JPS60226071A - Magnetic reproducing device - Google Patents

Abstract

PURPOSE:To detect correctly the peak of a reproducing signal by constituting the titled device so that the output of a differentiating circuit is inputted to a comparator for outputting a complementary signal, this output is inputted to a level shifting circuit, and a pulse generating circuit for generating a pulse at the variation point of output of the comparator, the output of the pulse generating circuit is delayed, and the output of the comparator is latched. CONSTITUTION:The output signals Sa and -Sa of a differentiating circuit 4 go to inputs of a comparator 11, the outputs of the comparator 11 are complementary with each other, and its output signal (f) and the signal concerned -f go to the input of a level shifting circuit 12 and a pulse generating circuit 13. The output (h) of the level shifting circuit 12 is that produced by converting the level of the signal (f) or the signal -f to the level of a logical circuit of the post-stage, and the pulse generating circuit 13 generates a pulse at the variation point of the signal (f) and at the variation point of the signal -. The output of the pulse generating circuit 13 becomes a pulse train (i), and the pulse train (i) becomes the input of a delaying circuit 8, and it is delayed by a prescribed time pi. An output (h) of the level shifting circuit 12 is latched by the delayed pulse train (j), a signal (k) is outputted, and the signal (k) goes to the input of a one-shot multivibrator circuit 10.

Description

[Detailed description of the invention] 〔Technical field〕 The present invention relates to a magnetic reproducing device.

[Prior art]

A magnetic reproducing apparatus that uses a magnetic head to read digital data recorded on a magnetic recording medium such as a magnetic disk or magnetic tape generally has the configuration shown in FIG. The reproduced signal read by the magnetic head 1 is amplified by an amplifier 2, and then by a low-pass filter 3, excess high-frequency noise contained in the reproduced signal is removed. The output signal of the low-pass filter 3 is differentiated by a differentiating circuit 4. Next, the output of the differentiating circuit 4 becomes the input of the comparator 5. Since the output of the comparator 5 changes in accordance with the peak of the reproduced signal, the peak of the reproduced signal can be detected from the output of the comparator 5.

The output of the comparator 5 is input to a time domain filter 6, where extra peaks in the reproduced signal are removed.

FIG. 2 is a detailed block diagram of the time domain filter 6, the differentiating circuit 4, and the comparator 5 of a conventionally used magnetic reproducing device.

In FIG. 3, the output signal Sα and the prize of each block differentiating circuit 4 shown in FIG. 2 are input to a comparator 5, and are converted into a digital signal α. The digital signal α is
It becomes an input to the pulse generation circuit 7, and a pulse is generated every time the digital signal α changes. The output of the pulse generating circuit 7 is a pulse train. The pulse train is input to a delay circuit 8 and is delayed. The delay time is constant, and in FIG. 3, the delay time is set to τ. The digital signal α is latched by the delayed pulse train C, and as soon as the signal d is output, a D-type flip-flop circuit 9 can be used as an element for latching the signal d, as shown in FIG. many. Signal d is one-shot circuit 1
The input will be 0. The one-shot circuit 10 generates a pulse every time the signal d changes. The output of the one-shot circuit 10 is a pulse train. The pulse train is
The output of the comparator 5, which is so-called read data and each pulse corresponds to each peak of the reproduced signal, is single-ended, or in other words, non-complementary. Comparators of this type that are both high speed and highly accurate are expensive and of limited variety. Therefore, an inexpensive comparator - even the d1 comparator 51. Line receiver 26. LS32
etc.- are used.

However, it has the following drawbacks. Assuming that the interval between adjacent peaks of the reproduced signal is T, as in the fifth PA, the interval T1 between the change points of the output signal α of the comparator 5 is both To. However, due to the poor performance of the comparator 5, T1
and T, both of which may deviate greatly from To. When T and T deviate from To, the interval between adjacent pulses of read data T and T
4, the peak of the reproduced signal is not detected correctly because it deviates from T(+).

This causes deterioration in the performance of the magnetic reproducing device.

〔the purpose〕

The present invention is intended to solve the problem of lint. The purpose is to provide a magnetic reproducing device that correctly detects the peak of a reproduced signal.

〔overview〕

A magnetic reproducing device according to the present invention reads data by detecting the peak of a signal reproduced by a magnetic head. The output of the comparator is
The signal is input to a level shift circuit and a pulse generation circuit that generates a pulse at a change point of the output of the comparator, the output of the pulse generation circuit is delayed, and the delayed output of the pulse generation circuit is input to the comparator. It is characterized by latching the output of.

〔Example〕

Hereinafter, the present invention will be described in detail based on examples.

FIG. 4 is a block diagram of the magnetic reproducing device according to the present invention, showing the differentiating circuit 4. of FIG. Comparator 5 corresponds to time domain filter 6.

Illustrated.

