaches the lowest frequency and then the highest frequency, if the difference in magnetic flux reversal between the inner and outer tracks is large, the lowest frequency on the inner track becomes a sign as shown in Figure 5 (B). An output waveform that is close to a wave and has a small peak value at the highest frequency can be obtained.

Therefore, depending on the setting of the slice level, the peak value on the inner circumference side may fall below the slice level.

In addition, when operating with a waveform such as the one on the inner circumferential side of FIG. 5(B), when the input waveform as shown in FIG. It has the disadvantage of distorting the output waveform.

In addition, in FIG. 4, 103 shows a read/write switching signal, and FIG. 5(A) shows an output waveform on the outer circumferential side.

(Problems to be Solved by the Invention) It is an object of the present invention to avoid the above-mentioned drawbacks caused by the magnitude of magnetic flux reversal in the output waveform of a read/write amplifier and to match the magnetic head. An object of the present invention is to provide a magnetic disk device that overcomes the magnitude of magnetic flux reversal caused by differences in magnetic flux and enables highly stable and highly dependent peak detection.

[Structure of the Invention] (Means for Solving the Problems) A magnetic disk drive according to the present invention includes an input amplifier that inputs an output signal of a read/write amplifier, a low-pass filter that inputs an output signal of this input amplifier, and a low-pass filter that inputs an output signal of this input amplifier. A time channel that is connected to the output side of the low-pass filter and generates a time pulse by detecting the peak of the output signal of the input amplifier; and a time channel that is connected to the output side of the low-pass filter and generates read data by inputting the time pulse. In a magnetic disk drive, the low-pass filter is connected between the low-pass filter and the gate channel, and the low-pass filter is connected between the low-pass filter and the gate channel. The present invention is characterized in that it comprises a buffer amplifier that prevents interference of the read signal, a read filter that boosts the highest frequency component of the read signal, and a delay line connected between the time channel and the gate channel.

(Function) According to the present invention, in a magnetic disk drive that detects the peak of the output signal of a read/write amplifier matched to a magnetic head, the buffer amplifier prevents interference of the low-pass filter, and the read filter prevents interference of the read signal. By increasing the high frequency components and adjusting the time relationship between the gate channel and time channel using a delay line, the conventional problem caused by the magnitude of magnetic flux reversal in the output waveform of the read/write amplifier can be solved. can.

(Embodiment) Fig. 1 is a block diagram showing the configuration of an embodiment of the present invention, in which 1 is an input amplifier, 2 is a low-pass filter, 3 is a full-wave rectifier circuit, 4 is an AG circuit, and 5 is a differentiator. , 6 is a bidirectional one-shot, 7 is a differential comparator, 8 is a D flip-flop, 9 is a bidirectional one-shot, 10 is a buffer amplifier, 11 is a lead filter, and 12 is a delay line.

Further, 101 to 102 are read/write amplifier output signals, 103 is a read/write switching signal, 104 is a slice level signal, 105 is a set hysteresis signal,
106 indicates read data, and 107 indicates a time pulse.

In FIG. 1, parts that are the same as those shown in FIG. 4 are designated by the same reference numerals, and their operations are the same as those described with respect to FIG. Therefore, regarding the operation of the embodiment of the present invention shown in FIG. 1, the portions that are different from the operation of the conventional example shown in FIG. 4 will be explained.

In FIG. 1, the output signal of an input amplifier 1 passes through a low-pass filter 2 and is input to a time channel and a gate channel, respectively. Unlike the conventional example shown in FIG. 4, the gate channel includes a buffer amplifier 10 and a lead filter 11. The output signal of input amplifier 1 is input to buffer amplifier 10. The buffer amplifier 10 is for preventing the influence of the low-pass filter 2 from the lead filter 11. The output of the buffer amplifier 10 is input to a read filter 11. The lead filter 11 has bypass characteristics or bandpass characteristics, and lifts the highest frequency component of the output signal of the buffer amplifier 10. As a result, the output signal of the buffer amplifier 10 on the inner circumferential side where the recording density is high as shown in FIG. 2 has a waveform as shown in FIG. 3 by the read filter 11. Therefore, the peak values are averaged.

In addition, the time channel has one delay line in addition to the conventional circuit.
2 is added, and this delay line 12 adjusts the time relationship between the buffer amplifier 10 and read filter 11 added to the gate channel and the time channel.

[Effect of the invention] According to the present invention, the following effects can be achieved.

(1) Even on the inner circumferential side where the recording density is high and the resolution is lower, the setting margin for the slice level becomes wider, and the margin for off-track of the magnetic head and the margin for S/N become larger.

(2) Since the level fluctuation of the read signal is reduced, A
The disadvantage of waveform distortion in the response of the GC circuit is improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIGS. 2 and 3 are output signal waveform diagrams for explaining the operation of the embodiment of the present invention, and FIG. 4 is a conventional A block diagram showing the configuration of an example, and FIGS. 5 and 6 are waveform diagrams for explaining the operation of the conventional example, respectively. 10... Buffer amplifier, 11... Lead filter, ]2... Delay line. Applicant's agent Patent attorney Suzue Takehiko0ku

Claims (1)

[Claims] An input amplifier that inputs the output signal of the read/write amplifier, a low-pass filter that inputs the output signal of this input amplifier, and a low-pass filter connected to the output side of this low-pass filter that detects the peak of the output signal of the input amplifier and calculates the time. It is equipped with a time channel that generates a pulse, and a gate channel that is connected to the output side of the low-pass filter and that inputs the time pulse and generates read data. In a magnetic disk drive that detects a peak, the buffer amplifier is connected between the low-pass filter and the gate channel to prevent interference with the low-pass filter, and the read filter increases the highest frequency component of a read signal; and the time channel. and a delay line connected between the gate channel and the gate channel.