JPS62141676A - Magnetic recording and reproducing circuit - Google Patents

Abstract

PURPOSE:To distinguish reproduced signals of high density recording with fidelity by adding a time reference signal (synchronizing signal) to recording signals at the time of magnetic recording, and oscillating a variable frequency oscillating circuit (VFO circuit) by reproducing synchronizing signal voltage. CONSTITUTION:Recording signals 1 are inputted to a modulating circuit 2 in a recording circuit, and time compressed information signals 3 and synchronizing signals 4 utilized for a VFO circuit are generated. Input signals 28' produced in a reproducing circuit are the same in relative positional relation with the synchronizing signals 4 obtained by the modulating circuit 2 at the time of recording, and accordingly, the VFO circuit 31 can output an exact distinguishing window signals 32. The synchronizing signals are recorded in lower frequency compared with the information signals, and the synchronizing signals in the reproduced signals become larger reproduction voltage compared with the information signals, and accordingly, the separation of the synchronizing signals and information signals becomes easy, and the reproduction of high density recording becomes possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a magnetic recording device, and particularly to a recording/reproducing circuit suitable for high-density recording.

[Background of the invention]

In a magnetic recording device, the magnetized recording medium is driven by a motor, etc., so the reproduced signal cannot be obtained at accurate time intervals as during recording, and is affected by uneven rotation of the motor, expansion and contraction of the recording medium, etc. It becomes a signal. For this reason, the conventional method is to use an oscillation circuit that oscillates at a frequency synchronized with the reproduced signal, as described in Japanese Patent Application Laid-Open No. 52-123214, that is, a variable frequency oscillation circuit (hereinafter referred to as a VFO circuit).
0scillator) has been used to separate, ie, discriminate, the signal portions present in the reproduced signal. However, as the recording density increases, factors that affect the time interval of the reproduced signal include not only external factors such as the aforementioned uneven rotation of the motor and expansion and contraction of the recording medium, but also pattern peaks caused by high-density recording itself. The influence of deterioration of the S/N ratio due to shifts and reductions in reproduction voltage has accounted for a large proportion. For this reason, conventional VFO circuits using reproduced signals are directly affected by this, and it has become inevitable that certain limits will arise in increasing the reliability of signal reproduction.

[Purpose of the invention]

An object of the present invention is to provide a recording/reproducing circuit suitable for faithfully discriminating reproduction signals of cylindrical density recording, while eliminating the above-mentioned drawbacks.

[Summary of the invention]

The present invention focuses on the fact that the saturation value of the reproduction readout voltage with respect to the recording current differs depending on the frequency of the recording signal, and by adding a dedicated time reference signal (hereinafter referred to as a synchronization signal) to the VFO circuit at a low frequency into the recording signal, a large reproduction VFO with synchronous signal voltage
It is characterized by highly precise oscillation of the circuit and high discrimination reliability.

[Embodiments of the invention]

Embodiments of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 shows a recording circuit, and FIG. 2 shows a reproducing circuit. Third
The figure shows the signals in FIGS. 1 and 2 in the form of a time chart.

In FIG. 1, a recording signal 1 is input to a modulation circuit 2. In FIG.

The purpose of the modulation circuit is to generate an information signal 5 which is a temporally compressed recording signal 1, and a synchronization signal 4 used in the ■℃ circuit described later.The signal 6 generated by the NOR gate 5 is transmitted to the triggerable FF 7. This results in a signal of 7'. On the other hand, the synchronizing signal 4 is also input to the triggerable FF 9, and its output (g 9' turns the transistor 12 on and off, and connects or shorts the current source setting resistor R2. Therefore, the current I2-I flowing through the recording head 8 is Third
The waveform is shown in FIG. 11-10.

In FIG. 2, the 150 waveform becomes the waveform shown in FIG. 5, 15 because of the recording current shown in FIG. 3, 11-10.

The output waveform 17 of the differentiating circuit 16 is divided into 2 by the limiter 21.
Output waveforms sliced at positions 1' and 21'' 23 and 2
Get 4. On the other hand, the waveform 15 is transferred to the amplifier circuit 29. A waveform 25 is obtained by passing through a zero cross circuit 30. The gate circuits 26, 27, and 28 generate an input signal 28' for the "O" circuit. The signal 28' has the same relative position as the synchronizing signal 4 obtained by the recording/reproducing circuit. The VFOu path 31 can output an accurate discrimination window signal 32.

Filter 18. Zero cross circuit 19. Discrimination demodulation circuit 20
is constructed using conventional technology.

〔Effect of the invention〕

According to the present invention, since the synchronization signal is recorded at a lower frequency than the information signal, the synchronization signal in the reproduced signal has a larger pressure voltage than the information signal trap. The first effect of this is that it is easy to separate the synchronization signal and the information signal. Second, the synchronization signal, which is more important than the alert signal, is less susceptible to the effects of noise, etc. (@3) The magnetization changes before and after the synchronization signal are relatively far apart, so the effects are less affected by noise. Fourthly, so-called write compensation, which temporally compensates for the influence of adjacent magnetization changes during recording, which has been practiced in the past, has become more effective.

The above effects enable even higher density recording and reproduction.

[Brief explanation of drawings]

FIG. 1 is a recording circuit diagram of an embodiment of the present invention, FIG. 2 is a reproduction circuit diagram, and FIG. 3 is a waveform and time chart of the main parts of FIGS. 1 and 2. 1...Recorder number, 2...Modulation circuit, 6.
...Information signal, 4...Synchronization signal, 5...N
OR gate, 6...NOR gate output, 7...
・Information signal FF, 8...recording head, 9...
Synchronization signal FF, 10... Recording current, 12... Current value switching transistor, 13... Playback head,
14... Preamplifier, 16... Differential circuit, 1
8... Filter, 19... Zero cross circuit, 20.
...Discrimination demodulation circuit, 21...Limiter. one\

Claims (1)

[Claims] 1. In magnetic recording, a recording signal is modulated into a low-frequency synchronization signal and a high-frequency information signal, and the synchronization signal is used by a recording circuit that flows a large recording current compared to the information signal, and during reproduction, the synchronization signal is A magnetic recording/reproducing circuit characterized in that a synchronization signal and an information signal are divided based on the difference in reproduction voltage between the reproduction signal and the reproduction signal, and a variable frequency oscillator for information discrimination is synchronized only by the synchronization signal.