JPS61170907A - Video tape recorder - Google Patents

Abstract

PURPOSE:To output a reproducing signal instead of a luminance signal by providing a means which selects either of the luminance signal and a signal other than the luminance signal and a means which imposes frequency modulation upon the signal other than the luminance signal. CONSTITUTION:The frequency-modulated signal is supplied to an adder 25 and superposed additively upon a pilot signal generated by a pilot signal generat ing circuit 30 and the resulting signal is supplied to a rotary head through an amplifier 26 and a switch 27 and then recorded on a magnetic tape. The chroma signal in a video signal is extracted separately from the luminance signal and supplied to an amplifier 26 after low-band conversion, so that the signal is recorded together. A playback signal from an amplifier 28 is demodulated by a demodulating circuit 29 and the luminance signal is outputted through a switch 23. Consequently, the signal other than the luminance signal is outputted and, for example, an EFM signal, etc., are recorded on and repro duced from a magnetic tape.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a video tape recorder for recording and reproducing television video signals on a magnetic tape.

[Conventional technology]

Recently, optical digital audio discs and their players have become popular. This disc modulates the audio signal into a digital signal, which is then further processed by EF.
Since it is recorded using M modulation, you can enjoy high quality musical sounds. However, this disc is for playback only, and such high-quality audio signals could not be recorded or played back on other devices in ordinary households other than playing back on a dedicated player. One of the major reasons for this problem is that the EFM signal, which is a recording signal, has a wide frequency spectrum from a DC component to about 2 MHz. Devices that can directly record and play back such wideband signals include, for example, DRAW disks, E-DRAW disks, and other devices, and devices that record and play back signals after converting them into analog signals use the EIAJ format. There are video tape recorders, etc.

[Problem that the invention seeks to solve]

However, recording and reproducing devices for DRAW discs and E-DRAW discs are still expensive and cannot be used in general households. Furthermore, in EIAJ format video tape recorders, the playback signal from the disc is first converted into an analog signal before recording.
The drawback was that the sound quality inevitably deteriorated.

[Means for solving problems]

FIG. 1 is a block diagram of a video tape recorder according to the present invention. In the figure, reference numeral 1 denotes a magnetic tape, which is run at a predetermined speed by a capstan 2 and a pinch roller 3. Reference numeral 4 denotes a rotating drum having, for example, a rotary transformer (not shown) inside, two rotating heads spaced apart from each other by 180 degrees, and the like. Reference numeral 5 denotes a motor that rotates the rotary drum 4, and includes a pulse generator (PG) and a frequency generator (FG) (not shown) inside.

The pulse generator outputs two pulses per revolution of the rotary drum 4, corresponding to the position of the rotary head.

From this output, the head switching signal generating circuit 6 generates a head switching signal whose period corresponds to one revolution of the rotary drum 4. The output of the phase comparator circuit 7, to which the head switching signal is supplied to one input, is connected to an adder 8 and an amplifier 9.
is supplied to the motor 5 via. The output of the frequency generator is amplified and waveform-shaped by an amplifier 10, converted into a voltage by a frequency voltage conversion circuit 11, and compared with a reference voltage (not shown), and the error signal thereof is input to an adder 8.

That is, a frequency generator, an amplifier 10, a frequency-voltage conversion circuit 11. A frequency servo loop is formed by an adder 8 and an amplifier 9, and a phase servo loop is formed by a pulse generator, a head switching signal generation circuit 6, and a phase comparison circuit 7. 12 is a motor for rotating the capstan 2. It has a frequency generator (not shown) inside.

The output of the frequency generator is amplified and waveform-shaped by an amplifier 13, and converted into a voltage by a frequency-voltage conversion circuit 14.
I-converted and compared with a reference voltage (not shown), and the error signal is sent to an adder 15. Motor 12 via amplifier 16
are supplied to the motor 12, and these form a frequency servo loop for the motor 12. 17 is a reference signal generation circuit that outputs a reference signal having the same frequency as the head switching signal. 18 is a phase comparator circuit, which compares the phase of the reference signal and
The output of the amplifier 13 is frequency-divided to the same frequency as the reference signal, and the phase of the output of the frequency dividing circuit 19 is compared with that, and the error signal is supplied to the adder 15 via the switch 20. The reference signal is also supplied to the other input of the phase comparison circuit 7 via the switch 21. Switch 21 is switch 22.2
It is linked to 3. 24 is a frequency modulation circuit which frequency-modulates the EFM signal from the optical digital audio disc input via the switch 22 or the luminance signal of the television image signal from the video disc player, and outputs the result to the adder 25. (Of course, the frequency modulation circuit is
(The output may be selectively selected.) This output is supplied to the rotary head via a recording amplifier 26 and a switch 27. 28 is switch 27
This is a reproducing amplifier that amplifies the signal input through the E
An FM signal and a luminance signal are each outputted via a switch 23.

