JPS63200363A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To correct the skew of an FM information signal to be reproduced and to prevent sound quality from being deteriorated, by utilizing the fact that an FM modulated component is generated in the FM information signal due to the fluctuation and the discontinuance of a time base in the process of recording and reproduction, and negating the modulated component. CONSTITUTION:A reproducing FM signal on which the fluctuation and the discontinuance of the time base due to the switching of a head, etc., are added is divided into two groups, and one of them is inputted to an FM demodulation circuit 49 via a BPF48 which passes only a pilot signal. Next, the phase of an obtained demodulation signal is inverted at an inversion amplifier circuit 50 capable of performing gain control, and the signal is inputted to an FM modulation circuit 51. Also, the other one of the groups is inputted directly to the circuit 51, and the fluctuation and the discontinuance of the time base are corrected. Afterwards, corrected signals are demodulated at an L and an R channel demodulation circuits 54 and 55 via an L and an R channel carrier signal band-pass filters 52 and 53, and signal processings opposite to the ones performed at the time of recording are applied on them at noise reduction circuits 56 and 57, and they are outputted from terminals 60 and 61 via amplifiers 58 and 59.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Field of Application) The present invention aims to solve the problem of fluctuations in the time axis that occur when magnetically recording and reproducing information signals such as video signals and audio signals using a rotating head. The present invention relates to a magnetic recording/reproducing apparatus that corrects discontinuity (hereinafter referred to as skew).

(Prior Art) Conventionally, in a video tape recorder (hereinafter referred to as a VTR), video signals are recorded on a magnetic tape using a rotating head, and audio signals are recorded on a recording track in the longitudinal direction of the magnetic tape using a fixed head. I was recording it. However, in recent years, the sound quality has been dramatically improved by FM modulating the audio signal and recording and playing it using a rotating head.
TR is popular.

As an example of this high-fidelity VTR, the recording method of a high-fidelity VTR of the Vl-IS system will be explained with reference to FIGS. 4 to 6.

Figure 4 does not show the frequency spectrum of the recording method in the VH3H3 type IFAI VTR.In video recording, the bands of the low color subcarrier A and the FM luminance signal B are distributed as shown in Figure 4(a). In audio recording, audio FM waves C and D are distributed between the bands of the low-range color subcarrier A and the FM luminance signal B, as shown in FIG. 4(b). The L channel audio signal is FM-modulated on carrier C of 1.3 MHz, and the R channel audio signal is FM modulated on carrier D of 1.7 MHz.

FIG. 5 explains the recording method in a VH8 system high-fidelity VTR. First, an audio signal is recorded on a recording track of a magnetic tape 1 using a rotary head 2 exclusively for audio as shown in FIG. 5(a). Deep recording is performed at an azimuth angle of ±30° in a state close to saturation recording, and then, as shown in FIG. I'm sleeping and recording.

Figure 6 shows the high-fidelity V1-R of the V1-IS system.
As shown in FIG. 6(a), the video recording system receives a video signal through an input terminal 11 to a video signal recording circuit 12, and outputs a video recording signal suitable for magnetic recording. is converted into a magnetic head 13 for video recording.
．． The information is recorded on the magnetic tape at step 14. In the audio recording system, as shown in FIG. 6(b), the audio signal passes through an input terminal 15, passes through a noise reduction circuit 16 that significantly reduces noise, is FM modulated by an FM modulation circuit 17, and is then FM-modulated by a recording amplifier. Audio recording magnetic head 19.20 via circuit 18
recorded on magnetic tape.

By the way, in the above-mentioned method of time-divisionally recording onto multiple recording tracks by diagonally scanning the magnetic tape with a rotating head, the switching point between one recording track and the next recording track during playback is This has the disadvantage that skew occurs in the audio signal, which significantly deteriorates the sound quality of the reproduced audio signal. In reality, this sound quality deterioration is considerably suppressed by the noise reduction circuit, but the sound quality deterioration also occurs in the noise reduction circuit, and the recording circuit configuration is not sufficient for high-fidelity playback. Furthermore, in order to prevent the above-mentioned skew from occurring, it is possible to improve the mechanical precision and expansion/contraction of the magnetic tape, which are the causes of the skew, but this increases production costs and is a problem for home VTRs.

