JP3030925B2 - Magnetic recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus using a frequency multiplexing technique.

[0002]

2. Description of the Related Art FIG. 2 shows a configuration of a signal processing circuit of a conventional VTR (magnetic recording / reproducing apparatus). First, recording will be described. The luminance signal input from the luminance signal input terminal 1 is
Luminance signal processing circuit 2, frequency modulation circuit 3, FM audio frequency trap 4, low-frequency conversion chroma frequency trap 5,
And input to the mixing circuit 6. The chroma signal input from the chroma signal input terminal 7 passes through the chroma signal processing circuit 8 and the low-frequency conversion circuit 9 and is input to the mixing circuit 6 by the LPF 10 to remove unnecessary components and is superimposed on the luminance signal. You. The audio signal input from the audio signal input terminal 11 is
2. After passing through the frequency modulation circuit 13, the LPF 14 removes unnecessary components and inputs the mixed signal to the mixing circuit 6, where it is superimposed on the luminance signal. The recording signal output from the mixing circuit 6 is amplified by the recording amplification circuit 15 and recorded on the magnetic tape 17 via the video head 16.

Next, reproduction will be described. A signal reproduced from the magnetic tape 17 via the video head 18 is amplified by the reproduction amplifier 19 and the BPF 20,
The chroma signal subjected to the low-frequency conversion by the BPF 23 and the audio signal subjected to the frequency modulation are separated. BPF20
The low-frequency-converted chroma signal output from this is converted into a chroma signal by a chroma reproduction signal processing circuit 21 and output from a chroma output terminal 22. The frequency-modulated audio signal output from the BPF 23 is demodulated into an audio signal by an audio demodulation circuit 24, and is output to an audio output terminal 26 through an audio reproduction signal processing 25.

On the other hand, a luminance signal is obtained by converting a reproduced signal output from the reproducing amplifier circuit 19 into a low-frequency-converted chroma signal and a frequency-modulated audio signal by a low-frequency conversion chroma frequency trap 27 and an FM audio frequency trap 28. After being attenuated by the luminance signal demodulation circuit 29, the signal is output to the luminance signal output terminal 31 through the reproduction luminance signal processing circuit 30.

[0005]

However, in the above configuration, there is crosstalk to the chroma signal due to the lower sideband of the luminance signal frequency-modulated during recording, and the S / N ratio of the chroma is degraded, resulting in poor audio quality. The crosstalk causes deterioration of audio signal-to-noise ratio and increase in distortion, which is a problem. In reproduction, a low-frequency-converted chroma signal and a frequency-modulated audio signal remain in the reproduction signal input to the luminance signal demodulation circuit, and the SN ratio of the reproduced luminance signal deteriorates. In both recording and reproduction, since the phase characteristics of the lower band of the luminance signal frequency-modulated by the low-frequency conversion chroma frequency trap and the FM audio frequency trap change, the reproducibility of the luminance signal waveform deteriorates. Was.

An object of the present invention is to solve the above-mentioned problem and to provide a magnetic recording / reproducing apparatus having good reproducibility of a luminance signal.

[0007]

According to the present invention, in order to achieve the above object, at the time of recording, a frequency-modulated luminance signal is used.
During reproduction, the frequency band of the low-frequency-converted chroma signal and the frequency-modulated audio signal is separated by the BPF from the signal obtained by amplifying the reproduction output of the magnetic head, and the signal obtained by subtracting the signal from the original signal is recorded or recorded. It is provided with a configuration for reproducing.

[0008]

According to the present invention, in the above-described configuration, at the time of recording, the lower frequency band of the frequency-modulated luminance signal and the frequency band of the frequency-converted chroma signal and the frequency-modulated audio signal are changed without changing the phase. Can be sufficiently attenuated. At the time of reproduction, the chroma output signal and the frequency-modulated audio signal can be sufficiently attenuated without changing the phase from the amplified reproduction output of the magnetic head, so that the frequency-modulated luminance signal No crosstalk to chroma and audio due to the lower sideband is eliminated, and deterioration of the S / N ratio of chroma and audio is eliminated. Also, the reproduction signal input to the luminance signal demodulation circuit has no chroma and audio crosstalk and the phase does not change, so that the SN ratio of the luminance signal does not deteriorate,
The waveform reproducibility is improved.

[0009]

An embodiment of the present invention will be described below with reference to FIG.