3o corresponds to the head switching signal and has a frequency of 6.5.
fIl, 7.5fw, 10.5fl, 9.5fs
This is a pilot signal generation circuit that sequentially generates and outputs tracking pilot signals of (fm is the frequency of the horizontal synchronization signal). This pilot signal is input to an adder 25 and a multiplier 31. The multiplier 31 outputs a signal obtained by multiplying the reproduced signal from the amplifier 28 and the pilot signal from the pilot signal generation circuit 3o. From this output, the beat frequencies (fw and 3fl) between the crosstalk components of the pilot signal from the adjacent track and the pilot signal from the pilot signal generation circuit 30 are extracted by bandpass filters 32 and 33 having center frequencies of fll and 3fl, respectively. The components are extracted. The level of this beat component is detected by the detection circuits 34 and 35, and the difference between the levels is outputted from the differential amplifier 36 to the adder 15 via the switch 20, and tracking control is performed using a so-called 4-frequency pilot signal. It looks like this.

A vertical synchronizing signal separation circuit 37 separates and extracts a vertical synchronizing signal from the input luminance signal and supplies the vertical synchronizing signal to the phase comparator circuit 7 via a switch 38.21.

[Effect]

The effect will now be explained. When recording a video signal, switches 21, 22, and 23 are placed on the contact V side, and switch 20 is placed on the contact V side.
．． 27 and 38 are respectively switched to the contact R side. When the motor 5 rotates the rotary drum 4, its frequency generator outputs a signal at a frequency corresponding to the rotation. This signal is amplified and waveform-shaped by an amplifier 10, converted into a voltage corresponding to the frequency (and hence rotation) by a frequency-voltage conversion circuit 11, and an error signal with respect to the reference voltage is sent to an adder 8 and an amplifier 9.
is supplied to the motor 5 via. That is, frequency servo is performed by this system. Also, the phase of the head switching signal generated in response to the signal output by the pulse generator of the motor 5 and the vertical synchronization signal separation circuit 37. switch 3
The phase comparison circuit 7 compares the phases of the vertical synchronization signals in the luminance signals inputted via 8.21, and a signal corresponding to the phase difference is supplied to the adder 8. Therefore, phase servo is performed by these systems, and the five-rotation drum 4 rotates in synchronization with the vertical synchronization signal. On the other hand, the signal from the frequency generator of the motor 12 is supplied to the frequency-voltage conversion circuit 14 via the amplifier 13 and converted into a voltage.
2, and the frequency servo of the motor 12 is performed.

In addition, the phase comparison circuit 18 compares the reference signal output from the reference signal generation circuit 17 with the amplifier 1 output from the frequency division circuit 19.
The phase difference with the frequency-divided output of 3 is detected and supplied to the adder 15 via the switch 20, where phase servo is performed.

In the frequency modulation circuit 24, a carrier wave of a predetermined frequency is controlled by a luminance signal input via the switch 22 so that, for example, the peak value of the synchronization signal -4.
2 MHz, and the frequency is modulated so that the peak value of the white level is 5.4 MHz. As the bandwidth of this luminance signal, 3.2 MHz is secured from 4.8 MHz, which is the center frequency of the carrier wave, to 1.6 MHz, which is the upper limit of the audio signal band. This frequency-modulated luminance signal is supplied to an adder 25, where a pilot signal generation circuit 30
is added and superimposed with the pilot signal outputted by the amplifier 26.
, the signal is supplied to the rotary head via the switch 27, and recorded on the magnetic tape. The chroma signal in the video signal is
'The signal is extracted separately from the luminance signal, and after being low-frequency converted, is supplied to the amplifier 26 and recorded together.

Next, the case of reproducing a video signal will be explained.

In this case, the switches 21, 22, 23 are switched to the contact V side, and the switches 20, 27, 38 are switched to the contact P side.

Therefore, the reference signal output from the reference signal generation circuit 17 is input to the phase comparison circuit 7 via the switch 38.21.
A phase servo is applied to the motor 5 so that it rotates in synchronization with the reference signal.

On the other hand, the pilot signal outputted by the pilot signal generation circuit 3o, the one-rotation head, and the switch 27. The reproduced signal supplied via the amplifier 28 is multiplied by the multiplier 31, and a tracking error signal is generated by the bandpass filter 32.33, the detection circuit 34.35, and the differential amplifier 36.
Since the signal is supplied to the adder 15 via the switch 2o, the motor 12 is subjected to phase servo so that the tracking error signal is reduced. Regarding frequency servo, both motors 5 and 12 are the same as in the case of recording a video signal.