(Problems to be Solved by the Invention) As described above, the conventional apparatus has a problem in that it is not possible to obtain sound quality sufficient for high-fidelity playback due to the generation of noise.

Therefore, the present invention is intended to eliminate the above problems.
It is an object of the present invention to provide a magnetic recording and reproducing device that can prevent deterioration of sound quality by correcting skew of reproduced audio signals and the like.

[Structure of the Invention] (Means for Solving the Problems) The magnetic recording and reproducing apparatus of the present invention includes means for generating a carrier signal for time axis correction, a means for generating a carrier signal for time axis correction, and an F M While a means for frequency multiplexing and recording the information signal carrier signal is provided, in the reproducing circuit, the time axis correction signal is extracted by the extraction means from the reproduced signal, and the time axis correction signal is extracted from the time axis correction carrier signal. By FM demodulating the FM modulation component caused by the axis fluctuation and discontinuity using the FM demodulation means, and using the signal obtained by inverting the phase of the demodulated signal, the reproduced FM information signal is FM modulated using the FM modulation means. The skew-corrected FM information signal is demodulated at 19.

(Function) In the present invention, the FM modulation component is generated in the FM information signal due to fluctuations and discontinuities in the time axis that occur during the recording and reproducing process, and by canceling this FM modulation component, the reproduced FM information This is to correct the skew of the signal.

(Example) The present invention will be described below based on the example shown in the drawings.

FIG. 1 is a block diagram showing an audio system circuit of a magnetic recording/reproducing apparatus according to an embodiment of the present invention.

In FIG. 1(a), the audio signals of the L and R channels pass from input terminals 31 and 32 to noise reduction circuits 33 and 34, respectively, and are output as FM modulated signals by FM modulation circuits 35 and 36. be done. Next, L
, R channel audio FM signals are added to an unmodulated carrier signal (hereinafter referred to as a pilot signal) for time axis correction from the launcher 37 in an adder 38, and the added signal is sent via a recording amplifier circuit 39. The signal is then supplied to the audio recording magnetic head 40, 41 and recorded on a magnetic tape (path shown). J3 and magnetic heads 40 and 41 are attached to a rotating cylinder to constitute a rotating head.

The frequency spectrum of the sound 1h signal recorded on the magnetic tape is as shown in FIG.

The above pilot signal G exists between the bands of the L channel audio carrier E and the R channel audio carrier F, and the L channel audio signal is transmitted to the FM modulation circuit 35.
The audio signal of the R channel is FM modulated by the audio main 11 rear (Y) in the FM modulation circuit 36, frequency multiplexed with the pilot signal G, and recorded on a magnetic tape. There is.

In FIG. 1(b), the audio reproduction magnetic head 42.4
3 reproduces the recorded signal recorded on the magnetic tape, and passes it through the reproduction amplifier circuits 44 and 45 to the selector switch 47.
given to. Note that the magnetic heads 42 and 43 may be the magnetic heads 40 and 41 that are also used for audio reproduction.

