JP2627967B2 - Video tape recorder - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video tape recorder, and more particularly, to a video tape recorder having a rotating audio head and a rotating video head for performing FM superposition recording, a so-called hi-fi video. About.

<Prior Art> FIG. 4 is a block diagram of a conventional Hi-Fi video. In FIG. 4, 1 is an FM modulator for FM-modulating a luminance signal, and 2 is a band for securing a band of a low-frequency conversion chroma signal. High-pass filter, 3 is a low-pass converter for down-converting the chroma signal, 4 is a low-pass filter, 5 is a recording amplifier for amplifying the multiplexed FM luminance signal and low-pass converted chroma signal, 6
Is a rotary transformer, 7 is a rotary video head, 21 is a magnetic tape, 8 is a reproduction amplifier for amplifying a reproduction signal, 9 is a high-pass filter for cutting a low-frequency conversion chroma signal, and 10 is a low-pass filter for extracting a low-frequency conversion chroma signal. Filter.

11 and 12 FM sound signals of each channel
FM modulator for modulating, 13 and 14 are low-pass filters, 15 is a recording amplifier for amplifying the mixed FM audio signal, 16 is a rotary transformer, 17 is a rotating audio head, 18 is a reproducing amplifier for amplifying a reproduced signal, 19, Reference numeral 20 denotes a band pass filter for separating the audio signal of each channel. Note that 22
Numerals 25 are head switches for switching between recording and reproduction.

In such a Hi-Fi video, as shown in the cross-sectional view of the magnetic tape 21 in FIG.
The FM audio signal is recorded to the depth of the magnetic tape 21 by the 17, and then the video signal is recorded on the surface layer of the magnetic tape 21 by the rotating video head 7 having a different azimuth angle from the rotating audio head 17. A record is made.

<Problems to be Solved by the Invention> FIG. 6 shows a frequency spectrum in such FM superimposed recording, where A is a low-band conversion chroma signal having a center frequency of 629 kHz, and B and C are 1.3 MHz and 1.7 MHz. Are the center frequency, left and right FM audio signals, and D is the FM luminance signal.

As shown by hatching in FIG. 6, the FM audio signals B and C
And the FM luminance signal D overlap with each other, and the interference cannot be suppressed only by the azimuth loss. In particular, the right channel FM audio signal C has a large number of overlapping bands, and thus is compared with the left channel FM audio signal B. There is a disadvantage that the C / N ratio deteriorates.

Therefore, it is conceivable to narrow the bandwidth of the FM luminance signal D. However, when the bandwidth is narrowed, the resolution is reduced and the image quality is deteriorated.

The present invention has been made in view of the above points,
An object is to improve the C / N ratio of an FM audio signal without lowering the resolution.

<Means for Solving the Problems> In order to achieve the above object, the present invention is configured as follows.

That is, while the FM audio signals of both channels are deeply recorded on the magnetic tape by the rotating audio head, the frequency-modulated FM luminance signal and the low-frequency conversion chroma signal are multiplexed and the rotating video head records the FM audio signal on the surface layer of the magnetic tape. In a video tape recorder that records and reproduces a signal recorded on the magnetic tape by the two rotating heads,
The recording system circuit includes a first equalizer circuit for lowering an amplitude characteristic of an FM audio signal frequency band of the FM luminance signal, and the reproduction system circuit includes the FM reproduced by the rotating video head.
A second equalizer circuit is provided for increasing the amplitude characteristics of the luminance signal in the FM audio signal frequency band.

<Operation> According to the above configuration, the amplitude characteristics of the FM audio signal frequency band of the FM luminance signal are reduced and recorded by the first equalizer circuit, and at the time of reproduction, the FM audio signal frequency band of the FM luminance signal is reduced by the second equalizer circuit. Since the amplitude is corrected, the interference between the FM luminance signal and the FM audio signal can be suppressed without reducing the bandwidth of the FM luminance signal.
It is possible to improve the C / N ratio of the FM audio signal.

<Example> Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of a Hi-Fi video according to an embodiment of the present invention.
With the same reference numbers.

In the figure, reference numeral 1 denotes an FM modulator for FM-modulating a luminance signal,
2 is a high-pass filter for securing the band of the low-frequency conversion chroma signal, 3 is a low-frequency converter for low-frequency conversion of the chroma signal, 4 is a low-pass filter, 5 is a multiplexed FM luminance signal and a low-frequency conversion chroma signal. , A rotary transformer, 7 a rotating video head, 21 a magnetic tape, 8 a reproducing amplifier for amplifying a reproduced signal, 9 a high-pass filter for cutting low-frequency converted chroma signals, and 10 a low-frequency converting This is a low-pass filter for extracting a chroma signal.

