JPH0724084B2 - Signal recording device and signal recording method in VTR - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a VTR that multiplex-records and reproduces an audio signal and a video signal on the same track, and particularly when used as an audio-only recorder in a long time mode. The present invention relates to a signal recording method and a device therefor.

[Conventional technology]

Conventionally, as a method for recording an audio signal of a home-use VTR for the purpose of improving sound quality, a technical research report of the Institute of Electronics and Communication Engineers
"HiFiVH" by Mr. Miura and 5 others in MR83-20 (1983)
As described in the document entitled "SVTR System Development", a method of multiplexing FM audio signals using a dedicated audio signal recording melt rotary head on a video signal track for recording a video signal is adopted.

[Problems to be solved by the invention]

The playback sound quality of this Hi-Fi VTR is far superior to the conventional VTR, and it is used by audiophiles as a master recorder exclusively for voice. Especially when used in EP (3x playback time) mode, it is possible to record for a long time of up to 8 hours, and it is superior to the cassette recorder not only in terms of sound quality but also in terms of this long recording, so this usage has become established. is there.

By the way, when using it for this audio only,
-Because the video signal is not recorded in FiVTR, the image of the noise signal as it is out of synchronization is displayed on the image monitor, which gives the user considerable discomfort.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a signal recording method and an apparatus thereof for a VTR that does not cause a user discomfort.

[Means for solving problems]

That is, the features of the new recording method and apparatus according to the present invention are that a simple simulated image pattern generator is provided and the simulated image pattern is recorded at a lower recording level when used exclusively for audio. Is. Furthermore, another feature of the present invention is to provide a circuit for detecting whether or not a video signal to be recorded is input, and when the above video signal is not input, it is determined that only the audio is used, and the above-mentioned simulated video pattern is set. This is something I tried to record.

[Action]

As a result, even when a tape recorded only for audio is reproduced, the simulated video pattern recorded at the same time is displayed on the screen monitor, so that the user does not feel uncomfortable. Furthermore, since the recording level of this simulated video pattern signal is lowered, the reproduced sound quality can be improved. Further, the video signal input detection circuit automatically records the simulated video pattern when no video signal is input, so that no malfunction occurs.

〔Example〕

An embodiment of the signal recording method and apparatus according to the present invention will be described below with reference to FIG. In the figure, 1 is an input terminal for the video signal S ₁ to be recorded, 2 is a circuit for generating a simulated video pattern signal S ₂ to be recorded in the case of audio-only recording, and 3 is whether or not the video signal S ₁ is input. Circuits 4 and 8 are switch circuits whose switching points (a) and (b) are controlled by the output signal of the video input detection circuit 3, and 5 and 9 are switch circuits which are manually controlled as function switches. 6 is a recording processing circuit for performing FM modulation and low frequency conversion on the luminance signal and color signal of the input video signal S ₁ or simulated video pattern signal S ₂ , 7 is an attenuator, 10 is a recording amplifier, 11 is an output terminal Is.

First, when normal audio and video are simultaneously recorded, the contact points of the manual switch circuits 5 and 9 are both connected to the direction (b), and it is detected that the video signal S ₁ to be recorded is input. The contacts of the switch circuits 4 and 8 detected by the circuit 3 are both connected to the direction (b). Therefore, the video signal S ₁ is input to the video signal recording processing circuit 6 and its output signal
S ₃ is recorded directly through the recording amplifier 10 and the output terminal 11.

Next, when recording as audio only, two methods are possible. The first is a method of manually switching the contacts of the function switch circuits 5 and 9 to (a), and the second is a method of not inputting the video signal S ₁ without operating the function switch circuits 5 and 9. . In the first case, the output signal S ₂ of the simulated video pattern generation circuit ₂ is input to the video signal recording processing circuit 6 regardless of the presence or absence of the input of the video signal S ₁ , and the output signal S ₃ is the attenuator 7 Recording amplifier
It is recorded through 10 and the output terminal 11. That is, the simulated video pattern is recorded with the recording level lowered. On the other hand, in the second case, the video signal input detection circuit 3 detects that the video signal S ₁ is not input, and the contacts of the switch circuits 4 and 8 are both switched to the direction (a). Therefore, in this case, whichever the contact points of the function switch circuits 5 and 9 are, the simulated video pattern signal S ₂ is input to the video signal recording processing circuit 6, and the output signal thereof is the same as in the first case. S ₃ is recorded through the attenuator 7, recording amplifier 10 and output terminal 11.

FIG. 2 is a waveform diagram showing an example of the simulated video pattern signal S _{2 according to} the present invention. (A) is a pattern in which the entire monitor screen has a constant brightness level, and (B) is a pattern in which the brightness changes stepwise with a slight change. If monochrome is not enough, a monochromatic color signal may be added. Further, it may be a pattern in which the reason why the recording medium is dedicated to voice is displayed as a character. In any case, the present invention is not limited by the type of this simulated video pattern,
The feature of the present invention resides in that these simulated video patterns are recorded at the time of audio only.

Next, another feature of the present invention, that is, the recording of the simulated image pattern at a lower recording level will be described in detail.

