JPS5815380A - Video tape recorder - Google Patents

Abstract

PURPOSE:To remarkably improve the performance of an audio signal, independently of the performance of tapes, by multiplex recording and reproduction of PC-modulated audio signals on video signals. CONSTITUTION:An input video signal is separated into a color signal, a luminance signal, and a synchronizing signal with separation circuits 11-13. After the luminance signal is subject to processing such as emphasis at a processing circuit 15, the signal is inputted to a synthesis circuit 19 with time compression at a time axis compression circuit 16. The synthesis circuit 19 inputs a synthesis signal inserted between blank periods of the luminance signal having the blank periods through the said time axis compression with the audio signal converted into a PCM signal with time axis compression at a PCM signal processing circuit 18. An addition circuit 21 adds the output of the said modulation circuit 20 with a color signal output low-frequency-converted by a frequency conversion circuit 14 and applies to a recording head 23. In case of reproduction, the inverse operations are done with circuits 25-35, as shown in Figure.

Description

[Detailed Description of the Invention] The present invention provides a video signal from a television or a video camera,
The present invention relates to a video tape recorder that records and reproduces audio signals on tape.

A video tape recorder (VTR) separates and records video signals and audio signals on separate tracks in order to reproduce video signals with a band of several 500 ffz and audio signals with a band of several to 20 ffz.0For example, VH5 A schematic diagram of a signal track of a VTR system is shown in FIG.

In the figure, 1.2 is a video signal track, 5 and 4 are audio signal tracks, 5 is a video signal track width, 6 is a control track, 7 is a tape running direction, and 8 is a head moving direction.

The Eirin signal is recorded on the video signal track 1.2 of each channel using the 2Hmad helical scan method at a relative speed of approximately -811/##a with the tape, and the audio is recorded using a fixed head at the tape speed. , or in the 4-hour mode, recording and reproduction is performed on the audio signal track ζ4 at 1.1s/JFae.

Here, the relationship of tape speed to Eirin signal track 1.2 is only track 4Is, tape speed 'S,! -Δ-C has about 58 tones, and 1.1e*/age has about 19 tones. Even if the recording/reproducing time is improved by lowering the tape speed, the C/N ratio of the video signal deteriorates as the track width becomes narrower, but the recording wavelength remains constant. For this reason, tape's S/N characteristics have been improved and tape speeds have been lowered to enable long recording times.On the other hand, when tape speeds are lowered, recording wavelengths for audio tracks are limited, so the frequency characteristics and S/N of the tape are lower. The slower the speed, the worse it will be, so it will take a long time to record @
In the fall, the audio performance of VTH has deteriorated significantly.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and to provide a long-time VTR system in which the performance of audio signals is significantly improved.

The present invention is to significantly improve the performance of the audio signal regardless of the performance of the tape (by converting the audio signal into t-KI and multiplexing it on the video signal and reproducing it).

Next, one embodiment of the present invention will be explained with reference to the drawings.

FIG. 2 is a block diagram showing a first embodiment of the present invention. In the figure, 9 is a video signal input manually, 10 is an audio signal input,
11 is a color signal separation circuit, 12 is a luminance signal separation circuit,
1s is a synchronization signal separation circuit, 14 is a frequency conversion circuit, 15
1 is a luminance signal processing circuit, 16 is a time axis compression circuit, 17 is a synchronization circuit, 1s field q signal processing circuit, 19 is a synthesis circuit, 2
0 is an FM modulation circuit, 21 is an addition circuit, 22 is a recording/reproduction switching circuit, 23 magnetic heads, 24 is a channel switch, 25 is a save-pass filter, 26 is a frequency conversion circuit, 2
8 is an FM demodulation circuit, 29 is a luminance signal separation circuit, sO is a blind signal * circuit, 51 is a synchronization signal separation circuit, 32 is a time axis expansion circuit, ! Black is the adder circuit, 5 and 4 are the RF controllers, <
= Ri,! +5 is an M signal processing circuit, 56 is a signal output terminal, S7 is an audio signal output terminal, and 27 is an ivy circuit.

