JPH0233705A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To read signal on a recording medium with a thin film magneto- resistance effect-type head by converting an analog input signal to a pulse signal, for which frequency modulation is executed, in a frequency converting part and recording the signal through an induction type thin film magnetic head on the recording medium in a pulse train generating part. CONSTITUTION:An analog signal A is inputted to an LPF4 of a magnetic recording and reproducing device and an output signal is outputted through an amplifier 5 for level control as a signal B. The signal B is inputted to a voltage controlled oscillator VCO6 as a control voltage and the frequency of the output signal is made a signal which is proportional to the voltage level of the input signal B. The output signal of this VCO6 is inputted to a counter 7 and a counter 8, to which an output signal C is inputted, and inputted to monostable multivibrator 9 and 10 as the clock signal of the monostable multivibrator 9 and 10. Then, data signals D and E are outputted from the counter 8, to which the signal C is inputted. After that, the data signal D is inputted to the monostable multivibrator 9 and the data signal E is inputted to the monostable multivibrator 10.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Field of Application> The present invention relates to a magnetic recording/reproducing apparatus that can separately record/reproduce information on a plurality of tracks on a magnetic tape.

<Prior Art> Conventionally, a wire-wound head is often used as a reproducing head of a magnetic recording/reproducing device. However, such a wire-wound head requires a wire to be wound around the core, making it large and making it impossible to reduce the distance between the heads and other heads. - Not suitable for racking.On the other hand, thin-film magnetoresistive heads that utilize the magnetoresistive effect of ferromagnetic alloy thin films (
The MHI-I (hereinafter referred to as MHI-I) is suitable for increasing the number of tracks compared to wire-wound heads because it is easy to integrate and has high productivity.

<Problems to be Solved by the Invention> However, the characteristics of the MRI-i are different from those of a wire-wound head, and the relationship between magnetic field strength and output is not linear.

Moreover, it is not possible to raise the reproduction frequency too high. For this reason, AC bias recording method and pulse width modulation (pulse width modulation)
Hereinafter, when an analog signal recorded by I) WM modulation and 5) method is reproduced, the output signal is
There is a problem in that it becomes distorted as shown by ρ in the figure.

That is, FIG. 3 is a block diagram of a conventional magnetic recording/reproducing apparatus that records signals on a magnetic tape using PWM modulation signals. During recording, this magnetic recording/reproducing device:
The input analog voice “a” is passed through the low-pass filter 24
The signal passes through the amplifier 25 and is input to the sawtooth wave generator 29. Then, this sawtooth wave generator 29 becomes
PW is triggered by a signal input from the oscillator 26 via the counter 27 and the monostable multibubber 28.
An M-modulated signal "d" is output. This PWM modulation signal "d" is input to the monostable multivibrator 30, and based on the output signal of this monostable multivibrator 30 and the signal from the monostable multivibrator 28, a current signal is sent from the pulse train type recording amplifier 31. “h”
is output. Based on this signal "l", a PWM signal is recorded on the magnetic tape 21 by the interlayer thin film magnetic head 22.

At the time of playback, the data from the magnetic tape 21 is recorded.
The signal "1" read out by the I23 and amplified by the reproducing amplifier 32 is input to the low-pass filter 33, and a demodulated signal "a" of the input signal "a" is output. At this time, distortion occurs in the signal "a" because the width of the level "H" of the signal "1" is different ("17°" is a demodulated signal without distortion).

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic recording/reproducing apparatus which can easily implement multi-track MRI-1 and which does not cause distortion in demodulated signals.

<Means for Solving the Problems> In order to achieve the above object, the present invention includes an Indakun Yong type thin film magnetic head for recording, an MRH for reproduction, and a pulse train generation section, and performs recording by a pulse train method. In a magnetic recording/reproducing device that records a signal on a medium and reproduces the signal recorded on the recording medium, an analog input signal is converted into a frequency-modulated pulse signal to generate a pulse train. The present invention is characterized in that it includes a frequency modulation section that outputs an output to the recording medium, and a frequency demodulation section that demodulates the frequency of the signal read from the recording medium by the thin film magnetoresistive head.

<Operation> When an analog signal is input, the analog input signal is converted into a frequency-modulated pulse signal by the frequency modulation section and input to the pulse tray generation section. Then, the pulse train generation section records a signal on the recording medium via the induction type thin film magnetic head by a pulse train method based on the input frequency modulated pulse signal.

On the other hand, the signal recorded on the recording medium is read by MRH 3, demodulated by a frequency demodulator, and output as an analog output J signal.

In this way, since the analog input signal is frequency-modulated and recorded on the recording medium, distortion due to the characteristics of the MRH does not appear in the signal read out and demodulated by the MRH.

<Example> Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

FIG. 1 is a block diagram of a magnetic recording/reproducing apparatus according to the present invention. 1 is a magnetic tape, and 2 is an induction thin film magnetic head (hereinafter referred to as IH) that records signals on the magnetic tape 1.
3 is a low-pass filter (hereinafter referred to as LPF) that reads the signal recorded on the magnetic tape 1, 5 is an amplifier, and 6 is a voltage controlled oscillator (hereinafter referred to as ■CO). ), 7 and 8 are counters, 9
．． 10 and 14 are monostable multivibrators (hereinafter referred to as
11 is a pulse train type recording amplifier (hereinafter referred to as PT amplifier), 12 is a reproduction amplifier, and 13 is a comparator.

