JPH01268393A - Color video signal recording and reproducing device - Google Patents

Abstract

PURPOSE:To enlarge the recording current of a low frequency converting chrominance signal by recording a FM modulating luminance signal and the low frequency converting chrominance signal on separate tracks, thereby improving a resolution, easily designing a filter and preventing the generating of a bear. CONSTITUTION:The luminance signal is FM-modulated by an FM modulator 3, the carrier chrominance signal is frequency converted to the carrier frequency of the low frequency side by a frequency converter 4 and recorded as separate tracks by a first and a second rotary heads 17A, B;19A, B. Thereby, the resolution can be improved and the band of the luminance signal and the chrominance signal can be widened, as the characteristic of a filter inserted to a luminance signal system and a chrominance signal system, a strict one is not requested but the filter can be easily designed and the beat twice as high as the carrier frequency fc of the low frequency is not generated but even when the recording current of the low frequency converting chrominance signal is increased, the S/N of the low frequency converting chrominance signal can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a color video signal applied to record a color video signal on a recording medium by a rotating head and to reproduce the color video signal from the recording medium. The present invention relates to a signal recording and reproducing device.

[Summary of the invention]

In this invention, the luminance signal is FM-modulated, the carrier color signal is frequency-converted to a carrier frequency on the lower frequency side, and the FM-modulated luminance signal and the lower-frequency converted color signal are separately transmitted by the first and second rotating heads. recorded as a track.

The FM modulated luminance signal and low frequency converted color signal respectively reproduced from separate tracks are FM demodulated and frequency changed to reproduce a color video signal. Since the FM modulated luminance signal and the low frequency conversion color signal are reproduced from separate tracks, a reference signal synchronized with one edge of the horizontal synchronization signal is superimposed on the low frequency conversion color signal in order to match the phase of both. Ru. Furthermore, frequency conversion is performed on the reproduction side using the bias signal used when recording the low frequency conversion color signal, thereby improving APC.

In the present invention, since the FM modulated luminance signal and the low frequency conversion color signal are recorded on separate tracks, it is possible to solve the problem that would occur if both were recorded on the same track.

[Prior Art] Current color VTRs perform FM modulation on the luminance signal, frequency convert the chrominance signal, and record a recording signal in which the FM modulated luminance signal and the low frequency converted chrominance signal are multiplexed on the same track. For example, an apparatus for recording and reproducing color video signals is known, as described in Japanese Unexamined Patent Publication No. 157767/1983.

As stated in this publication, the carrier frequency is 743
．． The color signal that has been low frequency converted to 444 kHz and the luminance signal that has been FM modulated so that the sync chip is 4.2 M)fz and the white peak is 5.4 MHz are frequency multiplexed and are transferred to the same track on the magnetic tape. recorded in Also, 1.
An FM-modulated audio signal is superimposed with a center frequency of 5 MHz, and a pilot signal for AFT is also superimposed on the lower frequency side.

[Problem to be solved by the invention]

The method of recording an FM modulated luminance signal and a low frequency conversion color signal on the same track has various problems.

First, the bands of the luminance signal and color signal are limited. In particular, when the band of the luminance signal is narrow, the resolution is not good.

Second, filters included in the luminance signal system and the color signal system are required to have steep characteristics, making it difficult to design the filters. However, because the characteristics are steep,
The phase change is large, and a delay line is required to compensate for this phase change.

Thirdly, when an FM modulated luminance signal and a low-frequency converted color signal are mixed and recorded and reproduced, a beat with a frequency twice the low-frequency carrier frequency occurs in the reproduced signal, causing the analogy of a repeating image. to degrade.

Fourth, if the recording current of the low-frequency conversion color signal is increased, F
The sideband of the low-frequency conversion color signal enters the band of the M-modulated luminance signal, and the waveform of the FM-modulated luminance signal is affected. Therefore, there is a problem that the recording current for the low-range converted color signal cannot be increased, and the S/N of the low-range converted color signal is poor.

Therefore, an object of the present invention is to provide a color video signal recording and reproducing apparatus in which the above-mentioned problems of the conventional apparatus are solved by recording an FM modulated luminance signal and a low frequency conversion color signal on separate tracks. It is about providing.

[Means to solve the problem]

A color video signal recording device according to the present invention includes an FM modulator that performs FM modulation of a luminance signal, a frequency converter that converts a carrier color signal to a low carrier frequency, and an FM modulated luminance signal from the FM modulator and frequency converter. The apparatus includes first and second rotating heads for recording low-pass converted color signals from the receiver on separate tracks, respectively.

In the recording device according to the present invention, in order to match the time relationship between the luminance signal and chrominance signal recorded on separate tracks on the reproduction side, a reference signal synchronized with one edge of the horizontal synchronization signal is used together with the low-frequency conversion chrominance signal. recorded.

A color video signal reproducing device according to the present invention includes first and second rotary heads for reproducing an FM modulated luminance signal and a low frequency converted color signal respectively recorded on separate tracks; and reproduced low frequency converted color signals. The apparatus includes an extraction means for extracting a bias signal from the signal, and a frequency conversion circuit for converting the frequency of the low frequency converted color signal to the high frequency side based on the bias signal from the extraction means.

[Effect]

Since the FM modulated luminance signal and the low frequency conversion color signal are recorded on separate tracks, the problem of recording both on the same track can be solved. That is, the bands of the luminance signal and chrominance signal are not limited, and the resolution can be improved. Secondly, the design of the filters included in the luminance signal system and the chrominance signal system is facilitated.
Thirdly, it is possible to prevent the occurrence of beats, and fourthly,
The recording current for low-frequency conversion color signals can be increased.

Since the luminance signal and the low frequency conversion color signal are recorded on different tracks, it is necessary to match the timing between the reproduced luminance signal and color signal. For this reason, a reference signal synchronized with one edge of the horizontal synchronization signal is inserted into the low frequency conversion color signal. In the reproduction circuit, the horizontal synchronization signal separated from the luminance signal and the reference signal separated from the chrominance signal are phase-compared, and the phase of the chrominance signal is shifted so that the phases of the two coincide.

A bias signal is required when recording low-pass converted color signals. A continuous signal of a predetermined frequency is superimposed as this bias signal. Since the reproduced bias signal includes time axis fluctuations of the tape head system, a carrier wave for frequency conversion is formed from the reproduced bias signal, and the AP
C improvements are made.

(Embodiment) Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 shows the configuration of a recording system of this embodiment, and in Fig. 1, l is a composite color video signal. The input terminal 2 is a Y/C separation circuit.

The luminance signal Sy from the Y/C separation circuit 2 is sent to the FM modulation circuit 3.
, and an FM modulated luminance signal Yf is generated from the FM modulation circuit 3. As shown in FIG. 2A, the FM modulated luminance signal Yf has a sync chip level of 5 MHz,
It is modulated so that the white peak is 6.6 MHz.

The carrier color signal from the Y/C separation circuit 2 is transferred to the frequency conversion circuit 4.
supplied to A carrier wave of 4.27 MHz is supplied to the frequency conversion circuit 4 from an oscillation circuit 5 such as a crystal oscillator, and the carrier wave frequency is changed from 3.58 MHz to 688 kuz (fc
), a low frequency converted color signal CL is formed. The low frequency converted color signal CL is supplied to the adder circuit 6.

A horizontal synchronization signal sh is separated from the luminance signal sy by a synchronization separation circuit 7, and the horizontal synchronization signal sh is supplied to a double differentiation circuit 8. A reference signal Sr for timing alignment of the luminance signal and the color signal is generated from the double differentiator circuit 8, and this reference signal Sr is supplied to the adder circuit 6. FIG. 3A shows the horizontal synchronizing signal sh, and the double differentiator circuit 8 obtains the reference signal Sr shown in FIG. 3B, which has zero crossing points at the front and rear edges of the horizontal synchronizing signal ShO.

The output signal of the adder circuit 6 is supplied to the adder circuit 10 via a low-pass filter 9 for removing unnecessary signal components.

11A and IIB are input terminals for 2-channel audio signals, and the audio signals of each channel are FM
It is supplied to modulation circuits 12A and 12B. The center frequencies of the FM modulation circuits 12A and 12B are fl and f2. The output signals of the FM modulation circuits 12A and 12B are supplied to an adder circuit 13, and the adder circuit 13 generates an FM modulated audio signal Af. Since there is a margin of recording band on the high frequency side of the low frequency converted color signal CL, it is possible to FM-modulate and insert multi-channel audio signals.

The FM modulated audio signal Af is supplied to the adder circuit 14 . The adder circuit 14 is supplied with a bias signal sb having a frequency fo from an oscillation circuit 15 such as a crystal oscillator.The zero frequency fO is selected to be, for example, six times the low frequency carrier frequency fc. - By using the constant frequency bias signal sb, the differential gain (DC) characteristics of the low frequency conversion color signal can be improved compared to using the FM modulated luminance signal as the bias signal. The output signal of the adder circuit 14 is supplied to the adder circuit 10. As shown in FIG. 2B, the output signal of the adder circuit 10 is a signal obtained by frequency multiplexing the low frequency conversion color signal CL, the FM modulated audio signal Af, and the bias signal Sb.

The bias signal Sb has a phase variation corresponding to a time axis variation of the head/tape system. Therefore, as described below,
On the reproduction side, phase fluctuations in the carrier color signal are removed by APC, which uses a bias signal to form a carrier wave for frequency conversion.

Bias signal sb is not necessarily required. This is because the audio FM modulation signal At functions as a bias signal. For APC, the pilot burst signal Sp shown in FIG. 4A may be inserted into a period slightly narrower than the period of the horizontal synchronization signal.

The level of the pilot burst signal Sp is increased compared to the level of the original burst signal included in the carrier color signal Sc. A reference signal Sr for timing adjustment is inserted together with the pilot burst signal Sp as shown in FIG. 4B.

As a reference signal for timing adjustment, in addition to the above-mentioned double differential waveform signal Sr, the bias signal sb is FM modulated by a horizontal synchronization signal only during a period corresponding to the horizontal synchronization signal, and FM demodulated on the playback side. , a signal for timing adjustment may be obtained.

The FM modulated brightness signal Yf from the FM modulation circuit 3 is supplied to the rotary heads 17A and 17B via recording amplifiers 16A and 16B and rotary transformers (not shown), respectively. S)r
is recorded as track Ty on the magnetic tape 20. Low frequency conversion color signal CL from addition circuit 10, audio FM
A mixed signal of the modulation signal Af and bias signal sb is sent to recording amplifiers 18A, 18B and a rotating transformer (not shown).
0 supplied to the rotation Rads 19A and 19B through the
The rotary heads 19A and 19B record the output signal of the adder circuit 1O as a track Tc on the magnetic tape 20.

As shown in FIG. 5, the rotating heads 17A and 17B are
The rotary heads 19A and 19B are mounted on the rotating drum 21 with a facing interval of 80°, and similarly, the rotating heads 19A and 19B are spaced apart by 180°.
With a facing interval of is the 6th
As shown in the figure, the 0-rotation head 17B, which has different extending directions of gaps and is capable of recording with an inclined azimuth, has the same azimuth as the rotary head 17A, and the rotary head 19B has the same azimuth as the rotary head 17A. The extending direction of the gap between rotary heads L7A and 17B, which have the same azimuth as 19A and which record the FM modulated luminance signal Yf, is perpendicular to the track Ty.

The rotating drum 21 rotates at a frame frequency, and as shown in FIG. 7, parallel tracks Ty and Tc are simultaneously formed in one field period. The trunk TyO width W1 is, for example, 85 μm, and the width W2 of the track Tc is, for example, 5 μm.
It is assumed to be 2 μm. This track width value is the track width and guard band width in a Umatic standard VTR, and an existing tape running system can be used. Since the extending direction of the gap between the rotary heads 17A and 17B is perpendicular to the track, if a magnetic tape recorded according to the present invention is reproduced by a conventional U-matic VTR, it is possible to reproduce the luminance signal, and vice versa. Furthermore, if a magnetic tape recorded on a conventional VTR is played back using the VTR according to the present invention, the luminance signal can be played back. Of course, trucks Ty and T
The respective widths of c may be made equal.

FIG. 8 shows the configuration of the reproduction system. Rotating head 17A, 1
The reproduction signal of 7B is transmitted to the switching circuit 32 via a rotary transformer (not shown) and reproduction amplifiers 31A and 31B, respectively.
supplied to Similarly, the reproduction signals of the rotary healds 19A and 19B are transferred to a rotary transformer (not shown) and a reproduction amplifier 33.
A and 33B are supplied to the switching circuit 34, respectively.

Although not shown, switching pulses synchronized with the rotation of the rotary head are supplied to the switching circuits 32 and 34, and continuous reproduction signals are obtained by the switching circuits 32 and 34.

The reproduction signal of the track Ty obtained from the switching circuit 32 is supplied to the FM demodulation circuit 35.
The luminance signal sy is obtained from. The reproduced luminance signal sy is supplied to an adder circuit 37 via a delay circuit 36 having a fixed delay amount, and is added to a reproduced color signal Sc obtained as described later.

A reproduced color video signal is obtained at the output terminal 38 of the adder circuit 37. Further, the luminance signal sy is taken out via the amplifier 39 to an output terminal 40 for dubbing.

The reproduction signal of the track TC obtained from the switching circuit 34 is passed through the low-pass filter 41 and the band-pass filter 4.
2 and bandpass filters 43 and 44.

The low-pass filter 41 separates the low-pass converted color signal CL including the reference signal Sr. Bandpass filter 42
Thus, the bias signal sb is separated. Bandpass filters 43 and 44 separate the two channels of audio FM modulation signals Af.

The output signal of the low-pass filter 41 is supplied to a variable delay line 45 composed of, for example, a CCD.

The output signal of the variable delay line 45 is supplied to a reference signal separation circuit 46 and a reference signal removal circuit 49. The reference signal separation circuit 46 separates, for example, the front waveform of the reference signal Sr. The reference signal Sr is separated by gating with a pulse signal formed from a burst signal, for example.

The reference signal Sr (front side waveform) is supplied to the PLL 47. The PLL 47 is supplied with a horizontal synchronization signal separated from the reproduced luminance signal by a synchronization separation circuit 48. In the PLL 47, the zero-crossing point of the front waveform of the reference signal Sr and the front edge of the horizontal synchronization signal are phase-compared, and the oscillation frequency of the VCO (voltage-controlled oscillation circuit) is controlled by the phase comparison output.

The output signal of this VCO or the frequency dividing circuit connected to vCO is supplied to the variable delay circuit 45 as a clock signal.

The delay amount of the variable delay circuit 45 is varied depending on the frequency of the clock signal from the PLL 47. When the zero crossing point of the front waveform of the reference signal Sr and the front edge of the horizontal synchronizing signal are in the same phase, the VCO oscillates at the center frequency and the delay amount of the variable delay circuit 45 becomes a predetermined value. This predetermined delay amount and the delay amount of the delay circuit 36 inserted into the luminance signal system are selected to be equal. The PLL 45 and the variable delay circuit 45 are controlled so that the zero-crossing point of the front waveform of the reference signal and the front edge of the horizontal synchronization signal are in phase with each other. The variable delay circuit 45 allows another track T)F and T
The time relationship between the luminance signal and the color signal reproduced from c is combined.

The low frequency conversion color signal CL from the reference signal removal circuit 49 is AC
The output signal of the frequency conversion circuit 54 is supplied as a carrier wave to the zero frequency conversion circuit 51 which is supplied to the frequency conversion circuit 51 via the C circuit 50 and taken out to the output terminal 53 for dubbing via the amplifier 52. The output signal of the 0-frequency conversion circuit 51 is supplied to a bandpass filter 57 for removing unnecessary signal components, and the carrier color signal Sc from the bandpass filter 57 is supplied to the addition circuit 37 and added to the reproduced luminance signal Sy. be done.

Bias signal sb separated by bandpass filter 42
is divided into (1/6) by the frequency dividing circuit 56 and supplied to the frequency converting circuit 54. The frequency conversion circuit 54 receives a frequency of 3.58 M) from an oscillation circuit 55 such as a crystal oscillator.
Therefore, a carrier wave signal of 4.27 MHz is obtained from the frequency conversion circuit 54. Since this carrier wave signal is supplied to the frequency conversion circuit 51, from the frequency conversion circuit 51, the original carrier wave frequency 3.58M) Iz
A carrier color signal of

The bias signal sb, which is a continuous wave, has the same time axis variation as the low-frequency conversion color signal. Therefore, when the frequency of the low frequency converted color signal CL is converted by the carrier wave signal from the frequency conversion circuit 54, the time axis variation is canceled. This operation is called APC.

Furthermore, the output signals of the bandpass filters 43 and 44 are F
The signals are supplied to M demodulation circuits 58 and 59, where the audio FM modulation signals are demodulated, and two-channel audio signals are obtained at output terminals 60 and 61, respectively.

〔Effect of the invention〕

In this invention, since the FM modulated luminance signal and the low frequency conversion color signal are recorded on separate tracks, the problems of the conventional recording and reproducing apparatus that frequency-multiplexes both signals and records them on the same track can be solved as follows. , can be solved.

First, the bands of the luminance signal and color signal can be expanded, and the resolution can be improved.

Second, the characteristics of the filters inserted into the luminance signal system and the chrominance signal system are not required to be very strict, making it easier to design the filters, and reducing the phase change caused by the filters, making it easier for phase compensation. The circuit becomes simple.

Third, beats at twice the low carrier frequency fc do not occur, and the quality of reproduced images can be improved.

Fourth, even if the recording current of the low-band converted color signal is increased, there is no fear that the waveform of the FM modulated luminance signal will be affected by the sideband of the low-band converted color signal, and the S/ N can be made good.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the circuit configuration of a recording system according to an embodiment of the present invention, FIG. 2 is a diagram showing the spectrum of a recording signal,
Figure 3 is a waveform diagram of an example of a reference signal for phase matching;
The figure is a waveform diagram of the pilot burst signal, Figure 5 is a route map showing the configuration of the head/tape system, Figure 6 is a diagram showing the configuration of the rotating head, Figure 7 is a route map showing the recording pattern, and Figure 8 is a route map showing the configuration of the rotary head. 1 is a block diagram of a reproduction system according to an embodiment of the present invention. Explanation of main symbols in the drawings 3.12A, 12B: FM modulation circuit, 4.51, 54: Frequency conversion circuit, 5.15, 55: Oscillation circuit, 8: Double differentiation circuit, 17A, 17B, 19A, 19B : rotating head, 35.
58, 59: FM demodulation circuit, 45: variable delay circuit. Agent Patent Attorney Masatoshi Sugiura

Claims (3)

[Claims] (1) An FM modulator that performs FM modulation on a luminance signal, a frequency converter that converts a carrier color signal into a low frequency carrier frequency, and a low frequency conversion between the FM modulated luminance signal from the FM modulator and the frequency converter. 1. A color video signal recording apparatus comprising first and second rotary heads for recording color signals on separate tracks. (2) The color video signal recording device according to claim 1, wherein a reference signal synchronized with one edge of a horizontal synchronization signal in the luminance signal is superimposed on the low-frequency conversion color signal. (3) first and second rotating heads for reproducing the FM modulated luminance signal and the low frequency converted color signal respectively recorded on separate tracks; and extraction for extracting the bias signal from the reproduced low frequency converted color signal. A color video signal reproducing device comprising: means; and a frequency conversion circuit for converting the frequency of the low frequency converted color signal to a high frequency side based on the bias signal from the extraction means.