In Figure 2, the present invention goes to 2! This will be explained using the dohelical scan method. The input video signal is passed through a color signal separation circuit 11. Luminance signal separation circuit 12. The synchronous signal separation circuit 1s generates a synchronous signal.

Separate the luminance signal and synchronization signal. It is converted to a low frequency by the color signal line frequency conversion circuit 14, and is passed through the adder circuit 21t to the FM modulation circuit 201) using the FM carrier signal as a bias to the magnetic head 2! is recorded on a tape (not shown). On the other hand, the luminance signal is processed by the luminance signal processing circuit 1.
In step 5, the signal is subjected to enftysis processing and inputted to the time axis conversion (compression) circuit 16. This time axis conversion circuit 16 compresses the time axis of the luminance signal to s/s. The audio signal 10 is then subjected to M signal processing such as conversion interleaving and correction word generation in the M signal geographical circuit 18, and the time axis is compressed to less than 1 and output. Since the luminance signal in the first synchronization section Kannai is compressed on the time axis to ~A, blanks A and A are created, so the synchronization circuit 171 and the synthesis circuit 19 operate to insert S signals of the audio signal between them. This signal is FM modulated by the FM modulation circuit 20 and recorded on the tape together with the color signal.

During playback, a playback signal obtained through the magnetic head 23, switching circuit 22, and channel switch 24 is separated into an FM signal and a color signal by a low-pass filter 25, and the color signal is converted into the original color signal by a frequency conversion circuit 26. The FM modulated wave passes through a limiter circuit 27 and is demodulated by an FM demodulation circuit 28.

The demodulated signal is sent to the luminance signal separation circuit 29. A luminance signal time-axis compressed by the PCM signal separation circuit SO and the synchronization signal separation circuit 31, and a time-axis compressed FM signal.

Separate sync signals. The luminance signal is demodulated to the correct time axis by a time axis expansion circuit 52 to produce a color signal.

An adder circuit 53 adds the synchronizing signal and demodulates the video signal to the original video signal. The M signal is demodulated by a PcM signal processing circuit 5 which performs error detection, correction, dinterleave, D/A conversion, etc., and outputs it as an audio signal.

Figure S shows the time axis compression/expansion circuit used in the present invention.
This shows an example of a configuration using an analog memory such as D. In the same figure, 38 is data input, 39.40
are BBDs (analog memories), 41 and 42 are multiplexers, 45 is an inverter, 44 is a write clock, 45 is a read clock, 46 is a multiplexer clock, and 47 is a data output.

In FIG. 3, the manually input luminance signal data 3B is sampled by the memory write clock 44,
The data is stored in the analog memory 59. On the other hand, the analog memory 40 is read out with a read clock 45 that is one times the write clock 44 and is output to a data output 47 through a data selector (multiplexer) 41 . On the other hand, when predetermined data is written to the analog memory S9, the primary data is written to the analog memory 40, and at the same time, 1 of the write clock 44 is sent from the analog memory 59.
Double the readout time in 4 seconds! ! Make it stick out.