FIG. 3 is a characteristic diagram showing the reproduction level when the recording level of the video signal is changed.
3-20). The horizontal axis shows the optimum recording current I
Recording current I / Iopt of luminance signal normalized by opt, vertical axis is reproduction output level [dB], (A) luminance signal reproduction output characteristic, (B) 1.7 MHz audio FM signal reproduction output Show the characteristics. Since the audio signal is overwritten and erased by the luminance signal in this way, the reproduction output thereof sharply decreases as the recording level of the luminance signal increases. Normally, when recording audio and video simultaneously, the recording level of the luminance signal is set to Iopt, but the level of the audio signal at this time is low as shown in the figure. However, in the case of audio only, the simulated video pattern to be recorded does not have much information amount, and it is not necessary to set the recording level to the normal setting value Iopt. The purpose of the simulated image pattern is that the image displayed on the image monitor does not cause user discomfort, so even if the recording level is reduced by 25%, the S / N of the reproduced image is about 1 dB.
It only deteriorates. On the other hand, the reproduction level of the audio signal is increased by about 7.5 dB, and the audio quality is greatly improved. Moreover, if the S / N deterioration of the image is more tolerated, the S / N of the voice is further improved.

FIG. 4 is a block diagram showing another embodiment of the present invention applied to a VTR for recording a PCM-converted audio signal. In the figure,
The video signal S ₁ supplied to the input terminal 1 or the output signal S ₂ of the simulated video pattern generating circuit ₂ is converted by the video signal recording processing circuit 6 into a luminance signal and a chrominance signal, respectively, into bands as shown by the solid line in FIG. And is recorded on the magnetic tape 13 by the rotary heads 12a and 12b. On the other hand, the audio signal supplied to the input terminal 20 is converted into a digital signal by the AD converter 21,
The digital signal processing circuit 22 adds a synchronizing signal, an error correction code, etc., and interleaves it. Further, it is converted into a band as shown by a broken line in FIG. 5 by the digital modulation circuit 23, and is recorded on the same track of the video signal of the magnetic tape 13 by the rotary heads 25a and 25b for exclusive use of the audio through the recording amplifier 24.

In the case of audio only, the operation of the video input detection circuit 3 and the changeover switches 4 and 5 is exactly the same as that of the embodiment shown in FIG. The present embodiment differs from the embodiment shown in FIG. 1 in that the voltage gain of the recording amplifier 10 is lowered as a method of lowering the recording level of the video signal. That is, in the recording amplifier 10 composed of the differential amplifier 101, the resistors 102, 104, 105, and the capacitor 103, the voltage gain is changed depending on whether the resistor 105 is grounded or blocked by the switch circuits 8 and 9.
The operation of the switch circuits 8 and 9 is similar to that of the embodiment shown in FIG.

〔The invention's effect〕

As described above, according to the present invention, when a VTR that multiplexly records and reproduces an audio signal and a video signal on the same track is used as an audio-only recorder, a simulated video pattern is recorded with its recording level lowered. Therefore, the distorted monitor image does not make the user feel uncomfortable, and the reproduced sound quality can be improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a signal recording system according to the present invention, FIG. 2 is a waveform diagram showing an example of a simulated image pattern according to the present invention, and FIG. 3 is a luminance signal recording current vs. luminance signal and FIG. 4 is a diagram showing main characteristics of audio signal reproduction, FIG. 4 is a configuration diagram showing another embodiment of the present invention, and FIG. 5 is a spectrum diagram of each signal recorded on a magnetic tape. 2 …… Simulated video pattern generation circuit 3 …… Video signal input detection circuit 4,5,8,9 …… Switch circuit 7 …… Attenuator

Claims (4)

[Claims] 1. A video tape recorder (VTR) for multiple recording and reproducing an audio signal on a magnetic layer portion on the same track as a video signal, and a simulated video signal generating means for generating a simulated video signal, and a magnetic tape. A video signal input switching means for selecting and switching a normal video signal or an output signal from the simulated video signal generating means as a video signal to be recorded thereon; and an output signal from the video signal input switching means. And a video signal recording level for controlling the recording level of the output signal from the video signal recording processing means when recording the output signal from the video signal recording processing means on a magnetic tape. A signal recording device in a VTR, comprising a control means. 2. The video signal recording level control means controls so as to lower the recording level as compared with the case where the normal video signal is recorded on a magnetic tape. Signal recorder for VTR. 3. A video tape recorder (VTR) which multiplex-records and reproduces an audio signal on a magnetic layer portion on the same track as a video signal, detects a video signal for recording on a magnetic tape, and outputs the video signal. As a result of the detection, when the video signal is not detected, the output signal from the simulated video signal generating means is selected, the selected signal is signal-processed, and the recording level of the signal-processed signal is lowered. A signal recording method in a VTR characterized by controlling and recording on a magnetic tape. 4. The recording level of the signal processed signal is
Rather than recording a normal video signal on a magnetic tape,
The signal recording method in a VTR according to claim 3, wherein the recording level is lowered.