Then, the reproduced signal from the amplifier 28 is demodulated by the demodulation circuit 29, and a luminance signal is outputted via the switch 23.

When recording EFM signals, switch 21.22.2
3 is switched to the contact E side, and switches 20, 27, and 38 are switched to the contact R side. Most of the spectrum of the EFM signal is distributed from 〇7 to about 2MHz, but for example, its low level is the peak value of the horizontal synchronization signal of the luminance signal,
After the level is set so that the high level becomes a binary logic corresponding to the peak value of the white level, the switch 2
2 to the frequency modulation circuit 24. Then, the low level is frequency modulated to 4.2 MHz and the high level is frequency modulated to 5.4 MHz, and most of the spectrum of the EFM signal can be distributed within the band of the luminance signal. In this case, if the EFM signal has jitter, the input EFM signal
The six-frequency servo signal, which may be reproduced by extracting the clock from the signal and using the clock, is added to the pilot signal by the adder 25 and recorded on the magnetic tape 1 by the one-rotation head. Since the EFM signal does not include a vertical synchronization signal, the reference signal is input to the phase comparator circuit 7 via the switch 21 to perform phase servo of the motor 5, frequency servo of the motor 5, and phase and frequency servo of the motor 12. This is the same as when recording a video signal.

If you want to further reproduce the EFM signal, switch 21.2
2.23 is switched to the contact E side, and the switch 20° 27.38 is switched to the contact P side. The reproduced signal from the 0 rotation head is supplied to the switch 27, the amplifier 28, and the demodulation circuit 29.
An EFM signal is output via switch 23. The phase and frequency servo of the motor 5 in this case is EFM
This is the same as when recording a signal, and the phase and frequency servo of the motor 12 are the same as when reproducing a video signal.

When reproducing an EFM signal, a clock signal is extracted from the reproduced signal, its frequency is detected, and the magnetic tape 1 is rotated in accordance with the detected output so that the frequency is equal to the frequency of a predetermined reference clock. It is also possible to control the relative speed of the heads. Alternatively, control signals generated in other devices (for example, audio circuits including decoding, correction circuits, D/A conversion circuits, etc.) connected to the EFM signal output terminal of the video tape recorder may be supplied to the video tape recorder. You can also control the relative speed by Furthermore, if the video tape recorder has a decoding, correction circuit, D/A conversion circuit, etc.
When reproducing an FM signal, the signal reproduced from the magnetic tape 1 is supplied to those circuits.
FMm';+.

may be directly supplied to those circuits and monitored by the E-E system.

The present invention relates to an optical digital audio disc E.
Application is possible not only to FM signals but also to other digital signals and analog signals.

In that case, the lowest level of the analog signal can correspond to the peak value of the synchronization signal, and the highest level can correspond to the peak value of the white level. Furthermore, the spectrum of the recording signal, the center frequency of the carrier wave, etc. are not limited to the examples described above.

〔effect〕

As described above, the present invention provides a video tape recorder that frequency-modulates the brightness signal of a television video signal, records it on a magnetic tape using a rotating head, and demodulates and outputs the reproduced signal. A selection means for selectively selecting one of the signals, and a modulation means for frequency modulating a signal other than the luminance signal, and a frequency modulated signal other than the luminance signal is replaced with the luminance signal by a rotating head. Since it is possible to record on magnetic tape, demodulate the reproduced signal, and output signals other than the luminance signal instead of the luminance signal, it is possible to record EFM signals etc. on the magnetic tape in a normal home video tape recorder. Can be played.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a video tape recorder according to the present invention. 1;...Magnetic tape 2...Capstan 3...
Pinch roller 4...Rotating drum 5.12...Motor 6...Head switching signal generation circuit 7.18...Phase comparison circuit 8.15.25...Adder 11.14...Frequency Voltage conversion circuit 17... Reference signal generation circuit 24... Frequency modulation circuit 29... Demodulation circuit 3o.
... Pilot signal generation circuit 31 ... Multiplier 37 ... Vertical synchronization signal separation circuit or higher

Claims (1)

[Claims] (1) In a video tape recorder that frequency-modulates the brightness signal of a television video signal, records it on a magnetic tape using a rotating head, and demodulates and outputs the reproduced signal,
A selection means for selectively selecting one of the luminance signal and a signal other than the luminance signal, and a modulation means for frequency modulating the signal other than the luminance signal, The rotary head records the signal on the magnetic tape instead of the luminance signal, demodulates the reproduced signal, and outputs the signal other than the luminance signal instead of the luminance signal. video tape recorder.