The output signal Sα of the differentiating circuit 4 and the output signal 7 are input to the comparator 11. The outputs of the comparator 11 are complementary and output a signal f and a signal 7. The signal f and the signal 7 are input to the level shift circuit 12 and the pulse generation circuit 13. The output of the level shift circuit 12 is the level of the signal f1 or the signal 7 converted to the level of the subsequent logic circuit. The pulse generating circuit 13 generates pulses at the change points of the signal f and the change points of the signal 7. The output of the pulse generating circuit 13 becomes a pulse train i. The pulse train i+t becomes an input to the delay circuit 8 and is delayed.

The delay time is constant and is assumed to be τ. The output of the level shift circuit 12 is latched at the delayed pulse train node, and a signal K is output. The signal X becomes an input to the one-shot circuit 1°. The one-shot circuit 10 generates a pulse every time the signal X changes. A comparator that outputs a complementary signal whose output from the one-shot circuit 10 is a pulse train 1 is fast, highly accurate, and inexpensive. Even when combining individual parts, products with good performance can be easily produced.

Therefore, as in the explanation of FIG. 5, assuming that the intervals between adjacent peaks of the reproduction signal are all To, the interval between the changing points of the output signal I of the comparator 11 is
and To can both have values very close to T. This also applies to the signal 7. Therefore, the pulse intervals of the pulse train i, which is the output of the pulse generating circuit 15, and the pulse train j, which is the output of the delay circuit 8, each have a value extremely close to T.

It does not matter if the level shift circuit 12 has poor performance and the intervals T7 and T8 between the change points of the output signal are different.

This is due to the following reason.

For example, as shown in FIG. 5, the delay time Δτ from when the output signal f changes from a high level to a low level until the output signal of the level shift circuit 12 changes,
and after f changes from a low level to a high level, h
It is assumed that the delay time Δτ until h changes is different, and as a result, the intervals T7 and T8 between the changing points of h are different. Even in this case, if we assume that Δτ1 and Δτ are smaller than the delay time τ of the delay circuit 8, then this assumption usually holds true, and the intervals between the changing points of the signal are all equal to T. The values are extremely close. Therefore, the pulse train 11, that is, the interval '1' between adjacent pulses of the read data
Both 9 and T10 have values extremely close to To. In this way, even if the performance of the level shift circuit is poor, the peak of the reproduced signal is correctly detected in the read data.

FIG. 6 shows a specific example of the circuit shown in FIG. 4, excluding the differentiating circuit 4. In FIG. Data transfer rate is 5 Mbit/
It was designed with power supply voltages of 12 (V) and 5 (V).

As the comparator 11, IOL family 10114 is used. The level shift circuit 12 is composed of an F transistor, a resistor, and an inverter (14). The pulse generating circuit 13 is composed of a transistor P, a resistor, a capacitor, and a TTL family of four-key type IJAND.

The delay circuit 8 includes a TTL7 amily inverter (14
). The 7-lip, 70-tub circuit 9 and the one-shot circuit 10 are composed of a D-type 7-lip 70-tub circuit (874), a symbol key type ψ exclusive OR (886), and an inverter (14). In addition,
■! 1 is a DC voltage for bias.

The circuit shown in FIG. 6 is convenient because the power supply voltages are 12 (V) and 5 (V), both of which are positive voltages and do not require negative voltages.

〔effect〕

The present invention provides a magnetic reproducing device in which the output of the differentiating circuit is
A pulse generator is input to a comparator that outputs a complementary signal, and the output of the comparator is connected to a level shift circuit and a pulse generator that generates a pulse at a change point of the output of the comparator.
Since the output of the pulse generating circuit is delayed and the delayed output of the comparator is latched, it is possible to accurately detect the peak of the reproduced signal. can. As a result, the reliability of the magnetic disk device is improved.

[Brief explanation of the drawing]

FIG. 1 shows a general configuration of a magnetic reproducing apparatus that uses a magnetic head to read out digital data recorded on a magnetic recording medium. Figure 2 is a block diagram of the differential circuit and comparator 1 time domain filter of a conventional magnetic reproducing device.
3 is an illustrative waveform diagram of the function of the device shown in FIG. FIG. 4 is a block diagram of the magnetic reproducing device of the present invention. 5 is an illustrative waveform diagram of the function of the apparatus of FIG. 4; FIG. FIG. 6 is a specific example of the apparatus shown in FIG. 1...Magnetic head 2...Amplifier 3...Low pass filter 4...Differentiating circuit 5.11...Comparator 12... ... Level shift circuit 6 ... Time domain filter 7.16 ... Pulse generation circuit 8 ... Delay circuit 9 ... D-type 7 lip-flop circuit 10...One-shi blasphemy circuit and above Applicant Suwa Seikosha Co., Ltd. Agent Patent attorney Tsutomu Mogami Figure 2 Figure 3 Figure 5

Claims (1)

[Claims] In a magnetic reproducing device that reads data by detecting the peak of a signal reproduced by a magnetic head, the output of the differentiating circuit is input to a comparator that outputs a complementary signal, and the output of the comparator is level-shifted. circuit and a pulse generation circuit that generates a pulse at a change point of the output of the comparator, the output of the pulse generation circuit is delayed, and the delayed output of the pulse generation circuit is the output of the comparator. A magnetic reproducing device characterized by latching.