Figure 2 shows the waveforms of the output signals of each part in Figure 1,
Signal “A” to signal “G” and signal “Building signal “■7”
is a voltage waveform, and waveform "I" indicates a current waveform.

The operation of the magnetic recording/reproducing apparatus configured as described above will be explained with reference to the signal waveforms shown in FIG.

When recording, an analog audio signal is sent to LPF 4.
A" is input, and its output signal is amplified like a signal "B" through a level adjustment amplifier 5.

This signal "B" is input as the control voltage of VCO6, and the frequency of its output signal is "1 input signal" [3
It is proportional to the voltage level of '''.The above V CO
The output signal of 6 is input to the counter 7, and the output signal "
C” is input to the counter 8 and is also used as a clock signal for the mono multi 9 and the mono multi 10.
is input to the monomulti 10. The counter 8 to which the signal “C” is input receives the data signal “D” and the data signal “E” (
Both output FM signals. And the data signal “
D" is input to the mono multi 9, data signal "E" is input to the mono multi 10, and a pulse signal "F" and a pulse signal "G" of a constant width are generated using the signal "C" as a trigger. Pulse signal “F” and pulse signal “G”
” is input to the PT amplifier 11 and converted into a current signal “I”. Based on this current signal “I4”, I
An FM signal is recorded on the magnetic tape l by H2 (F
M record).

By the way, when recording signals at the same level, I H2
requires more current than a wire-wound type head, so the signal
Recording the signals "D" and "E" as they are manually into II(2) consumes a lot of power. Therefore, as mentioned above, the pulse signals such as the signals "D" and "E" are recorded as the signal "H".
The power consumption is reduced by recording with a current waveform like this. This type of recording method is called the pulse train method, and although it is considerably influenced by the gap width of the MRH 3 that extracts the signal recorded on the magnetic tape I and the pulse width of the recording signal, it basically records the signal "D" as is. You can record the equivalent of recording.

During playback, a signal extracted from the magnetic tape 1 by the MRH 3 and amplified by the playback amplifier 12 is
I" is input to the comparator 13, and a level higher than a predetermined value is taken out and a signal ", ■°" is output. Here, I1 and I2 in FIG. 2 are the voltage comparison levels of the comparator 13. In this way, the voltage comparison level is set to 2.
This is because the comparator 13 has hysteresis. This is to prevent the comparator 13 from malfunctioning due to noise as indicated by i.

Next, the signals ", ■" are input to the monomulti 14, and the signal "K" is obtained using the rising edge as a trigger. This signal "K" has the same level "H" width, so when it passes through the LPF 15, a signal "L" is obtained.

That is, this signal "L" is a demodulated signal of the input audio signal "A".

Here, the reason why the amplitude of the signal "I" is not constant is M
This is due to the characteristics of RH3. For this reason, if the signal recorded by FM modulation is not recorded by AC bias method or PW
When a signal recorded using the M method or the like is reproduced, the reproduced signal becomes a distorted signal like the signal "Q" in FIG. 4.

However, in the magnetic recording/reproducing apparatus of the present invention, the analog input audio signal is FM-modulated, and the FM-modulated pulse signal is sent to the pulse train type PT amplifier 1. l
Since it is converted into a current signal by H2 and recorded on the magnetic tape 1 by H2, it is used as a reproduction head when demodulating the signal recorded on the magnetic tape 1 as described above.
Even if Tt is used, the signal recorded on the magnetic tape 1 can be demodulated without being affected by the characteristics of the MRH 3. Therefore, the MRH3 can be used as a reproducing head, and the reproducing head can be made compact and multi-track.

<Effects of the Invention> As is clear from the above, the magnetic recording and reproducing apparatus of the present invention converts an analog input signal into a frequency-modulated pulse signal by the frequency modulation section, and performs a signal based on the converted frequency-modulated pulse signal. The pulse train generating section records a signal on a recording medium using a pulse train method via an indakunyong thin film magnetic head, and the signal recorded on the recording medium is read by a thin film magnetoresistive head. Since the signal is frequency demodulated by the frequency demodulation section and the output signal is reproduced,
A distortion-free output signal can be reproduced without being affected by the characteristics of the thin film magnetoresistive head. Therefore, it is possible to easily increase the number of tracks by using a thin film magnetoresistive head for the reproducing head.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a magnetic recording/reproducing apparatus according to an embodiment of the present invention, FIG. 2 is a timing diagram of each output signal in the above embodiment, FIG. 3 is a block diagram of a conventional magnetic recording/reproducing apparatus, and FIG. The figure is a timing diagram of each output signal in the conventional example. 1. Magnetic tape, 2. Thin-film magnetic head, 3. Thin-film magnetoresistive head, 4.15. Low-pass filter, 5. Amplifier.
6 ・Voltage controlled oscillator, 7, 8 ・Counter, 9.10
．． 14. Monostable multi-by-break, 11. Pulse train recording amplifier, 12. Reproduction amplifier,

Claims (1)

[Claims] (1) It has an induction-type thin-film magnetic head for recording, a thin-film magnetoresistive head for reproduction, and a pulse train generation section, and records a signal on a recording medium by a pulse train method, and records a signal on the recording medium. In a magnetic recording and reproducing device for reproducing signals recorded on a magnetic recording device, a frequency modulation unit converts an analog input signal into a frequency-modulated pulse signal and outputs the signal to the pulse train generation unit, and the thin-film magnetoresistive head A magnetic recording/reproducing device characterized by comprising a frequency demodulating section that demodulates the frequency of a signal read from the recording medium.