On the other hand, a switching signal is applied to a changeover switch 47 via a changeover signal input terminal 46, and the changeover switch 47 is controlled by this changeover signal, and is alternately switched every one field period. The signals from .43 are alternately selected and output as a continuous reproduction FM signal. The frequency spectrum of this reproduced M signal is the same as that shown in Figure 2, and sound i also consists of carriers E, F and pilot signal G, but due to changes in the head used during recording and reproduction, etc., the time axis is The signal has fluctuations and discontinuities added to it. Next, this reproduced FM signal is divided into two systems, one of which is input to four FM demodulation circuits via a bandpass filter (Br'F) 48 that passes only the pilot signal, and the phase of the demodulated signal can be gain controlled. The reproduction FM signal, which is the output of the changeover switch 47, is
A modulation circuit 51 performs FM modulation to obtain an output in which fluctuations in the time axis and discontinuous components in J3 are corrected in the reproduced FM signal. The output signal of the FM modulation circuit 51 is then passed through the L channel carrier signal band filter 52 and the R channel carrier signal t? Via the rear signal bandpass filter 53, it is demodulated by an L channel demodulation circuit 54 and an R channel demodulation circuit 55, and then subjected to signal processing opposite to that at the time of recording in noise reduction circuits 56 and 57, and then output to an output amplifier circuit 58. ．．
59 and is output from the blind spot output terminals 60 and 61.

Next, the skew correction operation of the reproduced FM signal in the above circuit system will be explained with reference to FIG.

FIG. 3(a) shows the output signal a of the bandpass filter 48. The sample wave of this signal a is the pilot signal @G, but it is FM-modulated due to fluctuations and discontinuities in the time axis during the recording and reproducing process. This is a signal. Figure 3 (b) shows a signal obtained by FM demodulating the signal in Figure 3 (a) using four FM demodulation circuits, and the level of this signal changes due to fluctuations and discontinuities in the time axis. are doing. FIG. 3(C) shows a signal Fjc obtained by inverting the phase of the signal in FIG. It's changing. The output of the FM modulation circuit 51 obtained in this way is demodulated in the same manner as the FM modulated signal in FIG. Continuity is corrected.

Although the above-mentioned embodiment shows skew correction of an audio signal, the present invention is not limited to & point signals, but can be applied to other information signals such as video signals.

[Effects of the Invention] As described above, according to the present invention, fluctuations and discontinuities in the time axis that occur when information signals are magnetically recorded and reproduced using a rotating head are compensated for, and the reproduced sound and screen are improved. Quality can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the electrical recording/reproducing apparatus of the present invention, FIG. 2 is an explanatory diagram showing the frequency spectrum of the recording signal in FIG. 1, and FIG. 3 is a diagram showing each part of the circuit in FIG. A waveform diagram showing the signal waveform. Figure 4 is an explanatory diagram showing the frequency spectrum of the recording method in a VH8 system high-fidelity VTR. Figure 5 is a VH8 system high-fidelity V.
FIG. 6 is a block diagram showing a recording circuit configuration in a conventional VH8 system high-fa-fi TR. 31.32... Audio signal input terminal, 35.36... FM modulation circuit, 37... Oscillator, 38... Adder, three...
... Recording amplifier circuit, 40.41... Recording head, 42.43... Playback head, 44.45... Playback amplifier circuit, 47... Changeover switch, 48... Bandpass filter,
49... FM demodulation circuit, 50... Inverting amplifier circuit, 51... FM modulation circuit, 52.53... L, R channel band filter, 54
．． 55...L, R channel demodulation circuit, 58.59.
...L, R channel output amplifier circuit. Agent Patent Attorney Nori Megumi Chika Yudo Hiroshi Uji Figure 2 Figure 4

Claims (1)

[Claims] In a magnetic recording and reproducing device that magnetically records and reproduces an information signal onto a recording track of a tape-shaped recording medium using a rotating head, a recording system circuit is provided with a signal having a frequency domain different from that of a carrier signal for an FM information signal. means for generating a carrier signal for time axis correction, and means for multiplexing the carrier signal for time axis correction with the FM information signal and recording it on the tape-shaped recording medium; means for extracting the carrier signal for time axis correction from a signal reproduced from a recording medium; and FM demodulation of FM modulation components caused by fluctuations and discontinuities in the time axis present in the extracted carrier signal for time axis correction. FM demodulation means for inverting the phase of the FM demodulated signal; FM modulation means for FM modulating the FM information signal reproduced from the tape-shaped recording medium using the signal from the inversion means; A magnetic recording and reproducing device characterized by comprising means for demodulating an FM information signal that has passed through an FM modulation means.