4. Of course, these controls are performed based on the synchronization signal. 6. What has been described above is about time axis compression, but in decompression, the relationship between the write clock and the read clock can be reversed. Returning further to FIG. 2, the M signal processing circuit 18. ! Synchronization with the synchronization signal is facilitated by configuring the system with 15 master clocks, a recording system, a reproduction system, and a PLL based on four synchronization signals. Furthermore, since the synchronization signal and the color signal are not subjected to time axis compression, it is better to further insert a delay compensation circuit in the synchronization signal system and the color signal system in order to compensate for the delay difference with the luminance signal. On the other hand, since 4-time axis compression is performed in the M signal 1 processing, a delay difference with the video signal is likely to occur, so in order to compensate for this, it is necessary to insert a delay compensation circuit into the video signal output of the reproduction system. Furthermore, frequency deviation can be eliminated by generating clocks for both the recording system and the reproducing system using pLL systems based on the synchronization signal. This situation is shown in Figure 4, where 58 is the input data, 44 is the write clock during recording, 4!1 is the read clock during recording, 46 is the multiplexer clock, and 47 is the time axis. This shows compressed luminance signal data. FIG. 5 shows the synchronization relationship between the time-base compressed luminance signal and the time-base compressed M signal. In other words, in the same figure, (a)
(b) the waveform of the video signal compressed in the time axis, (c) the waveform of the PCM audio signal, (b) the waveform of the M audio signal compressed in the 4-axis axis, 0) shows the waveform of the synchronization signal, and (g) shows the waveform of the FM modulated human input signal, respectively.

As described above, if the video tape recorder of the present invention is used, the frequency characteristics of the audio signal and the
/Nt can be dramatically improved for recording and reproduction.

[Brief explanation of the drawing]

Fig. 1 is an enlarged conceptual diagram of a tape pattern in a conventional VTR, Fig. 2 is a block diagram showing an embodiment of the present invention, Fig. 5 is a plotter diagram showing an example of the configuration of the time axis compression/expansion circuit in Fig. 2, FIG. 4 is a time chart of various signals in FIG. 3, and FIG. 5 is a signal waveform diagram for explaining multiple recording of audio signals and video signals according to the present invention. Description of symbols 12... Luminance signal separation circuit, 1... Synchronization signal separation circuit, 15... Luminance signal processing circuit, 16... Time axis compression circuit, 17... Synchronization circuit, 18.
...PcM signal processing circuit, 19.-synthesis circuit,
20-FM modulation circuit, 2B-FM demodulation circuit, 29
...Brightness signal separation circuit, 30-KM separation circuit,
Sl... Synchronization signal separation circuit, 52... Time axis expansion circuit, s s-pcM signal processing circuit. Oh l Tomoe

Claims (1)

[Claims] (1) At least a luminance signal time axis compression circuit, a time axis expansion circuit, an audio signal pulse code modulation circuit, a demodulation circuit, a pulse code modulated audio signal time axis compression circuit, and a time axis It is equipped with an expansion circuit, and when recording the input video signal and audio signal, the luminance signal separated from the video signal is compressed on the time axis by the time axis compression circuit, and the audio signal is converted into a pulse code by the pulse code modulation circuit. After modulating,
The time axis is compressed by the time axis compression circuit, and the compressed luminance signal and the pulse code modulated audio signal are serially synthesized on the time axis and recorded on the same track of the recording medium, and when reproduced, the recording medium Regarding the luminance signal and the pulse code modulated audio signal obtained by reproducing the luminance signal, the time axis of the luminance signal is expanded by the time axis expansion circuit,
A video tape recorder characterized in that the pulse code modulated audio signal is demodulated by the demodulation circuit, and then the time axis is expanded by the time axis expansion circuit before output. (2) PLL (phase-locked
loop) t-configured and used as a writing and reading clock for time axis conversion of luminance signals during recording and playback.'t*
A video tape recorder according to claim 1, in which the characteristics are as follows. 1) A PLL is configured using a synchronization signal that is synchronously separated from a video signal during recording and reproduction as a reference signal, and is used as a master clock of a PCH signal processing circuit including a pulse code modulation/demodulation circuit. Video tape recorder as described in section. +41 To compensate for the delay difference between the synchronization signal and the color signal that occurs due to time axis conversion of the luminance signal. 2. The video tape recorder according to claim 1, wherein delay compensation is performed on the color signal system and the synchronization signal system. (5) To compensate for the delay difference between the audio signal and the video signal that occurs in the final W signal processing, delay compensation is applied to the video signal system.
A video tape recorder according to claim 1, characterized in that: