JPS62176393A - Magnetic picture recording system - Google Patents

Abstract

PURPOSE:To obtain the video signal of high resolution by separating a wide band luminance signal into a low frequency component and a high frequency component, converting the high frequency component into the low frequency component, right angle two phase modulating both low frequency components by a sub-carrier and right angle two phase modulating both chrominance signals by the sub-carrier having a phase shifted by 45 deg.. CONSTITUTION:The luminance signal Y is passed through an LPF 27 to form the low frequency luminance signal YL, the Y signal and the YL signal are applied to a differential amplifier 30 to have the high frequency luminance signal YH, it is guided to a frequency shift circuit 31 to convert into a converted high frequency luminance signal YH'. The output of a crystal oscillator 34 is guided to a 45 deg. phase shifting device 35, the obtained sub-carrier SC' and the signals YL, YH' are guided to the right angle two phase modulator 32 to form the modulated luminance signal Y', the chrominance signals CW and CN are guided to the right angle two phase modulator 33 to obtain the modulated chrominance signal C'. The output of a synchronizing signal generator 37 and a burst signal from a burst forming circuit 36 are supplied to mixing circuits 38, 39, added to the modulated signals Y', C' to form signals Ysb, Csb and they are recorded on a tape 46 by recording heads 44, 45 of two channels through FM modulators 40, 41, and amplifiers 42, 43.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic recording system suitable for simple VTRs, etc., and in particular records a video signal with a wider band than conventionally on a magnetic tape with a small number of channels, thereby reducing the complexity time base correction device (TBC)
This invention relates to a magnetic recording method that allows playback without the use of magnetic tape.

[Conventional technology]

Traditionally, simple VTRs for home use, etc., have (CO)γ-
Signal processing using oxide magnetic powder coated tape (oxide tape) such as FeJ3, ferrite core head (ferrite head), and low-frequency conversion color signal recording method (see page 176 of Broadcasting Technology Book RVTR Technology edited by Japan Broadcasting Corporation) It is made up of a combination of circuits.

Figure 3 shows the video signal system block of a conventional simple VTR.
FIG. 4 shows the recording signal frequency array.

In FIG. 3, 1 is a low-pass filter (LPF),
2 is a band pass filter (mouth PF), 3 is Y/C
1411 circuits, 4 is FM modulator, 5 is local oscillator, 6 is
is a frequency shift circuit, 7 is an adder, 8 is a recording amplifier, 9
is the recording head, lO is the tape, 11 is the playback head, 12
is a regenerative amplifier, 13 is a bypass filter (HPF),
+4 is a low pass filter (LPF), 15 is an FM demodulator, 16 is a frequency shift circuit, 17 is a frequency converter, 1
8 is a voltage controlled oscillator (Vfl: 0), 19 is a phase comparator, 20 is a local oscillator, 21 is a synchronous separation circuit, 22 is a low-pass filter, 23 is a band-pass filter, 24 is an adder, 25 is a Y/C synthesizer It is a circuit.

In the combination of conventional oxide tape and ferrite head, the shortest recording wavelength is 0.8 μm, and the upper limit of the recording frequency is determined by the relationship of [recording frequency = relative speed / recording wavelength], so the relative speed (relative speed) of the tape head is 7 m/s
When this happens, it becomes approximately 8.5Ml+z.

[Problems to be solved by the invention] As mentioned above, in the combination of an oxide tape and a ferrite head, which is a conventional tape/head system, the shortest recording wavelength was 0.8 μm, but recently it has been put into practical use. Started F
Metal powder coated tapes (metal tapes) such as e and Go, evaporated tapes such as Fe and Go which are currently in the process of research and development, Da Mitsuelite microcrystal coated tapes and Sendust (Fe-5i-A1 alloy), etc. In the combination of the metal spatula S9 as the core, the shortest recording wavelength is 0.
When shortened to 4 μm and the relative velocity is 7 m/s, the upper limit of the recording frequency reaches 17.5 MHz.

As mentioned earlier regarding the conventional technology, when the upper limit of the recording frequency is approximately 8.5 MHz, the frequency arrangement of the recording signal is as shown in Fig. 4, and the band of the luminance (Y) signal is 3 MHz.
, the band of the color (C) signal is as narrow as 650 kl (z).

Therefore, an object of the present invention is to increase the frequency band in which recording and playback can be performed while keeping the relative speed between the tape and the head the same as before.
For example, the object of the present invention is to provide a magnetic recording system that increases the luminance signal by twice and the chrominance signal by up to five times, thereby obtaining a video signal with a much higher resolution than the conventional one.

For example, by implementing the tree invention, a new tape head system with an upper limit of recording frequency reaching 17.5 MHz can be effectively utilized to achieve a Y signal band of 6 MHz.

This is intended to record and reproduce a wideband video signal in the C signal band of 3 MHz.

[Means for Solving the Problems] In the magnetic recording system according to the present invention, during recording, a wideband luminance signal is separated into a low frequency component and a high frequency component, the high frequency component is converted to a low frequency component, and both of these components are separated. The low-frequency signal is quadrature two-phase modulated with a subcarrier, and the wideband and narrowband flesh color A3 are quadrature two-phase modulated with a 45° phase-shifted subcarrier, and these luminance signal components and color are modulated with the burst subcarrier. Signal components are recorded using FM modulation, and during reproduction, synchronous detection is performed using subcarriers that are continuously reproduced after FM demodulation to restore the original signal.

(Example) Next, the tree invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of a video signal system of a simple VTR to which the present invention is applied. In this figure, 26 is a matrix circuit, 27, 28, 29 are low-pass filters, 30 is a differential amplifier, 31 is a frequency shift circuit, 32, 33 is a quadrature two-phase modulator, 34 is a crystal oscillator, and 35 is a 45° square Aiki, 3
6 is a burst forming circuit, 37 is a synchronization signal generator, 38.
39 is a mixing circuit, 40.41 is an FM modulator, 42.43
is a recording amplifier, 44.45 is a recording head, 46 is a tape, 47.48 is a playback head, 49.50 is a playback amplifier,
51.52 is an RF equalizer, 53.54 is an FM demodulator, 5
5.56 is a distributor, 57.58 is a burst extraction circuit, 5
9.60 is voltage controlled oscillator (Vfl:O), 61 is 4
5° phase shift circuit, 62.63 is a synchronous detector, 64 is a frequency shift circuit, 65 is an addition circuit, 66 is a matrix circuit,
67 is a synchronous separation circuit.

In addition, Fig. 2 (A) shows the recording signal frequency array of the VTR shown in Fig. 1, Fig. 2 (B) shows the recording signal waveform of the same VTR, and Fig. 2 (C) shows the quadrature two-phase modulation signal. Y', C'
FIG. 3 is a diagram showing the phase relationship between burst B and burst B.

Next, with reference to FIG. 1 and FIGS. 2 (A) to (C),
The operation of this embodiment will be explained.

First, the three primary color signals R and G from the color camera.

B (bandwidth 6 to 8 M each) Iz) to matrix circuit 2
6, the luminance signal Y of band 6 MH2 and band 3
MHz color signals Cwt and CH are obtained.

For the Y signal, in order to create two signals with a band of 3 MHz, we first applied a low-pass filter (cutoff frequency 3 MHz).
) Iz) The frequency spectrum is 0 to 3 M through 27
A low frequency luminance signal YL of Hz is formed. Next, the Y signal and this YL signal are applied to the differential amplifier 30 to obtain a high frequency luminance signal YH having a frequency spectrum of 3 to 6 MHz.

Furthermore, by introducing the YH signal into the frequency shift circuit 31, it is converted into a converted high-frequency luminance signal YH' having a frequency spectrum of 0 to 3 MHz. Thus, band 0
~6M) Iz Y signal can be divided into two systems of signals YL and YH' with a band of 0 to 3MHz.

On the other hand, a 3.58 M)lz crystal oscillator 34 is prepared, and its output is introduced into a 45° phase shifter 35 to obtain a subcarrier sc.
' and the aforementioned two systems of signals (YL, YH') are guided to a quadrature two-phase modulator 32 to obtain a modulated luminance signal Y'.

For color signals, C11 each has a band of 3 MIIz.
1, CN signals to another quadrature two-phase modulator 33 to form a modulated color signal C'. At this time, the output of the crystal oscillator 34 is directly used as the subcarrier.

Next, by supplying the output of the synchronizing signal generator 37 and the burst signal of 3,58 MI (z) obtained from the burst forming circuit 36 to the mixing circuit 38, 39, the modulation is performed as shown in FIG. 2(B). It is added to signals Y' and C' to form signals YSb, (:sb).

Here, the phase relationship between modulated signals Y' and C' is as shown in FIG. 2(C).

The signals Ysb and Csb are FM modulated by FM modulators 40 and 41, and sent to tape 4 by a two-channel recording head 44 and 45 via recording amplifiers 42 and 43, respectively.
Record in 6. The frequency array of this recording signal is shown in Figure 2 (
As shown in A).

Next, the signal reproduced from the tape 46 by the reproduction head 47.48 is introduced into an RF equalizer 51.52 via a reproduction amplifier 49.50, where it is equalized by RF times suitable for demodulation. Further, demodulation is performed by FM demodulators 53 and 54 to obtain demodulated signals Ysb' and Csb' (Fig. 2(B)
, (C)).

The signals YSb' and csb' are passed through distributors 55 and 56 to a video signal system (V) and a subcarrier reproduction system (SC).
).

In the subcarrier reproduction system, the burst signal B is extracted from the signals Ysb' and Csb' by burst extraction circuits 57 and 58, and the 3.58 MHz signal is synchronized with this burst signal B.
z continuous wave SC with voltage controlled oscillator (VCO) 59.60
Generate with . The output of the VCO 59 is led to a synchronous detector 62 via a 456 phase circuit 61 to extract the low-frequency component YL (0 to 3M) Iz) and converted high-frequency component YH' (0 to 3MIIz) of the reproduced Y signal. . The latter converted high frequency component YH' is introduced into the frequency shift circuit 64 and
~6MHz frequency spectrum. Then, it is added to the adder circuit 65 together with the former low frequency component YL, and the continuous frequency spectrum (0 to 6 Ml(z)
A reproduced Y signal is formed.

The reproduced signal Csb' and the output of the VCO 60 are introduced into a separate synchronous detector 63, which divides the frequency spectrum 0 to 3.
MHz CW and CN signals are output. Then, along with the Y signal described above, the signal is inputted to the matrix circuit 66 to obtain reproduced R, G, and B signals with a bandwidth of 6 MHz.

Further, the Ysb' signal is introduced into the synchronous separation circuit 67, and the RG
A reproduction horizontal drive pulse HD and a reproduction vertical drive pulse VD are obtained to be supplied to the external synchronization input terminal of the B color monitor.

In the above explanation, the phase of the subcarrier in the modulated luminance signal Y' and the modulated color signal C' is shifted by 45° for the following reason. In other words, there is a signal Y′ on the tape.
and C' are recorded side by side, so during playback, the head 47 for signal Y plays back part of the track of signal C on the tape due to a tracking error in head scanning, while the head 47 for signal C plays back a part of the track of signal C on the tape. A part of the track of signal Y on the tape may be played back. Therefore, even when these unnecessary signals are manually input to the synchronous detectors 62 and 83, consideration has been given to ensuring that the unnecessary signals are suppressed and output as the detection output.

Also, subcarriers are used as signals YL, YH', Cw, C
Any of double sideband modulation, vestigial sideband modulation, and single sideband modulation may be applied as a modulation method for quadrature two-phase modulation with NI.

(Effects of the invention) The combination of oxide tape and ferrite head, which was conventionally used in home VTRs, has now been replaced by metal tape, vapor-deposited tape, and combinations of Ba ferrite tape and metal head, and the shortest recording wavelength has been improved. However, according to the present invention, this phenomenon can be positively applied to expand the band of recording/reproducing signals.

In other words, by implementing the present invention, the frequency band that can be recorded and reproduced at the same relative speed as before can be doubled for Y signals and 5 times for C signals, so the resolution is much higher than before. It becomes possible to record and play back high-quality video signals.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the video signal system of a simple VTR to which the present invention is applied, FIG. 2 (A) is a diagram showing the recording signal frequency arrangement of the VTR shown in FIG. 1, and FIG. ) is a waveform diagram showing the recording signal of the VTR shown in FIG. 1, and FIG.
Figure 3 is a block diagram showing the video signal system of a conventional simple VTR; Figure 4 is a diagram showing the recording signal frequency arrangement of the VTR shown in Figure 3. It is. 1...Low pass filter (LPF), 2...Band pass filter (BPF), 3...Y/C separation circuit, 4...FM modulator, 5...Local oscillator, 6... Frequency shift circuit, 7... Adder, 8... Recording amplifier, 9... Recording head, 10... Tape, 11... Playback head, 12... Playback amplifier, 13... Bypass Filter (HPF), 14...Low pass filter (LPF), 15...FM demodulator, 16...Frequency shift circuit, 17...Frequency converter, 18...Voltage controlled generator (VCO) ), 19... Phase comparator, 20... Local oscillator, 21... Synchronization separation circuit, 22... Low pass filter, 23... Band pass filter, 24... Adder, 25...・Y/C synthesis circuit, 26... Matrix circuit, 27.28.29... Low pass filter, 30...
Differential amplifier, 31... Frequency shift circuit, 32.33... Quadrature two-phase modulator, 34... Crystal oscillator, 35... 45° phase shifter, 36... Burst forming circuit, 37 ...Synchronizing signal generator, 38.39...Mixing circuit, 40.41...F wheat adjuster, 42.43...Recording amplifier, 44.45...Recording head, 46... tape, 47.48... reproducing head, 49.50... reproducing amplifier, 51.52... RF equalizer, 53.54... FM demodulator, 55.56... distributor, 57.58... Burst extraction circuit, 59.60... Voltage controlled oscillator (VCO), 61.
...45° phase shift circuit, 62.63... Synchronous detector, 64... Frequency shift circuit, 65... Addition circuit, 66... Matrix circuit, 67... Synchronous separation circuit.

Claims (1)

[Claims] 1) During recording, a wideband luminance signal is separated into a low frequency component and a high frequency component, the high frequency component is converted to a low frequency range, and both of these low frequency signals are quadrature two-phase modulated with a subcarrier. The narrowband bichromatic signal is quadrature-two-phase modulated using the subcarrier with a 45° phase shift, and the luminance signal component and color signal component are FM-modulated and recorded along with the burst-like subcarrier, and during playback, after FM demodulation. A magnetic recording method characterized by synchronous detection using continuously reproduced subcarriers to restore the original signal.