First, recording will be described. The luminance signal input from the luminance signal input terminal 1 is a luminance signal processing 2,
After passing through the frequency modulation circuit 3, the BPF 36, BPF 37,
The signal is input to the delay line 32. In the BPF 36, only a signal corresponding to the frequency band of the low-frequency-converted chroma signal in the lower band of the frequency-modulated luminance signal is passed. In the BPF 37, only a signal corresponding to the frequency band of the frequency-modulated audio signal in the lower sideband of the frequency-modulated luminance signal is passed. On the other hand, the delay line 32 is a delay line having the same delay time as the BPF 36. The subtractor 33 subtracts the signal input from the BPF 36 from the signal input from the delay line 32 and inputs the signal to the delay line 34. The delay line 34 is a delay line having a delay time corresponding to the difference between the delay times of the BPF 36 and the BPF 37. At this time, BPF
The condition is that the delay time of 37 is longer than that of BPF 36. If the delay time of the BPF 36 is longer than that of the BPF 37, the positions of the BPF 36 and the BPF 37 must be exchanged. The signal output from the delay line 34 is
The input signal from the BPF 37 is subtracted by the subtracter 35 and input to the mixing circuit 6 having the same function as the conventional example. In the luminance signal input to the mixing circuit 6, a part corresponding to the frequency band of the low-frequency converted chroma signal and the frequency-modulated audio signal is deleted.

Next, reproduction will be described. The signals output from the reproduction amplifier circuit 19 are BPF20, BPF23,
The signal is input to the delay line 38. Delay line 38
Is a delay line having the same delay time as the BPF 20. The signal output from the delay line 38 is subtracted by the subtractor 39 from the input signal from the BPF 20 and input to the delay line 40. The delay line 40 is a delay line having a delay time equal to the difference between the delay times of the BPF 23 and the BPF 20. At this time, BP
The condition is that the BPF 23 has a longer delay time than the F20. In the opposite case, the order of subtraction must be reversed. This is because accurate subtraction cannot be performed if there is a delay in the delay time of the signal entering the subtractor. The signal output from the delay line 40 is input to a subtractor 41,
After subtracting the input signal from the PF 23, the signal is input to the luminance signal demodulation circuit 29. In the signal input to the luminance signal, the low-frequency converted chroma signal and the frequency-modulated audio signal are removed, and the phase characteristics are not changed.

As described above, according to the magnetic recording / reproducing apparatus of the embodiment of the present invention, at the time of recording, the frequency band of the chroma signal obtained by converting the frequency-modulated luminance signal into a low-frequency band and the frequency band of the frequency-modulated audio signal are changed. By separating the signal with the BPF and subtracting the signal from the original signal, the frequency band of the low-frequency converted chroma signal and the frequency band of the frequency-modulated audio signal in the lower band of the frequency-modulated luminance signal are phase characteristics. Can be sufficiently attenuated without changing. At the time of reproduction, a low-frequency-converted chroma signal and a frequency-modulated audio signal are obtained from a reproduced signal obtained by combining a frequency-modulated luminance signal, a low-frequency-converted chroma signal, and a frequency-modulated audio signal. Are separated by BPF, respectively.
By subtracting the signal from the reproduction signal, the reproduction signal input to the reproduction luminance signal demodulation circuit was sufficiently attenuated without changing the phase characteristics of the low-frequency-converted chroma signal and the frequency-modulated audio signal. Signal.

[0013]

As is clear from the above embodiments, according to the present invention, the noise from the luminance signal mixed into the chroma and audio signals can be reduced during recording, so that the S / N ratio of the chroma and audio signals can be improved. . During reproduction, noise from chroma and audio mixed into the luminance signal can be reduced, so that the SN ratio of the luminance signal can be improved. In addition, since the phase characteristics of the luminance signal processing can be improved for both recording and reproduction,
A magnetic recording / reproducing apparatus having good reproducibility of the waveform of the luminance signal can be provided.

[Brief description of the drawings]

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

FIG. 2 is a block diagram of a conventional magnetic recording / reproducing apparatus.

[Explanation of symbols]

 20, 23, 36, 37 Band-pass filters 32, 34, 38, 40 Delay lines 33, 35, 39, 41 Subtractors

Claims (1)

(57) [Claims] A low-frequency converted chroma signal and a frequency-modulated audio signal are recorded on a recording medium in a frequency band which can be disturbed by a frequency-modulated luminance signal, a low-frequency component of the frequency-modulated luminance signal. In the magnetic recording / reproducing apparatus, at the time of recording, the frequency band of the low-frequency-converted chroma signal and the frequency-modulated audio signal is separated from the frequency-modulated luminance signal, and the separated signal is separated from the original signal. Subtracts and attenuates the frequency band of the lower-band chroma signal and frequency-modulated audio signal from the lower band of the frequency-modulated luminance signal without changing the phase characteristics. ,
The low-frequency-converted chroma signal and the frequency-converted audio signal are separated from the synthesized reproduction signal to separate the low-frequency-converted chroma signal and the frequency-modulated audio signal from the reproduction signal. Subtract
A magnetic recording / reproducing apparatus in which a low-frequency-converted chroma signal and a reproduced luminance signal obtained by attenuating a frequency-modulated audio signal without changing its phase characteristics are input to a luminance signal demodulation circuit.