11 and 12 FM sound signals of each channel
FM modulators for modulating, 13 and 14 are low-pass filters, 15 is a recording amplifier for amplifying a mixed FM audio signal, 16 is a rotary transformer, 17 is a rotating audio head, 18 is a reproducing amplifier for amplifying a reproduced signal, 19, Reference numeral 20 denotes a bandpass filter for separating the audio signal of each channel. In addition,
Reference numerals 22 to 25 denote head switches for switching between recording and reproduction.

 The above configuration is the same as the conventional example shown in FIG.

The Hi-Fi video of this embodiment is configured as follows in order to improve the C / N ratio of the FM audio signal without lowering the resolution.

That is, the video signal recording system circuit is provided with a first equalizer circuit 26 for lowering the amplitude characteristic of the FM audio signal frequency band of the frequency-modulated FM luminance signal, while the video signal reproduction system circuit is provided with a rotating video head. FM reproduced by 7
A second equalizer circuit 27 for increasing the amplitude characteristic of the luminance signal in the FM audio signal frequency band is provided.

The first equalizer circuit 26 reduces the amplitude characteristic of the FM luminance signal in the FM audio signal frequency band.
By passing the signal through the equalizer circuit 26, the spectral component of the FM audio signal frequency band of the conventional FM luminance signal D shown by the broken line in FIG. 2 is attenuated as shown by the solid line. There will be almost no overlap between the signal D and the left and right FM audio signals B and C.

The second equalizer circuit 27 includes a first equalizer circuit.
26 has a characteristic opposite to that of 26, and raises the amplitude characteristic of the FM audio signal frequency band of the FM luminance signal. By passing through the second equalizer circuit 27, the conventional FM shown by the broken line in FIG. The spectral component of the FM audio signal frequency band of the luminance signal D is enhanced.

Therefore, during recording, the amplitude characteristic is reduced by the first equalizer circuit 26, and at the time of reproduction, the amplitude characteristic is increased by the second equalizer circuit 27, so that the frequency spectrum of the FM luminance signal is represented by broken lines in FIGS. The resulting spectrum is similar to the conventional one.

In FIGS. 2 and 3, A is a low-frequency conversion chroma signal.

In the video tape recorder of this embodiment, at the time of recording, the amplitude characteristics of the FM audio signal frequency band of the FM luminance signal are lowered by the first equalizer circuit 26, and at the time of reproduction, the FM luminance signal is output by the second equalizer circuit 27. Since the amplitude of the FM audio signal frequency band is corrected, it is possible to suppress the interference between the FM luminance signal and the FM audio signal without reducing the bandwidth of the FM luminance signal. It is possible to improve the C / N ratio of the signal.

In the above-described embodiment, the first equalizer circuit 26 is separately provided in the recording system circuit. However, as another embodiment of the present invention, the first equalizer circuit 26 is provided in the high-pass filter 2 for securing the band of the low-frequency conversion chroma signal. The same characteristics as those of the equalizer circuit 26 may be provided, and the high-pass filter 2 may also serve as the first equalizer circuit 26.

<Effects of the Invention> As described above, according to the present invention, the amplitude characteristics of the FM audio signal frequency band of the FM luminance signal are reduced by the first equalizer circuit and recorded, and at the time of reproduction, the FM audio signal frequency band of the FM luminance signal is reproduced. Is corrected by the second equalizer circuit, so that the interference of the FM luminance signal with the FM audio signal can be suppressed without reducing the bandwidth of the FM luminance signal, thereby increasing the C / N ratio of the FM audio signal. Can be improved.

In addition, since the reproduction system circuit is provided with the second equalizer circuit for restoring the FM luminance signal component lost at the time of recording, it is possible to suppress the deterioration of the image quality of the reproduced video, particularly the resolution.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG.
FIG. 3 is a frequency spectrum for explaining characteristics of the second equalizer circuit, FIG. 3 is a block diagram of a conventional example, and FIG. 5 is a diagram for explaining FM superposition recording. FIG. 6 is a frequency spectrum of FM superposition recording. 7 ... Rotating video head, 17 ... Rotating audio head, 21 ... Magnetic tape, 26,27 ... First and second equalizer circuits.

Claims (1)

(57) [Claims] An FM audio signal of both channels is deeply recorded on a magnetic tape (21) by a rotating audio head (17), and a frequency modulated FM luminance signal and a low-frequency conversion chroma signal are multiplexed to produce a rotating video signal. A video tape recorder for recording on a surface layer of the magnetic tape (21) by a head (7) and reproducing a signal recorded on the magnetic tape (21) by the rotating heads (17) and (7). The circuit includes a first equalizer circuit (26) for reducing an amplitude characteristic of the FM luminance signal in a frequency band of an FM audio signal, and a reproduction system circuit includes a first equalizer circuit (26) for reproducing the FM luminance signal reproduced by the rotary video head (7). A video tape recorder comprising: a second equalizer circuit (27) for increasing an amplitude characteristic of an audio signal frequency band.